Leaflet thrombosis following transcatheter aortic valve implantation

BACKGROUND

Transcatheter aortic valve implantation (TAVI) is increasingly being offered to high-risk patients with symptomatic aortic valve stenosis. Recent reports have suggested a high incidence of subclinical leaflet thrombosis following bioprosthestic aortic valve replacement. We report the frequency and clinical presentation of leaflet thrombosis identified by cardiac CT in patients referred for follow-up contrast enhanced CT angiography following TAVI.

METHODS

91 consecutive patients referred for follow-up contrast-enhanced CT angiography following TAVI were screened for inclusion in this analysis. Out of these, 13 patients were excluded. All CT examinations were performed using a 2nd or a 3rd generation dual-source system (Somatom Definition Flash/Force, Forchheim, Germany). In all patients, retrospectively ECG-gated spiral acquisition with tube modulation was performed to allow for assessment of leaflet motion. All prostheses were analyzed for presence of leaflet thrombosis defined as hypo-attenuated leaflet thickening with or without leaflet restriction. Post-procedural antithrombotic regimen as well as symptom status was documented in all patients.

RESULTS

78 consecutive patients (35 males, 81 ± 4 years) were analyzed. TAVI had been performed in all patients (76 transfemoral access, 2 transapical access) with either balloon-expandable prostheses (4 Sapien XT, 64 Sapien 3) or self-expandable prostheses (5 SJM Portico, 5 Symetis Acurate). Follow-up CT angiography was performed at a median of 4 months following index procedure (Interquartile range 1 month). Leaflet thrombosis was detected in 18 patients (23%, 14 Sapien 3, 1 Sapien XT, 2 SJM Portico, 1 Symetis Acurate). In patients with leaflet thickening on CT, only 11% were on either oral anticoagulation or new oral anticoagulants versus 50% for patients with no leaflet thickening (p 0.002). In patients with leaflet thrombosis, 3 leaflets were affected in 5 patients, 2 leaflets in 5 patients and in 8 patient only 1 leaflet was affected. Clinical symptoms (angina, dyspnea or both) were reported in 2/18 patients with leaflet thrombosis (11%) and in both patients a significant increase of the mean echocardiographic gradient over the prosthesis was documented. The peak and mean echocardiographic gradients obtained at the day of CT examination was significantly higher in symptomatic patients versus asymptomatic patients (peak 46 ± 7 vs. 23 ± 11 mmHg, mean 29 ± 7 vs. 12 ± 6 mmHg, p = 0.01 and 0.002, respectively). Follow-up CT was available for 4 patients with complete resolution of the hypo-attenuated leaflet thickening following treatment.

CONCLUSION

Leaflet thrombosis following TAVI is a relatively frequent finding in patients referred for contrast enhanced CT angiography following TAVI. In the majority of patients it follows a subclinical course and is substantially more frequent in individuals who are not on oral anticoagulation. However, in patients with relevant increase in prosthetic gradients, symptomatic presentations are possible.

Microindentation - a tool for measuring cortical bone stiffness? A systematic review

Objectives

Microindentation has the potential to measure the stiffness of an individual patient’s bone. Bone stiffness plays a crucial role in the press-fit stability of orthopaedic implants. Arming surgeons with accurate bone stiffness information may reduce surgical complications including periprosthetic fractures. The question addressed with this systematic review is whether microindentation can accurately measure cortical bone stiffness.

Methods

A systematic review of all English language articles using a keyword search was undertaken using Medline, Embase, PubMed, Scopus and Cochrane databases. Studies that only used nanoindentation, cancellous bone or animal tissue were excluded.

Results

A total of 1094 abstracts were retrieved and 32 papers were included in the analysis, 20 of which used reference point indentation, and 12 of which used traditional depth-sensing indentation. There are several factors that must be considered when using microindentation, such as tip size, depth and method of analysis. Only two studies validated microindentation against traditional mechanical testing techniques. Both studies used reference point indentation (RPI), with one showing that RPI parameters correlate well with mechanical testing, but the other suggested that they do not.

