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Results for “The Right to Reproduce”

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At least 613 records · Page 34Linked to original sources

PubMed2002

Anatomical localization and intra-subject reproducibility of laser evoked potential source in cingulate cortex, using a realistic head model.

OBJECTIVES: To (i) accurately localize the cingulate source of late laser evoked potentials (LEPs) using a realistic head model incorporating the individual's anatomy and (ii) assess the within-subject reproducibility of this source. METHODS: Late LEPs, elicited by painful CO2 laser stimulation of the right forearm, were recorded from 62 electrodes in one healthy subject. This was repeated 9 times, over 3 different days. Dipole source localization (CURRY 4.0) was performed on the most prominent (P2) peak of each LEP data set, using a head model derived from the subject's structural magnetic resonance image. RESULTS: In all cases the P2 LEP peak was best explained by a dipole located close to the border of the caudal division of left anterior cingulate cortex with left posterior cingulate cortex (mean residual variance was 1.7+/-0.4%). The maximum standard deviation from the mean dipole location was 3.2 mm. CONCLUSIONS: This study demonstrates that the location of the cingulate source of late LEPs is highly reproducible within this subject, when analyzed in this way, and suggests involvement of caudal cingulate regions in pain processing.

Adult↗

PubMed2000

Doppler-derived acceleration rate of right ventricular early filling reliably predicts mean right atrial pressure at baseline and after loading manipulations in patients with chronic heart failure.

BACKGROUND: We investigated whether Doppler-derived variables of tricuspid flow could estimate mean right atrial pressure and monitor its changes after loading manipulations in patients with chronic heart failure. METHODS: Simultaneous mean right atrial pressure (Swan-Ganz catheterization) and tricuspid Doppler recordings were initially evaluated in 136 patients (23 with atrial fibrillation) with chronic heart failure and severe left ventricular systolic dysfunction, and then were repeated in 18 patients after unloading (sodium nitroprusside infusion) and in 13 patients after overloading (active leg elevation) manipulations. RESULTS: A significant correlation was observed between mean right atrial pressure and peak E velocity (r = 0.70), early deceleration time (r = -0.72) and acceleration time (r = -0.75). However, the best correlation found was between the acceleration rate of early flow and mean right atrial pressure, and it was identical in patients in sinus rhythm or with atrial fibrillation (r = 0.98). Moreover, after acute effective unloading or overloading manipulations, although all Doppler tricuspid variables changed significantly, the acceleration rate of early flow still emerged as the strongest independent predictor of mean right atrial pressure (r = 0.95 and 0.99, respectively). CONCLUSIONS: Doppler-derived acceleration rate of early diastolic tricuspid flow is a powerful tool to predict mean right atrial pressure and to monitor its changes after loading manipulations.

Adult↗

PubMed2006

Assessment of pulmonary valve and right ventricular outflow tract with real-time three-dimensional echocardiography.

AIM: Assessment of pulmonary valve (PV) and right ventricular outflow tract (RVOT) using real-time 3-dimensional echocardiography (RT3DE). METHODS: Two-dimensional echocardiography (2DE) and RT3DE were performed in 50 patients with congenital heart disease (mean age 32 +/- 9.5 years, 60% female). Measurements were obtained at parasternal views: short axis (PSAX) at aortic valve level and long axis (PLAX) with superior tilting. RT3DE visualization was evaluated by 4-point score (1: not visualized, 2: inadequate, 3: sufficient, and 4: excellent). Diameters of PV annulus (PVAD), and RVOT (RVOTD) were measured by both 2DE and RT3DE, while areas (PVAA) and (RVOTA) by RT3DE only. RESULTS: By RT3DE, PV was visualized sufficiently in 68% and RVOT excellently in 40%. PVAD and PVAA were measured in 88%. RVOTD and PVAD by 2DE at PLAX were significantly higher than PSAX (P < 0.0001) and lower than that by RT3DE (P < 0.001). CONCLUSION: RT3DE helps in RVOT and PV assessment adding more details supplemental to 2DE.

Adult↗

PubMed2000

Right ventricular volume measurement: can conductance do it better?

