Left Ventricular Endocardial Pacing Improves Resynchronization Therapy in Canine Left Bundle-Branch Hearts

Abstract

Background-We investigated the benefits of the more physiological activation achieved by left ventricular (LV) endocardial pacing (ENDO) as compared with conventional epicardial (EPI) LV pacing in cardiac resynchronization therapy. Methods and Results-In 8 anesthetized dogs with experimental left bundle-branch block, pacing leads were positioned in the right atrium, right ventricle, and at 8 paired (EPI and ENDO) LV sites. Systolic LV pump function was assessed as LVdP/dtmax and stroke work and diastolic function as LVdP/dtmin. Electrical activation and dispersion of repolarization were determined from 122 epicardial and endocardial electrodes and from analysis of the surface ECG. Overall, ENDO-biventricular (BiV) pacing more than doubled the degree of electrical resynchronization and increased the benefit on LVdP/dtmax and stroke work by 90% and 50%, respectively, as compared with EPI-BiV pacing. During single-site LV pacing, the range of AV intervals with a Ͼ10% increase in LV resynchronization (79Ϯ31 versus 32Ϯ24 ms, PϽ0.05) and LVdP/dtmax (92Ϯ29 versus 63Ϯ39 ms) was significantly longer for ENDO than for EPI pacing. EPI-BiV but not ENDO-BiV pacing created a significant (40Ϯ21 ms) transmural dispersion of repolarization. Conclusions-Data

Long‐Term Outcomes of Cardiac Resynchronization Therapy Using Apical Versus Nonapical Left Ventricular Pacing

“…Our finding of lower cardiac mortality as well as death from pump failure with an apical LV lead position is in keeping with experimental and clinical studies showing that LV apical pacing is physiologically superior to nonapical pacing 4, 5…”

“…Similar findings emerged from a subanalysis of the REVERSE (Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction) trial 3. These findings are counterintuitive, as previous experimental and clinical evidence shows that an apical LV lead position is more favorable than nonapical positions 4, 5. During normal sinus rhythm in intact myocardium, electrical impulses travel through the rapid conduction system from the His bundle toward the low apex.…”

“…Computer modeling studies support the notion that LV lead positioning should be guided by what is most physiologically close to normal activation rather than targeting the latest activated region 7. In this regard, van Deursen et al used a canine left bundle‐branch block (LBBB) model to show that the highest hemodynamic response during CRT, measured using the rate of rise of LV pressure (LV dP/dt), occurred with LV apical positions rather than with basal and midventricular positions 4. Other pacing studies have shown similar findings 5.…”

Left Ventricular Endocardial Pacing Techniques as an Alternative for Ineffective Cardiac Resynchronization Therapy and the Role of Acute Hemodynamic Evaluation

“…Epicardial stimulation from the CS position resulted in an increase in LVdP/ dt of +7.1%±2.5%, whereas from the endocardial counterpart an increase of 6.7%±4.1% was measured, an observation which is in contrast with other studies Van Deursen at al., 2007;Van Deursen et al, 2008). In all nonresponders the increase in LVdP/ dt by CS pacing was below 10%.…”

Cardiac Resynchronization Therapy: Lead Positioning and Technical Advances

“…Van Deursen demonstrated in an acute canine model a superior electrical resynchronization as well as +dP/dT(max) when endocardial biventricular stimulation was used instead of epicardial stimulation. In addition, whereas epicardial stimulation resulted in a transmural dispersion of repolarization, this was not observed in endocardial stimulation (van Deursen et al, 2009). However, Spragg et al compared the hemodynamic effects of endocardial pacing at sites directly transmural to the CS lead tip in a small study of patients and found no difference in hemodynamics (Spragg et al, 2010).…”