Objective:The aim was to assess the effect of nisoldipine on left ventricular systolic and diastolic function during prolonged myocardial ischaemia. Methods: The left circumflex coronary artery was ligated for 2 h and reperfused for 4 h in 12 calves. The animals were randomised to a control group (n=6) or to treatment with 1.25 mg.h-' intravenous nisoldipine (n=6) during 2 h of ischaemia. Circulatory support by a ventricular assist device was performed throughout the experiment except for the time of haemodynamic measurements. Regional wall thickening of a normal and an ischaemic left ventricular region was determined using pairs of ultrasonic crystals. Left ventricular pressure was measured by micromanometry. Left ventricular wall thickness and regional wall stiffness at a common preload of 10 mm Hg were calculated using an elastic model with shifting asymptote. Results: Ten animals survived after 6 h. No difference was observed in systolic function between controls and nisoldipine treated animals. Systolic thickening of the ischaemic wall remained depressed 4 h after reperfusion and showed some recovery after dopamine infusion. Ischaemic wall stiffness at a common preload was lower after nisoldipine during ischaemia and reperfusion than in controls. Control wall stiffness remained unchanged during the whole experiment with and without nisoldipine. Diastolic thinning of the ischaemic wall was prevented by nisoldipine during ischaemia and after reperfusion. Conclusions: Prolonged myocardial ischaemia is associated with increased myocardial stiffness of the ischaemic wall. Mechanical unloading can help to bridge the acute phase but cannot prevent postischaemic diastolic dysfunction of the ischaemic wall. Nisoldipine has a beneficial effect on regional diastolic function during ischaemia and reperfusion by decreasing regional wall stiffness and preventing diastolic thinning of the ischaemic wall. Ccirclinvciscular Research 1993;27:53 1-536 rolonged myocardial ischaemia is associated with regional myocardial dysfunction which can persist for P hours and days and may lead to irreversible myocardial damage. Diastolic dysfunction has been reported in the experimental animal during acute ischaemia" as well as during postreperfusion myocardial stunning.' ' Administration of calcium antagonists beneficially influences diastolic dysfunction after short term ischaemia.h However, long term ischaemia has not yet been studied with regard to diastolic dysfunction and its reversibility with calcium antagonists. Long term ischaemia is often associated with variable myocardial damage and may be accompanied by severe arrhythmias and low output failure.'-" It has been shown previously that systolic function can be preserved during long term myocardial ischaemia by extracorporeal circulatory However, the effect of prolonged ischaemia on regional diastolic dysfunction was not evaluated. Thus the purpose of the present study was ( 1 ) to assess the effect of long term myocardial ischaemia on regional diastolic dysfunction and ( 2 ) to...
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