Background To determine if hot, humid ambient conditions impact filtering facepiece respirators' (FFRs') fit, and to evaluate differences in physiologic and subjective responses between N95 FFRs and ...P100 FFRs. Methods Twelve subjects had physiologic monitoring and subjective perceptions monitored over 1 hour of treadmill exercise (5.6 km/h) in an environmental chamber (35°C, relative humidity 50%) wearing an N95 FFR, P100 FFR, or no respirator. Respirator quantitative fit testing was done before and after exercise. Results There was no significant difference in pass rates for both FFRs on initial fit testing, but subjects who passed were more likely to fail the postexercise test with N95 FFRs ( P = .01). Wearing FFRs increased the temperature of facial skin covered by the FFR ( P = .009) and breathing discomfort ( P = .002). No significant differences were noted in other measured variables (heart rate, respiratory rate, oxygen saturation, transcutaneous carbon dioxide level, rectal temperature, global skin temperature, core temperature, and subjective perceptions) between controls and FFRs and between FFR models. Conclusion After 1 hour of exercise in hot, humid ambient conditions, P100 FFRs retained better fit than N95 FFRs, without additional physiologic or subjective impact. Wearing FFRs under these conditions does not add to the body's thermophysiologic or perceptual burdens.
In patients with known or suspected myocardial infarction (MI), cardiovascular magnetic resonance (CMR) provides a comprehensive, multifaceted view of the heart. The data, including that from a ...recent multicenter clinical trial, indicate that delayed-enhancement cardiac magnetic resonance imaging (DE-CMR) is a well-validated, robust technique that can be easily implemented on scanners that are commonly available worldwide, with an effectiveness that clearly rivals the best available imaging techniques for the detection and assessment of acute and chronic MI. When patients present outside the diagnostic window of cardiac troponins, DE-CMR may be especially useful. Moreover, because DE-CMR can uniquely differentiate between ischemic and various nonischemic forms of myocardial injury, it may be helpful in cases of diagnostic uncertainty, such as in patients with classical features of MI in whom coronary angiography does not show a culprit lesion. Even after the diagnosis of MI has been made, CMR provides clinically relevant information by identifying residual viability, microvascular damage, stunning, and right ventricular infarction. In addition, post-MI sequelae, including left ventricular thrombus and pericarditis, are easily identified. Given that quantification of infarct size by DE-CMR is highly reproducible, this technique may provide a useful surrogate end point for clinical trials with appreciable reductions in sample size compared with alternative methods.
Routine cine cardiovascular magnetic resonance (CMR) allows for the measurement of left atrial (LA) volumes. Normal reference values for LA volumes have been published based on a group of European ...individuals without known cardiovascular disease (CVD) but not on one of similar United States (US) based volunteers. Furthermore, the association between grades of LA dilatation by CMR and outcomes has not been established. We aimed to assess the relationship between grades of LA dilatation measured on CMR based on US volunteers without known CVD and all-cause mortality in a large, multicenter cohort of patients referred for a clinically indicated CMR scan.
We identified 85 healthy US subjects to determine normal reference LA volumes using the biplane area-length method and indexed for body surface area (LAVi). Clinical CMR reports of patients with LA volume measures (n = 11,613) were obtained. Data analysis was performed on a cloud-based system for consecutive CMR exams performed at three geographically distinct US medical centers from August 2008 through August 2017. We identified 10,890 eligible cases. We categorized patients into 4 groups based on LAVi partitions derived from US normal reference values: Normal (21-52 ml/m
), Mild (52-62 ml/m
), Moderate (63-73 ml/m
) and Severe (> 73 ml/m
). Mortality data were ascertained for the patient group using electronic health records and social security death index. Cox proportional hazard risk models were used to derive hazard ratios for measuring association of LA enlargement and all-cause mortality.
