In this article, we will discuss the Diagnosis of Cardiac Tamponade. So, let’s get started.
Diagnosis and Investigations
Cardiac tamponade should be suspected in a patient who appears to be in shock but has high jugular venous pressure and distended neck veins. This is especially true in setting of trauma. The physical signs of low cardiac output with silent heart, enlarged area of dullness further strengthen the diagnosis which is confirmed by demonstrating the fluid in the pericardial sac on echocardiography. The investigations that help in diagnosis are:
- Chest X-ray may show enlarged globular heart (money-bag appearance) with oligaemic lungs
- Fluoroscopy may show diminished cardiac pulsations with enlarged cardiac shadow
- The electrocardiogram may show low voltage graph, sinus tachycardia and electric alternans (QRS alternans)
- The echocardiogram shows, significant anterior and posterior echo-free space, right ventricular and right atrial cavities are reduced in diameter and there is diastolic inward motion (collapse of RV and RA free wall due to high pericardial pressure), enlarged inferior vena cava with absence of respiratory variations.
- Doppler study: The characteristic and diagnostic feature on Doppler study is the exaggerated respiratory variations in tricuspid and pulmonary valve inflow velocity. Venous flow is prominently systolic with exaggerated respiratory variations in inferior vena cava (IVC) and hepatic vein flow (diminished forward flow during expiration)
- CT or MRI: Cardiac CT or MRI may be necessary to diagnose loculated effusion responsible for cardiac tamponade
- CVP monitoring helps in the diagnosis, differential diagnosis and serves as a guide to fluid therapy. CVP is raised in pericardial effusion with shock, hence, differentiates it from hypovolemic shock where CVP is low
- Other investigations are done to find out the cause such as biochemical, microbiological (culture for DNA of M.tuberculosis by PCR) and cytological examination (RBC, WBCs) of pericardial fluid. Fluid may be transudate, exudate or bloody depending on the cause.