Conclusion

Microindentation has been used in various studies to assess bone stiffness, but only two studies with conflicting results compared microindentation with traditional mechanical testing techniques. Further research, including more studies comparing microindentation with other mechanical testing methods, is needed before microindentation can be used reliably to calculate cortical bone stiffness.

Cite this article: M. Arnold, S. Zhao, S. Ma, F. Giuliani, U. Hansen, J. P. Cobb, R. L. Abel, O. Boughton. Microindentation – a tool for measuring cortical bone stiffness? A systematic review. Bone Joint Res 2017;6:542–549. DOI: 10.1302/2046-3758.69.BJR-2016-0317.R2.

International cancer seminars: a focus on esophageal squamous cell carcinoma

The International Agency for Research on Cancer (IARC) and the US National Cancer Institute (NCI) have initiated a series of cancer-focused seminars [Scelo G, Hofmann JN, Banks RE et al. International cancer seminars: a focus on kidney cancer. Ann Oncol 2016; 27(8): 1382-1385]. In this, the second seminar, IARC and NCI convened a workshop in order to examine the state of the current science on esophageal squamous cell carcinoma etiology, genetics, early detection, treatment, and palliation, was reviewed to identify the most critical open research questions. The results of these discussions were summarized by formulating a series of 'difficult questions', which should inform and prioritize future research efforts.

Fully automated stroke tissue estimation using random forest classifiers (FASTER)

Several clinical trials have recently proven the efficacy of mechanical thrombectomy for treating ischemic stroke, within a six-hour window for therapy. To move beyond treatment windows and toward personalized risk assessment, it is essential to accurately identify the extent of tissue-at-risk ("penumbra"). We introduce a fully automated method to estimate the penumbra volume using multimodal MRI (diffusion-weighted imaging, a T2w- and T1w contrast-enhanced sequence, and dynamic susceptibility contrast perfusion MRI). The method estimates tissue-at-risk by predicting tissue damage in the case of both persistent occlusion and of complete recanalization. When applied to 19 test cases with a thrombolysis in cerebral infarction grading of 1-2a, mean overestimation of final lesion volume was 30 ml, compared with 121 ml for manually corrected thresholding. Predicted tissue-at-risk volume was positively correlated with final lesion volume ( p < 0.05). We conclude that prediction of tissue damage in the event of either persistent occlusion or immediate and complete recanalization, from spatial features derived from MRI, provides a substantial improvement beyond predefined thresholds. It may serve as an alternative method for identifying tissue-at-risk that may aid in treatment selection in ischemic stroke.

Impact of Anesthesia on the Outcome of Acute Ischemic Stroke after Endovascular Treatment with the Solitaire Stent Retriever

BACKGROUND AND PURPOSE

General anesthesia during endovascular treatment of acute ischemic stroke may have an adverse effect on outcome compared with conscious sedation. The aim of this study was to examine the impact of the type of anesthesia on the outcome of patients with acute ischemic stroke treated with the Solitaire stent retriever, accounting for confounding factors.

MATERIALS AND METHODS

Four-hundred one patients with consecutive acute anterior circulation stroke treated with a Solitaire stent retriever were included in this prospective analysis. Outcome was assessed after 3 months by the modified Rankin Scale.

RESULTS

One-hundred thirty-five patients (31%) underwent endovascular treatment with conscious sedation, and 266 patients (69%), with general anesthesia. Patients under general anesthesia had higher NIHSS scores on admission (17 versus 13, P < .001) and more internal carotid artery occlusions (44.6% versus 14.8%, P < .001) than patients under conscious sedation. Other baseline characteristics such as time from symptom onset to the start of endovascular treatment did not differ. Favorable outcome (mRS 0-2) was more frequent with conscious sedation (47.4% versus 32%; OR, 0.773; 95% CI, 0.646-0.925; P = .002) in univariable but not multivariable logistic regression analysis (P = .629). Mortality did not differ (P = .077). Independent predictors of outcome were age (OR, 0.95; 95% CI, 0.933-0.969; P < .001), NIHSS score (OR, 0.894; 95% CI, 0.855-0.933; P < .001), time from symptom onset to the start of endovascular treatment (OR, 0.998; 95% CI, 0.996-0.999; P = .011), diabetes mellitus (OR, 0.544; 95% CI, 0.305-0.927; P = .04), and symptomatic intracerebral hemorrhage (OR, 0.109; 95% CI, 0.028-0.428; P = .002).

