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Results for “The Right to Reproduce”

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At least 379 records · Page 21Linked to original sources

PubMed2001

Continuous ambulatory monitoring of absolute right ventricular pressure and mixed venous oxygen saturation in patients with heart failure using an implantable haemodynamic monitor: results of a 1 year multicentre feasibility study.

BACKGROUND: Implantable sensors that monitor haemodynamics over time may be useful in patients with heart failure. This multicentre study assessed the feasibility of a system that has one sensor measuring absolute pressure and another measuring mixed venous oxygen saturation (SvO(2)). Both sensors were mounted on leads that were implanted in the right ventricle. METHODS: Twenty-one patients with heart failure (NYHA II-III) were included. Comparisons were made to right heart catheterizations at implant and at 2, 6 and 12 months thereafter. Patients underwent several haemodynamic provocations during the catheterizations. RESULTS: Overall, among functioning sensors, the IHM-1 values were highly correlated with reference values for all time points during all provocations, demonstrating high reproducibility and stability (r(2)=0.91, 0.79 and 0.78 for systolic, right ventricular diastolic and SvO(2), respectively). Although IHM-1 underestimated reference pressure values by 4.5 mmHg and SvO(2)by 1.6%, this difference was consistent across provocation and stable over 12 months of follow-up. Twelve of the 21 oxygen sensors failed to function and two pressure sensors had component failures. Preliminary analysis of long-term data revealed haemodynamic patterns that may be key indicators for therapeutic interventions. CONCLUSION: This multicentre feasibility study demonstrated the accuracy and stability of sensors implanted in the right ventricle. The IHM-1, using right ventricular pressures and SvO(2), with improved performance, might be useful in the study of pathophysiological mechanisms and treatment interventions in heart failure.

Adult↗

PubMed1994

[A new methodologic approach for determining right ventricular volumes from transesophageal echocardiography].

In order to develop a concept of right ventricular volume estimation accounting for variance in positioning of the transesophageal transducer, non-linear scale transformations of suitable measurements of areas and perimeters were used in a new modeling-approach. This type of modeling supposes self-similarity of ventricular dimensions, a mathematical concept generalizing the notion of proportionality. In a study using right ventricular casts, we were able to demonstrate the geometry of right ventricles complies with these assumptions. The resulting multivariate power law volume estimators were developed by non-linear data fitting by learning-analyses based upon angiographic reference volumes and two areas derived from non-orthogonal sections using a monoplane transducer in a first series of studies, and two orthogonal areas with corresponding perimeters using a biplane device in a second series. Correction factors for systolic and diastolic volumes were applied. By prospective test-analyses angiographic and TEE-derived volumes were compared to evaluate our volume estimator and good agreement was found. Trend was evaluated by correlation amounts to r = 0.95 (n = 22) in series 1 with monoplane transducer, and r = 0.9 (n = 20) in series 2 with biplane transducer. This approach is of use in monitoring right ventricular function in cases with unsuitable transthoracical windows, e.g., in cardiac surgery postoperatively.

Adult↗

PubMed2006

Stimulated release of calcitonin gene-related peptide from the human right atrium in patients with and without diabetes mellitus.

Calcitonin gene-related peptide (CGRP), a potent vasodilator released during activation from a subset of sensory Adelta- and C-fiber afferents, has been suggested to play a beneficial role in myocardial ischemia. Variations in CGRP release can possibly be correlated with diseases that involve changes in activity or degeneration of cardiac afferent fibers. The aim of the present study was to examine basal and stimulated CGRP release from cardiac tissue in patients who underwent cardiopulmonary bypass surgery and to compare patients with and without known history of diabetes mellitus. Small pieces of the right atrium routinely excised during the bypass operations were passed through series of oxygenated solutions. The TRPV1 receptor agonist capsaicin and the nitric oxide donor NONOate were added for stimulation of cardiac afferent fibers. The eluates were processed using an enzyme immuno-assay (EIA) for measurement of CGRP concentrations. Both capsaicin and NONOate caused significant increases in CGRP release. No significant differences in CGRP release between patients with and without diabetes mellitus were examined. The present study evaluates a simple and reproducible model for measuring stimulated CGRP release from the human right atrium.

Aged↗

PubMed2002

Spatial neglect in near and far space investigated by repetitive transcranial magnetic stimulation.

