Implications of complex anatomical junctions on conductance catheter measurements of coronary arteries

2013 ◽  
Vol 114 (5) ◽  
pp. 656-664 ◽  
Author(s):  
Hyo Won Choi ◽  
Zhen-Du Zhang ◽  
Neil D. Farren ◽  
Ghassan S. Kassab
Keyword(s):  
Measurement Accuracy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Conductance Catheter ◽  
Cross Sectional ◽  
In Vivo Experiments ◽  
Conductance Method ◽  
Vessel Curvature

In vivo, the position of the conductance catheter to measure vessel lumen cross-sectional area may vary depending on where the conductance catheter is deployed in the complex anatomical geometry of arteries, including branches, bifurcations, or curvatures. The objective here is to determine how such geometric variations affect the cross-sectional area (CSA) estimates obtained using the cylindrical model. Computer simulations and in vitro and in vivo experiments were used to assess how the electric field and associated CSA measurement accuracy are affected by three typical in vivo conditions: 1) a vessel with abrupt change in lumen diameter (e.g., transition from aorta to coronary ostia); 2) a vessel with a T-bifurcation or a Y-bifurcation; and 3) a vessel curvature, such as in the right coronary artery, aorta, or pulmonary artery. The error in diameter from simulation results was shown to be relatively small (<7%), unless the detection electrodes were placed near the junction between two different lumen diameters or at a bifurcation junction. Furthermore, the present findings show that the effect of misaligned catheter-vessel geometrical configuration and vessel curvature on measurement accuracy is negligible. Collectively, the findings support the accuracy of the conductance method for sizing blood vessels, despite the geometric complexities of the cardiovascular system, as long as the detection electrodes are not placed at a large discontinuity in diameter or at bifurcation junctions.

scholarly journals Rectus Femoris Mimicking Ultrasound Phantom for Muscle Mass Assessment: Design, Research, and Training Application

2021 ◽  
Vol 10 (12) ◽  
pp. 2721
Author(s):  
Nobuto Nakanishi ◽  
Shigeaki Inoue ◽  
Rie Tsutsumi ◽  
Yusuke Akimoto ◽  
Yuko Ono ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Rectus Femoris ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Phantom Model ◽  
Ultrasound Measurements ◽  
Ultrasound Phantom

Ultrasound has become widely used as a means to measure the rectus femoris muscle in the acute and chronic phases of critical illness. Despite its noninvasiveness and accessibility, its accuracy highly depends on the skills of the technician. However, few ultrasound phantoms for the confirmation of its accuracy or to improve technical skills exist. In this study, the authors created a novel phantom model and used it for investigating the accuracy of measurements and for training. Study 1 investigated how various conditions affect ultrasound measurements such as thickness, cross-sectional area, and echogenicity. Study 2 investigated if the phantom can be used for the training of various health care providers in vitro and in vivo. Study 1 showed that thickness, cross-sectional area, and echogenicity were affected by probe compression strength, probe angle, phantom compression, and varying equipment. Study 2 in vitro showed that using the phantom for training improved the accuracy of the measurements taken within the phantom, and Study 2 in vivo showed the phantom training had a short-term effect on improving the measurement accuracy in a human volunteer. The new ultrasound phantom model revealed that various conditions affected ultrasound measurements, and phantom training improved the measurement accuracy.

Influence of site of tracheal pressure measurement on in situ estimation of endotracheal tube resistance

1994 ◽  
Vol 77 (6) ◽  
pp. 2899-2906 ◽  
Author(s):  
P. Navalesi ◽  
P. Hernandez ◽  
D. Laporta ◽  
J. S. Landry ◽  
F. Maltais ◽  
...  
Keyword(s):  
Endotracheal Tube ◽  
Fluid Dynamic ◽  
Reference Value ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Tracheal Pressure

In situ measurement of distal tracheal pressure (Ptr) via an intraluminal side-hole catheter (IC) has been used to determine endotracheal tube (Rett) and intrinsic patient (Rpt) resistances in intubated subjects. Because of differences in cross-sectional area between the endotracheal tube (ETT) and trachea, fluid dynamic principles predict that IC position should critically influence these results. Accordingly, the aim of this study was to determine the effect of IC position on Rett. Ptr was recorded in vitro through an IC from 2 cm inside, at the tip of, or 2 cm outside an ETT (7, 8, and 9 mm ID) situated within an artificial trachea (13, 18, and 22 mm ID). A reference value of Rett was also obtained. Results were unaffected by IC position during inspiration, overestimating Rett by 7.9 +/- 0.7% (SE). In contrast, during expiration, Rett fell as IC position changed from outside to inside the ETT and was underestimated by 41.3 +/- 3.6% with Ptr recorded inside the ETT. Varying ETT or tracheal size had little effect on the relative error in Rett. The IC itself did increase Rett due to a reduction in effective cross-sectional area, the change varying directly with IC size and inversely with ETT caliber. In vivo values in 11 intubated patients were comparable to in vitro results. In summary, IC position and size can have important consequences on in situ measurements of Ptr and should be considered when clinically monitoring Rett or Rpt.

