A number of patients who undergo hemodynamic monitoring may have or develop some form of atrial or ventricular conduction disturbance or block. Potentially, many of these patients could benefit from temporary pacing of the right ventricle and/or atrium. Following institutional approval and with informed patient consent, a balloon flotation pulmonary artery type catheter with atrial and ventricular pacing capabilities utilizing either a transluminal atrial bipolar pacing probe, a Chandler transluminal ventricular pacing probe, or both together was tested in five patients. Currents required for stable pacing were compared with those obtained using atrial and ventricular epicardial wires placed at the time of cardiac surgery procedures requiring cardiopulmonary bypass. Results of these two pacing techniques were compared by regression analysis, and no significant differences were found between the two methods. The catheter was found to be clinically useful, and stable atrial, ventricular, and atrioventricular sequential pacing was instituted in all but one situation during which the patient developed intractable atrial fibrillation following bypass resistant to any pacing therapy. It is concluded that the test catheter is a reliable, clinically useful device that provides considerable advantages over currently available temporary pacing systems using pulmonary artery catheters.