Espen Boe1,2,3, Otto A Smiseth1,2,3,4, Petter Storsten1,2,3, Oyvind S Andersen1,2,3,4, John Aalen1,2,3, Morten Eriksen1,2, Magnus R Krogh1, Erik Kongsgaard2,4, Espen W Remme1,2,4, Helge Skulstad1,2,3,4. 1. Institute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway. 2. Center for Cardiological Innovation, Oslo University Hospital, Rikshospitalet, Oslo, Norway. 3. Institute of Clinical Medicine, University of Oslo, Oslo, Norway. 4. Department of Cardiology, Oslo University Hospital, Rikshospitalet, 0027 Oslo, Norway.
Abstract
AIMS: There are conflicting data and no consensus on how to measure acute response to cardiac resynchronization therapy (CRT). This study investigates, which contractility indices are best markers of acute CRT response. METHODS AND RESULTS: In eight anaesthetized dogs with left bundle branch block, we measured left ventricular (LV) pressure by micromanometer and end-diastolic volume (EDV) and end-systolic volume (ESV) by sonomicrometry. Systolic function was measured as LV ejection fraction (EF), peak rate of LV pressure rise (LV dP/dtmax) and as a gold standard of contractility, LV end-systolic elastance (Ees), and volume axis intercept (V0) calculated from end-systolic pressure-volume relations (ESPVR). Responses to CRT were compared with inotropic stimulation by dobutamine. Both CRT and dobutamine caused reduction in ESV (P < 0.01) and increase in LV dP/dtmax (P < 0.05). Both interventions shifted the ESPVR upwards indicating increased contractility, but CRT which reduced V0 (P < 0.01), caused no change in Ees. Dobutamine markedly increased Ees, which is the typical response to inotropic stimulation. Preload (EDV) was decreased (P < 0.01) by CRT, and there was no change in EF. When adjusting for the reduction in preload, CRT increased EF (P = 0.02) and caused a more marked increase in LV dP/dtmax (P < 0.01). CONCLUSION: Increased contractility by CRT could not be identified by Ees, which is a widely used reference method for contractility. Furthermore, reduction in preload by CRT attenuated improvement in contractility indices such as EF and LV dP/dtmax. These results suggest that changes in LV volume may be more sensitive markers of acute CRT response than conventional contractility indices.
AIMS: There are conflicting data and no consensus on how to measure acute response to cardiac resynchronization therapy (CRT). This study investigates, which contractility indices are best markers of acute CRT response. METHODS AND RESULTS: In eight anaesthetized dogs with left bundle branch block, we measured left ventricular (LV) pressure by micromanometer and end-diastolic volume (EDV) and end-systolic volume (ESV) by sonomicrometry. Systolic function was measured as LV ejection fraction (EF), peak rate of LV pressure rise (LV dP/dtmax) and as a gold standard of contractility, LV end-systolic elastance (Ees), and volume axis intercept (V0) calculated from end-systolic pressure-volume relations (ESPVR). Responses to CRT were compared with inotropic stimulation by dobutamine. Both CRT and dobutamine caused reduction in ESV (P < 0.01) and increase in LV dP/dtmax (P < 0.05). Both interventions shifted the ESPVR upwards indicating increased contractility, but CRT which reduced V0 (P < 0.01), caused no change in Ees. Dobutamine markedly increased Ees, which is the typical response to inotropic stimulation. Preload (EDV) was decreased (P < 0.01) by CRT, and there was no change in EF. When adjusting for the reduction in preload, CRT increased EF (P = 0.02) and caused a more marked increase in LV dP/dtmax (P < 0.01). CONCLUSION: Increased contractility by CRT could not be identified by Ees, which is a widely used reference method for contractility. Furthermore, reduction in preload by CRT attenuated improvement in contractility indices such as EF and LV dP/dtmax. These results suggest that changes in LV volume may be more sensitive markers of acute CRT response than conventional contractility indices.
Authors: Manuel Villegas-Martinez; Magnus Reinsfelt Krogh; Øyvind S Andersen; Ole Jakob Sletten; Ali Wajdan; Hans Henrik Odland; Ole Jakob Elle; Espen W Remme Journal: Front Physiol Date: 2022-06-02 Impact factor: 4.755