Dissociation Between Improvement in Angina Pectoris and Myocardial Perfusion After Transmyocardial Revascularization With an Excimer Laser Gerald J. Kavanagh, MD, Peter Whittaker, PhD, Curtis A. Prejean Jr., MD, Beverly R. Firth, MN, Robert A. Kloner, MD, PhD, and Gregory L. Kay, MD T he original goal of creating myocardial channels was to revascularize ischemic tissue, and hence the term transmyocardial revascularization (TMR) was used. Although clinical trials have consistently re- ported a reduction in angina, 1,2 the evidence for re- vascularization has been conflicting. 1–3 The first re- vascularization hypothesis was that channels would create a reptilian-like circulation in mammalian hearts, allowing immediate blood flow from the ven- tricular cavity through channels and into the tissue via sinusoidal spaces. 4 The hypothesis was discredited because (1) many studies found no acute perfusion, 5 (2) the existence of sinusoids in normal human hearts has never been documented, 6 and (3) channels made with carbon dioxide and holmium:yttrium-aluminium- garnet (YAG) lasers, the devices most often used, become occluded by fibrosis. 7,8 TMR with these in- frared lasers provokes a vasculogenic/angiogenic re- sponse and thus generates a second revascularization hypothesis. However, whether such vascular growth increases perfusion is unknown. In contrast to the closed channels found after infrared laser TMR, some animal studies have reported open channels with vas- cular connections to surrounding myocardium several months after TMR with ultraviolet lasers. 9,10 We spec- ulated that after ultraviolet laser TMR, increased blood flow might be detected in patients. Two trials using ultraviolet excimer lasers reported a 2-class reduction in patients’ Canadian Cardiovascular Soci- ety (CCS) functional class; however, neither study assessed perfusion. 11,12 On the other hand, a case report, in which excimer laser TMR was performed together with bypass graft surgery, claimed improved perfusion. 13 Thus, we examined the effect of excimer laser TMR with an emphasis on perfusion assessment. ••• Ultraviolet laser TMR was performed in 7 patients (4 men and 3 women, aged 62  4 years). Patients selected for the study had regions of reversibly isch- emic myocardium identified by single-photon emis- sion computed tomography (SPECT). In addition, catheterization revealed arteries that were considered unsuitable candidates for either bypass surgery or angioplasty and that supplied viable tissue. The pa- tients’ CCS functional class and treadmill exercise time were determined before TMR and at follow-up. A xenon chloride excimer laser ( = 308 nm; AccuLase, Inc., Carlsbad, California) was used to make channels at a pulse energy of 9 mJ, a pulse width of 40 ns, and a pulse rate of 240 Hz. The energy was coupled into a 600-m diameter optic-fiber system, which was advanced at a velocity of 1.55 cm s -1 . Patients were prepared for anesthesia and surgery in a standard manner. Hearts were exposed by a left tho- racotomy, usually through the fifth intercostal space. Any adhesions were dissected and the heart exposed. The number of channels made was determined by the size of the apparent perfusion defect on stress. Trans- esophageal echocardiography was used to assess myo- cardial wall thickness and hence set the advancement distance of the fiber delivery system. In addition, transesophageal echocardiography was used to assess transmural penetration of the optic fiber, as indicated by the presence of bubbles in the ventricular cavity. SPECT data were acquired as previously de- scribed. 14 Briefly, a single-detector camera (Orbiter, Siemens, Hoffman Estates, Illinois) fitted with a low- energy high-resolution collimator was used in a step- and-shoot rotation mode with 32 projections over a 180° range. For each projection, data were collected over 40 seconds for gated SPECT. The patients’ car- diac images were collected from a rest thallium-201 (2.8 to 3.1 mCi) and stress technetium-99m sestamibi (20.0 to 26.5 mCi) dual isotope procedure. We present data only from the stress images, obtained at peak pharmacologic stress induced by dipyridamole or do- butamine. A standard, automated image-analysis pro- gram (QGS, Cedars-Sinai Hospital, Los Angeles, Cal- ifornia) was used to divide the left ventricle into 5 regions (septum, anterior, inferior, lateral, and apex) and to determine the relative perfusion within each region. Perfusion was expressed as the relative mean voxel intensity in each region normalized as a percent- age of the brightest voxel in the image. For each patient, the average perfusion score for treated and untreated regions was calculated for scans obtained before TMR and at the last follow-up. In addition, ejection fraction was calculated from SPECT mea- surement of end-systolic and end-diastolic left ven- tricular volume. All data are expressed as mean  SE. The analysis of the SPECT perfusion data was done using 2-factor analysis of variance, with replication followed by ap- plication of the Newman-Keuls test for intergroup comparison. Analysis of the exercise times was done by repeated-measures analysis of variance, whereas From the Department of Nuclear Medicine, The Heart Institute, Good Samaritan Hospital, and Department of Medicine, Cardiology Sec- tion, University of Southern California, Los Angeles, California. This study was supported in part by Baxter Healthcare Corporation, Irvine, California. Dr. Whittaker’s address is: The Heart Institute, Good Sa- maritan Hospital, 1225 Wilshire Boulevard, Los Angeles, California 90017. E-mail: pwhittaker@dnamail.com. Manuscript received May 22, 2000; revised manuscript received and accepted July 24, 2000. 229 ©2001 by Excerpta Medica, Inc. All rights reserved. 0002-9149/01/$–see front matter The American Journal of Cardiology Vol. 87 January 15, 2001 PII S0002-9149(00)01326-6