Reoperative transmyocardial laser revascularization for late recurrent angina

Transmyocardial laser revascularization (TMR) reduces anginal class and is indicated for severely symptomatic patients who are not candidates for conventional revascularization. This report describes a 72-year-old man who presented 4 years following initially successful TMR with recurrent angina refractory to maximal medical management. Reoperative TMR was performed with substantial improvement in angina and functional class.     

Long-term outcome of cardiac allograft vasculopathy treated by transmyocardial laser revascularization: early rewards, late losses.

Transmyocardial laser revascularization (TLR) was initially touted as a promising therapeutic alternative for tackling the growing problem of cardiac allograft vasculopathy in late heart transplant survivors. We first described 4- and 8-week observations of application of this surgical technique, in which we professed enthusiasm for TLR in providing symptomatic relief and in reducing ischemic burden. In this report, we present the long-term (24-month) impact of TLR on clinical outcome, channel patency, and recrudescence of ischemic burden. In the long term, surgical TLR provides neither consistent symptomatic improvement nor an ameliorative effect on the natural history of cardiac allograft vasculopathy.     

Noninvasive characterization of myocardium after transmyocardial laser revascularization

AIM: The therapeutic mechanism of transmyocardial revascularization (TMR) is not yet fully understood, and continues to be a subject of controversy and active research. Immediate direct laser channel flow, gradual angiogenesis, denervation, and perioperative infarction of the ischemic area have been all discussed, without clear evidence indicating superiority of individual factors. METHODS: We utilized a prospective noninvasive physiologic dynamic method to assess laser-related myocardial injury. The study protocol included EKGs and echocardiograms, including intraoperative transesophageal echocardiograms (TEE) on consecutive TMR patients. CPK-MB was measured postoperatively, with 5 samples at 6-hour intervals. RESULTS: Fifty male patients averaging 62 years old were enrolled in the study. Two patients experienced postoperative myocardial infarctions, from which 1 died. The average CPK-MB values were 12.8+/-1.28 immediately after surgery, 19.2+/-2.4 at 6 h, 15.2+/-2.3 at 12 h, 12.2+/-6.3 at 18 h, and 11.7+/-1.3 at 24 h. In only 5 patients were the CPK-MB values over 30 units at their peak. The intraoperative wall motion remained unchanged in the patients studied, both using TEE and transthoracic echography. CONCLUSION: Significant myocardial injury after TMR appears unlikely, as indicated by CPK-MB and myocardial wall dynamics. Furthermore, TMR does not seem to aggravate baseline myocardial ischemia. We found no evidence to support a hypothesis that surgical myocardial injury constitutes the mechanism of therapeutic action in TMR.     

Factors influencing results and outcome after transmyocardial laser revascularization

Background. Transmyocardial laser revascularization (TMR) has been increasingly used during the recent past for patients with diffuse coronary artery disease. Because this operation is associated with significant morbidity and mortality, it is important to select patients for TMR who are likely to benefit from the procedure.

Methods. We performed an univariate logistic regression analysis of 20 factors on the benefits and outcomes of 134 patients who underwent isolated TMR at our institution between November 1994 and May 2000.

Results. Responders and nonresponders differed significantly with regard to the incidence of diabetes mellitus. For diabetic patients the chance of profiting from the TMR operation was only 43% of that of nondiabetic patients (odds ratio = 0.43 [0.20 to 0.92]). Furthermore, patients with a preoperative body mass index of less than 25 had a threefold increase in the probability of death during the first year after TMR as compared to patients whose body mass index was 25 or more (odds ratio = 2.97 [1.05 to 8.40]). The incidence of diabetes was also slightly but not significantly different between 1-year survivors and nonsurvivors.

Conclusions. In diabetic patients we recommend caution in selecting therapeutic TMR because outcomes are less satisfactory than in nondiabetics. Furthermore, patients with a body mass index below 25 have a significantly higher risk for death during the first postoperative year. Studies based on larger patient populations should follow.     

