Jack H. Boyd

Web credibility research: a method for online experiments and early study results

Through iterative design and testing, we developed a procedure for conducting online experiments. Using this research method, we conducted two recent studies on Web credibility. The data from the first study suggest that Web banner ads reduce the perceived credibility of a Web pages content. The data from the second study show that attribution elements--in this case, author photographs--can also affect the credibility of Web content. This research method and our early results have implications for both HCI researchers and Web site designers.

Cavopulmonary assist: circulatory support for the univentricular fontan circulation

BACKGROUND Following Fontan palliation, the univentricular circulation is notable for coexisting systemic venous hypertension and pulmonary arterial hypotension. Assisted cavopulmonary blood flow to overcome this pressure gradient would restore the circulation to one more closely resembling normal two-ventricle physiology. We hypothesized that mechanical augmentation of cavopulmonary blood flow would provide physiologic stability in a model of cavopulmonary diversion and univentricular circulation. METHODS Yearling sheep (n = 13, mean weight 56.5 kg) underwent total cavopulmonary diversion on cardiopulmonary bypass. The superior and inferior vena cavae were anastomosed directly to the right pulmonary artery. Axial flow pumps were positioned within both vena cavae to assist blood flow from the systemic venous circulation into the pulmonary vasculature. Baseline ventilation was resumed, cardiopulmonary bypass was weaned, and pump support was titrated to obtain normal physiologic measurement. Cardiopulmonary data were collected for 6 hours. RESULTS All animals demonstrated hemodynamic stability without need for volume loading, inotropic support, or pulmonary vasodilator therapy. Cardiac output, pulmonary vascular resistance, pulmonary arterial pressure, inferior vena caval pressure, and arterial pCO(2) and pO(2) values 6 hours after intervention were similar to baseline values. Arterial lactate levels steadily decreased throughout the cavopulmonary assist period. CONCLUSIONS Cavopulmonary assist with a percutaneous pump provides physiologic stability in a model of total cavopulmonary diversion and univentricular Fontan circulation without altering regional volume distribution or cardiac output. This mode of circulatory support may have potential to benefit patients with marginal Fontan hemodynamics in both the early and late time periods.

Methodological Standards for Meta-Analyses and Qualitative Systematic Reviews of Cardiac Prevention and Treatment Studies: A Scientific Statement From the American Heart Association

Meta-analyses are becoming increasingly popular, especially in the fields of cardiovascular disease prevention and treatment. They are often considered to be a reliable source of evidence for making healthcare decisions. Unfortunately, problems among meta-analyses such as the misapplication and misinterpretation of statistical methods and tests are long-standing and widespread. The purposes of this statement are to review key steps in the development of a meta-analysis and to provide recommendations that will be useful for carrying out meta-analyses and for readers and journal editors, who must interpret the findings and gauge methodological quality. To make the statement practical and accessible, detailed descriptions of statistical methods have been omitted. Based on a survey of cardiovascular meta-analyses, published literature on methodology, expert consultation, and consensus among the writing group, key recommendations are provided. Recommendations reinforce several current practices, including protocol registration; comprehensive search strategies; methods for data extraction and abstraction; methods for identifying, measuring, and dealing with heterogeneity; and statistical methods for pooling results. Other practices should be discontinued, including the use of levels of evidence and evidence hierarchies to gauge the value and impact of different study designs (including meta-analyses) and the use of structured tools to assess the quality of studies to be included in a meta-analysis. We also recommend choosing a pooling model for conventional meta-analyses (fixed effect or random effects) on the basis of clinical and methodological similarities among studies to be included, rather than the results of a test for statistical heterogeneity.

