Myocardial disease in small animals

Animal models of heart failure: what is new?

Heart failure is the major cause of mortality in Western countries. Medical treatment of heart failure is associated with 50% survival at 5 years. Experimental models are required to better understand the progression of the disease and elaborate new therapy. Heart transplantation, left ventricular assist devices, artificial hearts, and cardiac bioassist techniques require animal models for testing and optimizing before they are implemented on human patients. The perfect model of heart failure that reproduces every aspect of the natural disease does not exist. Acute and chronic heart failure models have been developed to reproduce different aspect of the pathology.

[Cardiac arrhythmias induced by short-time maximal dynamic exercise (sprint): a study in greyhounds]

INTRODUCTION AND OBJECTIVES

Physical exercise causes a significant increase in the incidence of cardiac arrhythmias in athletes, basically when maximal capacity is approached and during the period of early recovery. In this study the incidence of cardiac arrhythmias consecutive to maximal exercise (sprint) was studied using racing greyhounds as a biomodel.

METHODS

The study was done on 399 greyhounds taking part in programmed speed races at a greyhound track. For each animals two electrocardiograms where taken: the first before the race and the second between 90 and 150 seconds after finishing it.

RESULTS

112 cases of abnormal arrhythmias were found, 32 before racing, and 80 afterwards. Of these 80 post-effort cases, 80% did not present any abnormalities in cardiac rhythm before racing. Only cases of electrical alternans, electrical alternans + sinus tachycardia, ventricular extrasystoles, sinus tachycardia and ventricular tachycardia were due to non-random phenomena.

CONCLUSIONS

Maximal physical exercise (sprint) provokes a significant increase (150%) in the incidence of abnormal cardiac arrhythmias during the period of early recovery: mainly electrical alternans, ventricular extrasystoles, sinus tachycardia and ventricular tachycardia. The class, sex, age, weight of greyhound and distance covered do not have a significant influence on the presentation of arrhythmias, except in cases of sinus tachycardia and distance.