scholarly journals Rectus Femoris Mmimicking Ultrasound Phantom for Muscle Mass Assessment: Design, Research, and Training Application

2021 ◽  
Author(s):  
Nobuto Nakanishi ◽  
Shigeaki Inoue ◽  
Rie Tsutsumi ◽  
Yusuke Akimoto ◽  
Yuko Ono ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Rectus Femoris ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Care Providers ◽  
Cross Sectional ◽  
Phantom Model ◽  
Ultrasound Measurements ◽  
Ultrasound Phantom

Ultrasound has become widely used as a mean to measure the rectus femoris muscle in the acute and chronic phase of critical illness. Despite its noninvasiveness and accessibility, its accuracy highly depends on the skills of the technician. However, few ultrasound phantoms for the confirmation of its accuracy or to improve technical skills exist. In this study, we created a novel phantom model and used it for investigating the accuracy of measurements and for training. Study 1 investigated how various conditions affect ultrasound measurements such as thickness, cross-sectional area, and echogenicity. Study 2 investigated if the phantom can be used for training of various health care providers in vitro and vivo. Study 1 showed that thickness, cross-sectional area, and echogenicity were affected by probe compression strength, probe angle, phantom compression, and varying equipment. Study 2 in vitro showed that using the phantom for training improved the accuracy of the measurements taken within phantom, and Study 2 in vivo showed the phantom training had a short-term effect on improving the measurement accuracy in a human volunteer. The new ultrasound phantom model revealed that various conditions affected ultrasound measurements, and phantom training improved the measurement accuracy.

A method of in-vitro measurement of the cross-sectional area of soft tissues, using ultrasonography

2002 ◽  
Vol 7 (2) ◽  
pp. 247-251 ◽  
Author(s):  
Masahiko Noguchi ◽  
Toshiya Kitaura ◽  
Kazuya Ikoma ◽  
Yoshiaki Kusaka
Keyword(s):  
Soft Tissues ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
The Cross

Role of superoxide anion in regulating pressor and vascular hypertrophic response to angiotensin II

2002 ◽  
Vol 282 (5) ◽  
pp. H1697-H1702 ◽  
Author(s):  
Hui Di Wang ◽  
Douglas G. Johns ◽  
Shanqin Xu ◽  
Richard A. Cohen
Keyword(s):  
Superoxide Anion ◽  
Pressor Response ◽  
Cross Sectional Area ◽  
Ang Ii ◽  
Sectional Area ◽  
Wild Type ◽  
Cross Sectional ◽  
Hypertrophic Response

Our purpose was to address the role of NAPDH oxidase-derived superoxide anion in the vascular response to ANG II. Blood pressure, aortic superoxide anion, 3-nitrotyrosine, and medial cross-sectional area were compared in wild-type mice and in mice that overexpress human superoxide dismutase (hSOD). The pressor response to ANG II was significantly less in hSOD mice. Superoxide anion levels were increased twofold in ANG II-treated wild-type mice but not in hSOD mice. 3-Nitrotyrosine increased in aortic endothelium and adventitia in wild-type but not hSOD mice. In contrast, aortic medial cross-sectional area increased 50% with ANG II in hSOD mice, comparable to wild-type mice. The lower pressor response to ANG II in the mice expressing hSOD is consistent with a pressor role of superoxide anion in wild-type mice, most likely because it reacts with nitric oxide. Despite preventing the increase in superoxide anion and 3-nitrotyrosine, the aortic hypertrophic response to ANG II in vivo was unaffected by hSOD.

Conservation of bronchiolar wall area during constriction and dilation of human airways

1997 ◽  
Vol 82 (3) ◽  
pp. 954-958 ◽  
Author(s):  
R. W. Mitchell ◽  
E. Rühlmann ◽  
H. Magnussen ◽  
N. M. Muñoz ◽  
A. R. Leff ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Contraction ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Wall Area ◽  
Total Cross Sectional Area ◽  
Human Airways ◽  
Contraction And Relaxation