Inflammatory response and angiogenesis after percutaneous transmyocardial laser revascularization

BACKGROUND: The aim of our study was to investigate the inflammatory response immediately after percutaneous transmyocardial laser revascularization (PTMR) along with the underlying mechanism of angiogenesis. METHODS: Patients with angina pectoris underwent coronary angiography and were divided into two groups. Group A (n = 10) included patients with obstructed vessels who received PTMR, whereas group B (n = 5) comprised patients who had normal coronary arteries. Blood levels of neutrophils, procalcitonin, troponin-I, myoglobin, and creatine kinase (CK) mass were evaluated in each patient before angiography and monitored up to 48 hours after the procedure. Six patients were injected with 99mTc-leukoscan approximately 60 to 90 minutes after PTMR. During the 240 to 300 minutes after the radionuclide administration, single photon emission tomography (SPET) was performed and compared with conventional 99mTc-sestamibi-SPET. RESULTS: A significant increase in blood levels of neutrophils and procalcitonin was observed in group A only (p < 0.005). A slight but significant increase of troponin-I was evident in the same group (p < 0.05), and a distinct myocardial uptake of 99mTc-Leukoscan-SPET was observed in each patient along homologous regions treated by PTMR. CONCLUSIONS: The increased amount of neutrophils (both circulating and inside the treated myocardial areas) along with the raised levels of procalcitonin were the immediate reactions to PTMR. This systemic and intramyocardial inflammatory response is the underlying mechanism that gives rise to angiogenesis.     

激光心肌打孔血运重建术的临床应用

作者对７例不能作冠状动脉搭桥和经皮冠状动脉球囊扩张、并且药物治疗无效的冠心病心绞痛患者使用国产７００瓦ＣＯ２激光器作激光心肌打孔血运重建术。７例患者心肌打孔数目１６２个,平均２４个。手术时间１５０±３０分。１例于术后第３天因呼吸衰竭死亡,其余６例术后随访２～１２个月。随访包括心绞痛级别、用药情况及心功能,并在术后３、６和１２个月检查超声心动图和心肌ＳＰＥＣＴ。结果显示：４例心绞痛消失,２例明显缓解。２例于打孔后１～６个月作平板运动试验,运动时间比术前延长,４例做超声心动图示静息状态下室壁动度均有增加,１例在术后１２个月左室射血分数由术前的４２％提高到５４％;２例做超声心动图－多巴酚丁胺检查示多巴酚丁胺对心室壁动度的作用及心肌对多巴酚丁胺的最大耐受量均比术前增强;心肌ＳＰＥＣＴ示与术前比心肌打孔区的血液灌注明显增加。作者认为：本方法作为冠心病治疗的一种新方法,可有效地缓解心绞痛,改善心肌血液灌注,提高心脏功能。     

Ultrastructural and immunohistochemical analysis of early myocardial changes following transmyocardial laser revascularization

BACKGROUND AND AIM OF THE STUDY: Transmyocardial laser revascularization (TMR) has demonstrated significant relief in patients presenting with refractory angina. However, the mechanism by which TMR improves clinical symptoms is unclear. This study analyzes the early immunohistochemical and ultrastructural features of the human myocardium following TMR. METHODS: Specimens of myocardium that contained laser channels were removed in toto at autopsy from three male patients, ages 41, 57, and 65 (mean age 55.8) who had died 1 to 11 days (mean 6.8) following laser revascularization. Consecutive parallel sections of specimens were stained with cell-type specific antibodies to CD3 (to identify T-lymphocytes), CD68 (macrophages), Factor VIII (endothelial cells), and myosin (myocytes). Additionally, adjacent areas of myocardium that contained laser channels were processed and analyzed by transmission electron microscopy. RESULTS: The internal lining surface of laser channels was composed of vacuolized and condensed myocardial debris. No obvious connections were noted between laser channels and the ventricular cavity. No endothelialization of channels was observed, whereas the adjacent noninjured myocardium demonstrated microvessels lined by well-preserved endothelial cells. The laser channels were surrounded by zones of necrotic cardiomyocytes. CONCLUSIONS: Our observations suggest that laser channels are not lined by endothelial cells during the early stages following TMR. Mechanisms other than direct myocardial perfusion from the ventricular cavity by patent endothelialized channels may explain the immediate relief from angina provided by TMR.     

