Coronary blood flow and myocardial ischaemia in hypertension

The aim of this investigation was to study the coronary pressure-flow relationship in 60 patients with chronic arterial hypertension of diverse aetiologies and in 14 normotensive subjects (control group). The hypertensive cohort included 6 patients with isolated systolic hypertension (ISH), 7 renovascular hypertensive patients with abnormally elevated angiotensin II plasma levels but without electrocardiographic and/or echocardiographic evidence of left ventricular hypertrophy (LVH) and 47 subjects with essential hypertension (EH), 21 of whom had LVH by electrocardiogram and/or echocardiogram. In the hypertensive cohort a Frank-Starling-like curve was found to describe the coronary pressure-flow relationship when the baseline values for coronary sinus blood flow (CBF, intravascular Doppler technique) were plotted against mean aortic pressure (intra-arterial blood pressure). In particular, the descending limb of such a curve represented a critical region where CBF was "inappropriately" low with respect to perfusion pressure. It was thus concluded that this inability of the heart to adapt CBF to its needs might account for the higher propensity to develop myocardial ischaemia encountered in severe essential hypertensive subjects with concomitant LVH and renovascular hypertensive patients.