| Popis: |
Ten patients, refractory to antihypertensive treatment with diuretics, β-adrenergic blocking drugs and hydralazine, were investigated. They had previously shown increased total peripheral resistance as well as increased blood flow resistance at rest and at maximal vasodilatation in a local vascular bed (calf), compared to hypertensive patients responding adequately to the same triple drug treatment. The results showed no differences between the groups in vascular smooth muscle tone at rest or in plasma volume. It was concluded that the inadequate response to therapy was mainly caused by a vascular abnormality interpreted as structural adaptive changes of the arteriolar vessel wall, more pronounced in the patients refractory to treatment. The patients were then treated with minoxidil (15–35 mg/day) as the only vasodilating agent, the dose of the β-adrenergic blocking agent and the diuretic therapy being kept almost constant. Plasma volume (Evans Blue) measurements and peripheral hemodynamic investigations were made during the previous regimen and when an acceptable BP reduction had been achieved on the combined treatment with minoxidil. Peripheral hemodynamic experiments on the calf blood flow were made with venous occlusion plethysmography at rest (resting flow and resistance) and after arterial occlusion and muslce work (maximal flow and resistance at maximal dilatation). BP was recorded simultaneously with the flow determinations indirectly in the right arm. After the change to minoxidil all patients displayed a reduction of arterial BP and reached adequate levels within two months. This BP reduction correlated positively to an increase in resting blood flow and was associated with decreased peripheral resistance at rest. A tendency towards increased plasma volume was demonstrated. No change was found in the resistance at maximal dilatation. Consequently, no sign of reversibility of the vascular abnormality was demonstrated after 1–2 months of BP-lowering therapy. |