Surgical Unroofing of Hemodynamically Significant Left Anterior Descending Myocardial Bridges

BACKGROUND Left anterior descending artery myocardial bridges (MBs) range from clinically insignificant incidental angiographic findings to a potential cause of sudden cardiac death. Within this spectrum, a group of patients with isolated, symptomatic, and hemodynamically significant MBs despite maximally tolerated medical therapy exist for whom the optimal treatment is controversial. We evaluated supraarterial myotomy, or surgical unroofing, of the left anterior descending MBs as an isolated procedure in these patients. METHODS In 50 adult patients, we prospectively evaluated baseline clinical characteristics, risk factors, and medications for coronary artery disease, relevant diagnostic data (stress echocardiography, computed tomography angiography, stress coronary angiogram with dobutamine challenge for measurement of diastolic fractional flow reserve, and intravascular ultrasonography), and anginal symptoms using the Seattle Angina Questionnaire. These patients then underwent surgical unroofing of their left anterior descending artery MBs followed by readministration of the Seattle Angina Questionnaire at 6.6-month (range, 2 to 13) follow-up after surgery. RESULTS Dramatic improvements were noted in physical limitation due to angina (52.0 versus 87.1, p < 0.001), anginal stability (29.6 versus 66.4, p < 0.001), anginal frequency (52.1 versus 84.7, p < 0.001), treatment satisfaction (76.1 versus 93.9, p < 0.001), and quality of life (25.0 versus 78.9, p < 0.001), all five dimensions of the Seattle Angina Questionnaire. There were no major complications or deaths. CONCLUSIONS Surgical unroofing of carefully selected patients with MBs can be performed safely as an independent procedure with significant improvement in symptoms postoperatively. It is the optimal treatment for isolated, symptomatic, and hemodynamically significant MBs resistant to maximally tolerated medical therapy.

Transcatheter Aortic Valve Replacement Versus Aortic Valve Bypass: A Comparison of Outcomes and Economics.

BACKGROUND Transcatheter aortic valve replacement (TAVR) is currently offered to patients who are high-risk candidates for conventional surgical aortic valve replacement. For the past 37 years, off-pump aortic valve bypass (AVB) has been used in elderly patients at our center for this similarly high-risk group. Although TAVR and AVB were offered to similar patients at our center, comparisons of clinical outcomes and hospital economics for each strategy were not reported. METHODS We reviewed the clinical and financial records of 53 consecutive AVB procedures performed since 2008 with the records of 51 consecutive TAVR procedures performed since 2012. Data included demographics, hemodynamics, The Society of Thoracic Surgeons (STS) risk score, extent of coronary disease, and ventricular function. Follow-up was 100% in both groups. Hospital financial information for both cohorts was obtained. Mean risk score for the TAVR group was 10.1% versus 17.6% for AVB group (p < 0.001). RESULTS Kaplan-Meier hospital rates of 3- and 6-month survival and of 1-year survival were 88%, 86%, 81%, and 61% and 89%, 83%, 83%, and 70% for the TAVR and AVB groups, respectively (p = 0.781). Two patients who had undergone TAVR had a procedure-related stroke. The one stroke in an AVB recipient was late and not procedure related. At discharge, mild and moderate perivalvular and central aortic insufficiency were present in 31% and 16% of TAVR recipients, respectively; no AVB valve leaked. Transvalvular gradients were reduced to less than 10 mm Hg in both groups. The average hospital length of stay for the AVB-treated patients was 13 days, and it was 9 days for the TAVR-treated patients. Median hospital charges were

Surgical unroofing of hemodynamically significant myocardial bridges in a pediatric population

253,000 for TAVR and

Human aortic allograft: an excellent conduit choice for superior vena cava reconstruction

158,000 for AVB. Mean payment to the hospital was

Second Arterial Versus Venous Conduits for Multivessel Coronary Artery Bypass Surgery in California

65,000 (TAVR) versus

Bilateral Giant Coronary Artery Aneurysms Complicated by Acute Coronary Syndrome and Cardiogenic Shock

64,000 (AVB), and the mean positive contribution margin (profit) to the hospital was

The tip of the iceberg: Evaluating the mechanism behind dehiscence of mitral annuloplasty rings

14,000 for TAVR versus