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At least 685 records · Page 38Linked to original sources
PubMed1996

Effects of hand-used on unilateral spatial neglect: a case study.

It was originally claimed that left hand use on line bisection tasks reduced the extent of left neglect by Halligan and Marshall. However, in a following study, the same research group failed to reproduce this left hand amelioration effect if the left hand was initially placed on the right side, and they claimed that spatio-motor cueing was more important in reducing unilateral neglect than the hand used. The present study concerns with the validity of these two theoretical views on modification of unilateral neglect, i.e., hemispheric activation and spatio-motor cueing. A patient with left unilateral neglect and a slight left hemiparesis participated in three experiments. Under conventional testing condition, line bisection performed with the right hand showed more severe left neglect than when performed with the left hand. These hand effects were modified by changing a starting position of the patient's hand when bisecting horizontal lines. However, under body-fixed condition, effects in hand-used as well as starting position were again significant. The results suggest that not only spatio-motor cueing but also differential hemispheric activation can exert a profound effect on unilateral neglect.

Aged↗
PubMed1989

Influence of retention time on degradation of pancreatic enzymes by human colonic bacteria grown in a 3-stage continuous culture system.

Hydrolytic enzymes were measured in gut contents from four sudden death victims. Pancreatic amylase and total protease activities decreased distally from the small bowel to the sigmoid/rectum region of the large intestine, showing that considerable breakdown or inactivation of the enzymes occurred during gut transit. To determine whether pancreatic enzymes were substrates for the gut microflora, mixed populations of bacteria were grown in a 3-stage continuous culture system on a medium that contained pancreatic extract as the sole nitrogen source. The multichamber system (MCS) was designed to reproduce in vitro, the low pH, high nutrient, fast growth conditions of the caecum and right colon and the neutral pH, low nutrient, slow growth conditions of the left colon. Results showed that pancreatic amylase was resistant to breakdown by intestinal bacteria compared with the peptide hydrolases in pancreatic secretions. Leucine aminopeptidase, trypsin and to a lesser degree, chymotrypsin, were easily degraded by gut bacteria, but pancreatic elastase was comparatively resistant to breakdown. Protein degradation in the MCS, as determined by enzyme activities, protein concentration and ammonia and phenol production, increased concomitantly with system retention time over the range 24-69 h. These results suggest that intestinal bacteria play an important role in the breakdown of hydrolytic enzymes secreted by the pancreas and that this process and protein fermentation in general, is likely to occur maximally in individuals with extended colonic retention times.

Amylases↗
PubMed1988

Radiological changes in rheumatoid arthritis: measurement of area of juxta-articular bone as outcome event in clinical therapeutic trials of antirheumatic drugs.

A high degree of intra - and inter - rater reproducibility was obtained in measurement of a standardized area of the head of the first right metacarpal using a precision digitizer. This instrument had an accuracy for every point digitized of 0.127 mm. Intra-rater difference between readings at approximately a month's interval showed no significant differences. The method is reasonably simple to perform and is applicable to small joints such as the proximal interphalangeal joints. The method may prove useful in following progression of joint damage in rheumatoid arthritis.

Anti-Inflammatory Agents↗
PubMedDate not supplied

Animal models for intra-abdominal infection.

Animal models are widely used to study intra-abdominal infections. Experimental intra-abdominal infections. Experimental intra-abdominal infection is a bi-phasic process; initially a peritonitis or septic phace caused by E. coli and later a chronic-abscess forming stage, caused by B. fragilis similar to human beings. Various methods have been described. These methods includes challenge of the peritoneum with either endogenous bacteria or inoculation of pure bacteria or fectal material. Non-bacterial models have also been described. Each of these models have their own advantages and disadvantages. The aim and the end points should govern the selection of the right model to be used for experimental purposes. The ideal model should be reliable, standard, reproducible and resembling human disease. A single model with those specifications is yet to be described.

Abdomen↗
PubMed1999

Automatic and efficient R wave discrimination in the right atrium using a two-state hidden Markov model.

