Cardiac Disorders
Cardiogenic Shock
Heather Sowinski
Background/Definition
Inability of the heart to meet the metabolic demands of the body.
Cardiac failure, which leads to decreased cardiac output.
Systemic vascular resistance and heart rate affect cardiac output.
Stages of shock include compensated, decompensated, and multisystem organ failure.
Compensated shock: signs of poor perfusion; however, blood pressure (BP) is maintained.
Decompensated shock: worsening perfusion that leads to organ dysfunction and inability to maintain BP.
Multisystem organ failure: Perfusion is affected to the point that end-organ damage occurs. This damage can be irreversible in severe cases.
Etiology/Types
Multiple types including hypovolemic, distributive, and cardiogenic.
Caused by a variety of etiologies:
Congenital heart disease (CHD): ductal-dependent heart lesions, pulmonary hypertension, and postoperative state.
Arrhythmias: unrecognized supraventricular tachycardia, ventricular tachycardia, and bradycardia.
Drug toxicity: β-blockers, barbiturates, chemotherapy, radiation, and calcium channel blockers.
Cardiomyopathies and myocarditis.
Trauma: hemopericardium, pneumopericardium, and tamponade.
Metabolic abnormalities: hypocalcemia, hyperkalemia, and acidosis.
Pathophysiology
Pump failure: Poor systolic function leads to decreased cardiac output and decreased blood flow to the body. Initially, the body is able to increase stroke volume and heart rate to maintain cardiac output.
Infants are unable to increase their stroke volume adequately and are dependent on heart rate to maintain cardiac output.
Once compensatory mechanisms to maintain cardiac output are overwhelmed, the BP will drop, and the state of shock will progress.
Clinical Presentation
History: increased work of breathing, poor weight gain, difficulty breathing or diaphoresis with feeds, cyanosis, lethargy, and decreased number of urine output/wet diapers wet diapers.
Physical examination: tachycardia, tachypnea, cyanosis, cool, clammy, pale, or mottled extremities, prolonged capillary refill, decreased peripheral pulses, hepatomegaly, impaired mental status, oliguria, and lactic acidosis.
Hypotension (a late finding in shock of pediatric patients) in children is defined as a systolic BP <5th percentile for age.
<60 mmHg in term neonates (0-28 days of life);
<70 mmHg in infants (1-12 months of age);
<70 mmHg + (2 × age in years) in children 1 to 10 years of age;
<90 mmHg in children ≥10 years of age.
Patients with ductal-dependent heart lesions may present with hypoxia that is unresponsive to oxygen administration or signs of severe shock. They are dependent on the patent ductus arteriosus to supply pulmonary or systemic blood flow, and as it closes, adequate blood flow to either the lungs or body will not be maintained.
Diagnostic Evaluation
A clinical diagnosis; however, diagnostic evaluation is needed to determine etiology and aid in management.
Imaging: chest radiograph, ECG, echocardiogram.
Laboratory evaluation: complete blood count (CBC) with differential, electrolytes, glucose, calcium, magnesium, BUN, creatinine, blood gas with lactate, AST, ALT, PT, PTT, INR, and toxicology/drug screen.
Laboratory evaluation can assist in evaluating the degree of organ dysfunction secondary to shock as well as in identifying metabolic derangements that can be corrected with medical management.
Lactic acidosis develops due to decreased perfusion and development of anaerobic metabolism.
Management
Constant reassessment after each intervention for a change in BP, perfusion, urine output, and mental status.
First step in evaluating any patient should include airway, breathing, and circulation (ABCs).
Oxygen administration and/or intubation if respiratory compromise is present.
Intubation may be needed in severe shock in order to decrease afterload on the heart, thus reducing the workload of the heart.
Monitoring should include pulse oximetry, BP, and cardiorespiratory monitoring.
The second step is cautious fluid administration to increase preload.
In forms of shock other than cardiogenic, the patient should receive fluid boluses in increments of 20 mL/kg with an isotonic crystalloid fluid such as normal saline (0.9 NS) or lactated ringers (LR), administered as quickly as possible.
Fluid administration must be given cautiously in patients with cardiogenic shock. A large increase in preload may not be tolerated in patients with heart failure and may lead to overdistension of the heart, resulting in decreased cardiac output. This is described by the Frank-Starling Curve (see Figure 5.1).
The patient should be given fluid boluses in increments of 5 to 10 mL/kg with reassessment of clinical status after each fluid bolus.
If there is an inadequate response to fluid administration or the patient develops signs of worsening heart failure, the next step should be inotropic support with vasoactive medications.
TABLE 5.1 Common Vasoactive Medications
Dobutamine
Milrinone
Inotropic Agents (Dopamine, Epinephrine, Norepinephrine)
β-Adrenergic medication.
Increases contractility and promotes vasodilation.
Does not increase heart rate (chronotropic effect) as much as other vasopressor agents (e.g., dopamine and epinephrine). Increased heart rate decreases filling time and can further compromise cardiac output.
Dose: 2-20 mcg/kg/minute.
Phosphodiesterase enzyme inhibitor.
Reduces systemic vascular resistance (afterload) and increases contractility.
Can cause hypotension; use with caution in hypotensive patients.
Dose: 0.35-0.75 mcg/kg/minute.
Can be added if insufficient response to first-line therapy.
Use with caution in patients with cardiogenic shock due to the potential to increase systemic vascular resistance and further stress a failing ventricle.
FIGURE 5.1 • Frank-Starling Curve. Up to a point (the apex of the curve), cardiac myocytes contract with more force when stretched. Beyond that point, the fibers contract less forcefully.
Vasoactive medications improve contractility and reduce systemic vascular resistance, making it easier for the failing heart to pump (Table 5.1).
In infants < 1 month of age, ductal-dependent CHD should be considered.
Administration of prostaglandins (PGE1) at 0.05 to 0.2 mcg/kg/minute is necessary to maintain and/or open the ductus arteriosus.
Correct metabolic derangements and maintain normothermia.
Arrhythmias will require specific antiarrhythmic interventions including medications, cardioversion, and/or temporary pacing.
In case of cardiac tamponade, a pericardiocentesis is indicated to relieve the strain on the cardiac muscle.
Cardiogenic shock is a clinical diagnosis. Laboratory evaluation and imaging assist in determining underlying etiology and allow correction of metabolic derangements.
Goal of management is quick recognition and intervention with fluid resuscitation and inotropic support.
Once an intervention has been initiated, constantly reevaluate for improvement in clinical status or the need to escalate support.
PEARL
Recognize and intervene during compensated shock in order to prevent significant morbidity and mortality.
Cardiac Tamponade
Tageldin M. Ahmed
Background/Definition
Tamponade means compression.
Cardiac tamponade is defined as hemodynamically significant heart compression resulting from accumulation of fluid in the pericardial space.
The terms cardiac tamponade and pericardial tamponade are used interchangeably.
Etiology
Hemopericardium immediately after cardiac surgery; most common cause.
Penetrating and sometimes blunt trauma to the chest.
Viral or bacterial pericarditis.
Connective tissue diseases (e.g., systemic lupus erythematosus (SLE) and juvenile inflammatory arthritis [JIA]).
Oncological diseases/malignancies.
Uremia.
Pathophysiology
Pericardial sac is composed of fibrous tissue with limited capacity to stretch acutely.
Rapid accumulation of blood (e.g., trauma or post heart surgery), pus (e.g., infective pericarditis), or inflammatory fluid (e.g., rheumatologic, cancer, uremia) leads to impedance of heart filling during diastole.
Consequently, a small stroke volume is ejected with each heartbeat.
Ultimately, obstructive shock develops with loss of cardiac output.
Cardiac arrest ensues with characteristic pulseless electrical activity (PEA).
Clinical Presentation
Beck triad (classic):
Hypotension—from low cardiac output.
Distended neck (jugular) veins—from heart compression.
Muffled (distant) heart sounds—from fluid in pericardial space.
Pulsus paradoxus.
Narrow pulse pressure.
Pericardial rub.
Shock with tachycardia, tachypnea, and depressed mental status.
Diagnostic Evaluation
Echocardiogram is the diagnostic test of choice, demonstrating:
Effusion size and distribution.
Impaired diastolic heart filling.
Abnormal ventricular wall movement (Figure 5.2).
Chest radiograph:
Enlarged anterior mediastinum.
Globular heart shadow (cardiac silhouette).
ECG:
Low-voltage QRS complexes in all leads.
Abnormal ST segment.
Management
Cardiac tamponade is a medical emergency.
Needle pericardiocentesis is the emergent treatment of choice.
Fluid resuscitation, oxygen supplementation, and airway control are important adjuncts.
Further management depends on the etiology of the effusion resulting in tamponade.
Typically, a pericardial drainage tube (pigtail) or a pericardial window is created to prevent reaccumulation.
Treat the underlying disease process (e.g., infection).
Prevention.
Postoperative cardiac surgery patients often have mediastinal chest tube.
PEARLS
In trauma patients, hypotension refractory to fluid resuscitation should prompt suspicion of tamponade.
Hypotension with distended neck vein should always include tamponade in the differential diagnosis.
Cardiomyopathy
Caroline Bauer
Definition
Dilated cardiomyopathy.
A dilation of the left or both ventricles with impaired contraction/systolic dysfunction in the absence of an abnormal loading condition (e.g., hypertension, valvular disease, or coronary artery disease).
FIGURE 5.2 • Pericardial Effusion and Tamponade. A: The pericardial effusion and ventricular compression associated with cardiac tamponade are noted. B: Comparison of effusion during the pericardiocentesis and postpericardiocentesis.
Hypertrophic cardiomyopathy.
Hypertrophied, nondilated ventricle in the absence of a hemodynamic disturbance that is capable of producing the existent magnitude of wall thickening (e.g., hypertension, aortic valve stenosis, catecholamine secreting tumors, hyperthyroidism).
