Effects of amyl nitrite on left ventricular relaxation in patients with borderline hypertension.
The effects of systemic hypertension on left ventricular relaxation properties remain largely undefined. To assess such effects 22 normal volunteers and 15 patients with borderline hypertension were examined. The tangent to the echocardiographic left ventricular posterior wall endocardium was measured in diastole and was normalized for end-diastolic dimension to yield normalized velocity of relaxation. This velocity of relaxation was measured at rest and throughout inhalation of amyl nitrite. Mean value +/- standard deviation (SD) from rest to peak amyl nitrite effect for the normal group and for the patients with borderline hypertension was 3.3 +/- 0.6 leads to 7.2 +/- 1.1 and 3.0 +/- 0.8 leads to 4.4 +/- 1.1 s-1, respectively. All 22 persons in the normal group and 2 of the 15 patients with borderline hypertension attained normalized velocity of relaxation greater than 5.5 s-1 with administration of amyl nitrite. Multivariate analysis in the normal group identified heart rate, mean arterial pressure, and fractional shortening as the best predictors of normalized left ventricular relaxation velocity (r = 0.85; p less than 0.001). The increase in the normalized velocity of relaxation induced by amyl nitrite is blunted in patients with borderline hypertension. These changes in left ventricular relaxation identify early cardiac involvement and may prove clinically useful in hypertensive patients.