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

reasons for the lack of clinical improvement from aspiration thrombectomy might be that the current-generation aspiration catheter systems are not totally effective. The effectiveness of these catheters has been measured by improvement in surrogate markers of ischemia such as ST-segment elevat ion and myocardial blush grade. Based on these measurements, we know that the current aspiration catheters may lack precision, as they lead to improvement in reperfusion markers in only a minority of patients. This was supported by the fact that a visible thrombus was observed in only one-third of the cases in the aspirated blood from the coronary vasculature [6]. In addition, in their meta-analysis, Elgendy and colleagues showed that a myocardial blush grade of 2 was achieved in only roughly 60% of the patients undergoing aspiration thrombectomy, while resolution of ST-segment elevation was observed in approximately 70% of the patients [19]. These findings clearly demonstrate that our current aspiration catheters are not 100% effective. This may be due to the fundamental design of these catheters or the fact that these catheter systems are best suited only to aspiration of soft thrombus debris, while attempted aspiration of firm or large thrombi contributes to the aforementioned failure rates. Last, with no additional benefit of aspiration thrombectomy on clinical outcomes, one has to analyze if this adjunct therapy is really necessary. Adjunction of aspiration thrombectomy to PPCI may not be necessary, owing to modern advancements in the conventional PCI procedure itself. With the increased application of intravascular ultrasound (IVUS) technology, the sizing of stents during deployment into a thrombus has increased in accuracy. One could postulate that owing to IVUS-guided deployment, aspiration of thrombus debris prior to stenting may not be as necessary as once thought [28]. Another upcoming modality that may explain the minimal benefit yield of aspiration catheters is the use of M-guard stents. M-guard stents are part of an experimental device that is intended to decrease distal embolization [29]. During stent implantation, these mesh-covered stents provide adequate capture of thrombus between the outer layer of the stent and the intima layer of the coronary artery, which reduces distal embolization. With the use of these new-generation stents along with potent ADP receptor antagonists, as well as the IVUS technology, one can propose that the current technique of PPCI has already been perfected to a great extent. With that being said, it is natural to then understand why the addition of aspiration catheters may not yield any further benefits in cardiovascular or all-cause mortality.

Intracoronary thrombus is commonly found in patients with acute coronary syndromes (ACS) such as unstable angina or acute myocardial infarction (AMI) [1,2]. The histopathologic causes behind the formation and accumulation of thrombus are plaque erosion and subsequent rupture (Fig. 18.1A and B). The presence of thrombus is associated with an increased complication rate during and after percutaneous revascularization procedures [3e6]. In these acute clinical scenarios, the goal for primary and rescue PCI (percutaneous coronary intervention) is to provide expedient revascularization. These procedures aim at restoration of impaired antegrade coronary flow to a normal level, regaining of maximal patency of the ischemia/infarct-related vessel, enhancement of myocardial tissue perfusion, and achievement of maximal myocardial salvage. The utilization of manual aspiration catheters (i.e., non-power-sourced devices) has demonstrated a positive impact on myocardial perfusion and late clinical outcome [7]. Accordingly, the standard treatment approach to acute ischemic (thrombotic) syndromes is pharmacotherapy with aspirin, P2Y12 inhibitors, heparin, or glycoprotein IIb/IIIa receptor antagonists combined with manual aspiration [8,9]. Nevertheless, the reality of PCI in ACS is unsettling, as interventions quite frequently fall short of the desired outcome. The main cause of procedural failure is the underestimation of the volume of the underlying thrombus and insufficient removal. Consequently, a practical need to utilize a more powerful and capable technology for improved thrombus removal is highly recognized [10]. Hence, this chapter describes the challenges facing management of ACS associated with significant thrombus burden and includes a detailed presen­tation of the utilization of the main power-based mechanical thrombus removal devices.

Active changes in the composite architecture of thrombus oc cur in ACS [11] and, in particular, among patients sustaining STEMI (ST-segment elevation myocardial infarction) [12,13]. Early AMI thrombi are white, platelet rich, and friable. In contrast, in those patients arriving late (defined as more than 6 h) for care after the onset of STEMI the thrombus is red, as it has already become fibrin/erythrocyte rich with almost no platelets and exhibits rigidity [14]. From a practical revascularization perspective, most patients who experience ACS/STEMI develop thrombus; thus, compromised antegrade coronary flow can be antic ipated and, in case the thrombus is angiographically recognized as the culprit mechanism, a corresponding pharmacologic and accommodating mechanical thrombus removal strategy should be incorporated [15,16].