Transmyocardial Laser Revascularization Research Articles

Cardiac nociceptive reflexes after transmyocardial laser revascularization: Implications for the neural hypothesis of angina relief

Objective: The mechanism by which transmyocardial laser revascularization relieves angina is not understood. One theory is that laser-induced thermal damage to cardiac nerves results in cardiac denervation. This study examined the acute effects of transmyocardial laser revascularization on reflex responses mediated by cardiac nociceptors, the left ventricular receptors with sympathetic afferent fibers that are thought to mediate anginal chest pain. Methods: Experiments were performed in 13 chloralose-anesthetized dogs with sinoaortic denervation and vagotomy. Left ventricular receptors with sympathetic afferent fibers were activated by epicardial and intracoronary bradykinin before and 45 minutes after transmyocardial laser revascularization. Reflex responses elicited by bradykinin were quantitated by direct recording of efferent renal sympathetic nerve activity. Transmyocardial laser revascularization was performed in the open-chest model with a hand-held holmium:YAG laser (2.1-μm wavelength). Results: An average of 44.5 ± 1.0 channels were created. Before transmyocardial laser revascularization, reflex increases in renal sympathetic nerve activity were elicited by both epicardial and intracoronary bradykinin. After transmyocardial laser revascularization, there was no significant attenuation in the reflex responses to either epicardial (before, 66% ± 8%; after, 100% ± 24%; P =.19) or intracoronary (before, 124% ± 37%; after, 108% ± 25%; P =.44) bradykinin. Conclusions: Transmyocardial laser revascularization has no significant short-term effect on reflexes mediated by left ventricular receptors with sympathetic afferent fibers in anesthetized dogs. These results indicate that transmyocardial laser revascularization does not acutely interrupt the afferent nerves, which are believed to transmit the perception of anginal pain.

Extent of myocardial tissue damage during transmyocardial laser revascularization with the CO2 Heart Laser.

Transmyocardial laser revascularization (TMR) is the only surgical treatment for patients with severe diffuse coronary artery disease, who are not candidates for bypass grafting or percutaneous angioplasty. However, vaporization of tissue during the creation of channels leads to a certain loss of viable myocardium during every TMR procedure. We analyzed serum levels of creatine kinase and creatine kinase MB subtype in 163 patients after sole TMR with a CO2 laser (wave length 10.6 microm, 800-watt power). The control group consisted of 35 consecutive CABG patients and 30 consecutive redo-CABG patients. Additionally, in the TMR group we measured echocardiographically the left ventricular ejection fraction before and after TMR. We recorded the total amount of laser energy applied, average and maximum energy per channel, and the number of created channels, in order to calculate the correlation between these parameters and postoperative enzyme levels or changes in the LVEF. After TMR, we measured higher creatine kinase levels compared to those in CABG patients (607.8+/-558.4 U/L vs. 285.0+/-292.3 U/L, p < 0.01). The relative proportion of CK-MB of total CK, however, was significantly lower after TMR, compared to that of the control group (4.5+/-3.0% vs. 10.1+/-6.4%, p < 0.01). Patients with a pronounced postoperative increase in CK-MB levels or a higher percentage of CK-MB of total CK also after TMR operations show a decline in left ventricular contractility. In the laser group, the maximum enzyme levels were detected significantly later than in the control group (25.0+/-19.4 h postoperatively vs. 8.7+/-9.1 h, p < 0.01). There was no significant correlation between the technical laser parameters or the number of created channels and the percentage of CK-MB of total CK or changes in left ventricular ejection fraction. CO2 laser TMR does not result in significant injury to the myocardium. Cardiac enzymes play an important role in the detection of perioperative myocardial infarction in TMR patients.

