Experimental Validation of ARFI Surveillance of Subcutaneous Hemorrhage (ASSH) Using Calibrated Infusions in a Tissue-Mimicking Model and Dogs

Acoustic radiation force impulse (ARFI) Surveillance of Subcutaneous Hemorrhage (ASSH) has been previously demonstrated to differentiate bleeding phenotype and responses to therapy in dogs and humans, but to date, the method has lacked experimental validation. This work explores experimental validation of ASSH in a poroelastic tissue-mimic and in vivo in dogs. The experimental design exploits calibrated flow rates and infusion durations of evaporated milk in tofu or heparinized autologous blood in dogs. The validation approach enables controlled comparisons of ASSH-derived bleeding rate (BR) and time to hemostasis (TTH) metrics. In tissue-mimicking experiments, halving the calibrated flow rate yielded ASSH-derived BRs that decreased by 44% to 48%. Furthermore, for calibrated flow durations of 5.0 minutes and 7.0 minutes, average ASSH-derived TTH was 5.2 minutes and 7.0 minutes, respectively, with ASSH predicting the correct TTH in 78% of trials. In dogs undergoing calibrated autologous blood infusion, ASSH measured a 3-minute increase in TTH, corresponding to the same increase in the calibrated flow duration. For a measured 5% decrease in autologous infusion flow rate, ASSH detected a 7% decrease in BR. These tissue-mimicking and in vivo preclinical experimental validation studies suggest the ASSH BR and TTH measures reflect bleeding dynamics

Effect of hawthorn standardized extract on flow mediated dilation in prehypertensive and mildly hypertensive adults: a randomized, controlled cross-over trial

Abstract Background Hawthorn extract has been used for cardiovascular diseases for centuries. Recent trials have demonstrated its efficacy for the treatment of heart failure, and the results of several small trials suggest it may lower blood pressure. However, there is little published evidence to guide its dosing. The blood pressure lowering effect of hawthorn has been linked to nitric oxide-mediated vasodilation. The aim of this study was to investigate the relationship between hawthorn extract dose and brachial artery flow mediated dilation (FMD), an indirect measure of nitric oxide release. Methods We used a four-period cross-over design to evaluate brachial artery FMD in response to placebo or hawthorn extract (standardized to 50 mg oligomeric procyanidin per 250 mg extract). Randomly sequenced doses of hawthorn extract (1000 mg, 1500 mg, and 2500 mg) and placebo were assigned to each participant. Doses were taken twice daily for 3 1/2 days followed by FMD and a 4-day washout before proceeding to the next dosing period. Results Twenty-one prehypertensive or mildly hypertensive adults completed the study. There was no evidence of a dose-response effect for our main outcome (FMD percent) or any of our secondary outcomes (absolute change in brachial artery diameter and blood pressure). Most participants indicated that if given evidence that hawthorn could lower their blood pressure, they would be likely to use it either in conjunction with or instead of lifestyle modification or anti-hypertensive medications. Conclusion We found no evidence of a dose-response effect of hawthorn extract on FMD. If hawthorn has a blood pressure lowering effect, it is likely to be mediated via an NO-independent mechanism. Trial Registration This trial has been registered with ClinicalTrials.gov, a service of the U.S. National Institutes of Health: NCT01331486

Comparison of registered and published outcomes in randomized controlled trials: a systematic review

Abstract Background Clinical trial registries can improve the validity of trial results by facilitating comparisons between prospectively planned and reported outcomes. Previous reports on the frequency of planned and reported outcome inconsistencies have reported widely discrepant results. It is unknown whether these discrepancies are due to differences between the included trials, or to methodological differences between studies. We aimed to systematically review the prevalence and nature of discrepancies between registered and published outcomes among clinical trials. Methods We searched MEDLINE via PubMed, EMBASE, and CINAHL, and checked references of included publications to identify studies that compared trial outcomes as documented in a publicly accessible clinical trials registry with published trial outcomes. Two authors independently selected eligible studies and performed data extraction. We present summary data rather than pooled analyses owing to methodological heterogeneity among the included studies. Results Twenty-seven studies were eligible for inclusion. The overall risk of bias among included studies was moderate to high. These studies assessed outcome agreement for a median of 65 individual trials (interquartile range [IQR] 25–110). The median proportion of trials with an identified discrepancy between the registered and published primary outcome was 31 %; substantial variability in the prevalence of these primary outcome discrepancies was observed among the included studies (range 0 % (0/66) to 100 % (1/1), IQR 17–45 %). We found less variability within the subset of studies that assessed the agreement between prospectively registered outcomes and published outcomes, among which the median observed discrepancy rate was 41 % (range 30 % (13/43) to 100 % (1/1), IQR 33–48 %). The nature of observed primary outcome discrepancies also varied substantially between included studies. Among the studies providing detailed descriptions of these outcome discrepancies, a median of 13 % of trials introduced a new, unregistered outcome in the published manuscript (IQR 5–16 %). Conclusions Discrepancies between registered and published outcomes of clinical trials are common regardless of funding mechanism or the journals in which they are published. Consistent reporting of prospectively defined outcomes and consistent utilization of registry data during the peer review process may improve the validity of clinical trial publications

