Isosorbide dinitrate and pulsatile arterial haemodynamic variables in hypertension

The effect of a sustained-release oral isosorbide dinitrate (ISDN) preparation on cerebral and forearm circulation was determined in 16 patients with mild to moderate essential hypertension. Measurements were made by pulsed Doppler velocimetry in the common carotid and the brachial arteries. Pulse wave velocity of the forearm was simultaneously recorded by means of strain gauge arterial mechanography allowing non-invasive evaluation of compliance and characteristic impedance of the brachial artery. Four hours after ISDN ingestion, the patients exhibited a significant decrease in blood pressure without a change in heart rate. An increase in carotid and brachial artery diameter was shown whereas blood flow increased only in the forearm. Resistance decreased significantly in both carotid and brachial vascular beds but only in the brachial vascular bed was the baseline resistance directly correlated with the change in brachial bed resistance. Concerning pulsatile large artery parameters, pulse wave velocity and characteristic impedance diminished, and brachial artery compliance increased significantly. The tangential tension of carotid and brachial arteries did not change. An increase in plasma renin activity was observed and related to the vasodilating effect on small arteries of the brachial vascular bed. This study showed that the antihypertensive effects of ISDN were accompanied by a strong vasodilatory action on small and large arteries and by an improvement in the pulsatile behaviour of large arteries.