Localized repetitive transcranial magnetic stimulation was used to disrupt visuospatial perception in the near and far space of six healthy volunteer subjects. In addition to the baseline condition, they were stimulated over the right posterior parietal cortex, the right or left dorsal occipital cortex or the right ventral occipital cortex, during the brief presentation of a transected horizontal line. Subjects had to indicate whether the part of the line to the left or right of the transection appeared longer. The stimulus display was back-projected on a screen at a viewing distance of either 50 or 150 cm ("near" and "far" space, respectively). Reaction times and choices were measured. In a forced-choice paradigm, subjects showed "pseudoneglect", the natural tendency of neurologically intact subjects to perceive the left side of a centrally transected line as slightly longer than the right. These errors occurred more for lines in near space than for lines in far space. Magnetic stimulation of the right posterior parietal cortex or the right ventral occipital lobe selectively induced a significant shift to the right in the perceived midpoint for near- and far-space lines, respectively. The results reproduced in normal subjects the dissociation between neglect in near and far space that has been described in patients with different right-hemisphere lesions. This dissociation supports the contention that there is a dorsal/near space-ventral/far space segregation of processing in the visual system which reflects the behavioural goals of the two putative visual streams.

Adult↗

PubMedDate not supplied

Functional magnetic resonance imaging of eye dominance at 4 tesla.

We studied eye dominance in visual cortex and lateral geniculate nucleus (LGN) using functional magnetic resonance imaging (fMRI) at a very high magnetic field (4 tesla). Eight normal volunteers were studied with fMRI at 4 tesla during alternating monocular visual stimulation. The acquisition was repeated twice in 4 subjects to confirm reproducibility. In addition, magnetic resonance signal intensities during three conditions (right eye stimulation, left eye stimulation, and control condition) were compared to determine whether the observed area was truly or relatively monocular in 2 subjects. In both the individual and group analyses, the anterior striate cortex was consistently activated by the contralateral eye more than the ipsilateral eye. Additionally, we found evidence that there were areas in the bilateral LGN which were more active during the stimulation of the contralateral eye than during the stimulation of the ipsilateral eye. The activated areas were reproducible, and the mean ratio of the overlapping area was 0.71 for the repeated scans. The additional experiment revealed that the area in the anterior visual cortex could be divided into two parts, one truly monocular and the other relatively monocular. Our finding confirmed previous fMRI results at 1.5 tesla showing that eye dominance was observed in the contralateral anterior visual cortex. However, the eye dominance in the visual cortex was found not only in the most anterior area corresponding to the monocular temporal crescent but also in the more posterior area, presumably showing the greater sensitivity of the temporal visual field (nasal retina) as compared with the nasal visual field (temporal retina) in the peripheral visual field (peripheral retina). In addition, it is suggested that the nasotemporal asymmetry of the retina and the visual fields is represented in the LGN as well as in the visual cortex.

Adult↗

PubMed1991

The human atrial trabecula: effects of calcium and temperature.

The human atrial trabecular preparation is an in vitro model which has been used to evaluate drugs and conditions to which cardiac muscle is exposed perioperatively. During its development, modifications have been made to this preparation. Two important components affecting myocardial muscle contraction are temperature and calcium concentration of the muscle bath medium. Previously, these parameters were determined independently of one another and found to be 34 degrees C and 2.5 mM calcium in a minimal Tyrode's buffer with glucose. This study was undertaken to define the optimal temperature and calcium concentration which would result in the highest yield of muscles that satisfied rigorous criteria for acceptability: developed force (DF) greater than 0.8 g, resting force (RF) less than 0.7 g, cross-sectional area less than or equal to 1.0 mm2). A total of 134 trabeculae were tested using a modified Krebs-Henseleit buffer, enriched with Eagles' medium and containing either 1.25 or 2.5 mM calcium at 34 or 37 degrees C. The trabeculae contracting in 2.5 mM calcium at 37 degrees C resulted in the highest yield of 26% while those maintained at 34 degrees C in either 1.25 or 2.5 mM calcium led to 20 and 15% useful preparations respectively (P = N.S.). Trabeculae contracting at 37 degrees C in 1.25 mM calcium resulted in the poorest yield of 8% (P = 0.002). There is a small (5 to 7%), but significant (P = 0.02), decrease in DF in 1 h when all groups were analyzed together. The exclusion criteria which are applied eliminate variability due to disease and/or treatment, therefore only 20 to 25% are acceptable for study. In summary, with well-defined and stringently applied criteria, the human right atrial trabecular preparation can be a reliable and reproducible model functioning at 37 degrees C and 2.5 mM calcium for a variety of studies.

Calcium↗

PubMed1987

Tachycardia-dependent second degree AV-block in a patient with right bundle branch block.

