Evaluation of Artificial Intelligence-Powered Identification of Large-Vessel Occlusions in a Comprehensive Stroke Center.

BACKGROUND AND PURPOSE: Artificial intelligence algorithms have the potential to become an important diagnostic tool to optimize stroke workflow. Viz LVO is a medical product leveraging a convolutional neural network designed to detect large-vessel occlusions on CTA scans and notify the treatment team within minutes via a dedicated mobile application. We aimed to evaluate the detection accuracy of the Viz LVO in real clinical practice at a comprehensive stroke center. MATERIALS AND METHODS: Viz LVO was installed for this study in a comprehensive stroke center. All consecutive head and neck CTAs performed from January 2018 to March 2019 were scanned by the algorithm for detection of large-vessel occlusions. The system results were compared with the formal reports of senior neuroradiologists used as ground truth for the presence of a large-vessel occlusion. RESULTS: A total of 1167 CTAs were included in the study. Of these, 404 were stroke protocols. Seventy-five (6.4%) patients had a large-vessel occlusion as ground truth; 61 were detected by the system. Sensitivity was 0.81, negative predictive value was 0.99, and accuracy was 0.94. In the stroke protocol subgroup, 72 (17.8%) of 404 patients had a large-vessel occlusion, with 59 identified by the system, showing a sensitivity of 0.82, negative predictive value of 0.96, and accuracy of 0.89. CONCLUSIONS: Our experience evaluating Viz LVO shows that the system has the potential for early identification of patients with stroke with large-vessel occlusions, hopefully improving future management and stroke care.

Evaluation of a new disinfection procedure for ultrasound probes using ultraviolet light.

Following 183 ultrasound examinations, a randomized trial was conducted to compare three procedures for disinfection of probes under routine conditions: dry wiping with a soft, dry, non-sterile paper towel, antiseptic wiping with a towel impregnated with disinfectant spray and dry wiping followed by a 10 min ultraviolet C (UVC) cycle in a disinfection chamber. After ultrasonography, swabs were taken from transducer heads before and after cleaning and streaked onto plates that were then cultured. The number of colonies per plate was counted and organisms identified. The median microbial reduction was 100% for UVC, 98.4% for antiseptic wiping and 87.5% for dry wiping (P<0.001). The percentage of negative specimens was 88% for UVC, 16% for antiseptic wiping and 4% for dry wiping (P<0.0001). Microbial flora was isolated from 12 probes (6.6%) before cleaning, whereas specimens obtained after cleaning contained no pathogens except in one case after antiseptic wiping. UVC disinfection of ultrasound probe may provide a useful method for reducing the bacterial load under routine conditions.

[Echocardiography in athletes]. / L'echocardiographie du sportif.

Echocardiography of athletes focuses on the left ventricle: in many cases, the interpretation is difficult, showing features of either dilated of hypertrophic cardiomyopathy. Accurate analysis requires careful recording of the left ventricle in the fundamental mode. Diagnostic errors by excess are common: overestimation of the chamber size (inadequate incidence), overestimation of wall thickness (failure to recognise right ventricular bands or false tendons). The body size of the individual must be considered when interpreting the chamber dimensions. The diastolic left ventricular dimension is often < 60 mm but it may attain 70 mm. In these cases, left ventricular function must be accurately determined and shown to be normal, which may prove difficult as the resting left ventricular ejection fraction is physiologically lower in trained athletes. The use of stress echo (exercise left ventricular ejection fraction) and Doppler tissue imaging (left ventricular filling) are often indispensable. Left ventricular wall thickness is rarely > 13 mm. a situation where the possibility of hypertrophic cardiomyopathy has to be assessed. Left atrial dilatation is inconstant and aortic root dilatation is very unusual. The right heart chambers are usually globally dilated and the inferior vena cava may seem abnormally dilated.

[The best of echocardiography in 2005]. / L'essentiel de 2005 en échocardiographie.

Echocardiography continues to evolve in several directions: on the technical front, various tools are being developed and real time 3D is starting to find a place in routine practice as much as contrast is used unequally depending on the country. On the diagnostic front, certain aspects have been particularly emphasised this year: The key role of quantification of valvulopathies in order to guide management, both at rest and on effort. The place of echocardiography in asynchronism, even if a more consensual strategy is needed to take into account the different approaches. The very good prognostic series on stress echography in the context of myocardial ischaemia. Advances in the evaluation of filling pressures have allowed a better definition of the limits, and have refined the understanding of so-called 'diastolic' cardiac failure. Finally, the role of echography to guide and also evaluate the results of foramen ovale or interatrial communication closure.

[Echocardiographic indices of diastolic function put to the practical test]. / Indices echocardiographiques de fonction diastolique a l'epreuve de la pratique.

