JTCS Speed Up Your Browser
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
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 A. Horvath
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Horvath, K. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Horvath, K. A.
Related Collections
Right arrow Cardiac - other
Right arrowRelated Article

J Thorac Cardiovasc Surg 2001;122:647-648
© 2001 The American Association for Thoracic Surgery

Editorials

Shedding light on denervation and transmyocardial laser revascularization

Keith A. Horvath, MD

From the Department of Cardiac and Thoracic Surgery, Northwestern Medical Faculty Foundation, Chicago, Ill.

Received for publication June 5, 2001. Accepted for publication June 8, 2001. Address for reprints: Keith A. Horvath, MD, Department of Cardiac and Thoracic Surgery, Northwestern Medical Faculty Foundation, 201 E Huron Ave, 10-125, Chicago, IL 60611-3008.

See related article on page 712.

With more than 6000 patients treated and with 70% to 75% of these patients having a significant improvement in their angina symptoms, one would think that the mechanism whereby transmyocardial laser revascularization (TMLR) achieves its effect would be well understood. Of the many possible mechanisms, including angiogenesis, channel patency, alterations of ventricular compliance, placebo effect, and denervation, it is the latter that is the most difficult to prove or disprove. Clinical studies have indirectly demonstrated that denervation does not play the primary role, a virtue of improvement in perfusion, as demonstrated by nuclear spec scans and positron emission tomograpic scans.Go Go 1-5 Additionally, functional improvement with dobutamine stress echocardiographyGo 6 and cine magnetic resonance imagingGo 7 also indicates that denervation is not the contributing mechanism. Furthermore, there is no significant increase in the number of acute myocardial infarctions postoperatively, despite a significant increase in exercise tolerance and activity levels.

In this issue, Minisi and associatesGo 8 have reported on an elegant set of experiments designed to evaluate the effect of TMLR on reflexes mediated by left ventricular receptors with sympathetic afferent fibers. Their results indicate that TMLR does not acutely interrupt the afferent nerves, which transmit the perception of anginal pain. These results are somewhat different from others that have been reported, and this is due to Minisi and colleagues&' efforts to isolate the reflex responses by using an animal preparation with sinoaortic denervation and vagotomy. As a result, they were also able to demonstrate that the reflex circuitry was completely intact after TMLR. However, as the authors note, a major limitation of this study is that these results are from normal canine myocardium and may not be applicable to ischemic myocardium in human subjects. It does demonstrate that the amount of damage inflicted by TMLR is not enough to denervate normal myocardium.

The question of the extent of laser-induced injury and the ensuing response is an important one. Recently, attempts to perform laser revascularization percutaneously with a catheter have met with mixed results.Go Go 9-11 In fact, a placebo-controlled trial has demonstrated no benefit of percutaneous myocardial laser revascularization.Go 11 The revascularization that can be achieved percutaneously is limited because of the delivery of the laser energy to a very thin layer of the subendocardium (2-3 mm) and the difficulty with navigating the catheter within the ventricle to provide an adequate distribution of the laser treatment. One other factor that may play a role is the type of laser light that is used. Minisi and associates have used a holmium:YAG laser. This laser is delivered through a fiber, which is manually advanced through the myocardium. However, it is unknown whether the injury created is principally caused by a mechanical effect of the fiber or caused by laser ablation. In the beating heart it is impossible to ensure that a fiber pushed by hand is advancing behind the wave of laser ablation. It would therefore be of interest to perform further experiments, not only in an ischemic model but also using the fiber alone or using other types of laser light that are not dependent on fiber delivery (for example, carbon dioxide) to confirm their results and provide clinical correlation. This difference in laser light has become clinically apparent over the long term because those treated with a holmium:YAG laser have had a significant increase in angina over 3 years after treatment.Go 11 In contrast, patients treated with carbon dioxide TMLR have continued angina relief over 5 years after treatment.Go 13

Demonstrating that TMLR does not denervate the heart is an important piece of the mechanistic puzzle.

References

  1. Frazier OH, Cooley DA, Kadipasaoglu KA, Pehlivanoglu S, Lindenmeir M, Barasch E, et al. Myocardial revascularization with laser: preliminary findings. Circulation. 1995;92(Suppl):II-58-65.
  2. 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;111:1047-53.[Abstract/Free Full Text]
  3. Horvath KA, Cohn LH, Cooley DA, Crew JR, Frazier OH, Griffith BP, et al. 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;113:645-54.[Abstract/Free Full Text]
  4. Schofield PM, Sharples LD, Caine N, Burns S, Tait S, Wistow T, et al. Transmyocardial laser revascularization in patients with refractory angina: a randomized controlled trial. Lancet. 1999;353:519-24.[Medline]
  5. Frazier OH, March RJ, Horvath KA. Transmyocardial revascularization with a carbon dioxide laser in patients with end-stage coronary artery disease. N Engl J Med. 1999;341:1021-8.[Abstract/Free Full Text]
  6. Donovan CL, Landolfo KP, Lowe JE, Clements F, Coleman RB, Ryan T. Improvement in inducible ischemia during dobutamine stress echocardiography after transmyocardial laser revascularization in patients with refractory angina pectoris. J Am Coll Cardiol. 1997;30:607-12.[Abstract]
  7. Horvath KA, Kim RJ, Judd RM, Parker MA, Fullerton DA. Contrast enhanced MRI assessment of microinfarction after transmyocardial laser revascularization. Circulation. 2000;102(Suppl):II-765.
  8. Minisi AJ, Topaz O, Quinn MS, Mohanty LB. Cardiac nociceptive reflexes after transmyocardial laser revascularization: implications for the neural hypothesis of angina relief. J Thorac Cardiovasc Surg. 2001;122:712-9.[Abstract/Free Full Text]
  9. Oesterle SN, Sanborn TA, Ali N, Resar J, Ramee SR, Heuser R, et al. Percutaneous transmyocardial laser revascularization for severe angina: the PACIFIC randomized trial. Lancet. 2000;356:1705-10.[Medline]
  10. Stone GW, Rubinstein P, Schmidt D, Kosinski EJ, Mishkel G, Teirstein PS. A prospective, randomized, multicenter trial of percutaneous transmyocardial laser revascularization in patients with non-recanalizable chronic total occlusions. Circulation. 2000;102(Suppl):II-689.
  11. Leon MB, Baim DS, Moses JW, Laham RJ, Knopf W, Reisman M, et al. A randomized blinded clinical trial comparing percutaneous laser myocardial revascularization (using Biosense LV mapping) vs placebo in patients with refractory coronary ischemia. Circulation. 2000;102(Suppl):II-565.
  12. De Carlo M, Milano AD, Pratali S, Levantino M, Mariotti R, Bortolotti U. Symptomatic improvement after transmyocardial laser revascularization: How long does it last? Ann Thorac Surg. 2000;70:1130-3.[Abstract/Free Full Text]
  13. Horvath KA, Aranki SA, Cohn LH, Frazier OH, Kadipasaoglu KA, Boyce SW, et al. Sustained angina relief five years after transmyocardial revascularization with a CO2 laser. Circulation. 2000;102(Suppl):II-764.

Related Article

Cardiac nociceptive reflexes after transmyocardial laser revascularization: Implications for the neural hypothesis of angina relief
Anthony J. Minisi, On Topaz, M. Susan Quinn, and Laxmi B. Mohanty
J. Thorac. Cardiovasc. Surg. 2001 122: 712-719. [Abstract] [Full Text] [PDF]




This Article
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 A. Horvath
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Horvath, K. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Horvath, K. A.
Related Collections
Right arrow Cardiac - other
Right arrowRelated Article

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