EJCTS Click here for details of sales representative
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Keith B Allen
Robert D Dowling
David A Heimansohn
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Allen, K. B
Right arrow Articles by Shaar, C. J
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Allen, K. B
Right arrow Articles by Shaar, C. J

Eur J Cardiothorac Surg 1998;14:S100-S104
© 1998 Elsevier Science NL

Transmyocardial revascularization utilizing a holmium:YAG Laser 1

Keith B Allena,*, Robert D Dowlingb, David A Heimansohna, Eileen Reitsmaa, Luanne Didelotb, Carl J Shaara

a Department of Cardiovascular/Thoracic Surgery, St. Vincent Hospital and Health Care Center Indianapolis, IN, USA
b Department of Cardiovascular/Thoracic Surgery, University of Louisville, Louisville, KY, USA

* Corresponding author. 8333 Naab Road, Suite 300, Indianapolis, IN 46260. Tel.: +1 317 3383551; fax: +1 317 3389209.


   Abstract
Top
 Abstract
1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 References
 
Objective: To evaluate the efficacy of transmyocardial revascularization performed on patients with refractory class IV or unstable angina with a holmium:yttrium-aluminum-garnet laser. Methods: Transmyocardial revascularization with a holmium:yttrium-aluminum-garnet laser was performed in 42 patients with refractory angina who were not candidates for percutaneous transluminal coronary angioplasty or coronary artery bypass grafting. Patients had either Canadian Heart Association class IV angina (n=23) or unstable angina (n=19) and were unable to be weaned from intravenous nitroglycerin. Preoperative thallium studies identified the extent and location of reversible ischemia. Operative exposure was via a limited left anterior thoracotomy. An average of 45±11 laser channels were created with a mean operative time of 106±38 min. Results: Perioperative mortality was 12% (5/42) with no late deaths. Complications included ventricular 7.1%(3/42) and atrial 4.7% (2/42) arrhythmias, reoperation for chest-wall hemorrhage 2% (1/42), and respiratory failure requiring reintubation 2% (1/42). Intra-aortic balloon pump placement was required in 12% (5/42). The mean postoperative length of stay was 5.5±4.9 (1–25) days. Mean follow-up on 100% of patients is 5.4±3.0 (1–12) months. At 3 (n=33) and 6 (n=21) months follow-up the mean angina class was 1.5±0.1 (P<0.002) and 1.1±0.1 (P<0.001), respectively. Conclusions: Transmyocardial revascularization utilizing a holmium:yttrium-aluminum-garnet laser resulted in a significant reduction in angina class and was beneficial in patients with refractory angina untreatable by conventional methods.

Key Words: Transmyocardial revascularization • Holmium:YAG Laser • Laser surgery


   1. Introduction
Top
 Abstract
 1. Introduction
2. Materials and methods
 3. Results
 4. Discussion
 References
 
Medically refractory angina which is not amenable to percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG) continues to frustrate clinicians. Indirect methods of myocardial revascularization such as Beck's omentopexy, [1]Vineberg's thoracic artery implantation, [2]and Sen's mechanical myocardial acupuncture [3, 4]had limited success and are of historical interest only. Mirohseini and associates [5–9]proposed transmyocardial revascularization (TMR) as a means of providing oxygenated left ventricular blood to ischemic myocardium through laser generated transmural channels. While there is a growing body of literature supporting the use of TMR performed with a carbon dioxide (CO2) laser, this report provides preliminary clinical results regarding the efficacy of TMR performed with a holmium:yttrium-aluminum-garnet (Ho:YAG) laser in patients with refractory angina that were untreatable by conventional methods.


