In Vitro and finite-element model investigation of the conductance technique for measurement of aortic segmental volume

Hettrick, Douglas A.; Battocletti, Joseph H.; Ackmann, James J.; Linehan, J. H.; Warltier, David C.

doi:10.1007/bf02684180

Cited by 15 publications

(19 citation statements)

References 15 publications

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“…The blood vessel length downstream of stenosis was shown to be sufficient for the largest recirculation bubble observed in the flow conditions studied. The computa-tional domain in the radial direction including blood vessel lumen and surrounding tissue is similar to previous conductance catheter studies (9,15). Governing equations and numerical methods.…”

Section: Methodsmentioning

confidence: 94%

Conductance catheter measurements of lumen area of stenotic coronary arteries: theory and experiment

Choi

Farren

Zhang

et al. 2011

Journal of Applied Physiology

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GS. Conductance catheter measurements of lumen area of stenotic coronary arteries: theory and experiment. J Appl Physiol 111: 758 -765, 2011. First published June 16, 2011 doi:10.1152/japplphysiol.00304.2011.-An injection of saline solution is required for the measurement of vessel lumen area using a conductance catheter. The injection of room temperature saline to displace blood in a vessel inevitably involves mass and heat transport and electric field conductance. The objective of the present study is to understand the accuracy of conductance method based on the phenomena associated with the saline injection into a stenotic blood vessel. Computational fluid dynamics were performed to simulate flow and its relation to transport and electric field in a stenotic artery for two different sized conductance catheters (0.9 and 0.35 mm diameter) over a range of occlusions [56 -84% cross-sectional area (CSA) stenosis]. The results suggest that the performance of conductance catheter is dependent on catheter size and severity of stenosis more significantly for 0.9 mm than for 0.35 mm catheter. Specifically, the time of detection of 95% of injected saline solution at the detection electrodes was shown to range from 0.67 to 3.7 s and 0.82 to 0.94 s for 0.9 mm and 0.35 mm catheter, respectively. The results also suggest that the detection electrodes of conductance catheter should be placed outside of flow recirculation region distal to the stenosis to minimize the detection time. Finally, the simulations show that the accuracy in distal CSA measurements, however, is not significantly altered by whether the position of detection electrodes is inside or outside of recirculation zone (error was within 12% regardless of detection electrodes position). The results were experimentally validated for one lesion geometry and the simulation results are within 8% of actual measurements. The simulation of conductance catheter injection method may lead to further optimization of device and method for accurate sizing of diseased coronary arteries, which has clinical relevance to percutaneous intervention. stenosis; impedance catheter; saline injection; dynamic electrical conductivity; transport ACCURATE MEASUREMENT OF LUMEN cross-sectional area (CSA) of coronary arteries is clinically important for balloon angioplasty and stenting. The image-based methods such as quantitative coronary angiography (QCA), computed tomography (CT), and intravascular ultrasound (IVUS) have been used for vessel sizing. Angiographic assessment is limited by the spatial resolution while IVUS is limited by the variability in interpretation of images, added time, and cost. A nonimaging conductance catheter based on the principle of physics has been introduced for fast, accurate, and real-time measurement of coronary and peripheral vessels (7,(15)(16)(17).The conductance catheters have been widely adopted to determine the chamber volume of ventricle (1,3,(12)(13)(14) and the CSA of aorta (8 -10) and medium size vessels, e.g., coronary, femoral and carotid (7, 15-...

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Section: Methodsmentioning

confidence: 94%

Conductance catheter measurements of lumen area of stenotic coronary arteries: theory and experiment

Choi

Farren

Zhang

et al. 2011

Journal of Applied Physiology

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“…It is agreed that the nonhomogeneity of the electric field is much less of a problem when applying the conductance technique in the aorta than in the left ventricle because the vessel more closely adheres to the cylindrical model (11). In blood vessels, Hettrick et al (12) showed that the value of ␣ is near unity for small cylinders (Ͻ10 mm in diameter) in a finite-element simulation and in in vitro measurements.…”

Section: Discussionmentioning

confidence: 99%

“…THE CONDUCTANCE CATHETER METHOD, which has been used previously to measure ventricular volume (4 -5, 7, 14 -16, 29, 30, 33), has recently been adapted to determine the crosssectional area (CSA) of the aorta (11)(12)(13). The conductance catheter technique is based on a cylindrical model by measuring the electrical impedance of the blood with two outer electrodes for excitation and two inner electrodes for detection to yield the CSA of the chamber of interest.…”

mentioning

confidence: 99%

Novel method for measurement of medium size arterial lumen area with an impedance catheter: in vivo validation

