Pericardial effusion with tamponade physiology
This patient is presenting with low arterial pressure, distended jugular veins, and distant heart sounds. These are the components of Beck’s triad, which is highly suggestive of cardiac tamponade.1 A 12-lead electrocardiogram revealed low voltages. A 2-dimensional echocardiogram shortly after the chest x-ray showed a very large pericardial effusion with a swinging heart, inferior vena cavadilatation with loss of respiratory variation, and right atrial and ventricular diastolic collapse, all of which are features of tamponade and hemodynamic instability.2
The patient was immediately taken to the cardiac catheterization lab, where a pericardiocentesis was performed and 1.5 L of bloody fluid was removed. The patient experienced immediate improvement of his hemodynamic status and complete resolution of his symptoms. Cytology of the pleural fluid was consistent with poorly differentiated adenocarcinoma.
Although imaging is helpful and easily obtainable in the diagnosis of cardiac tamponade, it is not always necessary to make the diagnosis. The clinical diagnosis can often be made at bedside. While Beck’s triad described above should increase the suspicion for tamponade physiology, it may be absent in many cases.1
Other signs include Kussmaul’s sign, in which the jugular veins become more distended with inspiration, and pulsus paradoxus, in which there is a 10-mm Hg drop in systolic blood pressure with inspiration. Inspiration during tamponade results in increased venous return, which improves right atrial and ventricular filling. However, because of extrinsic compression on the heart by the pericardial effusion, the ventricles cannot expand to accommodate the increased volume. As a result, there is a shift of the interventricular septum to the left, which decreases the left ventricular end diastolic volume and consequently the stroke volume and cardiac output.3
That decrease in cardiac output is manifested by a drop in systolic blood pressure. Pulsus paradoxus can be difficult to measure because of misconceptions about how to measure it.
- Beck CS. Two cardiac compression triads. JAMA. 1935;104(9):714-716.
- Tamponade. Echocardiography in ICU. Stanford University. https://web.stanford.edu/group/ccm_echocardio/cgi-bin/mediawiki/index.php/Tamponade. Accessed August 16, 2017.
- Pulsus paradoxus & blood pressure measurement. Stanford Medicine 25. An Initiative for bedside medicine. https://stanfordmedicine25.stanford.edu/the25/bppp.html. Accessed August 16, 2017.