Angiogenesis three months after clinical transmyocardial laser revascularization using an excimer laser.

BACKGROUND AND OBJECTIVE: We present for the first time histologic findings 3 months after clinical transmyocardial laser revascularization using a XeCl excimer laser. STUDY DESIGN/MATERIALS AND METHODS: Histology was performed on a patient who died from a noncardiac cause 3 months post-excimer TMLR. RESULTS: In the treated myocardium, no patent channels were found but scars were seen with a linear distribution and in continuity with circumscribed small fibrotic endocardial and epicardial scars. The scars were highly vascularized by new vessels, ranging from small capillaries to large thin walled, and sometimes branching ectatic vessels. Sprouting of vessels into the adjacent myocardium was also observed. CONCLUSION: These results suggest that angiogenesis might play a role in the clinical improvement after TMLR.     

Neovascularization after transmyocardial laser revascularization in a model of chronic ischemia

Background. The mechanism of clinical improvement after transmyocardial laser revascularization (TMR) is unknown. One hypothesis holds that TMR causes increased myocardial perfusion through neovascularization. This study sought to determine whether angiogenesis occurs after TMR in a porcine model of chronic myocardial ischemia.

Methods. Six miniature pigs underwent subtotal left circumflex coronary artery occlusion to reduce resting blood flow to 10% of baseline. After 2 weeks in the low-flow state, dobutamine stress echocardiography and positron emission tomography were performed to document ischemic, viable myocardium. The animals then underwent TMR and were sacrificed 6 months later for histologic and immunohistochemical analysis.

Results. Histologic analysis of the lased left circumflex region demonstrated many hypocellular areas filled with connective tissue representing remnant TMR channels. Histochemical staining demonstrated a highly disorganized pattern of neovascularization consistent with angiogenesis located predominantly at the periphery of the channels. Immunohistochemical analysis confirmed the presence of endothelial cells within neovessels. Vascular density analysis revealed a mean of 29.2 ± 3.6 neovessels per high-power field in lased ischemic myocardium versus 4.0 ± 0.3 (p < 0.001) in nonlased ischemic myocardium.

Conclusions. This study provides evidence that neovascularization is present long term in regions of ischemic, viable myocardium after TMR. Angiogenesis may represent the mechanism of clinical improvement after TMR.     

采用新方法对激光心肌血运重建术机制的再认识

目的　比较传统激光心肌血运重建术 (T TMLR)与非透壁激光心肌血运重建术 (N TMLR)对心肌缺血面积、心肌坏死面积及血管新生的影响。　方法　 30只家兔急性心肌缺血模型 ,随机分为 3组 ,单纯心肌梗死组 (MI) ,MI加T TMLR组 (MI +T =TMLR) ,MI加N TMLR组 (MI +N -TMLR)。采用伊文蓝 氯化三苯基四唑 (TTC)双重染色法测定心肌缺血、坏死面积 ,并通过HE染色观察新生血管的密度。　结果　MI+T TMLR组和MI+N TMLR组心肌缺血面积分别为 (30 6± 1 0 ) %和 (30 2± 0 4) % ,均明显小于MI组 (37 2± 0 2 ) % ,差异有非常显著性意义 (F =2 1 0 4 ,P <0 0 1 ) ;MI+T TMLR组和MI+N TMLR组心肌坏死面积分别为 (1 7 0± 0 7) %和 (1 6 9± 0 6) % ,与MI组的(1 7 9± 0 5) %比较差异无显著性意义 (F =1 73 ,P >0 0 5) ;MI+T TMLR组和MI+N TMLR组血管新生平均分级分别为 1 8和 1 6 ,均明显大于MI组的 0 6 ,差异有非常显著性意义 (F =1 5 32 ,P <0 0 1 )。结论　MI+N TMLR可获得与MI+T TMLR相同的效果。通过激光孔道诱导血管新生并缩小心肌缺血面积可能是激光心肌血运重建术的主要作用机制之一 ,而激光孔道是否通畅与其作用机制无关。     

