Profound bradycardia following release of cardiac tamponade. Hypothesis for reflex control

A 58-year-old patient with chronic renal failure presented for routine hemodialysis, and was noted to have severe hypotension and findings on examination compatible with cardiac tamponade. The patient had emergency construction of a pericardial window. At the time of surgery, rapid evacuation of the pericardial space resulted in rebound hypertension associated with marked bradycardia. The features of the patient's case were analogous to the cardiovascular and reflex adjustments that normally occur during the Valsalva maneuver. These findings suggest that the cardiovascular changes occurring during the rapid decompression of cardiac tamponade may be reflexly-mediated, and gradually decompression of the pericardial space is therefore recommended to avoid reflex hypertension and bradycardia.