Risk factors for mortality in adult patients with sickle cell disease: a meta-analysis of studies in North America and Europe

Although recent studies show an improved survival of children with sickle cell disease in the US and Europe, for adult patients mortality remains high. This study was conducted to evaluate the factors associated with mortality in adult patients following the approval of hydroxyurea. We first evaluated the association between selected variables and mortality at an academic center (University of North Carolina). Data sources were then searched for publications from 1998 to June 2016, with meta-analysis of eligible studies conducted in North America and Europe to evaluate the associations of selected variables with mortality in adult patients. Nine studies, combined with the UNC cohort (total n=3257 patients) met the eligibility criteria. Mortality was significantly associated with age (per 10-year increase in age) [7 studies, 2306 participants; hazard ratio (HR): 1.28; 95% confidence interval (CI): 1.10–1.50], tricuspid regurgitant jet velocity 2.5 m/s or more (5 studies, 1577 participants; HR: 3.03; 95%CI: 2.0–4.60), reticulocyte count (3 studies, 1050 participants; HR: 1.05; 95%CI: 1.01–1.10), log(N-terminal-pro-brain natriuretic peptide) (3 studies, 800 participants; HR: 1.68; 95%CI: 1.48–1.90), and fetal hemoglobin (7 studies, 2477 participants; HR: 0.97; 95%CI: 0.94–1.0). This study identifies variables associated with mortality in adult patients with sickle cell disease in the hydroxyurea era

Hemodynamic Characteristics and Predictors of Pulmonary Hypertension in Patients With Sickle Cell Disease

Pulmonary hypertension (PH) is a common comorbidity of sickle cell disease (SCD) with an associated increased mortality risk, but its etiology is not well-understood. To evaluate the hemodynamic characteristics, clinical predictors, and cardiovascular manifestations of elevated pulmonary arterial pressure in this population, we performed noninvasive hemodynamic assessments of 135 patients with SCD using Doppler echocardiography. A diagnosis of PH was based on gender-, age-, and body mass index (BMI)-specific normal reference ranges for tricuspid regurgitation jet velocities (TRV). A high TRV was noted in 34 (25%) of patients. Pulmonary vascular resistance (PVR) was elevated in only 2 of the 34 patients (6%) with suspected PH, but was significantly higher than in those with a normal TRV. In univariate regression, TRV correlated with age, BMI, left atrial pressure, and right ventricular stroke volume, and was negatively associated with hemoglobin and glomerular filtration rate. Left atrial pressure, right ventricular stroke volume, and hemoglobin remained independent predictors of TRV in a multivariate model. A higher TRV was also associated with larger right ventricular and right atrial chamber sizes and higher N-terminal pro-brain natriuretic peptide levels. Our results suggest that the mild elevation in TRV often observed in patients with SCD is rarely associated with a high PVR, and that multiple factors – including the compensatory high output state associated with anemia, pulmonary venous hypertension, and a pulmonary vasculopathy – may contribute to an elevated pulmonary arterial pressure in these patients

Longitudinal study of echocardiography-derived tricuspid regurgitant jet velocity in sickle cell disease

Although echocardiography-derived tricuspid regurgitant jet velocity (TRV) is associated with increased mortality in sickle cell disease (SCD), its rate of increase and predictive markers of its progression are unknown. We evaluated 55 subjects (median age: 38 years, range: 20 – 65 years) with at least 2 measurable TRVs, followed for a median of 4.5 years (range: 1.0 – 10.5 years) in a single-centre, prospective study. Thirty-one subjects (56%) showed an increase in TRV, while 24 subjects (44%) showed no change or a decrease in TRV. A linear mixed effects model indicated an overall rate of increase in the TRV of 0.02 m/s per year (p = 0.023). The model showed that treatment with hydroxycarbamide was associated with an initial TRV that was 0.20 m/s lower than no such treatment (p = 0.033), while treatment with angiotensin converting enzyme inhibitors and inhibitors/ angiotensin receptor blockers was associated with an increase in the TRV (p = 0.006). In summary, although some patients have clinically meaningful increases, the overall rate of TRV increase is slow. Treatment with hydroxycarbamide may decrease the progression of TRV. Additional studies are required to determine the optimal frequency of screening echocardiography and the effect of therapeutic interventions on the progression of TRV in SCD

