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The history of cardiac surgery is replete with innovation, setbacks, successes, and surprises. Before the late 19^th century, direct treatment of the heart was considered unethical and unprofessional due to the known risks of ventricular fibrillation associated with direct manipulation of the organ and suture repair of the heart, along with the creation of a pneumothorax upon entry to the pleural cavity. In 1896, Ludwig Rehn demonstrated that these impediments to repair could be overcome when he successfully performed the first known suture repair of a myocardial battle injury.1

The introduction of positive-pressure endotracheal anesthesia enabled clinicians to minimize the dangers of a pneumothorax and allow access the heart through the pleural cavities without causing the lungs to collapse. The introduction of extracorporeal circulation (i.e., cardiopulmonary bypass) by John Gibbon in 1953 enabled surgeons to isolate the heart and lungs from the circulation without producing irreversible tissue anoxia.¹ The development of electric defibrillation and induced pharmacologic cardiac arrest made stopping and restarting the heart possible with consistent predictability; these innovative myocardial protection techniques protected and conserved myocardial energy resources during the period of induced cardiac arrest. Improved diagnostic imaging and monitoring capabilities have allowed clinicians to visualize the heart, identify specific pathoanatomic changes, record the heart’s electric activity, measure blood pressure and flow, and assess ventricular function. These imaging and monitoring improvements, along with the refinement of mechanical and bioprosthetic materials, improved anesthetic agents, percutaneous and newer minimally invasive surgical techniques, and additional technologic advances, have made development of more effective procedures and devices possible to revascularize the myocardium, repair and replace valves, treat aneurysms, alter conduction disturbances, and assist and replace a failing heart.¹ More recently, the COVID-19 pandemic has tested the ability of patients, clinicians, and health care institutions to treat patients with cardiac conditions, to educate individuals and groups, and to communicate with others in meaningful and effective ways. Nurses and their clinical colleagues have met these challenges with knowledge, skill, experience, and compassion. Related information is available in Chapters 11, 34, and 36.

Definitions

Allograft (Homograft) Tissue from another human, commonly procured from a cadaver. Often refers to the aortic valve alone or with a portion of the attached aorta. Allografts are processed in a sterile manner and cryopreserved. When needed for surgery to replace the aortic valve or a portion of the ascending aorta and valve, the appropriately sized allograft is thawed and implanted.

Annuloplasty The surgical repair of a dilated valve annulus, most commonly with a cloth-covered prosthetic annuloplasty ring sewn to the valve (usually mitral or tricuspid) annulus, thereby reducing the circumference of the annulus and enabling the leaflets to coapt and make the valve competent.

Aortic Aneurysm A localized or diffuse dilation of the arterial wall. Weakening and degeneration of the medial layer of the aortic wall leads to progressive enlargement of all layers of the aorta. Thoracic aortic aneurysms can occur in the ascending aorta, the aortic arch, or the descending aorta and extend into the abdominal aorta and branch vessels.

Aortic Dissection A unique condition that affects the aortic media in which repeated stress (often from hypertension) and a congenital predisposition to injury produce a tear in the intimal layer. Blood enters the tear, creating a dissecting hematoma within the tunica media and forming a false lumen. As the false lumen enlarges, with more blood entering the tear, the true lumen compresses, risking occlusion of the branches of the aorta. The intimal tear usually forms in the ascending aorta, although it can originate in any portion of the thoracic aorta. Surgery (excision of the aorta that contains the tear and replacement with a prosthetic graft) is usually indicated for ascending aortic and transverse aortic arch dissections, and for impending rupture in other sections (e.g., descending portion) of the aorta.

Aortic Insufficiency (AI) Also called aortic regurgitation; a condition that occurs when the aortic valve leaflets do not close properly (or have tears) and the valve becomes incompetent (i.e., leaks), thereby allowing regurgitation of blood from the aorta back into the left ventricle during diastole.

Aortic Stenosis (AS) The development of stiff and fibrotic valve leaflets or a narrowing of the orifice of the aortic valve itself that leaves only a small opening through which blood can be ejected. A calculated aortic valve orifice of less than 1 cm² is considered critical AS.

Atrial Septal Defect (ASD) An opening in the atrial septum, ASDs are among the frequently seen congenital anomalies in adulthood. Depending on the size of the defect (commonly the size of a quarter), there is a shunting of blood from the left atrium to the right atrium and subsequent increased pulmonary blood flow.