Shedding light on denervation and transmyocardial laser revascularization

Shedding light on denervation and transmyocardial laser revascularization

First experience with hybrid percutaneous transmyocardial laser revascularization and angioplasty in patients with lesions at high risk for restenosis: Results of a phase I feasibility study

Background Prior studies have suggested that percutaneous transmyocardial laser revascularization (PTMR) may be effective as a sole treatment modality in reducing angina in patients with severe coronary artery disease and no revascularization alternatives. The safety and efficacy of the hybrid or adjunctive use of PTMR during the same procedure as percutaneous intervention (PCI) has not previously been reported. Methods A US phase I feasibility study was therefore performed to determine whether PTMR performed in the same myocardial territory as PCI is able to ameliorate symptomatic recurrence from restenosis. Results After successful and uncomplicated PCI in 26 patients with class III-IV angina and lesion(s) at high risk for restenosis, PTMR was performed in the same myocardial territories subtended by the treated vessel(s). Major periprocedural adverse events (death, Q-wave myocardial infarction, and bypass surgery) occurred in 3 (11.5%) patients, as the result of subacute vessel closure in 2 patients, and tamponade in the third. Cumulative 6-month mortality rate was 19.2%, including 2 late deaths between 3 and 4 months after discharge (1 death caused by late stent closure and 1 unexplained death during sleep.) Late repeat revascularization for restenosis in the PCI plus PTMR treated target vessel was required in 19.2% of patients, and an additional 11.5% of patients had class III-IV angina at 6-month follow-up. Conclusions These data demonstrate that in a patient population at high risk for restenosis, recently created PTMR channels are not protective against severe ischemia caused by acute vessel closure and that late symptomatic restenosis after PCI may still frequently occur despite PTMR in the same region. (Am Heart J 2001;142:679-83.)

Laser revascularisation.

Patients who present with angina pectoris due to underlying coronary artery disease which is not controlled by medical therapy, and who have disease which is not amenable to conventional forms of revascularisation, present an increasing clinical problem. Laser techniques have been introduced to improve myocardial perfusion in this group of patients. The surgical technique of transmyocardial laser revascularisation has been evaluated in this patient population. Generally, there has been a good symptomatic response in terms of improvement in angina, and in some studies an increase in exercise capacity. The technique, however, does carry significant morbidity and mortality. More recently, a catheter-based technique has been introduced--percutaneous myocardial laser revascularisation. This technique seems to improve symptoms of angina, produce an increase in exercise capacity, with a much more favourable procedural risk profile.

Variability of myocardial perfusion defects assessed by thallium-201 scintigraphy in patients with coronary artery disease not amenable to angioplasty or bypass surgery

OBJECTIVESWe sought to assess the variability of results obtained with thallium scintigraphy as a method for tracking the extent of myocardial ischemia in medically refractory patients with angina who are not suitable for coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty.BACKGROUNDNew therapies are being evaluated for patients with “no option” angina in whom medical therapy has failed. Nuclear techniques, like thallium scintigraphy, are used in multicenter trials to evaluate whether such therapies improve myocardial perfusion. However, the variability of test results is unknown in this patient group in a multicenter study.METHODSThe Angina Treatments: Lasers And Normal Therapies In Comparison (ATLANTIC) study was a randomized trial of transmyocardial laser revascularization (n = 182). Patients underwent dipyridamole thallium stress tests at baseline and 3, 6 and 12 months after enrollment. The control group (n = 90) was treated with constant medical therapy during the study and is a relevant group to investigate test variability. Test variability over time was quantified by the mean absolutechange in the percentage of reversible perfusion defects between baseline and follow-up.RESULTSBaseline percent myocardium with ischemia averaged 17.0 ± 13.7% and did not change during follow-up. However, variations in the percent myocardium with reversible perfusion defects over time amounted to an average of 6 to 8 percentage points, or 43% to 55% of the baseline value. Only ∼13% of this variability was attributable to variability in image reconstruction and analysis.CONCLUSIONSAs demonstrated in the ATLANTIC study, percent myocardial ischemia in control subjects receiving constant medical therapy varied in individual patients by an average of ∼50%. This may limit the utility of thallium scintigraphy to detect improved myocardial perfusion over time in response to therapy.

