title: Transmyocardial Laser Revascularization Enhances Blood Flow within Bypass Grafts.
abstract: OBJECTIVE
  : Early benefits from transmyocardial laser revascularization (TMR) may be related to acute sympathetic denervation. This study hypothesized that TMR as an adjunct to off-pump coronary artery bypass (OPCAB) would improve myocardial runoff in the TMR-treated regions and increase graft flow.
  
  
  METHODS
  : Graft blood flow was measured in 145 consecutive OPCAB patients. In patients with graft flow <40 mL/min (n = 25), the myocardial region served by the graft was treated with TMR. Blood flow was reassessed 10 minutes after TMR and compared with graft flow in the nontreated regions. Postoperative outcomes, transcardiac thrombin production, coagulation activation, myocardial, and inflammatory markers were assessed. A control group not treated with TMR (n = 14) was selected with similar graft flows and other baseline characteristics.
  
  
  RESULTS
  : Risk factors, comorbidities, and preoperative medications were similar in all groups. TMR led to a 48% increase in bypass graft flow in 12 patients, but no significant change in flow in the remainder (n = 13). The control group also showed no change in graft flow measured during the same time-points. Compared with those that did not respond to TMR, responders showed a greater drop in pH during warm ischemia caused by distal anastomoses during OPCAB and significantly higher transcardiac gradients of F1.2, IL-8, TNFα, and VCAM.
  
  
  CONCLUSIONS
  : TMR acutely improves venous bypass graft flow in regions with more severe myocardial acidosis and inflammation during and after OPCAB. Acute sympathetic denervation after TMR may provide mechanistic insight into the early clinical benefits of TMR as an adjunct to OPCAB.
authors.affiliation: From the Division of Cardiac Surgery, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland.
authors.forename: Richard
authors.initials: R
authors.lastname: Tran
authors.forename: Philip S
authors.initials: PS
authors.lastname: Brazio
authors.forename: Seeta
authors.initials: S
authors.lastname: Kallam
authors.forename: Junyan
authors.initials: J
authors.lastname: Gu
authors.forename: Robert S
authors.initials: RS
authors.lastname: Poston