Balloon Valvotomy or Valvuloplasty A catheter-based interventional procedure to enlarge a (stenotic) valve opening. Balloon valvotomy for the mitral valve is performed with a catheter percutaneously inserted into a large vein and threaded to the right atrium, where a septal puncture is made to allow access to the mitral valve. In aortic valvuloplasty, the catheter is inserted into the femoral artery and threaded to the aortic valve, where the balloon tip is positioned across the aortic valve and the balloon is inflated to dilate the aortic valve orifice.

Cardioplegia Literally, “paralysis of the heart”; pharmacologically induced cardiac arrest during surgery on the heart. Potassium is the most commonly used arresting agent, but the solutions may also contain electrolytes, buffers to maintain appropriate pH, glucose, metabolic substrates, calcium antagonists, tromethamine, heparin, and antiarrhythmic agents; the carrying solution may be crystalloid or blood (favored for its oxygen-carrying capacity). The purposes of cardioplegia are protection of the myocardium against irreversible ischemic injury during the aortic cross-clamp period when the heart is arrested and conservation of energy resources that can be used after removal of the cross clamp.

Cardiopulmonary Bypass (CPB) A temporary mechanical substitution for the heart and lungs using a device that drains systemic venous return (thereby decompressing the heart) into an oxygenator that removes excess carbon dioxide and adds oxygen (simulating the lungs) and pumps arterialized blood into the systemic circulation (simulating the heart). Employing CPB enables surgeons to isolate the heart by cross-clamping the aorta and to pharmacologically induce cardiac arrest to create a dry, quiet operative field in which to perform the surgical repairs. During the period of cardiac arrest, the rest of the body can be adequately perfused via CPB.

Coarctation of the Aorta A congenital narrowing of the thoracic aorta, usually in the area of the ligamentum arteriosum (formerly the fetal patent ductus arteriosus, which shunts blood from the pulmonary artery to the aorta).

Commissurotomy The opening or separation of fused valve leaflet commissures (in the adult, generally the mitral or pulmonary valve).

Congenital Heart Disease Cardiac anomalies present at birth and requiring repair at birth or later in life. In this section, some of the congenital anomalies more likely to be seen in adulthood are discussed.

Dysrhythmia Surgery for Atrial Fibrillation (AF) Surgery designed to block or redirect aberrant atrial fibrillatory impulses toward the atrioventricular node to achieve normal sinus rhythm. See also Maze Procedure.

Extracorporeal Membrane Oxygenation (ECMO) ECMO often has been employed for acute respiratory distress syndrome; more recently it has been used for COVID-19 patients who may have both acute respiratory and cardiac failure. Either a vein-to-vein (mainly respiratory problems) or a vein-to-artery (both respiratory and cardiac problems) circuit is established and connected to an oxygenator, a heat exchanger (to control blood temperature), and a pump to propel the blood. Patients are anticoagulated while they are on ECMO to prevent clotting or microemboli.

Hybrid Suite Procedure or operating room that integrates interventional and traditional surgical equipment and supplies and imaging and monitoring devices.

Hypothermia Cooling of the patient during cardiac surgery. Hypothermia can be induced (elective) or inadvertent. Induced systemic hypothermia is achieved with a heat exchanger incorporated into the cardiopulmonary bypass circuit; induced cardiac hypothermia is achieved with infusion of cooled cardioplegia solution into the coronary circulation. Topical cardiac cooling is achieved by pouring cold solutions or ice slush onto the heart.

Implantable Cardioverter-Defibrillator (ICD) A device that provides a shock to the heart for tachycardia above a predetermined rate or for ventricular fibrillation; ICDs also have the capability to provide bradycardia therapy. The device is usually inserted transvenously in the electrophysiology or cardiac catheterization laboratory. Patients with ICDs who undergo surgery have a magnet placed over the generator (usually in the right or left upper chest) to turn off the device and avoid frequent shocks during induced cardiac arrest. After surgery, the magnet is removed and the ICD is again activated.

Left Atrial Appendage Closure (LAAC) In patients with AF (unrelated to valve disease), the LAA is a primary source of thrombus formation leading to stroke. Treatment often involves the use of oral anticoagulants (e.g., warfarin). In some patients, anticoagulation therapy is contraindicated because of an increased risk for major bleeding due to, for example, hemorrhagic tendencies or hypersensitivity to anticoagulant drugs. Occlusion of the LAA with a device (e.g., WATCHMAN), or surgical closure (oversewing the appendage) or surgical exclusion (e.g., excising the appendage) may be employed to reduce thromboembolic risk.

Maze Procedure Surgery performed to correct AF and return the heart to normal sinus rhythm. The procedure creates precisely placed lesions (e.g., with cryoenergy, radiofrequency) where re-entrant circuits along conduction pathways produce AF. The irregular fibrillatory impulses are unable to cross these lesions and thus are redirected down the normal conduction pathway—from sinoatrial node to atrioventricular node.