Restrictive cardiomyopathy.
Restrictive filling and reduced diastolic volume of either or both ventricles with normal to near normal systolic function and wall thickness.
Etiology
Dilated cardiomyopathy.
Idiopathic in approximately 50% of all pediatric cases.
Specific causes include inflammatory, genetic, congenital, viral, metabolic, autoimmune, or toxic etiologies.
Hypertrophic cardiomyopathy.
Idiopathic and familial in approximately 75% of cases.
Other etiologies include inborn errors of metabolism (9%), neuromuscular disorders (9%), and malformation syndromes (9%).
Restrictive cardiomyopathy.
One of the most rare forms of cardiomyopathy in children.
Almost never has an identifiable cause.
Annual incidence is 0.03/100,000 children.
Pathophysiology
Dilated cardiomyopathy.
Ability of the ventricle to pump blood is impaired and cannot maintain adequate cardiac output to meet the body’s demand.
Over time, the ventricles become progressively stiff and do not fill appropriately.
Results in a backup of blood into pulmonary circulation, which causes pulmonary edema, pulmonary hypertension, and atrial enlargement.
Hypertrophic cardiomyopathy.
The ventricles become thick and stiff, leading to impaired filling and the inability to meet the cardiac output demands of the body.
Over time, the ventricles become stiffer and can cause obstruction of blood flow out through the aorta.
Restrictive cardiomyopathy.
Leads to decreased filling compliance of the ventricles, causing severely elevated right atrial (RA) pressures and size.
The severely enlarged atrium can cause atrial arrhythmias (often difficult to control) as well as significant pulmonary hypertension.
Clinical Presentation
With all cardiomyopathies, the clinical presentation can vary, but may include:
Sudden cardiac death, chest pain (CP)/angina, syncope, palpitations.
Dyspnea, exercise intolerance.
Absence of symptoms.
Patients with severely impaired cardiac function will present with symptoms of heart failure and cardiogenic shock.
Physical Examination
New nondescript murmur, tachycardia, tachypnea, other signs of reduced cardiac output.
“Cardiac wheezing” is common with restrictive cardiomyopathy.
Patients are often initially misdiagnosed with asthma.
Diagnostic Evaluation
Chest radiograph.
ECG (Electrocardiogram).
Echocardiogram (see Figure 5.3).
Holter monitor to evaluate for life-threatening arrhythmias.
FIGURE 5.3 • Cardiomyopathy Echocardiogram Findings by Type. Representative single-frame echocardiograms demonstrating the salient features of the four types of cardiomyopathy seen in pediatric patients. A: Dilated cardiomyopathy, parasternal long axis view. Note the dilated left ventricular (LV) chamber and relatively thin LV posterior wall and septum. B: Hypertrophic cardiomyopathy, parasternal long axis view. Note the thickened LV posterior wall and septum and the small LV chamber size. C: Restrictive cardiomyopathy, apical four-chamber view. Note the markedly dilated right and left atria. D: LV noncompaction, apical four-chamber view.
Complete metabolic profile (CMP), (CMP evaluates for end organ function).
Other laboratory studies used to determine secondary causes of cardiomyopathy include:
Antinuclear antibodies (ANA); genetic/metabolic testing; inflammatory markers (e.g., C-reactive protein, tumor-necrosis-factor-α); viral panels; drug levels.
Management
Dilated cardiomyopathy.
Cardiorespiratory support.
Oxygen, ventilation (as indicated by patient clinical status), inotropic support, continuous telemetry.
Fluid management.
Cautious fluid resuscitation; volume overload can cause pulmonary edema and resultant respiratory failure.
Long-term medical therapies.
Afterload reducers, diuretics.
Extracorporeal support.
Ventricular assist devices (VAD), extracorporeal membranous oxygenation (ECMO).
Heart transplantation; may be required for severe cardiac dysfunction.
Hypertrophic cardiomyopathy.
Inotropic support can worsen systolic function and increase obstruction, and should be avoided.
β-Blockers: provide rate control and reduce symptoms of CP and palpitations.
Calcium channel blockers can be used for angina and to improve diastolic function.
Dehydration can worsen obstruction and decrease cardiac output, so should be avoided.
Volume status should be carefully monitored to avoid fluid overload, but provide adequate preload to the heart.
In failed cases of traditional medical therapy with β-blockers, other treatments include myomectomy
(e.g., surgical removal of excess muscle from the heart), pacemaker implantation, and septal ablation may be considered.
Asymptomatic individuals should be carefully monitored by a cardiologist; however, may not require any treatment until symptomatic.
Restrictive cardiomyopathy.
No proven therapies currently exist.
Anticoagulation is recommended.
High risk of sudden embolic events.
β-Blockers, angiotensin-converting enzyme inhibitors, diuretics, and pacemakers may be helpful, but none of these therapies are evidence-based.
VAD or ECMO may be necessary for cardiopulmonary support or as a bridge to transplantation.
The definitive treatment is a heart transplant.
Should be considered early as pulmonary hypertension is a contraindication to transplant.
Consultations: cardiology, cardiothoracic surgery, genetics, and infectious disease.
PEARL
All patients with cardiomyopathy, regardless of type or severity, require restriction from competitive sports.
Chylothorax
Jennifer L. Joiner
Background
Disruption of the lymphatic drainage from damage or obstruction that results in an accumulation of pleural chest fluid, leading to chylous pleural effusion with resulting respiratory distress.
Most commonly found in posttraumatic or postsurgical patients.
Definition
Accumulation of chyle fluid that is found between the visceral and parietal pleural space.
Overproduction of chylus fluid overwhelms the resorptive abilities of the lymphatic system.
When damage or blockage has occurred in lymphatic drainage and a pleural effusion develops.
Etiology/Types
Postsurgical/traumatic.
Congenital.
Spontaneous.
Oncologic/malignancy.
Clinical Presentation
Depends on the degree of the effusion.
Larger effusions result in tachypnea, hypoxia, increased work of breathing, respiratory distress, or respiratory failure.
Most often suspected in children with risk factors, demonstrating a pleural effusion on chest radiograph.
Milky-appearing pleural fluid, if ingesting enteral fat; may be serous if on nonfat nutrition or total parenteral nutrition (TPN).
Diagnostic Evaluation
Decubitus or lateral chest radiograph (CXR).
Ultrasound of chest; evaluates presence, size, and location of fluid collection.
Pleural fluid evaluation (confirmatory).
Triglyceride level >110 mg/dL.
Presence of chylomicrons.
Predominately lymphocytic; white blood cell count (WBC) >1,000 × 103/µL.
Management
Larger effusions causing respiratory compromise require a thoracostomy tube and respiratory support.
Strict dietary fat restriction for 3 to 6 weeks with supplementary fat provided by intralipids or a medium chain transfat (MCT) oil containing formula.
Diuretics have been used as adjunctive therapy.
Octreotide has been used in postoperative cardiac patients with mixed results.
Pleurodesis or ligation of the thoracic duct must be considered in cases refractory to medical management.
PEARL
Infants/children with chylothorax should receive feedings with medium chain transfat (MCT).
Congenital Heart Disease
Julie A. Creaden
Elizabeth R. Preze
Acyanotic Lesions
Patent Ductus Arteriosus (PDA)
Background/Definition
Vascular communication between the left pulmonary artery (PA) and the descending aorta (Figure 5.4).
Pathophysiology
Anatomy of PDA can differ if associated with other cardiac lesions.
Typically, closes within first 12 to 24 hours of life.
Clinical Presentation
Systolic murmur left sternal border (LSB) (neonates).
Continuous murmur left upper sternal border (LUSB) (older children).
Bounding pulses.
Widened pulse pressure with low diastolic pressure.
 FIGURE 5.4 • Patent Ductus Arteriosus. A: Normal. B: The ductus arteriosus fails to close. |
Diagnostic Evaluation
Chest radiograph: prominent main PA with increased pulmonary vascular markings (PVM), cardiomegaly.
Electrocardiography (ECG): left atrial (LA) enlargement and biventricular hypertrophy.
Echocardiogram (ECHO): usually sufficient for diagnosis.
Management
Medical management:
Nonsteroidal anti-inflammatory drugs (NSAIDS): Indomethacin or a special intravenous (IV) form of ibuprofen has been used to help close a PDA; especially viable alternative for premature infants. Contraindicated in infants with intraventricular hemorrhage (IVH).
Surgical management: Surgical intervention required if PDA remains open past 3 months of age. Typically performed in the first 6 months of life. Surgical ligation and division through a left thoracotomy incision or via video-assisted thoracoscopic surgery (VATS).
Cardiac catheterization intervention: coil embolization used to occlude PDA.
Postprocedural considerations:
Surgical complications: recurrent laryngeal nerve damage, recurrence of patency of PDA, chylothorax, ligation of unintended vessel (e.g., aorta, left PA or left main stem bronchus, bleeding, infection).
Postcardiac catheterization complications: coil migration, bleeding, residual shunt.
Postoperative checklist:
Review chest radiograph for common intrathoracic problems.
Evaluate pulses to support ligation of PDA rather than nonductus vascular structures (e.g., aorta or LPA).
Monitor for bleeding or infection.
Postcardiac catheterization checklist:
Monitor catheter site for bleeding, hematoma, or infection.
Monitor distal pulses and perfusion from catheter site.
Auscultate for murmurs.
Follow postcardiac catheterization protocol (bed rest, keep leg straight) per institutional policy or provider order.
Chest radiograph/ECHO to visualize coil placement.
Atrial Septal Defect (ASD)
Background/Definition
Communication between the atria (see Figure 5.5).
Three types of ASDs:
Ostium secundum: most common type; occurs in the center of the septum.
