Improvement of heat transfer within phase change materials using V-shaped rods.

This study numerically investigated the improvement of heat transmission to phase change material (PCM) paraffin wax in a triangular cell with and without fins. The enthalpy-porosity combination was quantitatively evaluated using the ANSYS/FLUENT 20 program. Materials with the phase shifts of paraffin wax were used in this study (RT42). According to the study findings, fins significantly accelerate the melting process and decrease the time required to finish it. The time difference between melting with and without fins is 125%. Moreover, the inclusion of v-shaped fins contributed to a 200% reduction in the melting process time. Thus, the use of v-shaped fins facilitates faster heat transfer to and from the applications wherein the phase change materials are used.

Del nido cardioplegia in adults: a retrospective observational study in comparison to modified St. Thomas cardioplegia in cardiac surgery.

BACKGROUND: St. Thomas cardioplegia is commonly administered to adults, yet repeated dosing at brief intervals is required. Del Nido's cardioplegic solution provides a prolonged duration of safe myocardial arrest, yet it was primarily intended for pediatric cardiac surgery. Recently, there has been an increasing interest in using Del Nido's in adults; this might be due to its ease of administration and extended re-dosing intervals. This study contrasted Del Nido's to modified St. Thomas cardioplegia in adults. METHODS: This study was conducted on 200 patients. Troponin-T was the primary outcome within the first 24 and 48 h post-surgery. Cardiopulmonary bypass time, cross-clamp time, intraoperative use of inotropic support, defibrillator and/or intra-aortic balloon were the secondary outcomes of the study. RESULTS: There was a significant reduction in post-operative Troponin-T levels in the first 24 and 48 h within Del Nido's group compared to the modified St. Thomas group. The cross-clamp and cardiopulmonary bypass times were also found to be lower within Del Nido's group. CONCLUSION: This study has demonstrated a significant reduction in early postoperative Troponin-T levels as well as operative times favoring Del Nido's in adults.

Total Correction of Tetralogy of Fallot in the First 60 Days of Life in Symptomatic Infants: Is It The Gold Standard?

BACKGROUND: The timing of surgical repair of tetralogy of Fallot (TOF) is a key to alleviate complications and for long-term survival. Total correction was usually performed at the age of 6 months or older under the notion of decreasing the surgical risk. However, avoiding palliation with an aortopulmonary shunt and early correction of systemic hypoxia appear to be of more benefit than the inborn surgical risk in low body weight patients. Our objective was to assess early/midterm survival and operative complications and to analyze patients, surgical techniques, and morphological risk factors to determine their effects on outcomes. PATIENTS AND METHODS: We retrospectively reviewed 152 patients with TOF who were ≤60 days of age when they underwent total correction of TOF. All patients had either duct-dependent pulmonary blood flow or arterial blood oxygen saturation less than 65% on room air requiring urgent surgical correction. Exclusion criteria included TOF with pulmonary atresia, TOF with nonconfluent pulmonary arteries, TOF with multiple aortopulmonary collateral arteries, and associated complete atrioventricular septal defects. RESULTS: The mean age at repair was 34 ± 19 days, and the mean weight was 3.8 ± 0.9 kg. Before surgery, 96 patients received an infusion of prostaglandin, 45 were mechanically ventilated, and 32 required inotropic support. Right ventricular outflow tract obstruction was managed with a transannular patch in 112 patients, and all the others had a main pulmonary artery patch. Cardiopulmonary bypass (CPB) with moderate hypothermia was the standard, and the CPB time averaged 48 ± 21 minutes. The postoperative intensive care unit stay was 5.7 ± 6 days, with 2.8 ± 4 days of mechanical ventilation. Early mortality was 4.6% (7 of 152), and actuarial survival rates were 95% at 1 year and 92% at 5 years. Univariable and multivariable analyses of the patients' demographics, anatomical characteristics, and operative techniques revealed the presence of small pulmonary arteries and low body weight to be the only independent risk factors for death. CONCLUSION: Early total correction of TOF during the first 60 days of life can be performed with low mortality and good intermediate-term survival and, from our point of view, "should be the gold standard for TOFs."