1. Blood flow resistance was studied in two peripheral vascular beds in 15 patients with previous malignant hypertension and in a matched group of patients with treated ‘benign’ hypertension and in matched control subjects. Studies were made during rest and after the induction of maximal vasodilatation.
2. In the hand (representing mainly a skin vessel bed), both hypertensive groups had significantly higher resistance at maximal dilatation than the normotensive group (2.5 and 2.5 units respectively as compared with 1.9 units, P < 0.01).
3. In the calf muscle vascular bed the patients with previous malignant hypertension had the most severe changes. Resistance at maximal dilatation was 2.4 units as compared with 1.9 units in the group with ‘benign’ hypertension (P < 0.05) and 1.6 units in the control group (P < 0.001 and P < 0.05 respectively).
4. These findings indicate structural changes in the resistance vessels of both hypertensive groups, which means that, in spite of substantial long-term lowering of blood pressure, arteriolar vascular changes remain. Accordingly, these changes may not be entirely reversible. The degree of reversibility also appears to be different in the two vascular beds studied.