The measurement of right ventricular volume will be reviewed with special reference to the conductance catheter technique. The historical development of the intracavitary impedance technique will be described along with the theory of the multielectrode conductance method. The major potential advantage of this technique is its ability to measure dynamic volume change during the cardiac cycle. This enables a real time beat to beat assessment of ventricular volume in addition to providing continuous recordings during loading manoeuvres performed on the ventricle. However, the conductance catheter technique is based on the assumption that the electric field produced by the catheter is homogeneous and parallel to the long axis of the ventricle, and the current, created by the excitation electrodes of the catheter, is contained within the ventricular cavity. The measurement of these two calibration factors (known as parallel conductance volume (V(C)) and dimensionless slope factor (alpha)), along with the effects of changes in blood resistivity and the orientation of the catheter on the measurement of absolute volume, will be described. Furthermore, some of the clinical applications of the technique in adults and children with heart disease will be outlined.

Cardiac Catheterization↗

PubMed1997

Elastic energy as an index of right ventricular filling.

BACKGROUND: Right ventricle (RV) preload assessment remains controversial because the complexity of RV geometry is an obstacle to wall stress modeling. We developed a method to evaluate end-diastolic RV elastic energy (EL), a variable that integrates all the stretching effects of venous return and that can be easily estimated at the bedside from the area under the diastolic RV pressure-volume curve. The purpose of this study was to compare the clinical utility of EL and of the two conventional variables used to assess RV filling, ie, right atrial pressure (Pra) and RV end-diastolic volume (EDV). METHOD: We studied 26 postoperative patients who required a rapid fluid challenge. Energetics were evaluated by constructing the RV pressure-volume loop at the bedside using right heart catheterization with RV ejection fraction (EF) derivation. Correlations between RV filling and RV performance (ejection and mechanical efficiency) were studied. RV filling indexes were Pra, EDV, and EL. Indexes of RV ejection were stroke volume (SV), RV stroke work (RVSW), mechanical energy expenditure during ejection (EM), and total energy expenditure of contraction (ET). Indexes of RV mechanical efficiency were EF and the EM/ET ratio. RESULTS: Three important results were obtained. First, among RV ejection indexes, those that correlated best with RV filling indexes were EM and ET. Second, we found significant linear relationships between improved RV filling, as assessed by changes in EDV and EL, and improved RV ejection, as assessed by changes in SV, RVSW, EM, or ET. Third, changes in EDV and EL also predicted improved mechanical efficiency, as assessed by changes in EF and EM/ET. In, all situations, changes in EL yielded the strongest correlations. CONCLUSIONS: Derivation of EL is simple and appears to be the best clinical means of assessing Starling's law of the heart for the RV.

Adult↗

PubMed1997

An fMRI study of the human cortical motor system response to increasing functional demands.

Functional magnetic resonance imaging (fMRI) was used to study activation changes in the human primary motor-sensory areas (MAs), supplementary motor areas (SMAs), premotor areas (PMAs) and the superior and inferior parietal areas (SPAs, IPAs) during right hand finger movements as the rate, force and complexity of movement were varied. A preliminary reproducibility study of a single subject doing the same repetitive index finger movements in nine different sessions over a six week period demonstrated highly consistent and highly localized activation in the contralateral MA. ANOVAs demonstrated highly significant main effects of increasing the force and complexity of movement, thereby illustrating the distributed and integrated systemic character of the cortical motor system. Interactions between brain region and the rate and complexity of movements suggested functional specialization of some components of the system. Increasing the rate of movement led to increased activity only in the contralateral MA; increasing complexity led to greater increases in activity in the left and right SPAs and the left IPA than in other areas. Although activation was evident in varying degree throughout the multiple motor areas, only the MAs showed consistent lateralization of activation.

Adult↗

PubMed2006

Transient evoked otoacoustic emissions.