Transmyocardial laser revascularization remodels the intrinsic cardiac nervous system in a chronic setting.

Prospective trials have demonstrated that transmyocardial laser revascularization (TMLR) imparts symptomatic relief to patients with refractory angina. Because peak clinical effectiveness of TMLR is usually delayed by several months, it has been proposed that ventricular denervation is one mechanism whereby TMLR imparts symptomatic relief. We have demonstrated that TMLR does not denervate the heart in the acute setting, nor does it modify the intrinsic cardiac nervous system (ICNS) in the acute setting. However, the long-term effects of TMLR on the ICNS remain unknown. A holmium:yttrium-aluminum-garnet laser created 20 channels through the anterolateral left ventricular free wall of 10 dogs. Four weeks later, the function of cardiac sensory inputs to the ICNS was studied by applying veratridine (7.5 micromol/L) to ventricular sensory fields. Chronotropic and inotropic responses elicited by cardiac sympathetic or parasympathetic efferent neurons stimulated electrically (10 Hz, 4 V, 4 ms) or chemically (nicotine 5 to 20 microgram/kg IV) were also assessed. Chemical activation of epicardial sensory neurites with veratridine elicited expected ICNS excitatory responses. Electrical stimulation of sympathetic and parasympathetic efferent neurons induced expected altered cardiac responses. In contrast, the responsiveness of the ICNS to systemically administered nicotine was obtunded. Although chronic TMLR does not affect cardiac afferent or extracardiac efferent neuronal function, it does "remodel" the ICNS so that its responsiveness to a known potent chemical agonist (ie, nicotine) becomes obtunded. Remodeling of the ICNS may account in part for the delayed symptomatic relief that TMLR imparts to patients with refractory angina.

Transmyocardial Laser Revascularization Remodels the Intrinsic Cardiac Nervous System in a Chronic Setting

Background Prospective trials have demonstrated that transmyocardial laser revascularization (TMLR) imparts symptomatic relief to patients with refractory angina. Because peak clinical effectiveness of TMLR is usually delayed by several months, it has been proposed that ventricular denervation is one mechanism whereby TMLR imparts symptomatic relief. We have demonstrated that TMLR does not denervate the heart in the acute setting, nor does it modify the intrinsic cardiac nervous system (ICNS) in the acute setting. However, the long-term effects of TMLR on the ICNS remain unknown. Methods and Results A holmium:yttrium-aluminum-garnet laser created 20 channels through the anterolateral left ventricular free wall of 10 dogs. Four weeks later, the function of cardiac sensory inputs to the ICNS was studied by applying veratridine (7.5 μmol/L) to ventricular sensory fields. Chronotropic and inotropic responses elicited by cardiac sympathetic or parasympathetic efferent neurons stimulated electrically (10 Hz, 4 V, 4 ms) or chemically (nicotine 5 to 20 μg/kg IV) were also assessed. Chemical activation of epicardial sensory neurites with veratridine elicited expected ICNS excitatory responses. Electrical stimulation of sympathetic and parasympathetic efferent neurons induced expected altered cardiac responses. In contrast, the responsiveness of the ICNS to systemically administered nicotine was obtunded. Conclusions Although chronic TMLR does not affect cardiac afferent or extracardiac efferent neuronal function, it does “remodel” the ICNS so that its responsiveness to a known potent chemical agonist (ie, nicotine) becomes obtunded. Remodeling of the ICNS may account in part for the delayed symptomatic relief that TMLR imparts to patients with refractory angina.