The distribution of LAVi from healthy subjects without known CVD was 36.3 ± 7.8 mL/m
. In clinical patients, enlarged LA was associated with older age, atrial fibrillation, hypertension, heart failure, inpatient status and biventricular dilatation. The median follow-up duration was 48.9 (IQR 32.1-71.2) months. On univariate analyses, mild Hazard Ratio (HR) 1.35 (95% Confidence Interval CI 1.11 to 1.65, moderate HR 1.51 (95% CI 1.22 to 1.88) and severe LA enlargement HR 2.14 (95% CI 1.81 to 2.53) were significant predictors of death. After adjustment for significant covariates, moderate HR 1.45 (95% CI 1.1 to 1.89) and severe LA enlargement HR 1.64 (95% CI 1.29 to 2.08) remained independent predictors of death.
LAVi determined on routine cine-CMR is independently associated with all-cause mortality in patients undergoing a clinically indicated CMR.
Highlights ► Mean core temperature is not significantly increased (<0.1 °C) by the use of a surgical mask at a low-moderated work rate over 1 h. ► Respiratory rate is minimally increased (1.6 ...breaths-per-minute) with use of a surgical mask over 1 h at a low-moderate work rate. ► Heart rate is increased by 8% with the use of a surgical mask over 1 h at a low-moderate work rate.
Objectives This study tested the diagnostic and prognostic utility of a rapid, visual T1 assessment method for identification of cardiac amyloidosis (CA) in a “real-life” referral population ...undergoing cardiac magnetic resonance for suspected CA. Background In patients with confirmed CA, delayed-enhancement cardiac magnetic resonance (DE-CMR) frequently shows a diffuse, global hyperenhancement (HE) pattern. However, imaging is often technically challenging, and the prognostic significance of diffuse HE is unclear. Methods Ninety consecutive patients referred for suspected CA and 64 hypertensive patients with left ventricular hypertrophy (LVH) were prospectively enrolled and underwent a modified DE-CMR protocol. After gadolinium administration a method for rapid, visual T1 assessment was used to identify the presence of diffuse HE during the scan, allowing immediate optimization of settings for the conventional DE-CMR that followed. The primary endpoint was all-cause mortality. Results Among patients with suspected CA, 66% (59 of 90) demonstrated HE, with 81% (48 of 59) of these meeting pre-specified visual T1 assessment criteria for diffuse HE. Among hypertensive LVH patients, 6% (4 of 64) had HE, with none having diffuse HE. During 29 months of follow-up (interquartile range: 12 to 44 months), there were 50 (56%) deaths in patients with suspected CA and 4 (6%) in patients with hypertensive LVH. Multivariable analysis demonstrated that the presence of diffuse HE was the most important predictor of death in the group with suspected CA (hazard ratio: 5.5, 95% confidence interval: 2.7 to 11.0; p < 0.0001) and in the population as a whole (hazard ratio: 6.0, 95% confidence interval 3.0 to 12.1; p < 0.0001). Among 25 patients with myocardial histology obtained during follow-up, the sensitivity, specificity, and accuracy of diffuse HE in the diagnosis of CA were 93%, 70%, and 84%, respectively. Conclusions Among patients suspected of CA, the presence of diffuse HE by visual T1 assessment accurately identifies patients with histologically-proven CA and is a strong predictor of mortality.
In these patients, optimization of acquisition parameters can significantly improve image quality. ...new LGE techniques, including dark blood delayed enhancement, have been described and appear to ...have additive clinical utility. ...it is timely to present an update on how we perform LGE at our center 2. ...breatheld segmented IR-GRE and/or FIDDLE images are acquired in the left ventricular (LV) short and long axis views (2-, 3-, and 4- chamber views). ...when attempting to visualize infarction or scar, there is substantial patient to patient variation in the clearance of contrast, and using a fixed wait time before acquiring LGE images can result in missing the optimal imaging window in individuals with rapid contrast clearance.
Nonischemic cardiomyopathy is a leading cause of reduced left ventricular ejection fraction (LVEF) and is associated with high mortality risk from progressive heart failure and arrhythmias. ...Myocardial scar on cardiovascular magnetic resonance imaging is increasingly recognized as a risk marker for adverse outcomes; however, left ventricular dysfunction remains the basis for determining a patient's eligibility for primary prophylaxis with implantable cardioverter-defibrillator. We investigated the relationship of LVEF and scar with long-term mortality and mode of death in a large cohort of patients with nonischemic cardiomyopathy.
