Local effects of atherosclerotic plaque on arterial distensibility

Hypertension, diabetes, and hypercholesterolemia are characterized by a red uction in arterial distensibility and by accelerated atherosclerosis. Wheth er arterial stiffening is an inherent feature of these conditions or just t he consequence of the atherosclerotic clinical or subclinical lesions is no t known, however. Our aim was to obtain information on this issue by direct ly measuring, in humans, arterial distensibility both at the site of an ath erosclerotic lesion and at the proximal normal site. In 10 patients (8 men; mean +/- SEM age, 65.2 +/-3.4 years) affected by monolateral hemodynamic s ignificant internal carotid artery stenosis, we measured arterial distensib ility (Wall Track System; PIE Medical) bilaterally, both at the internal ca rotid artery and at the common carotid artery level. In the common carotid artery, measurements were made 3 cm below the bifurcation. In the affected internal carotid artery, measurements were made at the plaque shoulder (wal l thickness of 2 mm). Measurements were made in the contralateral internal carotid artery at a symmetrical level. Arterial wall thickness was measured in the same site of arterial distensibility. Arterial distensibility was l ess in the internal than in the common carotid artery, with a marked reduct ion at the plaque internal carotid artery level compared with the correspon ding contralateral site (-45%, P <0.01). It was also less, however, in the common carotid artery branching into the atherosclerotic internal carotid a rtery than in the contralateral common carotid artery (-25%, P <0.05). Wall thickness was similar in the 2 common carotid arteries and obviously great er in the affected internal carotid artery than in the contralateral artery . Arterial distensibility was markedly less in the internal carotid artery where there was a plaque compared with the intact contralateral internal ca rotid artery; it was also less, however, in the common carotid artery of th e affected side in comparison with the contralateral common carotid artery. This provides evidence that the effect of a plaque on arterial mechanical properties is not limited to the actual plaque site but rather extends to a considerable degree in a proximal direction.