   2. Materials and methods
Top
 Abstract
 1. Introduction
 2. Materials and methods
3. Results
 4. Discussion
 References
 
2.1 Patient selection and demographics
Between June, 1996, and January, 1997, 42 patients with refractory angina not amenable to PTCA or CABG were treated with TMR utilizing a Ho:YAG laser at St. Vincent Hospital and Health Care Center, Indianapolis, IN, and The University of Louisville Hospital, Louisville, KY. Study protocols were approved by the Institutional Review Board at each institution as well as the United States Food and Drug Administration. Inclusion criteria included: (i) patients with stable class IV angina (n=23) or patients with unstable angina (n=19) who were unable to be weaned from intravenous antianginals (Canadian Cardiovascular Society definition), (ii) coronary artery disease not amenable to PTCA or CABG, (iii) evidence of ischemic myocardium (defined as >10% reperfusion) as determined by a myocardial perfusion study and (iv) ejection fraction greater than 25%. Exclusion criteria included: intolerance to anesthesia, uncompensated heart failure, severe arrhythmias, chronic anticoagulation for mechanical heart valves or chronic atrial fibrillation (due to increased risk of postoperative bleeding) and hemorrhagic propensity. Patient demographics are outlined in Table 1 . Preoperatively, 93% (39/42) of patients were in Canadian Angina class IV and 7% (3/42) were in class III.


View this table:
[in this window]
[in a new window]
  		Table 1. Patient demographics
 
2.2 Operative technique
Anesthesia includes short-acting inhalation agents supplemented with low-dose narcotics and propofol. A single lumen endotracheal tube is routinely used, ventilation with a decreased tidal volume and an increased respiratory rate provides excellent visualization of the heart even in patients with emphysema. External defibrillator pads are utilized on all patients. Patients are positioned in a 45° right lateral decubitus position and undergo a limited left anterolateral thoracotomy in the fifth intercostal space. A lower incision is always desirable since exposure of the inferior surface of the heart is difficult through a higher interspace. The pericardium is identified and opened longitudinally and anterior to the phrenic nerve. Adhesions, when present, are divided to expose the distal two-thirds of the left ventricle. Previous bypass grafts, if still patent, are left undisturbed to avoid distal embolization. A lidocaine bolus (100 mg) is administered along with 2 g of magnesium sulfate prior to beginning the laser portion of the case.

2.3 Laser
A 20-W pulsed Ho:YAG laser (Eclipse Surgical Technologies, Sunnyvale, CA) is used to create the transmyocardial channels. Laser calibrations are set to deliver 6–8 W of power per laser pulse at a rate of five pulses/s from a flexible 1-mm optical fiber. Application of the energy is controlled with a foot switch and is not gated to the cardiac cycle; 3–8 pulses are typically required to traverse the myocardium. Channels are placed every square centimeter throughout the distal two-thirds of the left ventricle avoiding areas which are obviously scared. Three to five channels are placed followed by 2–3 min of digital pressure to obtain hemostasis and allow the myocardium to recover. This process is repeated until 30–50 laser channels have been placed. A mean of 45±11 channels were created with a mean operative time of 106±38 min. Intraoperative arrhythmias are unusual if channels are placed slowly; epicardial ligation of a laser channel for persistent bleeding has not been required.

The laser energy, which is absorbed by the blood in the ventricle, produces an acoustic image analogous to steam that is readily visible by transesophageal echocardiography (TEE). Initially, TEE was utilized to confirm penetration of the laser into the left ventricle. After several cases, however, tactile and auditory training enable the surgeon to confirm transmyocardial penetration without TEE.

The chest incision is closed per routine with a single posterior chest tube. Patients are routinely extubated in the operating room and transferred to the standard open heart recovery unit. Postoperative pain management is accomplished for the first 24 h with a patient-controlled analgesia pump and ketorolac (Toradol, Roche, Nutley, NJ) and then by oral narcotics. Patients are maintained in the cardiac recovery unit overnight with transfer to a telemetry unit the morning after surgery. Patients with unstable angina, however, often require several additional days in the intensive care unit as they are weaned from their intravenous antianginals. Unstable patients who were on heparin preoperatively are started on low-dose intravenous heparin (1000 units/h) beginning 6 h after surgery if there is no evidence of bleeding and receive their first dose of coumadin on the night of surgery. Cardiac suppressants (ß-blockers, calcium-channel blockers) are avoided during the first 48 h but nitrates and angiotensin-converting enzyme inhibitors are resumed the evening of surgery.

2.4 Patient follow-up
Mean follow-up in 100% of patients is 5.4±3.0 (range 1–12) months. Postoperatively, all patients are maintained on their same preoperative medication regimen for a duration of 3 months at which time antianginal medications are weaned as tolerated. Following TMR, angina classification is determined at 3, 6 and 12 months with repeat myocardial perfusion studies at 3 and 12 months.