Minimally Invasive Cardiac Surgery Operations that use smaller incisions, percutaneous and/or endoscopic access, endovascular techniques, or off-pump (i.e., no cardiopulmonary bypass) procedures. A common procedure in minimally invasive surgery is the endoscopic video-assisted excision of saphenous vein coronary bypass grafts. In other cases, smaller sternal or thoracic chest incisions or ports may be used for target areas of the heart that can be accessed through these minimal incisions (e.g., surgery for coronary bypass operations for single-vessel disease, AF procedures, and some valve procedures).

Mitral Regurgitation (MR) A condition that occurs when one or more components of the mitral valve apparatus prevent competent closure of the valve with subsequent regurgitation of blood into the left atrium.

Mitral Stenosis (MS) A narrowing of the mitral valve orifice that creates an impedance to flow across the valve.

Myocardial Protection Techniques Techniques or procedures designed to conserve myocardial energy resources and limit the amount of ischemic tissue injury that can occur. The use of cardioplegia and induced hypothermia (see previous definitions) to arrest and preserve the heart form the foundation of myocardial protection. Another myocardial protective measure includes insufflation of CO₂ gas through a catheter placed into the pericardial well. The CO₂ gas displaces ambient air (which can pose a risk for air bubbles trapped within the heart) but also dissolves approximately 25 times faster in the blood than room air and is less harmful to cardiac tissue.

Myocardial Revascularization Also referred to as coronary artery bypass grafting. Surgical procedure performed to increase blood flow to those portion(s) of the heart with impaired perfusion due to atherosclerotic coronary artery disease (CAD). Conduits (i.e., bypass grafts) of the patient’s own tissue (autograft)—most commonly the internal mammary artery or other arteries (e.g., radial artery) and the greater saphenous vein—are attached directly to the affected coronary artery at a site distal to the narrowed atherosclerotic lesion. The procedure does not cure CAD; its goal is to improve coronary perfusion.

Patent Ductus Arteriosus (PDA) A duct between the pulmonary artery and the aorta present in the fetus. The duct usually closes within 1 or 2 weeks after birth and becomes the ligamentum arteriosum.

Percutaneous Coronary Intervention (PCI) A catheter-based interventional technique performed with fluoroscopy in the cardiac catheterization laboratory, usually performed for acute or chronically obstructed coronary arteries. A percutaneously inserted catheter is threaded to the right or left coronary ostia where the balloon within the catheter is positioned across the coronary artery at the site of the narrowing. The balloon is inflated, enlarging the coronary lumen. A stent (bare metal or coated) is then inserted to maintain coronary artery patency. Stent insertion is the most common form of PCI.

Pericardiectomy, Pericardial Window Pericardiectomy is the partial excision of an adhered thickened fibrotic pericardium to relieve constriction of the heart and great blood vessels. In patients with chronic cardiac effusions, the creation of a pericardial window (excision of a portion of the pericardial or pleural wall) between the pericardial sac and the pleural space drains the fluid. In patients with chronic effusions, the window to the pleural space generally allows future fluid accumulation to be reabsorbed.

Pulmonary Stenosis Fusion of the pulmonary valve cusps at the commissures or fibromuscular obstruction proximal to the valve can create an obstruction to the right-ventricular outflow tract.

Transcatheter Aortic Valve Replacement (TAVR) A minimally invasive heart procedure to replace a narrowed aortic valve. A catheter is commonly inserted into the femoral artery and, under fluoroscopy, threaded to the aortic valve, where the aortic valve prosthesis is deployed into the narrowed portion of the aortic valve annulus.

Transplantation Replacement of the patient’s heart with a human donor heart, or replacement of one or both lungs with lungs from one or two donors, or one lung from a living donor. Heart donors are persons with irreversible brain injury who do not have atherosclerotic heart disease; age limitations have become less restrictive, and donors and recipients may be 60 years or older in certain cases. Severe pulmonary disease is a contraindication for lung donation.

Tricuspid Regurgitation A condition that occurs when the tricuspid valve does not totally close because the leaflets are torn or do not completely approximate in diastole.

Tricuspid Stenosis A narrowing of the orifice of the tricuspid valve.

Valve Replacement A surgical procedure in which the native valve is replaced with a mechanical or biologic prosthesis; allograft valve replacement may also be performed.

Valvuloplasty The repair of one or more components of the right (tricuspid) or left (mitral) atrioventricular valve complex that consists of the valve annulus (see Annuloplasty), the valve leaflets, the chordae tendineae, the papillary muscles, and the endoventricular wall. Occasionally, the aortic valve can be repaired, but this is performed less frequently.