Operative technique for thoracoscopic transmyocardial laser revascularization

We describe herein the operative steps used to perform a transmyocardial laser revascularization by thoracoscopy. A special technique and specific equipment are required for the efficacy and safety of the procedure. Our preliminary results with this novel approach suggest that it could be a valid alternative to the thoracotomic procedure.     

Quality of life and survival after transmyocardial laser revascularization with the holmium:YAG laser

BACKGROUND: The purpose of this investigation was to assess postoperative survival and quality of life with transmyocardial laser revascularization (TMR) in high-risk patients. METHODS: During a 24-month period, 81 consecutive patients underwent either sole therapy TMR (n = 34) or TMR with coronary artery bypass grafting (n = 47) using a holmium:yttrium-aluminum-garnet (YAG) laser. Outcomes were assessed in three high-risk groups, including patients with left ventricular dysfunction (ejection fraction < or = 0.40) (n = 37), unstable angina (n = 30), and congestive heart failure (n = 33). Disease-specific quality of life was assessed using the Seattle Angina Questionnaire in 58 late survivors and compared with an age-matched cohort undergoing coronary artery bypass grafting only (no TMR) (n = 20). RESULTS: Overall mortality was 6% +/- 3% (+/- 70% confidence limit) and appeared higher with left ventricular dysfunction (11% +/- 5% vs 2% +/- 2%), but the difference did not reach statistical significance (p = 0.17; power = 0.16). There was also no statistical difference with unstable angina (10% +/- 6% vs 4% +/- 3%; p > 0.53) or congestive failure (9% +/- 5% vs 4% +/- 3%; p > 0.66). However, survival at 18 months was significantly lower with left ventricular dysfunction (62% +/- 9% vs 90% +/- 5%; p < 0.003) and congestive failure (48% +/- 10% vs 96% +/- 3%; p < 0.001). For sole therapy TMR, quality of life was diminished comparing TMR with coronary artery bypass grafting (p < 0.004) and coronary artery bypass grafting only (p < 0.002). CONCLUSIONS: Transmyocardial laser revascularization can be performed in high-risk patients, but survival is significantly impaired in patients with left ventricular dysfunction and congestive failure, and quality of life is diminished without some degree of direct revascularization.     

Survival after transmyocardial laser revascularization in relation to nonlasered perfused myocardial zones

BACKGROUND: Transmyocardial laser revascularization for severe diffuse coronary artery disease reduces angina significantly. The effect on survival, however, is questionable, and risk factors are not adequately addressed. Considering that transmyocardial laser revascularization channels do not remain patent for improving direct myocardial blood supply, other variables such as perfusion through open native or grafted vessels in remote non-transmyocardial laser revascularization areas are probably more important for survival. This hypothesis is the subject of the study. METHODS: Transmyocardial laser revascularization was performed with a CO2 laser system in 63 patients between October 1995 and December 1997. Patients received transmyocardial laser revascularization alone or in combination with coronary artery bypass grafting. The heart was divided into three perfusion zones as determined by the three major coronary arteries. Patients were divided into three groups according to the number of zones that were perfused by either a native coronary artery or a patent bypass graft: group 1 (n = 9), none; group 2 (n = 24), one; and group 3 (n = 30), two. Follow-up was performed at 3, 6, 12, 24, and 36 months and was 100% complete. Mean latest follow-up was 26.2 months, minimal follow-up of survivors was at least 12 months. RESULTS: Overall mortality was remarkably higher in group 1 (77.8%) compared with group 2 (20.8%, p = 0.005) and group 3 (13.3%, p = 0.001). Hospital mortality was 22.2% in group 1, 0% in group 2, and 3.3% in group 3. Late mortality was also higher in group 1 (55.5% versus 20.8%, and versus 9.9%, respectively). Cardiac deaths were more frequent in group 1 (55.5% versus 12.5% in group 2, p = 0.02, and versus 9.9% in group 3, p = 0.009). The number of perfused myocardial zones showed a significant influence for survival (p = 0.002). CONCLUSIONS: These data give some directional evidence that survival seems to be beneficially affected by the number of nonlasered perfused myocardial zones through native vessels or grafts in patients undergoing transmyocardial laser revascularization.     