Ostium primum: occurs low in the septum; may involve atrioventricular valve abnormalities and mitral insufficiency.
Sinus venosus: occurs high in the septum near the superior vena cava (SVC) and RA junction; can be associated with partial anomalous pulmonary venous return (PAPVR).
 FIGURE 5.5 • Atrial Septal Defect. In an atrial septal defect, an abnormal communication exists between the atria, allowing blood to be shunted from the left atrium to the right atrium through the atrial septum. |
Pathophysiology
Left-to-right shunting occurs in ASDs.
Degree of shunting depends on the size of the ASD.
Nonrestrictive: equal pressure in both atria; shunting is determined solely by ventricular compliance.
Restrictive: size of the defect is small enough to provide resistance to flow.
Compliance of the ventricles.
Shunting increases with age as ventricle becomes more compliant.
Clinical Presentation
Physical examination:
Systolic ejection murmur LUSB.
Widely split S2.
Diagnostic Evaluation
Chest radiograph: cardiomegaly with increased PVM.
Electrocardiography: R-axis deviation with right ventricular hypertrophy (RVH) and right bundle branch block (RBBB) pattern.
Echocardiogram: sufficient for diagnosis; can miss associated PAPVR.
Cardiac catheterization: not indicated unless suspicion of coexisting lesion or pulmonary hypertension.
Management
Surgical management:
Recommend closure between 3 to 5 years of age.
Spontaneous closure of small secundum defects occurs in 87% of infants during the first year of life.
Mortality in most centers with uncomplicated cases approaches 0%.
Repaired using a pericardial or prosthetic patch or direct suture closure.
Cardiac catheterization intervention.
Transcatheter closure commonly used to close ostium secundum ASDs in the cardiac catheterization lab.
ASD must be <22 mm in size and have an inferior rim for the device to safely attach.
Postoperative Considerations
Sinoatrial (SA) node dysfunction: direct trauma or interruption of blood supply.
Postpericardiotomy syndrome: fever, malaise, lymphocytosis, nausea, vomiting, abdominal pain, pericardial effusion; usually occurs approximately 14 days postop.
Left ventricular (LV) dysfunction: more common in older children with chronic right ventricular (RV) dilation.
Pulmonary hypertension: uncommon in children; increases risk for mortality.
Residual ASD.
Venous obstruction: following repair of sinus venosus (SVC or PV stenosis) ASD.
Monitor for signs of pericardial effusion, sinus node dysfunction, and signs of noncompliant left ventricle (older patients).
Postcardiac Catheterization Considerations
Bleeding and infection from access site.
Catheter migration/displacement.
Monitor catheter access site post catheterization, bed rest.
Ventricular Septal Defect (VSD)
Background/Definition
Communication between the right and left ventricles (see Figure 5.6).
May occur in isolation or with other associated defects.
Most common; accounts for approximately 50% of congenital heart defects.
Four different types of VSDs:
Perimembranous: opening in the upper portion of the ventricular septum.
Most common type of VSD; does not usually close on its own.
Outlet type (subarterial): opening in the septum is just below the pulmonary valve in the ventricular septum.
Inlet type (canal): opening is just below the AV valves (tricuspid and mitral) in the ventricular septum.
Can be associated with atrioventricular canal (AVC) defect.
Muscular: an opening in the muscular portion of the lower ventricular septum. Many of these VSDs close spontaneously, and do not require surgery.
Pathophysiology
Left-to-right shunting at ventricular level.
Degree of shunting depends on the size of the VSD.
Nonrestrictive: no pressure gradient between the ventricles; shunting is determined by pulmonary vascular resistance (PVR).
FIGURE 5.6 • Ventricular Septal Defect. In a ventricular septal defect, a hole is in the wall of the septum that separates the left and right ventricles. Normally, deoxygenated blood flows through the superior vena cava and inferior vena cava into the right atrium, right ventricle, and pulmonary artery. In a ventricular septal defect, some oxygen-rich blood from the left ventricle flows through the defect and recirculates through the lungs. Note the thickened LV myocardium and deep trabeculations indicated by the arrows.
Restrictive: size of the defect is smaller than the aortic root diameter, degree of shunting is determined by the size of the defect.
PVR (PVR is delayed in neonates with VSDs).
Clinical Presentation
Physical examination: harsh holosystolic murmur at LSB; may have thrill and/or middiastolic rumble at apex.
Chest radiograph: enlarged left atrium (LA) with prominent main PA.
Electrocardiography: biventricular or left ventricular hypertrophy (LVH).
Echocardiogram: typically sufficient for diagnosis.
Cardiac catheterization: used to quantify degree of left (L) to right (R) shunt in a moderate-sized defect; may be used if pulmonary hypertension is suspected.
Management
Medical management:
Perimembranous and muscular VSDs can be observed (up to one year of age) as spontaneous closure is possible.
Inlet or malaligned septum VSDs will not close spontaneously.
Once PVR decreases, symptoms of failure to thrive (FTT) and congestive heart failure (CHF) will develop in infants with VSD.
Treat symptoms of FTT and CHF until surgery is recommended.
Surgical management:
Timing based on size and location of the defect and degree of FTT and CHF.
Typically, surgery is done within the 1st year of life.
Mortality <5%; higher in children with multiple muscular VSDs.
Surgical repair:
Requires median sternotomy and cardiopulmonary bypass.
Repair of VSD includes: Closure of VSD with prosthetic patch material (Dacron), tanned pericardium (treated with glutaraldehyde), or suture closure; frequent use of pledgeted suture technique; multiple muscular VSDs may require PA banding (difficult to approach surgically).
Postoperative Considerations
Residual VSD.
Pulmonary hypertension; delayed closure and large defects are at most risk.
Heart block (transient or permanent).
Junctional ectopic tachycardia (JET).
Monitor for pulmonary hypertension and evaluate for residual VSDs in a timely manner; if signs of low cardiac output, consider residual VSD or additional undiagnosed defect.
Atrioventricular Canal (AVC)
Background/Definition
Defect resulting from nonfusion of the endocardial cushion.
Three components: ostium primum ASD; inlet VSD; Abnormal formation of AV valves (see Figure 5.7).
Three types:
Partial: ostium primum defect associated with a cleft in the anterior mitral valve (two separate AV valves); no VSD.
Transitional: ostium primum defect with AV valves only partially separated into two valves; has VSD but may be small.
Complete: ostium primum defect with large nonrestrictive VSD and a single AV valve; Three subtypes are recognized (Rastelli types A, B, and C).
Unbalanced AV canal.
Hypoplasia of either right or left ventricle.
Pathophysiology
Partial form: resembles ASD unless severe AV valve regurgitation is present.
Complete form: resembles VSD with an associated ASD; biatrial and biventricular volume overload; AV valve regurgitation worsens ventricular volume overload.
Clinical Presentation
Diagnostic Evaluation
Chest radiograph: cardiomegaly with increased pulmonary vascular markings.
Electrocardiography: left axis deviation, biatrial and biventricular hypertrophy.
Echocardiogram: used to diagnose and type by closely evaluating AV valves.
Cardiac catheterization: usually not indicated unless echocardiogram is not sufficient in defining AV valve morphology.
Management
Surgical management:
Partial AV canal: repaired at 1 to 5 years of age; earlier if left AV valve regurgitation is present.
Complete AV canal: repaired at 3 to 6 months of age.
Morbidity/Mortality:
Partial AV canal: 5% mortality; If AV valve regurgitation 10%.
Complete AV canal: 10% in the first year of life.
Surgical repair: requires median sternotomy and cardiopulmonary bypass; approach via right atriotomy; one- or two-patch technique may be used.
PA band: recommended only in specific situations (e.g., severe illness, unbalanced defects).
Postoperative Considerations
Goals following surgical repair: aim for lower filling pressure; liberal inotropic support; minimize volume loading (exacerbates AV valve regurgitation).
High incidence of postoperative pulmonary hypertension; correlated with older age at time of surgical repair.
Low cardiac output.
Elevated LA pressure.
Heart block; up to 10% incidence.
Residual VSD.
Junctional ectopic tachycardia (JET).
Following repair, AV valves will never be normal; long-term follow-up is essential.
Hemodynamic deterioration anytime after repair is considered severe left AV valve regurgitation until proven otherwise.
Cyanotic Lesions
Julie A. Creaden
Elizabeth R. Preze
Tetralogy of Fallot (TOF)
Pathophysiology
Dependent on degree of pulmonary stenosis.
Too much pulmonary blood flow “pink TET.”
L→R shunt with CHF and pulmonary overcirculation.
Too little pulmonary blood flow.
R→L shunt with hypoxia (SaO2 70%-80%).
Balanced circulation.
Have mild hypoxia (SaO2 ˜ 90%) and are relatively asymptomatic.
Clinical Presentation
Hypercyanotic (TET) spells:
Involves agitation/irritability, profound cyanosis, syncope.
Can lead to severe disability and even death.
Physical examination:
Harsh systolic ejection murmur (SEM) at upper sternal border (USB).
Cyanosis of lips and nail beds.
Diagnostic Evaluation
Electrocardiography: right axis deviation with RVH.
Chest radiograph: Boot-shaped heart with either increased or decreased pulmonary blood flow (see Figure 5.9).
Echocardiogram: Primary diagnostic modality.
 FIGURE 5.8 • Tetralogy of Fallot. Tetralogy of fallot defect. |
 FIGURE 5.9 • Chest Radiograph TOF. Tetralogy of Fallot. The upwardly displaced cardiac apex caused by right ventricular hypertrophy and the concave pulmonary artery shadow are characteristic of Tetralogy of Fallot. |
Management
Medical management:
Asymptomatic
β-blocker agent
Neonatal period to 1 year of age
Symptomatic/TET spells—believed to be caused by infundibular muscle spasms, resulting in right-to-left shunting through the VSD.