2.5 Statistical methods
All statistical analyses and descriptive statistics were determined using JMP® Statistical Discovery Software (SAS Institute, Cary, NC). Angina class at baseline and follow-up were compared with the use of a two-sided paired t-test. Differences were considered significant at P<0.05. Results are expressed as mean±standard deviation. Survival data were analyzed using the Kaplan–Meier methods.


   3. Results
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
4. Discussion
 References
 
Perioperative mortality was 12% (5/42) with no late deaths. The cause of death for each patient is listed in Table 2 . Three of the postoperative deaths occurred in patients with unstable angina and two deaths occurred in patients with stable class IV angina. Perioperative complications are listed in Table 3 . The mean postoperative length of stay was 5.5±4.9 (range 1–25) days. Following TMR, angina class decreased significantly at 3 and 6 months compared to the preoperative baseline and this is depicted in Fig. 1 A–C. Mean angina classification at 3 (n=33) and 6 (n=21) months was 1.5±0.1 (P<0.001) and 1.1±0.1 (P<0.002), respectively. In addition, at 3 and 6 months follow-up, 87.8% (29/33) and 85.7% (18/21) of patients had a decrease of two or more angina classes, respectively (Fig. 2 ). The Kaplan–Meier survival estimate at 1 year is 88%. Detailed comparisons between pre- and post-operative myocardial perfusion studies which are blindly interpreted at a central core laboratory are not available in adequate numbers for meaningful statistical analysis.


View this table:
[in this window]
[in a new window]
  		Table 2. Mortality in TMR patients
 

View this table:
[in this window]
[in a new window]
  		Table 3. Perioperative complications
 

Figure 1
View larger version (14K):
[in this window]
[in a new window]
  		Fig. 1. (a) Preoperative angina class. (b) Angina class at 3-month follow-up. (c) Angina class at 6-month follow-up.

 

Figure 2
View larger version (12K):
[in this window]
[in a new window]
  		Fig. 2. Percentage of patients who dropped ≥2 angina classes at 3 and 6 months postoperatively.

 

   4. Discussion
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
References
 
Successful myocardial revascularization relies on improved delivery of oxygenated blood to ischemic myocardium. While the mainstays of conventional revascularization are CABG and PTCA, transmyocardial revascularization may prove beneficial in patients with refractory angina who for anatomic and physiologic reasons are not candidates for conventional therapies.

Mirohseini and associates [5]first advanced laser TMR based on Sen's earlier concept of mechanical myocardial acupuncture. They proposed the use of a CO2 laser to create transmural channels to perfuse ischemic myocardium. It was theorized that oxygenated left ventricular blood accessed the capillary system through the laser channels via sinusoids; a physiologic system analogous to that of the reptilian heart. This theory was compelling considering Wearn's [10]l933 description of a rich myocardial sinusoidal network present in the human heart.

Recent clinical studies utilizing a high powered CO2 laser have demonstrated that TMR reduces angina along with angina associated hospital admissions, and improves myocardial perfusion [11–14]. Furthermore, a prospective randomized trial in patients with refractory angina showed that TMR, when compared to continued medical management, significantly improved event-free survival [15]. A similar prospective multicenter randomized trial utilizing the Ho:YAG laser is underway; to date enrollment has been 180 patients at 16 centers.

The mechanism by which TMR reduces the discomfort of severe or unstable angina is unknown. Several conflicting reports are available which propose various theories to explain the mechanism of angina relief [16–18]. There is growing evidence, however, that channel patency and angiogenesis are important components in the clinical success seen with CO2 TMR [14, 17, 19–21].

Myocardial perfusion studies ideally could be used to document improved myocardial blood flow following TMR. Animal studies have utilized non-ischemic or acute occlusion models which are not representative of chronic myocardial ischemia seen clinically, and have produced conflicting results [16, 22]. Myocardial perfusion studies obtained in clinical trails following CO2 TMR have been contradictory with some studies demonstrating improvement [13, 15]while others show no significant change. Positron emission tomography (PET) scanning has demonstrated improved perfusion following CO2 TMR in a limited number of patients. Our institution is currently evaluating the effects of Ho:YAG TMR on perfusion, metabolism, and sympathetic innervation of ischemic myocardium using pre and postoperative PET scan evaluation.

