INTRODUCTION: The aim of this study was to evaluate epicardial biventricular pacing as a means of maintaining synchronous ventricular activation in an acute @entity235 model of @entity713 with normal ventricular anatomy and function. Chronic single-site ventricular pacing results in dyssynchronous ventricular activation and may contribute to @entity67 . Biventricular pacing has been used successfully in adult @entity1 with @entity712 . METHODS AND RESULTS: This was an acute study of open chest mongrel @entity235 (n = 13). ECG, left ventricular (LV), aortic, and pulmonary arterial pressures were measured. LV impedance catheters were used to assess cardiodynamics using instantaneous LV @entity551 ( @entity551 ). Following radiofrequency ablation of the AV node, a temporary pacemaker was programmed 10 beats/min above the intrinsic atrial rate, with an AV interval similar to the baseline intrinsic PR interval. The pacing protocol consisted of 5-minute intervals with the following lead configurations: right atrium-right ventricular apex (RA-RVA), RA-LV apex (LVA), and RA-biventricular using combinations of four ventricular sites (RVA, RV outflow tract [RVOT], LVA, LV base [LVB]). RA-RVA was used as the experimental control. LV systolic mechanics, as measured by the slope of the end-systolic (Ees) @entity551 (ESPVR, mmHg/cc), was statistically greater (P < 0.05) with all modes of biventricular pacing (RA-RVA/LVA 20.0 +/- 2.9, RA-RVA/LVB 18.4 +/- 2.9, RA-RVOT/LVA 15.1 +/- 1.8, RA-RVOT/LVB 17.6 +/- 2.9) compared to single-site ventricular pacing (RA-RVA 12.8 +/- 1.6). Concurrent with this improvement in myocardial performance was a shortening of the QRS duration (RA-RVA 97.7 +/- 2.9 vs RA-RVA/LVA 75.7 +/- 4.9, RA-RVA/LVB 70.3 +/- 4.9, RA-RVOT/LVA 65.3 +/- 4.4, and RA-RVOT/LVB 76.7 +/- 5.9, P < 0.05). CONCLUSION: In this acute @entity235 model of @entity713 , QRS duration shortened and LV performance improved with epicardial biventricular pacing compared to standard single-site ventricular pacing.

Evaluation of myocardial performance with conventional single-site ventricular pacing and biventricular pacing in a @entity235 model of XXXX .

@entity1 :: ('9606', 'Species') :: ['patients'] @entity712 :: ('MESH:D006333', 'Disease') :: ['congestive heart failure'] @entity235 :: ('9615', 'Species') :: ['canine', 'dogs'] @entity713 :: ('MESH:D054537', 'Disease') :: ['AV block'] @entity67 :: ('MESH:D018754', 'Disease') :: ['ventricular dysfunction'] @entity551 :: ('MESH:D007022', 'Disease') :: ['PVR', 'pressure-volume relations']
@entity713 :: (MESH:D054537,Disease) :: ['atrioventricular block']