This study is a prospective, longitudinal outcomes registry of 1020 consecutive patients with nonischemic cardiomyopathy who underwent clinical cardiovascular magnetic resonance imaging for the assessment of LVEF and scar at 3 centers.
During a median follow-up of 5.2 (interquartile range, 3.8, 6.6) years, 277 (27%) patients died. On survival analysis, LVEF ≤35% and scar were strongly associated with all-cause (log-rank test
=0.002 and
<0.001, respectively) and cardiac death (
=0.001 and
<0.001, respectively). Whereas scar was strongly related to sudden cardiac death (SCD;
=0.001), there was no significant association between LVEF ≤35% and SCD risk (
=0.57). On multivariable analysis including established clinical factors, LVEF and scar are independent risk markers of all-cause and cardiac death. The addition of LVEF provided incremental prognostic value but insignificant discrimination improvement by C-statistic for all-cause and cardiac death, but no incremental prognostic value for SCD. Conversely, scar extent demonstrated significant incremental prognostic value and discrimination improvement for all 3 end points. On net reclassification analysis, the addition of LVEF resulted in no significant improvement for all-cause death (11.0%; 95% CI, -6.2% to 25.9%), cardiac death (9.8%; 95% CI, -5.7% to 29.3%), or SCD (7.5%; 95% CI, -41.2% to 42.9%). Conversely, the addition of scar extent resulted in significant reclassification improvement of 25.5% (95% CI, 11.7% to 41.0%) for all-cause death, 27.0% (95% CI, 11.6% to 45.2%) for cardiac death, and 40.6% (95% CI, 10.5% to 71.8%) for SCD.
Myocardial scar and LVEF are both risk markers for all-cause and cardiac death in patients with nonischemic cardiomyopathy. However, whereas myocardial scar has strong and incremental prognostic value for SCD risk stratification, LVEF has no incremental prognostic value over clinical measures. Scar assessment should be incorporated into patient selection criteria for primary prevention implantable cardioverter-defibrillator placement.
Anaerobic polycyclic hydrocarbon (PAH) degradation coupled to sulfate reduction may be an important mechanism for in situ remediation of contaminated sediments. Steps involved in the anaerobic ...degradation of 2-methylnaphthalene have been described in the sulfate reducing strains NaphS3, NaphS6 and N47. Evidence from N47 suggests that naphthalene degradation involves 2-methylnaphthalene as an intermediate, whereas evidence in NaphS2, NaphS3 and NaphS6 suggests a mechanism for naphthalene degradation that does not involve 2-methylnaphthalene. To further characterize pathways involved in naphthalene degradation in NaphS2, the draft genome was sequenced, and gene and protein expression examined.
Draft genome sequencing, gene expression analysis, and proteomic analysis revealed that NaphS2 degrades naphthoyl-CoA in a manner analogous to benzoyl-CoA degradation. Genes including the previously characterized NmsA, thought to encode an enzyme necessary for 2-methylnaphthalene metabolism, were not upregulated during growth of NaphS2 on naphthalene, nor were the corresponding protein products. NaphS2 may possess a non-classical dearomatizing enzyme for benzoate degradation, similar to one previously characterized in Geobacter metallireducens. Identification of genes involved in toluene degradation in NaphS2 led us to determine that NaphS2 degrades toluene, a previously unreported capacity. The genome sequence also suggests that NaphS2 may degrade other monoaromatic compounds.
This study demonstrates that steps leading to the degradation of 2-naphthoyl-CoA are conserved between NaphS2 and N47, however while NaphS2 possesses the capacity to degrade 2-methylnaphthalene, naphthalene degradation likely does not proceed via 2-methylnaphthalene. Instead, carboxylation or another form of activation may serve as the first step in naphthalene degradation. Degradation of toluene and 2-methylnaphthalene, and the presence of at least one bss-like and bbs-like gene cluster in this organism, suggests that NaphS2 degrades both compounds via parallel mechanisms. Elucidation of the key genes necessary for anaerobic naphthalene degradation may provide the ability to track naphthalene degradation through in situ transcript monitoring.
