Hemodynamic findings in heart block with slow ventricular rates

Abstract

Six patients with acquired heart block and ventricular rates below 40 per minute were catheterized. Pertinent hemodynamic findings were: (1) elevated right atrial and right ventricular systolic pressure; (2) atrial systolic waves transmitted to both the right ventricle and main pulmonary artery successively; (3) giant atrial a waves occurring at the time of simultaneous atrioventricular systoles, but not when this occurred in or near early diastole of the preceding ventricular beat; (4) systolic pulmonary hypertension; (5) reduced mean brachial artery pressure, but elevated mean pulmonary artery pressure; (6) increased total vascular resistance of both the pulmonic and systemic circulations; (7) reduced oxygen consumption; (8) reduced cardiac index; and (9) increase of stroke index to 28 per cent or less above normal in four of the six patients. The injection of Isuprel via a catheter directly into the main pulmonary artery in two patients resulted in: (1) more rapid ventricular rate; (2) conversion to a sinus rhythm in one; (3) unaltered stroke volume; (4) increased cardiac output; (5) unaltered oxygen consumption; (6) decreased arteriovenous oxygen difference; and (7) decreased total vascular resistance in both the pulmonic and systemic circulations.