The Experts below are selected from a list of 90147 Experts worldwide ranked by ideXlab platform
A N Redington - One of the best experts on this subject based on the ideXlab platform.
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increased airway Pressure and simulated branch pulmonary artery stenosis increase pulmonary regurgitation after repair of tetralogy of fallot real time analysis with a conductance catheter technique
Circulation, 1997Co-Authors: Rajiv Chaturvedi, Philip J Kilner, Paul A White, Andrew Bishop, Richard Szwarc, A N RedingtonAbstract:Background Pulmonary regurgitation (PR) is an important determinant of outcome after repair of tetralogy of Fallot. Baseline PR was measured by magnetic resonance (MR) phase velocity mapping and from real-time right Ventricular Pressure-volume loops with a conductance catheter. Subsequently, the impact of two loading maneuvers (increased airway Pressure, simulated branch pulmonary artery stenosis) on PR was assessed by the conductance catheter method. Methods and Results Thirteen patients, 3 to 35 years after tetralogy of Fallot repair or pulmonary valvotomy, had PR measured by MR phase velocity mapping while breathing spontaneously. During catheterization under general anesthesia, PR was estimated from right Ventricular Pressure-volume loops generated by conductance and microtip Pressure catheters. The effect of increased airway Pressure (continuous positive airway Pressure, 20 cm H2O; n=12) and simulated branch pulmonary artery stenosis (transient balloon occlusion of a branch pulmonary artery, n=7) was...
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increased airway Pressure and simulated branch pulmonary artery stenosis increase pulmonary regurgitation after repair of tetralogy of fallot real time analysis with a conductance catheter technique
Circulation, 1997Co-Authors: Rajiv R Chaturvedi, Philip J Kilner, Paul A White, Andrew Bishop, Richard Szwarc, A N RedingtonAbstract:BACKGROUND: Pulmonary regurgitation (PR) is an important determinant of outcome after repair of tetralogy of Fallot. Baseline PR was measured by magnetic resonance (MR) phase velocity mapping and from real-time right Ventricular Pressure-volume loops with a conductance catheter. Subsequently, the impact of two loading maneuvers (increased airway Pressure, simulated branch pulmonary artery stenosis) on PR was assessed by the conductance catheter method. METHODS AND RESULTS: Thirteen patients, 3 to 35 years after tetralogy of Fallot repair or pulmonary valvotomy, had PR measured by MR phase velocity mapping while breathing spontaneously. During catheterization under general anesthesia. PR was estimated from right Ventricular Pressure-volume loops generated by conductance and microtip Pressure catheters. The effect of increased airway Pressure (continuous positive airway Pressure, 20 cm H2O; n = 12) and simulated branch pulmonary artery stenosis (transient balloon occlusion of a branch pulmonary artery, n = 7) was measured. Basal PR fraction derived by MR and from right Ventricular Pressure-volume loops had a correlation coefficient of .76 and mean of differences of 2.0 +/- 18.2% (95% limits of agreement). Increased airway Pressure increased PR (16.3 +/- 11.4% to 25.7 +/- 17.3%, P < .01). Simulated branch pulmonary artery stenosis increased right Ventricular end-systolic Pressure (69.1 +/- 21.4 to 78.7 +/- 23.1 mm Hg, P < .05) and PR (27.5 +/- 11.3% to 36.9 +/- 12.8%, P < .05). CONCLUSIONS: There was reasonable agreement between MR phase velocity-derived PR fraction and that obtained from right Ventricular Pressure-volume loops generated by use of conductance and Pressure-microtip catheters. Exacerbation of PR by increased airway Pressure and branch pulmonary stenosis may be relevant to the acute postoperative and long-term management, respectively, of patients after repair of tetralogy of Fallot.
Nobuyuki Ohte - One of the best experts on this subject based on the ideXlab platform.