INTRODUCTION: Discrimination of far-field R waves from atrial events in atrial electrograms (EGMs) is problematic in present implantable pacing systems. Adjustments of atrial refractory periods and sensitivity settings are the only options, and they will not provide optimal performance in many patients. The reliable detection or rejection of R waves in atrial EGMs would avoid problems of atrial undersensing or oversensing, thus benefiting DDD patients by providing more reliable and specific atrial arrhythmia detection. In addition, detection of far-field R waves could allow a measurement of AV conduction time in AAI and aid in discrimination of supraventricular tachyarrhythmia from ventricular tachyarrhythmia. METHODS AND RESULTS: Both atrial and ventricular unipolar EGMs were collected from 25 patients undergoing pacemaker implant or replacement. An average of 141 seconds of intrinsic or VVI paced EGMs was recorded and post analyzed. A new two-state hidden Markov model (HMM) was developed specifically for far-field R wave and P wave discrimination in the atrium. The recorded patients' EGMs were analyzed using this model, and the sensitivity and positive predictivity of far-field R wave detection were evaluated. The collected atrial EGMs were visually examined and marked as the control for verification of the detection analysis. Far-field R wave detection using this model had an overall sensitivity of 94% +/- 9.4% and a positive predictivity of 98.3% +/- 4.4%; and the far-field R wave rejection using the same model had a sensitivity and a positive predictivity of 98.8% +/- 3.8% and 99.1% +/- 1.7%, respectively. CONCLUSION: Far-field R wave detection in the right atrium by the two-state HMM is reliable and accurate, and can significantly improve atrial arrhythmia management for patients.

Adolescent↗
PubMed1991

Three echocardiographic methods in right ventricular function evaluation.

We employed two-dimensional echocardiography for the assessment of right ventricular (RV) volumes and/or function in a series of 44 patients. The results of three different echocardiographic approaches were compared with the data obtained from single-plane RV angiography following ultrasound within a 7-day interval. Only the echocardiographic area length method with two orthogonal imaging planes employed (apical 4-chamber and subcostal projections) yielded the beneficial results. The correlations between echocardiographic and angiographic RV volume estimates were rather high (end-diastolic volume: r = 0.83, end-systolic volume: r = 0.82, stroke volume: r = 0.81) and satisfactory in ejection fraction (r = 0.75). Using the method mentioned, the differentiation of patients with an angiographic evidence of RV failure (echocardiographic ejection fraction less than 0.55) from those without it was possible with a sensitivity of 0.68 and a specificity of 0.82. Concerning the clinical impact of the presented study, we can recommend the technique in question as a screening procedure for the detection of changes in RV function exceeding 12% (95% confidence limits).

Cineangiography↗
PubMed2006

Feasibility and accuracy of a routine echocardiographic assessment of right ventricular function.

The evaluation of right ventricular (RV) systolic function is important for its clinical and prognostic value but difficult to obtain due to RV complex anatomy. Aims of this study were to evaluate the feasibility of a routine use of RV fractional shortening area (FSA), systolic excursion (TAPSE) and peak systolic velocity (PSV) of tricuspidal annular motion in a large series of cases (900 pts), to determine the values in normal subjects (150) and in patients (750) with different pathologies and to correlate these indexes to clinical and echo-Doppler variables. FSA (50.3+/-10% vs 54.6+/-9% p<0.01), TAPSE (20.2+/-5 vs 24.7+/-4 mm, p<0.01) and PSV (16.2+/-4 vs 20+/-4 cm/s, p<0.01) were lower in patients than in normals, correlated positively to left ventricular ejection fraction and negatively to the pulmonary pressure. The values of 17 mm for TAPSE, 12 cm/s for PSV and 37% for FSA identified patients with high specificity. The values in subgroups of pathological patients were evaluated and compared.

Echocardiography, Doppler↗
PubMedDate not supplied

Observer variability in the evaluation of dual-isotope Tl-201/Tc-99m sestamibi rest/stress myocardial perfusion SPECT in men and women with known or suspected stable angina pectoris.