Assessment of left ventricular filling pressures is now part of routine echocardiographic examination. It is a semi-quantitative evaluation usually based on analysis of transmitral blood flow. Restrictive type flow associated with poor left ventricular contraction is pathognomonic of increased left ventricular filling pressure: conversely, inversion of the mitral flow velocities is generally reassuring except in the presence of left ventricular hypertrophy. In other cases, it is necessary to complete the analysis with indices of left ventricular relaxation. The authors discuss the advantages of pulsed Doppler tissue imaging at the mitral ring over the propagation velocity in colour M-mode, especially when left ventricular contraction is normal or relatively preserved. In particular, the reproducibility of propagation velocity measurements is poor when the velocities are relatively high (> 50 cm/s) because a small error in measurement at these velocities has large repercussion on the value of the slope. Pulmonary vein flow, reputedly difficult to analyse, may be very valuable. Discordance of the different indices is one of the most difficult daily problems to resolve. However, it is possible to give a reliable "normal filling pressures" or "increased filling pressures" conclusion in over 80% of cases. Echocardiography cannot provide a precise study of diastole and terms such as abnormal relaxation, abnormal compliance or diastolic dysfunction should be avoided.

[The best of echocardiography in 2004]. / L'essentiel de 2004 en échocardiographie.

What major trends can we single out from the large amount of literature that appeared in 2004? The role of echography in the investigation of asynchronism has most certainly been better defined. Real time 3D echography, now routinely available, has started to gain respect in different pathologies. The place of filling pressure evaluation in patients' management, as much diagnostic as therapeutic, has again been refined. The prognostic contribution of stress echography has been emphasized in particular this year. Despite a still limited routine role, publications regarding contrast techniques have been quite numerous: not only diagnostic contrast echography, but also contrast and pleiotropic gene transfer in the myocardium. The study of coronary reserve via the transthoracic route, possibly assisted with contrast, should become established as a routine technique.

[Echographic calculation of left ventricular mass in TM mode]. / Calcul échocardiographique de la masse ventriculaire gauche en mode TM. Evaluation de nouvelles techniques d'imagerie.

UNLABELLED: TM sections of the left ventricle (LV) have only been validated in fundamental (F) imaging. We were interested in evaluating the repercussions of new imaging techniques, harmonic (H) and colour tissue Doppler (CTD), on the TM measurement of left ventricular mass (LVM), the reference imaging being F imaging. METHOD: We performed a prospective study, including 26 patients with a valid TM section. The LV and LVM parameters in F, H and CTD mode according to the Penn and ASE conventions as well as the inter-observer reproducibility were studied. RESULTS: The correlations for the LVM measurements between F and H, and between F and CTD were high whichever convention was used (r>0.95, p<0.0001). For each observer, the LVM in H and in CTD was always greater than the LVM in F with both conventions (p<0.02). A false diagnosis of LV hypertrophy was made in 27% of patients in H and in 15% of patients in CTD. The best inter-observer reproducibility was obtained in H: the average inter-observer difference (gr.) was 23+/-15 for H, 32+/-19 for F and 59+/-18 for CTD. CONCLUSION: H and CTD imaging entail an overestimation of LVM, essentially by overestimation of the parietal thickness of the LV. The inter-observer reproducibility was excellent in H and poor in CTD. The use of the harmonic mode for LVM calculation must be validated using new formulae.

[Quantification of valvular regurgitation by the convergence zone method]. / Quantification des régurgitations valvulaires par la méthode de la zone de convergence.

The convergence zone method is currently used routinely to quantify valvular regurgitation, particularly mitral insufficiency, but also aortic and tricuspid regurgitation. It is quick to perform, requires relatively little training and remains valid in the presence of atrial fibrillation and in the association of regurgitation-stenosis. It relies on the measurement of output at the level of an isovelocity hemisphere and allows calculation of the regurgitant orifice surface (SOR) and the regurgitant volume per beat (VR). It is reserved for severe regurgitation corresponding to angiographic grade 4: SOR > 40 mm2 and VR > 60 ml for mitral insufficiency, SOR > 30 mm2 and VR > 60 ml for aortic insufficiency, and SOR > 40 mm2 and VR > 40 ml for tricuspid insufficiency.

[Hemodynamic assessment and prognostic data obtained by echography in cardiac insufficiency]. / Bilan hémodynamique et données pronostiques obtenues par échographie chez l'insuffisant cardiaque.

