Diagnostic and prognostic significance of cardiovascular magnetic resonance native myocardial T1 mapping in patients with pulmonary hypertension

Background

Native T1 may be a sensitive, contrast-free, non-invasive cardiovascular magnetic resonance (CMR) marker of myocardial tissue changes in patients with pulmonary artery hypertension. However, the diagnostic and prognostic value of native T1 mapping in this patient group has not been fully explored. The aim of this work was to determine whether elevation of native T1 in myocardial tissue in pulmonary hypertension: (a) varies according to pulmonary hypertension subtype; (b) has prognostic value and (c) is associated with ventricular function and interaction.

Methods

Data were retrospectively collected from a total of 490 consecutive patients during their clinical 1.5 T CMR assessment at a pulmonary hypertension referral centre in 2015. Three hundred sixty-nine patients had pulmonary hypertension [58?±?15 years; 66% female], an additional 39 had pulmonary hypertension due to left heart disease [68?±?13 years; 60% female], 82 patients did not have pulmonary hypertension [55?±?18; 68% female]. Twenty five healthy subjects were also recruited [58 ±4 years); 51% female]. T1 mapping was performed with a MOdified Look-Locker Inversion Recovery (MOLLI) sequence. T1 prognostic value in patients with pulmonary arterial hypertension was assessed using multivariate Cox proportional hazards regression analysis.

Results

Patients with pulmonary artery hypertension had elevated T1 in the right ventricular (RV) insertion point (pulmonary hypertension patients: T1?=?1060?±?90 ms; No pulmonary hypertension patients: T1?=?1020?±?80 ms p <?0.001; healthy subjects T1?=?940?±?50 ms p <?0.001) with no significant difference between the major pulmonary hypertension subtypes. The RV insertion point was the most successful T1 region for discriminating patients with pulmonary hypertension from healthy subjects (area under the curve?=?0.863) however it could not accurately discriminate between patients with and without pulmonary hypertension (area under the curve?=?0.654). T1 metrics did not contribute to prediction of overall mortality (septal: p =?0.552; RV insertion point: p =?0.688; left ventricular free wall: p =?0.258). Systolic interventricular septal angle was a significant predictor of T1 in patients with pulmonary hypertension (p <?0.001).

Conclusions

Elevated myocardial native T1 was found to a similar extent in pulmonary hypertension patient subgroups and is independently associated with increased interventricular septal angle. Native T1 mapping may not be of additive value in the diagnostic or prognostic evaluation of patients with pulmonary artery hypertension.

     

Views from the field: Medical student experiences and perceptions of interprofessional learning and collaboration in rural settings

Exploring the perceived environment where students are educated, as well as where they practice, is particularly important for educators and practitioners working in situations of interprofessional rural and remote health. In this study, we explored the perceptions of undergraduate medical students regarding interprofessionalism across their four-year undergraduate program which focuses on rural health. A thematic content analysis of the text-data was conducted on a convenience sample of 47 student responses to essay questions across four cohorts of a four-year undergraduate medical program. The medical program has an explicit social accountability mandate for responsiveness to the needs of a rural population and thus students have multiple opportunities to experience interprofessional education and collaboration in rural contexts. Participants reported (a) blurring and flexibility of roles in a primarily positive manner, (b) participating in unstructured interprofessional learning and collaboration, (c) experiencing the importance of social connections to interprofessional collaboration and learning, and (d) realisations that interprofessional collaboration is a means of overcoming barriers in rural areas. We discuss our findings using the socio-material perspective of complexity theory. These findings may be used to inform undergraduate programs in re-defining, re-creating, developing, and fostering interprofessional learning opportunities for medical students in rural communities as well as to support clinical faculty through ongoing professional development.     

National health accounts data from 1996 to 2010: a systematic review

Objective

To collect, compile and evaluate publicly available national health accounts (NHA) reports produced worldwide between 1996 and 2010.

