Patients with refractory angina who are not candidates for angioplasty or bypass surgery have been shown to benefit from an alternate approach to revascularization that involves the use of a carbon dioxide laser to create channels between the ventricular blood supply and the myocardium. This technique, which is typically done following thoracotomy, provides excellent results but is associated with a perioperative mortality of 10 to 19 percent. However, use of the holmium:yttrium-aluminum-garnet (YAG) laser allows channels to be created in the presence of the myocardial blood pool, making a transcatheter approach possible. Shawl and associates evaluated the safety of the transcatheter approach in patients undergoing percutaneous transluminal myocardial revascularization (PTMR) for angina.
Patients who met the diagnostic criteria for class III and IV angina established by the Canadian Cardiovascular Society and who were not amenable to any other form of revascularization were eligible for the study. All patients had a preprocedure echocardiography demonstrating a wall thickness of the left ventricular region of more than 9 mm that was to be treated by laser and an ejection fraction of more than 0.25. Patients with high-risk conditions such as decompensated congestive heart failure, sustained ventricular tachycardia, recent ventricular fibrillation, severe aortic stenosis, left ventricular aneurysm or an abnormal aortic arch were excluded from the study.
PTMR was performed through the femoral artery, with the catheter advanced to the apex of the left ventricle and then deflected to place it against the wall to be lased. The laser delivered three sequential pulses of 3.5 W through the 1-mm diameter optical fiber. Channels were created about 1 cm apart from the distal portion of the affected wall to the base of the same wall. Ventriculography was performed both before and after the procedure. Patients were monitored in a telemetry unit for 24 hours after PTMR and resumed taking all pre-PTMR medications.
Twenty-seven patients took part in the study. Of these, most were men who were, on average, 62 years of age and had had previous heart surgery. The laser created an average of 17 channels in each patient. Immediately following PTMR, regional wall motions were either unchanged or improved on repeat left ventriculography or transesophageal echocardiography. All patients were successfully weaned off intravenous nitroglycerin. No procedure-related deaths, pericardial effusions or tamponade, or deaths in the 30-day postprocedure period were reported. In addition, there was no evidence of myocardial injury on electrocardiography. After one month, none of the patients had class III or IV angina.
The authors conclude that PTMR is safe and effective, despite the lack of knowledge about the mechanism of transmyocardial revascularization. Long-term follow-up of the effects of PTMR is needed to assess the clinical benefits and compare them with those associated with a surgical approach.