Sustained Angina Relief 5 Years After Transmyocardial Laser Revascularization With a CO 2 Laser

Background Although transmyocardial laser revascularization (TMR) has provided symptomatic relief of angina over the short term, the long-term efficacy of the procedure is unknown. Angina symptoms as assessed independently by angina class and the Seattle Angina Questionnaire (SAQ) were prospectively collected up to 7 years after TMR. Methods Seventy-eight patients with severe angina not amenable to conventional revascularization were treated with a CO 2 laser. Their mean age was 61±10 years at the time of treatment. Preoperatively, 66% had unstable angina, 73% had had ≥1 myocardial infarction, 93% had undergone ≥1 CABG, 42% had ≥1 PTCA, 76% were in angina class IV, and 24% were in angina class III. Their average pre-TMR angina class was 3.7±0.4. Results After an average of 5 years (and up to 7 years) of follow-up, the average angina class was significantly improved to 1.6±1 ( P =0.0001). This was unchanged from the 1.5±1 average angina class at 1 year postoperatively ( P =NS). There was a marked redistribution according to angina class, with 81% of the patients in class II or better, and 17% of the patients had no angina 5 years after TMR. A decrease of ≥2 angina classes was considered significant, and by this criterion, 68% of the patients had successful long-term angina relief. The angina class results were further confirmed with the SAQ; 5-year SAQ scores revealed an average improvement of 170% over the baseline results. Conclusions The long-term efficacy of TMR persists for ≥5 years. TMR with CO 2 laser as sole therapy for severe disabling angina provides significant long-term angina relief.

Transmyocardial laser revascularization.

Low-powered lasers were first used in the early 1980s to produce transventricular channels as an adjunct to coronary artery bypass graft surgery (CABG). Early results were encouraging, but because of the combined procedure, could not be attributed directly to use of the laser [1]. High-powered lasers were introduced into clinical practice in 1990 [2]. These lasers are powerful enough to create a transmyocardial channel with minimal thermal damage to surrounding tissues [3]. Clinical studies, using transmyocardial laser revascularization (TMR) as the sole operative therapy for patients with severe and diffuse coronary artery disease (CAD) who have Class III or IV angina, and are on medical therapy, have been conducted since 1993. Based on the results of these studies, the FDA granted approval for the use of TMR as a sole therapy. Clinical studies are currently underway to assess the results of combined TMR and CABG [4]. Results of four controlled randomized studies have been published [5-8]. The data from two of these studies formed the basis for FDA approval of two different types of laser systems. The results of these studies have not provided any additional insights into the mechanism of action of TMR, which remains the Achilles' heel of this procedure. In this review, background information about the TMR procedure will be discussed along with an analysis of the recently published randomized studies.

Transmyocardial laser revascularization dose response: enhanced perfusion in a porcine ischemia model as a function of channel density

Background. Transmyocardial laser revascularization (TMR) appears to provide symptomatic relief to patients with ischemic heart disease, but evidence that TMR enhances perfusion to ischemic myocardium remains limited. Furthermore, it is uncertain whether there exists a TMR dose–response relationship that is a function of channel number. We therefore compared restoration of blood flow as analyzed by rest and stress 99mTc-sestamibi scans and histologic grading of neovascularization after 50-channel, 25-channel, or 10-channel TMR using the excimer laser in an established model of porcine myocardial ischemia. Methods. Yorkshire swine underwent a thoracotomy and placement of an ameroid constrictor around the proximal circumflex coronary artery. Three weeks later, the animals underwent resting and adenosine stress 99mTc-sestamibi scans for evaluation of ischemia immediately before repeat thoracotomy and TMR with either 50 channels (n = 4), 25 channels (n = 4), or 10 channels (n = 4) in the circumflex territory. The animals underwent repeat perfusion analyses 4 weeks later, after which the animals were sacrificed and the hearts were perfusion fixed for histologic evaluation of neovascularization. Results. All animals survived to sacrifice. Semiquantitative analyses of the sestamibi perfusion scans 4 weeks after lasing demonstrated significant improvement ( p < 0.04) in stress-induced ischemia in the 50-channel TMR animals, but not in the 25- or 10-channel TMR groups, as compared with scans obtained immediately before lasing. A computerized image analysis of perfusion scans similarly demonstrated an improvement in the area of ischemia of 42% ± 22% in the scans obtained 4 weeks after lasing compared with scans obtained immediately before lasing in the 50-channel group ( p < 0.004), but only a 12% ± 9% improvement in the 25-channel group and an 8% ± 4% improvement in the 10-channel group ( p > 0.05). Histologic assessment of neovascularization demonstrated significantly greater number of microvessels per low-power field in the 50- versus the 25- and 10-channel groups ( p < 0.001). Conclusions. In an animal model of myocardial ischemia, TMR appears to enhance myocardial perfusion. A dose–response relationship related to channel number may be of significance when evaluating the efficacy of various treatment strategies.