Associations Between Echocardiographic Arterial Compliance and Incident Cardiovascular Disease in Blacks: The ARIC Study

Systemic arterial compliance is sometimes derived by echocardiographic stroke volume to pulse pressure ratios. Few studies have assessed echocardiographic arterial compliance in blacks or its associations with explicit, rather than composite, cardiovascular disease (CVD) outcomes

Outcomes of Patients With Anemia and Acute Decompensated Heart Failure With Preserved Versus Reduced Ejection Fraction (from the ARIC Study Community Surveillance)

Anemia is associated with poor prognosis in patients hospitalized with acute decompensated heart failure (ADHF). Whether the impact of anemia differs by heart failure with preserved (HFpEF) or reduced (HFrEF) ejection fraction is uncertain. We examined hospital surveillance data captured by the Atherosclerosis Risk in Communities Study from January 1, 2005 – December 31, 2010. Diagnoses of ADHF were validated by standardized physician review of the medical record. Anemia was classified using WHO criteria (<12 g/dL for women, < 13 g/dL for men), and heart failure type was determined by the ejection fraction (<40% for HFrEF, ≥ 40% for HFpEF). Hospital length of stay and 1-year mortality outcomes were analyzed by multivariable regression, weighted to account for the sampling design, and adjusted for demographics and clinical covariates. Over 6 years, 15,461 (weighted) hospitalized events for ADHF (59% HFrEF) occurred in the ARIC catchment, based on 3,309 sampled events. Anemia was associated with a mortality hazard ratio of 2.1 (95% CI: 1.6 – 2.7) in patients classified with HFpEF, and 1.4 (95% CI: 1.1 – 1.7) among those with HFrEF; p for interaction = 0.05. The mean increase in length of hospital stay associated with anemia was 3.5 days (95% CI: 3.4 – 3.6) for patients with HFpEF, compared with 1.8 days (95% CI: 1.7 – 1.9) for those with HFrEF; p for interaction <0.0001. In conclusion, the incremental risks of death and lengthened hospital stay associated with anemia are more pronounced in ADHF patients classified with HFpEF than HFrEF

ARFI Ultrasound Monitoring of Hemorrhage and Hemostasis In Vivo in Canine Von Willebrand Disease and Hemophilia

A validated method for assessing hemostasis in vivo is critical for testing the hemostatic efficacy of therapeutic agents designed for patients with bleeding disorders such as von Willebrand disease (VWD) and hemophilia A. We hypothesize that rate of bleeding and time to hemostasis can be monitored in vivo by acoustic radiation force impulse (ARFI) ultrasound. We performed ARFI imaging following 12-gauge needle puncture of hind limb muscle encompassing an ~2mm vein in six normal, eight naïve hemophilia A before and after infusing canine factor VIII, three hemophilia A expressing canine factor VIIa following gene transfer, and two naïve VWD dogs. Serial data sets were processed with custom software to (1) estimate the rate of hemorrhage and (2) estimate the time of hemostasis onset. The rate of hemorrhage during the first 30 min following puncture was markedly increased in the VWD dogs relative to normal but was not significantly different between normal, naïve hemophilia A or hemophilia A expressing cFVIIa. ARFI-derived times to hemostasis were significantly longer in naïve hemophilia A dogs than in normal dogs and were shortened by canine coagulation factors VIII and VIIa. These data support our hypothesis that rate of hemorrhage and time to hemostasis in vivo in response to a standardized hemostatic challenge can be detected by ARFI ultrasound in canine models of VWD and hemophilia. These data also suggest that the ARFI-monitored hemostatic challenge is relevant for in vivo testing of the hemostatic efficacy of therapeutic clotting factor replacement products used to treat inherited bleeding disorders

Sickle Cell Trait and Incident Ischemic Stroke in the Atherosclerosis Risk in Communities Study

Numerous case reports describe stroke in individuals with sickle cell trait (SCT) in the absence of traditional risk factors for cerebrovascular disease. To date, no prospective epidemiological studies have investigated this association