Determinants of Pulmonary Hypertension in Left Ventricular Dysfunction

AbstractObjectives. This study sought to analyze the determinants of pulmonary hypertension in patients with left ventricular dysfunction.Background. Pulmonary hypertension in patients with left ventricular dysfunction is a predictor of poor outcome. The independent role of cardiac functional abnormalities in the genesis of pulmonary hypertension is unclear.Methods. In 102 consecutive patients with primary left ventricular dysfunction (ejection fraction <50%), systolic pulmonary artery pressure was prospectively measured by Doppler echocardiography (using tricuspid regurgitant velocity), and left ventricular systolic and diastolic function, functional mitral regurgitation, cardiac output and left atrial volume were quantified.Results. Systolic pulmonary artery pressure was elevated in patients with left ventricular dysfunction (51 ± 14 mm Hg [mean ± SD]), but the range was wide (23 to 87 mm Hg). Of the numerous variables correlating significantly with systolic pulmonary artery pressure, the strongest were mitral deceleration time (r = −0.61, p = 0.0001; odds ratio of pulmonary pressure ≥50 mm Hg [95% confidence interval] if <150 ms, 48.8 [14.8 to 161]) and mitral effective regurgitant orifice (r = 0.50, p = 0.0001; odds ratio [95% confidence interval] if ≥20 mm2, 5.9 [2.3 to 15.5]). In multivariate analysis, these two variables were the strongest predictors of systolic pulmonary artery pressure in association with age (p = 0.005). Ejection fraction or end-systolic volume was not an independent predictor of pulmonary artery pressure.Conclusions. Pulmonary hypertension is frequent and highly variable in patients with left ventricular dysfunction. It is not independently related to the degree of left ventricular systolic dysfunction but is strongly associated with diastolic dysfunction (shorter mitral deceleration time) and the degree of functional mitral regurgitation (larger effective regurgitant orifice). These results emphasize the importance of assessing diastolic function and quantifying mitral regurgitation in patients with left ventricular dysfunction.(J Am Coll Cardiol 1997;29:153–9)

Spatial normalization improves the quality of genotype calling for Affymetrix SNP 6.0 arrays

<p>Abstract</p> <p>Background</p> <p>Microarray measurements are susceptible to a variety of experimental artifacts, some of which give rise to systematic biases that are spatially dependent in a unique way on each chip. It is likely that such artifacts affect many SNP arrays, but the normalization methods used in currently available genotyping algorithms make no attempt at spatial bias correction. Here, we propose an effective single-chip spatial bias removal procedure for Affymetrix 6.0 SNP arrays or platforms with similar design features. This procedure deals with both extreme and subtle biases and is intended to be applied before standard genotype calling algorithms.</p> <p>Results</p> <p>Application of the spatial bias adjustments on HapMap samples resulted in higher genotype call rates with equal or even better accuracy for thousands of SNPs. Consequently the normalization procedure is expected to lead to more meaningful biological inferences and could be valuable for genome-wide SNP analysis.</p> <p>Conclusions</p> <p>Spatial normalization can potentially rescue thousands of SNPs in a genetic study at the small cost of computational time. The approach is implemented in R and available from the authors upon request.</p

A single case study of a family-centred intervention with a young girl with cerebral palsy who is a multimodal communicator

Background - This paper describes the impact of a family-centred intervention that used video to enhance communication in a young girl with cerebral palsy. This single case study describes how the video-based intervention worked in the context of multimodal communication, which included high-tech augmentative and alternative communication (AAC) device use. This paper includes the family's perspective of the video intervention and they describe the impact of it on their family. Methods - This single case study was based on the premise that the video interaction guidance intervention would increase attentiveness between participants during communication. It tests a hypothesis that eye gaze is a fundamental prerequisite for all communicative initiatives, regardless of modality in the child. Multimodality is described as the range of communicative behaviours used by the child and these are coded as AAC communication, vocalizations (intelligible and unintelligible), sign communication, nodding and pointing. Change was analysed over time with multiple testing both pre and post intervention. Data were analysed within INTERACT, a computer software to analyse behaviourally observed data. Behaviours were analysed for frequency and duration, contingency and co-occurrence. Results - Results indicated increased duration of mother's and girl's eye gaze, increased frequency and duration in AAC communication by the girl and significant change in frequency [χ2 (5, n = 1) = 13.25, P < 0.05] and duration [χ2 (5, n = 1) = 12.57, P < 0.05] of the girl's multimodal communicative behaviours. Contingency and co-occurrence analysis indicated that mother's eye gaze followed by AAC communication was the most prominent change between the pre- and post-intervention assessments. Conclusions - There was a trend for increased eye gaze in both mum and girl and AAC communication in the girl following the video intervention. The family's perspective concurs with the results

