EVIDENCE OF VASCULAR GROWTH-ASSOCIATED WITH LASER TREATMENT OF NORMALCANINE MYOCARDIUM

Background. Transmyocardial laser revascularization is a new therapy f or patients with refractory angina. Although clinical studies suggest that transmyocardial laser revascularization decreases angina and may improve regional blood flow, the underlying mechanisms are not elucida ted We hypothesized that one mechanism may relate to stimulation of va scular growth in laser-treated regions. Methods. Transmyocardial laser revascularization channels were made with holmium:yttrium-aluminum ga rnet or carbon dioxide lasers in eight normal canine hearts; animals w ere sacrificed 2 to 3 weeks later and examined for vascular density an d for evidence of smooth muscle proliferation. Results. The original c hannels were infiltrated by granulation tissue with associated vascula rity. Vascular growth was stimulated immediately surrounding the chann el remnant as evidenced by an increase in the number of vessels (appro ximately twice that of the control region) and an increase in the numb er of vascular cells staining positive for markers of cellular prolife ration. Conclusions. Transmyocardial laser revascularization leads to local vascular growth as early as 2 weeks after treatment. It remains to be determined whether this mechanism contributes to increased regio nal blood flow or to clinical benefits associated with this novel form of therapy. (C) 1998 by The Society of Thoracic Surgeons.