OBJECTIVE: The purpose of this study was to collect parametric measures of TEOAEs in normal hearing children of various age-groups and to establish a normative baseline for Transient Evoked Otoacoustic Emissions (TEOAEs). METHODS: Sixty subjects were investigated in three age-groups: neonates, 0-1 month; infants, 1 month-1 year; and children, 1-6 years. Each group comprised of 20 subjects. All the subjects underwent medical examination by a pediatrician and an ENT surgeon. Screening for hearing was done by immittance testing, behavior observation and conditioned play audiometry. The TEOAEs were analyzed for the parameters of amplitude, cross-correlation (wave reproducibility) and signal-to-noise ratio (SNR). RESULTS: There was no difference between the mean amplitudes of the right and left ears in the groups. The females in the neonates group had higher emission amplitudes than the males. The mean amplitude of the subjects in the neonates group was significantly higher than the subjects in the infants or children groups. The cross correlation (wave reproducibility) was constant across the age. The mean SNR for all the subjects were well above 3 dB at frequencies 1.5 k, 2 k, 3 k and 4 kHz. The neonates group showed the lowest SNR ranging between 3.47 to 9.62 dB. The infants group showed the highest SNR ranging between 6.13 to 13.11 dB. CONCLUSION: The TEOAEs response measures of SNR and cross correlation, at frequency bands 1.5, 2, 3 and 4 kHz, may provide more reliable outcomes than TEOAEs amplitude. Subjects in the age range of 0-1 month show lower SNRs than those in higher age ranges. The values can be used as normative data for screening and diagnostic purposes in the pediatric population.

Acoustic Impedance Tests↗

PubMed2000

Gauge symmetry, chirality and parity effects in four-particle systems: Coulomb's law as a universal function for diatomic molecules.

Following recent work in search for a universal function (Van Hooydonk, Eur. J. Inorg. Chem., (1999), 1617), we test four symmetric +/- a(n)Rn potentials for reproducing molecular potential energy curves (PECs). Classical gauge symmetry for 1/R-potentials results in generic left right asymmetric PECs. A pair of symmetric perturbed Coulomb potentials is quantitatively in accordance with observed PECs. For a bond, a four-particle system, charge inversion (a parity effect, atom chirality) is the key to explain this shape generically. A parity adapted Hamiltonian reduces from ten to two terms and to a soluble Bohr-like formula, a Kratzer (1 - Re/R)2 potential. The result is similar to the combined action of spin and wave function symmetry upon the Hamiltonian in Heitler-London theory. Analytical perturbed Coulomb functions varying with (1 - Re/R) scale attractive and repulsive branches of PECs for 13 bonds H2, HF, LiH, KH, AuH, Li2, LiF, KLi, NaCs, Rb2, RbCs, Cs2 and I2 in a single straight line. The 400 turning points for 13 bonds are reproduced with a deviation of 0.007 A at both branches. For 230 points at the repulsive side, the deviation is 0.003 A. The perturbed electrostatic Coulomb law is a universal molecular function. Ab initio zero molecular parameter functions give PECs of acceptable quality, just using atomic ionisation energies. The function can be used as a model potential for inverting levels and gives a first principle's comparison of short- and long-range interactions, important for the study of cold atoms. Wave-packet dynamics, femto-chemistry applied to the crossing of covalent and ionic curves, can provide evidence for this theory. We anticipate this scale/shape invariant scheme applies to smaller scales in nuclear and high-energy particle physics. For larger gravitational scales (Newton 1/R potentials), problems with super-unification are discussed. Reactions between hydrogen and antihydrogen, feasible in the near future, will probably produce normal H2.

Cesium↗

PubMed1999

Real-time, three-dimensional echocardiography: feasibility of dynamic right ventricular volume measurement with saline contrast.

