Target Flow-Pressure Operating Range for Designing a Failing Fontan Cavopulmonary Support Device

Fontan operation as the current standard of care for the palliation of single ventricle defects results in significant late complications. Using a mechanical circulatory device for the right circulation to serve the function of the missing subpulmonary ventricle could potentially stabilize the failing Fontan circulation. This study aims to elucidate the hydraulic operating regions that should be targeted for designing cavopulmonary blood pumps. By integrating numerical analysis and available clinical information, the interaction of the cavopulmonary support via the IVC and full assist configurations with a wide range of simulated adult failing scenarios was investigated; with IVC and full assist corresponding to the inferior venous return or the entire venous return, respectively, being routed through the device. We identified the desired hydraulic operating regions for a cavopulmonary assist device by clustering all head pressures and corresponding pump flows that result in hemodynamic improvement for each simulated failing Fontan physiology. Results show that IVC support can produce beneficial hemodynamics in only a small fraction of failing Fontan scenarios. Cavopulmonary assist device could increase cardiac index by 35% and decrease the inferior vena cava pressure by 45% depending on the patient\u27s pre-support hemodynamic state and surgical configuration of the cavopulmonary assist device (IVC or full support). The desired flow-pressure operating regions we identified can serve as the performance criteria for designing cavopulmonary assist devices as well as evaluating off-label use of commercially available left-side blood pumps for failing Fontan cavopulmonary support

Scared Straight and Other Juvenile Awareness Programs for Preventing Juvenile Delinquency: A Systematic Review

Programs like ‘Scared Straight’ involve organized visits to prison facilities by juvenile delinquents or children at risk for becoming delinquent. The programs are designed to deter participants from future offending by providing first-hand observations of prison life and interaction with adult inmates. Results of this review indicate that not only does it fail to deter crime but it actually leads to more offending behavior. Government officials permitting this program need to adopt rigorous evaluation to ensure that they are not causing more harm to the very citizens they pledge to protect

Hemodynamic assessment of proposed solutions for Fontan failure

Single ventricle heart defects are among the most severe types of congenital heart problems and require surgical intervention for survival. The common procedure is to use a set of three, staged palliative surgeries to re-route blood around the non-functioning ventricle resuling in a “Fontan” physiology, which connects the vena cave directly to the pulmonary arteries in what is referred to as a total cavopulmonary connection (TCPC). Short term outcomes of this approach are promising, but almost all patients suffer from long term morbities including a variety of issues with the lungs, liver, lymphatics and gastrointestinal system. This thesis focuses on evaluating currently proposed solutions for two of the most common problems faced by Fontan patients: pulmonary arteriovenous malformation (PAVMs) and Fontan associated liver disease (FALD). The use of (1) surgical planning and (2) Y-grafts are hypothesized to offer more balanced hepatic flow distrubtion (HFD), a key factor in PAVM formation. These methods are currently being implemented in a small portion of Fontan patients. In terms of FALD, both (1) improved TCPC efficiency and (2) mechanical circulatory support (MCS) are hypothesized to reduce hepatic congestion and stop or delay the progression of liver disease in these patients. These four proposed solutions were investigated using patient specific computational modeling, medical image analysis, and in vitro testing. A total of ~220 patient data sets were analyzed in this thesis. Four MCS devices were tested. Surgical planning was found to offer accurate HFD predictions for specific graft types and was used to correct PAVMs in several Fontan revision cases. Y-grafts offered similar HFD to traditional connection types at the immediate post-operative state but showed significantly more balanced HFD at ~3 year follow up. TCPC efficiency and LPA stenosis approximately 7 years prior to biopsy were predictive of future liver disease. MCS devices varied in their ability to reduce hepatic congestion, with the more powerful devices being the most successful. Overall, the proposed solutions for both PAVMs and FALD seem to be viable options.Ph.D