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Ann Thorac Surg 1998;65:700-704
© 1998 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Early Results of Transmyocardial Revascularization With a Holmium Laser

Department of Cardiac Surgery, University of Pisa Medical School, Pisa, Italy
Department of Cardiology, University of Pisa Medical School, Pisa, Italy
Department of Nuclear Medicine, University of Pisa Medical School, Pisa, Italy

Accepted for publication September 8, 1997.

Dr Bortolotti, UO Cardiochirurgia, Ospedale Cisanello, Via Paradisa 2, 56122 Pisa, Italy.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Background. Transmyocardial laser revascularization (TMLR), a surgical technique designed to improve perfusion in the ischemic myocardium by creating transmural channels, has been performed thus far using a carbon dioxide laser, with apparently gratifying early results. We have investigated clinically TMLR using a holmium laser as sole therapy for patients with coronary artery disease that is not amenable to traditional treatment such as coronary artery bypass grafting or percutaneous transluminal coronary angioplasty.

Methods. From November 1995 to December 1996, 16 patients underwent TMLR using a holmium laser. Their mean age was 68 ± 6 years and 75% were men. Previous coronary artery bypass grafting or percutaneous transluminal coronary angioplasty had been performed in 81% and 31% of the patients, respectively. Before operation, their mean anginal class was 3.4 ± 0.5 and their mean left ventricular ejection fraction was 0.49 ± 0.06. Six patients had unstable angina.

Results. There were no operative deaths. The mean duration of TMLR was 27 ± 13 minutes and the mean duration of the entire operation was 120 ± 40 minutes. There were no major postoperative complications and the mean hospital stay was 8 ± 4 days. There were 2 late deaths, 1 that occurred 40 days after TMLR as a result of stroke and 1 that occurred 4 months after TMLR as a result of myocardial infarction. Current survivors have been followed up for a mean of 10 ± 4 months (range, 3 to 15 months), with 7 patients followed up for 1 year. At last follow-up, the mean anginal class had decreased to 1.8 ± 0.7 (p = 0.001) and the patients had increased exercise tolerance and a reduced number of hospitalizations. However, no statistically significant changes in the percentage of segments with fixed or reversible ischemia and no statistically significant differences in the viability scores of lased and nonlased segments were observed.

Conclusions. Transmyocardial laser revascularization using a holmium laser is a simple technique with low operative risk and low morbidity. Early results confirm that clinical improvement is obtained in most patients, although significant changes in myocardial perfusion are not evident in the short term.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Transmyocardial laser revascularization (TMLR) is a technique designed to improve myocardial perfusion in patients with ischemic heart disease that is refractory to medical treatment and not amenable to traditional myocardial revascularization procedures [1]. In TMLR, improvement of blood flow should occur from the left ventricular cavity to the underperfused myocardium through transmyocardial channels created with a laser [2]. Transmyocardial laser revascularization so far has been performed using a carbon dioxide (CO₂) laser, and the initial results have been considered satisfactory [3][4][5][6]. We began performing TMLR clinically using a holmium laser at our institution in November 1995. We report our preliminary experience with TMLR using a holmium laser as sole therapy for symptomatic patients with coronary artery anatomy that is unsuitable for percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG).

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Patient Population
In November 1995, we began a clinical trial using a holmium:yttrium-aluminum garnet laser (Eclipse Surgi-cal Technologies, Inc, Sunnyvale, CA) after the study had been reviewed and approved by the ethical committee of our hospital and informed consent had been obtained from each patient.

The criteria used for patient inclusion were as follows: (1) the presence of angina despite maximal medical treatment; (2) evidence of coronary artery disease not suitable for PTCA or CABG because of diffuse disease, small vessels, or inadequate distal runoff (Fig 1); (3) documentation of myocardial ischemia and viability by scintigraphic studies; (4) a left ventricular ejection fraction of less than 0.30; and (5) absence of major contraindications to surgical procedures.

View larger version (144K): [in this window] [in a new window]   Coronary angiogram of a 67-year-old woman in whom all previous saphenous vein grafts had occluded and there was no evidence of native coronary arteries suitable for grafting.

View larger version (11K): [in this window] [in a new window]   Change in anginal class after transmyocardial laser revascularization.

Characteristics of the Eclipse Laser
The Eclipse laser system (Eclipse Surgical Technologies, Inc) is powered by a permanent, solid-state holmium:yttrium-aluminum garnet crystal lasing medium that operates at a wavelength of 2.1 µm in the mid-infrared spectrum. It delivers 5 pulses per second, with a pulse length of 250 microseconds. The laser beam is conducted through a flexible, lightweight optical fiber that allows the creation of 1-mm myocardial channels and does not require electrocardiographic synchronization.

