Cardiovascular magnetic resonance evaluation of aortic stenosis severity using single plane measurement of effective orifice area

<p>Abstract</p> <p>Background</p> <p>Transthoracic echocardiography (TTE) is the standard method for the evaluation of the severity of aortic stenosis (AS). Valve effective orifice area (EOA) measured by the continuity equation is one of the most frequently used stenotic indices. However, TTE measurement of aortic valve EOA is not feasible or not reliable in a significant proportion of patients. Cardiovascular magnetic resonance (CMR) has emerged as a non-invasive alternative to evaluate EOA using velocity measurements. The objectives of this study were: 1) to validate a new CMR method using jet shear layer detection (JSLD) based on acoustical source term (AST) concept to estimate the valve EOA; 2) to introduce a simplified JSLD method not requiring vorticity field derivation.</p> <p>Methods and results</p> <p>We performed an in vitro study where EOA was measured by CMR in 4 fixed stenoses (EOA = 0.48, 1.00, 1.38 and 2.11 cm²) under the same steady flow conditions (4-20 L/min). The in vivo study included eight (8) healthy subjects and 37 patients with mild to severe AS (0.72 cm²≤ EOA ≤ 1.71 cm²). All subjects underwent TTE and CMR examinations. EOA was determinated by TTE with the use of continuity equation method (TTE_CONT). For CMR estimation of EOA, we used 3 methods: 1) Continuity equation (CMR_CONT); 2) Shear layer detection (CMR_JSLD), which was computed from the velocity field of a single CMR velocity profile at the peak systolic phase; 3) Single plane velocity truncation (CMR_SPVT), which is a simplified version of CMR_JSLDmethod. There was a good agreement between the EOAs obtained in vitro by the different CMR methods and the EOA predicted from the potential flow theory. In the in vivo study, there was good correlation and concordance between the EOA measured by the TTE_CONTmethod versus those measured by each of the CMR methods: CMR_CONT(r = 0.88), CMR_JSLD(r = 0.93) and CMR_SPVT(r = 0.93). The intra- and inter- observer variability of EOA measurements was 5 ± 5% and 9 ± 5% for TTE_CONT, 2 ± 1% and 7 ± 5% for CMR_CONT, 7 ± 5% and 8 ± 7% for CMR_JSLD, 1 ± 2% and 3 ± 2% for CMR_SPVT. When repeating image acquisition, reproducibility of measurements was 10 ± 8% and 12 ± 5% for TTE_CONT, 9 ± 9% and 8 ± 8% for CMR_CONT, 6 ± 5% and 7 ± 4% for CMR_JSLDand 3 ± 2% and 2 ± 2% for CMR_SPVT.</p> <p>Conclusion</p> <p>There was an excellent agreement between the EOA estimated by the CMR_JSLDor CMR_SPVTmethods and: 1) the theoretical EOA in vitro, and 2) the TTE_CONTEOA in vivo. The CMR_SPVTmethod was superior to the TTE and other CMR methods in terms of measurement variability. The novel CMR-based methods proposed in this study may be helpful to corroborate stenosis severity in patients for whom Doppler-echocardiography exam is inconclusive.</p

Molecular diversity of Mycobacterium tuberculosis isolates from patients with pulmonary tuberculosis in Mozambique

<p>Abstract</p> <p>Background</p> <p>Mozambique is one of the countries with the highest burden of tuberculosis (TB) in Sub-Saharan Africa, and information on the predominant genotypes of <it>Mycobacterium tuberculosis </it>circulating in the country are important to better understand the epidemic. This study determined the predominant strain lineages that cause TB in Mozambique.</p> <p>Results</p> <p>A total of 445 <it>M. tuberculosis </it>isolates from seven different provinces of Mozambique were characterized by spoligotyping and resulting profiles were compared with the international spoligotyping database SITVIT2.</p> <p>The four most predominant lineages observed were: the Latin-American Mediterranean (LAM, n = 165 or 37%); the East African-Indian (EAI, n = 132 or 29.7%); an evolutionary recent but yet ill-defined T clade, (n = 52 or 11.6%); and the globally-emerging Beijing clone, (n = 31 or 7%). A high spoligotype diversity was found for the EAI, LAM and T lineages.</p> <p>Conclusions</p> <p>The TB epidemic in Mozambique is caused by a wide diversity of spoligotypes with predominance of LAM, EAI, T and Beijing lineages.</p

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p&lt;0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p&lt;0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised