Blood pressure and left ventricular dysfunction in the spontaneously hypertensive rat.

The important role of the heart in the manifestation of systemic hypertension often becomes apparent with the development of left ventricular dysfunction. After a prolonged course of stable compensated left ventricular hypertrophy, spontaneously hypertensive rats (SHR) developed left ventricular dysfunction. A phase of overt left ventricular dysfunction and dilatation was present at an advanced age (24 months) in female SHR, a phase during which systemic hypertension was no longer manifest despite the maintenance of an increased vascular resistance. Similarly, when left ventricular dysfunction was induced after the experimental production of a myocardial infarction, the systemic arterial pressure levels of young SHR fell. This reduction in blood pressure was directly related to the extent of the histologic damage to the left ventricle. These studies underscore the important permissive role of the heart in the expression and maintenance of systemic hypertension.