Ventricular Assist Device (VAD) A mechanical device to support the left ventricle (LVAD), the right ventricle (RVAD), or both ventricles (BiVAD) can be used long term as a bridge to transplant, destination therapy, or recovery, depending on the underlying pathology. VADs decrease the workload of the heart by diverting blood from the ventricle to an artificial pump that maintains systemic (LVAD) or pulmonary (RVAD) perfusion.

Ventricular Septal Defect (VSD) Consists of a hole through the ventricular septum. VSDs may be congenital or acquired (i.e., postinfarction VSD).

Procedures

Monitoring

Monitoring (Table 35.3) of the patient’s electrocardiogram (ECG) and direct blood pressure (commonly via the radial artery in the wrist) is initiated when the patient arrives in the area designated as most appropriate (given the patient’s COVID-19 status). This may be in a preoperative or intraoperative (i.e., the operating room [OR]) area.

Table 35.3

Physiologic Monitoring

Monitoring Device	Location	Assesses/Measures
Cardiovascular System
Electrocardiogram (ECG)	Electrodes placed on shoulders, hips, and left axillary line	Electrical activity of heart: lead II useful to monitor cardiac rhythm (good visualization of P wave and QRS) and myocardial ischemia (inferior surface); lead V5 useful to detect myocardial ischemia (anterior surface)
Intra-arterial catheter	Radial artery (also femoral artery) aorta, bypass circuit; in children, may use superficial temporal or dorsalis pedis arteries; in neonates, may use umbilical artery	Direct arterial BP; blood gases; blood chemistries
Blood pressure cuff	Right or left arm	Indirect BP
CVP line	RA	RA pressure (CVP); RV filling pressure; RV preload
PA catheter (addition of fiber optics provides additional information about mixed venous oxygen saturation [SvO2])	PA (proximal and distal)	PA pressures: systolic, diastolic, mean, wedge; pulmonary vascular resistance; LV filling pressure; LV preload; CO; assessment of stroke volume, stroke work, systemic vascular resistance; mixed venous saturation (continuous indirect assessment of CO and reflection of tissue oxygenation); RV function
LA catheter (when used)	LA	LA pressure (direct); LV filling pressure; LV preload
TEE	Esophagus	Valve function before and after repair; LV wall motion, failure; intracardiac air bubbles
Urinary drainage catheter	Urinary bladder	Urinary output, renal perfusion; indirect measure of CO
Respiratory System
Mass spectrometry	Anesthesia circuit	Inspired or expired O2, CO2, and anesthetic gases; used to avoid hypoxia, hypercarbia, anesthetic overdose
Pulse oximeter	Finger or toe cot; earlobe, nose	Oxygen saturation of arterial hemoglobin; tissue oxygenation
Capnography	Anesthesia circuit	End-tidal CO2; used to detect integrity of anesthesia circuit; avoid disconnections of monitor, endotracheal tube; detect spontaneous ventilation, rebreathing, obstructive pulmonary disease
Central Nervous System
Temperature	Esophagus, nasopharynx, urinary bladder, rectum, ventricular septum, bypass circuit, PA catheter	Core, and peripheral temperature of heart, brain, and other organs
Electroencephalogram	Scalp electrodes	Detect cerebral ischemia, embolus; indication of depth of anesthesia
Renal System
Urinary discharge catheter	Bladder	Urinary output; indirect measure of cardiac output

BP, Blood pressure; CO, cardiac output; CVP, central venous pressure; LA, left atrial; LV, left ventricle; PA, pulmonary artery; RA, right atrial; RV, right ventricular; TEE, transesophageal echocardiography.

From Bojar RM. Manual of Perioperative Care in Adult Cardiac Surgery. 6th ed. Hobokon, NJ: John Wiley & Sons; 2021; Dabbagh A, Esmailian F, Aranki S. Postoperative Critical Care for Adult Cardiac Surgical Patients. 2nd ed. New York, NY: Springer; 2018; Khan MS, Yamashita K, Sharma V, Ranjan R, Dosdall DJ. RNAs and gene expression predicting postoperative atrial fibrillation in cardiac surgery patients undergoing coronary artery bypass grafting. J Clin Med. 2020;9(4):1139; Kotfis K, Ślozowska J, Listewnik M, Szylińska A, Rotter I. The impact of acute kidney injury in the perioperative period on the incidence of postoperative delirium in patients undergoing coronary artery bypass grafting—observational cohort study. Int J Environ Res Public Health. 2020;17(4):1440.

