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J Thorac Cardiovasc Surg 1999;118:977
© 1999 Mosby, Inc.
LETTERS TO THE EDITOR |
4101 S Wappel Dr
Columbia, MO 65203
To the Editor:
Zenati, Cohen, and Griffith
1 express support for the development of centers in which differentrevascularization procedures would be performed in the same patient by teamscomposed of interventional cardiologists and cardiovascular surgeons. Willmyocardial laser revascularization (MLR), either percutaneous or surgical,find its place in such teamwork when its original idea of perfusion of theleft ventricle from its cavity is no longer valid? 2
In the meantime, a new concept trying to explain why MLR has been beneficialto some patients has emerged: angiogenesis as a nonspecific response of themyocardium to injury. All the same, this concept is usually considered unfitto serve as a vehicle for MLR because this procedure leads only rarely tothe improvement of objective parameters such as cardiac perfusion and function,exercise capacity, and survival. 2
Before MLR is abandoned, we must be sure that it (1) has been used correctlyand (2) was applied to suitable patients. I am afraid this has not alwaysbeen the case.
Angiogenesis fulfills its purpose only if a source of oxygenated bloodis available. This condition provided, angiogenesis diminishes ischemia solelyif it leads to the development of collateral vessels linking the ischemicwith the well-perfused myocardium. 3 In agreement with these concepts, cardiomyocyte death induced by MLRwould lead to inflammatory angiogenesis and wound healing reaction. Newlyformed capillaries would connect blood vessels of the lased ischemic regionwith blood vessels of neighboring well-perfused areas. The angiogenesis wouldnot subside after the healing of laser channels because friction between noncompliantlaser channel scars and the contractile surrounding myocardium would inducecontinuous injury and inflammation. 4 New capillaries would not regress because of a pressure gradient betweenthe well-perfused myocardium and the ischemic region. 3 The remodeling of capillary-sized collaterals intoarterioles and arteries would complete the revascularization, that is, thecollateralization of the ischemic region.
Contrary to the above hypotheses, MLR has been used mostly in patientswith diffuse multivessel end-stage coronary artery disease with contraindicationsto percutaneous transluminal coronary angioplasty and coronary artery bypassgrafting. It is obvious that angiogenesis is of no use if the whole ventricleis ischemic. On the contrary, the use of MLR in combination with coronaryartery bypass grafting and/or coronary angioplasty (as it would be practicedin integrated revascularization centers) is an excellent idea. The conventionaltechniques would provide the source of well-oxygenated blood wherever possible,and MLR would facilitate the development of collateral vessels in the areasinaccessible for traditional revascularization. It is worthy of note thatMirhoseini, Shelgikar, and Cayton, 5 the inventors of MLR, used this method in combination with coronaryartery bypass grafting when they started to apply it to patients. This undoubtedlyexplains their success. Recently, Trehan and colleagues 6 used MLR in combination with minimally invasive coronaryartery bypass grafting and claimed excellent results. All this suggests thatMLR, if used in conjunction with other methods of revascularization, willfind its place in the therapeutic armamentarium used against ischemic heartdisease.
12/8/101411
References
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