TABLE 35-1 Etiologies of Cardiac Tamponade | ||||||||||||
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TABLE 35-2 Clinical Presentation of Pericardial Disorders | ||||||||||||||||||||||||||||||||
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Neoplastic Cardiac Tamponade
Neoplastic Cardiac Tamponade
Brenda K. Shelton
I. Definition:
Cardiac tamponade is a syndrome of pericardial constriction that does not permit the normal expansion of the heart, impeding venous blood return and ventricular filling.
A. Intrapericardial pressure is normally subatmospheric, allowing the inflow of low-pressure venous blood into the right heart. When the pericardium is constricted by fibrous bands or filled with fluid, the pressure in the pericardial sac is raised to a level that exceeds the normal filling pressure of the ventricle.
1. The initial pathophysiology is venous congestion caused by obstruction to inflow of blood into the heart.
2. When ventricular filling is more severely impaired, there is no blood inflow and, therefore, no subsequent cardiac output. This is called cardiac tamponade.
B. Three terms are used to describe the clinical conditions of increased intrapericardial pressure typical of this syndrome.
1. Pericarditis is an inflammation of the lining surrounding the heart that may be fibrous or exudative.
2. Pericardial effusion refers to excessive fluid accumulation within the pericardial sac and involves serous, purulent, bloody, or malignant exudates.
3. Pericardial tamponade (cardiac tamponade) is fluid accumulation in the pericardial sac that is so great that normal contraction and ejection capabilities fail.
II. Etiology:
The etiologies of pericardial tamponade depend on the mechanism of action or type of exudate. For a listing of common etiologies of tamponade according to their pathophysiologic mechanism, see Table 35-1.
A. Transudative effusions are due to alterations in capillary permeability.
B. Exudative effusions occur due to malignant cell invasion of the pericardium.
C. Traumatic injury causes hemorrhagic tamponade (which rarely occurs in cancer patients).
D. Infectious diseases (not the usual etiologic factor): Fluid collection related to infection may be purulent and harboring infective organisms, or serous and related to the inflammatory response of the pericardium.
III. Patient Management
A. Assessment
1. Signs and symptoms may depend on the type of pericardial disorder or may be a reflection of the chronicity of the problem.
a. For differentiation of signs and symptoms according to their relation to pericarditis, effusion, or tamponade, see Table 35-2.
b. Rapidly developing effusions may present symptomatically with minimal fluid accumulation (ie, 50 to 80 mL).
c. Patients with slow-developing effusions compensate for a lower cardiac output and may not demonstrate signs or symptoms until there is more than 1,000 mL of fluid accumulation.
2. Inflammation of the pericardium often causes pain in the chest that is exacerbated by movement, deep breathing, or lying flat. When pericarditis without fluid is present, pain is most severe, sharp, and localized. This severe discomfort may be partially relieved by sitting up and leaning forward, which displaces the heart within the chest and allows freer movement for ventricular filling. As an effusion develops, the pain becomes more dull and diffuse, but less positional. When tamponade is present, pain is more often described as chest heaviness, or pain is not present at all.
3. Pericardial rub or muffled heart sounds are revealed on cardiac auscultation.
a. A pericardial rub is an abrasive scratching sound heard throughout systole and diastole. It may be auscultated at any anatomic site because it reflects inflammation or irritation between the myocardium and pericardial sac. Most pericardial rubs are heard best at the apex when the patient is lying down, and at the base of the heart when the patient is sitting up and leaning forward. Having the patient lie on the left side to facilitate the heart’s shift toward the chest wall may also make this abnormal sound more discernible.
b. Muffled or distant heart sounds are noted when excess pericardial fluid diffuses the normal valve closure sounds. Muffled heart sounds do not always indicate cardiac effusion or tamponade; they also occur with large people, barrel-chested people, severe pleural effusions, or with poor cardiac function.
