No abstract

Metabolic data obtained during sodium depletion (10-mEq Na, 90-mEq K diet plus thiazide) from 13 hypertensive patients (HT) with low plasma renin activity (PRA) were compared with data from 15 normotensive subjects and three patients with renovascular hypertension (RHT). With Na depletion plasma renin activity and urinary aldosterone excretion increased promptly in NT and RHT. In contrast, PRA in HT after 5 days of Na depletion was only one third that of the NT after 2 days of depletion, and aldosterone excretion did not change significantly. This depressed renin and aldosterone response in HT can be overcome by extending the depletion period and administering spironolactone. In HT, Na and loss of weight was significantly lower than in NT. HT Negroes retained more potassium than HT whites and four out of seven NT Negroes and none of eight NT white subjects had a positive K balance. The hypertension of patients with low PRA appears to be due to genetic or environmental factors or to both. Additional Indexing Words: Aldosterone excretion Sodium depletion Spironolactone THE DEVELOPMENT of methods for the assay of renin activity in human plasma has made it possible to separate from the hypertensive population an interesting group of patients with suppression of renin secretion. In 174 of our original group of 600 patients with hypertension,' renin could not be detected in the peripheral plasma. Although a great deal of interest was aroused by reports that suppression of renin activity occurs in hypertensive patients with primary aldosteronism,2 the prevalence of primary aldosteronism among hypertensive patients

A method was described for the quantitative determination of renin in small amounts of dialyzed human plasma, utilizing the first order reaction constant. A wide variation was found in the renin-substrate (angiotensinogen) content of plasma of patients with arterial hypertension. Many of these patients had high concentrations of this factor.

The utility of exercise echocardiography for the diagnosis of coronary artery disease has been demonstrated in populations consisting largely of men with a high prevalence of disease. To determine the diagnostic value of exercise echocardiography in women, 57 women who presented with chest pain were studied with coronary cineangiography and echocardiography combined with either treadmill (n = 38) or bicycle exercise (n = 19). Significant coronary artery disease (greater than or equal to 50% reduction in luminal diameter) was present in 28 (49%) of 57 patients, including 16 (84%) of 19 who had typical angina, and 12 (32%) of 38 who had atypical chest pain. The overall sensitivity and specificity of echocardiography were both 86%. Exercise echocardiography correctly determined the presence or absence of coronary artery disease in 32 (84%) of 38 patients who had atypical chest pain and in 17 (89%) of 19 who had typical angina (p = NS). The exercise electrocardiogram (ECG) was nondiagnostic in 17 patients (30%) who had rest ST segment depression or ST depression with exercise that could also be induced by hyperventilation or changes in position. The correct diagnosis was made by echocardiography in 14 (82%) of 17 patients with a nondiagnostic exercise ECG. In conclusion, exercise echocardiography has a clinically useful level of sensitivity and specificity for the detection of coronary artery disease in women. The technique provides diagnostic information in women presenting with atypical chest pain and in those who have a nondiagnostic exercise ECG.