Study Of Cardiac Remodeling Produced By Rapid Right Ventricular Pacing In The Dog

Objectives This study sought to determine whether electrical and machine remodeling of ventricle has effected on advanced heart failure by chronic rapid right ventricular pacing at 230±10 beats per minute for 3 weeks in a canine pacing - induced congestive heart failure model.Methods Ten dogs were divided into 2 groups, namely control group and CHF group: Pacing group (PC , n = 5) :pacing rate 230±10 beats per minute;: Sham operation control (SO , n = 5). The control group received sham operation , while the CHF group received rapid right ventricular pacing at the rate of 230±10 beats per minute with the duration of 3 weeks. Clinical symptoms and hemodynamic parameters were used to evaluate the severity of heart failure.: Haemodynamic parameters were detected via M-mode echocardiograms parameters. Heart morphology change was observed by Scanning Electron Microscopy , Light Microscopic Examination.and Naked eye. In the mean time I measured ventricular monophasic action potential duration(MAPD), MAPD90 and MAPD50 in Rapid ventricular pacing dog or sham operation control.dog. Resuts All dogs had clinical conditions of CHF after rapid right ventricular pacing for3 weeks. It showed variant symptoms and the hemodynamic parameters implied that the severity of heart failure increased progressively. Two-dimensional short-axis echocardiograms were obtained at the level of the head of the papillary muscle.LV end-diastolic and LV end-systolic diameters were each larger, but Ejection Fraction was smaller in Pacing- dogs than in Sham operation control dogs. Electron mircroscope and Light Microscope of ventricular myocytes from pacing show disorganized structure.