Chronic occlusive arterial disease of the extremities.

CHRONIC occlusive arterial diseases are the most common and the most disabling of all peripheral vascular disorders. Some of the causes of chronie arterial occlusion are arteriosclerosis obliterans, thromboangiitis obliterans (Buerger's disease), primary arterial thrombosis, which presumably results froni hypercoagulable blood, embolism, which is almost always associated with heart disease or peripheral arterial aneurysms, trauma, and ergotism.' Of these, arteriosclerosis obliterans is by far the most frequently eiicountered. Although differing clinically and pathologically, all of the diseases are similar in that they cause isehemia of tissues supplied by the occluded arteries. The degree of iseheinia is directly proportional to the rapidity of development and the extent of occlusion and is inversely proportional to the extent and rapidity of developnient of collateral arterial anastonioses. The isehemia may be increased by arteriolar constriction and decreased by arteriolar dilatation from aiiy cause. When blood flow diminishes to the point where tissue does not receive sufficient oxygen to sustaiii life, or when injury or ilifection inereases the demand for oxygen that the occluded arteries are uiiable to supply, gangrene occurs. It is beyond the scope of this presentation to discuss in detail the distinguishing features of the various chronic occlusive arterial diseases. Although much of what follows pertains to all or some of these diseases, most of it deals more specifically with thromboangiitis obliterans (TAO) * and with arteriosclerosis obliterans (ASO) .* Recently the concept of TAO as a diagnostic entity has been vigorously challenged and defended on both clini-