CONCLUSIONS

In this single-center study, the anesthetic management during stent retriever thrombectomy with general anesthesia or conscious sedation had no impact on the outcome of patients with large-vessel occlusion in the anterior circulation.

Diagnostic value of prehospital ECG in acute stroke patients

Objective:

To investigate the diagnostic yield of prehospital ECG monitoring provided by emergency medical services in the case of suspected stroke.

Methods:

Consecutive patients with acute stroke admitted to our tertiary stroke center via emergency medical services and with available prehospital ECG were prospectively included during a 12-month study period. We assessed prehospital ECG recordings and compared the results to regular 12-lead ECG on admission and after continuous ECG monitoring at the stroke unit.

Results:

Overall, 259 patients with prehospital ECG recording were included in the study (90.3% ischemic stroke, 9.7% intracerebral hemorrhage). Atrial fibrillation (AF) was detected in 25.1% of patients, second-degree or greater atrioventricular block in 5.4%, significant ST-segment elevation in 5.0%, and ventricular ectopy in 9.7%. In 18 patients, a diagnosis of new-onset AF with direct clinical consequences for the evaluation and secondary prevention of stroke was established by the prehospital recordings. In 2 patients, the AF episodes were limited to the prehospital period and were not detected by ECG on admission or during subsequent monitoring at the stroke unit. Of 126 patients (48.6%) with relevant abnormalities in the prehospital ECG, 16.7% received medical antiarrhythmic therapy during transport to the hospital, and 6.4% were transferred to a cardiology unit within the first 24 hours in the hospital.

Conclusions:

In a selected cohort of patients with stroke, the in-field recordings of the ECG detected a relevant rate of cardiac arrhythmia. The results can add to the in-hospital evaluation and should be considered in prehospital care of acute stroke.

Dual source computed tomography based analysis of stent performance, its association with valvular calcification and residual aortic regurgitation after implantation of a balloon-expandable transcatheter heart valve

Objectives

The aim of this study was to investigate the mutual influence of valvular calcifications and transcatheter aortic valve stent geometry during and after implantation of a balloon-expandable SAPIEN ® /SAPIEN XT ® prostheses. Aortic valve calcification has been linked with adverse complications after transcatheter aortic valve implantation (TAVI). However, little is known about the fate of the calcifications after TAVI as well as its influence on transcatheter heart valve geometry.

Methods

Thirty one patients underwent cardiac dual source computed tomography (DSCT) before and after a TAVI with the Edwards SAPIEN/SAPIEN XT ® prostheses. Detailed DSCT image analysis was performed with Mimics ® and 3Matic ® (both Materialise, Leuven, Belgium).

Results

Implanted stents reached an average degree of expansion of 84% and achieved good circularity despite the presence of fairly oval native annuli and a heterogeneous degree of valvular calcification. Both, the degree of stent expansion and the degree of stent eccentricity were inversely related to the degree of oversizing, but independent of the degree of valvular calcification and native annular ovality. Visualization of the position of calcific debris before and after TAVI showed that calcifications were shifted upwards and outwards as a consequence of the implantation procedure. The degree of stent eccentricity was related to residual aortic regurgitation grade ≥2.

Conclusions

The SAPIEN ® /SAPIEN XT ® prostheses achieved good degrees of stent expansion and circularity regardless of the morphology of the landing zone. Increased stent ovality was associated with an elevated risk for aortic regurgitation. The total calcification volume, degree of annular ovality and stent expansion were not associated with residual AR.

Improving fortification with weekly analysis of human milk for VLBW infants

OBJECTIVE

To track individual mother's macronutrient variability in preterm human milk (HM) over 6 weeks of lactation.

