Ruth N. Klepfer

Acute Effects of Biventricular Pacing in Heart Failure Patients with a Normal Ejection Fraction and Mechanical Dyssynchrony

Objectives: We tested the acute effects of resynchronization in heart failure patients with a normal (>50%) left ventricular (LV) ejection fraction (HFNEF) and mechanical dyssynchrony. Methods: Twenty-four HFNEF patients (72 ± 6 years, 5 male) with mechanical dyssynchrony (standard deviation of electromechanical time delay among 12 LV segments >35 ms) were studied with temporary pacing catheters in the right atrium, LV, and right ventricle (RV), and high-fidelity catheters for pressure recording. Using selected atrioventricular (AV) intervals of 60, 90, 120, 150, and 180 ms to optimize transmitral flow during simultaneous biventricular pacing, the RV-LV (VV) interval was then evaluated at RV30, RV15, 0, LV15, LV30, and LV45 (RV or LV indicates which ventricle was paced first, the number indicates by how many ms). Results: During simultaneous pacing, longer AV intervals were associated with improved LV pressure-derivative minimums and increased aortic pressures (p < 0.05 vs. normal sinus rhythm). In the VV interval from RV30 to LV45, there was a graded increase in the aortic velocity time integral and a decrease in dyssynchrony during simultaneous or LV-first pacing (p < 0.05 vs. normal sinus rhythm). Conclusions: For HFNEF patients with mechanical dyssynchrony, acute simultaneous biventricular or LV-first pacing with longer AV intervals reduced mechanical dyssynchrony and improved diastolic and systolic hemodynamics.

Acute electromechanical effects of atrioventricular coupled pacing in patients with heart failure.

BACKGROUND Postextrasystolic potentiation (PESP) is a property of cardiac tissue whereby two closely timed depolarizations cause the subsequent contraction to be of increased magnitude. METHODS AND RESULTS Ten subjects were studied in a single-blind study to evaluate the safety and performance of an atrioventricular coupled pacing (A-VCP) algorithm to produce sustained PESP among subjects with moderate heart failure. The primary end points were algorithm safety, patient perception, and cardiac function. The effects of A-VCP on cardiac function were assessed by comparing echocardiographic parameters before and after 15 to 20 minutes of A-VCP. A-VCP produced no arrhythmic episodes, ejection fraction increased by 8 ejection fraction points (31%) (P < or = .001), end-systolic volume decreased by 10% (P < or = .05), and a trend toward increasing end-diastolic volume was observed (P = .084). Stroke volume increased by 43% (P < or = .001), and the pulse rate decreased by 41% (P < or = .001) during A-VCP. This resulted in decreased cardiac output of 15% (P < or = .05). Six of the 10 subjects felt no effects from A-VCP, and four subjects felt a change with A-VCP turned on. CONCLUSION Short-term A-VCP was found to be safe and well tolerated in a majority of patients. Hemodynamic effects were mixed with improved ejection fraction and stroke volume but decreased cardiac output.