Paul A. Harris

Research electronic data capture (REDCap)-A metadata-driven methodology and workflow process for providing translational research informatics support

Research electronic data capture (REDCap) is a novel workflow methodology and software solution designed for rapid development and deployment of electronic data capture tools to support clinical and translational research. We present: (1) a brief description of the REDCap metadata-driven software toolset; (2) detail concerning the capture and use of study-related metadata from scientific research teams; (3) measures of impact for REDCap; (4) details concerning a consortium network of domestic and international institutions collaborating on the project; and (5) strengths and limitations of the REDCap system. REDCap is currently supporting 286 translational research projects in a growing collaborative network including 27 active partner institutions.

Chronic orthostatic intolerance: a disorder with discordant cardiac and vascular sympathetic control.

BACKGROUND Chronic orthostatic intolerance (COI) is a debilitating autonomic condition in young adults. Its neurohumoral and hemodynamic profiles suggest possible alterations of postural sympathetic function and of baroreflex control of heart rate (HR). METHODS AND RESULTS In 16 COI patients and 16 healthy volunteers, intra-arterial blood pressure (BP), ECG, central venous pressure (CVP), and muscle sympathetic nerve activity (MSNA) were recorded at rest and during 75 degrees tilt. Spectral analysis of RR interval and systolic arterial pressure (SAP) variabilities provided indices of sympathovagal modulation of the sinoatrial node (ratio of low-frequency to high-frequency components, LF/HF) and of sympathetic vasomotor control (LFSAP). Baroreflex mechanisms were assessed (1) by the slope of the regression line obtained from changes of RR interval and MSNA evoked by pharmacologically induced alterations in BP and (2) by the index alpha, obtained from cross-spectral analysis of RR and SAP variabilities. At rest, HR, MSNA, LF/HF, and LFSAP were higher in COI patients, whereas BP and CVP were similar in the two groups. During tilt, BP did not change and CVP fell by the same extent in the 2 groups; the increase of HR and LF/HF was more pronounced in COI patients. Conversely, the increase of MSNA was lower in COI than in control subjects. Baroreflex sensitivity was similar in COI and control subjects at rest; tilt reduced alpha similarly in both groups. CONCLUSIONS COI is characterized by an overall enhancement of noradrenergic tone at rest and by a blunted postganglionic sympathetic response to standing, with a compensatory cardiac sympathetic overactivity. Baroreflex mechanisms maintain their functional responsiveness. These data suggest that in COI, the functional distribution of central sympathetic tone to the heart and vasculature is abnormal.

A common β1-adrenergic receptor polymorphism (Arg389Gly) affects blood pressure response to β-blockade

A common polymorphism of the β1‐adrenergic receptor Arg389Gly markedly affects function in vitro, but little is known about its in vivo significance.

Water Ingestion as Prophylaxis Against Syncope

Background—Water ingestion raises blood pressure substantially in patients with perturbed autonomic control and more modestly in older subjects. It is unclear whether prophylactic water drinking improves orthostatic tolerance in normal healthy adults. Methods and Results—Twenty-two healthy subjects, 18 to 42 years of age, with no history of syncope underwent head-up tilt-table testing at 60° for 45 minutes or until presyncope or syncope occurred. In their initial test, participants were randomized to either 16 oz (473 mL) of water drinking 5 minutes before tilt-table testing or tilt-table testing alone, with the alternative in a second test on a different day. During the first 30 minutes of tilt, 8 of 22 subjects without water experienced presyncope but only 1 of 22 who had ingested water (P =0.016). Water drinking attenuated the heart rate increase associated with tilt (P <0.001) while accentuating the increase in total peripheral resistance (P =0.012). The average time study participants tolerated head-up tilt was 26% longer after water (41.1±8.1 versus 32.6±14.3 minutes, mean±SD), with a pairwise mean difference of 8.5±14.0 minutes (95% CI, 2.3 to 14.7 minutes; P =0.011). Conclusions—Water enhances tolerance of upright posture. The effect of water is mediated by increased peripheral vascular resistance. Water ingestion may constitute a simple and effective prophylaxis against vasovagal reactions in healthy subjects, such as those associated with blood donation.

