Right ventricular-vascular coupling ratio in pediatric pulmonary arterial hypertension: A comparison between cardiac magnetic resonance and right heart catheterization measurements.

BACKGROUND: In pulmonary arterial hypertension (PAH), right ventricular (RV) failure is the main cause of mortality. Non-invasive estimation of ventricular-vascular coupling ratio (VVCR), describing contractile response to afterload, could be a valuable tool for monitoring clinical course in children with PAH. This study aimed to test two hypotheses: VVCR by cardiac magnetic resonance (VVCRCMR) correlates with conventional VVCR by right heart catheterization (VVCRRHC) and both correlate with disease severity. METHODS AND RESULTS: Twenty-seven patients diagnosed with idiopathic and associated PAH without post-tricuspid shunt, who underwent RHC and CMR within 17 days at two specialized centers for pediatric PAH were retrospectively studied. Clinical functional status and hemodynamic data were collected. Median age at time of MRI was 14.3 years (IQR: 11.1-16.8), median PVRi 7.6 WU × m2 (IQR: 4.1-12.2), median mPAP 40 mm Hg (IQR: 28-55) and median WHO-FC 2 (IQR: 2-3). VVCRCMR, defined as stroke volume/end-systolic volume ratio was compared to VVCRRHC by single-beat pressure method using correlation and Bland-Altman plots. VVCRCMR and VVCRRHC showed a strong correlation (r = 0.83, p < 0.001). VVCRCMR and VVCRRHC both correlated with clinical measures of disease severity (pulmonary vascular resistance index [PVRi], mean pulmonary artery pressure [mPAP], mean right atrial pressure [mRAP], and World Health Organization functional class [WHO-FC]; all p ≤ 0.02). CONCLUSIONS: Non-invasively measured VVCRCMR is feasible in pediatric PAH and comparable to invasively assessed VVCRRHC. Both correlate with functional and hemodynamic measures of disease severity. The role of VVCR assessed by CMR and RHC in clinical decision-making and follow-up in pediatric PAH warrants further clinical investigation.

Microbial diversity and activity in seafloor brine lake sediments (Alaminos Canyon block 601, Gulf of Mexico).

The microbial communities thriving in deep-sea brines are sustained largely by energy rich substrates supplied through active seepage. Geochemical, microbial activity, and microbial community composition data from different habitats at a Gulf of Mexico brine lake in Alaminos Canyon revealed habitat-linked variability in geochemistry that in turn drove patterns in microbial community composition and activity. The bottom of the brine lake was the most geochemically extreme (highest salinity and nutrient concentrations) habitat and its microbial community exhibited the highest diversity and richness indices. The habitat at the upper halocline of the lake hosted the highest rates of sulfate reduction and methane oxidation, and the largest inventories of dissolved inorganic carbon, particulate organic carbon, and hydrogen sulfide. Statistical analyses indicated a significant positive correlation between the bacterial and archaeal diversity in the bottom brine sample and NH4+ inventories. Other environmental factors with positive correlation with microbial diversity indices were DOC, H2 S, and DIC concentrations. The geochemical regime of different sites within this deep seafloor extreme environment exerts a clear selective force on microbial communities and on patterns of microbial activity.

Effects of discharge on silver loading and transport in the Quinnipiac River, Connecticut.

Silver concentrations were measured in water and sediment samples collected from the Quinnipiac River in Connecticut. This river was chosen for study because of its history of industrialization and high levels of Ag contamination. Sewage treatment plant (STP) effluent accounts for approximately 15% of the total river discharge and approximately 60% of the dissolved Ag in the water column during baseflow conditions. Erosion of contaminated riverbank sediment is the primary source of particulate Ag in the river. Both dissolved and particulate Ag fractions vary as a function of river discharge. Increased discharge due to rain events decreases the relative importance of STP effluent, and thus dilutes the dissolved Ag concentration in the water column. Conversely, increasing discharge results in higher particulate Ag concentrations from increased erosion. The results of this study clearly indicate that both point and non-point sources contribute significantly to Ag loading in this river system, with the level of river discharge determining the relative importance of each.

Is routine roentgenography needed after closed tube thoracostomy removal?

BACKGROUND: Efficacy of chest radiograph protocol after tube thoracostomy tube (CT) removal. METHODS: Retrospective review (July of 1995 to July of 1996) of 141 patients with CT followed throughout their hospitalization. Excluded patients died (23 patients) or had thoracotomy (13 patients) before CT removal. RESULTS: A total of 105 patients had 113 CT removed (mean age, 36.9 years; Injury Severity Score = 23.4; CT duration, 5.0 days). Protocol chest radiographs were performed on average at 7.9 and 22.1 hours. Recurrent pneumothorax (RHPTX = new interpleural air) occurring in 12 patients (11%) and persistent pneumothorax (PHPTX = same volume of interpleural air) occurring in 13 patients (12%) caused no clinical problems and were treated without tube replacement. Three patients had symptoms after removal; none had RHPTX. Two patients had clinical signs; one reaccumulated a hemothorax requiring CT replacement, the other improved without replacement. CONCLUSIONS: Clinically significant RHPTX/PHPTX after CT removal is infrequent. Signs not symptoms detect CT removal complications. At our institution, chest radiographs are obtained in a delayed manner from protocol and offer no benefit over clinical assessment.