Compared with the CO₂ laser, the holmium laser has a higher power density but a shorter tissue interaction time, resulting in a greater photoablative effect on tissues and lesser thermal effects [7].

Surgical Technique
The patients were intubated with a single-lumen catheter and monitored in a routine fashion. The operation was performed through a limited anterolateral thoracotomy incision made in the bed of the fifth rib and without the aid of cardiopulmonary bypass. Alternatively, TMLR can be performed through a thoracoscopic approach, as it was in 1 of the patients in this series. The pericardium was opened anterior to the phrenic nerve and suspended. Any previous CABG adhesions were dissected, exposing the left ventricular surface for treatment. Major epicardial coronary vessels were identified, as well as previous venous or arterial grafts.

Transmyocardial channels were created from the epicardium to the endocardium into the left ventricular cavity, mainly in ischemic areas identified before operation. However, the procedure almost always was extended to contiguous areas for more widespread treatment (Fig 3). The channels were distributed at a rate of about 1 per square centimeter, with approximately 40 channels drilled for each patient. Penetration of the fiberoptic laser probe into the left ventricular chamber can be felt easily by the surgeon and also is indicated by a variation in the acoustic patterns. For this reason, echocardiographic visualization is not required. Nevertheless, intraoperative transesophageal echocardiography was performed routinely to confirm the creation of a complete channel and to rule out accidental injury to the mitral valve apparatus. Bleeding from the channel was controlled easily by digital compression, and epicardial sutures almost never were required.

View larger version (1K): [in this window] [in a new window]   Intraoperative view of the left ventricle approached through a limited left anterolateral thoracotomy and the optical fiber used to deliver the holmium laser beam.

Data Collection and Statistical Analysis
Direct patient reevaluation was performed at 3, 6, and 12 months after the procedure to collect data on anginal class, functional class, and number of hospitalizations after TMLR. At these same intervals, echocardiographic evaluation, stress testing by cycle ergometer, and ²⁰¹Tl-SPECT also were scheduled. Preoperative and postoperative scans were reviewed to assess any change in the number of segments with fixed and reversible ischemia, and viability scores for lased and nonlased (septum) segments were calculated. The results were compared using a paired Student’s t test, and a p value of less than 0.05 was considered statistically significant.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Operative Data
The operation was performed through a limited thoracotomy in all but 1 patient, who underwent a thoracoscopic approach. In this patient, surgical and visual instruments were introduced through three small ports in the anterolateral thoracic wall. The mean duration of the entire procedure was 120 ± 40 minutes, whereas the TMLR portion lasted a mean of 27 ± 13 minutes (range, 10 to 60 minutes). A mean of 33 ± 6 complete channels (range, 22 to 46 channels) were created in each patient. The mean number of pulses required per channel was 9 ± 2 (mean energy delivered per channel, 14 ± 3 J), with a mean of 296 ± 84 pulses per patient. The patients were extubated after a mean of 10 ± 6 hours (range, 1 to 22 hours) and had a mean intensive care unit stay of 22 ± 6 hours (range, 3 to 32 hours).

There were no operative deaths and no major postoperative complications. No patient required chest reexploration for bleeding; the mean blood loss was 347 ± 216 mL. Mild inotropic support (3 to 5 µg · kg^-1 · m^-1) of dobutamine was required in 7 patients. Two patients experienced runs of supraventricular arrhythmias and 3 had transient ST segment depression with negative T waves. The mean peak creatine kinase MB band was 40 ± 27 IU/L (range, 5 to 107 IU/L); enzyme elevation was not correlated with the number of channels created, electrocardiographic changes, or the need for inotropic support. Patients were discharged 4 to 15 days after TMLR, for a mean hospital stay of 8 ± 4 days.

