Transmyocardial laser revascularization

Transmyocardial laser revascularization (TMR) is a procedure that is in a state of transition. The purpose of this article is to review the historical aspects of TMR. Important nursing aspects of the thoracotomy and percutaneous approaches are detailed. Outcomes related to the surgical procedure are also discussed. Although the exact mechanism of TMR is unknown, the procedure offers an improvement in the quality of life, reduction in antianginal medications, increased exercise tolerance, and a possibility of prolonged life.     

Transmyocardial laser revascularization.

In transmyocardial laser revascularization, a small left thoracotomy incision is made at the fifth rib. The surgeon dissects until adequate exposure of the heart is made, and the laser can be used. The areas to be lasered are identified, and treatment begins. As each laser beam penetrates the myocardium, a flash of bubbles can be seen on echocardiogram exiting the left ventricular outflow tract, which confirms adequate channeling. After revascularization, the mitral valve is inspected for any damage to papillary muscle or leaflets. This case report focuses on a new laser procedure that creates channels in the heart that promote angiogenesis and reestablish blood flow. A 47-year-old man presented for this surgery after having previous coronary artery bypass surgery. He had worsening angina and was not recommended for repeat bypass surgery because of his diffuse disease. Transmyocardial laser revascularization was offered as an alternative to medical therapy. Complications reported include dysrhythmia, bleeding, congestive heart failure, mitral valve damage, low cardiac output syndrome, and death. Many patients note substantial anginal relief after a few weeks. Transmyocardial laser revascularization gives an alternative to those with intractable angina and generally offers an improvement in quality of life.     

Transmyocardial laser revascularization: overview of clinical and experimental data]

Transmyocardial laser revascularization (TMLR) using carbon dioxide and Holmium YAG laser has been approved by FDA and is now under clinical evaluation in patients with refractory angina who are not candidate of CABG or PTCA. Original concept of TMLR was direct perfusion from left ventricle through channel created by laser. However, pathological analysis showed closed channel in almost all cases, and most possible mechanism of TMLR are now thought to be angiogenesis following to inflammatory response of laser injury. Most prospective randomized trial comparing TMLR and conservative medical treatment demonstrated significantly less angina in TMLR patients and better exercise tolerance and angina-free survival rate during follow-up period. On the other hand, no significant differences were demonstrated in overall mortality rate, myocardial perfusion or cardiac function.     

Transmyocardial revascularization: peril and potential

Transmyocardial laser revascularization is a technique for the treatment of patients with chronic angina pectoris that is refractory to medical therapy and who are not eligible for surgical intervention. Percutaneous myocardial revascularization is a less-invasive catheter-based procedure that has been adapted from transmyocardial laser revascularization. Six prospective randomized clinical trials have been performed with transmyocardial laser revascularization and 5 have been performed using percutaneous myocardial revascularization. All of the transmyocardial laser revascularization and 4 of the percutaneous myocardial revascularization studies showed a significant improvement in angina class; however, results for improved survival, increased exercise tolerance, improved ejection fraction, and improved myocardial perfusion were less definitive. Transmyocardial laser revascularization has significant potential for morbidity and mortality. This article summarizes the results of the randomized trials, explains the current theories for the mechanism of transmyocardial laser revascularization, and discusses its current role in treatment for patients, considering the evidence that currently exists.     

Transmyocardial laser revascularization: epicardial ECG detection provides efficient R-wave triggering during mobilization of the heart