Arg389Gly β1-adrenoceptor polymorphism varies in frequency among different ethnic groups but does not alter response in vivo

There are marked interethnic differences in beta 1-adrenoceptor-mediated responsiveness, with sensitivity decreased in African-Americans and increased in Chinese compared with Caucasians. Therefore, the frequency of a common naturally occurring polymorphism of the human beta 1-adrenoceptor gene (Arg389Gly), which has functional importance in vitro, was determined in 194 African-Americans, 316 Caucasian-Americans, 221 Hispanic-Americans and 142 Chinese. African-Americans were found to have a significantly lower frequency of the Arg389 allele than the other three ethnic groups (all P < 0.01). In the populations studied, the order of the distribution of the Arg389 allele was: Chinese (74%) > Caucasians (72%) > Hispanics (67%) > African-Americans (58%). To determine the functional significance of the Arg389Gly beta 1-adrenoceptor polymorphism, in-vivo heart rate responses to exercise were compared in healthy subjects homozygous for the Arg (n = 9) and Gly (n = 8) alleles. Heart rate response to exercise was not affected by genotype (P = 0.4). Although ethnic differences in the frequency of the beta 1-adrenoceptor Arg389Gly polymorphism exist, the polymorphism does not appear to have functional significance in healthy subjects and therefore may not contribute to ethnic differences in response to drugs acting through the beta 1-adrenoceptor.

Acetylcholinesterase Inhibition Improves Tachycardia in Postural Tachycardia Syndrome

Background—Postural tachycardia syndrome (POTS) induces disabling chronic orthostatic intolerance notable for an excessive increase in heart rate that occurs on standing. Many current therapeutic strategies focus on sympatholysis, but the alternative strategy of enhancing cardiovagal tone has not been studied. The objective of this study was to test the hypothesis that acetylcholinesterase inhibitors will attenuate the tachycardia and improve symptom burden in patients with POTS. Methods and Results—Seventeen patients with POTS underwent acute drug trials of pyridostigmine 30 mg orally and placebo, on separate mornings, in a randomized crossover design. Blood pressures, heart rate, and symptoms were assessed while patients were seated and after they had been standing for up to 10 minutes both before the study drug was given and at 2 and 4 hours after study drug. The heart rate was significantly lower at 2 hours after pyridostigmine than after placebo (100±16 versus 111±14 bpm, P=0.001). Pyridostigmine significantly decreased the standing heart rate from baseline (119±16 bpm) at 2 hours (104±16 bpm, P<0.001) and 4 hours (100±16 bpm, P<0.001) after administration. There was no significant change in blood pressure. The decrease in symptom burden within 4 hours after study drug was significantly greater with pyridostigmine than placebo (−10.4±14.0 AU versus 0.6±7.5 AU, P<0.025). Conclusions—Acute acetylcholinesterase inhibition significantly attenuated tachycardia in POTS. There was also an improvement in symptom burden with this promising therapy.

