Hemodynamic effects of atrial septal pacing in cardiac resynchronization therapy patients.

INTRODUCTION: Spontaneous or pacing-induced interatrial conduction delay may affect the outcome of heart failure patients treated with cardiac resynchronization therapy (CRT). The objective of this study was to evaluate the impact of the atrial pacing site (right atrial appendage, RAA; and low interatrial septum, LIS) during biventricular (BV) pacing on the left ventricular (LV) systolic function in candidates for CRT. METHODS AND RESULTS: Fifteen heart failure patients with left bundle branch block and LV ejection fraction < or =35% were enrolled. Electrodes were placed at the RAA, LIS, right ventricular apex, and LV free wall. A DDD protocol was tested, which consisted of 50 beats in AAI mode from the RAA followed by 50 beats in BV DDD mode with atrial pacing at the RAA (DDD_RAA) or at the LIS (DDD_LIS) at four AV delays. The average (+/-SD)%LV+dP/dtmax increase during DDD_RAA and DDD_LIS pacing with respect to baseline was 24 +/- 16% and 21 +/- 15%, respectively (P < 0.01), and average percentage change in aortic pulse pressure during DDD_RAA and DDD_LIS with respect to baseline (%PP) was 13 +/- 8% and 13 +/- 7% (ns). CONCLUSIONS: Our results show a significant hemodynamic improvement with both DDD_RAA and DDD_LIS biventricular pacing compared to AAI pacing. However DDD_LIS pacing was not superior to DDD_RAA pacing in acute hemodynamic responses.

Cardiac resynchronization therapy optimization by finger plethysmography.

OBJECTIVES: We tested a simple noninvasive method for cardiac resynchronization therapy (CRT) optimization using standard finger photoplethysmography (FPPG). BACKGROUND: CRT can increase left ventricular cardiac output in patients with heart failure and ventricular conduction delay. Optimal therapy delivery depends on an appropriate AV delay. Multiple invasive and noninvasive methods have been attempted to identify patients and the best AV delay for CRT, but all suffer from a combination of high patient risk, cost, complexity, and low reproducibility. METHODS: FPPG and invasive aortic pressure data were simultaneously collected from 57 heart failure patients during intrinsic rhythm alternating with very brief periods of pacing at 4 to 5 AV delays. After correcting data for artifacts, the median percentage responses for each AV delay were classified as positive, negative, or neutral compared to baseline (Wilcoxon rank test). RESULTS: FPPG correctly identified positive aortic pulse pressure responses with 71% sensitivity (95% CI: 60-80%) and 90% specificity (95% CI: 84-94%) and negative aortic pulse pressure responses with 57% sensitivity (95% CI: 44-69%) and 96% specificity (95% CI: 91-98%). The magnitude of FPPG changes were strongly correlated with positive aortic pulse pressure changes (R(2) = 0.73, P < .0001) but less well correlated with negative aortic pulse pressure changes (R(2) = 0.43, P < .0001). FPPG selected 78% of the patients having positive aortic pulse pressure changes to CRT and identified the AV delay giving maximum aortic pulse pressure change in all selected patients. CONCLUSIONS: FPPG can provide a simple noninvasive method for identifying significant changes in aortic pulse pressure with high specificity, including identifying patients in whom aortic pulse pressure increases with CRT and the AV delay giving the maximum aortic pulse pressure.