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abstract 18753 intra left Ventricular Pressure difference during atrial contraction is a useful parameter to assess left Ventricular end diastolic Pressure
Circulation, 2017Co-Authors: Kazuaki Wakami, Keisuke Muto, Junki Yamamoto, Shohei Kikuchi, Toshihiko Goto, Hidekatsu Fukuta, Shinro Saiki, Hiroshi Fujita, Nobuyuki OhteAbstract:Background: Vector Flow Mapping (VFM TM, Hitachi) enables us to obtain intra-left Ventricular Pressure difference (IVPD) from blood flow velocity data set acquired by color Doppler imaging (CDI). W...
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abstract 15495 elevated left Ventricular end diastolic Pressure reduces intra left Ventricular Pressure gradient during atrial contraction
Circulation, 2016Co-Authors: Kazuaki Wakami, Marina Ishida, Tomoyuki Banno, Keisuke Muto, Junki Yamamoto, Shohei Kikuchi, Koji Yamamoto, Toshihiko Goto, Hidekatsu Fukuta, Nobuyuki OhteAbstract:Background: Vector Flow Mapping (VFM, Hitachi-Aloka) was recently developed to obtain intra-left Ventricular Pressure gradient (IVPG) from the data set of blood flow velocity vectors obtained in th...
James D. Thomas - One of the best experts on this subject based on the ideXlab platform.
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noninvasive assessment of the Ventricular relaxation time constant τ in humans by doppler echocardiography
Circulation, 1997Co-Authors: Gregory M Scalia, James D. Thomas, Neil L Greenberg, Patrick M Mccarthy, Pieter M VandervoortAbstract:Background The time constant of Ventricular relaxation (τ) is a quantitative measure of diastolic performance requiring intraVentricular Pressure recording. This study validates in humans an equation relating τ to left Ventricular Pressure at peak −dP/dt (P0), Pressure at mitral valve opening (PMV), and isovolumic relaxation time (IVRTinv). The clinically obtainable parameters peak systolic blood Pressure (Ps), mean left atrial Pressure (PLA), and Doppler-derived IVRT (IVRTDopp) are then substituted into this equation to obtain τDopp noninvasively. Methods and Results High-fidelity left atrial and left Ventricular Pressure recordings with simultaneous Doppler by transesophageal echocardiography were obtained from 11 patients during cardiac surgery. Direct curve fitting to the left Ventricular Pressure trace by Levenberg-Marquardt regression assuming a zero asymptote generated τLM, the “gold standard” against which τcalc {IVRTinv/[ln(P0)−ln(PMV)]} and τDopp {IVRTDopp/[ln(Ps)−ln(PLA)]} were compared. For 12...
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Continuous wave Doppler echocardiography for noninvasive assessment of left Ventricular dP/dt and relaxation time constant from mitral regurgitant spectra in patients.