A 55-year old male patient, with dizzy spells during everyday activity and a complete right bundle branch block as the sole electrocardiographic abnormality, reproducibly demonstrated tachycardia-dependent Mobitz Type II- and 2:1 second degree atrioventricular block. An electrophysiologic study revealed a provocable block within the distal portion of the bundle of His without evidence of a split His potential. Because of the truly tachycardia-dependent AV-block, beta-blocker medication was initiated to prevent high sinus rates during everyday activity. This therapy abolished symptoms totally.

Ajmaline↗

PubMed1985

Assessment of cardiovascular function by digital angiocardiography.

A methodology for computerized digital videoangiocardiography is briefly described. Single or biplane projection image series from the cardiovascular system are combined with the corresponding physiologic (electrocardiogram, blood pressure, etc.) reference data, digitized and stored as a block of simultaneously available information representing anatomic and functional aspects of the cardiovascular system. Simple mask mode and more complex modes of digital subtraction, image combination and manipulation techniques, as developed during the last decade, are mentioned. These techniques are primarily useful to separate the contrast bolus from the background, thereby allowing contrast enhancement with less contrast medium injected selectively, or so-called noninvasive intravenous angiocardiography. Ventricular function can be assessed by these simple digital image processing techniques. This has been proved for determining right ventricular volumes and ejection fraction with respect to reproducibility and accuracy using conventional biplane angiocardiography as reference. More complex techniques for the assessment of function, in particular blood flow distributions in the systemic circulation, are described using information from the whole digitized angiocardiographic image series by extracting time and volume parameters from the complete matrix of pixel densograms. Various modes of extraction and display of time parameters allow a generation of parametric images that display heretofore unavailable flow patterns reflecting the progress of the contrast bolus within the arterial tree. Based on an adequate temporal segmentation (for example, time segments of one cardiac cycle) and simultaneous volume determination of the circulatory structure from the area of the densogram, relative and absolute flow as well as regional flow distribution in a branching arterial system can be determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiocardiography↗

PubMed2000

3D coronary reconstruction from routine single-plane coronary angiograms: clinical validation and quantitative analysis of the right coronary artery in 100 patients.

BACKGROUND: Current coronary angiographic techniques display complex three-dimensional (3D) coronary structures in two dimensions (2D). We have developed a 3D reconstruction (3DR) algorithm using standard single-plane angiographic images that allows for 3D display of coronary structures. The purpose of this study was to validate our 3DR algorithm and quantify anatomic characteristics of the right coronary artery (RCA) in vivo. METHODS: Accuracy and reproducibility studies were performed using 3DRs of a coronary phantom and in vivo following 3DRs in 40 patients. The anatomic features of the RCA were then quantified in 100 patients. RESULTS: Comparison of length and bifurcation angles (BA) from the phantom to the 3DRs revealed good accuracy and correlation for both (r = 0.95 and 0.93 respectively), with diameter error of < 7%. In vivo, the average root mean square (RMS) error in the spatial coordinates of the vessel centerlines was 3.12 +/- 0.77 and 3.16 +/- 0.75 mm in 20 left coronary arteries (LCA) and 20 RCAs respectively. Interobserver average RMS error was 3.47 +/- 1.96 mm and intraobserver average RMS error was 3.02 +/- 1.07 and 3.44 +/- 1.57 mm for two different operators (p = NS). The average RCA length was 10.2 +/- 1.7 cm, average radius of curvature (ROC) was 52 +/- 9 degrees, and the average 3D bifurcation angle of the posterior descending artery (PDA) from the RCA was 55 +/- 22 degrees. Foreshortening (FS) of the segments of the RCA in three 'standard' projections ranged from 0-60, 0-75, and 0-82% respectively. CONCLUSIONS: Using our 3DR algorithm patient-specific anatomic characteristics can be accurately displayed and quantified, expanding the information that can be derived from routine coronary angiography.

Algorithms↗

PubMed2004

Minimally invasive, in vivo exploration of mouse small artery reactivity.

The aim of the study was to investigate in vivo arterial reactivity in the mouse hind limb using Orthogonal Polarisation Spectral (OPS) imaging, which delivers high-contrast images of vascular beds by visualizing red blood cells. After minimal skin invasion of anesthetized mice, the OPS probe was placed on the hind limb continuously superfused with physiological saline solution. Then, the response of the saphenous artery (average luminal diameter 127 +/- 3 microm; n = 15) to topical application of increasing concentrations of acetylcholine or phenylephrine was examined. Mean carotid arterial blood pressure was unaffected during the experiment. The basal diameter decreased by 70% during exposure to phenylephrine (pD2: 5.65 +/- 0.08; n = 9), while acetylcholine augmented basal diameter up to 199% (pD2: 6.55 +/- 0.12; n = 6). Application of sodium nitroprusside did not further increase arterial diameter following acetylcholine exposure. After washing out, arterial luminal diameters returned to initial values. Second exposure to vasoactive agents demonstrated that changes in diameter were reproducible with time and not different between left and right saphenous arteries. Thus, OPS imaging is an in vivo dye-free, simple and minimally invasive approach, which provides unique information regarding the behavior of vascular network within conditions of cellular and physiological homeostasis.