Central lines are usually inserted after transport into the OR. Whether the patient first undergoes intubation before insertion of central lines (i.e., central venous pressure, pulmonary artery catheter) or after line insertion is at the discretion of the anesthesia provider; the sequence varies among institutions. Increasingly, an anesthesia provider inserts a transesophageal echocardiography (TEE) probe routinely to illustrate cardiac function in patients undergoing valve surgery and patients with compromised LV function.⁷

Incisions

After the patient has been anesthetized, positioned, and washed (prepped), the chest is opened. The most common chest incision in cardiac surgery is the median sternotomy, the preferred incision when a thorough assessment of, and complete access to, the heart (as with multivessel CAD) is needed. However, ministernotomy, right or left anterolateral or posterolateral thoracotomy incisions, or transverse sternotomy may also be used (Fig. 35.1). The surgeon splits the sternum with a saw from the sternal notch to the xiphoid process. After the sternum is opened, the exposed pericardial sac is incised anteriorly, and the pericardial edges are tacked up along the chest wall incision to allow complete access to the entire pericardium without the necessity of entering the pleural cavities. Minimally invasive surgery uses smaller incisions and can speed patient recovery, enable the patient to return faster to normal activities, and reduce costs.

A) Full incision is made on the sternum.B) Small incision is made at the center of sternum. C) Incision is made between second and third rib on the right of sternum. D) Partial incision is made at the base of sternum. E) Small incision is made at the top of sternum. F) Incision is made to the left between ribs at the base of sternum.

Cardiopulmonary Bypass (CPB)

Systemic venous return to the heart flows by gravity drainage (the level of the patient needs to be above that of the bypass machine to facilitate drainage) into one or two large-bore (e.g., 32F to 36F) cannulas inserted into the right atrium (RA). With the single two-stage cannula (Fig. 35.2), openings in the distal tip drain blood returning from the inferior vena cava (IVC), and openings in the middle portion of the cannula drain venous blood from the superior vena cava (SVC) and the coronary circulation exiting from the coronary sinus. Some blood enters the RA and the pulmonary circulation. With double cannulation (Fig. 35.3), individual cannulas are inserted into the IVC and the SVC, thereby forcing almost all venous return into the cannulas. Generally, the two-stage cannula is used for coronary artery bypass grafting (CABG) and aortic valve surgery when total right-side decompression is not generally needed and blood entering the right side of the heart does not obscure the surgical field. Individual (double) venous cannulation can be used for procedures in the right side (e.g., tricuspid valve repair) to keep the right heart free of blood. Occasionally, two cannulas can be used when greater decompression of the RA is necessary (e.g., to improve visualization of the left atrium [LA] during mitral valve surgery).

After the blood is oxygenated, it is pumped into the systemic circulation via an arterial cannula, commonly located in the aorta (see Fig. 35.3). When aortic pathology (e.g., aortic aneurysm) makes aortic cannulation risky, the femoral artery can be cannulated (retrograde flow) for arterial return. The axillary artery may be needed when the aorta or both of the femoral arteries are unavailable.

In addition to the standard cannulation techniques for CPB, minimally invasive systems use endovascular catheters (Fig. 35.4). A venous catheter is inserted into the femoral vein, and the arterial cannula is placed into the femoral artery. The ipsilateral femoral artery is also used for insertion of a multi-lumen catheter. One lumen serves as an endovascular cross-clamp that occludes the aorta with inflation of an intra-aortic balloon at the tip of the catheter, and the other lumen can be used for infusion of antegrade cardioplegia. Pressure lines, venting catheters, and a coronary sinus retrograde cardioplegia catheter can be inserted via the jugular vein. This system does not require median sternotomy and is an important adjunct for minimally invasive surgery (such as robotic surgery).⁸

Front view of body shows retrograde cardioplegia infusion port with coronary sinus pressure monitoring lumen, Balloon inflation lumen, E C S C, and E P V inserted through neck region. Antegrade infusion port-aortic root vent with Balloon inflation lumen, Aortic root pressure monitoring lumen, and E A C inserted through lower abdomen area. The other labels are as follows: E A C, E P V, hemostatic valve, femoral artery, arterial line, and venous line., Heart shows endoaortic clamp in aorta, endopulmonary vent in left atrium, endocoronary sinus catheter in right atrium, and endovenous drainage cannula in right atrium through superior vena cava.