Journal of the American College of Cardiology, 1994Co-Authors: Chunguang Chen, L. Leonardo Rodriguez, Jean Paul Lethor, Robert A. Levine, Marc S. Semigran, Michael A. Fifer, Arthur E. Weyman, James D. ThomasAbstract:Objectives. We previously demonstrated experimentally that the mitral regurgitant velocity spectrum can be used to estimate left Ventricular Pressure throughout systole and may provide a new noninvasive method for estimating maximal dP/dt and the relaxation time constant. This study was designed to test this method in patients. Background. The maximal first derivative of left Ventricular Pressure (dP/dt) and the time constant of left Ventricular isovolumetric relaxation (τ) are important variables of left Ventricular function, but the need for invasive measurement with high fidelity catheters has limited their use in clinical cardiology. Methods. Twelve patients with mitral regurgitation were studied. The Doppler mitral regurgitant velocity spectrum was recorded simultaneously with micromanometer left Ventricular Pressure tracings in all patients. The regurgitant velocity profiles were digitized and converted to ventriculoatrial (VA) Pressure gradient curves using the simplified Bernoulli equation and differentiated into instantaneous dP/dt. The relaxation time constant (τ) was calculated assuming a zero Pressure asymptote from catheter left Ventricular Pressure decay (τc) and forn the Dopplerderived VA gradient curve with corrections. Two methods were used to correct the Doppler gradient curve to better approximate the left Ventricular Pressure decay before calculating the relaxation time constant: 1) adding an arbitrary 10 mm Hg (τ10), and 2) adding the actual mean pulmonary capillary Pressure (τla). Results. The Doppler-derived maximal positive dP/dt (1,394 ± 302 mm Hg/s [mean ± SD]) correlated well (r = 0.91) with the catheter-derived maximal dP/dt (1,449 ± 307 mm Hg/s). Although the Doppler-derived negative maximal dP/dt differed slightly from catheter measurement (1,014 ± 289 vs. 1,195 ± 354 mm Hg/s, p < 0.01), the correlation between Doppler and catheter measurements was similarly good (r = 0.89, p < 0.0001). The correlation between τ10and τcwas excellent (r = 0.93, p < 0.01), but the Doppler-derived τ10(50.0 ± 11.0 ms) slightly underestimated the catheter-derived τc(55.5 ± 12.8 ms, p < 0.01). This slight underestimation could be corrected by adding the actual pulmonary capillary wedge Pressure to the Doppler gradient curve. Conclusions. Doppler echocardiography provides an accurate and reliable method for estimating left Ventricular maximal positive dP/dt, maximal negative dP/dt and the relaxation time constant (τ) in patients with mitral regurgitation.
Jan Baan - One of the best experts on this subject based on the ideXlab platform.
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effects of acute left Ventricular unloading on right Ventricular function in normal and chronic right Ventricular Pressure overloaded lambs
The Journal of Thoracic and Cardiovascular Surgery, 2003Co-Authors: Boudewijn P J Leeuwenburgh, Paul Steendijk, Willem A Helbing, Paul H Schoof, Jan BaanAbstract:Abstract Objective: Right Ventricular Pressure overload occurs in several types of (congenital) heart disease, as well as in pulmonary disease. Clinical outcome in some of these patient groups might in part be related to left Ventricular loading conditions. The effects of left Ventricular unloading on the function of the hypertrophic right ventricle have not been studied. We aimed to study the effects of left Ventricular unloading on right Ventricular hemodynamics and contractility in an animal model of chronic right Ventricular Pressure overload. Methods: In lambs the pulmonary artery was chronically banded to increase right Ventricular Pressure to systemic levels. After 8 weeks, right Ventricular contractility and hemodynamic function were assessed in these lambs, as well as in age-matched control animals, by using a combined Pressure-conductance catheter in the right ventricle during baseline conditions and during complete bypass of the left ventricle. Results: In both groups acute left Ventricular unloading significantly decreased left Ventricular Pressure to low levels while aortic Pressure was maintained. In the right ventricle of the control group, both end-systolic and end-diastolic volumes increased with left Ventricular unloading ( P Conclusions: Both in normal hearts and in hearts subject to chronic right Ventricular Pressure overload, acute left Ventricular unloading decreases right Ventricular contractility. Although no effects on cardiac output are encountered in normal hearts during left Ventricular bypass, cardiac output is improved in right Ventricular Pressure-overloaded hearts, most likely related to improved right Ventricular diastolic compliance. J Thorac Cardiovasc Surg 2003;125:481-90
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cardiovascular mr imaging Pressure gating using the arterial Pressure signal from a conventional ferromagnetic micromanometer tip catheter
Magnetic Resonance Imaging, 1994Co-Authors: Peter M T Pattynama, Enno T Van Der Velde, Hildo J Lamb, Jan Baan, Paul Steendijk, Albert De RoosAbstract:Abstract We used the arterial Pressure wave as a reliable trigger to synchronize MR imaging to the cardiac cycle. Pressure readings and MR images remained undistorted using a conventional ferromagnetic micromanometer-tip catheter. As a safe alternative to triggering to Ventricular Pressure, this approach allows varying the time relation between the trigger and the cardiac cycle while maintaining the advantages of Pressure-gating.