Treatment includes supplemental oxygen, sedation, volume expansion, knee-chest position.
In severe cases, may require phenyl epinephrine, emergency surgery, and/or extra corporeal membrane oxygenation (ECMO).
Surgical interventions:
Blalock-Taussig (BT) shunt made of Gore-Tex (W.L. & Associates, Flagstaff, AZ) connecting the subclavian or carotid artery with the PA to allow blood flow to the branch pulmonary arteries with subsequent complete repair before 1 year of age, or
Complete repair in the neonatal period.
Placement of BT shunt ± CPB (cardiopulmonary bypass), depending on the severity of right ventricular outflow tract (RVOT) obstruction.
Complete repair consisting of right atriotomy, closure of VSD, resection of infundibular stenosis, pulmonary arterioplasty, pulmonary valvotomy, or transannular right ventricular outflow tract (RVOT) patch.
Postoperative Checklist
Evaluate for residual VSD and RVOT obstruction and dysfunction.
Continuous monitoring of heart rate with evaluation for arrhythmia (e.g., JET, ventricular ectopy).
Temporary pacemaker available at bedside, in some cases.
In neonates with BT shunt, consider shunt occlusion with desaturation.
Pulmonary Atresia
Pulmonary atresia with intact ventricular septum.
Background/Definition
Variable morphology.
Obstruction of RVOT due to pulmonary valve atresia, intact ventricular septum and variable hypoplasia of right ventricle (RV) and tricuspid valve.
Patients with small RVs and tricuspid valve annulus may also have coronary artery sinusoids and fistulae.
If present, they will greatly determine surgical management strategies (Figure 5.10).
Pathophysiology
Similar to other single ventricle physiology.
Desaturation level dependent on size of PDA.
Atrial level shunting helps preserve cardiac output in the setting of a patent ductus.
Arterial oxygen saturation serves as a good estimate of pulmonary to systemic blood flow ratio.
RV may have very high pressures during systole.
Clinical Presentation
Progressive cyanosis with ductal closing causing profound hypoxemia, acidosis, and hemodynamic collapse.
Systolic murmur of ductal flow, single first and second heart sounds.
Diagnostic Evaluation
Chest radiograph:
Normal heart size unless significant tricuspid regurgitation (TR) is present, then right atrium (RA) and RV enlargement are present.
Pulmonary vascular markings (PVM) are dependent on size of PDA and PVR.
Electrocardiogram:
Diminished RV force.
Dominant LV forces.
Echocardiography:
Sufficient to establish basic diagnosis.
RV size and function, tricuspid valve size and function, atrial level shunting and PDA flow are all easily evaluated.
Abnormal flow patterns in the RV are suggestive of coronary artery fistulae or sinusoids.
FIGURE 5.10 • Pulmonary Atresia with Intact Ventricular Septum. Pulmonary atresia (PA) with intact ventricular septum (IVS) in a neonate with a nonrestrictive patent ductus arteriosus while receiving PGE1. Typical anatomic and hemodynamic findings include (i) hypertrophied, hypoplastic right ventricle; (ii) hypoplastic tricuspid valve and pulmonary annulus; (iii) atresia of the pulmonary valve with no antegrade flow; (iv) suprasystemic RV pressure; (v) pulmonary blood flow through the patent ductus; (vi) right-to-left shunt at the atrial level with systemic desaturation. Many patients have significant coronary abnormalities with sinusoidal or fistulous connections to the hypertensive right ventricle or significant coronary stenoses (not shown). Prostaglandin E1 (PGE1), mean value (m).
Cardiac catheterization:
Should always be performed with echocardiogram to conclusively define coronary anatomy.
Surgical Management
Because of variable morphology, no single procedure is appropriate for all patients.
Goals of initial surgery.
Provide adequate oxygenation.
Provide forward flow across RVOT to encourage RV development; ultimate goal is two-ventricle repair.
Timing of surgery is in neonatal period.
Surgical Requirements
Patients with right ventricular dependent coronary circulation (RVDCC)—single ventricle pathway.
Palliative BT shunt.
Will then go on to have either Glenn and Fontan or a 1½ ventricular repair.
Patients without RVDCC.
Relief of RVOT obstruction with or without a BT shunt.
Ultimately, will have a two-ventricle repair.
Patients with severe RVDCC and evidence of LV dysfunction, ischemia, or arrhythmias, consider for transplantation.
Z-score (includes echocardiogram measurements and body surface area) of the tricuspid valve size significant in determining risk of biventricular repair success.
Postoperative Complications
Similar to problems in the management of single ventricle physiology.
Low cardiac output.
Immediate—unrecognized RVDCC with myocardial ischemia.
1 to 3 days postoperative – circular shunt (pulmonary insufficiency [PI], tricuspid insufficiency [TI], ASD).
Treatment: Increase PVR and decrease systemic venous return (SVR).
Hypoxemia; evaluate for:
Residual RVOT obstruction, or
Severe tricuspid valve (TV) hypoplasia.
Postoperative Checklist
In shunt-dependent patients, balance circulation.
Monitor for signs of ischemia with 12-lead ECG and/or echocardiogram.
Evaluate for signs of low cardiac output and “circular shunting.”
Tricuspid Atresia
Background/Definition
Complete lack of formation of the tricuspid valve with absence of direct connection between the RA and RV (see Figure 5.11).
Three types based on relationship of great arteries to ventricle.
Type I: normally related great arteries.
Type II: D-transposition.
Type III: L-transposition.
Pathophysiology
Two subclasses based on amount of pulmonary stenosis and presence of VSD:
Too little pulmonary blood flow.
Too much pulmonary blood flow.
Clinical Presentation
Physical Examination.
Cyanosis or CHF.
80% will have murmur.
Too much pulmonary blood flow.
Too little pulmonary blood flow (SaO2 <70%).
Management
Treatment is tailored to underlying anatomy or pathophysiology.
FIGURE 5.11 • Triscuspid Atresia.
Intracardiac obstruction.
Increase BP or SVR with inotropes.
Cardiac catheterization manipulation: Atrial septectomy with restrictive ASD.
Restrictive ductus arteriosus in ductal-dependent lesions.
PGE1 infusion.
Elevated PVR.
Maneuvers to decrease PVR—increase FiO2, hyperventilation, alkalinization, nitric oxide, analgesia/sedation.
Too much pulmonary blood flow.
Digitalis and diuretics.
Diagnostic Evaluation
Electrocardiogram:
RA enlargement, possible first degree heart block.
Chest radiograph:
Cardiomegaly.
PVM may be increased or decreased depending on the presence of VSD and degree of pulmonary stenosis.
Echocardiogram:
Sufficient for diagnosis.
Can determine basic anatomy.
Size and/or presence of an ASD and VSD.
Relationship of the great vessels.
Degree of pulmonary blood flow.
Ventricular function.
Cardiac catheterization:
Indicated when a restrictive atrial septal defect (ASD) is present.
If ASD present, balloon septostomy can be performed.
Management
Surgical Timing:
May not require surgical intervention until symptomatic (in 1st year of life).
Cyanosis with decreased pulmonary blood flow/ductal-dependent lesion.
CHF with increased pulmonary blood flow (PBF) (VSD without PS).
No definitive repair, staged approach.
Surgical procedure: Stage 1.
Decreased pulmonary blood flow (most common).
BT shunt.
Increased pulmonary blood flow.
PA band (PAB).
Surgical procedure: Stage 2 bidirectional Glenn.
4 to 12 months of age.
Procedure involves:
Disconnecting superior vena cava (SVC) from RA and connecting SVC directly to right pulmonary artery (RPA).
Ligation and division of modified Blalock-Taussig Shunt (MBTS).
Surgical procedure: Stage 3 Fontan procedures.
18 months to 4 years of age.
Fontan procedures:
Lateral tunnel: Inferior vena cava flow is directed into the RPA via a lateral tunnel created through the RA using a Gore-Tex patch.
Fenestrations may be placed in the patch to act as a “pop off” until the pulmonary circulation can handle the circulating volume.
Extracardiac: insertion of a Gore-Tex tube graft connecting the inferior vena cava (IVC) to the underside of the RPA.
Ductal-Dependent Lesions
Julie A. Creaden
Elizabeth R. Preze
Hypoplastic Left Heart Syndrome (HLHS)
Background/Definition
Most common form of single ventricle physiology.
Ductal-dependent lesion requiring urgent surgical intervention.
Characterized by hypoplasia of the LV, and encompasses atresia or critical stenosis of the aortic and/or mitral valves and hypoplasia of the ascending aorta and aortic arch (see Figure 5.12).
Presents at birth with cyanosis.
Pathophysiology
Systemic circulation is dependent on the RV via the PDA and mixing of pulmonary and systemic blood at the atrial level.
Patent foramen ovale is typically present, but can be small and obstructive.
FIGURE 5.12 • Hypoplastic Left Heart Syndrome.
Blood from the pulmonary veins cannot get into the diminutive LV and therefore mixes with systemic venous return in the right atrium.
The RV pumps mixed blood to both pulmonary and systemic circulations via the PDA.
Blood is sent to the lungs via the branch pulmonary arteries and the body via the PDA.
The amount of blood that flows to each circulation is based on the resistance in each circuit.
Physical Examination
Single S2.
Soft systolic murmur.
Diagnostic Evaluation
Electrocardiogram:
Right atrial enlargement (RAE).
Right ventricular hypertrophy (RVH).
Chest radiograph:
Cardiomegaly and increased PVM.
Echocardiogram:
Determination of cardiac morphology.
Evaluation of arch hypoplasia.
Diminutive LV with markedly dilated RV with aortic hypoplasia.
Determines the size of ASD and/or VSD and the degree of shunting across the septal defect(s).
Cardiac catheterization:
Rarely necessary for diagnosis.