Front view of body shows retrograde cardioplegia infusion port with coronary sinus pressure monitoring lumen, Balloon inflation lumen, E C S C, and E P V inserted through neck region. Antegrade infusion port-aortic root vent with Balloon inflation lumen, Aortic root pressure monitoring lumen, and E A C inserted through lower abdomen area. The other labels are as follows: E A C, E P V, hemostatic valve, femoral artery, arterial line, and venous line., Heart shows endoaortic clamp in aorta, endopulmonary vent in left atrium, endocoronary sinus catheter in right atrium, and endovenous drainage cannula in right atrium through superior vena cava.

A number of risks are associated with the use of CPB (e.g., particulate or air embolus), and some form of checklist is often used before CPB is instituted (Box 35.1) and before the patient is weaned from CPB (Box 35.2). Such checklists help to enhance the safety of CPB. In addition, the clinical sequelae of CPB can affect all body systems.^8,9 Caregivers in the postoperative period should be aware of the possible effects of CPB (Table 35.4).

Box 35.1

Checklist for Initiation of Pump

• • Heparin administered
  
• • Activated coagulation time checked and at least 350 to 400 seconds
  
• • Muscle relaxant adequate (or infusion turned on for maintenance)
  
• • Inotropic infusions turned off
  
• • Pupil symmetry assessed for later comparison (unilateral dilation may indicate unilateral carotid perfusion on cardiopulmonary bypass)
  
• • Pulmonary artery catheter (if used) pulled back 5 cm
  
• • Urinary output emptied before bypass (start anew with initiation of bypass)
  
• • Proper functioning of all monitors ensured

From Bojar RM. Manual of Perioperative Care in Adult Cardiac Surgery. 6th ed. Hobokon, NJ: John Wiley & Sons; 2021; Gunaydin S, Stammers AH. Perioperative management of COVID-19 patients undergoing cardiac surgery with cardiopulmonary bypass. Perfusion. 2020;35(6):465–473. Rothrock JC. Alexander’s Care of the Patient in Surgery, 16th ed. St. Louis, MO: Elsevier; 2019.

Box 35.2

Checklist for Weaning from the Pump

• • Patient is warm (to at least 36° C)
  
• • Heart rhythm has returned
  
• • All monitors are functioning; electrocardiogram, pulmonary artery tracing, arterial line tracing, central venous pressure reflect heart filling
  
• • Heart rate is 70 to 100 bpm (<60 bpm is reduced cardiac output; ≥120 bpm is detrimental to left ventricular filling)
  
• • Infusions are prepared as necessary
  
• • Lungs are inflated but kept out of the surgeon’s field
  
• • Pressure becomes pulsatile as ventricles fill
  
• • Blood is drawn for measurement of electrolytes, hematocrit, arterial blood gases, and activated clotting time
  
• • The surgeon clamps the venous drainage cannula and removes the cannula
  
• • Patient is off pump

From Bojar RM. Manual of Perioperative Care in Adult Cardiac Surgery. 6th ed. Hobokon, NJ: John Wiley & Sons; 2021; Gunaydin S, Stammers AH. Perioperative management of COVID-19 patients undergoing cardiac surgery with cardiopulmonary bypass. Perfusion. 2020;35(6):465–473. Rothrock JC. Alexander’s Care of the Patient in Surgery. 16th ed. St. Louis, MO: Elsevier; 2019.