Quantification of microembolic signals during transmyocardial laser revascularization

Transmyocardial laser revascularization (TMLR) is known to induce cerebral microembolic signals (MES). We quantified laser induced MES in patients undergoing TMLR during cardiopulmonary bypass for coronary artery bypass grafting (group A) and during TMLR treatment alone (group B). The total number of MES during a single laser application with identical energy was significantly higher in group A compared to group B (P<0.001). Also the peak of MES occurred significantly later in group A (P<0.0001). An increase of laser energy was associated with an increase in numbers of MES particular in group B (r=0.641). Different TMLR modalities generate different amounts of cerebral microembolic signals. Thus, adjustment of TMLR to these modalities may reduce potentially harmful cerebral microemboli and warrants further evaluation.     

Intraoperative arrhythmias and tissue damage during transmyocardial laser revascularization

BACKGROUND: Transmyocardial laser revascularization creates transmural channels to improve myocardial perfusion. Different laser sources and ablation modalities have been proposed for transmyocardial laser revascularization. We investigated the incidence of cardiac arrhythmias and laser-tissue interactions during transmyocardial laser revascularization of normal porcine myocardium with three different lasers. METHODS: We used a continuous-wave, chopped CO2 laser (20 J/pulse, 15 ms/pulse) synchronized with the R wave; a holmium:yttrium aluminum garnet (Ho:YAG) laser (2 J/pulse, 250 micros/pulse, 5 Hz); and a xenon-chloride (excimer, Xe:Cl) laser (35 mJ/pulse, 20 ns/pulse, 30 Hz). Each laser was used 30 times as the sole modality in four consecutive pigs, yielding 120 channels. RESULTS: The average number of pulses needed to create a channel was 1, 11 +/- 4, and 37 +/- 8 for the CO2, Ho:YAG, and Xe:Cl lasers, respectively. All Ho:YAG and Xe:Cl channels had premature ventricular contractions. Ventricular tachycardia occurred in 70% of the Xe:Cl and 60% of the Ho:YAG channels. Only 36% of the CO2 channels had premature ventricular contractions, and only 3% of the CO2 channels had ventricular tachycardia (p < 0.001 versus Ho:YAG and Xe:Cl). Ho:YAG channels were highly irregular: each had a 0.6-mm-wide central zone surrounded by a ring of coagulation necrosis (diameter, 1.84 +/- 0.67 mm) with effaced cellular architecture in a thin hemorrhagic zone. The Xe:Cl sections exhibited the same patterns on a smaller scale (diameter, 0.74 +/- 0.18 mm). The CO2 channels were straight and well demarcated. The zone of structural and thermal damage extended over half the channel's diameter, measuring 0.52 +/- 0.25 mm. CONCLUSIONS: During transmyocardial laser revascularization, the CO2 laser synchronized with the R wave is significantly less arrhythmogenic than the Ho:YAG and Xe:Cl lasers not synchronized with the R wave. In addition, the interaction of the CO2 laser with porcine cardiac tissue is significantly less traumatic than that of the Ho:YAG and the Xe:Cl lasers.