Helpful in establishing atrial communication via balloon septostomy.
Management
Goal is to balance circulations!
Excessive pulmonary blood flow (SaO2 >90%).
Results in reduction of systemic blood flow.
Despite higher oxygen saturation, tissue perfusion is actually compromised.
Treatment
Maintain PDA patency with PGE1 infusion or atrial septostomy (restrictive ASD).
Maneuvers to increase PVR and decrease SVR.
Alveolar hypoxia (FiO2 0.21 or lower using nitrogen blend).
Permissive hypercarbia (pH 7.30-7.40 with PaCO2 45-50 mmHg).
Afterload reduction (e.g., milrinone, nipride).
Minimize inotropic agents, particularly those with alpha effects.
Surgical Management
Diagnosis usually occurs in the antenatal or immediate postnatal period and requires timely intervention.
Stage 1 Norwood procedure.
Goals are to:
Establish reliable, unobstructed outflow to the systemic circulation, and
Balance the systemic and pulmonary circulations.
Components:
Placement of modified Blalock-Taussig shunt and ligation and division of PDA or Sano modification = placement of 5 mm Gortex shunt from the RV to PA bifurcation.
Division of main pulmonary artery (MPA) proximal to bifurcation to the branch pulmonary arteries.
Augmentation of the hypoplastic aortic arch with prosthetic material or homograft.
Connection of proximal PA to ascending aortic arch.
Atrial septectomy.
Postoperative management: Stage 1 Norwood.
Balance the systemic and pulmonary circulations with SaO2 75% to 80%.
Monitor for pulmonary overcirculation.
Elevated O2 saturations, hypotension, tachycardia, oliguria, metabolic acidosis.
Aspirin to avoid shunt thrombosis.
Monitor for signs and symptoms of necrotizing enterocolitis (NEC).
Postoperative problems: Stage 1 Norwood.
Low cardiac output.
Globally decreased ventricular output.
Elevated Qp:Qs (pulmonary to systemic flow ratio).
AV valve regurgitation.
Cyanosis (SaO2 <70%).
Pulmonary venous desaturation.
Systemic venous desaturation.
Decreased pulmonary blood flow.
Elevated oxygen saturations (SaO2 >90%).
Too much pulmonary blood flow.
Evaluate for presence of arch obstruction (increases pulmonary blood flow through BT shunt).
Stage 2 bidirectional Glenn procedure.
Usually done between 4 and 6 months of age.
Provides reduced volume work on the single ventricle and a predictable Qp:Qs 0.6 to 0.7 with oxygen saturations of approximately 80%.
Procedure involves:
Disconnecting SVC from RA and connecting SVC directly to RPA.
Ligation and division of MBTS or Sano shunt.
Postoperative problems: Stage 2 bidirectional Glenn.
Headache.
Elevated SVC pressure (SVC syndrome).
Obstruction at anastomosis.
Distal PA distortion.
Elevated PVR.
Hypoxemia (SaO2 <75%).
Pulmonary venous desaturation.
Systemic venous desaturation.
Decreased pulmonary blood flow.
Hypertension/bradycardia.
Stage 3 Fontan procedure.
Stage 3 usually occurs at 18 months to 4 years of age.
Fontan procedure components.
Lateral tunnel: Inferior vena cava flow is directed into the RPA via a lateral tunnel created through the RA with a Gore-Tex patch.
Fenestrations may be placed in the patch to act as a “pop off” until the pulmonary circulation can handle the circulating volume.
Extracardiac: insertion of a Gore-Tex tube graft connecting the IVC to the underside of the RPA.
Postoperative management: Stage 3 Fontan.
Goal is to optimize cardiac output at lowest central venous pressure (CVP) possible.
Low positive end expiratory pressure (PEEP) on mechanical ventilation.
Attempt early extubation.
Aggressively treat arrhythmias.
Junctional ectopic tachycardia (JET) and atrial tachycardia—amiodarone.
Pacing; in cases of sinus node dysfunction.
Postoperative problems: Stage 3 Fontan.
Low cardiac output.
Inadequate preload.
Elevated PVR.
Anatomic systemic venous pathway obstruction.
Pump failure.
Arrhythmias.
Cyanosis.
Effusions.
Most common cause of prolonged hospitalization.
Thrombosis.
At risk of venous thrombosis and cerebellar nuclei neurons (CNS) complications.
Anticoagulation (e.g., warfarin, aspirin).
Transposition of the Great Arteries (TGA)
Complete transposition of the great arteries (D-TGA).
Background/Definition
Aorta arising from the anatomic RV, and the PA arising from the anatomic left ventricle.
May have associated VSD (40% of cases).
Ventricles normally positioned and aorta malposed anteriorly and rightward above the RV, aligned with the RV via the infundibulum (Figure 5.13).
Pathophysiology
Parallel circulation.
The output from each ventricle is recirculated to that ventricle.
Results in a deficiency of oxygen supply to the tissues and excessive ventricular workload.
Systemic and pulmonary oxygen saturations are dependent on:
Intracardiac shunts (PFO, ASD, VSD).
FIGURE 5.13 • Transposition of Great Arteries.
Extracardiac shunts (PDA, bronchopulmonary collaterals).
Clinical Presentation
Physical examination.
Soft systolic murmur.
Bounding peripheral pulses related to the PDA.
Hepatomegaly.
Hypoxemia.
Initial management includes ensuring adequate mixing and maximizing mixed venous oxygen saturation (SVO2).
Ensure adequate mixing.
Maintain PDA patency with PGE1 infusion.
If no improvement with PGE1 infusion, consider balloon septostomy.
Institute ventilatory maneuvers to decrease PVR and increase PBF.
Maximize SVO2.
Decrease O2 consumption.
Improve O2 delivery.
Diagnostic Evaluation
Echocardiogram:
A posterior great artery diving to the left and right pulmonary arteries arising from the LV along with the aorta arising from the RV confirm the diagnosis.
Cardiac catheterization:
Useful for evaluation of coronary artery anatomy.
Enlargement of atrial septum, if needed.
Management
Arterial switch ± VSD closure.
Timing.
Neonatal period.
Surgical requirements.
Cardiopulmonary bypass (CPB) with deep hypothermia and circulatory arrest.
Arterial switch.
Transection of the great vessels.
Translocation of the coronary arteries.
Aortic reconstruction.
Pulmonary reconstruction.
Closure of ASD or VSD.
Postoperative Complications
Arrhythmias.
Coronary ischemia.
LV dysfunction.
Coronary ischemia.
“Unprepared” LV.
Noncompliant LV.
Postoperative checklist
Evaluate LV function, for arrhythmias, supravalvar aortic stenosis (AS), pulmonary stenosis, residual ASD, or VSD by ECHO.
Total Anomalous Pulmonary Venous Return (TAPVR)
Background/Definition
Pulmonary veins drain anomalously into a systemic venous structure rather than into the left atrium LA.
Can be total (all pulmonary veins—TAPVR) or partial anomalous drainage (partial anomalous pulmonary venous return [PAPVR]).
TAPVR has three main types:
Supracardiac.
Pulmonary veins drain into the SVC.
Intracardiac.
Pulmonary veins drain into coronary sinus or RA.
Infracardiac.
Pulmonary veins drain into a common pulmonary vein→ portal system→IVC via the ductus venosus.
Pathophysiology
Obstructed.
Pulmonary venous hypertension with resultant pulmonary edema.
Infracardiac most likely to be obstructive.
Unobstructed.
Right-sided heart failure due to volume overload.
Clinical Presentation
Dependent on degree of obstruction to pulmonary venous drainage and degree of obstruction to the compensatory right-to-left shunt.
Obstructed veins will present immediately with hypoxia, severe cyanosis, hypotension, and metabolic acidosis—this is one of the few cardiac surgical emergencies requiring emergent surgical intervention.
Unobstructive veins may go undetected for a short while, but eventually present with increased work of breathing and notable murmur—loud continuous split S2 together with a systolic ejection murmur over the pulmonary valve.
Hepatomegaly, venous congestion.
Diagnostic Evaluation
Chest radiograph:
Obstructed: pulmonary edema without cardiomegaly (see Figure 5.14).
Unobstructed: increased PVM with cardiomegaly.
Electrocardiography:
RA and RV hypertrophy.
Echocardiogram:
Difficult to diagnose with transthoracic echocardiogram
Cardiac catheterization:
Usually not indicated; avoid with obstructed veins
MRI/MRA:
Becoming more widely used to diagnose TAPVR/PAPVR.
Management
Surgical intervention—emergent if obstructed.
Requires median sternotomy and cardiopulmonary bypass.
Includes anastomosing the pulmonary veins to the LA and closure of ASD.
Postoperative Complications
Low cardiac output.
Respiratory insufficiency.
FIGURE 5.14 • Chest Radiograph TAPVR with Obstructed Veins. Chest X-ray demonstrating diffuse interstitial pulmonary edema and a normal cardiac silhouette in a patient with obstructed total anomalous pulmonary venous return.
Pulmonary hypertension.
Dysrhythmias.
Pulmonary vein stenosis; usually appears in the first 6 to 12 months after repair; presents when obstruction is severe; clinical signs are progressive shortness of breath and requires additional surgical intervention.
Postop Checklist
Monitor for pulmonary hypertension.
Suspect pulmonary venous obstruction if present.
Be aware of decreased left-sided compliance and avoid aggressive volume.
Truncus Arteriosus (TA)
Background/Definition
Congenital malformation, which is a single arterial trunk arising from the heart: results from failure of the truncus arteriosus to divide into the aorta and PA.
Almost always associated with a VSD.
All conotruncal lesions are associated with 22q11 deletion.
Uses site of origin of pulmonary arteries from the truncus to define types
Type I to III are true truncus.
Type IV more accurately considered pulmonary atresia (Figure 5.15).
