Characterization of a highly effective preparation for suppression of myocardial glucose utilization.

BACKGROUND: With appropriate protocols, F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) can visualize myocardial inflammation. Optimal protocols and normative myocardial FDG uptake values are not well-established. METHODS: We evaluated 111 patients referred for inflammation cardiac FDG PET/CT. Patients followed a low-carbohydrate, high-fat diet for 36 hours before imaging and received unfractionated heparin. Glucose and fatty acid metabolism biomarkers were obtained. Mean blood pool and maximum myocardial uptake (SUVmean, SUVmax) were measured, avoiding areas of abnormal FDG uptake or spillover. RESULTS: Adequate suppression of myocardial FDG uptake occurred in 95% of patients (n = 106). Myocardial SUVmax was significantly below background blood pool SUVmean: septal myocardial to blood pool ratio 0.75 (95% CI 0.73-0.77; P < 0.001); lateral myocardial to blood pool ratio 0.70 (95% CI 0.68-0.72; P < 0.001). Glucose, insulin, and C-peptide correlated to blood pool SUVmean (Spearman rs = 0.39, P < 0.01; rs = 0.40, P < 0.01; rs = 0.35, P < 0.01) and myocardial SUVmax (Spearman rs = 0.31, P < 0.01; rs = 0.31, P < 0.01; rs = 0.26, P < 0.01). Fatty acid metabolism biomarkers did not correlate to myocardial SUVmax. CONCLUSIONS: Patients following intensive metabolic preparation have myocardial FDG SUVmax below background SUVmean. Biomarkers of glucose metabolism modestly correlate to FDG uptake.

Large-Scale Variability of Inpatient Tacrolimus Therapeutic Drug Monitoring at an Academic Transplant Center: A Retrospective Study.

BACKGROUND: Inpatient tacrolimus therapeutic drug monitoring (TDM) lacks standardized guidelines. In this study, the authors analyzed variability in the preanalytical phase of the inpatient tacrolimus TDM process at their institution. METHODS: Patients receiving tacrolimus (twice-daily formulation) and tacrolimus laboratory analysis were included in the study. Times of tacrolimus administration and laboratory study collection were extracted, and time distribution plots for each step in the inpatient TDM process were generated. RESULTS: Trough levels were drawn appropriately in 25.9% of the cases. Timing between doses was consistent, with 91.9% of the following dose administrations occurring 12 ± 2 hours after the previous dose. Only 38.1% of the drug administrations occurred within 1 hour of laboratory study collection. Tacrolimus-related patient safety events were reported at a rate of 1.9 events per month while incorrect timing of TDM sample collection occurred approximately 200 times per month. Root cause analysis identified a TDM process marked by a lack of communication and coordination of drug administration and TDM sample collection. Extrapolating findings nationwide, we estimate $22 million in laboratory costs wasted annually. CONCLUSIONS: Based on this large single-center study, the authors concluded that the inpatient TDM process is prone to timing errors, thus is financially wasteful, and at its worst harmful to patients due to clinical decisions being made on the basis of unreliable data. Further work is needed on systems solutions to better align the laboratory study collection and drug administration processes.

Histamine H2 Receptor Antagonists and Heart Failure Risk in Postmenopausal Women: The Women's Health Initiative.

Background Prior studies suggested lower risk of heart failure (HF) in individuals taking H2 receptor antagonists (H2RA) compared with H2RA nonusers in relatively small studies. We evaluated the association of H2RA use and incident HF in postmenopausal women in the large-scale WHI (Women's Health Initiative) study. Methods and Results This study included postmenopausal women from the WHI without a history of HF at baseline. HF was defined as first incident hospitalization for HF and physician adjudicated. Multivariable Cox proportional hazards regression models evaluated the association of H2RA use as a time-varying exposure with HF risk, after adjustment for demographic, lifestyle, and medical history variables. Sensitivity analyses examined (1) risk of HF stratified by the ARIC (Atherosclerosis Risk in Communities) score, (2) propensity score matching on H2RA use, (3) use of proton pump inhibitors rather than H2RA nonuse as the referent, and (4) exclusion of those taking diuretics at baseline. The primary analysis included 158 854 women after exclusion criteria, of whom 9757 (6.1%) were H2RA users. During median 8.2 years of follow-up, 376 H2RA users (4.9 events/1000 person-years) and 3206 nonusers (2.7 events/1000 person-years) developed incident HF. After multivariable adjustment, there was no association between H2RA use and HF in the primary analysis (hazard ratio, 1.07; 95% CI, 0.94-1.22; P=0.31) or in any of the sensitivity analyses. Conclusions Clinical H2RA use was not associated with incident HF among postmenopausal women. Future studies are needed to evaluate potential effect modification by sex, HF severity, or patterns of use on H2RA exposure and HF risk. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00000611.

