Rat heart structural and functional characteristics and gas exchange parameters after experimental myocardial infarction

Rat heart structural and functional changes and gas exchange parameters were investigated in six months after experimental myocardial infarction. Left ventricular end-systolic and end-diastolic dimensions in rats with chronic heart failure were 78 and 30% higher than in control respectively. Left ventricle cavity volume in systole and diastole were 5 and 2 times increased respectively. Left ventricular cavity stretching was accompanied by thinning of the interventricular septum. Left ventricular structural changes leads to its functional deterioration. Left ventricular contraction fraction was reduced by 60%, and the ejection fraction--by 52% in comparison with control. Gas exchange investigation revealed that in six month after myocardial infarction oxygen consumption of operated rats was increased by 30% and production of carbon dioxide by more than 40%. Respiratory quotient, which reflects the nature of oxidized substrates, in rats with myocardial infarction was amounted to 0.85, indicating significant increase in the contribution of carbohydrates as an energy substrate for myocardial metabolism.