Mitchell, R. W., E. Rühlmann, H. Magnussen, N. M. Muñoz, A. R. Leff, and K. F. Rabe. Conservation of bronchiolar wall area during constriction and dilation of human airways. J. Appl. Physiol. 82(3): 954–958, 1997.—We assessed the effect of smooth muscle contraction and relaxation on airway lumen subtended by the internal perimeter ( A i) and total cross-sectional area ( A o) of human bronchial explants in the absence of the potential lung tethering forces of alveolar tissue to test the hypothesis that bronchoconstriction results in a comparable change of A iand A o. Luminal area (i.e., A i) and A owere measured by using computerized videomicrometry, and bronchial wall area was calculated accordingly. Images on videotape were captured; areas were outlined, and data were expressed as internal pixel number by using imaging software. Bronchial rings were dissected in 1.0- to 1.5-mm sections from macroscopically unaffected areas of lungs from patients undergoing resection for carcinoma, placed in microplate wells containing buffered saline, and allowed to equilibrate for 1 h. Baseline, A o[5.21 ± 0.354 (SE) mm2], and A i(0.604 ± 0.057 mm2) were measured before contraction of the airway smooth muscle (ASM) with carbachol. Mean A inarrowed by 0.257 ± 0.052 mm2in response to 10 μM carbachol ( P = 0.001 vs. baseline). Similarly, A onarrowed by 0.272 ± 0.110 mm2in response to carbachol ( P = 0.038 vs. baseline; P = 0.849 vs. change in A i). Similar parallel changes in cross-sectional area for A iand A owere observed for relaxation of ASM from inherent tone of other bronchial rings in response to 10 μM isoproterenol. We demonstrate a unique characteristic of human ASM; i.e., both luminal and total cross-sectional area of human airways change similarly on contraction and relaxation in vitro, resulting in a conservation of bronchiolar wall area with bronchoconstriction and dilation.

Muscle fiber number in biceps brachii in bodybuilders and control subjects

1984 ◽  
Vol 57 (5) ◽  
pp. 1399-1403 ◽  
Author(s):  
J. D. MacDougall ◽  
D. G. Sale ◽  
S. E. Alway ◽  
J. R. Sutton
Keyword(s):  
Muscle Fiber ◽  
Biceps Brachii ◽  
Cross Sectional Area ◽  
Muscle Size ◽  
Sectional Area ◽  
Cross Sectional ◽  
Trained Subjects ◽  
Fiber Area ◽  
Muscle Cross Sectional Area

Muscle fiber numbers were estimated in vivo in biceps brachii in 5 elite male bodybuilders, 7 intermediate caliber bodybuilders, and 13 age-matched controls. Mean fiber area and collagen volume density were calculated from needle biopsies and muscle cross-sectional area by computerized tomographic scanning. Contralateral measurements in a subsample of seven subjects indicated the method for estimation of fiber numbers to have adequate reliability. There was a wide interindividual range for fiber numbers in biceps (172,085–418,884), but despite large differences in muscle size both bodybuilder groups possessed the same number of muscle fibers as the group of untrained controls. Although there was a high correlation between average cross-sectional fiber area and total muscle cross-sectional area within each group, many of the subjects with the largest muscles also tended to have a large number of fibers. Since there were equally well-trained subjects with fewer than normal fiber numbers, we interpret this finding to be due to genetic endowment rather than to training-induced hyperplasia. The proportion of muscle comprised of connective and other noncontractile tissue was the same for all subjects (approximately 13%), thus indicating greater absolute amounts of connective tissue in the trained subjects. We conclude that in humans, heavy resistance training directed toward achieving maximum size in skeletal muscle does not result in an increase in fiber numbers.

scholarly journals Role of TRPC1 channel in skeletal muscle function

2010 ◽  
Vol 298 (1) ◽  
pp. C149-C162 ◽  
Author(s):  
Nadège Zanou ◽  
Georges Shapovalov ◽  
Magali Louis ◽  
Nicolas Tajeddine ◽  
Chiara Gallo ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Function ◽  
Transient Receptor Potential ◽  
Force Production ◽  
Receptor Potential ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Skeletal Muscle Function ◽  
Cross Sectional

Skeletal muscle contraction is reputed not to depend on extracellular Ca2+. Indeed, stricto sensu , excitation-contraction coupling does not necessitate entry of Ca2+. However, we previously observed that, during sustained activity (repeated contractions), entry of Ca2+is needed to maintain force production. In the present study, we evaluated the possible involvement of the canonical transient receptor potential (TRPC)1 ion channel in this entry of Ca2+and investigated its possible role in muscle function. Patch-clamp experiments reveal the presence of a small-conductance channel (13 pS) that is completely lost in adult fibers from TRPC1−/−mice. The influx of Ca2+through TRPC1 channels represents a minor part of the entry of Ca2+into muscle fibers at rest, and the activity of the channel is not store dependent. The lack of TRPC1 does not affect intracellular Ca2+concentration ([Ca2+]i) transients reached during a single isometric contraction. However, the involvement of TRPC1-related Ca2+entry is clearly emphasized in muscle fatigue. Indeed, muscles from TRPC1−/−mice stimulated repeatedly progressively display lower [Ca2+]itransients than those observed in TRPC1+/+fibers, and they also present an accentuated progressive loss of force. Interestingly, muscles from TRPC1−/−mice display a smaller fiber cross-sectional area, generate less force per cross-sectional area, and contain less myofibrillar proteins than their controls. They do not present other signs of myopathy. In agreement with in vitro experiments, TRPC1−/−mice present an important decrease of endurance of physical activity. We conclude that TRPC1 ion channels modulate the entry of Ca2+during repeated contractions and help muscles to maintain their force during sustained repeated contractions.

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