BACKGROUND: Observer variability of dual-isotope myocardial perfusion imaging (MPI) with single photon emission computed tomography has rarely been investigated. The aim of our study was to evaluate the interpretive reproducibility with this technique. METHODS AND RESULTS: We report on 507 patients with known or suspected stable angina who were studied before coronary angiography. A 1-day thallium 201/technetium 99m sestamibi rest/stress MPI protocol was used. MPI was interpreted by 2 independent observers without knowledge of clinical data, using a 20-segment scoring model. By consensus, the overall rate of abnormal MPI was 49% (59% in men and 34% in women). The interobserver agreement for the whole group (kappa = 0.85) and for men and women separately (kappa = 0.86 and 0.82, respectively) was excellent with regard to the overall diagnosis (normal, reversible, or fixed defects) as well as left anterior descending and left circumflex artery vascular territories (kappa = 0.85 and 0.82, respectively). However, in the right coronary artery territory, agreement was excellent in men (kappa = 0.83) but moderate in women (kappa = 0.57). CONCLUSIONS: In a relatively large group of men and women with stable angina pectoris, interpretive reproducibility (overall and individual vessel diagnosis) was excellent, except in the right coronary artery territory of women, in which it was moderate.

Angina Pectoris↗
PubMed1992

In vitro validation of a thermodilution right ventricular ejection fraction method.

A thermodilution catheter and computer system has been developed to measure right ventricular ejection fraction and volumes. To evaluate the performance of this method, the thermodilution system was evaluated in an in vitro pulsatile flow model. Thermodilution measurements of ejection fraction (EF), cardiac output (CO), stroke volume (SV), end-diastolic volume (EDV), and end-systolic volume (ESV) were compared with known values in a pulsatile flow bench. Thermodilution EF measurements correlated very well with the pulsatile flow model (r2 = 0.95, m [slope] = 0.85, SEE = 4.0 EFU). Thermodilution CO and SV were highly predictive of actual pulsatile flow (r2 = 0.99, m = 0.99, SEE = 187 ml/min and r2 = 0.98, m = 0.96, SEE = 2.5 ml, respectively). Thermodilution end-diastolic and end-systolic volume measurements resulted in low mean eror, -1.8% and 0.6%, respectively. The standard deviations of the error for EDV and ESV were 11.0% and 16.4%. The thermodilution measurements were repeatable, with CO, SV, and EF coefficients of variation of 3.2%, 3.3%, and 4.7%, respectively. EDV and ESV were slightly more variable, with coefficients of variation of 5.5% and 7.2%, respectively.

Cardiac Catheterization↗
PubMedDate not supplied

Doppler estimation of changes in pulmonary artery pressure during hypoxic breathing.

To assess the use of Doppler echocardiographic screening for abnormal pulmonary vasoreactivity, we measured pulmonary artery pressure in 10 adult patients and 11 normal subjects while recording Doppler right ventricular outflow acceleration time, pre-ejection period, and ejection time. In the normal subjects we also measured the changes in each parameter after 10 minutes of hypoxic breathing (FIO2 = 0.12). Mean pulmonary artery pressure increased by 39% during hypoxia (13 +/- 4.3 to 18 +/- 5.4 mm Hg). In the patients and normal subjects at rest, mean pulmonary artery-pressure correlated well with acceleration time (r = -0.84; standard error of the estimate, 6.6 mm Hg; p = 0.0001). Over the narrow range of mean pulmonary artery pressure in normal subjects at rest, mean pulmonary artery pressure did not correlate well with acceleration time, acceleration time/pre-ejection period, or acceleration time/right ventricular ejection time. However, changes in mean pulmonary artery pressure induced by hypoxic breathing did correlate with changes in acceleration time/right ventricular ejection time (r = 0.73; standard error of the estimate, 2.3 mm Hg; p = 0.01). Doppler ultrasound may offer a noninvasive means for detecting abnormal pulmonary vasoreactivity in asymptomatic individuals at risk for developing pulmonary hypertension.

