The Experts below are selected from a list of 1620 Experts worldwide ranked by ideXlab platform
Hongyu Wang - One of the best experts on this subject based on the ideXlab platform.
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direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties
Circulation Research, 1995Co-Authors: Alan J. Bank, Spencer H Kubo, Jan Holte, Thomas J Dresing, Robert F. Wilson, Hongyu WangAbstract:Abstract The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using Intravascular Ultrasound. A 3.5F 30-MHz Intravascular Ultrasound Catheter was placed through a sheath into the brachial artery, and intra-arterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-...
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direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties
Circulation Research, 1995Co-Authors: Alan J. Bank, Spencer H Kubo, Jan Holte, Thomas J Dresing, Robert F. Wilson, Hongyu WangAbstract:The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using Intravascular Ultrasound. A 3.5F 30-MHz Intravascular Ultrasound Catheter was placed through a sheath into the brachial artery, and intraarterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-arterial nitroglycerin (100 micrograms) and norepinephrine (1.2 micrograms). A pressurized cuff surrounding the brachial artery was inflated to reduce transmural brachial artery pressure. Using this technique, we were able to measure the following arterial characteristics for the first time in human subjects in vivo: (1) the effective unstressed arterial radius and (2) the pressure-area, stress-strain, and pressure-Einc relations over a wide pressure range (0 to 100 mm Hg). Intra-arterial nitroglycerin increased brachial artery area by 22% and intraarterial norepinephrine decreased brachial artery area by 17% at 100 mm Hg transmural pressure (P < .001 versus baseline).(ABSTRACT TRUNCATED AT 250 WORDS)
Alan J. Bank - One of the best experts on this subject based on the ideXlab platform.
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direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties
Circulation Research, 1995Co-Authors: Alan J. Bank, Spencer H Kubo, Jan Holte, Thomas J Dresing, Robert F. Wilson, Hongyu WangAbstract:Abstract The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using Intravascular Ultrasound. A 3.5F 30-MHz Intravascular Ultrasound Catheter was placed through a sheath into the brachial artery, and intra-arterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-...
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direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties
Circulation Research, 1995Co-Authors: Alan J. Bank, Spencer H Kubo, Jan Holte, Thomas J Dresing, Robert F. Wilson, Hongyu WangAbstract:The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using Intravascular Ultrasound. A 3.5F 30-MHz Intravascular Ultrasound Catheter was placed through a sheath into the brachial artery, and intraarterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-arterial nitroglycerin (100 micrograms) and norepinephrine (1.2 micrograms). A pressurized cuff surrounding the brachial artery was inflated to reduce transmural brachial artery pressure. Using this technique, we were able to measure the following arterial characteristics for the first time in human subjects in vivo: (1) the effective unstressed arterial radius and (2) the pressure-area, stress-strain, and pressure-Einc relations over a wide pressure range (0 to 100 mm Hg). Intra-arterial nitroglycerin increased brachial artery area by 22% and intraarterial norepinephrine decreased brachial artery area by 17% at 100 mm Hg transmural pressure (P < .001 versus baseline).(ABSTRACT TRUNCATED AT 250 WORDS)
T Kohl - One of the best experts on this subject based on the ideXlab platform.
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multimodal fetal transesophageal echocardiography for fetal cardiac intervention in sheep
Circulation, 2001Co-Authors: T Kohl, Martin Westphal, Danja Strumper, Sarah Achenbach, Susan Halimeh, Philipp Petry, Sebastian Aryee, Tim Buller, Rasa Aleksiene, Boulos AsfourAbstract:Background The overall performance of available mechanical Intravascular Ultrasound Catheters for fetal transesophageal echocardiography during fetoscopic fetal cardiac interventions in sheep has been limited by radioelectronic interference, low system frame rates, and low acoustic outputs. Therefore, a more reliable device is desired for human fetoscopic surgical procedures. Methods and Results We assessed the potential of a newly available 10-French phased-array Intravascular Ultrasound Catheter for multimodal fetal transesophageal echocardiography in 5 fetal sheep between 78 and 98 days of gestation (term, 145 to 150 d). The Intravascular Ultrasound Catheter was easily inserted through the mouth into the esophagus in all 5 sheep fetuses (mean weight, 600 g), and it permitted high-quality 2D imaging of the fetal heart in vertical imaging planes that were validated by MRI. Color Doppler and pulsed Doppler imaging permitted clear assessment of fetal cardiovascular flows and recording of velocity-time inte...
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fetal transesophageal echocardiography utilizing a 10 f 10 mhz Intravascular Ultrasound Catheter comparison with conventional maternal transabdominal fetal echocardiography in sheep
Ultrasound in Medicine and Biology, 1999Co-Authors: T Kohl, Kenji Suda, Julia Reckers, Hans H Scheld, J Vogt, Norman H. SilvermanAbstract:The purpose of our study in fetal sheep was to assess the measurement agreement between fetal transesophageal echocardiography (FTEE) and conventional maternal transabdominal echocardiography (CMTFE) by the Bland-Altman method. We performed our study in 11 fetal sheep between 95-103 days of gestation (term = 145 days). FTEE was performed by imaging the fetal heart in horizontal planes utilizing a 10-F, 10-MHz Intravascular Ultrasound Catheter. CMTFE was carried out using a 5.0-MHz phased-array transducer replicating the FTEE imaging planes. We found close agreement between FTEE and CMTFE measurements of great vessel and cardiac valvar dimensions. Conversely, the variability between both techniques for measuring ventricular dimensions was inadequate. We conclude that FTEE permits measurement of great vessel and cardiac valve dimensions with high agreement with CMTFE measurements. This finding strengthens the applicability of FTEE as a monitoring tool during experimental open or fetoscopic fetal cardiac interventions.
