Spyros N. Vasdekis

Velocity Criteria for Intracranial Stenosis Revisited An International Multicenter Study of Transcranial Doppler and Digital Subtraction Angiography

Background and Purpose— Intracranial atherosclerotic disease is associated with a high risk of stroke recurrence. We aimed to determine accuracy of transcranial Doppler screening at laboratories that share the same standardized scanning protocol. Methods— Patients with symptoms of cerebral ischemia were prospectively studied. Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) criteria were used for identification of ≥50% stenosis. We determined velocity cutoffs for ≥70% stenosis on digital subtraction angiography by Warfarin–Aspirin Symptomatic Intracranial Disease criteria and evaluated novel stenotic/prestenotic ratio and low-velocity criteria. Results— A total of 102 patients with intracranial atherosclerotic disease (age 57±13 years; 72% men; median National Institutes of Health Stroke Scale 3, interquartile range 6) provided 690 transcranial Doppler/digital subtraction angiography vessel pairs. On digital subtraction angiography, ≥50% stenosis was found in 97 and ≥70% stenosis in 62 arteries. Predictive values for transcranial Doppler SONIA criteria were similar (P>0.9) between middle cerebral artery (sensitivity 78%, specificity 93%, positive predictive value 73%, negative predictive value 94%, and overall accuracy 90%) and vertebral artery/basilar artery (69%, 98%, 88%, 93%, and 92%). As a single velocity criterion, most sensitive mean flow velocity thresholds for ≥70% stenosis were: middle cerebral artery >120 cm/s (71%) and vertebral artery/basilar artery >110 cm/s (55%). Optimal combined criteria for ≥70% stenosis were: middle cerebral artery >120 cm/s, or stenotic/prestenotic ratio ≥3, or low velocity (sensitivity 91%, specificity 80%, receiver operating characteristic 0.858), and vertebral artery/basilar artery >110 cm/s or stenotic/prestenotic ratio ≥3 (60%, 95%, 0.769, respectively). Conclusions— At laboratories with a standardized scanning protocol, SONIA mean flow velocity criteria remain reliably predictive of ≥50% stenosis. Novel velocity/ratio criteria for ≥70% stenosis increased sensitivity and showed good agreement with invasive angiography.

A multilayer stent in the aorta may not seal the aneurysm, thereby leading to rupture

The multilayer stents are occasionally used for the treatment of complicated aortic aneurysms, including thoracoabdominal aneurysms. No aneurysm-related mortality among patients treated with this technique has been described in the literature to date. We describe a case of rupture of an aortic aneurysm previously treated with a multilayer stent.

Real-time Validation of Transcranial Doppler Criteria in Assessing Recanalization During Intra-arterial Procedures for Acute Ischemic Stroke An International, Multicenter Study

Background and Purpose— We sought to evaluate the diagnostic accuracy of ultrasound criteria for recanalization during real-time transcranial Doppler monitoring of intra-arterial reperfusion procedures in acute ischemic stroke patients in an international, multicenter study. Methods— Consecutive acute ischemic stroke patients with proximal intracranial occlusions underwent intra-arterial reperfusion procedures with simultaneous real-time transcranial Doppler monitoring at 3 tertiary-care stroke centers. Residual flow signals at the site of angiographically confirmed occlusions were monitored at a constant transtemporal insonation angle using a standard head-frame. Recanalization was assessed simultaneously by digital subtraction angiography and ultrasound using thrombolysis in myocardial infarction and thrombolysis in brain ischemia (TIBI) criteria, respectively. Independent readers blinded to digital subtraction angiography performed validation of TIBI flow grades. The interrater reliability for assessment of TIBI grades was investigated. Results— We evaluated time-linked real-time digital subtraction angiography transcranial Doppler images from 96 diagnostic digital subtraction angiography runs during intra-arterial reperfusion procedures in 62 acute ischemic stroke patients (mean age, 59±17 years; 58% men; median baseline National Institutes of Health Stroke Scale score, 18 [interquartile range 12–21]; median time from symptom onset to intra-arterial procedure initiation, 240 minutes [interquartile range 163–308]). The interrater reliability for evaluation of TIBI grades and assessment of recanalization was good (Cohen &kgr;: 0.838 and 0.874, respectively; P<0.001). Compared with angiography, transcranial Doppler had the following accuracy parameters for detection of complete recanalization (TIBI 4 and 5 versus thrombolysis in myocardial infarction 3, flow grades): sensitivity, 88% (95% confidence interval, 72%–96%); specificity, 89% (79%–95%); positive predictive value, 81% (65%–91%); negative predictive value, 93% (84%–98%); and overall accuracy 89% (80%–94%). Conclusions— At laboratories with high-interrater reliability, TIBI criteria can accurately predict brain recanalization in real time as compared with thrombolysis in myocardial infarction angiographic scores.

