About CTOs
One of the leading causes of human mortality is cardiovascular disease. This commonly begins with stenotic lesions of the coronary arteries, which occur, for example, as a result of the gradual buildup of atheromata, or plaques, along the vessel walls. This buildup leads to a gradual reduction in the diameter of the lumen over time and the subsequent restriction of blood flow.
A Chronic Total Occlusion results when a blood vessel becomes completely occluded by plaques for an extended period of time, typically defined as longer than three months. Such occlusions occur not only in coronary arteries but in other blood vessels as well. A CTO may contain soft plaques, but not infrequently a CTO develops hard plaques which comprise dense, fibrous tissue and calcification at the proximal and distal ends.
Chronic Total Occlusions are found in approximately one-third of patients with significant coronary artery disease. Until recently, the most common method of treating CTO was bypass surgery, which is a procedure that, unfortunately, involves considerable risk and trauma to the patient. However, in order to treat a CTO patient with minimally invasive therapy, a physician must first successfully cross the blockage and place the guidewire in the "true" lumen of the artery beyond the occlusion. Because some CTOs are comprised of hard, rock-like plaque, it can be very difficult for the physician to cross the blockage. As a result, it is not uncommon for the crossing device to be diverted outside of the true lumen and into the "false" lumen of the artery. The process of re-entering the true lumen can be arduous and extremely time consuming.