Philip J Kilner - One of the best experts on this subject based on the ideXlab platform.
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increased airway Pressure and simulated branch pulmonary artery stenosis increase pulmonary regurgitation after repair of tetralogy of fallot real time analysis with a conductance catheter technique
Circulation, 1997Co-Authors: Rajiv Chaturvedi, Philip J Kilner, Paul A White, Andrew Bishop, Richard Szwarc, A N RedingtonAbstract:Background Pulmonary regurgitation (PR) is an important determinant of outcome after repair of tetralogy of Fallot. Baseline PR was measured by magnetic resonance (MR) phase velocity mapping and from real-time right Ventricular Pressure-volume loops with a conductance catheter. Subsequently, the impact of two loading maneuvers (increased airway Pressure, simulated branch pulmonary artery stenosis) on PR was assessed by the conductance catheter method. Methods and Results Thirteen patients, 3 to 35 years after tetralogy of Fallot repair or pulmonary valvotomy, had PR measured by MR phase velocity mapping while breathing spontaneously. During catheterization under general anesthesia, PR was estimated from right Ventricular Pressure-volume loops generated by conductance and microtip Pressure catheters. The effect of increased airway Pressure (continuous positive airway Pressure, 20 cm H2O; n=12) and simulated branch pulmonary artery stenosis (transient balloon occlusion of a branch pulmonary artery, n=7) was...
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increased airway Pressure and simulated branch pulmonary artery stenosis increase pulmonary regurgitation after repair of tetralogy of fallot real time analysis with a conductance catheter technique
Circulation, 1997Co-Authors: Rajiv R Chaturvedi, Philip J Kilner, Paul A White, Andrew Bishop, Richard Szwarc, A N RedingtonAbstract:BACKGROUND: Pulmonary regurgitation (PR) is an important determinant of outcome after repair of tetralogy of Fallot. Baseline PR was measured by magnetic resonance (MR) phase velocity mapping and from real-time right Ventricular Pressure-volume loops with a conductance catheter. Subsequently, the impact of two loading maneuvers (increased airway Pressure, simulated branch pulmonary artery stenosis) on PR was assessed by the conductance catheter method. METHODS AND RESULTS: Thirteen patients, 3 to 35 years after tetralogy of Fallot repair or pulmonary valvotomy, had PR measured by MR phase velocity mapping while breathing spontaneously. During catheterization under general anesthesia. PR was estimated from right Ventricular Pressure-volume loops generated by conductance and microtip Pressure catheters. The effect of increased airway Pressure (continuous positive airway Pressure, 20 cm H2O; n = 12) and simulated branch pulmonary artery stenosis (transient balloon occlusion of a branch pulmonary artery, n = 7) was measured. Basal PR fraction derived by MR and from right Ventricular Pressure-volume loops had a correlation coefficient of .76 and mean of differences of 2.0 +/- 18.2% (95% limits of agreement). Increased airway Pressure increased PR (16.3 +/- 11.4% to 25.7 +/- 17.3%, P < .01). Simulated branch pulmonary artery stenosis increased right Ventricular end-systolic Pressure (69.1 +/- 21.4 to 78.7 +/- 23.1 mm Hg, P < .05) and PR (27.5 +/- 11.3% to 36.9 +/- 12.8%, P < .05). CONCLUSIONS: There was reasonable agreement between MR phase velocity-derived PR fraction and that obtained from right Ventricular Pressure-volume loops generated by use of conductance and Pressure-microtip catheters. Exacerbation of PR by increased airway Pressure and branch pulmonary stenosis may be relevant to the acute postoperative and long-term management, respectively, of patients after repair of tetralogy of Fallot.
