Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3720_Библиотеки_им_академика_М_И_Перельмана

Clinically, the excimer laser is a useful interventional tool for targeted thrombus removal strategy [60,80]. Patients who sustain AMI and continue to experience chest pain with unrelieved ischemia are frequently in unsta ble hemodynamic condition. These patients commonly present following initial failure to respond to throm bolytic pharmacotherapy (defined as continuous chest pain and/or no resolution of the abnormal ST segment on the ECG) or have contraindications to these medications. The initial experience with laser application in AMI was gained by utilization of the holmium:YAG solid state, pulsed-wave midinfrared laser [81]. Then interest in treating these patients shifted to the ultraviolet, pulsed-wave excimer laser. This stems from recognition of this laser’s ability to simultaneously treat plaque and accompanying thrombus [82e84]. Figs. 18.9, and 18.10 demonstrate the excimer laser application in atherosclerotic/thrombotic lesions in the context of AMI and unstable angina. The thrombus dissolution extent and impact of the excimer laser was thoroughly studied in the CARMEL international multicenter study [23]. This trial enrolled 151 real-world AMI patients with continuous chest pain and ischemia in the presence of either STEMI or non-STEMI, including late presentation, cardio­genic shock (13%), and failed thrombolytic therapy (11%) and those with contraindications for the pharmacotherapy (17%). The target vessel was a native coronary vessel in 79% and an old saphenous vein bypass graft in 21%. The entire cohort underwent quantitative and statistical analyses by independent core laboratories and the results proved that despite the presence of compromised hemodynamics and a heavy thrombus burden in as many as 65% of the patients, laser success was achieved in 95%, angiographic success in 97% and procedural success in 91%. A baseline TIMI 0 flow of 1.2  1.1 increased to 2.8  0.5 with the laser energy and was followed by final a TIMI flow of 3.0  0.2 (P < .001 vs. baseline) with adjunct stenting. Distal embolization occurred in only 2%, no reflow in 3%, device-induced small dissection was observed in 4%, and a small perforation in 0.6%. Total major adverse coronary event (MACE) was relatively low at 13%. The two most important findings of the CARMEL study were the following: (1) Maximal laser thrombus removal effect was directly proportional to the basel ine thrombus burden, i.e., the larger the initial thrombus burden at the target lesion, the more effective and the higher gain for the laser-induced dissolution (Fig. 18.11). Intriguingly, multivariable regression analysis of the CARMEL study did not identify thrombus as a predictor of PCI failure, while the opposite holds true with any other interventional device. (2) A subgroup analysis identified very specific laser gain in patients with late presentation, who typically carry a heavy thrombus burden and unstable hemodynamic condition [85]. Altogether, the CARMEL study provided the first quantitative evidence of the considerable benefit of a dedicated power-sourced mechanical thrombectomy device in a thrombus removal strategy and, in particular, in patients sustaining AMI (Fig. 18.12). Thus, the role of the excimer laser in revascularization of thrombus-containing lesions has been established with the growing recognition of the debulking ability to create favorable vessel lumen morphology which, in turn, facilitates stent deployment and long-term results [86].

The mechanical power-based rheolytic thrombectomy system (AngioJet, Boston Scientific, Boston, MA, USA) (Fig. 18.15 ), is a US FDA-approved device for targeted mechanical extraction of thrombus from coronary and peripheral vasculature [96]. The concept of powerful mechanical thrombus extraction was first promoted by the introduction of the first-generation power-sou rced thrombectomy transluminal extraction catheter device, which was used for treatment of significant thrombus burden [97,98]. The principle of activation for the rheolytic thrombectomy is based on the creation of saline jets inside the catheter, which travel backward from the tip at very high speed, creating a negative-pressure zone by the Venturi effect. Side holes along the catheter’s tip optimize fluid flow and draw the thrombus into the catheter for fragmentation and removal by suction into a collecting bag (Fig. 18.16). A second-generation AngioJet, the ULTRA, was introduced several years ago, featuring automated, rapid setup and support for a wide range of catheters. Multiple rapid­exchange 4- or 5-Fr flexible catheters (Fig. 18.17) are available for various target vessels, including native coronary arteries, old saphenous vein grafts (SVGs), and peripheral arter ies. Fig. 18.18 demonstrates the gradual steps taken along a unique revascularization technique aimed at recanalization and revascularization of totally occluded SVGs, which cause ischemic myocardium. We intr oduced this technique and termed it “SVG sculpturing.” Other power-based thrombus removal technologies can be incorporated with the rheolytic thrombectomy along with SVG sculpturing. Another advantage of utilization of the rheolytic thrombectomy is a unique device function termed “power spray,” which infuses tPA or other thrombolytic agents intraluminally directly onto the thrombus during revascularization. This offers a com­bined pharmacologic thrombolytic effect with powerful mechanical extraction, a synergistic strategy aptly termed “power thrombectomy” [10]. Proper thrombectomy technique incorporating slow antegrade advancement of the AngioJet catheter eliminates in most cases the need for a temporary pacemaker protection against device-induced bradycardia. However, some interventionalists still recommend standby or even active pacing for patients requiring thrombectomy of a major epicardial coronary vessel and in those with limited myocardial reserve.

The AngioJet’s ability to treat large thrombus burden in STEMI patients and provide more effective myocardial perfusion than that obtained with standard balloon and adjunct stenting has been well documented [99,100]. In the FAST (Florence Appraisal Study of Rheolytic Thrombectomy) study, the AngioJet was used to treat 116 AMI patients with extensive thrombus load, leading to significant improvements in perfusion compared with a control group with similar thrombus burden who received standard PCI [101]. The in-hospital MACE rate for the AngioJet was relatively low at 8%. Further evidence of the excellent safety profile of the AngioJet has been repeatedly reported [102,103]. Then the Thor­axcenter group elegantly demonstrated that AngioJet thrombectomy is a significant, independent predictor of reduced risk for stent thrombosis and MACE specifically when applied for removal of large thrombus burden in STEMI patients [25]. However, the concept of thrombus extraction suffered a significant setback when negative results from the AIMI (AngioJet in Myocardial Infarction) multicenter study were published [104]. In perspective, the unfavorable findings could have been predicted because of the poor study design that did not require the angiographic presence of a thrombus for enrollment. Moreover, the study’s rigid protocol mandated passive advancement of the AngioJet catheter across the thrombus and the entire length of the target vessel before activation at the distal end of the vessel with retrograde thrombectomy, neces­sitating recrossing of the thrombus. Later on, with the intention to address questions and reservations concerning the AIMI