Transmyocardial laser revascularization: Clinical experience with twelve-month follow-up

Abstract

We are investigating a new technique for myocardial revascularization in which an 800 W carbon dioxide laser is used to drill 1 mm diameter channels into a beating heart after left thoracotomy. Clotting occludes the channels on the subepicardium, and in the long-term setting, blood from the left ventricular cavity flows through these channels to perfuse the ischemic subendocardium. To test the efficacy of this technique in a preliminary clinical trial, we used it as sole therapy for 21 consecutive patients. All patients had hibernating myocardium, reduced coronary flow reserve, or both, had distal diffuse coronary artery disease, and had angina refractory to normal therapy. Eight patients were excluded from follow-up because of death (n=5), rerevascularization (n=2), or diaphragmatic paralysis resulting in postoperative respiratory incapacity (n=1). In the remaining 13 patients available for follow-up, the mean angina class (Canadian Cardiovascular Society) was 3.7 +/- 0.4 before operation and 1.8 +/- 0.6 12 months after operation (p < 0.01). Mean resting left ventricular ejection fraction was 48% +/- 10% before operation and 50% +/- 8% at 12-month follow-up. At 12 months, resting mean subendocardial/subepicardial perfusion ratio had increased by 20% +/- 9% in septal regions treated by laser but decreased by 2% +/- 5% in untreated regions (n=11, p <.001). These results suggest that revascularization by this laser technique positively affects subregional myocardial perfusion and may result in clinical benefits for patients with reversible myocardial ischemia. Studies to date have not demonstrated significant changes in global and regional ventricular contractile function.

Cardiac Sympathetic Denervation After Transmyocardial Laser Revascularization

“…Increased myocardial perfusion, directly through the patent channels or indirectly via laser-induced neovascularization, has been the main proposed mechanism of angina relief. Angina relief has been a consistent finding of most clinical studies 3,5,12,20,21 regardless of the kind of laser used, CO 2 or Ho:YAG. However, increased perfusion, channel patency, and neovascularization have all been very variable findings.…”

“…1 Results of clinical studies continue to show that TMR is effective in relieving angina. [2][3][4][5] However, the exact mechanisms by which TMR exerts its effects and relieves angina are still controversial. The main proposed mechanisms include direct blood flow from the ventricular cavity to the ischemic myocardium through laser-created channels 2,6,7 and increased myocardial blood flow through neovascularization mediated by thermal or mechanical laser injury.…”

“…[2][3][4][5] However, the exact mechanisms by which TMR exerts its effects and relieves angina are still controversial. The main proposed mechanisms include direct blood flow from the ventricular cavity to the ischemic myocardium through laser-created channels 2,6,7 and increased myocardial blood flow through neovascularization mediated by thermal or mechanical laser injury. 7,8 However, the majority of human and experimental studies have not been able to demonstrate histologically sustained patency of the channels created.…”

Therapy for Angina Pectoris Secondary to Coronary Disease

“…However, though several preliminary studies demonstrated a decrease in angina severity in most patients (Cooley et al, 1996;Horvath et al, 1996), subsequent randomized controlled trials (RCT) have reported contradictory results (Aaberge et al, 2000;Burkhoff et al, 1999;Campbell et al, 2001;Jones et al, 1999;March, 1999;van der Sloot et al, 2004). Briones et al (Briones et al, 2009) conducted a Cochrane systematic review to assess the efficacy and safety of TMR versus optimized drug therapy in alleviating angina and improving survival and heart function.…”

Digital Radiographic Quantification of Myocardial Blood Flow Around a Transmyocardial Laser Channel in Rabbit Hearts

“…Although histological, immunohistochemical and molecular studies in animal models have demonstrated the presence of angiogenesis in the myocardium surrounding the treated region, [3][4][5][6][7] the controversy continues as to whether or not TMLR can enhance myocardial perfusion in clinical settings. [8][9][10][11] Various modalities have been employed to assess myocardial perfusion in the TMLR-treated heart such as the microsphere technique, 3,5 positron emission tomography and Tc-sestamibi scintigraphy. [12][13][14] However, perfusion around an individual laser channel has not been analyzed because the required spatial resolution cannot be achieved through these methods.…”