Prevalence of Symptomatic Intracranial Atherosclerosis in Caucasians: A Prospective, Multicenter, Transcranial Doppler Study

There are limited data available regarding symptomatic intracranial atherosclerosis (SIA) prevalence in Caucasians. We sought to investigate SIA prevalence among Caucasian patients hospitalized with acute cerebral ischemia (ACI) in a prospective, multicenter Transcranial Doppler sonography (TCD) study.

Statin pretreatment is associated with better outcomes in large artery atherosclerotic stroke

Objective: Even though statin pretreatment is associated with better functional outcomes and lower risk of mortality in acute ischemic stroke, there are limited data evaluating this association in acute ischemic stroke due to large artery atherosclerosis (LAA), which carries the highest risk of early stroke recurrence. Methods: Consecutive patients with acute LAA were prospectively evaluated from 7 tertiary-care stroke centers during a 3-year period. Statin pretreatment, demographics, vascular risk factors, and admission and discharge stroke severity were recorded. The outcome events of interest were neurologic improvement during hospitalization (quantified as the relative decrease in NIH Stroke Scale score at discharge in comparison to hospital admission), favorable functional outcome (FFO) (defined as modified Rankin Scale score of 0–1), recurrent stroke, and death at 1 month. Statistical analyses were performed using univariable and multivariable Cox regression models adjusting for potential confounders. All analyses were repeated following propensity score matching. Results: Statin pretreatment was documented in 192 (37.2%) of 516 consecutive patients with LAA (mean age: 65 ± 13 years; 60.8% men; median NIH Stroke Scale score: 9 points, interquartile range: 5–18). Statin pretreatment was associated with greater neurologic improvement during hospitalization and higher rates of 30-day FFO in unmatched and matched (odds ratio for FFO: 2.44; 95% confidence interval [CI]: 1.07–5.53) analyses. It was also related to lower risk of 1-month mortality and stroke recurrence in unmatched and matched analyses (hazard ratio for recurrent stroke: 0.11, 95% CI: 0.02–0.46; hazard ratio for death: 0.24, 95% CI: 0.08–0.75). Conclusion: Statin pretreatment in patients with acute LAA appears to be associated with better early outcomes regarding neurologic improvement, disability, survival, and stroke recurrence.

Safety of transcranial Doppler ‘bubble study’ for identification of right to left shunts: an international multicentre study

Background and purpose A recent retrospective study using an online list service established by the American Academy of Neurology has suggested that ischaemic cerebrovascular events may occur in patients who undergo ‘bubble studies’ (BS) with either transcranial Doppler (TCD) or transoesophageal echocardiography (TOE). The safety of TCD-BS for right to left shunt (RLS) identification was evaluated prospectively in an international multicentre study. Methods Consecutive patients with cerebral ischaemia (ischaemic stroke or transient ischaemic attack (TIA)) were screened for potential ischaemic cerebrovascular events following injection of microbubbles during TCD-BS for identification of RLS at three tertiary care stroke centres. TCD-BS was performed according to the standardised International Consensus Protocol. TOE-BS was performed in selected cases for confirmation of TCD-BS. Results 508 patients hospitalised with acute cerebral ischaemia (mean age 46±12 years, 59% men; 63% ischaemic stroke, 37% TIA) were investigated with TCD-BS within 1 week of ictus. RLS was identified in 151 cases (30%). TOE-BS was performed in 101 out of 151 patients with RLS identified on TCD-BS (67%). It was positive in 99 patients (98%). The rate of ischaemic cerebrovascular complications during or after TCD-BS was 0% (95% CI by the adjusted Wald method: 0–0.6%). Structural cardiac abnormalities were identified in 38 patients, including atrial septal aneurysm (n=23), tetralogy of Fallot (n=1), intracardiac thrombus (n=2), ventricular septal defect (n=3) and atrial myxoma (n=1). Conclusion TCD-BS is a safe screening test for identification of RLS, independent of the presence of cardiac structural abnormalities.