Follow-up Data
There were two late deaths. One patient died 40 days after TMLR because of a stroke and another died 4 months after TMLR because of a suspected myocardial infarction. Permission for necropsy was not obtained in either patient. Current survivors have been followed up for a mean of 10 ± 4 months (range, 3 to 15 months), with 15 patients followed up for 3 months, 14 for 6 months, and 7 for 1 year. Cumulative follow-up totals 157 patient-months. At last follow-up, the mean anginal class was 1.8 ± 0.7 (p = 0.001), with 5 (36%) patients in class 1, 7 (50%) in class 2, and 2 (14%) in class 3. Changes in postoperative anginal class are shown in Fig 2. No significant change in medical therapy occurred after operation. Only 2 patients required an increased dosage of medications to control their angina. The mean left ventricular ejection fraction increased from 0.49 ± 0.06 to 0.52 ± 0.03 (p = not significant) and the mean time on the cycle ergometer increased from 3.4 ± 1.5 to 5.1 ± 1.9 minutes (p = 0.05). The mean number of hospitalizations because of angina decreased from 5.0 ± 2.0 in the 6 months before TMLR to 1.5 ± 1.0 in the 6 months after TMLR (p = 0.001) (Table 2).

View larger version (25K): [in this window] [in a new window]   Change in the percentage of segments with fixed and reversible ischemia 3 and 6 months after operation. There is no statistically significant difference compared with preoperative values. (ns = not significant.)

View larger version (22K): [in this window] [in a new window]   Change in the viability score 3 and 6 months after operation of the lased and nonlased segments. There is no statistically significant difference compared with preoperative values. (ns = not significant.)

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

Despite such gratifying results, the mechanism by which TMLR improves myocardial perfusion is still unclear. Transmyocardial channels should help blood flow from the left ventricular cavity to the myocardium to reproduce the blood supply of the amphibian heart. However, little evidence has been provided that such channels remain patent for a long period. Cooley and co-workers [11], examining the heart of a patient who died 3 months after undergoing TMLR using a high-energy CO₂ laser, provided histologic evidence of patent laser channels. However, other investigators have been unable to demonstrate channel patency even soon after TMLR using a CO₂ laser [12]. More recently, a report from the German Heart Institute in Berlin [13] showed that, in 8 patients who died after TMLR, almost all the channels created with a CO₂ laser had closed within 20 days of operation and there were no connections between the channels and the ventricular cavity. These findings suggest that the clinical benefit of TMLR might result simply from an inflammatory response to injury, whereas the occurrence of a true neoangiogenesis has yet to be proved [12][13].

As an alternative to the CO₂ laser, the holmium:yttrium-aluminum garnet laser has been used experimentally, with conflicting opinions concerning its efficacy. Kohmoto and colleagues [14] have shown that blood flow does not seem to occur through channels drilled with the holmium laser. Likewise, others [15] have reported that direct laser revascularization does not provide immediate benefit in dogs with acute myocardial ischemia. On the other hand, Yano and colleagues [16] demonstrated that channels created on the endocardial surface with a holmium laser preserved myocardial function during acute ischemia in dogs.

We began a clinical trial of TMLR using a holmium laser in 1995. From the surgical point of view, TMLR with this equipment has proved to be an extremely simple and well-tolerated procedure. The fact that the holmium laser beam can be transmitted through a flexible optical fiber, which is easy to handle and manipulate, is a distinct advantage of this system. This enabled us to perform one of the procedures through thoracoscopy, suggesting that in the era of minimally invasive operations, TMLR should be amenable to such an approach. We have treated 16 patients, all of whom were not considered to be candidates for PTCA or CABG because of unfavorable coronary anatomy, with low morbidity and no operative deaths. These results compare favorably with those of Cooley and co-workers [5] and Horvath and associates [6], who observed 10% and 20% hospital mortality rates, respectively, for TMLR using a CO₂ laser. In accordance with such studies, we also observed satisfactory results in terms of symptomatic improvement, reduction in the number of hospitalizations, and increased tolerance to exercise at a maximum follow-up of 15 months. However, we were unable to demonstrate variations in perfusion by thallium scans at 3 and 6 months after TMLR. These results differ from those reported by Horvath and associates [6], who observed in technetium-99m sestamibi ventricular scans a significant improvement in areas of reversible ischemia that had been treated with a CO₂ laser. The perfusion of lased and nonlased segments did not change on ²⁰¹Tl-SPECT in the series of Frazier and colleagues [4]; however, in some patients, these investigators could demonstrate an increase in subendocardial perfusion using positron emission tomography. Whether our inability to duplicate such results is related to the imaging technique used or the different laser technology used remains unclear.

One of the limitations of the present study is the small number of patients enrolled. This is due mainly to the fact that rigid selection criteria were followed, which led us to exclude many patients who initially were evaluated for this procedure. To include more patients in the study, TMLR should have been combined with CABG. However, we prefer to perform TMLR as the sole alternative surgical option for patients with otherwise untreatable coronary artery disease so as to collect data that could allow more extended application of this procedure in the near future.