Pathophysiology
Resembles single ventricle physiology.
FIGURE 5.15 • Truncus Arteriosus.
Degree of pulmonary blood flow is dependent on PVR and the degree of pulmonary stenosis.
In the absence of pulmonary stenosis, the fall in PVR leads to pulmonary overcirculation and symptoms of CHF.
Congestive heart failure is exacerbated in the presence of truncal valve regurgitation.
Small PA from the truncus offers resistance to pulmonary blood flow (PBF), resulting in small Qp (pulmonary blood flow) and low oxygen saturation.
Mild narrowing of PA from the truncus offers mild resistance to pulmonary blood flow, resulting in equal Qp and Qs (pulmonary and systemic blood flow) with acceptable oxygen saturation.
Normal size PA from the truncus offers no resistance to pulmonary blood flow, resulting in high Qp:Qs and high oxygen saturation. Pulmonary edema and CHF will be present.
Clinical Presentation
Physical examination:
Signs of CHF: tachypnea, hepatomegaly, diaphoresis (e.g., sweating with feeds), FTT, bounding pulses.
Harsh systolic murmur with possible ejection click—diastolic murmur present if truncal valve insufficiency or regurgitation.
Diagnostic Evaluation
Electrocardiography:
Normal sinus rhythm (NSR).
Biventricular hypertrophy.
Chest radiograph:
Cardiomegaly.
Increased pulmonary vascular markings.
Absent PA segment.
Echocardiogram:
Provides good information to determine type of truncus arteriosus.
Demonstrates origin of coronary arteries, character of the truncal valve and truncal valve insufficiency—usually quadricuspid.
Computed tomography (CT)/magnetic resonance imaging (MRI) and cardiac catheterization can be helpful in determining coronary anatomy, truncal valve insufficiency, and in measuring PVR.
Management
Early surgical intervention before decompensated CHF, increased pulmonary vascular resistance, or cardiac cachexia develops; preferably first 2 weeks of life.
Surgical Management
Median sternotomy with cardiopulmonary bypass.
Removal of pulmonary trunk with aortic patch at pulmonary trunk removal sites.
Placement of RV to branch PA conduit to form a pulmonary artery.
Closure of VSD.
Truncal valve repair if necessary.
Postoperative Considerations
Pulmonary hypertensive crisis.
Low cardiac output.
Cyanosis.
Dysrhythmias.
Neoaortic (truncal) valve stenosis/regurgitation.
Residual VSD.
Postoperative Checklist
Pulmonary hypertension:
Evaluate for residual VSD and RVOT obstruction.
Treat pulmonary hypertension.
RV dysfunction:
Institute appropriate pharmacologic and volume support for the RV.
Allow desaturation secondary to shunting at the atrial level.
Monitor for and treat dysrhythmias, especially JET.
Coarctation of the Aorta (COA)
Background/Definition
Constriction of the thoracic aorta distal to the left subclavian artery (Figure 5.16).
Pathophysiology/Clinical Presentation
Neonates:
Present in first week of life if blood flow dependent on PDA—ductal closure leads to LV pressure overload and failure with resultant pulmonary edema and circulatory collapse.
FIGURE 5.16 • Coarctation of the Aorta.
Presents in shock; tachypnea, tachycardia, decreased or absent lower peripheral pulses, hypotension, hepatomegaly.
Older children:
Present with hypertension on a routine physical examination.
Have either hypertension and/or decreased femoral pulses.
Diagnosis can be delayed secondary to hypertension evaluation.
Often have complaints of headache, leg and stomach cramping, cool extremities, and decreased lower extremities (LE) pulses.
Diagnostic Evaluation
Chest radiograph: cardiomegaly and signs of CHF
Electrocardiograph—LV strain pattern
Echocardiogram—diagnostic in most cases.
Demonstrates the anatomic coarctation.
Lack of flow in the descending aorta.
Coarctation.
Size of the transverse arch.
Any other cardiac anomalies.
Cardiac catheterization: can be performed in a stable infant maintained on prostaglandins (PGE) for further delineation of cardiac anatomy.
CT scan or MRI can be used for the child with a difficult arch to image with echocardiogram.
Management
Surgical approach.
Left thoracotomy for most cases.
Resection with (extended) end-to-end anastomosis.
Narrowed coarctation section is excised, and direct anastomosis is done with the two segments.
Prosthetic interposition graft.
Used in patients >10 years of age, or with an associated aneurysm or long segment coarctation.
Coarctation is excised and interposition graft placed to connect segments of the transverse and descending aorta.
Mediansternotomy is necessary for patients with associated intracardiac anomalies.
Postoperative Considerations
Paradoxical hypertension.
Early (first 48 hours) related to release of the stretch on baroreceptors in the carotid arteries and aortic arch after removal of the coarctation.
48 to 72 hours is related to elevated levels of renin and angiotensin.
Spinal cord ischemia; paraplegia, rare but serious.
Residual coarctation—defined as postoperative arm leg BP discrepancy— requires balloon dilation or reoperation.
Recurrent laryngeal nerve injury.
Postoperative Checklist
Treat hypertension aggressively.
Evaluate for residual arch obstruction.
Check four extremity BP and neurological function.
Aortic Stenosis (AS)—Valvar
Background/Definition
Malformation of the aortic valve that causes obstruction to ejection of blood from the left ventricle LV.
Infants who present with AS represent a spectrum of anatomic variants from HLHS to thickened aortic valve.
Older children who present with AS typically have little sequelae.
Can occur at the valvular level, supravalvar or subvalvar region.
Pathophysiology
Neonates:
Pressure overload of LV with LVH (elevated LV end diastolic pressure [LVEDP]) and eventually pulmonary edema.
With critical AS, PDA provides increased cardiac output via R→L shunt.
Older children:
Chronic obstruction leads to LV overload and LVH.
With severe hypertrophy, subendocardial tissue ischemia may be noted.
Ischemia is further exaggerated by stress/exercise.
Clinical Presentation
Timing of presentation is related to severity of obstruction.
Neonates: shock and signs of circulatory arrest.
Infants: Signs of CHF.
Older children: systolic murmur radiating to neck and apex; ejection click suggests valvar stenosis rather than supra- or subvalvar narrowing, narrow pulse pressure with normal BP.
Diagnostic Evaluation
Chest radiograph.
Neonates: cardiomegaly with pulmonary edema.
Electrocardiograph.
Older children: LVH with possible ST segment changes.
Echocardiogram.
Sufficient for diagnosis.
Must evaluate left-sided cardiac structures.
Cardiac catheterization.
Only indicated with balloon valvuloplasty
Management
Timing.
Neonates.
Require immediate intervention.
Catheter balloon valvuloplasty or surgical valvotomy is often initial treatment of choice.
Older infants and children.
Require intervention when symptomatic or with high left ventricular LV outflow tract (LVOT) pressure gradient (e.g., LVOT gradient >50 mmHg, anginal pain, or ST segment changes during exercise).
Surgical procedure.
Dependent on anatomy of the valve and other cardiac structures as well as the age of the patient.
Stage 1 Norwood.
Surgical valvotomy.
Older children.
Aortic valve replacement.
Ross procedure: procedure of replacing the aortic valve with the patient’s own pulmonary valve and then using a pulmonary allograft to replace the pulmonary valve; this includes translocation of coronary arteries.
Konno procedure: aortic valve replacement with enlargement of LV outflow tract; this includes translocation of coronary arteries.
Ross-Konno procedure: uses pulmonary autograft in aortic position and enlargement of the LV outflow tract in addition to placement of pulmonary homograft; this includes translocation of coronary arteries.
Postoperative Considerations
Ross procedure will require replacement of pulmonary allograft.
Left ventricular outflow tract (LVOT) stenosis.
Mitral regurgitation.
Left bundle branch block (LBBB) or heart block.
With Ross/Konno or supravalvar repair at risk of coronary ischemia.
Preoperative Management—Single Ventricle Physiology
Balance pulmonary and systemic circulations.
Goal is to provide enough pulmonary circulation to provide adequate O2 delivery and prevent acidosis.
Achieved by maintaining an arterial O2 saturation of 75% to 80% (Qp:Qs = 1:1).
Unbalanced circulation results in inadequate pulmonary blood flow, hypoxemia/cyanosis.
Excessive pulmonary blood flow results in CHF.
Single ventricle: Goal Qp:Qs = 1:1.
Excessive pulmonary blood flow: Qp:Qs = 2:1.
High saturations >80%.
CHF.
Inadequate pulmonary blood flow: Qp:Qs = 0.7:1.
When Qp:Qs is low, SaO2 drops <70%.
Management:
Decrease PVR (increase pH by hyperventilation and sodium bicarbonate infusion, increase FiO2, lower mean airway pressure).
Raise systemic vascular resistance (calcium gluconate, maintaining or starting inotropic vasopressors).
Prostaglandin (PGE) infusion in ductal-dependent lesions with restrictive PDAs.
Excessive pulmonary blood flow (SaO2 >90%).
Results in reduction of systemic blood flow.
Despite higher oxygen saturation, tissue perfusion is compromised.
Treatment includes:
Maneuvers to increase PVR and decrease SVR.
Alveolar hypoxia (FiO20.21 or lower with nitrogen).
Permissive hypercarbia (pH 7.30-7.40 with PaCO2 45-50 mmHg).
Afterload reduction (e.g., milrinone, nipride).
Minimize inotropic agents (particularly those with alpha effects).
In this setting, patients usually require urgent surgical intervention.
Intraoperative Approach Considerations in Children with CHD
Palliative versus curative.
Thoracotomy versus median sternotomy:
With or without cardiopulmonary bypass.
Deep hypothermic circulatory arrest.
Low-flow cerebral perfusion.
Thoracotomy:
Used for procedures including PDA ligation, BT shunt placement, coarctation repair, and PA banding.