Invited commentary

It is in fact rather amazing that few have looked at the dose-response relationship in all the experimental studies and clinical trials for transmyocardial laser revascularization (TMR) until this time. No new drug would have been accepted and approved without dose-response data. Perhaps this is because we surgeons are more used to an all-or-none response: you do not worry about dose-response when you repair a valve or close a ventricular septal defect (VSD). Studying the outcome of laser TMR as a function of channel density allows one to choose the optimal number of laser punctures that should be made. Otherwise it is simply arbitrary. But in the case of TMR, there is another reason why such a study may be important. In spite of the FDA approval of this procedure and reports from centers worldwide of its efficacy in reducing anginal symptoms, the reasons why such results are obtainable remains highly controversial. The most serious challenging data come recently from the first blinded randomized DIRECT trial [1Leon MB, et al. DMR (direct myocardial revascularization) in Regeneration of Endomyocardial Channels Trial (DIRECT). Presented at the American College of Cardiology, 50th Annual Scientific Session, Orlando, FL, March 18, 2001.Google Scholar]. During cardiac catheterization, patients were randomized in a blinded fashion to receive low-dose or high-dose density (10 to 15 and 20 to 25 channels per zone) endocardial laser punctures or a mock procedure. Although improvements were noted across all study groups, the investigators reported no difference in functional and symptomatic responses among these groups, suggesting a significant placebo effect. The dose-response findings in such a study are valuable in strengthening the possibility that the procedure and outcome may or may not have a cause-and-effect relationship, rather than merely an association. This interesting paper by Hamawy and colleagues raises many additional questions. They showed that the densities of excimer laser channels created from the epicardial side in an ischemic myocardial segment had a positive relationship with the magnitude of neovascularization and increased blood flow. The contradiction between this observation and the results of DIRECT trial may be because the endpoints looked at in this study (angiogenesis) are not relevant to the clinical outcome endpoints for the DIRECT trial (angina relief and functional improvement); or because the route of TMR (epicardial versus endocardial approach) or the laser energies used were different. But if so, how? Furthermore, if the angiogenesis induced by TMR is due to an inflammatory response following tissue trauma created by laser punctures, why not use a cheap needle, which can also cause similar although less trauma and angiogenesis, and simply increase the puncture density to match the effect of a laser? The intense scrutiny that TMR continues to receive is appropriate. If this procedure, which requires the use of an expensive device, is not valid, we should know. On the other hand, solid confirmation of this approach will justify its wider application in order to offer relief for patients who suffer from intractable angina.

Transmyocardial channeling

Transmyocardial channeling

Primary Transmyocardial Laser Revascularization for End-Stage Coronary Artery Disease