In conclusion, TMLR using a holmium laser is a safe and well-tolerated procedure that results in clinical improvement in most patients who have coronary artery disease that is not amenable to traditional surgical treatment. Changes in myocardial perfusion are not evident within the first 6 postoperative months and thus a longer observation period and a larger number of patients probably are needed. Randomized studies comparing patients who are treated medically with those who undergo TMLR also should be helpful in establishing the benefits and limits of this procedure [17].

	Acknowledgments

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
We thank Sorin Biomedica, Saluggia, Italy, official distributor of the Eclipse TMLR holmium laser, for providing technologic support and, in particular, Enrico Pasquino and Gioacchino De Giorgi for their continuous help during the study and data collection. This investigation also was made possible by the skillful technical assistance of Rocco Colangelo and Stefano Niccolai.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
This article has been selected for the open discussion forum on the STS Web site: http://www.sts.org/annals

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

1. Mirhoseini M, Cayton MM, Shelgikar S, Fisher JC Laser myocardial revascularization. Lasers Surg Med 1986;6:459-461.[Medline]
2. Smith JA, Dunning JJ, Parry AJ, Large SR, Wallwork J Transmyocardial laser revascularization. J Card Surg 1995;10:569-572.[Medline]
3. Mirhoseini M, Shelgikar S, Cayton MM New concepts in revascularization of the myocardium. Ann Thorac Surg 1988;45:415-420.[Abstract]
4. Frazier OH, Cooley DA, Kadipasaoglu KA, et al. Myocardial revascularization with laser. Preliminary findings. Circulation 1995;92(Suppl 2):58-65.[Abstract/Free Full Text]
5. Cooley DA, Frazier OH, Kadipasaoglu KA, et al. Transmyocardial laser revascularization: clinical experience with twelve-month follow-up. J Thorac Cardiovasc Surg 1996;111:791-797.[Abstract/Free Full Text]
6. Horvath KA, Mannting F, Cummings N, Shernan SK, Cohn LH Transmyocardial laser revascularization: operative techniques and clinical results at two years. J Thorac Cardiovasc Surg 1996;111:1047-1053.[Abstract/Free Full Text]
7. Schaldach M Cardiovascular laser applications. Artif Organs 1990;14:28-40.[Medline]
8. Mirhoseini M, Cayton MM Revascularization of the heart by laser. J Microsurg 1981;2:253-260.[Medline]
9. Mirhoseini M, Fisher JC, Cayton M Myocardial revascularization by laser: a clinical report. Lasers Surg Med 1983;3:241-245.[Medline]
10. Horvath KA, Smith WJ, Laurence RG, Schoen FJ, Appleyard RF, Cohn LH Recovery and viability of an acute myocardial infarct after transmyocardial laser revascularization. J Am Coll Cardiol 1995;25:258-263.[Abstract]
11. Cooley DA, Frazier OH, Kadipasaoglu KA, Pehlivanoglu S, Shannon RL, Angelini P Transmyocardial laser revascularization. Anatomic evidence of long-term channel patency. Tex Heart Inst J 1994;21:220-224.[Medline]
12. Fleischer KJ, Goldschmidt-Clermont PJ, Fonger JD, Hutchins GM, Hruban RH, Baumgartner WA One-month histologic response of transmyocardial laser channels with molecular intervention. Ann Thorac Surg 1996;62:1051-1058.[Abstract/Free Full Text]
13. Krabatsch T, Schaper F, Leder C, Tulsner J, Thalmann U, Hetzer R Histological findings after transmyocardial laser revascularization. J Card Surg 1996;11:326-331.[Medline]
14. Kohmoto T, Fisher PE, Gu A, et al. Does blood flow through holmium:YAG transmyocardial laser channels?. Ann Thorac Surg 1996;61:861-868.[Abstract/Free Full Text]
15. Whittaker P, Kloner RA, Przyklenk K Laser-mediated transmural myocardial channels do not salvage acutely ischemic myocardium. J Am Coll Cardiol 1993;22:302-309.[Abstract]
16. Yano OJ, Bielefeld MR, Jeevanandam V, et al. Prevention of acute regional ischemia with endocardial laser channels. Ann Thorac Surg 1993;56:46-53.[Abstract]
17. Wallwork J, Schofield P, Caine N, Sharples L, Buxton M Health technology assessment: TMR trials and tribulations. Lancet 1996;348:1386.

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