History of ECP Therapy
Kantrowitz and Kantrowitz first described the principle of “phase shift diastolic augmentation”, in 1953. Physicians and physicists at Harvard and elsewhere related this principle to oxygen consumption and cardiac workload. This understanding led to the concept of mechanically induced “cardiac assistance” for patients with low cardiac output syndromes, especially cardiogenic shock.
Beginning in the 1960’s, research on mechanically induced “cardiac assistance” followed tow distinct paths, one involved the use of a balloon positioned inside the descending thoracic aorta that would inflate during diastole and deflate at the onset of systole and another that involved the external compression and release of the vascular beds in the lower limbs. The first came to be known as the intra-aortic balloon pump or IABP. The second evolved into what is now referred to as external counterpulsation. These early systems were somewhat primitive by today’s standards, but both forms of counterpulsation clearly demonstrated the potential for increasing survival of patients with myocardial infarction and cardiogenic shock as well as for relief of angina pectoris.
Early hydraulic systems for external counterpulsation eventually gave way to pneumatics. This, along with refinements of the compression elements of the system, helped to improve outcomes and patient comfort.
The National Institutes of Health (NIH) played a significant role in the evolution of modern external counterpulsation systems by advocating the addition of a second cuff and the use of sequential cuff inflation to increase the amount of blood being returned to the heart and, as a result, diastolic augmentation. During the 1970’s, Zheng and associates at Sun Yat-sen University in China reported on a newly designed 3 stage pneumatic pulsation system. In these trials, effects of sequenced cuff inflation were studied in patients with angina pectoris and myocardial infarction. In more than 90% of 200 patients with angina, the system provided long-term symptomatic relief with minimal relapse, following 36 hours of treatment.
The favorable results reported by the Chinese group led scientists at the State University of New York at Stony Brook, to reassess the efficacy of external counterpulsation in treating patients with angina pectoris using a new “enhanced” counterpulsation system.
ECP, enhanced external counterpulsation, employs a three-cuff compression configuration and a sophisticated computerized control of the inflation/deflation sequence. This enhanced system has been shown to provide sustained relief of angina, and improvement in myocardial perfusion documented by nuclear imaging.