Adult↗
PubMed1988

[Reproducibility and development of pulse wave velocity at rest and during exertion].

PURPOSE: to search in which situation the PWV is the most reproducible. METHODOLOGY: PWV is measured with a continuous doppler technique along the subclavial radial arterial segment on the right forearm. 30 normotensive subjects (20-30 years) are studied twice running at 24-hour interval at rest and during stress (ergometric bicycle, stress levels: 50, 75, 100 watts/mn). STATISTICS: Student test and correlation when the data are normally distributed. RESULTS: mean PWV increases progressively with blood pressure during stress. REST: 10.0, 50W: 11.3, 75W: 12.33, 100W: 13.32, 4 mn rest: 10.6. Mean differences (MD) with standard deviations (SD) and correlation (COR) are as following: (Table: see text). If we take into consideration MD, SD and COR between the 2 stress tests, 75W level appears to be the most reproducible. CONCLUSION: these data must be taken into account when using PWV to appreciate the vascular effect of some medications especially in hypertension.

Adult↗
PubMed1984

Gated first pass radionuclide ventriculography. Methods, validation, and applications.

Electrocardiographic gating provides an alternative method of acquiring first pass radionuclide ventriculograms from both ventricles. This report details the methods of acquisition and analysis, provides validation and reproducibility data, and describes applications of gated first pass radionuclide ventriculography using a count-based method. Left ventricular ejection fractions measured by gated first pass were correlated quite closely with gated blood pool ventriculography (n = 43; r = 0.95) but less well with contrast angiography (n = 23; r = 0.72). The right ventricular ejection fractions measured by gated first pass compared favorably with gated blood pool ventriculography (n = 32; r = 0.93). When one observer processed the images two times, the reproducibilities of RVEF (n = 10; r = 0.99) and LVEF (n = 10; r = 0.88) were excellent. Similarly, when two observers processed the images independently, the reproducibilities of RVEF (n = 11; r = 0.99) and LVEF (n = 11; r = 0.98) were excellent. The first pass studies were obtained in a right anterior obliquity, which provided the best atrioventricular chamber separation and provided a different view of global ventricular function and segmental wall motion from that provided by the standard blood pool views.

Adolescent↗
PubMed1976

Human ventricular refractoriness. Effects of cycle length, pacing site and atropine.

The effective refractory period of the right ventricle (ERP-V) was measured in 27 patients during atrial or ventricular pacing using the ventricular extra stimulus method. Pacing was conducted with impulses of 1.5-2 times diastolic threshold. The ERP-V was directly related to the basic cycle length (BCL) although the ERP-V was always greater for atrial pacing than for ventricular pacing at a given BCL. The ratio ERP-V/BCL was greater at shorter cycle lengths indicating that a larger fraction of the cycle was refractory at faster heart rates. The ratio ERP-V/QT interval did not change over a range of BCLs, but the ratio was larger for atrial pacing (.77 +/- .05 SD) than for ventricular pacing (.60 +/- .05). Atropine (1 mg i.v.) was given to six patients. The drug did not affect the ERP-V in six of eleven determinations, prolonged ERP-V twice and shortened it slightly three times. Measurements were reproducible over an hour but varied at a given BCL when measured on separate days. Asymptomatic repetitive beating occurred in seven of 27 patients when the premature stimulus was within 20 msec of the ERP-V. The effective refractory period of the right ventricle in man can be determined reproducibly and with safety. Changes induced by various perturbations parallel results from in vitro single cell and myocardial studies.

Adult↗
PubMed1984

Identification of reproducible ventricular tachycardia in a canine model.

