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.     

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.     

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。     

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.     

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.     

Cell therapy plus transmyocardial laser revascularization for refractory angina

We describe the use of autologous bone marrow cells combined with transmyocardial laser revascularization in a 74-year-old man with refractory angina. Baseline cardiac magnetic resonance imaging revealed a markedly depressed left ventricle systolic function and an extensive area of myocardial ischemia. During surgery, 11 laser shots using a CO2 Heart Laser System (PLC Medical Systems, Milford, MA) were fired and a 5-mL cell suspension containing 21.5 x 10(6) bone marrow cells/mL was delivered by multiple injections into the myocardium. At 6 months after the procedure, another cardiac magnetic resonance imaging showed an almost complete resolution of the perfusion defect and an improvement in left ventricular contractility.     

Strategies for the reduction of cerebral microembolism during transmyocardial laser revascularization

BACKGROUND AND OBJECTIVES: During transmyocardial laser revascularization (TMLR), multiple microembolic signals (MES) can be detected in cerebral arteries. We sought to characterize composition and clinical relevance of these MES and to evaluate strategies to reduce cerebral microembolization during TMLR. STUDY DESIGN/MATERIALS AND METHODS: TMLR was performed in pigs. Laser energy was set to 4-10 J (group A) or 80 J (group B). Oxygen concentration was varied between 21 and 100%. MES were recorded in the ophthalmic artery. Brain and spinal cord were investigated histologically after 10 days. RESULTS: More MES could be detected during high- compared to low-energy laser procedures. Ventilation with 100% oxygen reduced the number of MES. No lesions were found on histology. CONCLUSIONS: The number of MES depends on the laser energy. Laser-induces cavitation-effects lead to an additional release of nitrogen bubbles. Thus, the microembolic load can be reduced by ventilation with 100% oxygen and by decreasing the laser energy.     

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.     

Damage to pulmonary artery catheter during transmyocardial laser revascularization

This case report describes damage to a pulmonary artery catheter (PAC) during transmyocardial laser revascularization. We observed persistent bleeding and a temperature reading of "too high" from the temperature connection port of PAC during cardiopulmonary bypass while the patient's nasopharyngeal temperature read 34 degrees C. This alerted us to the possibility of PAC damage during creation of laser channels in the right coronary artery territory on the inferior surface of the heart. This is a unique complication related to this coronary revascularization procedure. IMPLICATIONS: We report an unusual case of pulmonary artery catheter (PAC) damage during transmyocardial laser revascularization (TMLR). This observation should alert the anesthesiologist to the fact that the PAC may be damaged when TMLR is performed on the right side of the heart. We recommend that the PAC be withdrawn during this procedure.     

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.