The authors report the effects of laser rays, the different kinds of rays and their interaction with biological tissues. The use of laser rays in medicine, from photocoagulation experimental studies in the animal retina to their use in atheroma plaques and the cardiac muscle is also reported, with emphasis on the pioneer studies carried out in Brazil. Indirect methods of myocardial revascularization, the basis for the use of laser rays in transmyocardial revascularization surgery are reported as well, in addition to randomized protocols which have shown this procedure is adequate for the treatment of a selected group of patients. A special emphasis is given to the kind of patient chosen for revascularization using laser, i.e., patients in end-stage coronary artery disease, with ischemic (and viable) myocardium with angina, after all the usual therapy resources have been tried, especially classic myocardial revascularization and angioplasty. The experience of the Heart Institute in a two-year period consists of 40 patients with the clinical characteristics above, who underwent transmyocardial revascularization using laser rays. After 12 months of follow-up, about 87.8% of them have a significant improvement of symptoms, with regression of class III or IV angina to classes 0, I or II (p<0.0001). Three (7.5%) early deaths and 2 late deaths were observed. Despite a mild improvement in left ventricular function, shown by magnetic resonance and echocardiographic study, there was no change in myocardial perfusion. The fate of the channels created by laser rays in the myocardium is studied based on our own results and in literature. The probable activity mechanisms are also discussed, emphasizing myocardial denervation and neoangiogenesis. Future perspective involves the use of laser in minimally invasive procedures combined to classic myocardial revascularization.
Myocardial revascularization; Laser surgery; Angina pectoris; Carbon dioxide