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fetoscopic and open transumbilical fetal cardiac Catheterization in sheep potential approaches for human fetal cardiac intervention
Circulation, 1997Co-Authors: T Kohl, Michael R. Harrison, Norman H. Silverman, Zoltan Szabo, Kenji Suda, Edwin Petrossian, Deniz Kececioglu, Philip Moore, Tony M Chou, Frank L HanleyAbstract:Background Shortening the prenatal disease course of severe aortic and pulmonary stenoses by balloon valvuloplasty may diminish their postnatal expression. The purpose of this study in fetal sheep was to assess the feasibility of fetoscopic and open transumbilical fetal cardiac Catheterization guided by fetal transesophageal echocardiography to provide alternative approaches for human fetal cardiac intervention. Methods and Results We studied a total of nine fetal sheep (95 to 103 days of gestation; term=145 to 150 days) and performed transumbilical fetal cardiac Catheterization by a minimally invasive fetoscopic (n=6) or an open fetal surgical approach (n=3). Monitored by fetal transesophageal echocardiography, with an 8F or 10F, 10-MHz Intravascular Ultrasound Catheter we placed guidewires and interventional Catheters via the umbilical arterial route into the fetal heart. In three of the fetuses, we created supravalvar pulmonary artery stenosis by open fetal cardiac surgery. After fetal and maternal recovery, we exteriorized these fetuses and performed open transumbilical fetal cardiac Catheterization with successful pulmonary arterial angioplasty in two. Three fetuses survived fetoscopic transumbilical Catheterization for 1 or 2 days and died most likely of blood loss after sheath dislodgment (n=1) or removal (n=2). By securing the sheath insertion site with a suture, we prevented sheath dislodgment and minimized bleeding during sheath removal in three fetuses. These fetuses then survived fetoscopic transumbilical fetal cardiac Catheterization for 1 to 2 weeks before being killed. Conclusions This study in fetal sheep demonstrates that fetoscopic and open transumbilical fetal cardiac Catheterization are feasible and, guided by fetal transesophageal echocardiography, provide potential alternative approaches for human fetal cardiac intervention.
Jan Holte - One of the best experts on this subject based on the ideXlab platform.
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direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties
Circulation Research, 1995Co-Authors: Alan J. Bank, Spencer H Kubo, Jan Holte, Thomas J Dresing, Robert F. Wilson, Hongyu WangAbstract:Abstract The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using Intravascular Ultrasound. A 3.5F 30-MHz Intravascular Ultrasound Catheter was placed through a sheath into the brachial artery, and intra-arterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-...
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direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties
Circulation Research, 1995Co-Authors: Alan J. Bank, Spencer H Kubo, Jan Holte, Thomas J Dresing, Robert F. Wilson, Hongyu WangAbstract:The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using Intravascular Ultrasound. A 3.5F 30-MHz Intravascular Ultrasound Catheter was placed through a sheath into the brachial artery, and intraarterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-arterial nitroglycerin (100 micrograms) and norepinephrine (1.2 micrograms). A pressurized cuff surrounding the brachial artery was inflated to reduce transmural brachial artery pressure. Using this technique, we were able to measure the following arterial characteristics for the first time in human subjects in vivo: (1) the effective unstressed arterial radius and (2) the pressure-area, stress-strain, and pressure-Einc relations over a wide pressure range (0 to 100 mm Hg). Intra-arterial nitroglycerin increased brachial artery area by 22% and intraarterial norepinephrine decreased brachial artery area by 17% at 100 mm Hg transmural pressure (P < .001 versus baseline).(ABSTRACT TRUNCATED AT 250 WORDS)
Robert F. Wilson - One of the best experts on this subject based on the ideXlab platform.
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direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties
Circulation Research, 1995Co-Authors: Alan J. Bank, Spencer H Kubo, Jan Holte, Thomas J Dresing, Robert F. Wilson, Hongyu WangAbstract:Abstract The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using Intravascular Ultrasound. A 3.5F 30-MHz Intravascular Ultrasound Catheter was placed through a sheath into the brachial artery, and intra-arterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-...
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direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties
Circulation Research, 1995Co-Authors: Alan J. Bank, Spencer H Kubo, Jan Holte, Thomas J Dresing, Robert F. Wilson, Hongyu WangAbstract:The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using Intravascular Ultrasound. A 3.5F 30-MHz Intravascular Ultrasound Catheter was placed through a sheath into the brachial artery, and intraarterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-arterial nitroglycerin (100 micrograms) and norepinephrine (1.2 micrograms). A pressurized cuff surrounding the brachial artery was inflated to reduce transmural brachial artery pressure. Using this technique, we were able to measure the following arterial characteristics for the first time in human subjects in vivo: (1) the effective unstressed arterial radius and (2) the pressure-area, stress-strain, and pressure-Einc relations over a wide pressure range (0 to 100 mm Hg). Intra-arterial nitroglycerin increased brachial artery area by 22% and intraarterial norepinephrine decreased brachial artery area by 17% at 100 mm Hg transmural pressure (P < .001 versus baseline).(ABSTRACT TRUNCATED AT 250 WORDS)