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。     

Minimally invasive techniques in orthopedic oncology: radiofrequency and laser thermal ablation

Image-guided percutaneous thermal ablation is a safe and effective method to reduce pain in patients with painful bone tumors. Computed tomography-guided radiofrequency or laser ablation is the modality of choice for most osteoid osteomas. Radiofrequency or laser thermal ablation also offers an alternative method for palliation of localized, painful osteolytic metastatic lesions. Pain can be reduced and neural damage prevented, improving the quality of life for patients with cancer who often have multimorbid conditions and limited life expectancy. A multidisciplinary approach that includes orthopedic surgeons, neurosurgeons, medical and radiation oncologists, and interventional radiologists is essential to manage these patients.     

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.     

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.     

Perioperative management of patients undergoing transmyocardial laser revascularization

Advanced revascularization strategies continue to uncover a growing number of patients with symptomatic diffuse coronary artery disease. Transmyocardial laser revascularization (TMR) provides significant benefit in terms of improved quality of life and more complete revascularization for these difficult to treat patients when TMR is used as sole therapy or in combination with coronary artery bypass grafting. The safe clinical application of this important procedure relies on diligent perioperative management with appropriate patient selection, intraoperative care that avoids myocardial ischemia, and postoperative pain control along with expeditious reinstitution of antianginal medications. The treatment paradigms learned with the safe application of TMR should prove useful as new therapies to extend our revascularization options are developed.     

Wall motion and perfusion analysis of transmyocardial laser revascularization

OBJECTIVE: Transmyocardial laser revascularization (TMLR) creates channels in the myocardium. The aim of the treatment is to relieve angina in patients with end-stage coronary artery disease. We studied the effect of TMLR on myocardial function and perfusion with the combination of cine magnetic resonance imaging (MRI) and thallium scintigraphy. DESIGN: Eight patients with severe triple-vessel coronary artery disease were studied with MRI and thallium scintigraphy before and 6 months after laser treatment. RESULTS: TMLR did not improve global left ventricular (LV) function or myocardial perfusion. However, systolic wall thickening deprived in segments with fixed perfusion defects in 6 months and laser treatment prevented this deprivation (p = 0.03). In addition single photon emission computed tomography (SPECT) imaging indicated that TMLR prevented conversion of reversible into fixed defects. CONCLUSION: In severe, progressing coronary artery disease TMLR does not improve global LV function or myocardial perfusion, but it preserves systolic wall thickening in fixed defects (scar). It also prevents changes from ischemic myocardial regions to scar.     

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.     

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.     

Experimental, morphological and clinical aspects of transmyocardial laser revascularization

Experimental, pathomorphological and clinical data substantiating use of transmyocardial laser revascularisation in the treatment of coronary heart disease (CHD) are presented. It is shown that the objective criterion of clinical efficacy of transmyocardial laser revascularisation in 58 patients with CHD is an increase of myocardial perfusion due to neoangiogenesis. This leads to improvement of cardiac function and general state of the patients. Surgical intervention has no substantial influence on contractile function of left ventricular myocardium in patients with CHD.     

Guidelines for the clinical use of transmyocardial laser revascularization

Patients with chronic, severe angina refractory to medical therapy who cannot be completely revascularized with either percutaneous catheter intervention or coronary artery bypass graft surgery (CABG) are clinically challenging. Transmyocardial laser revascularization (TMR), as sole therapy or as an adjunct to CABG, may be appropriate therapy for these patients. The recommendations are based on a review of the available evidence including expert consensus opinions. The author follows the format of the American Heart Association and the American College of Cardiology guidelines for diagnostic and therapeutic procedures. There are class I indications for sole therapy TMR and class IIA indications for TMR as an adjunct to CABG. TMR is indicated for selected patients: as sole therapy for a subset of patients with refractory angina. It also may be effective as an adjunct to CABG for a subset of patients with angina who cannot be completely revascularized surgically.     

The role of transmyocardial laser revascularization in congestive heart failure

Transmyocardial laser revascularization (TMLR) has been approved as an indirect coronary revascularization measure through angiogenesis around created channels in patients who are not amenable to direct revascularization methods such as coronary artery bypass grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA). TMLR is less invasive and there are no contraindications in terms of left ventricular function. Therefore all patients who have untreatable lesions by CABG or PTCA with reversible ischemia are candidates for TMLR therapy. In a Japanese clinical trial, improvement of left ventricular function associated with relief of persistent angina and improved perfusion was seen in 54% of patients. Significant reduction of operative risk in adjunctive TMLR (combination of TMLR with CABG) compared with isolated CABG has been also demonstrated in a randomized trial. These results indicate the usefulness of adjunctive TMLR in multivessel-disease patients with left ventricular dysfunction. Because TMLR is a simple and less-invasive technique, combined use of TMLR with off-pump CABG or MIDCAB is also an attractive revascularization strategy in ischemic cardiomyopathy patients.     

