Kamuran A. Kadipasaoglu

Transmyocardial laser revascularization: Results of a multicenter trial with transmyocardial laser revascularization used as sole therapy for end-stage coronary artery disease ☆ ☆☆ ★ ★★ ♢

BACKGROUND Transmyocardial laser revascularization was used as the sole therapy for patients with ischemic heart disease not amenable to percutaneous transluminal coronary angioplasty or coronary artery bypass grafting. This technique uses a carbon dioxide laser to create transmyocardial channels for direct perfusion of the ischemic heart. METHODS Since 1992, 200 patients, at eight hospitals in the United States, have undergone transmyocardial laser revascularization. The patients have a combined 1560 months of follow-up for an average of 10 +/- 3 months per patient. Their age was 63 +/- 10 years and their ejection fraction was 47% +/- 12%. Eighty-two percent had at least one previous bypass graft operation and 38% had a prior angioplasty. Preoperatively, the patients underwent nuclear single photon emission computed tomography perfusion scans to identify the extent and severity of their ischemia. These scans were repeated at 3, 6, and 12 months. Angina class, admissions for angina, and medications were recorded. RESULTS The perioperative mortality was 9%. Angina class decreased significantly from before treatment to 3, 6, and 12 months (p < 0.001). Likewise, there was a significant decrease in the number of perfusion defects in the treated left ventricular free wall. Concomitantly, there was a significant decrease in the number of admissions for angina in the year after the procedure when compared with the year before treatment (2.5 vs 0.5 admissions per patient-year). CONCLUSION These combined results indicate that transmyocardial laser revascularization provides angina relief, decreases hospital admissions, and improves perfusion in patients with severe coronary artery disease.

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

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.

Myocardial Revascularization With Laser Preliminary Findings

BACKGROUND We assessed the transmyocardial laser revascularization (TMLR) as sole therapy in patients with symptomatic coronary artery disease refractory to interventional or medical treatment. METHODS AND RESULTS Thirty-one patients were evaluated with positron emission tomography (PET), dobutamine echocardiography, 201Tl single-photon emission computed tomography (201Tl-SPECT), and multigated acquisition radionuclide ventriculography (MUGA). TMLR was performed in 21 patients who had demonstrable ischemia in viable myocardium. The mean Canadian Cardiovascular Society (CCS) angina class was 3.70 +/- 0.7 (4 patients with unstable angina). Untreated septal segments were used as controls. At 3 months, (n = 15 patients), the mean CCS angina class was to 2.43 +/- 0.9 (P < .05). On dobutamine echocardiography, the mean resting wall motion score index was improved by 16% in lased segments (P < .03 vs control), and mean LVEF at peak stress increased by 19% (P = NS vs baseline). On 201Tl-SPECT, perfusion of lased and nonlased segments did not change. On PET, the mean ratio of subendocardial to subepicardial perfusion (SEn/SEp) increased 14% over baseline (P < .001 vs control). At 6 months (n = 15 patients), the mean CCS angina class was 1.7 +/- 0.8 (P < .05). The mean resting wall motion score index was up by 13% in lased segments (P < .05 vs control). Resting LVEF was unchanged. Stress LVEF increased 21% (P = NS vs baseline). Myocardial perfusion remained unchanged by 201Tl-SPECT. On PET, 36% of the lased segments were better, and 25% were worse compared with baseline. The resting SEn/SEp by PET was up 21% (P < .001 vs control). All deaths (two perioperative and three late) occurred in patients with preoperative congestive heart failure. Two patients required repeat revascularization of new coronary lesions. CONCLUSIONS These results suggest that TMLR improves anginal status, relative endocardial perfusion, and cardiac function in patients who do not have preoperative congestive heart failure.

