Myocardial remodeling and bioelectric changes in tachycardia-induced heart failure in dogs

Abstract

In this study, electrical and structural remodeling of ventricles was examined in tachycardia-induced heart failure (HF). We studied two groups of weight-matched adult male mongrel dogs: a sham-operated control group (n=5) and a pacing group (n=5) that underwent ventricular pacing at 230 bpm for 3 weeks. Clinical symptoms of congestive HF were observed in both groups. Their hemodynamic parameters were determined and the severity of the HF was evaluated by M-mode echocardiography. Changes in heart morphology were observed by scanning electron and light microscopy. Ventricular action potential duration (APD), as well as the 50 and 90% APD were measured in both groups. All dogs exhibited clinical symptoms of congestive HF after rapid right ventricular pacing for 3 weeks. These data indicate that rapid, right ventricular pacing produces a useful experimental model of low-output HF in dogs, characterized by biventricular pump dysfunction, biventricular cardiac dilation, and non-ischemic impairment of left ventricular contractility. Electrical and structural myocardial remodeling play an essential role in congestive HF progression, and should thus be prevented.

Evaluation of Left Ventricular Diastolic Dysfunction with Early Systolic Dysfunction Using Two‐Dimensional Speckle Tracking Echocardiography in Canine Heart Failure Model

“…Our light microscopic examination of left ventricular myocytes showed disorganized cardiac muscle fibers, cellular necrosis and vacuolar degeneration after 2 weeks of RVP. Furthermore, electron microscopy revealed that significant changes were found in mitochondria, including markedly decreased matrix density, distinct mitochondrial swelling with significant disruption or disappearance of cristae, and vacuolar degeneration, which was in consistent with the study by Song et al…”