Management of a stenotic right ventricle-pulmonary artery shunt early after the Norwood procedure

BACKGROUND: Inadequate pulmonary blood flow through a right ventricle-to-pulmonary artery (RV-PA) shunt early after the Norwood operation can be remedied by adding a modified Blalock-Taussig (mBT) shunt. We used multiscale computational modeling to determine whether the stenotic RV-PA shunt should be left in situ or removed. METHODS: Models of the Norwood circulation were constructed with (1) a 5-mm RV-PA shunt, (2) a RV-PA shunt with 3- or 2-mm stenosis at the RV anastomosis, (3) a stenotic RV-PA shunt plus a 3.0- or 3.5-mm mBT shunt, or (4) a 3.5-mm mBT shunt. A hydraulic network that mathematically describes an entire circulatory system with pre-stage 2 hemodynamics was used to predict local dynamics within the Norwood circulation. Global variables including total cardiac output, mixed venous oxygen saturation, stroke work, and systemic oxygen delivery can be computed. RESULTS: Proximal stenosis of the RV-PA shunt results in decreased pulmonary blood flow, total cardiac output, mixed venous saturation, and oxygen delivery. Addition of a 3.0- or 3.5-mm mBT shunt leads to pulmonary overcirculation, lowers systemic oxygen delivery, and decreases coronary perfusion pressure. Diastolic runoff through the stenotic RV-PA shunt dramatically increases retrograde flow into the single ventricle. Removal of the stenotic RV-PA shunt balances systemic and pulmonary blood flow, eliminates regurgitant flow into the single ventricle, and improves systemic oxygen delivery. CONCLUSIONS: Adding a mBT shunt to remedy a stenotic RV-PA shunt early after a Norwood operation can lead to pulmonary overcirculation and may decrease systemic oxygen delivery. The stenotic RV-PA shunt should be taken down. Conversion to an optimal mBT shunt is preferable to augmenting a stenotic RV-PA shunt with a smaller mBT shunt

Reducing renal uptake of In-111-DOTATOC: A comparison among various basic amino acids

Purpose: Several studies have reported significant renal toxicity after the use of a high dose of Y-90-DOTATOC. Thus, renal protection is necessary in treatments with Y-90-DOTA Tyr3-octreotide (DOTATOC). The infusion of certain positively charged amino acids has been shown to effectively reduce renal uptake of DOTATOC. In this study, we compared the effectiveness of three kinds of amino acids, D-lysine (lysine), L-arginine (arginine) and histidine, on renal protection in healthy rats and tried to determine which one was the most effective. Methods: Twenty SD healthy male rats were divided into 4 groups: lysine, histidine, arginine, and control. The rats were injected with a dose of 400 mg/kg of amino acid or 2 ml of phosphate-buffered saline (PBS) (as control) intraperitoneally. All rats were sacrificed at 4 hrs after the injection of 1 MBq In-111-DOTATOC. Samples of the kidney were taken and weighed carefully. The counts of radioactivity were measured by a gamma counter and renal concentrations were calculated and expressed as percent injected dose per gram (% ID/g). Results: The renal uptake of In-111-DOTATOC was significantly lower for all three kinds of amino acids when compared to the control group. The renal uptake of In-111-DOTATOC in the lysine group was significantly lower than those in the histidine and arginine groups. The renal uptake of In-111-DOTATOC in the histidine group was lower than that in the arginine group, but no statistical difference was noted. Conclusion: Among these three amino acids, lysine had the best reduction rate of renal uptake of DOTATOC. Histidine was more effective than arginine but no statistical difference was noted

Drinking water turbidity and gastrointestinal illness in the elderly of Philadelphia

STUDY OBJECTIVE—To investigate the association between drinking water quality and gastrointestinal illness in the elderly of Philadelphia.
DESIGN—Within the general population, children and the elderly are at highest risk for gastrointestinal disease. This study investigates the potential association between daily fluctuations in drinking water turbidity and subsequent hospital admissions for gastrointestinal illness of elderly persons, controlling for time trends, seasonal patterns, and temperature using Poisson regression analysis.
SETTING AND PARTICIPANTS—All residents of Philadelphia aged 65 and older in 1992-1993 were studied through their MEDICARE records.
MAIN RESULTS—For Philadelphia's population aged 65 and older, we found water quality 9 to 11 days before the visit was associated with hospital admissions for gastrointestinal illness, with an interquartile range increase in turbidity being associated with a 9% increase (95% CI 5.3%, 12.7%). In the Belmont service area, there was also an association evident at a lag of 4 to 6 days (9.1% increase, 95% CI 5.2, 13.3). Both associations were stronger in those over 75 than in the population aged 65-74. This association occurred in a filtered water supply in compliance with US standards.
CONCLUSIONS—Elderly residents of Philadelphia remain at risk of waterborne gastrointestinal illness under current water treatment practices. Hospitalisations represent a very small percentage of total morbidity.


Keywords: waterborne disease; drinking water; gastrointestinal illness; elderl