Laser–Tissue Interaction During Transmyocardial Laser Revascularization

BACKGROUND The clinical procedure known as transmyocardial revascularization has recently seen its renaissance. Despite the promising preliminary clinical results, the associated mechanisms are subject to much discussion. This study is an attempt to unravel the basics of the interaction between 800-W CO2 laser radiation and biological tissue. METHODS Time-resolved flash photography was used to visualize the laser-induced channel formation in water and in vitro porcine myocardium. In addition, laser-induced pressures were measured. Light microscopy and birefringence microscopy were used to assess the histologic characteristics of laser-induced thermal damage. RESULTS The channel depth increased logarithmically with time (ie, with pulse duration) in water and porcine myocardium. Pressure measurements showed the occurrence of numerous small transients during the laser pulse, which corresponded with channel formation, as well as local and partial channel collapse during the laser pulse. Twenty millimeters of myocardium was perforated in 25 ms. Increasing the pulse duration had a small effect on the maximum transversable thickness, but histologic analysis showed that thermal damage around the crater increased with increasing pulse duration. CONCLUSIONS Several basic aspects of the interaction of high-power CO2 laser radiation with myocardial tissue and tissue phantoms were studied in vitro. Although the goal of this study was not to unravel the mechanisms responsible for the beneficial effects of transmyocardial revascularization, it provided important information on the process of channel formation and collapse and tissue damage.

Refractory angina pectoris in end-stage coronary artery disease: Evolving therapeutic concepts ☆ ☆☆ ★

Refractory angina pectoris in coronary artery disease is defined as the persistence of severe anginal symptoms despite maximal conventional antianginal combination therapy. Further, the option to use an invasive revascularization procedure such as percutaneous coronary balloon angioplasty or aortocoronary bypass grafting must be excluded on the basis of a recent coronary angiogram. This coronary syndrome, which represents end-stage coronary artery disease, is characterized by severe coronary insufficiency but only moderately impaired left ventricular function. Almost all patients demonstrated severe coronary triple-vessel disease with diffuse coronary atherosclerosis, had had one or more myocardial infarctions, and had undergone aortocoronary bypass grafting (70% of cases). We present three new approaches with antiischemic properties: long-term intermittent urokinase therapy, transcutaneous and spinal cord electrical nerve stimulation, and transmyocardial laser revascularization.

Total heart replacement using dual intracorporeal continuous-flow pumps in a chronic bovine model: a feasibility study.

Continuous-flow pumps are small, simple, and respond physiologically to input variations, making them potentially ideal for total heart replacement. However, the physiological effects of complete pulseless flow during long-term circulatory support without a cardiac interface or with complete cardiac exclusion have not been well studied. We evaluated the feasibility of dual continuous-flow pumps as a total artificial heart (TAH) in a chronic bovine model. Both ventricles of a 6-month-old Corriente crossbred calf were excised and sewing rings attached to the reinforced atrioventricular junctions. The inlet portions of 2 Jarvik 2000 pumps were positioned through their respective sewing rings at the midatrial level and the pulseless atrial reservoir connected end-to-end to the pulmonary artery and aorta. Pulseless systemic and pulmonary circulations were thereby achieved. Volume status was controlled, and systemic and pulmonary resistance were managed pharmacologically to keep mean arterial pressures at 100±10 mmHg (systemic) and 20±5 mmHg (pulmonary) and both left and right atrial pressures at 15±5 mmHg. The left pump speed was maintained at 14,000 rpm and its output autoregulated in response to variations in right pump flow, systemic and pulmonary pressures, fluid status, and activity level. Hemodynamics, end-organ function, and neurohormonal status remained normal. These results suggest the feasibility of using dual continuous-flow pumps as a TAH.

Revascularization procedures in patients with transplant coronary artery disease.