Operative mortality observed in this study is similar to that previously reported for patients with stable class IV angina [12, 13]and much less than that previously reported for unstable angina patients receiving TMR by CO2 laser [15]. No statistical correlation was observed between age, preoperative ejection fraction or acuity of procedure and operative mortality.

It has been suggested that the subjective angina class improvement provided by TMR may represent a placebo effect. Angina class data from 36 patients in the phase I Ho:YAG TMR study (unpublished) and studies utilizing CO2 TMR, however, have demonstrated a persistent reduction in angina for up to 2 years after the procedure [12, 23].

Two prospective multicenter randomized TMR trails utilizing a Ho:YAG laser are currently underway. One compares TMR as the sole therapy with maximal medical management in patients with refractory angina while the other compares TMR combined with CABG versus CABG alone in patients who cannot be completely revascularized. Future applications may also include the treatment of diffuse coronary artery disease in cardiac transplant patients. While these early clinical results with Ho:YAG TMR are encouraging, longer follow-up and perfusion study analyses are needed. Transmyocardial revascularization utilizing the Ho:YAG laser results in a significant reduction in angina classification and is beneficial in patients with refractory angina untreatable by conventional revascularization techniques.


   Footnotes
 
1 Presented at the World Congress on Minimally Invasive Cardiac Surgery, Paris, May 30–31, 1997. Back


   References
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 References
 

  1. Beck CS. The development of a new blood supply to the heart by operation. Ann Surg 1934;102:801-813.
  2. Vineberg A. Clinical and experimental studies in the treatment of coronary artery insufficiency by internal mammary artery implant. J Int Coll Surg 1954;22:503-518.[Medline]
  3. Sen PK, Udwadia TE, Kinare SG, Parulkar GB. Transmyocardial acupuncture, a new approach to myocardial revascularization. J Thorac Cardiovasc Surg 1965;50:181-189.[Medline]
  4. Sen PK, Daulatram J, Kinare SG, Udwadia TE, Parulkar GB. Further studies in multiple transmyocardial acupuncture as a method of myocardial revascularization. Surgery 1968;64:861-870.[Medline]
  5. Mirohsieni M, Muckerheide M, Cayton MM. Transventricular revascularization by laser. Lasers Surg Med 1982;2:187-198.[Medline]
  6. Mirohseini M, Fisher JC, Cayton MM. Myocardial revascuarization by laser. Lasers Surg Med 1983;3:241-245.[Medline]
  7. Mirohseini M, Cayton MM, Shelgikar S, Fisher JC. Clinical report: laser myocardial revascularization. Lasers Surg Med 1986;6:459-461.[Medline]
  8. Mirohseini M, Sheligikar S, Cayton MM. New concepts in revascularization of the myocardium. Ann Thorac Surg 1988;45:415-420.[Abstract]
  9. Mirohseini M, Sheligikar S, Cayton MM. Transmyocardial laser revascularization: a review. J Clin Laser Med Surg 1993;11:15-19.[Medline]
  10. Wearns JT, Mettier SR, Klump TG, Zschiesche AB. The nature of the vascular communications between the coronary arteries and the chambers of the heart. Am Heart J 1933;9:143-170.
  11. Frazier OH, Cooley DA, Kadipasaoglu KA, Pehlivanoglu S, Lindenmeir M, Barasch E, Conger JL, Wilanskuy S, Moore WH, Myocardial revascularization with laser: preliminary findings. Circulation 1995;suppl II:58–65..
  12. Horvath KA, Mannting F, Cummings N, Sherman SK, Cohn LH. Transmyocardial laser revascularization: operative techniques and clinical results at two years. J Thorac Cardiovasc Surg 1996;111(5):1047-1053.[Abstract/Free Full Text]
  13. Horvath KA, Cohn LH, Cooley DA, Frazier OH, Griffith BP, Kadipassaoglu K, Lansing A, Mannting F, March R, Mirhoseini MR, Smith C. Transmyocardial laser revascularization: results of a multicenter trial with transmyocardial laser revascularization used as sole therapy for end-stage coronary artery disease. J Thorac Cardiovasc Surg 1997;113(4):645-654.[Abstract/Free Full Text]
  14. 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]
  15. March RJ, Boyce S, Cooley DA, Fontana G, Griffith BP, Lansing A. Improved event survival following transmyocardial laser revascularization versus medical management in patients with unreconstructed coronary artery disease. The 77th Annual Meeting of The American Association of Thoracic Surgery, May 4–7, 1997, Washington DC 1997;94..
  16. Hardy RI, Bove KE, James FW, Kaplan S, Goldman LA. A histologic study of laser induced transmyocardial channels. Lasers Med Surg 1987;6:563-573.
  17. Owen, E.R., Canfiled, R., Bryant, K., Hopwood, P.R. Observations on the effects of CO2 laser on rat myocardium. Microsurgery 1984;5:140–143..
  18. Kohmoto T, Fisher PE, Gu A, Zhu SM, Yano OJ, Spotnitz HM, Smith CR, Burkhoff D. Does blood flow through holmium:YAG transmyocardial laser channels?. Ann Thorac Surg 1996;61:861-868.[Abstract/Free Full Text]
  19. Mirohseini M, Shelgikar S, Cayton MM. Clinical and histological evaluation of laser myocardial revascularization. J Clin Laser Med Surg 1990;1:236-238.
  20. Horvath KA, Smith WJ, Laurence RG, Schoen JF, Appleyard RF, Cohn LH. Recovery and viability of an acute myocardial infarct after transmyocardial laser revascularization. J Am Coll Cardiol 1995;25:158-163.
  21. Horvath KA, Smith WJ, Laurence RG, Byrne JG, Schoen FJ, Cohn LH. Improved short- and long-term recovery after an acute myocardial infarct treated by transmyocardial laser revascularization. Surg Form 1993;44:220-222.
  22. Landreneau R, Nawarawong W, Laughlin H, Ripperger J, Brown O, McDaniel W, McKnown D, Curtis J. Direct CO2 laser `revascularization' of the myocardium. Lasers Surg Med 1991;11:35-42.[Medline]
  23. Cooley DA, Frazier OH, Kadipasaoglu KA, Lindenmeir MH, Pehlivanoglu S, Kolff JW. Transmyocardial laser revascularization: clinical experience with twelve-months follow-up. J Thorac Cardiovasc Surg 1996;111:791-799.[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 J CARDIOVASC PHARMACOL THERHome page
J. Tasse and R. Arora
Transmyocardial Revascularization: Peril and Potential
Journal of Cardiovascular Pharmacology and Therapeutics, March 1, 2007; 12(1): 44 - 53.
[Abstract] [PDF]

