Primary hypertension refractory to triple drug treatment: a study on central and peripheral hemodynamics.

Cardiac output, plasma volume and regional hemodynamic factors involved in blood pressure regulation were investigated in hypertensive patients refractory to the combined treatment with diuretics, propranolol and hydralazine. The patients were compared to hypertensive patients, matched for sex, age, weight, glomerular filtration rate and initial untreated blood pressure, responding adequately to the corre- sponding therapy. Cardiac output was determined with the dye-dilution technique (indocyanine green) and plasma volume with Evans Blue. Blood flow and vascular resistance at rest and at maximal vasodilatation in a skin (hand) and a muscle (calf) vascular bed were determined using venous occlusion plethysmography and intra-arterial and auscultatory blood pressure recordings, respectively. Maximal vasodilatation was obtained by direct and indirect heating, arterial occlusion and hand muscle work (hand), or by arterial occlusion and muscle work (calf).