Emissions and energy impacts of the Inflation Reduction Act

Economy-wide emissions drop 43 to 48% below 2005 levels by 2035 with accelerated clean energy deployment.

Actions for reducing US emissions at least 50% by 2030

Policies must help decarbonize power and transport sectors.

Work and well-being: collective and individual self-concept, job commitment, citizenship behavior, and autonomy as predictors of overall life satisfaction

A job may contribute to overall life satisfaction (LS) when it meets basic psychological needs. This study examined aspects of one's work (organizational commitment, citizenship behavior and autonomy), and individual differences in self-concept (collective versus individual), as predictors of overall LS. 295 employees working at a variety of jobs completed questionnaires online. Results showed that higher collective self-concept predicted greater LS; this was partially mediated by affective job commitment, work autonomy and altruistic citizenship behaviors, all of which also independently predicted greater LS. Higher individual self-concept was also a significant predictor of LS, partially mediated by compliance citizenship behaviors. These results suggest that when work fulfills a need for connectedness (i.e., for people with a collective self-concept), autonomy, and when we feel emotionally committed to our job, and go beyond what it requires, our overall LS is higher. These results clarify some positive ways that our work contributes to overall LS, but important questions remain for future research.

P920Understanding arrhythmia mechanisms in patients with atrial septal defects

Background

Atrial arrhythmias represent a major cause of morbidity and hospitalization in patients with atrial septal defects (ASD). Optimum treatment strategies are unknown since the mechanisms of arrhythmia are undefined in this cohort.

Purpose

We investigated whether percutaneous ASD closure reduces atrial arrhythmias and subsequently examined the electrical and structural changes underpinning arrhythmogenesis in ASD patients.

Methods

Meta-analysis was used to study the effect of closure on arrhythmias. Bi-atrial electrical dysfunction was assessed through invasive measurement of atrial voltage, refractory periods (ERP) over three drive trains (600, 450 and 300ms) and local conduction velocity (CV) with subsequent assessment of ERP and CV restitution. Structural remodelling was assessed through non-invasive quantification of fibrosis using cardiac MRI (CMR). Origin of ectopy was evaluated invasively using isoprenaline infusion and non-invasively using 24-hour Holter monitoring. Comparison was made to normal heart controls.

Results

Meta-analysis

Meta-analysis of 25 studies found that percutaneous closure was associated with a weak reduction in atrial arrhythmias only in patients >40 years old (OR 0.777, 95% CI 0.616-0.979, P = 0.032).

Electrical Remodelling

On invasive assessment (21 ASDs; 21 controls), proportion of right atrial low voltage (<0.5mV) and scar (<0.05mV) was greater in ASD vs control patients (P = 0.02 and P = 0.039). In ASD patients, these parameters were greater in the right atrium vs the left atrium (P = 0.002 and P = 0.01). Right atrial ERP restitution slopes were steeper in ASD vs control patients (P = 0.016). Maximum right atrial CV and CV restitution slopes were greater in ASD vs control patients (P= 0.005 and P < 0.001 respectively) and CV decrement occurred at longer coupling intervals in the right atrium in ASD patients (P = 0.015).

Structural Remodelling

On CMR assessment (36 ASDs; 36 controls), bi-atrial fibrosis was greater in ASD vs control patients (P < 0.001). In ASD patients right atrial fibrosis was burden greater in patients with vs without atrial arrhythmias (P = 0.034).

Arrhythmia Triggers

On 24-hour Holter monitoring and during invasive isoprenaline infusion right and left atrial ectopy was equally prevalent in ASD vs control patients.

Conclusion

This study highlights the importance of right atrial electrical dysfunction to the occurrence of arrhythmias in ASD patients with extensive right atrial remodelling (fibrosis, low voltage, steeper ERP and CV restitution) seen in ASD patients compared to normal heart controls.

From the results of the meta-analysis it appears that percutaneous closure alone is insufficient to treat arrhythmias in ASD patients. Given the predominance of right atrial remodelling, right-sided ablation as an adjunct to conventional left-sided ablation should be investigated as a strategy to treat atrial arrhythmias in these patients.

Abstract Figure.

4969Enhanced gap junction coupling organised and terminated acute ventricular fibrillation in ex-vivo perfused hearts

Background

The underlying mechanism of ventricular fibrillation (VF) remains unclear. There are both experimental and clinical data to support the existence of rotational drivers (RDs), though other opposing studies suggest that VF is the result of disorganized myocardial activation. Abnormal electrical coupling between cardiomyocytes through gap junctions (GJ) has been considered an important factor in the genesis and maintenance of VF and pre-treatment with GJ couplers, rotigaptide (RTG), has been shown to reduce VF inducibility.

Purpose

We hypothesized that the degree of GJ coupling determines the underlying mechanism of VF, and that changes in GJ coupling can shift or modify the predominant mechanism of fibrillation along the spectrum between disorganised activity and organised drivers. We proposed that increased organisation of VF is critical to its termination.

Methods

Thirty Sprague-Dawley rat hearts were explanted, perfused ex-vivo and acute VF was induced with burst pacing and 30μM pinacidil. Optical mapping of transmembrane potential was performed at baseline and the effects of GJ coupling on VF dynamics were studied in an acute VF model by perfusing with increasing concentrations of a GJ uncoupler; carbenoxolone (0–50μM, CBX, n=10) or a GJ coupling-enhancer; RTG (0–80nM, n=10). A chronic diffuse fibrosis model (n=10) was generated with 4 weeks of in-vivo angiotensin infusion (500nm/kg/min). Fibrillation dynamics were quantified using phase analysis, phase singularity (PS) tracking and our novel method of global fibrillation organisation quantification, frequency dominance index (FDI), which is a power ratio of highest amplitude dominant frequency in the frequency spectrum.

Results

RTG increased average rotations per RD (Baseline: 2.86±0.10 vs 80nM: 5.66±0.43, p<0.001) whilst CBX caused a reduction (Baseline: 3.77±0.39 vs 50μM: 0.26±0.26, p<0.001). Maximum rotations for a RD increased with RTG (5.4±0.45 vs 48.20±12.32, p<0.001) and decreased with CBX (8.0±1.3 vs 0.3±0.3, p<0.001). Proportion of time PSs were detected in VF increased with RTG (0.44±0.06 vs 0.93±0.02, p<0.001) and decreased with CBX (0.61±0.9 vs 0.03±0.02, p<0.001). RTG reduced meander of longest duration RD (20.6±1.68 vs 11.51±0.77 pixels, p<0.001) for PS >5 rotations. FDI increased with RTG (0.53±0.04 vs 0.78±0.3, p<0.001) and decreased with CBX (0.60±0.05 vs 0.17±0.03, p<0.001). In the diffuse fibrosis group, in comparison to baseline RTG 80nM increased FDI (0.35 vs 0.65, p<0.001) and terminated VF in 40% of hearts.

Conclusion

The degree of GJ coupling is a key determinant of the underlying mechanism of VF. RTG organised fibrillation and stabilised RDs in a concentration-dependent manner whilst CBX disorganised VF. Enhancing GJ coupling with RTG in diseased hearts with fibrosis can terminate VF and may be a potential therapeutic target in acute VF.

Acknowledgement/Funding

BHF Programme Grant PG/16/17/32069

Physicians plan for change with clearly defined goals

A goal-setting approach to medical staff activity has helped the medical staff at San Jose Hospital to define their relationships with hospital administrators, patients, hospital personnel, and with the community. For the first time, the medical staff has a clear set of standards against which to measure their performance.