Safety of early endarterectomy in patients with symptomatic carotid artery stenosis: an international multicenter study

Although the latest recommendations suggest that carotid endarterectomy (CEA) should be performed in symptomatic carotid artery stenosis (sCAS) patients within 2 weeks of the index event, only a minority of patients undergo surgery within the recommended time‐frame. The aim of this international multicenter study was to prospectively evaluate the safety of early CEA in patients with sCAS in everyday clinical practice settings.

Cerebrovascular reacivity assessment in patients with carotid artery disease: a combined TCD and NIRS study.

Transcranial Doppler (TCD) and near‐infrared spectroscopy (NIRS) are two noninvasive diagnostic tools that have been shown to evaluate cerebral vasomotor reactivity by measuring changes in mean cerebral blood flow velocities (MCBFV) of proximal intracranial arteries and absolute brain‐tissue oxygen‐saturation (TOS) in microcirculation, respectively, during hemodynamic challenge. We evaluated the potential correlation between TCD and NIRS measurements of vasomotor reactivity (VMR) in patients with carotid artery disease (CARAD).

The role of remote ischemic preconditioning in the treatment of atherosclerotic diseases

Remote ischemic preconditioning (RIPC) is the application of a transient and brief ischemic stimulus to a distant site from the organ or tissue that is afterward exposed to injury ischemia, and has been found to reduce ischemia–reperfusion injury (IRI) in various animal models. RIPC appears to offer two distinct phases of endothelial IRI protection, which are presumably mediated through neuronal and humoral pathways.

Flow-Diverting Multilayer Stents: A Promising but Questionable Solution for Aortic Pathologies:

In this issue of the JEVT, Sultan and Hynes review 55 patients with various aortic pathologies treated with the Cardiatis multilayer flow modulator or flow-diverting stents by a variety of surgeons and interventionists in 11 countries. Despite the fact that this is from a registry and not a properly conducted trial, the data and conclusions are of significant importance. This is the largest report to date with regard to the use of these stents in aortic pathologies. Since the first reported extracranial use of a flow-diverting stent in aneurysmal disease in 2008, sporadic reports have appeared in the literature with regard to their use in aortic pathologies. According to the study, extraordinarily exceptional results can exist with the use of the multilayer stent in thoracoabdominal aneurysms and type B aortic dissections up to 1-year follow-up: zero conversion to open surgery, zero admission to intensive care units postoperatively, zero paraplegia, zero visceral/renal artery occlusions, zero major perioperative bleeding (.20% of blood volumes), and zero 30-day mortality. Would this be the situation with the mid and long-term results as well, there would be almost no need for any other treatment for these extremely hazardous pathologies. But, is this method really that good? The hypothesis of aneurysm thrombosis using a low porosity bare metal stent was first described about two decades ago. Geremia et al. had observed that a metallic stent bridging an aneurysm sac might alter the flow pattern within the aneurysm, thereby promoting thrombus formation and aneurysm occlusion. At the same time, Piquet et al. described treatment of aneurysms utilizing a stent-like device that combined both metal and fabric, the so-called ‘‘coknit.’’ In patients treated with the coknit, thrombosis had been observed, while the inferior mesenteric and all the non-occluded lumbar arteries were patent. Similarly, the multilayer flow modulator stent is a bare stent system. It is structured with two interconnected superimposed layers that achieve low intra-stent porosity. A computational fluid dynamics study indicates that a stent with an overall porosity of 50% to 70% significantly reduces the inflow rate into the aneurysm sac by improving the laminar flow in the main artery and its branches. Theoretically, in an aneurysm with branches, the stent redirects the flow toward the ostia of the side branches, creating a kind of suction effect to the aneurysm itself. This allows a pressure decrease within the aneurysm sac, stasis, and formation of organized thrombus. However, this is a two-faced coin. Conflicting research data exist in the literature. Michel and colleagues have proposed that blood supply within the intraluminal aneurysm