Table 35.4

Effects of Cardiopulmonary Bypass

Effects	Contributing Factors
Cardiovascular System
Perioperative myocardial infarction	Inadequate myocardial protection and emboli
Low cardiac output syndrome after surgery	Preexisting heart disease, inadequate myocardial protection, alteration in colloidal osmotic pressure, left ventricular dysfunction, hypoperfusion injury, hypothermia, long pump run
Increased afterload	Catecholamine release
Hypertension	Elevated renin, angiotensin, and aldosterone levels
Hypotension	Postoperative diuresis, sudden vasodilation (rewarming), third spacing
Pulmonary System
Respiratory insufficiency	Alterations in colloidal osmotic pressure, interstitial pulmonary edema, decreased perfusion, alterations in ventilatory patterns, decreased surfactant production, pulmonary microemboli
Atelectasis	Lung deflation during bypass, decreased surfactant, supine positioning; also, complement activation and inflammatory response, emboli, alveolar-capillary membrane damage
Neurologic System
Cerebrovascular accident	Cerebral emboli
Transient motor defects	Decreased cerebral blood flow
Cerebral hemorrhage	Systematic heparin administration
Neuropsychological deficits	Microemboli, ischemia, altered perfusion flow of bypass
Gastrointestinal System
Gastrointestinal bleeding	Hormonal stress and coagulation diatheses
Intestinal ischemia or infarction	Emboli and decreased perfusion
Acute pancreatitis	Pancreatic vasculature emboli
Renal System
Acute renal failure	Decreased renal blood flow, microemboli, and myohemoglobin release
Hemoglobinuria	Red blood cell hemolysis
Fluid and Electrolyte Balance
Interstitial edema, weight gain	Increased extravascular fluid and organ dysfunction, fluid shifts, decreased plasma protein concentration, increased capillary permeability
Intravascular hypovolemia	Decreased intravascular volume, bleeding, and interstitial edema
Hypokalemia	Dilution, polyuria, intracellular shifts of potassium ions
Hyperkalemia	Potassium cardioplegia and increased intracellular exchange of glucose and potassium, cellular destruction
Hyponatremia, hypocalcemia, and hypomagnesemia	Dilution, fluid shifts, diureses
Endocrine System
Water and sodium retention	Increase in antidiuretic hormone
Hypothyroidism	Initially decreased postoperative levels of thyroxine (T4), returning to normal within 24 hours, and decreased levels of triiodothyronine (T3) and thyroid-stimulating hormone
Hyperglycemia	Depressed insulin response, stimulation of glycogenesis
Immune System
Infection	Exposure to multiple pathogens (possible COVID viral particles), decreased immunoglobin levels, and hypothermia
Postperfusion syndrome	Release of anaphylactic toxins, complement activation
Hematologic Factors
Bleeding	Blood cell hemolysis, heparin rebound, reduction in platelet count and coagulation factors, coagulopathy, systemic heparin administration, depressed liver function from hypothermia

From Bainbridge D, Cheng D. Early extubation and fast-track management of off-pump cardiac patients in the intensive care unit. Semin Cardiothorac Vasc Anesth. 2015;19(2):163–168; Bojar RM. Manual of Perioperative Care in Adult Cardiac Surgery. 6th ed. Hobokon, NJ: John Wiley & Sons; 2021; Engelman DT, Lother S, George I, et al. Adult cardiac surgery and the COVID-19 pandemic: aggressive infection mitigation strategies are necessary in the operating room and surgical recovery. Ann Thorac Surg. 2020;110(2):707–711; Kaplow R, Hardin SR. Cardiac Surgery Essentials for Critical Care Nursing. 3rd ed. Burlington, MA: Jones & Bartlett Learning; 2020.

CPB is not always required. So-called off-pump procedures for myocardial revascularization can be performed while the heart is beating with the use of special devices to isolate the section of the coronary artery to be grafted; patients with a heavily calcified aorta are candidates so that the surgeon can avoid clamping a calcified aorta and risking dislodging a calcium particle that can embolize to the brain. For procedures that require entry into the chambers of the heart (e.g., valve replacement), CPB and myocardial protection are necessary for perfusion of the body, avoidance of air emboli that originate from the open cardiac chamber, and myocardial preservation.

Myocardial Protection

The goal of myocardial protection is to conserve cardiac energy resources; the goal is achieved with induced hypothermia and rapid diastolic arrest. Hypothermia reduces the metabolic rate (and therefore the energy demands) of the tissue being cooled, thereby conserving the heart’s energy resources for the resumption of work once the heart starts to beat again.

For most cardiac procedures of less than 1 hour of induced cardiac arrest (e.g., CABG), the perfusionist cools the systemic circulation from a normal temperature of 37° C (98.6° F) to approximately 34° C (93.2° F). The cardioplegia solution is cooled to a lower temperature for intracardiac cooling as a method of myocardial protection. For procedures with a longer cross-clamp time, the systemic temperature may be further reduced to protect the brain, kidneys, and other organs while the heart is arrested by reducing energy demands and limiting ischemic injury. Topical cooling of the heart with cold lavage or frozen “slush” placed on the heart and in the pericardial well helps to achieve transmural cooling.9

Although induced hypothermia plays an important role in minimization of tissue ischemia during selected portions of cardiac procedures, inadvertent hypothermia has become an important consideration for cardiac patients because of associated risks for perioperative complications. Before surgery, shivering increases myocardial oxygen demands and further taxes hearts that have diminished myocardial energy supplies. During surgery, before and after CPB, inadvertent cooling of the patient is associated with increased surgical bleeding and a diminished immune response. After surgery, hypothermia contributes to patient discomfort, impaired wound healing, prolonged bleeding, longer lengths of stay, and cardiac events such as ischemia and tachyarrhythmias.² Preoperative active warming measures—such as the application of forced warm air—are less likely to be used in order to minimize potential viral contamination. During the intraoperative period (before and after induced hypothermia) and the postoperative period, warming devices that do not use forced air (such an electrically warmed blankets) may be used. Intravenous fluid warmers are important devices for maintaining an appropriate patient temperatue.⁷

