Investigating a Novel Activation-Repolarisation Time Metric to Predict Localised Vulnerability to Reentry Using Computational Modelling.

Exit sites associated with scar-related reentrant arrhythmias represent important targets for catheter ablation therapy. However, their accurate location in a safe and robust manner remains a significant clinical challenge. We recently proposed a novel quantitative metric (termed the Reentry Vulnerability Index, RVI) to determine the difference between activation and repolarisation intervals measured from pairs of spatial locations during premature stimulation to accurately locate the critical site of reentry formation. In the clinic, the method showed potential to identify regions of low RVI corresponding to areas vulnerable to reentry, subsequently identified as ventricular tachycardia (VT) circuit exit sites. Here, we perform an in silico investigation of the RVI metric in order to aid the acquisition and interpretation of RVI maps and optimise its future usage within the clinic. Within idealised 2D sheet models we show that the RVI produces lower values under correspondingly more arrhythmogenic conditions, with even low resolution (8 mm electrode separation) recordings still able to locate vulnerable regions. When applied to models of infarct scars, the surface RVI maps successfully identified exit sites of the reentrant circuit, even in scenarios where the scar was wholly intramural. Within highly complex infarct scar anatomies with multiple reentrant pathways, the identified exit sites were dependent upon the specific pacing location used to compute the endocardial RVI maps. However, simulated ablation of these sites successfully prevented the reentry re-initiation. We conclude that endocardial surface RVI maps are able to successfully locate regions vulnerable to reentry corresponding to critical exit sites during sustained scar-related VT. The method is robust against highly complex and intramural scar anatomies and low resolution clinical data acquisition. Optimal location of all relevant sites requires RVI maps to be computed from multiple pacing locations.

Challenges to recruitment and retention of African Americans in the gene-environment trial of response to dietary interventions (GET READI) for heart health.

In this paper, challenges to recruiting African Americans specifically for a dietary feeding trial are examined, learning experiences gained and suggestions to overcome these challenges in future trials are discussed. A total of 333 individuals were randomized in the trial and 234 (167 sibling pairs and 67 parents/siblings) completed the dietary intervention and required DNA blood sampling for genetic analysis. The trial used multiple strategies for recruitment. Hand distributed letters and flyers through mass distribution at various churches resulted in the largest number (n = 153, 46%) of African Americans in the trial. Word of mouth accounted for the second largest number (n = 120, 36%) and included prior study participants. These two recruitment sources represented 82% (n = 273) of the total number of individuals randomized in GET READI. The remaining 18% (n = 60) consisted of a combination of sources including printed message on check stubs, newspaper articles, radio and TV appearances, screening events and presentations. Though challenging, the recruitment efforts for GET READI produced a significant number of African American participants despite the inability to complete the trial as planned because of low recruitment yields. Nevertheless, the recruitment process produced substantial numbers that successfully completed all study requirements.

Community involvement in the conduct of a health education intervention and research project: Community Action Against Asthma.

There is a need for more guidance on how to implement community-based participatory research, particularly on the roles of community members, throughout the process. This article focuses on how a Steering Committee, composed of representatives from community-based organizations, a local health department, an integrated health care system, and academia from the University of Michigan, participated in the design and implementation of a children's asthma study in Detroit, Michigan: Community Action Against Asthma. In addition, this article focuses on the role of community members as data collectors, examining a variety of sophisticated data collection roles. A description and analysis of how community members shaped and participated in the project, the lessons learned, and recommendations for practitioners are also presented.