Recording the right atrial electrogram through the fluid column of a pulmonary artery catheter.

Analysis of the cardiac rhythm in patients with ventricular and supraventricular tachycardia can be difficult because P-waves tend to be obscured by other components of the ECG. Recording of the intracavitary electrogram by means of pacing wires and the use of esophageal leads can be very helpful under these circumstances. Because a number of these patients are monitored with pulmonary artery catheters, we developed a method to obtain the atrial electrogram using the fluid column of the pulmonary artery catheter as an electrical conductor. Only slight modifications of the ECG equipment were necessary.