In a patient with severe left ventricular (LV) systolic dysfunction and permanent dual-chamber pacemaker, Doppler cardiographic LV stroke volume was measured at rest and during exercise at 4 different atrioventricular (AV) delays (60, 80, 100, and 160 msec). Maximum stroke volume of 49 ml (cardiac output 4.1 L/min) was obtained at an AV delay of 80 msec at rest. Similarly, an AV delay of 80 msec resulted in maximum stroke volume of 54 ml during exercise (cardiac output 5.8 L/min). The increased stroke volume at rest and during exercise at an AV delay of 80 msec was primarily due to longer diastolic filling time, higher atrial filling fraction, and lower mitral regurgitant fraction. Thus, the beneficial effects of an optimal AV delay on resting hemodynamics in LV systolic failure appears to be sustained during exercise and may explain improved exercise tolerance in some patients with dual-chamber pacing.
|Original language||English (US)|
|Number of pages||4|
|State||Published - Dec 1 1995|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine