Abstract
BackgroundHeart failure with preserved left ventricular ejection fraction and abnormal diastolic function is commonly observed after recovery from an acute myocardial infarction. The aim of this study was to investigate the physiopathology of heart failure with preserved ejection fraction in a model of healed myocardial infarction in dogs.MethodsEchocardiography, levels of neurohormones and conductance catheter measurements of left ventricular pressure-volume relationships were obtained in 17 beagle dogs 2 months after a coronary artery ligation, and in 6 controls.ResultsHealed myocardial infarction was associated with preserved echocardiographic left ventricular ejection fraction (0.57 ± 0.01, mean ± SEM) and altered Doppler mitral indices of diastolic function. NT-proBNP was increased, aldosterone was decreased, and norepinephrine was unchanged. Invasive measurements showed a markedly decreased end-systolic elastance (2.1 ± 0.2 vs 6.1 ± 0.8, mmHg/ml, p < 0.001) and end-systolic elastance to effective arterial elastance ratio (0.6 ± 0.1 vs 1.4 ± 0.2, p < 0.001), with altered active relaxation (dP/dtmin -1992 ± 71 vs -2821 ± 305, mmHg/s, p < 0.01) but preserved left ventricular capacitance (70 ± 6 vs 61 ± 3, ml at 20 mmHg, p = NS) and stiffness constant. Among echocardiographic variables, the wall motion score index was the most reliable indicator of cardiac contractility while E', E/A and E'/A' were correlated to dP/dtmin.ConclusionsIn the canine model of healed myocardial infarction induced by coronary ligation, heart failure is essentially characterized by an altered contractility with left ventricular-arterial uncoupling despite vascular compensation rather than by abnormal diastolic function
Highlights
Heart failure with preserved left ventricular ejection fraction and abnormal diastolic function is commonly observed after recovery from an acute myocardial infarction
In order to explain the pathophysiological mechanism of elevated diastolic pressures, we investigated systolic and diastolic function by invasive studies of left ventricular (LV) pressure-volume relationships in dogs, two months after recovery from myocardial infarction induced by a coronary ligation
Magnetic resonance imaging The magnetic resonance imaging (MRI) performed 2 months after myocardial infarction revealed that we were in presence of a moderate lateroposterior infarct with a myocardial infarction size of 13 ± 0.74% of the LV wall
Summary
Heart failure with preserved left ventricular ejection fraction and abnormal diastolic function is commonly observed after recovery from an acute myocardial infarction. Heart failure with preserved left ventricular (LV) systolic function as assessed by echocardiographic measurement of an ejection fraction (EF) higher than 50%, together with altered indices of diastolic function [1], is observed after acute myocardial infarction in 30 to 50% of heart failure patients [2,3]. In order to explain the pathophysiological mechanism (diastolic versus systolic heart failure) of elevated diastolic pressures, we investigated systolic and diastolic function by invasive studies of LV pressure-volume relationships in dogs, two months after recovery from myocardial infarction induced by a coronary ligation. We recorded indices of systolic and diastolic function by Doppler echocardiography and tissue Doppler imaging, and measured circulating neurohormones N-terminal Btype natriuretic propeptide (NT-proBNP), aldosterone and norepinephrine, to investigate their potential value in predicting systolic and diastolic alterations in LV function
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