Low pressure cardiac tamponade: diagnosis facilitated by Doppler echocardiography.

A case of low pressure cardiac tamponade is reported in which hypovolaemia altered the clinical findings of tamponade and complicated the diagnosis. Venous pressure was not raised and there was no pulsus paradoxus. In this patient, a man of 67, characteristic variations in diastolic inflow signals and the isovolumic relaxation period throughout the respiratory cycle were shown by Doppler echocardiography and led to the diagnosis of cardiac tamponade in the absence of characteristic signs and symptoms.