BACKGROUND: The asymmetry and complex shape of the right ventricle have made it difficult to determine right ventricular (RV) volume with 2-dimensional echocardiography. Three-dimensional cardiac imaging improves visualization of cardiac anatomy but is also complex and time consuming. A newly developed volumetric scanning system holds promise of obviating past limitations. METHODS: Real-time, transthoracic 3-dimensional echocardiographic images of the right ventricle were obtained with a high-speed volumetric ultrasound system that uses a 16:1 parallel processing schema from a 2.5 MHz matrix phased-array scanner to interrogate an entire pyramidal volume in real time. The instrumentation was used to measure RV volume in 8 excised canine hearts; dynamic real-time 3-dimensional images were also obtained from 14 normal subjects. RESULTS: Three-dimensional images were obtained in vitro and in vivo during intravenous hand-agitated saline injection to determine RV volumes. The RV volumes by real-time 3-dimensional echocardiography are well correlated with those of drained in vitro (y = 1.26x - 9.92, r = 0.97, P <.0001, standard error of the estimate = 3.26 mL). For human subjects, the end-diastolic and end-systolic RV volumes were calculated by tracing serial cross-sectional, inclined C scans; functional data were validated by comparing the scans with conventional 2-dimensional echocardiographic indexes of left ventricular stroke volume. CONCLUSIONS: These data indicate that RV volume measurements of excised heart by real-time 3-dimensional echocardiography are accurate and that beat-to-beat RV quantitative measurement applying this imaging method is possible. The new application of real-time 3-dimensional echocardiography presents the opportunity to develop new descriptors of cardiac performance.

Animals↗

PubMedDate not supplied

Reproducibility of central venous pressures in supine and lateral positions: a pilot evaluation of the phlebostatic axis in critically ill patients.

OBJECTIVE: To determine if the phlebostatic axis (PA) can be used to obtain reproducible central venous pressures (CVP) in laterally positioned critically ill patients. DESIGN: A quasi-experimental study design was used. The outcome variable was central venous pressure. The explanatory variables were position (supine, 30 degrees right lateral, 30 degrees left lateral) and transducer leveling procedure (supine PA, upper PA, dependent PA). Each subject was used as his or her own control. SETTING: General intensive care unit of a 929 bed metropolitan teaching hospital in New South Wales, Australia. SUBJECTS: A convenience sample of 25 critically ill patients (15 men and 10 women) with an average age of 59.6 years +/- 15.2. METHOD: Each subject's baseline CVP range was collected over a 25-minute period in a supine position. CVP measurements were then obtained in the left and right lateral positions (initial lateral position alternated for each subsequent subject). When the subject was lateral, three CVP readings corresponding to the three transducer leveling procedures were taken. DATA ANALYSIS: One-way repeated measures analysis of variance (one for each leveling procedure) were performed. Clinical significance was deemed evident when the lateral CVP measurement exceeded the baseline range. RESULTS: Statistically significant changes were associated with the upper PA (p < 0.001) and the dependent PA (p < 0.001). Only the supine PA yielded statistically nonsignificant changes in CVP (p = 0.073). However, power analysis indicated that the results were not conclusive (power = 0.520). Clinical significance was determined in 100% and 92% of subjects in the left lateral and right lateral positions, respectively, when using the upper PA whereas the dependent PA yielded clinical significance in all (100%) subjects. Clinical significance was seen in 46% and 42% of subjects for the left lateral and right lateral positions, respectively, when the supine PA was used. CONCLUSION: Of the three leveling procedures, the supine PA yielded the most reproducible CVP measures. However, further studies are required before the supine PA can be recommended as a valid and reliable transducer position for CVP measurement in laterally positioned patients.

Adult↗

PubMedDate not supplied

Feasibility of a two-dimensional echocardiographic method for the clinical assessment of right ventricular volume and function in children.

The relative ease of acquisition and safety of two-dimensional echocardiography has established it as the mainstay for routine cardiac imaging. Translation of imaging data into useful quantitative information, however, requires fitting the ventricle to a specific geometric model. Because of its complex shape and anterior position, many attempts at right ventricular quantitation by two-dimensional echocardiography have been criticized as impractical and not reproducible. A simple method incorporating subcostal and apical imaging was introduced in 1984. This approach appeared to combine accuracy and practicability but was never validated in a clinical setting because of the difficulties of subcostal imaging in adults. This study assessed the feasibility and accuracy of this technique in the pediatric population. Results of volume comparison to values derived by magnetic resonance imaging were r = 0.96, standard error of the estimate (SEE) = 19.3 ml, and mean difference = 15 +/- 19.4 ml and r = 0.97, SEE = 12.3 ml, and bias = 5 +/- 11.8 ml for diastolic and systolic volumes, respectively. Comparison of estimates of ejection fraction with magnetic resonance imaging demonstrated r = 0.90, SEE = 5.9%, and bias = 3% +/- 5.7%. Interobserver and intraobserver variability was 9.9% and 8.2%, respectively, for systolic volumes and 11.5% and 8.9%, respectively, for diastolic volumes. Evaluation of right ventricular size and function by this approach is comparable to determinations by magnetic resonance imaging and may be clinically useful in the management of pediatric patients.