OBJECTIVE: In order to achieve an accurate intraoperative ECG detection, a new technique in detecting the trigger-signal was developed. In contrast to the traditional three-lead ECG-configuration, the left leg electrode was connected to a transient epicardial pacemaker electrode on the left-ventricular surface. BACKGROUND DATA: The Holmium:YAG-Laser for Transmyocardial Laser Revascularization (TMLR) is R-wave-triggered, providing the release of energy only during the refractory period of the heart cycle. However, an exact ECG-triggering during mobilization of the apex and/or posterior wall is difficult to achieve by using conventional ECG-configuration, therefore increasing the risk for mistriggering and induction of arrhythmias during TMLR. MATERIALS AND METHODS: Two groups of patients, all undergoing stand alone TMLR-procedures via left minithoracotomy, were compared. Ten patients were operated with the conventional ECG configuration (group 1) and ten patients with the modified epicardial ECG configuration (group 2). RESULTS: In patients of group 1, as a result of a loss of the trigger signal or due to the triggering of artifacts, the incidence of correctly triggered QRS-complexes was 56% of all documented QRS-complexes. In contrast, an excellent triggering was observed in 98% (p < 0.001) in group 2, resulting in a reduction of laser operative time by 35% (p < 0.001) and a decrease in the incidence of intraoperative ventricular fibrillation (0 vs. 3). CONCLUSION: In conclusion, this new ECG configuration is a simple but effective method in achieving an excellent ECG signal during all stages of TMLR. As a consequence, a reduction in operative time and incidence of ventricular fibrillation can be achieved.     

高压喷射心肌打孔及孔道内填充温敏型壳聚糖水凝胶对孔道的影响

背景:大量研究表明透室壁性心肌血管重建能有效治疗难治性心绞痛和终末期冠心病,但心肌血运重建后透室壁性心肌孔道不能保持长时间通畅,容易闭合,从而限制了该技术的应用。目的:认识高压喷射心肌打孔联合孔道内填充温敏型壳聚糖水凝胶对孔道的影响,以及该治疗方法对急性心肌梗死犬的血管新生及心肌的保护作用。方法:将Injex无针注射器经适当改造后制作成高压喷射系统;由壳聚糖盐酸盐、β-甘油磷酸钠和羟基乙基纤维素按照一定的浓度比配制成温敏型壳聚糖水凝胶。健康杂种犬24只随机均分为3组:①单纯心肌梗死组制模成功后直接关胸。②心肌打孔+水凝胶组将壳聚糖水凝胶于结扎线以下左室前壁行高压喷射透壁性心肌打孔8~10个(1孔/cm2)。③心肌打孔组用等体积生理盐水于相同部位行心肌打孔。6周后行血流动力学检测,计算微血管密度和心肌梗死面积,行苏木精-伊红染色观察孔道通畅情况,天狼猩红染色检测胶原增生情况并计算Ⅰ、Ⅲ型胶原比值。结果与结论:①术后6周,心肌打孔组孔道明显缩小,部分节段已完全闭塞;心肌打孔+水凝胶组孔道仍未闭塞,开放直径100~300μm,部分节段已内皮化。②与单纯心肌梗死组比较,心肌打孔组和心肌打孔+水凝胶组促进了梗死区血管新...     

Holmium laser coronary thrombolysis--a new treatment modality for revascularization in acute myocardial infarction: review

Thrombolytic therapy has changed the approach to management of acute myocardial infarction (AMI). Although its therapeutic benefit has been well established, only about one-third of AMI patients receive lytics. In AMI patients for whom thrombolytics fail to achieve revascularization or for whom lytics are contraindicated, percutaneous transluminal coronary balloon angioplasty (PTCA) can be utilized. However, in a clinical setting of AMI PTCA is less successful and is associated with a higher complication rate than with PTCA for angina alone. This review details a novel application of laser angioplasty; in patients with AMI complicated by continuous chest pain and ischemia, a mid-infrared (2.1 micron) solid-state, pulsed-wave Holmium:YAG coronary laser (Eclipse, Palo Alto, CA) can be utilized for coronary thrombolysis and plaque ablation. In each patient the laser was applied after failure of a thrombolytic agent or when thrombolytics were contraindicated. We have gained experience with 13 lesions, 12 in a coronary artery and 1 in a vein graft. In each case a multifiber with laser catheter (1.4, 1.5, 1.7 or 2.0 mm) was advanced over a guide wire, emitting 250-600 mj/pulse at 5 Hz, followed by adjunctive PTCA. Clinical success (defined as less than or equal to 50% residual stenosis, adequate thrombolysis, no complications [including death, CVA, CABGs, dissection, perforation]) was achieved in all patients. All patients improved clinically, survived the AMI, and were discharged. This initial clinical experience demonstrates the feasibility and safety of Holmium:YAG coronary laser angioplasty in revascularization during AMI.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transmyocardial and percutaneous myocardial revascularization: current and future role in the treatment of coronary artery disease.

