How does ECP work?
Amazingly, the exact mechanism of action is not clearly understood. However, research is currently underway to determine this elusive mechanism of action. It is known that the treated cells stimulate or modify the patient’s own immune system to fight the disease. The response observed could not be due to the anti-proliferative (prevention of cancer cell growth) effect since only 3-5% of the body’s total lymphocyte population are treated during one ECP therapy. As a result of the photosensitized WBC exposure to UVA light, cellular damage occurs, altering cellular DNA and resulting in apoptotic cell death (programmed cell death). When these altered or damaged cells are returned to the patient, the immune system is alerted and becomes sensitized to the changed cells. The patient’s own immune system may also work to repair the cellular damage, further sensitizing the immune system to antigens (foreign material) now more visible to the immune system.
Patients usually receive ECP treatment for 35 hours, divided into one or two 60-minute treatment sessions five days per week. Patients who undergo two treatment sessions in one day require rest between sessions. Treatment is administered on a padded table, where three sets of electronically controlled inflation and deflation valves are located. These valves are connected to adjustable cuffs that are wrapped firmly, but comfortably, around the calves, the lower thighs, and the upper thighs and buttocks. Patients wear special pants during the sessions to minimize the possibility of skin irritation. Inflation and deflation of the cuffs is triggered by the patient’s EKG signal. At the onset of diastole, the cuffs inflate rapidly and sequentially, starting from the calves and proceeding upward to the buttocks. This increases diastolic pressure; thereby increasing coronary artery perfusion pressure and blood flow to the heart muscle.
ECP may work in several ways. The pills either keep the ovary from releasing an egg, thicken cervical mucus, or change the lining of the uterus in such a way that a fertilized egg may not attach and develop into a pregnancy. These emergency pills prevent pregnancy about 76-99% of the time, depending on when in the cycle unprotected intercourse takes place. You may notice a difference in your next period (e.g. early, late, lighter or heavier) if you take ECP. Once you have taken ECP, if you see a clinician for any reason before your next period, you should tell him/her that you have taken the pills.