Amplitude-weighted mean velocity: Clinical utilization for quantitation of mitral regurgitation

AbstractObjectives. The purpose of this study was to determine the clinical usefulness of the amplitude-weighted mean velocity method for quantitation of mitral regurgitation.Background. Amplitude-weighted mean velocity is a nonvolumetric method for calculating the mitral regurgitant fraction. Its previous validation at one center mandated an independent assessment of its usefulness and limitations.Methods. In 56 patients with and 16 patients without mitral regugitation, the regurgitant fraction was measured simultaneously by amplitude-weighted mean velocity, quantitative Doppler study and quantitative two-dimensional echocardiography. In 16 patients, multiple gain settings were used to determine the influence of this variable on amplitude-weighted mean velocity.Results. In ptients without regurgitation, amplitude-weighted mean velocity showed more scattering of regurgitant fraction (−18% to 23%) than Doppler (p = 0.016) or two-dimensional echocardiography (p = 0.022). The absolute value of regurgitant fraction was (mean ± SD) 8 ± 6%, 4 ± 2% and 4 ± 3%, respectively (p = NS). With increasing gain, the amplitudeweighted mean velocity mitral and aortic integrals increased, but the calculated regurgitant fraction remained unchanged. In patients with mitral regurgitation, significant correlation was found between amplitude-weighted mean velocity and Doppler study (r = 0.79, p = 0.0001) and between implitude-weighted mean velocity and two-dimensional echocardiography (r = 0.76, p = 0.0001) for calculated regurgitant fraction, but the standard error of the estimate (12%) was large.Conclusions. The amplitude-weighted mean velocitycalculated regurgitant fraction is gain independent, whereas the aortic and mitral integrals are gain dependent. Compared with Doppler and two-dimensional echocardiography, It shows more scattering of values in patients without regurgitation, but the methods correlate significantly in patients with mitral regurgitation. Amplitude-weighted mean velocity can be used as a simple adjunctive tool for comprehensive, noninvasive quantitation of mitral regurgitation

Prequtaneous transluminal angioplasty in patients with multivessel coronary disease: How important is complete revascularization for cardiac event-free survival?

AbstractThe relative influences of revascularizationstaus and baseline characteristics on long-term outcome were examined in 867 patients with multivessel coronarydisease who had undergone successful coronary angioplasty. These patients represented 83% of a total of 1,039 patients in whom angioplasty had been attempted with an in-hospltal mortality and infarction rate of 2.5% and 48%, respectively. Emergency coronary bypass surgery was needed in 4.9%. Of the 867 patients, 41% (group 1) were considered to have complete revascularization and 59% (group 2) to have incomplete revascularization. Univariate analysis revealed major differences between these two groups with patients in group 2 characterized by advanced age, more severe angina, a greater likelihood of previous coronary surgery and infarction, more extensive disease and poorer left ventricular function.Over a mean follow-up period of 26 months, the probability of event-free survival was significantly lower for group 2 only with respect to the need for coronary artery surgery (p = 0.004) and occurrence of severe angina (p = 0.04). The difference in modality was of borderline significance (p = 0.051) and there were no signiicant difference between 1 and 2 in either the incidence of myocardial infarction or the need for repeat angioplasty.Muitivariate analysis identified independent baseline predictors of late cardiac events that were then used to adjust the probabilities of event-free survival. This adjustment effectively removed any significant influence of completeness of revascuiarization on event-free survival for any of the above end points including the combination of death, myocardial infarction and need for coronary artery surgery. Therefore, late outcome in these patients is not significantly influenced by revascularization status but depends more on baseline patient characteristics

Revised astrometric calibration of the Gemini Planet Imager

We present a revision to the astrometric calibration of the Gemini Planet Imager (GPI), an instrument designed to achieve the high contrast at small angular separations necessary to image substellar and planetary-mass companions around nearby, young stars. We identified several issues with the GPI data reduction pipeline (DRP) that significantly affected the determination of the angle of north in reduced GPI images. As well as introducing a small error in position angle measurements for targets observed at small zenith distances, this error led to a significant error in the previous astrometric calibration that has affected all subsequent astrometric measurements. We present a detailed description of these issues and how they were corrected. We reduced GPI observations of calibration binaries taken periodically since the instrument was commissioned in 2014 using an updated version of the DRP. These measurements were compared to observations obtained with the NIRC2 instrument on Keck II, an instrument with an excellent astrometric calibration, allowing us to derive an updated plate scale and north offset angle for GPI. This revised astrometric calibration should be used to calibrate all measurements obtained with GPI for the purposes of precision astrometry