Acetylcholine↗

PubMed1996

Treatment of ventricular tachycardia-induced cardiomyopathy by transcatheter radiofrequency ablation.

Catheter ablation of ventricular tachycardia was successfully performed in a patient with dilated cardiomyopathy (ejection fraction 38%) and a long history of repetitive palpitations. Holter monitoring showed ventricular tachycardia that had a left bundle branch block QRS configuration with inferior axis deviation and was present for about one third of the daytime hours. At electrophysiological testing, ventricular tachycardia was reproduced by isoprenaline infusion. Radiofrequency energy delivered to the right ventricular outflow tract was successful at preventing the induction of ventricular tachycardia. Left ventricular ejection fraction had improved from 38% to 48% one month after ablation. During the follow up period of one year the patient remained free from arrhythmia on no medication. The ejection fraction was 61% one year after ablation. This report confirms that dilated cardiomyopathy can be induced by ventricular tachycardia and demonstrates that dilated cardiomyopathy can be reversed if the tachycardia is abolished by radiofrequency catheter ablation.

Adult↗

PubMed2001

Validation and utility of novel volume reduction technique for determination of parallel conductance.

The parallel conductance volume, created by the conductivity of structures surrounding the ventricular blood pool, can be estimated by using a saline dilution technique. This paper examines the use of a novel volume reduction method, during a standard vena caval preload reduction maneuver, as an alternative to the routinely used saline dilution method to calibrate conductance catheter measurements in the left (LV) and right ventricle (RV) of animals and humans. The serial reproducibility of both methods was examined by measurement of percent difference, and by assessing the coefficient of repeatability 1) between two measurements within the same subject, 2) between the two techniques, and 3) interobserver variability. The effect of ventricular size and contractile state on the volume reduction technique was also observed. It was essential to ensure the technique was not affected by inotropic state. The volume reduction technique and saline dilution method were repeated at three different loading states (baseline, 5, and 10 microg x kg(-1) x min(-1) of dobutamine). The coefficient of repeatability between serial measurements was similar for both the volume reduction and saline dilution methods, and good interobserver variability was demonstrated. The volume reduction technique was compared with the saline dilution technique over a large range of ventricular sizes. No significant difference was observed in the RV or LV of adult humans or in the LV of neonatal pigs and children. There was no significant effect on either the saline dilution or the volume reduction technique as the inotropic state increased. In conclusion, the volume reduction technique is neither affected by ventricular size nor contractile state, is repeatable between different observers, and can be used to substitute the saline dilution method when preload reduction of the ventricle is being employed.

Adult↗

PubMed2004

Ictal asomatognosia as a cause of epileptic falls: simultaneous video, EMG, and invasive EEG.

Intracranial EEG in a 33-year-old man with epilepsy with a history of falls and injuries showed seizure onset in the right posterior parietal region. Electrical stimulation of the region reproduced sudden estrangement of the left lower extremity. EMG and video recordings showed no alteration of extremity tone during the seizure, but his gait halted before he fell. Ictal asomatognosia may be a cause of falls in patients with epilepsy.

Accidental Falls↗

PubMed1997

Regional brain tissue pressure gradients created by expanding extradural temporal mass lesion.

A porcine model of regional intracranial pressure was used to compare regional brain tissue pressure (RBTP) changes during expansion of an extradural temporal mass lesion. Measurements of RBTP were obtained by placing fiberoptic intraparenchymal pressure monitors in the right and left frontal lobes (RF and LF), right and left temporal lobes (RT and LT), midbrain (MB), and cerebellum (CB). During expansion of the right temporal mass, significant RBTP gradients developed in a reproducible pattern: RT > LF = LT > RF > MB > CB. These gradients appeared early, widened as the volume of the mass increased, and persisted for the entire duration of the experiment. The study indicates that RBTP gradients develop in the presence of an extradural temporal mass lesion. The highest RBTP was recorded in the ipsilateral temporal lobe, whereas the next highest was recorded in the contralateral frontal lobe. The RBTP that was measured in either frontal lobe underestimated the temporal RBTP. These results indicated that if a frontal intraparenchymal pressure monitor is used in a patient with temporal lobe pathology, the monitor should be placed on the contralateral side and a lower threshold for therapy of increased intracranial pressure should be adopted. Furthermore, this study provides further evidence that reliance on a single frontal intraparenchymal pressure monitor may not detect all areas of elevated RBTP.

