The Intervention Research Of Ivabradine On Cardiac Function And Ventricular Arrhythmia In Heart Failure Canine Model

Objectives: The aim of this study was to explore the influence of ivabradine on cardiac function and ventricular arrhythmia in heart failure canine model.Methods: 12 beagles were randomly divided into normal control group, heart failure under ivabradine intervention group, heart failure of no drug intervention group. Heart failure was builded by rapid pacing right ventricular for 4 weeks.then formated the chronic heart failure model.The heart failure of drug intervention group gave ivabradine to intervene at the same time of pacing.The controlled group was sham-operation group, did not implanted pacemaker.All the beagles used ultrasonic to detect the cardiac function before operation and after four weeks of rapid pacing.Used S1S1=120 ms(500 BPM) as stimulate perimeter, repeated stimulation 10 times in right ventricular, record three groups beagle the inducing rate of ventricular tachycardia.Then also used S1S1=110 ms as stimulate perimeter to stimulate right ventricular,The voltage start with 1v. Then increases gradually,each time increased by 0.2 mv.Finally used the minimum voltage which caused ventricular fibrillation as ventricular fibrillation threshold, record each group the ventricular fibrillation threshold.Results: compared with control group and the group before rapid pacing,after 4 weeks rapid pacing, beagles appeared a corresponding clinical manifestations of chronic heart failure;Ultrasonic echocardiography showed the heart cavity diameter is larger; left ventricular ejection fraction decreases obviously, the difference showed statistical significance(P<0.05).Compared with under no drug intervention group,the heart failure under ivabradine intervention group’s left ventricular end-diastolic diameter, end systolic diameter was smaller, ejection fraction was higher,the difference showed statistical significance(P<0.05).Compared with under no drug intervention group, the inducing rate of ventricular tachycardia in ivabradine intervention group was lower, the difference showed statistical significance(P<0.05).But there was noobvious difference with the control group(P>0.05).Ventricular fibrillation threshold determination: ventricular fibrillation threshold in contrast group was 9.1 ±0.6 V, the average of ventricular fibrillation threshold in heart failure group was 4.9 ±0.7V, the heart failure under ivabradine intervention group’s average ventricular fibrillation threshold was6.4±0.5V.Compared with the heart failure group, the ventricular fibrillation threshold of ivabradine intervention group was obviously higher, the difference showed statistical significance(P<0.05).compared with control group, the ventricular fibrillation threshold of ivabradine intervention group was lower, the difference showed statistical significance(P<0.05).Conclusion: Rapid pacing right ventricular to build the animal model of chronic heart failure is feasible.Ivabradine can improve cardiac function of heart failure canine,reduce the incidence of ventricular arrhythmia after heart failure, can improve the ventricular fibrillation threshold.