OBJECTIVE To assess the efficacy of revascularization in cardiac transplant patients who developed de novo coronary artery disease. METHODS Eighteen patients underwent one or more of four methods of revascularization: percutaneous transluminal coronary angioplasty (PTCA), percutaneous transluminal coronary rotational atherectomy (PTCRA), coronary artery bypass grafting (CABG), and transmyocardial laser revacularization (TMLR). Eleven PTCA procedures were performed in 10 patients 55.3 +/- 6.6 months after transplantation. Six patients underwent PTCRA 83.3 +/- 11.2 months after transplantation. Five patients underwent CABG 54.0 +/- 12.6 months after transplantation; the mean left ventricular ejection fraction was 49.6 +/- 16.9 (20-65%); hypertrophy was present in two of these patients. One patient with distal coronary artery disease and New York Heart Association class IV symptoms underwent TMLR only. One patient underwent both CABG and TMLR because of triple vessel proximal disease, diffuse distal disease, and New York Heart Association class IV symptoms. RESULTS PTCA was successful in 10 procedures with decrease in mean stenosis from 87.7 +/- 2.7 to 24.3 +/- 6.0%. Follow-up, at 16.9 +/- 4.0 months, showed restenosis in two patients. PTCRA was successful in all patients with a decrease in mean stenosis from 83.4 +/- 4.4 to 11.7 +/- 1.9%. Short-term follow-up did not reveal reocclusion. Two CABG patients who had hypertrophy died of heart failure 2 and 9 days after their operations. One CABG patient with excellent cardiac function died after 15 days because of pulmonary failure. In one patient, left ventricular ejection fraction improved from 35 to 50%, and he is alive 64 months later. Six months after TMLR, the New York Heart Association class in one patient improved from IV to II, and his left ventricular ejection fraction improved from 29 to 42%. The ejection fraction in the patient who underwent both CABG and TMLR improved from 20 to 56% but the patient expired 7 weeks later. CONCLUSIONS It appears that revascularization procedures can be effective in patients with coronary artery disease after cardiac transplantation and that coronary angioplasty or atherectomy would be a therapy of choice for single proximal lesions. CABG should be used cautiously and only reserved for patients with multi-vessel disease without hypertrophy. Laser revascularization with or without bypass grafting has potential to become the therapy of choice for transplant coronary artery disease.

Long- and short-term effects of transmyocardial laser revascularization in acute myocardial ischemia

This study examined the effect of transmyocardial laser revascularization (TMLR) on infarct size and global and regional left ventricular (LV) function.

Transmyocardial Laser Revascularization in Allograft Coronary Artery Disease

We used transmyocardial laser revascularization to treat accelerated cardiac allograft atherosclerosis in 2 patients. One patient received transmyocardial laser revascularization as sole therapy, the other as an adjunct to coronary artery bypass grafting. The systolic function improved in both patients, although the patient who had adjunctive transmyocardial laser revascularization died of systemic infection and renal failure on postoperative day 55. The second patient is alive and well 1 1/2 years after the laser procedure. We discuss 4 other patients who received transmyocardial laser revascularization treatment elsewhere in the United States. Transmyocardial laser revascularization has the potential to become important in the treatment of transplant atherosclerosis. Randomized clinical trials are warranted to assess the efficacy of transmyocardial laser revascularization in this setting.

Biventricular support with the Jarvik 2000 ventricular assist device in a calf model of pulmonary hypertension.

The Jarvik 2000 ventricular assist device (VAD) is clinically efficacious for treating end-stage left ventricular failure. Because simultaneous right ventricular support is also occasionally necessary, we developed a biventricular Jarvik 2000 technique and tested it in a calf model. One VAD was implanted in the left ventricle with outflow-graft anastomosis to the descending aorta. The other VAD was implanted in the right ventricle with outflow-graft anastomosis to the pulmonary artery. Throughout the 30 day study, hemodynamic values were continuously monitored. On day 30, both pumps were evaluated at different speeds, under various hemodynamic conditions. By gradually occluding the pulmonary artery proximally or distally, we simulated varying degrees of high pulmonary vascular resistance, right ventricular hypertension, global heart failure, or ventricular fibrillation. The two VADs maintained biventricular support even during pulmonary artery occlusion and ventricular fibrillation, yielding a cardiac output of 3–11 L/min, left ventricular end-diastolic pressure of 11–24 mm Hg, and central venous pressure of 9–25 mm Hg. End-organ function was unimpaired, and no major adverse events occurred. The dual VADs offered safe, effective biventricular assistance in the calf. Additional studies are needed to assess the effects of lowered pulse pressure upon the pulmonary circulation and to develop a single pump speed controller.