Ahhough popularized only recently, transmyocardial laser revascularization (TMR) has a lfistory spanning four decades. Sen introduced the concept of myocardial acupuncture in tile mid-1960s, 1 but it was overshadowed by tile remarkable results obtained with direct coronary revascularization via coronary artery bypass grafting (CABG). Tile use of tile laser for this purpose was l,ursued through tile 1980s by Mirhoseini and colleagues2; however, it was only in the 1990s, with substantial industry support, that sufficient eliuical experience with TMR was accumulated to generate widespread interest and enthusiasm for this therapy, a,4 Intrigued by reports of what can only be called dranmtie an~na relief obtained with carbon dioxide (C02) laser systems in the early 1990s, we initiated our involvement with TMR at Waslfington University in February 1996. We participated in the phase I trial of a new holmium: YAG system (Eclipse Surgical Technologies Inc., Sunnyvale, CA) and were the first to use this particular energy source clinically for TMR in the United States. Our experience was encouraging. The results of this and other trials of the CO 2 and holmium: YAG systems lead to FDA approval of both types of devices for clinical use in the treatment of an~na pectoris and to Medicare reimbursement for the same. As such, these devices llave become a part of our armamentariuln for the management of advanced coronary artery disease. However, their place is strictly limited in our view and their uhilnate role remains uncertain.

Thoracoscopic Transmyocardial Laser Revascularization

Transmyocardial laser revascularization has been used to treat patients with end-stage coronary artery disease and severe disabling angina. Typically, the operative approach is through a left anterior thoracotomy. I report a case of transmyocardial laser revascularization performed thoracoscopically.

Primary transmyocardial laser revascularization for end-stage coronary artery disease

Primary transmyocardial laser revascularization for end-stage coronary artery disease

Excimer laser (308 nm) based transmyocardial laser revascularization: Effects of the lasing parameters on myocardial histology

The effect of the excimer laser (308 nm) parameters on transmyocardial revascularization (TMR) channels is not well defined. This study investigates the influence of the pulse repetition rate, the size of the delivery catheter and its advancement speed on the morphology of TMR channels in vivo. Myocardial ablation was performed in a porcine model (N = 27) using multifiber catheters of 1.0 and 1.4 mm in diameter. The catheters were advanced into the myocardium at different speeds (1.27 and 2.54 mm/sec) while ablating at various repetition rates (10-80 Hz). The radiant exposure was kept at 35 mJ/mm(2) throughout the experiments. The channel histology was quantified by digital microscopy. The channel cross-sectional area and the extent of the thermal damage decrease as the catheter advancement speed exceeds the ablation speed and vice versa. Within the parameters tested, advancement speed of about 1.3 mm/sec and pulse repetition rates of 40 Hz produce channels of size comparable to the catheter's diameter with moderate thermomechanical damage. The repetition rate, catheter size, and catheter advancement speed are closely intertwined and crucial to the histological outcome of excimer laser based TMR.

Transmyocardial laser revascularization in ischemic cardiomyopathy

Background In ischemic cardiomyopathy (left ventricular ejection fraction [LVEF] ≤30%), myocardial revascularization by coronary artery surgery has better results than heart transplantation, provided there is sufficient ischemic but viable myocardium. The mode of action of transmyocardial laser revascularization (TMR) is still being debated, but if the procedure induces improved myocardial perfusion it could be a “bridge,” or alternative, to heart transplantation. Methods We retrospectively analyzed 194 patients, who underwent TMR between July 1997 and October 1999. Patients with TMR as an adjunct to coronary artery surgery ( n = 30) and those who did not provide written consent to the procedure ( n = 8) were excluded; 126 patients had normal or moderately reduced left ventricular function, and 30 patients with ischemic cardiomyopathy (LVEF ≤30%) were included. Results After 12 months, the Canadian Cardiovascular Society (CCS) score dropped significantly from 3.6 (3 to 4) to 2.4 (1 to 4) and maximum work load increased significantly from 58 W (25 to 100 W) to 73 W (25 to 120 W). However, thallium score and LVEF did not improve significantly (27% [15% to 30%] to 32% [15% to 45%]). Prior to the TMR procedure, all 30 patients had a “low risk” or “medium risk” of death according to the Aaronson classification. The 30-day, 1-year, and 2-year survival rates were 83%, 50%, and 47%, respectively. Conclusions We conclude that TMR in ischemic cardiomyopathy (LVEF ≤30%) has a perioperative risk comparable to that for heart transplantation, but there is no improvement of myocardial performance or life expectancy. Therefore, TMR cannot be regarded as a “bridge,” or alternative, to transplantation. However, in individual cases with contraindications for transplantation the anti-anginal effect may justify use of the procedure.