The evaluation and follow up of insufficiency are matters of "routine" echography. The relevant parameters allow an evaluation of the contractility of the left ventricle (LV), cardiac output, filling pressures, significance of mitral insufficiency (MI), pulmonary pressures, and volumes, and one of the aims is to be able to offer an exhaustive haemodynamic assessment without unnecessarily prolonging the length of the examination. Calculation of the LV ejection fraction is an unavoidable parameter (it is often the inclusion criterion in large studies), recently "rehabilitated" thanks to harmonic imaging. However, the dependence on this index with respect to load conditions, is in fact a very imperfect reflection of LV contractility. The calculation of systolic ejection volume with Doppler (for example from the outflow chamber diameter and sub aortic flow) is a better reflection of LV performance. In the same manner, analysis of the ascending slope of MI flow during isovolumetric contraction (dp/dt) recorded with continuous Doppler allows a reasonably reliable and simple approach to LV contractility, only slightly dependent on load conditions. Numerous parameters allow a reliable evaluation of LV filling pressures: this always relies on the transmitral flow morphology, which has been better interpreted for several years, possibly coupled with a recording of pulmonary venous flow, or even a colour TM mode recording of LV filling or a pulsed tissular Doppler flow recording at the mitral ring. Analysis of the right side of the heart consists of evaluation of the size of the cavities and quantification of the tricuspid flow. Even if the flow is not laminar, it allows a reliable measurement of the pulmonary pressures (by default, pulmonary flow is determined). TM recording in the inferior vena cava has to be systematic to allow evaluation of the right-sided pressures and volumes. Interpretation of these various parameters allows a subtle haemodynamic evaluation in severe cardiac insufficiency, for which the significance is not only diagnostic, but also prognostic: adverse effect of low LVEF; adverse effect of restrictive mitral flow (E/A ratio > 2 and in particular short E deceleration time less than 150 ms), especially if it is not modified by treatment.

[Quantification of mitral regurgitation]. / Quantification des insuffisances mitrales.

The echographic methods of quantification of mitral regurgitation are various. Semiquantitative methods using the color Doppler extension of the regurgitant jet are now replaced by more quantitative methods, including PISA, jet width, and regurgitant fraction. Although sometimes difficult, accurate quantification of mitral regurgitation is now possible in a majority of patients using transthoracic echocardiography.

[Value of factor analysis in a wall motion study: preliminary application in the detection of left ventricular segmental contraction ischemic disorders by echocardiography]. / Apport d'une analyse factorielle à l'étude de mouvements: application préliminaire à la détection par échocardiographie des troubles de la contraction segmentaire du ventricule gauche ischémique.

PURPOSE: Factor Analysis of Medical Image Sequences (FAMIS) was tested to study the regional wall motion of the left ventricle at echocardiography. MATERIALS AND METHODS: FAMIS analyzed the time signal curves of each pixel. One flat curve and one curve describing the contraction-relaxation of the left ventricle were first estimated. The contributions of the curve of each pixel to the two previous curves were computed, yielding two "factor images". The spatial distribution of positive and negative coefficients of the second factor image was analyzed. The evaluation was carried out on 222 segments (20 patients, 18 parasternal short-axis views, 17 apical four-chamber views, and 15 apical two-chamber views). A first echocardiographer reviewed the factor images and the reading was compared to the conventional reading of the cine-loops by two other echocardiographers. Each segment was scored as normal, hypokinetic, akinetic, or dyskinetic. RESULTS: On normal segments, the positive coefficients of the second factor image were on the inner side, the negative coefficients were on the outer side. Dyskinesis yields the opposite pattern. Hypokinesis and akinesis give intermediate images. An absolute concordance was obtained on 71.2% of all segments between the two types of reading. Larger discrepancies were found for akinetic and hypokinetic segments. CONCLUSION: FAMIS is a promising tool to study regional wall motion of the left ventricle.

Determinants of right ventricular pressure in mild hypertension.

OBJECTIVE: Doppler echocardiography was used to define reference values and determinants of tricuspid regurgitation peak velocity (TRV) in hypertensive patients. A TRV value > 2.5 m/s is the threshold usually defining abnormal right ventricular systolic pressure. DESIGN AND PATIENTS: Doppler echocardiography was performed in 320 consecutive uncomplicated hypertensive patients, without overt pulmonary or heart disease. Doppler echocardiography included LV mass measurement, LV inflow and pulmonary venous flow analysis, LV systolic function and TRV measurements. RESULTS: Among 320 patients, 255 had normal TRV < 2.5 m/s and 65 had elevated TRV > or = 2.5 m/s. Compared with the normal TRV group, the elevated TRV group was older (60 versus 50 years, P < 0.0001), systolic blood pressure was higher (156 versus 151 mmHg, P = 0.02) and antihypertensive therapy was more frequent (68 versus 51%, P = 0.02); indexed LV mass was higher (45.4 versus 40.6 g/m2.7, P = 0.001), pulmonary D wave peak velocity was higher (42 versus 38 cm/s, P = 0.03). In univariate analysis, age was the most predictive variable of TRV (r = 0.36). In multivariate analysis, three variables were independently related to TRV: age, LV mass, pulmonary D wave (multiple r = 0.47). CONCLUSION: In mild hypertension, TRV is independently related to age, and to a lesser extent, to LV morphology and LV filling pressure. In clinical practice, age should be taken into account to interpret TRV.