Kassab¹,

Lontis²,

Hørlyck³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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Gregersen. Novel method for measurement of medium size arterial lumen area with an impedance catheter: in vivo validation. Am J Physiol Heart Circ Physiol 288: H2014 -H2020, 2005; doi:10.1152/ ajpheart.00508.2004.-There is no doubt that the transformation of a cardiac catheter into a conductance catheter that allows reliable and accurate assessment of lumen cross-sectional area (CSA) will provide a powerful diagnostic and treatment tool for the invasive cardiologist. The objective of this study was to develop a method based on the impedance catheter that allows accurate and reproducible measurements of CSA for medium size vessels (e.g., coronary, femoral, and carotid arteries). Two solutions of NaCl (0.5% and 1.5%) with known conductivities were injected directly into the lumen of the artery in eight swine. We showed that the CSA can be determined analytically from two Ohm's law-type algebraic equations that account for the parallel conductance of the current into the surrounding tissue. Excellent agreement was found between the conductance catheter with the proposed two-injection method and B-mode ultrasound (US). The root mean square error for the impedance measurements was 4.8% of the mean US diameter. The repeatability of the technique was assessed with duplicate measurements. The mean of the difference between the two measurements was nearly zero, and the repeatability coefficient was within 2.4% of the mean of the two measurements. The validated method was used to assess the degree of acute vasodilatation of the vessel in response to flow overload. carotid artery; femoral artery; coronary artery; conductance catheter; cylindrical model THE CONDUCTANCE CATHETER METHOD, which has been used previously to measure ventricular volume (4 -5, 7, 14 -16, 29, 30, 33), has recently been adapted to determine the crosssectional area (CSA) of the aorta (11-13). The conductance catheter technique is based on a cylindrical model by measuring the electrical impedance of the blood with two outer electrodes for excitation and two inner electrodes for detection to yield the CSA of the chamber of interest. Two major difficulties have hampered the routine use of the conductance catheter for measurement of absolute CSA or volume of the aorta or ventricle, respectively: 1) nonhomogeneity of the electric field and 2) leakage of current into the organ wall and surrounding tissue (parallel conductance). These two factors violate the assumptions that underlie the cylindrical model for the conductance method. The current approach to the problem is to include a slope correction term in the cylindrical model to account for the nonhomogeneity of the electric field and an offset error term to correct for the current "leakage" through the vessel wall and surrounding tissue.The nonuniformity in electric field is known to be very significant in the aorta under in vivo conditions (13), primarily because of the complex electrical properties of blood cells under dynamic flow conditions (6, 21-28, 31-32). The error due to parallel conductance i...

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“…The length of blood vessel segment (30 mm) was set to be sufficient to encompass the electric field by four electrodes of conductance catheter (0.9 mm diameter corresponding to 0.035 00 ). The computational domain in the radial direction, including blood vessel lumen and surrounding tissue, is more anatomically relevant, while the domain was assumed to be cylindrically axisymmetric in the previous conductance catheter studies [7,9,12].…”

Section: Geometry and Computational Domainmentioning

confidence: 99%

“…The conductance catheter has been widely adopted for sizing the chamber volume of ventricles [1 -5] and the luminal diameter of aorta [6,7] and medium-size arteries [8 -11]. Two bolus injections of saline solutions with known electrical conductivities (e.g.…”

Section: Introductionmentioning

confidence: 99%

Impact of surrounding tissue on conductance measurement of coronary and peripheral lumen area

Choi

Jansen

Zhang

et al. 2012

J. R. Soc. Interface.

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Parallel conductance (electric current flow through surrounding tissue) is an important determinant of accurate measurements of arterial lumen diameter, using the conductance method. The present study is focused on the role of non-uniform geometrical/electrical configurations of surrounding tissue, which are a primary source of electric current leakage. Computational models were constructed to simulate the conductance catheter measurement with two different excitation electrodes spacings (i.e. 12 and 20 mm for coronary and peripheral sizing, respectively) for different vessel -tissue configurations: (i) blood vessel fully embedded in muscle tissue, (ii) blood vessel superficially embedded in muscle tissue, and (iii) blood vessel superficially embedded in muscle tissue with fat covering half of the arterial vessel (anterior portion). The simulations suggest that the parallel conductance and accuracy of measurement is dependent on the inhomogeneous/anisotropic configuration of surrounding tissue, including the asymmetric dimension and anisotropy in electrical conductivity of surrounding tissue. Specifically, the measurement was shown to be accurate as long as the vessel was superficial, regardless of the considerable total surrounding tissue dimension for coronary or peripheral arteries. Moreover, it was shown that the unfavourable impact of parallel conductance on the accuracy of conductance catheter measurement is decreased by the combination of a lower transverse electrical conductivity of surrounding muscle tissue, a smaller electrode spacing and a larger lumen diameter. The present findings confirm that the conductance catheter technique provides an accurate platform for sizing of clinically relevant (i.e. superficial and diseased) arteries.

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In Vitro and finite-element model investigation of the conductance technique for measurement of aortic segmental volume

Cited by 15 publications

References 15 publications

Conductance catheter measurements of lumen area of stenotic coronary arteries: theory and experiment

Conductance catheter measurements of lumen area of stenotic coronary arteries: theory and experiment

Novel method for measurement of medium size arterial lumen area with an impedance catheter: in vivo validation

Impact of surrounding tissue on conductance measurement of coronary and peripheral lumen area

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