Home page
 Ann. Thorac. Surg.Home page
K. B. Allen, R. D. Dowling, W. W. Angell, D. M. Gangahar, T. L. Fudge, W. Richenbacher, S. L. Selinger, M. R. Petracek, and D. Murphy
Transmyocardial revascularization: 5-year follow-up of a prospective, randomized multicenter trial
Ann. Thorac. Surg., April 1, 2004; 77(4): 1228 - 1234.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
M. Loubani, D. Chin, J. N. Leverment, and M. Galinanes
Mid-term results of combined transmyocardial laser revascularization and coronary artery bypass
Ann. Thorac. Surg., October 1, 2003; 76(4): 1163 - 1166.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
M. De Carlo, A. D. Milano, S. Pratali, M. Levantino, R. Mariotti, and U. Bortolotti
Symptomatic improvement after transmyocardial laser revascularization: how long does it last?
Ann. Thorac. Surg., September 1, 2000; 70(3): 1130 - 1133.
[Abstract] [Full Text] [PDF]

Home page
 NEJMHome page
K. B. Allen, R. D. Dowling, T. L. Fudge, G. P. Schoettle, S. L. Selinger, D. M. Gangahar, W. W. Angell, M. R. Petracek, C. J. Shaar, and W. W. O'Neill
Comparison of Transmyocardial Revascularization with Medical Therapy in Patients with Refractory Angina
N. Engl. J. Med., September 30, 1999; 341(14): 1029 - 1036.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Keith B Allen
Robert D Dowling
David A Heimansohn
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Allen, K. B
Right arrow Articles by Shaar, C. J
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Allen, K. B
Right arrow Articles by Shaar, C. J

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ANN THORAC SURG ASIAN CARDIOVASC THORAC ANN EUR J CARDIOTHORAC SURG
J THORAC CARDIOVASC SURG ICVTS ALL CTSNet JOURNALS