Chapter 10 - Laser debulking of complex and resistant atherosclerotic plaques in acute coronary syndromes

Abstract

Acute coronary syndrome (ACS) is a commonly used medical term that describes the cardiovascular clinical picture of patients who experience unstable angina or acute myocardial infarction. The preferred contemporary therapeutic strategy for patients presenting with this syndrome is percutaneous coronary intervention. Excimer laser is a reliable percutaneous revascularization established technology specifically applied for debulking and modification of atherosclerotic plaques that exhibit complex morphology and/or resistant features. The marked precision of the laser energy culminates in the transformation of these plaques into microscopic particles and the laser-generated acoustic shock waves mechanically disintegrate fibrin fibers within the adhering thrombus. This leads to efficient plaque vaporization and dissolution of the thrombus resulting in restoration of antegrade flow in the treated coronary arteries or in old bypass grafts. Importantly, the excimer laser strongly enhances an inhibitory effect on the aggregation kinetics of platelets adhering to the atherosclerotic plaque in patients with ACS. Clinical studies of various wavelength lasers in the setting of ACS repeatedly demonstrated expedient plaque recanalization and restoration of normal antegrade flow in the ischemia/infarct induced vessel. The utilization of laser requires that activation is initiated only after removal of the diagnostic contrast from the treated vessel by saline flash and emission of laser fluence is done using concomitant saline injections into the treated vessel. This avoids unwarranted amplification of laser-generated acoustic shock waves by the contrast dye. The shallow (35–50 μm) penetration depth of the excimer laser mandates slow catheter advancement of 0.2–0.5mm/s to optimize energy deposition and absorption into the lasered plaque. The marked precision of plaque vaporization and effective thrombus dissolution by the laser renders placement of distal protection devices unnecessary in most instances. Altogether, this laser can be successfully utilized in symptomatic patients who are in stable or in unstable hemodynamic conditions and in those with either normal or depressed left ventricular ejection fraction. The utilization of laser in complex and/or resistant atherosclerotic plaques and associated thrombus facilitates adjunct stenting. Thus, the interaction between laser emission and the absorbing bio tissues initiates an efficient plaque debulking process and, consequently, laser revascularization can be achieved with very high success rates and a considerable low rate of procedure-related complications.