Electrocardiographic alterations suggestive of myocardial injury elicited by rapid pressure lowering in hypertension.

In hypertensive cardiac hypertrophy, the elevated coronary perfusion pressure compensates importantly for the raised coronary resistance. An imbalance between perfusion and left ventricular (LV) mass, such as that occurring with rapid or excessive blood pressure lowering, may result in an inadequate oxygen supply. In 28 primary hypertensives (Group A) with LV mass index within the mean + 1 SD (96 + 19 g m-2) of 145 controls, and in 26 patients whose LV mass exceeded these values (Group B), we lowered the diastolic blood pressure rapidly to 85-90 mmHg, using both s.l. nifedipine and i.v. nitroprusside. During each test, eight patients in Group B had inversion of T waves in lead I, aVL, V3-V6, which waxed and waned in parallel with the pressure fall and recovery, and was independent of conduction disturbances, variations or group differences in the QRS axis, QTc interval, heart rate, LV fractional shortening and wall stress. A 'coronary steal phenomenon' or passive collapse in compliant lesions consequent to vasodilatation may trigger acute myocardial ischaemia in the presence of severe coronary disease. Patients developing the ECG alterations, however, were free from angina and four, who were subjected to coronary angiography, had normal arteriograms. Patients with the myocardial injury pattern showed greater LV mass indices and larger falls in diastolic pressure for it to reach normal levels. The supply of energy to the hypertrophied hypertensive heart seems to depend importantly on the coronary perfusion pressure, suggesting the cautious use of rapid acting drugs.