Acute haemodynamic effects of increase in paced heart rate in heart failure patients recorded with an implantable haemodynamic monitor.

AIMS: The aim of this study was to investigate the acute effects of different biventricularly paced heart rates (pHRs) on right ventricular (RV) haemodynamics in heart failure (HF) patients with an implantable haemodynamic monitor (IHM). METHODS AND
RESULTS: At rest, seven pHRs, range 60-120 bpm (steps of 10), were randomly programmed and maintained for 60 s in 10 patients (male, 65±12 years, New York Heart Association II-III). Right ventricular systolic (RVSP) and diastolic pressures, estimated pulmonary artery diastolic (ePAD) pressure, and RV+dP/dt were recorded beat-to-beat using the IHM. Cardiac output (CO) was estimated from the RV pressure waveforms and arterial blood pressure was measured (Portapres®). To compare the haemodynamic effects of increased pHR at rest to that of spontaneous, sinus-driven heart rate (HR) increase, patients also performed a symptom-limited bicycle exercise. At rest, RV+dP/dt increased significantly with elevated pHR (P, main effect, <0.001), whereas filling pressures (ePAD and RVSP) decreased significantly in the range 60-100 bpm (P<0.03 and P<0.003, respectively) but tended to increase or level out at pHRs>00 bpm. At a pHR of 100 bpm, ePAD was 1.4 mmHg lower compared with 60 bpm (P<0.01). Cardiac output increased gradually with elevated pHR at rest (P<0.001). Both total peripheral and estimated pulmonary arterial resistance significantly decreased with increased pHR. During exercise-induced maximum HR increase, RV+dP/dt, ePAD, and CO were all significantly higher compared with the corresponding pHR at rest.
CONCLUSION: During cardiac resynchronization therapy in HF patients, the force frequency relationship is present in the RV, as increasing the pHR in the range 60-100 bpm results in decreased filling pressures and increased CO.