Genetic and environmental influences on left ventricular mass. A family study.

The relations between left ventricular mass (LVM) with age, gender, body size, and blood pressure were investigated in healthy adults and children from 149 nuclear families. LVM was strongly correlated with overall weight, especially in the children. Genetic analysis indicated that the segregation of LVM was compatible with an additive polygenic model, with a heritability estimate of 34% before adjustment for weight and 28% after adjustment for weight. Genetic and/or familial environmental factors played a strong role in the correlation of LVM and weight; they accounted for all of the correlation between the 2 traits in adults and 59% of the correlation in children. Spouses exhibited a strong correlation in their weight, which suggested that common family environment may contribute to the family correlations and to the observed heritability of the trait. LVM was strongly correlated with blood pressure before adjustment for weight, but this correlation could be attributed to nonfamilial environment rather than genetic factors. After adjustment for weight, the intertrait correlations between LVM and blood pressure were nonsignificant. Thus, adjustment for weight accounts for all common determinants of LVM and blood pressure.

Mapping of a first locus for autosomal dominant myxomatous mitral-valve prolapse to chromosome 16p11.2-p12.1.

Myxomatous mitral-valve prolapse (MMVP), also called Barlow disease, is a common cardiac abnormality and affects up to 5% of the population. It is characterized by an excess of tissue that leads to billowing of the mitral leaflets, sometimes complicated by prolapse. Typical histological findings include myxomatous degeneration and degradation of collagen and elastin. Previous reports have proposed an autosomal dominant inheritance of the trait, with age- and sex-dependent expression. By systematic echocardiographic screening of the first-degree relatives of 17 patients who underwent mitral-valve repair, we have identified four pedigrees showing such an inheritance. Genomewide linkage analysis of the most informative pedigree (24 individuals, three generations) showed a significant linkage for markers mapping to chromosome 16p, with a two-point maximum LOD score for D16S3068 (Zmax=3.30 at straight theta=0). Linkage to D16S3068 was confirmed in a second family (Zmax=2.02 at straight theta=0) but was excluded for the two remaining families, thus demonstrating the genetic heterogeneity of the disease. Multipoint linkage analysis performed, with nine additional markers, on the two families with linkage gave maximum multipoint LOD scores of 5.45 and 5.68 for D16S3133, according to a conservative and a stringent model, respectively. Haplotype analysis defined a 5-cM minimal MMVP-1 locus between D16S3068 (16p11.2) and D16S420 (16p12. 1) and a 34-cM maximal interval between D16S404 and D16S3068 when recombination events were taken into account only in affected individuals. The identification of this locus represents a first step toward a new molecular classification of mitral-valve prolapse.

Can echocardiography identify mildly hypertensive patients at high risk, left untreated based on current guidelines?

OBJECTIVE: To determine whether the decision to treat uncomplicated mild hypertension with drugs, in accordance with the World Health Organization - International Society of Hypertension (WHO/ISH) guidelines based on a series of blood pressure (BP) measurements over 6 months, resulted in the treatment of patients at high risk on the basis of echocardiography. METHODS: One hundred and eighteen patients with mild hypertension (diastolic blood pressure 90-105 mm Hg and/or systolic blood pressure 140-180 mm Hg) were examined by echocardiography at inclusion and followed up for 6 months by a single physician unaware of the echographic results. RESULTS: Drug treatment was given to 48 patients, and 70 remained untreated. Treated patients had higher echographic indices than untreated patients (all P<0.05): left ventricular (LV) mass/body surface area (83.0+/-15.6 versus 75.3+/-14.8 g/m2), inter-ventricular septal thickness (9.7+/-1.7 versus 8.5+/-1.3 mm), LV posterior wall thickness (8.4+/-1.1 versus 7.8+/-1.1 mm), relative wall thickness (0.37+/-0.06 versus 0.34+/-0.06). LV geometry was normal in 98 patients, and 20 had LV concentric remodelling. The 10-year coronary disease risk (Framingham equation) was higher in the 20 patients with concentric remodelling than in those with normal LV geometry (10.4 versus 4.2%; P<0.005). Nine of these 20 patients were still untreated at the end of the 6-month follow-up period. CONCLUSION: Rigorous application of the WHO/ISH clinical guidelines in a group of mild hypertensive patients led to the treatment of patients with slightly higher LV mass and more concentric LV geometry than were found in those not treated. However, a high-risk subgroup, with concentric remodelling, was not identified and left untreated.