The first patient to participate in a clinical trial of a new laser heart surgery technique at University of Washington Medical Center is now recovering at home. The technique, called transmyocardial revascularization (TMR), creates new pathways for blood to reach oxygen-starved heart tissue in patients with coronary artery disease.
Dr. Edward D. Verrier, professor and chief of cardiothoracic surgery, used a “cold beam” laser to create numerous tiny channels in the myocardium (heart wall) of the left ventricle of a 69-year-old Seattle man who also underwent coronary artery bypass surgery. The patient, who was suffering from atherosclerosis (clogged arteries) and angina (chest pain), spent six days in the hospital following surgery. He is the first of 12 patients who will participate in phase one of the trials at UWMC.
While TMR has been performed before, this clinical trial, sponsored by United States Surgical Corporation, uses a unique xenon chloride excimer laser. Unlike other lasers that use heat and may cause thermal damage, the excimer laser produces a cold laser beam that minimizes trauma to surrounding tissue.
“Many patients have tremendous debilitating chest pain that cannot be treated with normal coronary artery bypass or interventional cardiology techniques,” said Verrier. “TMR may help a substantial number of patients with heart disease and this study will provide significant insights into TMR’s effectiveness in establishing blood supply to the heart muscle when used in conjunction with bypass surgery.
“We have not fully determined why TMR works, but we know from patient reports and articles published in the scientific literature that TMR appears to be succesful in relieving angina in patients with no other therapeutic options,” said Verrier.
Researchers offer four theories on TMR. They say laser channels may:
- allow the heart muscle to absorb oxygen directly from the blood in the left ventricle cavity;
- stimulate formation of new blood vessels in the heart muscle;
- induce scarring, thereby eliminating blood-starved areas of the heart muscle; or
- desensitize nerves in the heart muscle, relieving the pain of angina.
Participants will undergo a series of tests prior to and in the year following surgery to help doctors determine how TMR helps relieve patients’ symptoms. Some patients in the trial will have both bypass surgery and TMR; others will have only bypass surgery.
Other medical centers participating in the clinical trials are Allegheny University of Health Sciences in Pennysylvania and Loma Linda University Medical Center in California. All three sites are in the process of recruiting additional patients for the study.