Epicardial mapping was used as a standard to investigate how well the limb leads, both alone and in conjunction with 5 select epicardial electrodes, can verify reproducibility in a common, open-chest canine model of ventricular tachycardia (VT). Reproducible VT was defined as 2 or more episodes of monomorphic VT with similar rates, limb lead tracings and epicardial maps. In this study, 21 dogs underwent 2-hour occlusion of the left anterior descending coronary artery followed by reperfusion. Three days later, programmed stimulation was used to induce VT that was analyzed with limb leads I, II and III and 27 simultaneously recorded, bipolar epicardial electrodes. Thirteen dogs had VT of which 11 had polymorphic VT (varying QRS morphology). Twelve dogs yielded at least 1 form of monomorphic VT. Eight had 2 or more distinct forms of monomorphic VT (pleomorphism). Four of these 8 dogs had pleomorphic VT that was not apparent from the limb lead tracings, but was recognized from the epicardial activation maps constructed from the 27 epicardial recordings. To provide a method of distinguishing various VTs without the need of full epicardial mapping, 5 of the 27 epicardial electrodes were selected. These were positioned over the midanterior and midposterior right and left ventricles, and the left ventricular apex. By analyzing electrogram morphology and activation time, VT reproducibility could be as accurately identified with these 5 electrodes as with epicardial mapping derived from 27 electrodes. In conclusion, multiple VT morphologies are common in this open-chest canine model. Limb lead recordings alone are inadequate for analysis of VT reproducibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Reproducibility of the ventricular synchronization parameters assessed by multiharmonic phase analysis of radionuclide angiography in the normal heart.

Radionuclide angiography (RNA) permits analysis of contractility and conduction abnormalities. We determined the parameters of normal ventricular synchronization, assessed the reproducibility of the technique, and compared first harmonic (1H) and third harmonic (3H) analysis. Forty-four normal subjects (28 men and 16 women) were studied. RNA was performed in left anterior oblique (LAO) and left lateral (LL) projections. The onset (To), mean time (Tm), total contraction time (Tt) for right ventricle (RV) and left ventricle (LV), interventricular time (T(RV-LV) = Tm(LV - Tm(RV)) in LAO, and the apex-to-base time (T(a-b)) in LL were measured on the histograms of the time-activity curve. Reproducibility (R) was tested by studying 26 consecutive patients with two successive RNAs. RV starts contracting 25 ms before LV (To(RV) = 29 +/- 37 ms; To(LV) = 54 +/- 39 ms; mean +/- SD) with a 37 ms longer total contraction time. T(RV-LV) is 3 +/- 16 ms. In LL projection, apex and base contract synchronously: T(a-b) = 2 +/- 16 ms. 3H analysis enlarges all duration parameters (To, Tm and Tt), but does not alter synchronization (deltaT(a-b) and deltaT(RV-LV) between 1H and 3H <1%, p = NS). Reproducibility of the duration (T(tLV) and T(tRv)) and synchronization parameters (T(a-b) and T(RV-LV)) is high (R < or = 2.2%). In conclusion, the simultaneous contraction of right and left ventricles and of apex and base can be quantified by RNA phase analysis with high reproducibility. These results, consistent with published electrophysiological data, provide the basis for further non-invasive investigations of ventricular resynchronization in patients with basal electrical or mechanical asynchrony.

Female↗
PubMed2006

Echocardiographic right ventricular strain analysis in chronic heart failure.

OBJECTIVE: We sought to compare the additive value of right ventricular (RV) function assessed by longitudinal systolic strain (epsilon% - ROI: 9.2 at 10.8 mm) with cardiopulmonary exercise testing (CPET) or brain natriuretic peptide (BNP) in patients with heart failure (HF). METHOD: We studied 19-patients (age = 56 +/- 8 years) in New York Heart Association HF class III-IV, who underwent standard and tissue Doppler echocardiography, CPET and BNP measurements on the same day. RV function was assessed by systolic strain (epsilon, %, ROI: 9.2-10.8 mm) in the mid-segment. Clinical outcomes were examined at 6 months. RESULTS: epsilon (-19.9+/-6.8%) was correlated with BNP (R = 0.52, P = 0.02), slope VE/VCO(2) (R = -0.65, P = 0.003), peak VO(2) (R = 0.46, P = 0.04) and the maximal workload (Watts) developed during CPET (R = 0.54, P=0.02). During follow-up, 1-patient died, 1-underwent heart transplantation, and 4 were re-hospitalized for worsening HF. Patients with major adverse cardiac events (MACE) had a significantly higher mean BNP concentration (852.8 ng/mL +/- 1114.3 vs. 201.4+ /- 293.8, P = 0.03), higher VE/VCO(2) (41.3 +/- 3.6 vs. 35.0 +/- 4.8 P < 0.001) and lower epsilon (-13.9 +/- 4.9 vs. -22.2+ /- 5.8, P < 0.001) than patients who remained MACE-free. By multivariate analysis, ST was the only predictor of MACE. CONCLUSION: In HF-patients presenting, RV-function assessed by systolic epsilon was reliable, easily measurable and a stronger prognosticator than CPET or BNP.

