Key result
Induction of pressure-overload left ventricular hypertrophy resulted in depressed myocardial function in adult sheep compared with controls, whereas lambs maintained normal function.
Why the study?
Does the age at which pressure-overload left ventricular hypertrophy is induced affect systolic myocardial function in an ovine model?
Does the age at which pressure-overload left ventricular hypertrophy is induced affect systolic myocardial function in an ovine model?
In an ovine model, maturation decreases the ability of the myocardium to maintain normal contractility in the presence of pressure-overload hypertrophy.
Age at LVH induction may alter systolic function in ovine models; leaves open translation to human pressure-overload cardiomyopathy.
The effect of pressure-overload left ventricular hypertrophy (LVH) on myocardial function is controversial. A major factor in the controversy may be the age at which the pressure overload was induced. The goal of this study was to determine whether the age at which the LVH was induced affected systolic myocardial function. We studied lambs (n = 8) and sheep (n = 7) with LVH induced by constricting the ascending aorta and their sham-operated controls (n = 7 and n = 7). This new, unsedated, ovine model of LVH was large enough to accommodate chronic surgical implantation of instrumentation and the induction of pressure-overload hypertrophy in both young and adult age groups. Solid-state intraventricular pressure transducers and sonomicrometer crystal were used to assess instantaneous left ventricular pressure and dimensions. Myocardial contractility was assessed with midwall shortening at common preload and afterload. Load alterations were induced by graded infusion of methoxamine. There was depressed myocardial function in adult sheep with LVH compared with adult controls. Lambs with and without LVH had normal left ventricular myocardial function, similar to adult controls. Similar results were obtained in studies after beta-adrenergic receptor blockade. We conclude that maturation decreases the ability of the myocardium to maintain normal contractility in the presence of pressure-overload hypertrophy.
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Aoyagi et al. (1992) studied Pressure-overload left ventricular hypertrophy (n=29). Ascending aorta constriction to induce pressure-overload left ventricular hypertrophy vs. Sham operation was evaluated on Systolic myocardial function (myocardial contractility assessed with midwall shortening). Induction of pressure-overload left ventricular hypertrophy resulted in depressed myocardial function in adult sheep compared with controls, whereas lambs maintained normal function.
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