Entails collapse of one lung during the operation.
Postoperative problems specific to this approach include thoracic duct damage, phrenic nerve injury, recurrent laryngeal nerve injury.
Cardiopulmonary bypass: A mechanical means of circulating and oxygenating blood volume while diverting most of the circulation away from the cardiopulmonary system.
Basic components include: pump, oxygenator, reservoir, tubing, and cannulas to carry blood between patient and oxygenator.
Most intracardiac repairs also require cardioplegia to arrest the heart.
This is achieved by cross-clamping the aorta between the arterial cannulation site and the aortic root where the coronary arteries arise.
Cardioplegia cools and protects the myocardium.
Cardiopulmonary bypass sequelae.
Neurologic: emboli (air and/or debris), low cerebral blood flow.
Cardiac: ischemia, emboli, direct coronary artery injury.
Pulmonary: complement-induced endothelial damage.
Renal: elevated antidiuretic hormone (ADH) levels, additional injury due to red blood cell (RBC) hemolysis.
Gastrointestinal: emboli.
Coagulation: complement activation, platelet consumption, altered platelet aggregation, coagulation factor dilution.
Endocrine: elevated growth hormone, elevated insulin, hyperglycemia.
Cardiopulmonary bypass (CPB) effects on ICU course.
Rewarming: may require volume infusions to maintain cardiac output.
Bleeding: due to heparinization during CPB, platelet dysfunction, dilution of coagulation factors.
Fluid overload: most centers now hemofiltrate at end of CPB to minimize effects of fluid overload.
Postperfusion syndrome: characterized by a whole-body inflammatory reaction; increased capillary permeability, leukocytosis, fever, peripheral vasoconstriction, hemolysis, bleeding diathesis.
Deep hypothermic circulatory arrest: facilitates repair of complex lesions, allows for a totally bloodless field and removal of venous cannulae that may obscure visualization of intracardiac structures.
Technique: cooling to less than 20°C, removal of bypass cannulas.
Deep hypothermia and circulatory arrest (DHCA) sequelae: seizures, choreoathetosis.
General Postoperative Management Considerations
Precise anatomic diagnosis including pathophysiologic effects of defect on cardiovascular system and other organ systems.
Patient’s noncardiac medical and surgical history and preoperative medications.
Details of the operation.
Anesthetic agents used in operating room (OR).
Intraoperative complications.
Congestive Heart Failure
Robin McKinney
Definition
Chronic inability of the heart to generate enough cardiac output to effectively meet the body’s metabolic demands.
Signs and symptoms include edema, respiratory distress, growth failure, hepatomegaly, and exercise intolerance.
Etiology
Congenital heart lesions or cardiomyopathy.
Inflammation from infections, genetic factors, toxins, or chemotherapy.
Pathophysiology
Structural defects or acute damage to the heart leads to decreased ability of cardiac muscle to pump blood adequately.
Pressure or volume overload leads to decreased cardiac contractility, decreased output, and failure to adequately supply systemic demand.
Preload: The volume needed to fill the heart. As preload increases, cardiac output increases until the preload exceeds the optimum range. When preload exceeds the optimum range, the cardiac output no longer increases, and the body begins to become fluid overloaded.
Afterload: The force against which the heart must pump. Can be increased by fixed obstruction (e.g., AS) or by increasing peripheral vascular resistance.
Too much preload or afterload from any cause will contribute to the signs and symptoms of heart failure (see Figure 5.1).
As cardiac function decreases, neurohormonal mechanisms are activated, resulting in compensation; however, they are associated with deleterious effects.
Activation of the renin-angiotensin-aldosterone system results in sodium and water retention aimed at increasing circulatory volume and maximizing preload.
Sympathetic nervous system activation leads to catecholamine (e.g., norepinephrine) release. Cardiac output is then increased by increased cardiac contractility and vasoconstriction of blood vessels, resulting in improved preload.
Long-term sequelae of these compensatory mechanisms lead to volume overload and increased cardiac workload.
Volume overload contributes to myocardial hypertrophy, which is initially beneficial, but eventually can be a risk for myocardial ischemia, which then leads to decreased contractility.
Overstretching of cardiac muscle leads to worsening contractility.
Pulmonary edema results from fluid overload.
Cardiac remodeling is caused by a catecholamine response and changes in pressure-volume relationship, resulting in myocardium that does not function as well.
Cycle is progressive with deterioration accelerating over time as initial compensatory mechanisms lead to progressive damage.
Clinical Presentation
Infants: tachypnea, feeding difficulties (e.g., decreased volume or increased time spent feeding), poor weight gain, excessive perspiration (especially when feeding), and excessive irritability. Wheezing and tachypnea from pulmonary congestion often mistaken for bronchiolitis.
Children: fatigue, exercise intolerance, anorexia, abdominal pain, dyspnea, and cough.
Infants and children:
Tachycardia, decreased peripheral pulses, delayed capillary refill, and cool extremities.
Abdominal pain is a common presenting complaint and may be overlooked or dismissed. Hepatomegaly, ascites can be present with abdominal distension.
Edema may be present in dependent portions of the body (e.g., lower extremities in an ambulatory child; body wall and sacrum if nonambulatory).
Diagnostic Evaluation
Chest radiograph: enlarged cardiac silhouette/cardiomegaly.
Exaggerated pulmonary arterial vessels may be present in left-to-right shunts.
Pulmonary edema manifests as fluffy perihilar infiltrates.
Atelectasis may be present as a result of compression of one of the bronchi or lung lobes by the enlarged heart. This can be mistaken for a retro-cardiac opacity/consolidation, leading to a misdiagnosis of pneumonia.
Pleural effusions may be present; usually bilateral.
Abdominal radiograph: if obtained for complaints of stomach pain, may demonstrate incidental finding of cardiomegaly.
Electrocardiogram: may indicate LVH, RVH, or an underlying rhythm abnormality responsible for the heart failure.
Echocardiogram: most useful in evaluating the cardiac structure and function.
Metabolic acidosis may be present with a large base excess and an elevated lactate.
Serum B-type natriuretic peptide (BNP) is elevated in response to ventricular wall tension or stretch; useful in trending the response to therapy in heart failure.
Depending on the degree of dysfunction, other laboratory values may be abnormal:
Hyponatremia due to volume overload, elevated creatinine due to underperfusion of the kidneys, elevated transaminases (AST/ALT).
Management
The initial goal in management of CHF is resuscitation and stabilization.
In an acute exacerbation or in fulminant failure, it is important to note that many of the outpatient medications can counteract therapies used in the acute setting.
Therapy should be tailored to the presenting problem and underlying lesion with the goal of maximizing cardiac output.
Optimize volume status, judiciously.
Augment cardiac contractility.
If adequate perfusion in the presence of volume overload, diuretics indicated. Furosemide and chlorothiazide are first-line agents.
Patients with poor perfusion and volume overload require additional support.
Afterload reduction: reduces the force the heart is pumping against. This is the most important concept.
Vasodilators (e.g., nitroprusside) and diuretics can help with poor perfusion and congestion, but must be used cautiously in the setting of hypotension.
Inotropic support with β-agonists such as dopamine or dobutamine can improve cardiac output.
Phosphodiesterase inhibitors (e.g., milrinone) are both an inotropic agent and a vasodilator.
If inotropic support is needed, discontinue chronic beta-blocker therapy.
If poor perfusion not associated with fluid overload, fluid resuscitation and inotropic support may be needed.
In addition to the β-agonists, epinephrine may be helpful. At low doses, it provides inotropic support and vasodilation, and at higher doses, inotropic support and vasoconstriction.
Vasopressin causes peripheral constriction, and while not considered an inotrope, it may improve cardiac output.
Calcium increases myocardial contractility; maintain normal ionized calcium levels in the setting of heart failure.
A variety of medications are used in the outpatient setting for long-term management.
Diuretics such as furosemide and chlorothiazide help manage volume overload.
Aldactone is a potassium-sparing diuretic that has the added benefit of preventing cardiac remodeling.
β-blockers counteract the long-term effects of sympathetic nervous system activation.
Angiotensin-converting enzyme inhibitors provide afterload reduction, improving cardiac output.
Digoxin is used to help improve cardiac contractility.
Endocarditis
Caroline Bauer
Definition
Infection of the endothelial surface of the heart.
Can develop on any structure of the heart.
Etiology
Risk factors:
Prosthetic valves.
Previous history of endocarditis infection.
Complex cyanotic CHD.
Surgically placed systemic-to-pulmonary artery shunts.
Injection drug use.
Indwelling central venous catheters.
90% of cases occur in children with heart disease, most commonly in CHD.
Incidence is 0.3 per 100,000 children with an overall mortality rate of 11.6%.
Most common causative pathogens:
Least virulent: α-hemolytic streptococci, enterococci, and coagulase-negative staphylococci.
Most virulent: Staphylococcus aureus (accounts for 57% of all cases of endocarditis), Streptococcus pneumoniae, β-hemolytic streptococcus, and fungal sources such as Candida and Aspergillus.
Pathophysiology
Begins with damage to the endocardial cells of the heart.
Leads to thrombus formation.
Pathogens circulating in the bloodstream adhere to the thrombus, and continued deposition of fibrin and platelets occurs, providing a protected environment for organisms to grow and flourish.
Clinical Presentation
Fever is the most common presenting symptom.
Fulminate endocarditis:
High fever.
Hemodynamic instability.
Subacute presentation:
Arthralgias.
Myalgias.
Headache.
Malaise.
Relapsing fever.
Poor appetite.
Almost all patients with endocarditis will have a murmur on physical examination.
Other less common physical examination findings include petechiae, Osler nodes, Janeway lesions, Roth spots, and splinter hemorrhages (see Figures 5.17 and 5.18).