Hyperadrenergic Postural Tachycardia Syndrome in Mast Cell Activation Disorders

Postural tachycardia syndrome (POTS) is a disabling condition that commonly affects otherwise normal young females. Because these patients can present with a flushing disorder, we hypothesized that mast cell activation (MCA) can contribute to its pathogenesis. Here we describe POTS patients with MCA (MCA+POTS), diagnosed by episodes of flushing and abnormal increases in urine methylhistamine, and compared them to POTS patients with episodic flushing but normal urine methylhistamine and to normal healthy age-matched female controls. MCA+POTS patients were characterized by episodes of flushing, shortness of breath, headache, lightheadedness, excessive diuresis, and gastrointestinal symptoms such as diarrhea, nausea, and vomiting. Triggering events include long-term standing, exercise, premenstrual cycle, meals, and sexual intercourse. In addition, patients were disabled by orthostatic intolerance and a characteristic hyperadrenergic response to posture, with orthostatic tachycardia (from 79±4 to 114±6 bpm), increased systolic blood pressure on standing (from 117±5 to 126±7 mm Hg versus no change in POTS controls), increased systolic blood pressure at the end of phase II of the Valsalva maneuver (157±12 versus 117±9 in normal controls and 119±7 mm Hg in POTS; P=0.048), and an exaggerated phase IV blood pressure overshoot (50±10 versus 17±3 mm Hg in normal controls; P<0.05). In conclusion, MCA should be considered in patients with POTS presenting with flushing. These patients often present with a typical hyperadrenergic response, but &bgr;-blockers should be used with great caution, if at all, and treatment directed against mast cell mediators may be required.

The hemodynamic and neurohumoral phenotype of postural tachycardia syndrome

Background: Previous studies of patients with postural tachycardia syndrome (POTS) have been hampered by relatively small cohorts, failure to control medications and diet, and inconsistent testing procedures. Methods: The Vanderbilt Autonomic Dysfunction Center Database provided results of posture studies performed in 165 patients and 66 normal controls after dietary and medication restrictions. All posture studies were performed after an overnight fast and ≥30 minutes of supine rest. Results: In both the supine and standing positions, heart rate (HR) and plasma concentrations of norepinephrine (NE), epinephrine, and dopamine were higher in patients with POTS compared with the healthy controls. Supine diastolic blood pressure (BP) was also elevated in POTS, whereas supine plasma l-3,4-dihydroxyphenyalanine was reduced. In an analysis of patient subgroups with either an upright plasma NE ≥ 3.54 nM (high NE) or an upright plasma NE < 3.54 nM (normal NE), HR and BP were greater in the patient subgroup with high NE. In addition to these significant differences in hemodynamic and catechol measurements, we demonstrated that supine and standing plasma aldosterone and the aldosterone/renin ratio were decreased in patients with POTS. Plasma renin activity (PRA) tended to be higher in patients, and standing HR for those in the highest PRA quartile was significantly greater than for those in the lowest PRA quartile. Conclusions: Our results from larger cohorts of patients and controls than previously studied confirm published findings and contribute additional evidence of sympathetic activation in postural tachycardia syndrome (POTS). Abnormalities in the renin–angiotensin–aldosterone system may also contribute to the POTS phenotype.

ResearchMatch: a national registry to recruit volunteers for clinical research.

The authors designed ResearchMatch, a disease-neutral, Web-based recruitment registry to help match individuals who wish to participate in clinical research studies with researchers actively searching for volunteers throughout the United States. In this article, they describe ResearchMatchs stakeholders, workflow model, technical infrastructure, and, for the registrys first 19 months of operation, utilization metrics. Having launched volunteer registration tools in November 2009 and researcher registration tools in March 2010, ResearchMatch had, as of June 2011, registered 15,871 volunteer participants from all 50 states. The registry was created as a collaborative project for institutions in the Clinical and Translational Science Awards (CTSA) consortium. Also as of June 2011, a total of 751 researchers from 61 participating CTSA institutions had registered to use the tool to recruit participants into 540 active studies and trials. ResearchMatch has proven successful in connecting volunteers with researchers, and the authors are currently evaluating regulatory and workflow options to open access to researchers at non-CTSA institutions.

The effect of sildenafil on nitric oxide–mediated vasodilation in healthy men

Sildenafil, a treatment for erectile dysfunction, is a specific phosphodiesterase type 5 (PDE 5) inhibitor that enhances nitric oxide (NO)–mediated vasodilation in the corpus cavernosum by inhibiting cyclic guanosine monophosphate breakdown. Since PDE 5 is widely expressed in the vasculature, we examined the hypothesis that sildenafil could enhance NO‐mediated vasodilation in other vascular beds and improve endothelial function.