ECHOCARDIOGRAPHIC ASSESSMENT OF LEFT VENTRICULAR HYPERTROPHY AND FUNCTION IN RENAL HYPERTENSIVE DOGS

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To investigate the performance of the hypertrophied left ventricle, M-mode echocardiographic measurements were performed 2 to 3 times weekly on 8 unanesthetized dogs for several weeks before and for 6 months after the induction of perinephritic hypertension. Four dogs with sham-wrapping and contralateral nephrectomy served as the controls. From a baseline value of 7.7 ± 0.4 mm (mean ± SD), left ventricular wall thickness increased to 9.0 ± 0.6 mm (p < 0.001) by the 4th week after the induction of hypertension and reached a plateau of 10.2 ± 1.2 mm (p < 0.001) by week 10. Fractional shortening of left ventricular dimension (%ΔD) increased during early left ventricular hypertrophy and remained elevated for 6 months in the surviving 6 hypertensive dogs. In hypertensive dogs, left ventricular concentric hypertrophy became detectable by week 6 of hypertension. Control dogs did not show these changes. At autopsy, the left ventricular weight of hypertensive and normotensive control dogs was 6.2 ± 1.4 g/kg and 4.3 0.5 g/kg (p < 0.05). In summary, during the early stage of left ventricular hypertrophy in renal hypertensive dogs cardiac performance increased. There is no evidence for deterioration of left ventricular performance as concentric left ventricular hypertrophy develops and becomes chronic.