Platypnea Orthodeoxia Syndrome Secondary to Intracardiac Shunt Following Orthotopic Liver Transplantation.

Platypnea orthodeoxia syndrome (POS) occurs when an upright position results in acute-onset hypoxemia and is relieved with recumbency. POS can be due to intracardiac shunting, intrapulmonary shunting, ventilation-perfusion mismatch, or a combination of these. We report a case of POS that developed 3 days post liver transplantation as a result of new-onset right to left shunting across a patent foramen ovale. Right heart catheterization revealed a posteriorly directed inferior vena cava likely due to altered inferior vena cava-right atrial junction anatomy as a result of liver transplantation. The patient underwent successful transcatheter patent foramen ovale closure with a 25-mm Gore Cardioform septal occluder device with immediate and sustained improvement in hypoxia.

Ischemic preconditioning improves oxygen saturation and attenuates hypoxic pulmonary vasoconstriction at high altitude.

Exposure to hypoxic environments is associated with decreased arterial oxygen saturation and increased pulmonary artery pressures. Ischemic preconditioning of an extremity (IPC) is a procedure that stimulates vasoactive and inflammatory pathways that protect remote organ systems from ongoing or future ischemic injury. To test the effects of IPC on oxygen saturation and pulmonary artery pressures at high altitude, 12 healthy adult volunteers were evaluated in a randomized cross-over trial. IPC was administered utilizing a standardized protocol. IPC or placebo was administered daily for 5 days prior to ascent to altitude. All participants were evaluated twice at 4342 m altitude (placebo and IPC conditions separated by 4 weeks, randomized). The pulmonary artery systolic pressure (PASP) at 4342 m was significantly lower in the IPC condition than the placebo condition (36 ± 6.0 mmHg vs. 38.1 ± 7.6 mmHg, respectively, p = 0.035). Oxygen saturation at 4342 m was significantly higher with IPC compared to placebo (80.3 ± 8.7% vs. 75.3 ± 9.6%, respectively, p = 0.003). Prophylactic IPC treatment is associated with improved oxygen saturation and attenuation of the normal hypoxic increase in pulmonary artery pressures following ascent to high altitude.

Pre-condicionamiento isquémico mejora saturación de oxígeno y atenúa vasoconstricción pulmonar por hipoxia a gran altura / Ischemic pre-conditioning improves oxygen saturation and attenuates pulmonary vasoconstriction due to high-altitude hypoxia

La exposición a ambientes de hipoxia, está asociada con una disminución de la saturación arterial de oxígeno y el aumento de las presiones de la arteria pulmonar. El pre-condicionamiento isquémico de una extremidad (IPC Ischemic Preconditioning), es un procedimiento que estimula las vías vasoactiva e inflamatoria, que protegen los sistemas de órganos remotos, de daño isquémico. Para evaluar los efectos de IPC, en la saturación de oxígeno y presiones de la arteria pulmonar, a gran altura; fueron evaluados 12 voluntarios adultos sanos, en un ensayo aleatorio randomizado cruzado (randomized cross-over trial). El IPC fue realizado, utilizando un protocolo estandarizado. Se realizó IPC o placebo diariamente, durante 5 días previos al ascenso a gran altura. Todos los participantes fueron evaluados dos veces a 4243 m de altura (en condiciones de IPC y placebo, con un intervalo de 4 semanas, aleatorizados). La presión sistólica de la arteria pulmonar (PASP) a 4342 m fue significativamente menor en condiciones de IPC, que en condiciones de placebo (36±6.0 mmHg vs. 38.1±7.6 mmHg, respectivamente, p=0.0035). La saturación de oxígeno a 4342 m fue significativamente más elevada en IPC en comparación con placebo (80.3±8.7 por ciento vs. 75.3±9.6 por ciento, respectivamente, p-0.003). IPC como tratamiento profiláctico está asociado con una saturación de oxígeno mayor y atenuación del incremento normal de la presión de arteria pulmonar por hipoxia, seguida al ascenso a gran altura.