Methods

We downloaded country-generated NHA reports from the World Health Organization global health expenditure database and the Organisation for Economic Co-operation and Development (OECD) StatExtract website. We also obtained reports from Abt Associates, through contacts in individual countries and through an online search. We compiled data in the four main types used in these reports: (i) financing source; (ii) financing agent; (iii) health function; and (iv) health provider. We combined and adjusted data to conform with OECD’s first edition of A system of health accounts manual, (2000).

Findings

We identified 872 NHA reports from 117 countries containing a total of 2936 matrices for the four data types. Most countries did not provide complete health expenditure data: only 252 of the 872 reports contained data in all four types. Thirty-eight countries reported an average not-specified-by-kind value greater than 20% for all data types and years. Some countries reported substantial year-on-year changes in both the level and composition of health expenditure that were probably produced by data-generation processes. All study data are publicly available at http://vizhub.healthdata.org/nha/.

Conclusion

Data from NHA reports on health expenditure are often incomplete and, in some cases, of questionable quality. Better data would help finance ministries allocate resources to health systems, assist health ministries in allocating capital within the health sector and enable researchers to make accurate comparisons between health systems.     

Student support in accelerated nursing programs: Gender-based perspectives and impact on academic outcomes

Background

Factors that contribute to student success in accelerated degree nursing programs are poorly understood and may vary by gender.

Cost-effectiveness analysis of a hospital electronic medication management system

Objective To conduct a cost–effectiveness analysis of a hospital electronic medication management system (eMMS).Methods We compared costs and benefits of paper-based prescribing with a commercial eMMS (CSC MedChart) on one cardiology ward in a major 326-bed teaching hospital, assuming a 15-year time horizon and a health system perspective. The eMMS implementation and operating costs were obtained from the study site. We used data on eMMS effectiveness in reducing potential adverse drug events (ADEs), and potential ADEs intercepted, based on review of 1 202 patient charts before (n = 801) and after (n = 401) eMMS. These were combined with published estimates of actual ADEs and their costs.Results The rate of potential ADEs following eMMS fell from 0.17 per admission to 0.05; a reduction of 71%. The annualized eMMS implementation, maintenance, and operating costs for the cardiology ward were A$61 741 (US$55 296). The estimated reduction in ADEs post eMMS was approximately 80 actual ADEs per year. The reduced costs associated with these ADEs were more than sufficient to offset the costs of the eMMS. Estimated savings resulting from eMMS implementation were A$63–66 (US$56–59) per admission (A$97 740–$102 000 per annum for this ward). Sensitivity analyses demonstrated results were robust when both eMMS effectiveness and costs of actual ADEs were varied substantially.Conclusion The eMMS within this setting was more effective and less expensive than paper-based prescribing. Comparison with the few previous full economic evaluations available suggests a marked improvement in the cost–effectiveness of eMMS, largely driven by increased effectiveness of contemporary eMMs in reducing medication errors.     

Malaria prevalence and associated risk factors in Eritrea

A parasitological cross-sectional survey was undertaken from September 2000 through February 2001 to estimate the prevalence of malaria parasitemia in Eritrea. A total of 12,937 individuals from 176 villages were screened for both Plasmodium falciparum and Plasmodium vivax parasite species using the OptiMal Rapid Diagnostic Test. Malaria prevalence was generally low but highly focal and variable with the proportion of parasitemia at 2.2% (range: 0.4% to 6.5%). Despite no significant differences in age or sex-specific prevalence rates, 7% of households accounted for the positive cases and 90% of these were P. falciparum. Multivariate regression analyses revealed that mud walls were positively associated with malaria infection (OR [odds ratio] = 1.6 [95% CI: 1.2, 2.2], P < 0.008). For countries with low and seasonal malaria transmission, such information can help programs design improved strategic interventions.     