Diagnostic Evaluation
The modified Duke criteria are the standard approach used to diagnose endocarditis (Table 5.2).
Criteria for definitive diagnosis of endocarditis:
Pathologic evidence of intracardiac or embolized vegetation or intracardiac abscess, OR
Two major criteria findings, OR
One major and three minor criteria findings, OR
Five minor criteria findings.
For the possible diagnosis of endocarditis, the following criteria must be met:
One major and one minor criteria findings, OR
Three minor criteria findings
Laboratory evaluation.
Blood cultures.
Three peripheral blood cultures from different locations within a 24-hour period; first culture should be obtained prior to antibiotics.
Complete blood count (CBC); may reveal anemia; leukocytosis is uncommon.
Urinalysis (UA): may reveal micro- or macrohematuria, suggesting renal embolization of vegetation.
Diagnostic studies.
Echocardiogram.
Management
Extended-course intravenous (IV) antimicrobials (typically 4-6 weeks) under infectious disease guidance is the mainstay of therapy.
FIGURE 15.17 • Osler Nodes. A patient with Osler nodes from Streptococcus viridans bacterial endocarditis.
FIGURE 15.18 • Janeway Lesions. A Janeway lesion on the sole of an adolescent female with enterococcal endocarditis
Empiric therapy should be directed at the most common pathogens—streptococci and staphylococcus—until susceptibilities are available, and then targeted antimicrobial therapy is determined.
Standard initial antibiotic therapy is penicillin or ampicillin plus vancomycin.
Surgical referral indications include persistent infection, significant embolic events, new heart block, an abscess that is large or increasing in size, or progressive CHF.
Hypertension
Tresa E. Zielinski
Definition
Stages:
Prehypertension: 120-139/80-89 mmHg.
Stage 1: 140-159/90-99 mmHg.
Stage 2: 160+/100+ mmHg.
TABLE 5.2 Duke Criteria
Major Criteria
Positive blood culture.
Positive echocardiogram on two occasions.
New valvular regurgitation.
Minor Criteria
Predisposing heart condition including previous infective endocarditis.
Janeway lesions (painless hemorrhagic lesions on palms and soles).
Injection drug use.
Glomerulonephritis.
Fever.
Osler nodes (painful lesions at fingertips).
Major arterial emboli.
Roth spots (retinal hemorrhages).
Septic pulmonary infarcts.
Positive rheumatoid factor.
Mycotic aneurysm.
Single positive blood culture.
Intracranial hemorrhage. Conjunctival hemorrhage.
Serologic evidence of active infection with an “organism consistent with endocarditis.”
Table created by Bauer, C. (content contributor).
National High Blood Pressure Education Program (NHBPEP) Working Group on High Blood Pressure in Children and Adolescents.
Average systolic BP and/or diastolic BP that is ≥95th percentile for gender, age, and height on ≥3 occasions is hypertension.
Hypertension is classified as prehypertensive, stage 1 or stage 2 (see above). All children and adults with a BP above 120/80 mmHg should be classified as prehypertensive.
Key differences between stage 1 and stage 2; confirmed stage 1 allows for time for evaluation prior to intervention, while stage 2 requires swift evaluation (referred for evaluation within one week or sooner if symptomatic) and intervention. In symptomatic stage 2 hypertension, immediate intervention is required and prompt referral with a specialist.
Stage 1 hypertension is reevaluated on repeat visits; three separate measurements within 1 month.
Secondary hypertension is more common in children than in adults. This is hypertension that is not primary in nature, but related to other etiologies (e.g., kidney disease).
Stage 2 hypertension in children should be investigated more thoroughly than other stages.
Etiology
Essential hypertension.
Unknown etiology: diagnosis of exclusion.
Genetic: strong familial association.
Secondary hypertension:
More common in children than adults.
60% to 70% of hypertension in children is secondary to kidney disease. Other causes include: Adrenal gland, medications, obstructive sleep apnea, stress, anxiety, coarctation of the aorta, endocrine causes, pregnancy, metabolic syndrome.
Presentation
History:
Family history (e.g., cardiovascular disease, deafness, endocrine disorders, kidney disease, obstructive sleep apnea).
Patient history (e.g., umbilical artery/vein catheterization, CP, diaphoresis, dyspnea on exertion, edema, growth failure, heat/cold intolerance, palpitations, headaches, joint pain/swelling, myalgias, hematuria, recurrent rashes, snoring/sleep disturbances, urinary tract infections (recurrent), weight/appetite changes).
Physical examination:
All children >3 years of age should have BP checked on every health care visit.
All children <3 years of age with history of CHD, prematurity, kidney disease, urinary tract infections, malignancy, elevated intracranial pressure, or proteinuria should have BP checked with every health care visit.
Physical examination clues to hypertension.
Tonsillar hypertrophy (sleep-disordered breathing).
Papilledema (intracranial hypertension).
Acanthosis nigricans (type 2 diabetes).
Murmur (coarctation of aorta).
Abdominal mass (kidney tumor, hydronephrosis, polycystic kidney disease).
Disparate pulses; upper pulses > lower (coarctation of aorta).
Elfin or Moon facies (Williams syndrome, Cushing syndrome).
Thyroid enlargement (hyperthyroidism).
Muscle weakness (Hyperaldosteronism).
Diminished pain response (Familial dysautonomia).
Ambiguous genitalia (Adrenal hyperplasia).
Advanced puberty (intracranial tumor/pathology).
Most patients are asymptomatic on presentation and may not have a history suggestive of hypertension.
Plan
Diagnostic studies.
Laboratory evaluation.
Should be obtained in anyone with stage 1 hypertension or higher.
CBC: Anemia is a classic sign of chronic kidney disease.
Renal function panel: Evaluation of kidney function (i.e., BUN/creatinine) and electrolytes. Hyperphosphotemia and hypocalcemia are commonly noted in kidney disease.
Urinalysis.
Urine protein/creatinine ratio; consider.
Lipid panel.
Fasting lipid panel and fasting blood glucose measurement; obese patients.
Echocardiogram: evaluation for LV hypertrophy (LVH).
Renal ultrasound: evaluation for kidney scarring, congenital abnormalities, unequal kidney size.
Retinal examination: Evaluation for retinal vascular changes.
Nonpharmacologic therapy.
First-line plan in stage 1 hypertension.
Lifestyle changes:
Weight loss; exercise, dietary modifications.
Reduce salt intake: 2.4 g sodium restriction/day.
Increase fresh fruit and vegetables.
Increase low-fat dairy products.
Family-based:
Avoidance of smoking and alcohol intake.
Pharmacologic therapy:
First-line in stage 2 hypertension.
General guidelines and classification.
ACE (angiotensin-converting enzyme) inhibitors (“-prils”): Dilate blood vessels to decrease resistance.
Side effects:
Cough.
Skin rash (red, itchy).
Dizziness/lightheadedness, orthostatic hypotension.
Taste impairment (salty or metallic).
Edema (lower extremities).
Hyperkalemia.
Decrease in glomerular filtration rate (GFR).
Precautions:
Not to be used in volume-depleted patients.
Not to be used in patients with bilateral renovascular hypertension.
Avoid salt substitutions as they contain potassium.
Avoid nonsteroidal anti-inflammatory (NSAID) medications.
Check BP and kidney function regularly.
ARB (angiotensin II receptor blockers) (“-sartan”): angiotensin II receptor blockers decrease chemicals that cause vasoconstriction; decrease intraglomerular pressure through decreasing efferent arteriolar tone.
Useful in patients with diabetes, preferred class of medication if ACE inhibitors are not well tolerated because of renoprotective (reduces microalbuminuria) properties.
Side effects:
Dizziness, orthostatic hypotension (worse with first dose, need to take for a week+ before full effect), muscle cramping, diarrhea.
Precautions:
Monitor BP and kidney function.
Calcium channel blockers (“-pine”): dilate blood vessels, decreasing cardiovascular resistance. These agents slow the movement of calcium into cells of the heart and blood vessels. May be the desired class in patients with asthma.
Side effects: edema, arrhythmias, fatigue, dizziness.
Precautions: monitor heart rate, avoid grapefruit, avoid alcohol, contraindicated in patients with sick sinus syndrome.
Diuretics: decrease blood volume and excrete sodium.
Thiazide-like: most effective in lowering BP (metolazone, hydrochlorothiazide).
Can be used as primary therapy.
Can enhance the effects of other antihypertensive agents.
Requires salt restriction as concurrent therapy.
Can infrequently cause hypokalemia, glucose intolerance, adverse lipid effects.
Periodic blood chemistries needed.
Loop: more powerful; can be helpful in hypertensive emergenices (e.g., furosemide, bumetanide, torsemide).
Potassium sparing: can be helpful with CHF; usually prescribed in conjunction with one of the other two types (spironolactone).
Side effects: frequent urination, electrolyte imbalance, fatigue or weakness, muscle cramping, dizziness, dehydration, anorexia.
Vasodilators (e.g., hydralazine, minoxidil).
Reserved for patients failing other therapies.
Unfavorable side-effect profile.
Peripheral α1-antagonists and centrally acting α2-agonists.
May be associated with orthostatic hypotension.
α/β-Blockers (“-lol”): β-blockers block the effects of sympathetic nervous system (adrenaline) in the heart.
Reduction in heart rate results in a reduction of cardiac output.
Use with caution in ambulatory patients.
Side effects: β-blockers are contraindicated in children with heart block, asthma, or pregnancy. May reduce the ability of a diabetic patient to identify a hypoglycemic event; use with extreme caution in diabetic patients.
Hypertensive crisis management:
Intravenous (IV) form of antihypertensive medications (e.g., esmolol, labetolol, nicardipine, hydralazine).
Fluid management and restriction.
Goal is NOT to decrease BP to a normal level, but rather to return BP to a safe level.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