Adolescent↗

PubMed1977

Reproducibility of thallium-201 myocardial imaging.

Seventy-six thallium-201 myocardial perfusion studies were performed on twenty-five patients to assess their reproducibility and the effect ofvarying the level of exercise on the results of imaging. Each patient had a thallium-201 study at rest. Fourteen patients had studies on two occasions at maximum exercise, and twelve patients had studies both at light and at maximum exercise. Of 70 segments in the 14 patients assessed on each of two maximum exercise tests, 64 (91%) were reproducible. Only 53% (16/30) of the ischemic defects present at maximum exercise were seen in the light exercise study in the 12 patients assessed at two levels of exercise. Correlation of perfusion defects with arteriographically proven significant coronary stenosis was good for the left anterior descending and right coronary arteries, but not as good for circumflex artery disease. Thallium-201 myocardial imaging at maximum exercise is reproducible within acceptable limits, but careful attention to exercise technique is essential for valid comparative studies.

Adult↗

PubMed2004

Evaluation of right ventricular dysfunction in patients with cardiac amyloidosis using Tei index.

BACKGROUND: Cardiac amyloidosis is an infiltrative disease causing predominant diastolic dysfunction and systolic dysfunction at its advanced stage. Right ventricular (RV) dysfunction is an independent predictor of poor prognosis in congestive heart failure and cardiomyopathies. However, the assessment of RV function is still technically difficult because of the complicated geometry of the RV. The recently proposed Tei index, obtained from the cardiac time interval analysis, allows noninvasive and quantitative estimation of global ventricular function without geometric evaluation. Therefore, this study was designed to assess RV function for patients with cardiac amyloidosis. METHODS: Study patients consisted of 30 consecutive patients with biopsy specimen-proven cardiac amyloidosis and 50 control subjects. Patients were classified as having early or advanced stage of cardiac amyloidosis on the basis of mean left ventricular wall thickness < 15 mm or >/= 15 mm. Tei index, defined as the sum of isovolumetric contraction and relaxation time divided by ejection time, was obtained from tricuspid and pulmonary Doppler flow velocity. RESULTS: RV Tei index was significantly increased for patients with cardiac amyloidosis (0.54 +/- 0.16 vs 0.28 +/- 0.05, amyloidosis vs control, P <.001). The incidences of abnormal RV isovolumetric contraction time, ejection time, isovolumetric relaxation time, and Tei index in all patients with cardiac amyloidosis were 63%, 43%, 73%, and 83%, respectively. The same incidences were 50%, 13%, 63%, and 75% in the early stage and 68%, 54%, 77%, and 86% in the advanced stage, respectively. CONCLUSION: Patients with cardiac amyloidosis frequently have RV dysfunction even in its early stage. Tei index allows simple, noninvasive, and nongeometric estimation of RV dysfunction in patients with cardiac amyloidosis.

Adult↗

PubMed1997

Reproducibility of shear rate and shear stress assessment by means of ultrasound in the common carotid artery of young human males and females.