Transmyocardial revascularization (TMR) is a new treatment modality under evaluation in patients with severely symptomatic, diffuse coronary artery disease, in whom the potential for medical or interventional management has been exhausted. Preliminary clinical trials show improved ischemic symptoms within the first 3 months in about 70% of TMR-treated patients. The original proposed mechanism of surgical or catheter-based TMR (percutaneous myocardial revascularization [PMR]) was that channels mediate direct blood flow between the left ventricular cavity and ischemic myocardium. However, several alternative explanations for the clinical success of TMR have recently been suggested, including improved perfusion by angiogenesis, an anesthetic effect by nerve destruction, and a potential placebo effect. This article reviews the clinical role of TMR/PMR, its possible pathophysiologic mechanisms, and its controversies. It provides an overview of the actual scientific and clinical status of TMR and details future directions.     

Low-intensity laser therapy: a review.

Low-intensity laser radiation is characterized by its ability to induce athermic, nondestructive photobiological processes. Although it has been in use for more than 30 years, this phototherapy is still not an established therapeutic modality. We have summarized the main arguments being brought up against the use of this therapy and have reviewed the literature addressing both its in vitro and in vivo effects. We conclude that low-intensity laser irradiations might be of benefit in selected indications if the existing preliminary data can be confirmed by more prospective and well-controlled studies.     

Noninvasive revascularization by enhanced external counterpulsation: a case study and literature review

Nearly 8 million people in the United States suffer from symptoms of coronary artery disease (CAD). Unfortunately, the population of patients with ischemic coronary disease that is not readily amenable to surgical or percutaneous revascularization continues to grow. For patients who are not candidates for standard revascularization procedures and in whom aggressive medical therapy fails to control symptoms, enhanced external counterpulsation (EECP) is a new, noninvasive outpatient method to improve quality of life by decreasing ischemic symptoms and permit increased activity. We report the case of a 56-year-old woman with severe, symptomatic CAD receiving maximal medical therapy who underwent a course of EECP therapy because she was not a good candidate for other forms of revascularization. She demonstrated dramatic improvement in her anginal symptoms and complete resolution of myocardial ischemia on repeat nuclear stress imaging. This case suggests that EECP is a safe and effective method for reducing symptoms of myocardial ischemia in patients for whom standard percutaneous or surgical revascularization is not suitable treatment.     

Clinical and histological evaluation of laser myocardial revascularization

Studies exploring methods to revascularize the ischemic myocardium through increasing the collateral circulation were conducted by many investigators before the advent of myocardial revascularization by aortocoronary bypass grafting. Present alternatives, including surgical intervention, balloon angioplasty, thrombolytic therapy, and medical management, are the treatment of choice for the majority of patients. There are, however, a number of patients who do not respond to conventional management strategies. A clinical protocol was designed to assess the efficacy of transmural revascularization by creating CO2 laser channels in the ischemic areas of the left ventricle. Channels were made from the epicardial surface of the heart, through the ventricle, to the endocardium. Patients entered in the study were candidates for bypass grafting, but because of the pathology of the coronary artery system, bypass grafting alone would have resulted in incomplete revascularization. Postoperative thallium stress tests and left ventriculography indicate that channels have remained patent and that they perfuse the myocardium. Myocardial revascularization by laser channels may offer a viable adjunct in the treatment of ischemic heart disease.     

New options for untreatable coronary artery disease: angiogenesis and laser revascularization

Some patients with severe symptomatic coronary artery disease despite maximal medical therapy are not eligible for bypass surgery or percutaneous coronary intervention, but may be eligible for two newer therapies: therapeutic angiogenesis with growth factors and transmyocardial laser revascularization.     

