Reproducibility of Transcranial Doppler ultrasound in the middle cerebral artery

Abstract Background Transcranial Doppler ultrasound remains the only imaging modality that is capable of real-time measurements of blood flow velocity and microembolic signals in the cerebral circulation. We here assessed the repeatability and reproducibility of transcranial Doppler ultrasound in healthy volunteers and patients with symptomatic carotid artery stenosis. Methods Between March and August 2017, we recruited 20 healthy volunteers and 20 patients with symptomatic carotid artery stenosis. In a quiet temperature-controlled room, two 1-h transcranial Doppler measurements of blood flow velocities and microembolic signals were performed sequentially on the same day (within-day repeatability) and a third 7–14 days later (between-day reproducibility). Levels of agreement were assessed by interclass correlation co-efficient. Results In healthy volunteers (31±9 years, 11 male), within-day repeatability of Doppler measurements were 0.880 (95% CI 0.726–0.950) for peak velocity, 0.867 (95% CI 0.700–0.945) for mean velocity, and 0.887 (95% CI 0.741–0.953) for end-diastolic velocity. Between-day reproducibility was similar but lower: 0.777 (95% CI 0.526–0.905), 0.795 (95% CI 0.558–0.913), and 0.674 (95% CI 0.349–0.856) respectively. In patients (72±11 years, 11 male), within-day repeatability of Doppler measurements were higher: 0.926 (95% CI 0.826–0.970) for peak velocity, 0.922 (95% CI 0.817–0.968) for mean velocity, and 0.868 (95% CI 0.701–0.945) for end-diastolic velocity. Similarly, between-day reproducibility revealed lower values: 0.800 (95% CI 0.567–0.915), 0.786 (95% CI 0.542–0.909), and 0.778 (95% CI 0.527–0.905) respectively. In both cohorts, the intra-observer Bland Altman analysis demonstrated acceptable mean measurement differences and limits of agreement between series of middle cerebral artery velocity measurements with very few outliers. In patients, the carotid stenoses were 30–40% (n = 9), 40–50% (n = 6), 50–70% (n = 3) and > 70% (n = 2). No spontaneous embolisation was detected in either of the groups. Conclusions Transcranial Doppler generates reproducible data regarding the middle cerebral artery velocities. However, larger studies are needed to validate its clinical applicability. Trial registration ClinicalTrial.gov (ID NCT 03050567), retrospectively registered on 15/05/2017

Supplementary Material for: Perioperative Strokes Following Surgical Correction of Mitral Valves: A Systematic Review and Meta-Analysis

<p><b><i>Objective:</i></b> The primary aim of this meta-analysis was to quantify the impact of perioperative strokes on stroke-related mortality after open mitral valve (MV) procedures were performed. <b><i>Methods:</i></b> An electronic search of the PubMed, Embase, and the Web of Science databases was performed to retrieve articles published up to December 2015, relevant to patients undergoing MV procedures. Data were extracted from the final list of 25 studies to calculate a summary OR for 30-day stroke-related mortality. <b><i>Results:</i></b> The stroke rate in the total sample population was 1.62% (73/4,498). The 30-day all-cause mortality rate was 3.51% (158/4,498). The percentage of total deaths caused by stroke was 6.87%. The summary OR of stroke-related mortality following MV procedures was estimated to be 7.22 (95% CI 4.13-12.63, <i>p</i> < 0.0001). A subgroup analysis was done for studies involving concomitant MV surgery and coronary artery bypass grafting. The summary estimate of the subgroup showed an OR of 8.508 (95% CI 1.552-46.622, <i>p</i> = 0.0136). <b><i>Conclusion:</i></b> Perioperative strokes following open MV procedures may be associated with more than 7 times greater odds of 30-day stroke-related mortality. They appear to be more commonly occurring than what is reported by current literature, making further studies investigating possible mechanisms and preventive measures a priority.</p