Abstract
Aims
Cardiovascular magnetic resonance (CMR) imaging is a key diagnostic tool for the evaluation of patients with suspected cardiac tumours. Patient management is guided by the CMR ...diagnosis, including no further testing if a mass is excluded or if only a pseudomass is found. However, there are no outcomes studies validating this approach.
Methods and results
In this multicentre study of patients undergoing clinical CMR for suspected cardiac tumour, CMR diagnoses were assigned as no mass, pseudomass, thrombus, benign tumour, or malignant tumour. A final diagnosis was determined after follow-up using all available data. The primary endpoint was all-cause mortality. Among 903 patients, the CMR diagnosis was no mass in 25%, pseudomass in 16%, thrombus in 16%, benign tumour in 17%, and malignant tumour in 23%. Over a median of 4.9 years, 376 patients died. Compared with the final diagnosis, the CMR diagnosis was accurate in 98.4% of patients. Patients with CMR diagnoses of pseudomass and benign tumour had similar mortality to those with no mass, whereas those with malignant tumour hazard ratio (HR) 3.31 (2.40–4.57) and thrombus HR 1.46 (1.00–2.11) had greater mortality. The CMR diagnosis provided incremental prognostic value over clinical factors including left ventricular ejection fraction, coronary artery disease, and history of extracardiac malignancy (P < 0.001).
Conclusion
In patients with suspected cardiac tumour, CMR has high diagnostic accuracy. Patients with CMR diagnoses of no mass, pseudomass, and benign tumour have similar long-term mortality. The CMR diagnosis is a powerful independent predictor of mortality incremental to clinical risk factors.
Graphical Abstract
In patients with suspected cardiac tumour, CMR has high diagnostic accuracy and is an excellent independent predictor of long-term mortality.
Phase contrast (PC) cardiovascular magnetic resonance (CMR) is widely employed for flow quantification, but analysis typically requires time consuming manual segmentation which can require human ...correction. Advances in machine learning have markedly improved automated processing, but have yet to be applied to PC-CMR. This study tested a novel machine learning model for fully automated analysis of PC-CMR aortic flow.
A machine learning model was designed to track aortic valve borders based on neural network approaches. The model was trained in a derivation cohort encompassing 150 patients who underwent clinical PC-CMR then compared to manual and commercially-available automated segmentation in a prospective validation cohort. Further validation testing was performed in an external cohort acquired from a different site/CMR vendor.
Among 190 coronary artery disease patients prospectively undergoing CMR on commercial scanners (84% 1.5T, 16% 3T), machine learning segmentation was uniformly successful, requiring no human intervention: Segmentation time was < 0.01 min/case (1.2 min for entire dataset); manual segmentation required 3.96 ± 0.36 min/case (12.5 h for entire dataset). Correlations between machine learning and manual segmentation-derived flow approached unity (r = 0.99, p < 0.001). Machine learning yielded smaller absolute differences with manual segmentation than did commercial automation (1.85 ± 1.80 vs. 3.33 ± 3.18 mL, p < 0.01): Nearly all (98%) of cases differed by ≤5 mL between machine learning and manual methods. Among patients without advanced mitral regurgitation, machine learning correlated well (r = 0.63, p < 0.001) and yielded small differences with cine-CMR stroke volume (∆ 1.3 ± 17.7 mL, p = 0.36). Among advanced mitral regurgitation patients, machine learning yielded lower stroke volume than did volumetric cine-CMR (∆ 12.6 ± 20.9 mL, p = 0.005), further supporting validity of this method. Among the external validation cohort (n = 80) acquired using a different CMR vendor, the algorithm yielded equivalently small differences (∆ 1.39 ± 1.77 mL, p = 0.4) and high correlations (r = 0.99, p < 0.001) with manual segmentation, including similar results in 20 patients with bicuspid or stenotic aortic valve pathology (∆ 1.71 ± 2.25 mL, p = 0.25).
Fully automated machine learning PC-CMR segmentation performs robustly for aortic flow quantification - yielding rapid segmentation, small differences with manual segmentation, and identification of differential forward/left ventricular volumetric stroke volume in context of concomitant mitral regurgitation. Findings support use of machine learning for analysis of large scale CMR datasets.
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