4. Displacement of the point of maximal impulse (PMI) of the heart reflects an enlarged heart with the strongest contraction at the apex being shifted.
a. The PMI is usually located in the fifth intercostal space, along the midclavicular line.
b. In pericardial effusion and tamponade, the PMI reflects the larger cardiac diameter and is shifted to the left (toward the axilla) or downward (toward the sixth intercostal space).
5. The strength of the central and peripheral pulses will be diminished according to the degree of compromised cardiac output.
a. In pericarditis and effusion, the cardiac output is decreased, but it first feeds the proximal branches of the aortic arch that perfuse the brain and upper extremities.
b. As a consequence, head (carotid) and upper extremity (brachial, radial) pulses will be stronger than lower extremity pulses (femoral, pedal).
c. This differs from other decreased cardiac output states where the femoral pulse is usually stronger than the radial pulse.
6. Jugular venous pressure (JVP) increases due to resistance to flow of blood into the heart. The waves of JVP can be seen by examining the neck above the midclavicular line and by measuring the number of centimeters the wave extends above the clavicle when the patient is in a semi-Fowler’s position. These pulsations can be so prominent as to produce a large continuous wave up the neck to the chin (called cannon a wave) when cardiac tamponade is present. Jugular venous distention (JVD), often referred to as bulging neck veins, is present bilaterally in severe effusion or impending tamponade.
a. The amount of venous pressure may also be measured by right atrial (RA) or central venous pressure (CVP) readings.
b. In pericardial effusion and tamponade, the RA pressure will exceed 6 mmHg (transduced pressure) or 10 cm of water (water manometer).
7. Peripheral edema, hepatomegaly, and splenomegaly are other symptoms of venous congestion that may be present, particularly if the onset of effusion or tamponade is insidious.
8. Cough is only present with pericardial effusion if the backflow of venous blood and congestive heart failure are prominent features.
9. Hypotension occurs in effusion and tamponade because of decreased cardiac output and increased vascular resistance due to a sympathetic vasoconstriction.
a. First, the diastolic pressure rises; then the systolic pressure decreases.
b. Patients usually have a narrow pulse pressure (systolic and diastolic pressures are nearly equal) due to equalization of the pressure within and around the heart.
c. The presence of a pulsus paradoxus >10 mmHg signifies resistance to the inflow of blood into the heart. Pulsus paradoxus may be present in less severe conditions of increased thoracic pressure, such as with chronic lung disease; however, it is rarely absent in impending cardiac tamponade. Of clinical significance is that the lower systolic blood pressure is the actual perfusing blood pressure (see Interventions in Section III.D.1.b).
d. Cardiac dysrhythmias are almost always present, although the prevalent pathophysiologic manifestations predict whether tachycardia or bradycardia is present.
e. Tachycardia is the first heart rate response to decreased cardiac output and is considered an early symptom.
f. Patients with impending tamponade will have such high thoracic resistance that blood does not fill the ventricles or the coronary arteries during inspiration, and bradycardia, heart block, or short periods of asystole may occur during the inspiratory phase of breathing.
10. Dyspnea occurs due to poor lung blood flow and compromised oxygen exchange or occurs with the congestion present with obstructed venous return. It is the most common, although the least specific, symptom.
11. Alterations in mental status may be present if blood flow to the brain is impaired.
12. Oliguria is often an early indicator of compromised cardiac output.
B. Diagnostic Parameters: There are no laboratory or urine tests used to diagnose neoplastic cardiac tamponade; however, there are other tests that can indicate the presence of the condition.
1. Echocardiogram analysis will show fluid in the pericardial sac and distorted or inadequate ventricular expansion. In impending tamponade, one or both ventricles are collapsed/closed due to high intrapericardial pressure (van Steijn, et al, 2002).
2. Chest x-rays show symmetric cardiac enlargement, with the cardiac diameter exceeding half the chest, with a water bottle silhouette of the heart, and with clear lung fields.