Rapid diastolic arrest conserves existing cellular energy resources (e.g., adenosine triphosphate/ATP) by avoiding the energy-expensive state of ventricular fibrillation before the heart achieves an arrested state. Quick arrest of a beating heart (e.g., 10–20 seconds) enhances myocardial energy conservation. Potassium is the most commonly used arresting agent, but the solutions may also contain electrolytes, buffers to maintain appropriate pH, glucose, metabolic substrates, calcium antagonists, tromethamine, heparin, and antiarrhythmic agents. The carrying solution can be crystalloid or blood (preferable for its oxygen-carrying capacity).^8,9

Methods of infusing cardioplegia include the antegrade and retrograde routes and the direct coronary ostial route of infusion. With the antegrade method, a needle catheter is inserted into the anterior aorta proximal to the aortic cross-clamp (see Fig. 35.2). The cardioplegia solution is infused with sufficient pressure to close the aortic valve. With the cross-clamp applied distally and a competent aortic valve proximally, the only paths for the solution to travel are the right and left coronary ostia lying between the cross-clamped aorta and the closed aortic valve. In patients with aortic valve insufficiency, cardioplegia flow into the coronary ostia is significantly reduced because the incompetent aortic valve provides a lower pressure pathway into the inner ventricular chamber, thereby distending the heart and increasing myocardial wall tension. Retrograde delivery is indicated in the presence of coronary artery lesions that impair the transmural distribution of the cardioplegia when delivered solely by the antegrade route. For the retrograde route, the surgeon inserts a catheter through a stab wound into the right atrial wall and threads the catheter into the coronary sinus. The cardioplegic solution infused into the coronary sinus flows retrograde through the cardiac veins and arteries. The solution exits via the coronary ostia, where it is removed by suction.⁹

In addition to thermal and pharmacologic interventions, other strategies to achieve adequate myocardial energy conservation include implementing actions that consistently maximize myocardial energy supplies and minimize myocardial energy demands. Surgeons and assistants use caution in touching the heart before bypass to lessen the risk of ventricular fibrillation. Anesthesia providers pharmacologically decrease cellular oxygen demand and increase cellular oxygen supply. Other considerations in protecting the heart and preventing error include minimization of cross-clamp time with availability of the appropriate supplies and equipment, a plan for surgery (jointly developed by surgeons, anesthesia providers, perfusionists, and nursing personnel), anticipation and ability to respond to potential risks and complications applicable to one’s professional responsibilities and skills, implementation of safety procedures, and frequent and collaborative communication.

Surgery for Coronary Artery Disease

CAD remains a leading cause of death among men and women, although Peters and colleagues10 found that a combination of obesity and COVID-19 infection has a higher mortality. Left heart cardiac catheterization is commonly performed to identify areas affected by obstructive atherosclerotic CAD. Selective coronary angiography with an injection of contrast medium into the right and left coronary ostia illustrates coronary anatomy, distal coronary perfusion, the location of atherosclerotic lesions, the status of coronary collateral circulation, and the percentage of narrowing of coronary arteries affected by CAD. Dye is injected into the LV (ventriculography) to determine wall motion (e.g., hypokinesia, dyskinesia, paradoxical motion), and valvular function (e.g., mitral regurgitation [MR], prosthetic valve function). Generally, a right heart catheterization yields data concerning the IVC and SVC, the RA and ventricle, tricuspid and pulmonary valves, and the pulmonary vasculature.¹¹

Percutaneous coronary interventions, specifically angioplasty with stent insertion, can be performed for discrete coronary lesions. Complications from the interventional procedure include prolonged chest pain, myocardial infarction (MI), coronary spasm, or coronary artery dissection that can necessitate emergency CABG. Evidence supports surgical revascularization (i.e., CABG) over percutaneous coronary interventions in patients with three-vessel and left main CAD.¹¹

When CABG is recommended for patients, the number and types of bypass grafts (e.g., saphenous vein, internal mammary artery [IMA]) are assessed. Fig. 35.5 illustrates possible arterial and venous autologous conduits. Grafts from cadaver human saphenous vein and human and bovine umbilical vein and synthetic grafts have been used when other conduits were unavailable.

Human shows heart along with arteries and veins highlighted. The associated labels are as follows: Left internal mammary artery, left cephalic vein, celiac artery, splenic artery, superior mesenteric artery, inferior mesenteric artery, internal iliac artery, left basilic vein, lesser saphenous vein, greater saphenous vein, radial artery, external iliac artery, inferior epigastric artery, gastroepiploic artery, superior epigastric artery, right cephal

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