Cardiac tamponade is a life-threatening condition that can be palliated or cured, depending on its cause and on the timeliness of treatment. Making a timely diagnosis and providing the appropriate treatment can be gratifying for both patient and physician.
Cardiac tamponade occurs when fluid in the pericardial space reaches a pressure exceeding central venous pressure. This leads to jugular venous distention, visceral organ engorgement, edema, and elevated pulmonary venous pressure that causes dyspnea. Despite compensatory tachycardia, the decrease in cardiac filling leads to a fall in cardiac output and to arterial hypoperfusion of vital organs.
PEARL 1: SLOW ACCUMULATION LEADS TO EDEMA
The rate at which pericardial fluid accumulates influences the clinical presentation of cardiac tamponade, in particular whether or not there is edema. Whereas rapid accumulation is characterized more by hypotension than by edema, the slow accumulation of pericardial fluid affords the patient time to drink enough liquid to keep the central venous pressure higher than the rising pericardial pressure. Thus, edema and dyspnea are more prominent features of cardiac tamponade when there is a slow rise in pericardial pressure.
PEARL 2: EDEMA IS NOT ALWAYS TREATED WITH A DIURETIC
Edema is not always treated with a diuretic. In a patient who has a pericardial effusion that has developed slowly and who has been drinking enough fluid to keep the central venous pressure higher than the pericardial pressure, a diuretic can remove enough volume from the circulation to lower the central venous pressure below the intrapericardial pressure and thus convert a benign pericardial effusion to potentially lethal cardiac tamponade.
One must understand the cause of edema or low urine output before treating it. This underscores the importance of the history and the physical examination. All of the following must be assessed:
- Symptoms and time course of the illness
- Concurrent medical illnesses
- Neck veins
- Blood pressure and its response to inspiration
- Heart sounds
- Heart rate and rhythm
- Abdominal organ engorgement
- Edema (or its absence).
PEARL 3: UNDERSTANDING THE CAUSE IS ESSENTIAL
Understanding the cause of cardiac tamponade is essential.
A trauma patient first encountered in the emergency department may have an underlying disease, but the focus is squarely on the effects of trauma or violent injury. In a patient with multiple trauma, hypotension and tachycardia that do not respond to intravenous volume replacement when there is an obvious rise in central venous pressure should be clues to cardiac tamponade.1
If the patient has recently undergone a cardiac procedure (for example, cardiac surgery, myocardial biopsy, coronary intervention, electrophysiologic study with intracardiac electrodes, transvenous pacemaker placement, pacemaker lead extraction, or radiofrequency ablation), knowing about the procedure narrows the differential diagnosis when hypotension, tachycardia, and jugular venous distention develop.