Functional comparison of transmyocardial revascularization by mechanical and laser means

Background. As a result of the clinical benefit observed in angina patients treated by transmyocardial revascularization (TMR) with a laser, interest in mechanical TMR has been renewed. Although the injury induced by mechanical TMR is similar to laser TMR, the resultant impact on myocardial contractility is unknown. The purpose of this study was to determine whether mechanical TMR improves ventricular function as compared with laser TMR in chronically ischemic myocardium.

Methods. After establishing an area of chronic myocardial ischemia, 25 domestic pigs were randomized to treatment by: excimer laser (group I), a hot needle (50°C) (group II), a normothermic needle (group III), an ultrasonic needle (40 KHz) (group IV), or no treatment (group V). All devices create a transmural channel of the same diameter; 22 ± 1 transmural channels were created in each animal. Regional myocardial contractility was assessed by measuring ventricular wall thickening at rest and with dobutamine stress echocardiography. Six weeks after revascularization, the animals were restudied at rest and with stress. Postsacrifice and histologic analysis of angiogenesis and TMR effects was then assessed.

Results. Laser TMR provided significant recovery of ischemic myocardial function. This improvement in contractility after laser TMR was a 75% increase over the baseline function of the ischemic zone (p < 0.01). Mechanical TMR provided no significant improvement in function posttreatment. In fact, TMR achieved with an ultrasonic needle demonstrated a 40% worsening of the contractility versus the pretreatment baseline (p < 0.05). Histologic analysis demonstrated a significant increase in new blood vessels in the ischemic zone after laser TMR, which was not demonstrated for any of the other groups (p < 0.05). Additionally, evaluation of the mechanical TMR channels demonstrated significant scarring, which correlated with the functional results.

Conclusions. Using devices to create an injury analogous to the laser, mechanical TMR failed to improve the function of chronically ischemic myocardium. Only laser TMR significantly improved myocardial function.     

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.     

Holmium: YAG laser transmyocardial revascularization relieves angina and improves functional status

Background. Transmyocardial revascularization (TMR) surgery uses laser channeling of diseased myocardium to treat ischemia and angina. Rigorous prospective randomized studies have been previously unavailable.

Methods. Forty-three patients were randomized to a medication group and 43 to a group scheduled for TMR surgery and medication. All had advanced cardiac ischemia with CCSA class 3 or 4 angina, took at least 2 cardiac medications at maximum doses, and were ineligible for angioplasty or bypass.

Results. Forty-two of 43 TMR group patients received surgery and were discharged after hospitalizations averaging 3.2 days. Two suffered perioperative MIs, with one death. Four others died within 12 months of surgery, 3 from cardiac events and 1 from pneumonia. Five medical group patients died from cardiac events within 12 months. Three, 6, and 12 month exams showed angina class improvement in TMR patients compared to preoperative values (3.86 ± 0.05 vs 1.71 ± 0.2 P < 0.0001), and to controls at 12 months (3.77 ± 0.07 vs 1.71 ± 0.2, P < 0.0001). Exercise tolerance improved in TMR patients over preoperative values, and was better than medication group scores after 12 months (490 ± 17 sec. vs 294 ± 12 sec., p = 0.0002).

Conclusions. Holmium:YAG laser channeling of the myocardium improves function and reduces angina in advanced cardiac patients who lack alternative therapeutic options.     

The Society of Thoracic Surgeons practice guideline series: transmyocardial laser revascularization

BACKGROUND: Patients with chronic severe angina refractory to medical therapy who cannot be completely revascularized with either percutaneous catheter intervention or coronary artery bypass graft surgery present clinical challenges. Transmyocardial laser revascularization, either as sole therapy or as an adjunct to coronary artery bypass graft surgery, may be appropriate for some of these patients. Although transmyocardial revascularization has consistently been demonstrated as an efficacious means of relieving angina, the mechanism of its effects are still debated, and criteria for the selection of patients for this novel therapy have not been adequately defined. METHODS: We reviewed the available evidence to allow us to make recommendations for the appropriate therapeutic applications of transmyocardial revascularization following the format of the American Heart Association and the American College of Cardiology guidelines for diagnostic and therapeutic procedures. Our recommendations were classified as class I, IIA, IIB, or III. For each recommendation we defined the level of supporting evidence as A, B, or C. RESULTS: We identified class I indications for transmyocardial revascularization as sole therapy and class IIA indications for transmyocardial revascularization as an adjunct to coronary artery bypass graft surgery with levels of evidence A and B, respectively. CONCLUSIONS: Transmyocardial laser revascularization may be an acceptable form of therapy for selected patients: as sole therapy for a subset of patients with refractory angina and as an adjunct to coronary artery bypass graft surgery for a subset of patients with angina who cannot be completely revascularized surgically.     

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.