Transmyocardial voyage of a temporary epicardial lead: an unusual long-term complication

Although the majority of temporary epicardial leads used during cardiac surgery are removed in the perioperative period, occasionally, the wires are cut and allowed to retract into the subcutaneous tissue. Complications arising from such retained epicardial wires are rare. We present a case of transmyocardial migration of a retained epicardial wire through the right ventricular myocardium into the pulmonary artery in a patient who had undergone coronary artery bypass graft surgery 13 years ago. We describe the presentation and successful management of this case.     

Transmyocardial Laser Revascularization revisited

Transmyocardial Revascularzation (TMR) is a relatively new surgical procedure used to treat angina that persists, despite other interventions (i.e. angioplasty, stenting or coronary artery bypass surgery). TMR is accomplished via an incision that exposes the heart muscle and permits application of the laser hand piece that creates new channels in the myocardium, thus improving myocardial perfusion and oxygen supply to the left ventricle. This article will explain the procedure, review patient selection criteria and discuss the nursing care for the TMR patient.     

Improved neoangiogenesis in transmyocardial laser revascularization combined with angiogenic adjunct in a pig model

Recent research has revealed neoangiogenesis as a basic phenomenon in transmyocardial laser revascularization (TMLR). Theoretically, myocardial neoangiogenesis could be further enhanced by the addition of angiogenic growth factors. Triads of TMLR channels were created in the lateral wall of the left ventricles of 12 pigs (mean body weight 73+/-5 kg), using a holmium:yttrium-aluminium garnet (YAG) laser. The animals were allocated randomly either to receive an injection of 100 microg of a bovine bone-derived growth factor mixture within the triads (n=6), or to a control group (n=6). Animals were killed 1 month later. Capillary and arteriolar densities were determined by computed morphometric analysis of histological sections of the triads. The capillary density of myocardial areas within the triads was significantly greater in the group receiving the bovine bone-derived growth factor mixture than in the control group (14.3+/-3.5/mm(2) and 5.7+/-1.4/mm(2) respectively; P<0.001). The difference was also significant when considering arteriolar density (0.7+/-0.4/mm(2) and 0.2+/-0.1/mm(2) respectively; P<0.001). For comparison, capillary and arteriolar densities of the TMLR channel scars were 48.7+/-9.7 and 1.9+/-0. 5/mm(2) respectively in the angiogenic group, and 46.3+/-13.7 and 2. 3+/-1.3/mm(2) respectively in the control group (no significant differences). These results demonstrate that the addition of angiogenic factors to TMLR stimulates neoangiogenesis significantly in the areas adjacent to the channels, but not within the channel scars. The latter are themselves strongly vascularized. Hence this combined approach, potentiating the effect of TMLR by establishing vascular connections between the neovessels of the channel scars, has the potential for improved clinical outcome.     

经食管超声心动图在激光心肌血运重建术中的应用

目的　探讨经食管超声心动图 (TEE)在激光心肌血运重建术 (TMLR)中监测的应用价值。方法静脉全麻后 ,插入经食管超声探头 ,打孔前再次观察室壁厚度及运动情况 ,测定左室射血分数 (LVEF) ,为调节激光打孔能量及打孔部位提供参考依据。打孔时建立好长轴四腔观图像 ,当孔道穿通时可监测到左室腔内微小气泡产生 ,同时观察心内结构有无损伤。结果　全组 3 4例冠心病患者共打孔 10 67个 ,穿通 10 3 1个 ,通畅率96.6% ,均未见心内结构损伤。结论　TMLR术中常规应用TEE监测 ,对指导激光打孔部位及调节激光能量具有重要价值。     

Medical therapy in the era of percutaneous coronary revascularization: A critical review

Percutaneous coronary revascularization (PCR) frequently results in relief of angina in patients with ischemic heart disease. The aim of this review is to put in perspective the role of PCR in the treatment of patients with coronary artery disease.     

激光心肌血运重建术治疗冠心病病人的护理

报道36例激光心肌血运重建术病人的术前术后护理。通过术前的心理、生活、用药护理,术后密切观察生命体征,持续心电监护,对抗凝、预防疼痛和感染、术后活动、饮食等进行细致观察和护理,认为良好的护理是促进病人康复的重要环节。