Chronic Disease↗
PubMed1998

Real-time three-dimensional echocardiography for determining right ventricular stroke volume in an animal model of chronic right ventricular volume overload.

BACKGROUND: The lack of a suitable noninvasive method for assessing right ventricular (RV) volume and function has been a major deficiency of two-dimensional (2D) echocardiography. The aim of our animal study was to test a new real-time three-dimensional (3D) echo imaging system for evaluating RV stroke volumes. METHODS AND RESULTS: Three to 6 months before hemodynamic and 3D ultrasonic study, the pulmonary valve was excised from 6 sheep (31 to 59 kg) to induce RV volume overload. At the subsequent session, a total of 14 different steady-state hemodynamic conditions were studied. Electromagnetic (EM) flow probes were used for obtaining aortic and pulmonic flows. A unique phased-array volumetric 3D imaging system developed at the Duke University Center for Emerging Cardiovascular Technology was used for ultrasonic imaging. Real-time volumetric images of the RV were digitally stored, and RV stroke volumes were determined by use of parallel slices of the 3D RV data set and subtraction of end-systolic cavity volumes from end-diastolic cavity volumes. Multiple regression analyses showed a good correlation and agreement between the EM-obtained RV stroke volumes (range, 16 to 42 mL/beat) and those obtained by the new real-time 3D method (r=0.80; mean difference, -2.7+/-6.4 mL/beat). CONCLUSIONS: The real-time 3D system provided good estimation of strictly quantified reference RV stroke volumes, suggesting an important application of this new 3D method.

Animals↗
PubMedDate not supplied

Right ventricular volume measurement using the conductance catheter method: validation in excised porcine hearts.

The conductance catheter method for measuring right ventricular (RV) volume changes was assessed in seven excised porcine hearts. A 5-FG conductance catheter was placed within a latex balloon and positioned in the RV cavity of seven freshly excised porcine hearts. Conductance was recorded while saline was withdrawn from the intraventricular balloon in 2 ml decrements. Linear regression analysis of measured conductance versus reference volumes was computed. The effect of left ventricular (LV) filling and catheter length on conductance derived RV volume was also determined. Conductance derived volumes were highly correlated with reference volumes [R2 0.976, standard deviation (SD) 0.035]. The mean gradient of regression was 0.97 (SD 0.10), and it was not significantly affected by LV volume alterations. However, when we analyzed LV filling, a small but significant increase in the y-intercept was observed (LV empty 3.11 ml, SD 1.71; LV full 4.58, SD 2.39; p = 0.008). Introduction of the catheter through either the tricuspid or pulmonary orifices were both effective in ventricular volume measurement. The effect of mismatch between the catheter length and the RV long axis dimension was evaluated by changing the position of the active sensing electrodes along the catheter body. Conductance measurements, obtained from catheters shorter than the long axis of the RV, still maintained a highly linear correlation with real volume, but regression gradients were significantly reduced (long 0.975, SD 0.087; medium 0.787, SD 0.094; small 0.589, SD 0.091; p < 0.001). These results show that a conductance catheter of appropriate length can accurately measure RV volume, despite the complex shape and geometric changes associated with ventricular filling.

Animals↗