STUDY DESIGN

This was a prospective, observational study of mother's own milk from women who delivered a very low birth weight infant (<1500 g). A single, random maternal breast milk sample was collected and analyzed weekly for 6 consecutive weeks. Analysis was by mid-infrared spectroscopy.

RESULTS

Twenty women consented to provide at least one milk sample. Fat, protein and energy content varied widely among mothers and by week of lactation. Energy content ranged from 9.5 to 30.4 kcal oz^-1 across the study period. Twenty-five percent of all samples had an energy content <17 kcal oz^-1. Protein content ranged from 1.1 to 2.8 g dl^-1 in the first week. Sixty-three percent of all samples had a protein content <1.5 g dl^-1. Fat and energy showed trends of increasing concentrations, whereas protein showed the expected decline over time. Lactose showed little variability by woman or by week of lactation.

CONCLUSION

HM fat and protein content varied widely by individual woman over time. Week-to-week variability in fat and protein can impact growth. The ability to analyze HM is helpful to improve fortification of HM.

Cerebrovascular Response to Repetitive Visual Stimulation in Interictal Migraine with Aura

Cortical hypersensitivity and absent habituation to different stimuli have been observed in migraine patients. These features might also be transmitted to the cerebral vasoreactivity, but results are conflicting so far. Transcranial Doppler ultrasound (TCD) was used to assess cerebral blood flow velocity (CBFV) changes in the middle (MCA) and posterior cerebral arteries (PCA) in relation to repetitive checkerboard visual stimulation. Stimulation consisted of 10 consecutive cycles, each comprising 10 s stimulation and 10 s rest. TCD recordings were analysed using stimulus-related averaging algorithm. Data of 19 interictal migraineurs with aura were compared to those of 19 headache-free healthy volunteers. The CBFV increase in PCA and in MCA during visual stimulation was significantly larger and steeper in migraineurs than in controls ( P = 0.017 and P = 0.005). The response in PCA remained stable over the 10 stimulation cycles, both in migraineurs and in controls. The response in MCA was stable only in migraineurs. In controls it decreased over the last 5 stimulation cycles compared with the first 5 cycles ( P = 0.04). Migraineurs with aura exhibit a larger cerebrovascular response to repetitive visual stimulation compared to headache-free subjects. A reduced adaptation to environmental stimuli in migraine is suggested, since there was no habituation in migraineurs in contrast to healthy controls.

Global patterns of cardia and non-cardia gastric cancer incidence in 2012

OBJECTIVE

Globally, gastric cancer incidence shows remarkable international variation and demonstrates distinct characteristics by the two major topographical subsites, cardia (CGC) and non-cardia (NCGC). Because global incidence estimates by subsite are lacking, we aimed to describe the worldwide incidence patterns of CGC and NCGC separately.

DESIGN

Using Cancer Incidence in Five Continents Volume X (CI5X), we ascertained the proportions of CGC and NCGC by country, sex and age group (<65 and ≥65 years). These derived proportions were applied to GLOBOCAN 2012 data to estimate country-specific age-standardised CGC and NCGC incidence rates (ASR). Regional proportions were used to estimate rates for countries not included in CI5X.

RESULTS

According to our estimates, in 2012, there were 260,000 cases of CGC (ASR 3.3 per 100,000) and 691,000 cases of NCGC (ASR 8.8) worldwide. The highest regional rates of both gastric cancer subsites were in Eastern/Southeastern Asia (in men, ASRs: 8.7 and 21.7 for CGC and NCGC, respectively). In most countries NCGC occurred more frequently than CGC with an average ratio of 2:1; however, in some populations where NCGC incidence rates were lower than the global average, CGC rates were similar or higher than NCGC rates. Men had higher rates than women for both subsites but particularly for CGC (male-to-female ratio 3:1).

CONCLUSIONS

This study has, for the first time, quantified global incidence patterns of CGC and NCGC providing new insights into the global burden of these cancers. Country-specific estimates are provided; however, these should be interpreted with caution. This work will support future investigations across populations.

