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.     

Efficacy of transmyocardial laser revascularization and thoracic sympathectomy for the treatment of refractory angina

Background

Transmyocardial laser revascularization (TMR) is an effective treatment for relief of refractory angina. This benefit may be mediated by increase in myocardial perfusion or by cardiac denervation. We investigate the efficacy of TMR and thoracic sympathectomy (TS) for relief of angina and whether any clinical benefit is associated with enhanced myocardial perfusion.

Methods

Twenty consecutive patients with nonrevascularizable coronary arteries and intractable angina were prospectively randomized to have TMR by holmium: yttrium aluminum garnet laser or TS. Subjects were clinically evaluated before, and for 42 months after, surgery. They underwent exercise tolerance testing and rest and stress quantitative perfusion magnetic resonance imaging (MRI) before, and 6 months after surgery.

Results

The demographics of the two groups were similar. There was no perioperative mortality; however, two patients died in the TS group during follow-up. The Canadian Cardiovascular Society angina score improved from 3.4 ± 0.5 to 2.6 ± 1.1 (p = 0.06) in the TS group at 6 months but returned to 3.2 ± 0.7 at 42 months, while in the TMR group it improved from 3.6 ± 0.5 to 1.9 ± 0.7 (p = 0.008) at 6 months and deteriorated to 2.5 ± 0.9 (p = 0.01) after 42 months of surgery. The TMR-treated patients showed significant improvements in the SF-36 scores and Seattle Angina Questionnaire only at 6 months, whereas TS-treated patients did not show amelioration at any time during follow-up. The MRI protocol was completed in 15 of 20 (TMR = 8; TS = 7) patients and no significant differences in qualitative or quantitative perfusion variables were demonstrated in either group.

Conclusions

A greater clinical benefit was obtained with TMR than with TS early after surgery but this clinical effect did not seem to be associated with improvement in myocardial perfusion as assessed by MRI and part of the beneficial effect was lost by 42 months after surgery.     

A UK trial-based cost--utility analysis of transmyocardial laser revascularization compared to continued medical therapy for treatment of refractory angina pectoris.

OBJECTIVE: Transmyocardial laser revascularization (TMLR) is used to treat patients with refractory angina considered unsuitable for conventional forms of revascularization. Using patient specific data from a single centre UK randomised-controlled trial, we aimed to determine whether, from a UK National Health Service (NHS) perspective, TMLR plus standard medical management is cost-effective when compared with standard medical management alone. METHODS: One hundred and eighty-eight patients assessed as having refractory angina, and not suitable for conventional forms of revascularization were randomized to receive TMLR and medical management (94) or medical management alone (94). Costs to the UK NHS of TMLR (where appropriate), and all secondary sector health care contacts and cardiac-related medication in the 12 months following randomization, were collected. Patient utility as measured using the EuroQol EQ-5D questionnaire was combined with 12-month survival data to generate quality adjusted life years (QALYs). RESULTS: The mean cost per patient over the year from hospitalization for TMLR was 11,470 pounds sterling and for medical management alone was 2586 pounds sterling, giving a cost difference of 8901 pounds sterling (95% confidence interval (CI) 7502 pounds sterling--10,008 pounds sterling: P < 0.0001). The mean QALY difference, in favour of TMLR was 0.039 (95% CI -0.033 to 0.113: P = 0.268). This gives an incremental cost per QALY of over 228,000 pounds sterling. Analysis of stochastic uncertainty and of sensitivity to gross changes in key parameters consistently produces very high costs per QALY. CONCLUSIONS: The policy implications are clear: for such patients TMLR is an inefficient use of UK health service resources. This conclusion would not be changed by considerable improvements in effectiveness or reductions in cost.     

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.     

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.     

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。     

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。     

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-microm 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.     

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.     

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.     

Failure of chronic transmyocardial laser revascularization to alter cardiac nociceptive reflexes: implications for the treatment of angina pectoris

The aim of this study was to assess the delayed effects of transmyocardial laser revascularization (TMLR) on cardiac nociceptors. Experiments were performed in anesthetized dogs 1 month after thoracotomy with either TMLR (n = 17) or sham laser procedure (n = 17). All dogs underwent sinoaortic denervation and vagotomy to isolate the sympathetic afferent system. Left ventricular sympathetic afferents were stimulated by intracoronary bradykinin and transmural myocardial ischemia. Efferent responses were measured by direct recording of renal sympathetic nerve activity. Renal nerve responses to intracoronary bradykinin administered to the laser-treated anterior ventricular wall were not significantly different from those observed from the unlased posterior wall. Anterior transmural ischemia elicited similar renal nerve responses in laser-treated and sham groups. Pathologic analysis showed intact neural structures in the subepicardial regions both near and remote from the lased channels. We conclude that reflexes mediated by left ventricular sympathetic afferents are preserved after chronic TMLR. These findings do not support the neural hypothesis for angina relief.     

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.