In the present study, the reliability of an ultrasonic shear rate estimating system, in terms of intrasubject intrasession, intersubject intrasession and intersubject intersession variability coefficients for the assessment of wall shear rate (WSR) in the common carotid artery (CCA) was determined in eight presumed healthy volunteers. Measurements were performed on consecutive days (day 1, day 2 and day 7). To investigate whether there were differences in WSR due to gender, dynamic WSR in the CCA was assessed in 11 presumed healthy males (mean age 24 y) and 11 presumed healthy females (mean age 25 y). Wall shear stress (WSS) was estimated from WSR and calculated whole blood viscosity. The average intrasubject intrasession variability was about 15% for peak WSR and about 12% for mean WSR. The intersubject intrasession variability for peak WSR decreased from 19% on day 1 to 16% on day 7 and for mean WSR from 17% on day 1 to 11% on day 7. The intersubject intersession variability is on the order of 5% for peak WSR and about 4% for mean WSR. No significant differences could be detected between peak and mean WSR values on day 1, day 2 and day 7, indicating good short- and medium-term intersubject intersession reproducibilities. No differences in peak and mean WSR were found between the left and the right CCA in the male group as well as in the female group. Mean WSS was similar in males (1.3 +/- 0.3 Pa) and in females (1.2 +/- 0.2 Pa), but peak WSS was slightly, but significantly, higher in males (4.3 +/- 1.3 Pa) than in females (3.3 +/- 0.7 Pa). It can be concluded that peak and mean WSR can be reliably determined noninvasively using ultrasound.

Adult↗

PubMed1998

[In vivo study of kinematics of the elbow using electromagnetic goniometer].

We used an electromagnetic goniometer to study the angular and translations displacements between the humerus and the 2 bones of the forearm. The electromagnetic gionometer allows acquisition of the coordinates and analysis of the 6 degrees of motion. To validate our external fixation apparatus, we used a fresh body upper limb. At first, a series of measurements was conducted with the apparatus. We then performed a series of measurements, by fixing the transmitter and receiver with external fixation pins directly inserted into the bones of the arm and forearm. To assess the reproducibility of our method, we chose a healthy subject. We performed 20 measurements over his right and left elbows. In order to study normal elbow kinematics, we performed measurements on 10 healthy subjects. The study of rotation showed that the apparatus was adapted to measure flexion-extension. It limited pronation-supination movement to about 26.7 degrees. Abduction was increased by 19.7 degrees by our apparatus during flexion-extension, but abduction was reliable within a 2 degrees range for pronation-supination. The sliding movements recorded during flexion-extension were reliable within approximately 3 mm for frontal translations, 6 mm for fitting, and 1 mm for external translations. For the sliding movements recorded in pronation-supination, frontal translations were reliable within about 7 mm, fitting was reliable within 1.9 mm and external translations were reliable within about 2.9 mm. During flexion-extension of the elbow, flexion-extension, frontal translations and external translations were reproducible. The reproducibility test showed that only 6 measurements were reproducible. The kinematic elbow study of a healthy subject showed that the average amplitude of flexion-extension was close to the measurement observed with the manual goniometer. The results in the healthy subject showed that the elbow is more stable during pronation-supination than during flexion-extension. This preliminary study should allow us, in the near future, to study elbow prosthesis kinematics.

Cadaver↗

PubMed1998

Effect of inhaled nitric oxide on intrapulmonary right-to-left-shunting in two rabbit models of saline lavage induced surfactant deficiency and meconium instillation.

Marked hypoxia secondary to intrapulmonary right-to-left shunting is a characteristic of respiratory failure in human neonates and can sometimes be complicated by additional extrapulmonary right-to-left shunting. To investigate the effect of inhaled nitric oxide (iNO) on intrapulmonary shunting, two typical pulmonary diseases of the newborn (respiratory distress syndrome and meconium aspiration) were reproduced in 32 mechanically ventilated rabbits weighing approximately 2 kg each. After tracheotomy, catheters were inserted into a jugular vein, a carotid artery and the right ventricle (to measure systolic right ventricular pressure [SRVP] and mixed venous oxygen content for calculation of shunt by Fick equation). Repeated airway lavages (LAV) with normal saline or repeated instillations of a suspension of human meconium (MEC) were continued until both the a/A-ratio was < or =0.14 and a peak inspiratory pressure > or =22 mbar was needed to keep the tidal volume constant at 10 ml/kg of body weight. Measurements of shunt, SRVP, systolic systemic pressure, physiological dead space, tidal volume and a ventilation index were performed before and after completion of lung damage and at 20 and 60 min after administering iNO at 80 ppm. Four groups of rabbits were studied (n=8 in each group): LAV control and intervention, Mec control and intervention. 60 min after starting iNO, there was a decrease in shunt (LAV: 67.6%+/-[SD] 11.3% vs 56.2+/-16.4, P=0.05; MEC: 52.6+/-6.3 vs 44.3+/-8.3, P < 0.05), in SRVP (LAV: 29.7 mmHg +/-10.1 mmHg vs 20.0+/-8.2, P < 0.01; MEC: 25.1+/-4.4 vs 22.3+/-5.0, P=0.46) and in dead space (% of tidal volume, LAV: 32.7%+/-10.5% vs 25.9+/-10.1, P < 0.01; MEC: 26.1+/-16.6 vs 18.9+/-10.1, P=0.05). These results demonstrate that iNO decreases intrapulmonary shunt (as well as SRVP and dead space). We suggest that iNO may be beneficial in human newborns with severe respiratory failure even if no extrapulmonary shunting via ductus or foramen ovale is apparent.

