Collateral compensation of severe carotid stenosis.

In 516 patients who had endarterectomies for unilateral severe carotid stenoses, arteriography demonstrated no contralateral severe stenoses or occlusions. Pre and postoperative ocular pneumoplethysmography (OPG-Gee) measured simultaneous bilateral ophthalmic systolic pressures (OSP). Immediately after each OPG test a brachial systolic pressure (BSP) was measured with a stethoscope, cuff and manometer. Bilateral ophthalmobrachial systolic pressure (OBSP) indices were calculated from the three pressures measured with the combined testing. Analysis of these OBSP data indicates that the severe stenoses were relatively well compensated in 314 of the 516 patients (61%) whereas there was limited collateral compensation in the remaining 202 patients (39%). The data also suggest that the latter group incurs a greater element of compensatory central hypertension, which is reversed by carotid endarterectomy.