Search

Purpose: To evaluate the feasibility of intravoxel incoherent motion (IVIM) for the measurement of diffusion and perfusion parameters in hyperacute strokes., Materials and Methods: An embolic ischemic model was established with an autologous thrombus in 20 beagles. IVIM imaging was performed on a 3.0 Tesla platform at 4.5 h and 6 h after embolization. Ten b values from 0 to 900 s/mm 2 were fitted with a bi-exponential model to extract perfusion fraction f, diffusion coefficient D, and pseudo-diffusion coefficient D*. Additionally, the apparent diffusion coefficient (ADC) was calculated using the mono-exponential model with all the b values. Statistical analysis was performed using the pairwise Student's t test and Pearson's correlation test., Results: A significant decrease in f and D was observed in the ischemic area when compared with those in the contralateral side at 4.5 h and 6 h after embolization (P < 0.01 for all). No significant difference was observed in D* between the two sides at either time point (P = 0.086 and 0.336, respectively). In the stroke area, f at 6 h was significantly lower than that at 4.5 h (P = 0.016). A significantly positive correlation was detected between ADC and D in both stroke and contralateral sides at 4.5 h and 6 h (P < 0.001 for both). Significant correlation between ADC and f was only observed in the contralateral side at 4.5 h and 6 h (P = 0.019 and 0.021, respectively)., Conclusion: IVIM imaging could simultaneously evaluate the diffusion and microvascular perfusion characteristics in hyperacute strokes., Level of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:550-556., (© 2016 International Society for Magnetic Resonance in Medicine.)

Background: Late-presenting ST-elevation myocardial infarction (STEMI) patients possess larger, more organized coronary thrombus leading to greater ventricular remodeling and arrhythmia despite angioplasty and pharmacological therapies. We hypothesized that myocardial injury would be reduced in late STEMI by proximal embolic protection (PEP)., Methods: 31 patients with first STEMI 12-24 hr after pain onset and TIMI 0-1 flow were treated with or without PEP (cohort design matched for age, gender, and infarct-related artery). Contrast-enhanced magnetic resonance determined myocardial function, area at risk, necrosis, salvaged myocardium, and arrythmogenic peri-infarct region. Clinical follow-up was performed., Results: Pain to balloon time was 18 hr (95% CI 15.5-21.2 h), and Q waves were present in 87%. Angioplasty was performed with PEP in 15 and without in 16. Left ventricular (LV) volumes and ejection fraction were similar (EF 46.9% vs. 49.0% without PEP, P = 0.9). Although myocardial necrosis was similar (32.5 vs. 37.3% of LV, P = 0.3), PEP improved microvascular obstruction (8.7 vs. 11.2% of LV, P = 0.02) salvaged myocardium (39.6% vs. 29.6% of area at risk, P = 0.001), and the peri-infarct region (20.9 vs. 29.6% of infarct, P < 0.0001). On multivariate analysis, the use of PEP was an independent predictor of decreased arrythmogenic peri-infarct region and greater myocardial salvage., Conclusion: In this pilot study, PEP improved myocardial salvage and the arrythmogenic peri-infarct region in late-presentation STEMI. Randomized trials are required to assess the clinical impact of improving salvaged myocardium and the peri-infarct region with PEP., (© 2010 Wiley-Liss, Inc.)

Embolization of athero-thrombotic material during primary percutaneous coronary intervention is a common cause of periprocedural complication. Methods developed to reduce embolization include thrombus aspiration, and distal protection. We report five cases of primary percutaneous intervention to coronary arteries that contain large amounts of thrombus, using a novel mesh covered stent. The mesh covering of the stent is designed such that it is theoretically able to ensnare thrombus and thus prevent distal migration of embolic material. In all cases, TIMI grade III flow was achieved at the end of the procedure, despite the extensive thrombus burden., (Copyright 2009 Wiley-Liss, Inc.)

During percutaneous coronary intervention for acute myocardial infarction, distal embolization of thrombus and plaque material often occurs, despite the use of thrombectomy and aspiration catheters. Large embolized thrombi can cause occlusion of distal coronary vessels for which angioplasty most often leads to no more than poor results. We describe the successful use of an aspiration catheter to treat distally embolized thrombus, to optimize coronary reperfusion therapy, and to improve salvage of myocardial tissue. We discuss the manifestation and incidence of distal embolization and show its clinical relevance.

Objectives: We detected embolic particles liberated from plaque during percutaneous coronary intervention (PCI) as high-intensity transient signals (HITS) with a Doppler guidewire and studied their impact on coronary flow dynamics and the myocardium in patients with stable angina pectoris., Background: These embolic particles during PCI may cause myocardial injury. However, this was difficult to confirm because it was impossible to detect embolic particles., Methods: We performed balloon angioplasty followed by stenting in 31 patients while monitoring coronary flow velocity. After PCI, we measured average peak velocity at baseline and after infusion of adenosine 5'-triphosphate to calculate coronary flow velocity reserve (CFVR) and coronary resistance index (CRI). In patients with PCI to the left coronary artery (n = 21), we calculated relative CFVR as the ratio of CFVR in the target vessel to that in the reference vessel. We measured cardiac troponin T (cTnT) the day after PCI., Results: HITS were detected in 27 (87%) of 31 patients and the majority were observed after stenting. The total number of HITS was correlated with CRI (r = 0.36, P = 0.049) or relative CFVR (r = 0.65, P = 0.0036) but not with CFVR (r = 0.048, P = 0.82). Thirteen patients showed elevated cTnT (range, 0.05-0.31 ng/ml) and the total number of HITS was greater in those with elevated cTnT than in those without elevated cTnT (24 +/- 9 vs. 10 +/- 7, P = 0.0007)., Conclusions: Embolic particles are frequently observed during PCI to stable plaque and the majority are liberated after stenting. There appears to be a quantitative relationship between amounts of HITS and coronary microvessel dysfunction and minor myocardial injury., ((c) 2006 Wiley-Liss, Inc.)

It is generally believed that alterations in perfusion which endanger a free flap or replant are directly related to thrombus formation and obstruction of blood flow at the anastomotic site. Recent experimental work in our laboratory suggests that the presence of platelet emboli downstream in the microcirculation might be responsible at least in part for postoperative perturbations in perfusion. To determine whether changes in tissue perfusion can occur in the absence of corresponding changes in anastomotic patency we studied microvascular blood flow in the exposed rat cremaster flap model. We made continuous measurements of both anastomotic patency and downstream microcirculatory perfusion following small vessel repair. Using this approach we found that during one hour after clamp release and reperfusion in the 10 animals studied, pedicle artery blood pressure, which indicates pedicle patency in this model, was functionally normal 97% +/- 2 of the time while blood flow in the downstream tissue (cremaster) remained normal an average of only 65% +/- 7 of the time. In most cases these flow alterations were associated with the presence of visible platelet emboli in the microcirculation. From these studies we conclude that when flap perfusion failure temporarily occurs, a microsurgeon must consider not only the anastomosis but also the downstream microcirculation when searching for a possible cause.