Influence of the Availability of Laser Transmyocardial Revascularisation on Surgical Strategy in Patients with Advanced Coronary Artery Disease

Objective: To compare the planned and actual revascularisation techniques used in patients undergoing cardiac surgery for refractory angina when excimer transmyocardial laser revascularisation (TMR) is available. Methods: Observational series of 31 patients (mean age 65 years) with severe angina [mean CCS score (SD) 3.8 (0.4)] and three-vessel coronary artery disease judged unsuitable for conventional bypass surgery alone. All patients underwent cardiac surgery: revascularisation techniques were determined by the operative findings. Results: Pre-operative strategy was altered by the intra-operative findings in 13 patients (42%). In 5 (16%), the coronary vessels proved graftable and TMR was unnecessary. Conversely, in 6 patients (19%) an anticipated graft could not be performed and TMR was used as an alternative. In 2 patients (7%), neither strategy was possible. Overall, TMR was performed as a stand-alone procedure in 9 (29%) and combined with CABG in 17 (55%). Operative mortality was low: 0% at 30 days and 6% at 6 months. Mean CCS class (SD) improved post-operatively from 3.8 (0.4) to 1.7 (1.1) (p < 0.01). Conclusions: The pre-operative coronary angiogram is an imperfect predictor of which coronary vessels are suitable for grafting. The availability of laser TMR allows the cardiac surgeon to accept cases which would otherwise be considered inoperable and to respond better to intraoperative findings. The combination of laser TMR and bypass grafts provides good short- and medium-term symptomatic improvement with a low post-operative mortality.

Microperfusion Enhancement after TMLR in Chronically Ischemic Porcine Hearts

Objective. The purpose of this study was to determine the effect of transmyocardial laser revascularization (TMLR) on myocardial perfusion and function in chronically ischemic myocardium. Methods. In the first operation a stenosis of the left anterior descending artery was created in 20 open-chest anesthetized pigs to implement this ischemic model. In contrast, four pigs served as controls (thoracotomy only). Seven days later (2nd operation), all animals were studied at baseline by analyzing different parameters of perfusion (radioactive microspheres), function, and intramyocardial pressure. Afterwards, pigs who received a left anterior descending artery stenosis were randomized into one of three groups: animals in laser group 1 ( n = 7) received one and in laser group 2 ( n = 7) two laser channels per cm2 in the left anterior descending artery territory. Animals of the ischemic group ( n = 6) underwent the same procedures without transmyocardial laser revascularization. Three months later, the animals were re-studied (3rd operation) and additional analysis of histochemistry and myocardial water content was performed. Results. Regional myocardial blood flow (RMBF) in laser group 2 revealed statistically higher RMBF values compared to the ischemic group (0.39±0.13 versus 0.14±0.12 ml/min/g; P = 0.043), after 3 months, whereas the absolute RMBF had not increased compared to the 1-week baseline values. Left ventricular stroke work index (LVSWI) at rest and under stress did not show any improvement compared to the initial values in all study groups ( P = ns). Nevertheless, laser group 1 demonstrated relatively higher LVSWImax values compared to the ischemic (1.33±0.19 versus 0.93±0.16 mJ/kg; P = 0.03) and laser group 2 (1.33±0.19 versus 1.02±0.15; P = 0.024). Regional contractility of laser groups 1 and 2 recovered after 3 months (which had deteriorated shortly after transmyocardial laser revascularization) and increased under stress (100% versus 144.33±46.42, P = 0.029 and 100% versus 116.26±21.06, P = 0.034; respectively). In contrast, the corresponding ischemic group values were not different from intial values ( P = ns). Conclusions. This model of chronic regional ischemia demonstrates that CO2-laser revascularization significantly improves microperfusion and regional function, whereas the overall perfusion and global LV function is unchanged.