Animals↗

PubMed1992

[Objective evaluation of sclerodermic skin using the slip-test. Results and validation with 30 patients and 60 controls].

The slip test is a non-invasive way to objectively evaluate the extent of scleroderma by measuring the "slipping" of the skin over an underlying bone. The results obtained in 30 scleroderma patients and 60 controls (178 tests due to multiple measurements) were analyzed to determine which test sites show a significant difference between patients and controls (Student's t-test) and which sites are the most discriminating for the diagnosis of the disease (multivariate analysis). Patient values were clearly distinct from those of controls. The best sites (defined by p < 0.05) were: the mandible, the second and first phalanges of the middle finger, the hands, the forearms, the epicondyles, the sternum, the iliac crests, the patellae, the tibias (the upper and lower fourths) and the feet; in all, 23 sites to which can be added the opening of the mouth (measurement of the maximal interlabial distance), which proved to be a reliable parameter. Multiple regression analysis yielded an equation that identified patients with scleroderma based on 4 variables (right forearm, right iliac crest, sternum and right rib). The slip test is thus the first reproducible quantitative test able to confirm and quantify clinical impressions in scleroderma. It is entirely able to objectively monitor the evolution of the disease under treatment. Nevertheless, complementary studies are needed to verify whether the slip test, which can be performed in 20 minutes during an office visit, can be used advantageously in the routine clinical evaluation of scleroderma.

Adult↗

PubMed2004

[Change in Toll-like receptor 4 expression on interstitial macrophages in acute lung injury].

OBJECTIVE: To observe changes in the level of Toll-like receptor 4 (TLR4) mRNA and the expression of TLR4 protein in interstitial macrophages in serious thoracic injury. METHODS: A rat model of severe thoracic trauma was reproduced,then interstitial macrophages were isolated and collected by enzymatic digestion before and after trauma cultured. TLR4 mRNA and the expression of TLR4 protein were measured by Northern and Western blotting before trauma and 2, 4, 8, 16, 24 hours after trauma. RESULTS: A stable and reliable severe thoracic trauma model was successfully reproduced with 400 kPa impact on the up-right chest of rat by a multiple-function collision apparatus. The expression was up-regulated by trauma and the highest expression of interstitial macrophages occurred 8, 16 hours after the trauma, and returned to normal range at 24 hours. CONCLUSION: The up-regulation of TLR4 might participate in the pathological process of excessive inflammation after trauma to the lung.

Acute Lung Injury↗

PubMed2003

Electrical stimulation induced cervical medial branch referral patterns.

STUDY DESIGN: Electrical stimulation of the right cervical medial branches with or without the third occipital nerves was performed in nine subjects for a total of forty-eight medial branches and eight third occipital nerves. The referral patterns of each nerve or nerve branch was mapped on a human line diagram. These diagrams were compared to facet joint (zygapophyseal joint, facet joint), myofascial, and discogenic referral patterns already published by various authors. OBJECTIVE: [corrected] To determine the referral patterns of the cervical medial branches and the third occipital nerve. HYPOTHESIS: The cervical medial branch referral patterns created by electrical stimulation may differ from those reported from other etiologies and may prove to be useful when considering various cervical pain syndromes. METHODS: The third occipital nerve and third through eighth medial branches of the cervical posterior rami of nine subjects with and without a history of neck pain were electrically stimulated under fluoroscopic imaging. All subjects were blinded to the level of stimulation, and the referral patterns of each individual were mapped out on a human line drawing by the primary author of this study. These referral patterns were compared to referral patterns reported from other etiologies by various authors. CONCLUSIONS: Electrical stimulation of the third occipital nerve as well as the medial branch of the right C3-C8 posterior primary rami create discrete, reproducible referral patterns which differ from those reported from other etiologies by various authors.

Journal Article↗

PubMed1989

[Autotransplantation: technic and long-term results].

Dental transplantation can be a useful and efficious technic. It was first described by Ambroise Pare and the authors have had over 12 years success and failures enough to present clinical cases and illustrations of the surgery and the orthodontic treatment. Success depends essentially on the right indication, the time and the exact methodical technic, reproducible in a treatment plan.

Adolescent↗