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Hemodynamic Information (hemodynamic + information)
Selected AbstractsPulmonary Venous Wedge Pressure Provides an Accurate Assessment of Pulmonary Artery Pressure in Children with a Bidirectional Glenn ShuntJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2003DANIEL H. GRUENSTEIN M.D. Purpose: In circulations with pulsatile pulmonary artery flow the pulmonary venous wedge pressure (PVWp) has been validated as a good estimate of pulmonary artery pressure (PAp), when PAp is low. The purpose of this study was to validate PVWp estimates of PAp in the less-pulsatile pulmonary circulation of children after bidirectional Glenn shunts. Methods: A retrospective study was performed of 22 simultaneous measurements of PVWp and PAp made during 20 catheterizations in 19 children who had undergone bidirectional Glenn procedures. The PAp was measured directly from the branch PA ipsilateral to the side of the PVWp, or in the SVC. Pulmonary resistance (Rp) was calculated with both PAp and PVWp, to assess the impact of PAp estimates on Rp determinations. Results: Patients ranged in age from 5 months to 10.7 years. There were a variety of univentricular cardiac malformations in the study group. Two children had antegrade pulmonary blood flow in addition to a bidirectional Glenn shunt. The mean PAp ranged from 4 to 14 mmHg, while mean PVWp ranged from 3 to 15 mmHg. Mean PVWp never differed from mean PAp by more than 3 mmHg. There was a significant linear relation between mean PAp and PVWp: PAp = 0.86 (PVWp) + 2.0 (R2= 0.89; P < 0.0001). PVWp provided a good approximation of PAp regardless of the presence (n = 2) or absence (n = 19) of antegrade pulmonary flow. There was a good linear correlation between the Rp calculated by both methods (RpPAp = 0.9 (RpVWp) + 0.5; R2= 0.74; P < 0.0001). Conclusion: The mean PVWp provides a close approximation of mean PAp in children with a bidirectional Glenn shunt and provides valuable hemodynamic information in cases where direct PAp measurements are unavailable. (J Interven Cardiol 2003;16:367,370) [source] Real-time Fourier velocity encoding: An in vivo evaluationJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2005Christopher K. Macgowan PhD Abstract Purpose To compare in vivo real-time Fourier velocity encoding (FVE), spectral-Doppler ultrasound, and phase-contrast (PC) magnetic-resonance (MR) imaging. Materials and Methods In vivo velocity spectra were measured in the suprarenal and infrarenal aorta and the hepatic segment of the inferior vena cava of eight normal volunteers using FVE, and compared to similar measurements using Doppler ultrasound and gated PC MR imaging. In vivo waveforms were compared qualitatively according to flow pattern appearance (number, shape, and position of velocity peaks) and quantitatively according to peak velocity. Results Good agreement was obtained between peak velocities measured in vitro using FVE and PC MR imaging (R2 = 0.99, P = 2.10,6, slope = 0.97 ± 0.05). Qualitatively, the FVE and ultrasound measurements agreed closely in the majority of in vivo cases (excellent or good in 21/24 cases) while the PC MR method resolved fewer velocity peaks due to the inherent temporal averaging of cardiac-gated studies (excellent or good agreement with FVE in 13/24 cases). Quantitatively, the FVE measurement of peak velocity correlated strongly with both ultrasound (R2 = 0.71, P = 2.10,7, slope = 0.81 ± 0.08) and PC MR (R2 = 0.85, P = 2.10,10, slope = 1.04 ± 0.08). Conclusion Real-time MR assessment of blood-flow velocity correlated well with spectral Doppler ultrasound. Such new methods may allow hemodynamic information to be acquired in vessels inaccessible to ultrasound or in patients for whom respiratory compensation is not possible. J. Magn. Reson. Imaging 2005;21:297,304. © 2005 Wiley-Liss, Inc. [source] Ophthalmic Artery Flow Direction on Color Flow Duplex Imaging Is Highly Specific for Severe Carotid StenosisJOURNAL OF NEUROIMAGING, Issue 1 2002Patrick S. Reynolds MD Background/Purpose. Collateral flow patterns are important risk factors for brain ischemia in the presence of internal carotid artery (ICA) stenosis or occlusion. Ophthalmic artery (OA) flow reversal, routinely studied by transcranial Doppler sonography, is an important marker for high-grade ICA stenosis or occlusion. The authors sought to define the value of assessing OA flow direction with color flow duplex ultrasonography (CDUS) in the setting of significant ICA disease. Methods. Of all patients having routine carotid ultrasound in the neurosonology laboratory between July 1995 and November 2000, 152 had both carotid and orbital (OA flow direction by reduced power orbital CDUS) examinations as well as angiographic confirmation of stenosis to which North American Symptomatic Carotid Endarterectomy Trial criteria could be applied. Degree of angiographic stenosis in these 152 patients (304 arteries) was correlated with OA flow direction. Results. Of 304 arteries, 101 had greater than 80% stenosis by angiogram. In 56 of these 101 arteries with high-grade stenosis or occlusion, the ipsilateral OA was reversed; however, OA flow direction was never reversed ipsilateral to arteries with less than 80% stenosis (sensitivity 55%, specificity 100%, negative predictive value 82%, and positive predictive value 100% for OA flow reversal as a marker of high-grade carotid lesions). Discussion/Conclusions. OA flow direction is easily studied with CDUS. Reversed OA flow direction is highly specific (100%) for severe ipsilateral ICA stenosis or occlusion, with excellent positive predictive value, moderate negative predictive value, and limited sensitivity. OA flow reversal is not only quite specific for severe ICA disease, which may be helpful if the carotid CDUS is difficult or inadequate, but may also provide additional hemodynamic insights (ie, the inadequacy of other collateral channels such as the anterior communicating artery). OA evaluation can provide important hemodynamic information and should be included as part of carotid CDUS if there is any evidence of ICA stenosis or occlusion. [source] Numerical Simulation of Hemodynamic Changes During Beating-heart Surgery: Analysis of the Effects of Cardiac Position Alteration in an Animal ModelARTIFICIAL ORGANS, Issue 1 2007Gianfranco Ferrari Abstract:, Hemodynamic instability, mostly due to vertical lifting of the heart, is usually observed during beating-heart surgical procedures. However, some hemodynamic parameters, such as coronary blood flow, are not routinely measured. A digital computer model of the circulation able to simulate and analyze the effects of heart lifting and the Trendelenburg maneuver, and thus supply detailed hemodynamic information to the clinicians would provide a useful analytical tool. A lumped parameters model of the circulation was applied to both ,-blocked and not ,-blocked pigs. The results confirmed a drop of cardiac output and coronary flow during heart lifting and a rise of both variables after the Trendelenburg maneuver for ,-blocked animals. In not ,-blocked pigs, the analysis was more complex but the model reproduced experimental data and permitted coronary flow to be estimated. These results showed the feasibility of numerical simulation for specific circulatory conditions encountered during beating-heart surgery. [source] | ||||||||||