Adverse pacemaker hemodynamics evaluated by pulmonary venous flow monitoring.

The pacemaker syndrome refers to symptoms and signs in the pacemaker patient caused by an inadequate timing of atrial and ventricular contractions. The lack of normal atrioventricular synchrony may result in a decreased cardiac output and venous cannon A waves. The objective of this study was to define the left atrial and pulmonary venous flow response to ventricular pacing in a group of 14 unselected consecutive patients with total heart block and sinus rhythm. Pulmonary venous flow was assessed by transesophageal pulsed Doppler echocardiography in the VVI and DDD pacing modes. An inappropriate atrial timing caused a marked augmentation of the normally small pulmonary venous z wave in all patients ("negative atrial kick," peak z wave in DDD pacing 14.5 +/- 4.6 cm/s, VVI pacing 51.8 +/- 15.0 cm/s). Restoration of AV synchrony (DDD pacing, AV interval 100 ms) abolished these "cannon z waves" in all patients, and a normal pattern of pulmonary venous flow was achieved. Abnormal pulmonary venous flow characteristics were observed in 2 of 14 patients during DDD pacing with short AV intervals (100 ms). The Doppler pattern was similar to the findings seen in VVI pacing. Assessment of pulmonary venous flow by transesophageal pulsed Doppler echocardiography may provide a simple, sensitive, and relatively noninvasive technique to evaluate patients with suspected pacing induced adverse hemodynamics.