Administration, Inhalation↗

PubMed1997

Noninvasive assessment of right ventricular diastolic function by electrical impedance tomography.

STUDY OBJECTIVES: Electrical impedance tomography (EIT) offers the possibility to study blood volume changes within the right atrium during the cardiac cycle. The aim of this study was to determine the applicability of EIT in the assessment of right ventricular diastolic function in COPD. DESIGN: By means of region of interest analysis, impedance changes within the right atrium during the cardiac cycle were plotted as a function of time. As a diastolic index of the right ventricle, the right atrium emptying volume (RAEV), defined as the ratio between the volume change during the rapid filling phase relative to the total ventricular filling volume, was calculated. In a first study, the validity of the EIT method was assessed by comparison of the RAEV measured by EIT and MRI in a group of eight patients with severe COPD and seven control subjects. A second study was undertaken to assess the relation between RAEV and pulmonary artery pressure in a group of 27 patients measured by right-sided heart catheterization. RESULTS: The correlation coefficient between RAEV measured with MRI and EIT was 0.78. The difference between RAEV measured by MRI and EIT was 8.3 +/- 15.7% (mean +/- SD) for the control subjects and 3.5 +/- 10.9% for the COPD patients. RAEV values measured by EIT and MRI were larger in the control group (47.1 +/- 7.6%) compared with the patient group (38.1 +/- 10.4%). There was a clear nonlinear relationship between RAEV and the pulmonary artery pressure (y = 315 x-0.64, r = 0.83, p < 0.001). CONCLUSION: Our results indicate that RAEV measured by EIT is a useful noninvasive and inexpensive method for assessing right ventricular diastolic function in COPD patients.

Blood Pressure↗

PubMed1995

[Assessment of right ventricular function by magnetic resonance imaging of old myocardial infarction].

The usefulness of magnetic resonance imaging (MRI) for estimating right ventricular function and the influence of left ventricular dysfunction on the performance of the right ventricle were assessed in 43 patients with chronic myocardial infarction (MI) and 14 control subjects (N) using electrocardiography-gated MRI and cardiac catheterization. Patients with MI were divided into three groups according to the location of the coronary lesions; 22 patients with left coronary artery lesion (LCA group), 13 with right coronary artery lesion (RCA group), and 8 with both left and right coronary artery lesions (L+R group). The right ventricular end-diastolic volume (RVEDV) and right ventricular ejection fraction (RVEF) were measured by Simpson's rule algorithm on transverse images of the right ventricle obtained at the end-systolic and end-diastolic phases. In 34 of the 43 patients, the same parameters of right ventricular function were calculated by the thermodilution method using a Swan-Ganz catheter with rapid response thermistor. Left ventricular ejection fraction (LVEF) and end-diastolic volume were determined from left ventriculography. The intraobserver reproducibility (11 cases, r = 0.97) and interobserver reproducibility (11 cases, r = 0.92) of RVEF measured by MRI were excellent. The RVEF and RVEDV determined from MRI were significantly correlated with those from the thermodilution method (RVEF: r = 0.56, RVEDV: r = 0.52). There was no difference in right ventricular end-diastolic volume index in any patient group. The RVEF was decreased in the L+R (41.0 +/- 4.5%, p < 0.01) and RCA (45.9 +/- 6.6%) groups, but there was no difference between the LCA (50.6 +/- 6.6%) and N (48.9 +/- 4.3%) groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