[Heart muscle after heart infarct. Function of surviving heart muscle following acute myocardial infarct].
In the initial phase of the infarction, there is a decrease of ventricular function due to loss of contractile activity. In addition, a negative effect of the paradoxical movement of the infarcted area on the hemodynamics of the ventricle is noted. The stiffening of the infarcted area in the early stage has a favorable influence on ventricular function, leading to a change in the elastic properties of the ventricle. The loss of ventricular compliance persists after the infarction, and its severity depends on the extent of myocardial destruction. In the non-compliant ventricle, the end-diastolic pressure rises without a proportionate increase in volume. Consequently, the ventricular function curve shows a shift downward and to the right, making it difficult to distinguish between the loss of contractile function or compliance in the heart in situ. Evaluation of the contractile properties of the surviving cardiac muscle in situ is, however, hardly possible due to the changed geometry and the additonal elastic elements functioning in series with the surviving muscle. To exclude these factors, a study of the contractile properties of the surviving cardiac muscle in the isolated state was carried out following experimental myocardial infarction in cats. By ligating several coronary branches, infarctions in the area of the left ventricle were caused; to avoid the ischaemic border zone of the infarction, right ventricular papillary muscles were studied. Haemodynamic investigations showed an increase in right ventricular end-diastolic pressure which persisted 6 weeks after infarction. As early as 48 hours but, more significantly 1 week after infarction, there was a decrease of actively developed force in the surviving cardiac muscle due to a lower rate of force development. The resting length tension curve of the surviving cardiac muscle after infarction showed no alterations; and 6 weeks following infarction, almost normal contractility parameters were observed. As a result of the infarction, a decrease in contractility in the surviving cardiac muscle is observed during the early stage, which regresses after complete recuperation.
D000208:Acute Disease; D002302:Cardiac Output; D006321:Heart / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000503:physiopathology*; D009206:Myocardium / Q000378:metabolism; D013997:Time Factors
Der Herzmuskel nach Herzinfarkt. Die Funktion des überlebenden Herzmuskels nach akutem Myokardinfarkt