Numerical solution of the relativistic single-site scattering problem for the Coulomb and the Mathieu potential

For a reliable fully-relativistic Korringa-Kohn-Rostoker Green function method, an accurate solution of the underlying single-site scattering problem is necessary. We present an extensive discussion on numerical solutions of the related differential equations by means of standard methods for a direct solution and by means of integral equations. Our implementation is tested and exemplarily demonstrated for a spherically symmetric treatment of a Coulomb potential and for a Mathieu potential to cover the full-potential implementation. For the Coulomb potential we include an analytic discussion of the asymptotic behaviour of irregular scattering solutions close to the origin (r << 1).

Surgical manifestations of gastrointestinal cytomegalovirus infection in children: Clinical audit and literature review

INTRODUCTION

Gastrointestinal sequelae of cytomegalovirus are rare, usually associated with significant immune compromise, and carry a high morbidity and mortality. Gastrointestinal disease frequently requires surgical intervention for diagnosis and management.

AIM

The aim of the study is to evaluate the incidence, presentation and management of gastrointestinal cytomegalovirus disease in a pediatric population.

METHOD

Between January 2003 and June 2011, a retrospective folder review was conducted of all symptomatic children with proven CMV disease, presenting to the surgical service. Eligible patients were identified using the surgical, histopathology and serology databases.

RESULTS

Thirty-eight patients (1.8/1000 surgical admissions) were identified with a median presenting age of 5months (range 3days-12years). Esophagitis (n=18) and small bowel disease (n=16) predominated, but CMV was seen throughout the gastrointestinal tract. Risk factors included HIV infection (n=21, 55%) and recent gastrointestinal surgery or infection (n=10, 26%). Characteristic multiple jejunoileal perforations were seen in six patients. Compared to upper GIT disease, intestinal involvement was associated with younger age and doubled mortality. In HIV-infected children, median CD4 (%) was lower in intestinal compared to upper gastrointestinal disease. Morbidities included anastomotic breakdowns (5), anastomotic strictures (3), relook laparotomies (10), resistant esophageal strictures (5) and prolonged parenteral nutrition (5). Anti-CMV drugs were given in 63%. Overall mortality was 32% (12/38) and was associated with lower GIT disease.

CONCLUSION

Invasive CMV gastrointestinal disease in our children was predominantly HIV-associated, or followed a major lower gastrointestinal inflammatory insult in infants younger than 6months. Successful therapy requires a high index of suspicion of active CMV disease to allow early implementation of CMV viral load control and aggressive treatment of the underlying immune impairment. Multiple surgical interventions are often required for both tissue diagnosis and management of acute and chronic complications. CMV-viral-load-tailored anti-CMV therapy is supported by recent literature.

Comparison of real-time classification systems for arrhythmia detection on Android-based mobile devices

The electrocardiogram (ECG) is a key diagnostic tool in heart disease and may serve to detect ischemia, arrhythmias, and other conditions. Automatic, low cost monitoring of the ECG signal could be used to provide instantaneous analysis in case of symptoms and may trigger the presentation to the emergency department. Currently, since mobile devices (smartphones, tablets) are an integral part of daily life, they could form an ideal basis for automatic and low cost monitoring solution of the ECG signal. In this work, we aim for a realtime classification system for arrhythmia detection that is able to run on Android-based mobile devices. Our analysis is based on 70% of the MIT-BIH Arrhythmia and on 70% of the MIT-BIH Supraventricular Arrhythmia databases. The remaining 30% are reserved for the final evaluation. We detected the R-peaks with a QRS detection algorithm and based on the detected R-peaks, we calculated 16 features (statistical, heartbeat, and template-based). With these features and four different feature subsets we trained 8 classifiers using the Embedded Classification Software Toolbox (ECST) and compared the computational costs for each classification decision and the memory demand for each classifier. We conclude that the C4.5 classifier is best for our two-class classification problem (distinction of normal and abnormal heartbeats) with an accuracy of 91.6%. This classifier still needs a detailed feature selection evaluation. Our next steps are implementing the C4.5 classifier for Android-based mobile devices and evaluating the final system using the remaining 30% of the two used databases.