Use of a conductance (volume) catheter and transient inferior vena caval occlusion for rapid determination of pressure-volume relationships in man

Determination of left ventricular pressure-volume relationships in situ ideally requires both a method for easy measurement of multiple pressure-volume loops and a rapid and reversible means of altering load. We report a technique, previously used in animals, that combines conductance catheter volumes and rapid inferior vena caval occlusion to permit routine measurement of calibrated P-V relationships in man for the first time. An 8F volume catheter with a 3F micromanometer tipped pressure catheter placed through its lumen was advanced to the left ventricular apex through a femoral artery. A thermodilution output catheter was placed through a 9F femoral venous sheath and later replaced with an IVC balloon occlusion catheter, through which a 2.5F bipolar wire was advanced for atrial pacing. A specialized data system facilitated collection, editing, and data analysis at the time of cardiac catheterization. Absolute volume calibration required cardiac output measurement and injection of hypertonic saline. IVC occlusion decreased peak left ventricular pressure by 42 +/- 17 (SD) (P less than .001) mm Hg in 15 patients. Endsystolic pressure-volume relationships (ESPVR) were determined with 5-8 cardiac cycles with an average of r2 of 0.94 +/- 0.05 and were generally reproducible. The slope of the ESPVR demonstrated consistency among a group of normal patients (n = 6), and was significantly lower than the slope derived from a group of patients with ventricular hypertrophy (n = 9). We conclude that left ventricular pressure-volume relationships can be easily and repeatedly determined as part of a routine cardiac catheterization in man.     

Overcrowding and understaffing in modern health-care systems: key determinants in meticillin-resistant Staphylococcus aureus transmission

Recent decades have seen the global emergence of meticillin-resistant Staphylococcus aureus (MRSA), causing substantial health and economic burdens on patients and health-care systems. This epidemic has occurred at the same time that policies promoting higher patient throughput in hospitals have led to many services operating at, or near, full capacity. A result has been limited ability to scale services according to fluctuations in patient admissions and available staff, and hospital overcrowding and understaffing. Overcrowding and understaffing lead to failure of MRSA control programmes via decreased health-care worker hand-hygiene compliance, increased movement of patients and staff between hospital wards, decreased levels of cohorting, and overburdening of screening and isolation facilities. In turn, a high MRSA incidence leads to increased inpatient length of stay and bed blocking, exacerbating overcrowding and leading to a vicious cycle characterised by further infection control failure. Future decision making should use epidemiological and economic evidence to evaluate the effect of systems changes on the incidence of MRSA infection and other adverse events.     

Functional assessment of the thyrotropin receptor-beta subunit

Posttranslational processing of the TSH receptor (TSHR) involves proteolysis of a single chain holoreceptor into TSHR-alpha (or A) and TSHR-beta (or B) subunits, which remain associated via disulfide bonds and which may then form oligomers. As both uncleaved and cleavage-derived forms of this receptor have been reported to bind TSH and transduce signals, reasons for this cleavage into alpha- and beta-subunits have remained enigmatic. Recently we suggested that TSHR cleavage was related to receptor oligomerization and now we have asked if cleavage influenced the binding of G proteins to this receptor. Furthermore, as TSHR-alpha subunits are subject to shedding from the cell surface membrane, we have examined whether the remaining TSHR-beta subunits could mediate signaling themselves, either constitutively and /or ligand-induced. We found that only the cleaved form of the TSHR in transfected Chinese hamster ovary cells was able to bind Gsalpha protein, suggesting that cleavage of the native TSH receptor was associated with receptor activation. We also found that independently expressed TSHR-beta subunits on stable cell lines were unable to mediate either constitutive or TSH-induced signaling, as monitored by their inability to induce cAMP accumulation. These data suggested that receptor cleavage was intimately associated with receptor activation in the wild-type TSH receptor and that the residual TSHR-beta subunits left on the thyroid cell membrane, after TSHR cleavage and subsequent TSHR-alpha shedding, were essentially silent and did not participate in signal transduction.