Cardiac Tamponade Workup

• Creatine kinase and isoenzymes: Levels are elevated in patients with myocardial infarction and cardiac trauma.
• Renal profile and CBC count with differential: These tests are useful in the diagnosis of uremia and certain infectious diseases associated with pericarditis.
• Coagulation panel: The prothrombin time and activated partial thromboplastin time are useful for determining bleeding risk during interventions, such as pericardial drainage, the placement of pericardial windows, or both.
• Antinuclear antibody assay, erythrocyte sedimentation rate, and rheumatoid factor: Although nonspecific, results from these tests may give clues to a connective tissue disease predisposing to the development of pericardial effusion.
• HIV testing: Approximately 24% of all pericardial effusions are reported to be associated with HIV infection.
• Purified protein derivative testing: This is used to diagnose tuberculosis, which is an important and not uncommon cause of pericardial effusion and tamponade.

• Chest radiography findings may show cardiomegaly, water bottle–shaped heart, pericardial calcifications, or evidence of chest wall trauma (see image below). This anteroposterior-view chest radiograph shows a massive bottle-shaped heart and conspicuous absence of pulmonary vascular congestion. Reproduced with permission from Chest, 1996: 109:825.
• Bowed catheter sign on chest radiograph in children after central venous catheter insertion may be suggestive of tamponade.^[10]
• Although echocardiography provides useful information, cardiac tamponade is a clinical diagnosis (see Clinical). The following may be observed with 2-dimensional echocardiography:

  • An echo-free space posterior and anterior to the left ventricle and behind the left atrium: After cardiac surgery, a localized posterior fluid collection without significant anterior effusion may occur and may readily compromise cardiac output.
  • Early diastolic collapse of the right ventricular free wall (See the images below.)Early diastolic collapse of right ventricular free wall (subcostal view) Early diastolic collapse of right ventricular free wall (parasternal short-axis view at aortic valve)
  • Late diastolic compression/collapse of the right atrium (See the image below.)Late diastolic collapse of right atrium (subcostal view)
  • Swinging of the heart in its sac
  • LV pseudohypertrophy
  • Inferior vena cava plethora with minimal or no collapse with inspiration (See the image below.)Dilated inferior vena cava
  • A greater than 40% relative inspiratory augmentation of right-side flow
  • A greater than 25% relative decrease in inspiratory flow across the mitral valve
• Conditions that may simulate pericardial effusion on 2-dimensional echocardiography include the following:

  • A large left pleural effusion
  • Any tumor surrounding the heart
  • Mitral annular calcification
  • A descending thoracic aorta
  • A catheter in the right ventricle
  • An enlarged left atrium
  • An annular subvalvular LV aneurysm
  • A bronchogenic cyst

• With a 12-lead electrocardiogram (see image below), the following findings are suggestive but not diagnostic of pericardial tamponade.

  • Sinus tachycardia
  • Low-voltage QRS complexes
  • Electrical alternans (also observed during supraventricular and ventricular tachycardia): Alternation of QRS complexes, usually in a 2:1 ratio, on electrocardiogram findings is called electrical alternans. This is due to movement of the heart in the pericardial space. Electrical alternans is also observed in patients with myocardial ischemia, acute pulmonary embolism, and tachyarrhythmias.
  • PR segment depressionA 12-lead electrocardiogram showing sinus tachycardia with electrical alternans. Reproduced with permission from Chest, 1996; 109:825.
• Computed tomography (CT) imaging of the heart: Gold et al reported compression of the coronary sinus as observed by CT imaging as an earlier marker for cardiac tamponade in 46% of patients.^[11]
• Pulse-oximetry: Respiratory variability in pulse-oximetry waveform noted in patients with pulsus paradoxus. In a small group of patients with tamponade, Stone et al noted increased respiratory variability in pulse-oximetry waveform in all patients.^[12] This should raise the suspicion for hemodynamic compromise. In patients with atrial fibrillation, pulse-oximetry may aid to detect the presence of pulsus paradoxus.

Swan-Ganz catheterization

• Before or after insertion of the Swan-Ganz catheter, the system must be zeroed after positioning the transducer at the midpoint of the left atrium. Then calibrate the monitoring system. Prior to insertion, test the balloon and flush all the ports. Then insert the catheter into one of the major veins. At a depth of 20 cm, inflate the balloon and slowly advance the catheter, while continuously monitoring the pressure from the distal lumen. Always deflate the balloon before withdrawing the Swan-Ganz catheter. The waveforms help indicate the position of the catheter tip if fluoroscopy is not readily accessible. At approximately the 40- to 50-cm mark, the wedge pressure is usually recorded. Secure the catheter position, and obtain a chest radiograph to confirm the position.
• In tamponade, near equalization (within 5 mm Hg) of the right atrial, right ventricular diastolic, pulmonary arterial diastolic, and pulmonary capillary wedge pressure (reflecting left atrial pressure) occurs. The right atrial pressure tracings display a prominent systolic x descent and abolished systolic y descent.
• Boltwood et al described the diastolic equalization of pulmonary capillary and right atrial pressures as predominantly inspiratory, known as the inspiratory traction sign.^[13] This is due to inspiratory traction of the taut pericardium by the diaphragm.

Occasionally, a pericardial biopsy is performed when the etiology of the pericardial effusion that caused the tamponade is unclear. This is especially useful in cases of tuberculous pericardial effusions because cultures of the pericardial fluid in these cases rarely yield a positive result for mycobacteria. However, granulomas seen on pericardial biopsy specimens are often seen in patients with tuberculous pericarditis. In general, cytopathologic findings from pericardial fluid and histologic findings from pericardial biopsy specimens depend on the underlying pathology. Cytological examination identifies etiopathological cause of tamponade in about 75% of cases.^[14]