Accuracy of the conductance catheter for measurement of ventricular volumes seen clinically: effects of electric field homogeneity and parallel conductance

1997 ◽  
Vol 44 (4) ◽  
pp. 266-277 ◽  
Author(s):  
C.C. Wu ◽  
T.C. Skalak ◽  
T.R. Schwenk ◽  
C.M. Mahler ◽  
A. Anne ◽  
...  
Keyword(s):  
Electric Field ◽  
Conductance Catheter ◽  
Ventricular Volumes ◽  
Field Homogeneity ◽  
Parallel Conductance ◽  
Electric Field Homogeneity

Simple circuit to improve electric field homogeneity in contour-clamped homogeneous electric field chambers

2003 ◽  
Vol 24 (78) ◽  
pp. 1137-1144
Author(s):  
José A. Herrera ◽  
Carlos A. Canino ◽  
Lilia López-Cánovas ◽  
Regnar Gigato ◽  
Ana Maria Riverón
Keyword(s):  
Electric Field ◽  
Simple Circuit ◽  
Homogeneous Electric Field ◽  
Field Homogeneity ◽  
Electric Field Homogeneity

Synthesis of Electrode Configurations that Conserve Fringing Electric Field Homogeneity in Euler Terms

2018 ◽  
Vol 63 (4) ◽  
pp. 593-597 ◽  
Author(s):  
Yu. K. Golikov ◽  
A. S. Berdnikov ◽  
A. S. Antonov ◽  
N. K. Krasnova ◽  
K. V. Solov’ev
Keyword(s):  
Electric Field ◽  
Field Homogeneity ◽  
Electric Field Homogeneity ◽  
Fringing Electric Field

Effect of Non-Uniform Tissue Configuration on Conductance Catheter Measurement for Arterial Lumen Sizing

2011 ◽  
Author(s):  
Hyo Won Choi ◽  
Ghassan S. Kassab
Keyword(s):  
Electric Field ◽  
Surrounding Tissue ◽  
Medium Size ◽  
Conductance Catheter ◽  
Cross Sectional ◽  
Tissue Properties ◽  
Arterial Lumen ◽  
Novel Approach ◽  
Parallel Conductance ◽  
The Impact

A novel approach of two bolus injections of saline solutions has been proposed for conductance catheter measurement of cross-sectional area (CSA) and parallel conductance for medium size arteries [1–2]. The parallel conductance or current leakage through surrounding tissue is dependent on how differently the combined configuration of lumen, surrounding tissue, and conductance catheter forms an electric field. Arteries have a variety of surrounding tissue geometries and electrical conductivities depending on their anatomic situations. Specifically, coronary/peripheral arteries are often characterized by their superficial anatomic positions so that surrounding tissue has asymmetric configurations. Such notions highlight the need for addressing the impact of anatomically relevant tissue properties on the performance of conductance catheter measurement. In the present study, we computationally probe how asymmetric surrounding tissue thickness and/or inhomogeneous/anisotropic electric conductivity of tissue can modulate the electric field and hence accuracy of CSA measurement for a medium size artery.

Left ventricular volume measurement in mice by conductance catheter: evaluation and optimization of calibration

2007 ◽  
Vol 293 (1) ◽  
pp. H534-H540 ◽  
Author(s):  
Jan Møller Nielsen ◽  
Steen B. Kristiansen ◽  
Steffen Ringgaard ◽  
Torsten Toftegaard Nielsen ◽  
Allan Flyvbjerg ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Hypertonic Saline ◽  
Left Ventricular ◽  
Volume Estimation ◽  
Left Ventricular Volumes ◽  
Conductance Catheter ◽  
Frequency Method ◽  
Parallel Conductance ◽  
Calibration Techniques

The conductance catheter (CC) allows thorough evaluation of cardiac function because it simultaneously provides measurements of pressure and volume. Calibration of the volume signal remains challenging. With different calibration techniques, in vivo left ventricular volumes (VCC) were measured in mice ( n = 52) with a Millar CC (SPR-839) and compared with MRI-derived volumes (VMRI). Significant correlations between VCC and VMRI [end-diastolic volume (EDV): R2 = 0.85, P < 0.01; end-systolic volume (ESV): R2 = 0.88, P < 0.01] were found when injection of hypertonic saline in the pulmonary artery was used to calibrate for parallel conductance and volume conversion was done by individual cylinder calibration. However, a significant underestimation was observed [EDV = −17.3 μl (−22.7 to −11.9 μl); ESV = −8.8 μl (−12.5 to −5.1 μl)]. Intravenous injection of the hypertonic saline bolus was inferior to injection into the pulmonary artery as a calibration method. Calibration with an independent measurement of stroke volume decreased the agreement with VMRI. Correction for an increase in blood conductivity during the in vivo experiments improved estimation of EDV. The dual-frequency method for estimation of parallel conductance failed to produce VCC that correlated with VMRI. We conclude that selection of the calibration procedure for the CC has significant implications for the accuracy and precision of volume estimation and pressure-volume loop-derived variables like myocardial contractility. Although VCC may be underestimated compared with MRI, optimized calibration techniques enable reliable volume estimation with the CC in mice.

Estimation of parallel conductance by dual-frequency conductance catheter in mice

2000 ◽  
Vol 279 (1) ◽  
pp. H443-H450 ◽  
Author(s):  
Dimitrios Georgakopoulos ◽  
David A. Kass
Keyword(s):  
Hypertonic Saline ◽  
Bolus Injection ◽  
Left Ventricular ◽  
Conductance Catheter ◽  
Dual Frequency ◽  
Frequency Method ◽  
Volume Determination ◽  
Saline Bolus ◽  
Parallel Conductance

The conductance catheter method has substantially enhanced the characterization of in vivo cardiovascular function in mice. Absolute volume determination requires assessment of parallel conductance ( V p) offset because of conductivity of structures external to the blood pool. Although such a determination is achievable by hypertonic saline bolus injection, this method poses potential risks to mice because of volume loading and/or contractility changes. We tested another method based on differences between blood and muscle conductances at various catheter excitation frequencies (20 vs. 2 kHz) in 33 open-chest mice. The ratio of mean frequency-dependent signal difference to V pderived by hypertonic saline injection was consistent [0.095 ± 0.01 (SD), n = 11], and both methods were strongly correlated ( r 2 = 0.97, P < 0.0001). This correlation persisted when the ratio was prospectively applied to a separate group of animals ( n = 12), with a combined regression relation of V p(DF) = 1.1 ∗ V p(Sal) − 2.5 [where V p(DF) is V p derived by the dual-frequency method and V p(Sal) is V p derived by hypertonic saline bolus injection], r 2 = 0.95, standard error of the estimate = 1.1 μl, and mean difference = 0.6 ± 1.4 μl. Varying V p(Sal) in a given animal resulted in parallel changes in V p(DF) (multiple regression r 2 = 0.92, P < 0.00001). The dominant source of V p in mice was found to be the left ventricular wall itself, since surrounding the heart in the chest with physiological saline or markedly varying right ventricular volumes had a minimal effect on the left ventricular volume signal. On the basis of V p and flow probe-derived cardiac output, end-diastolic volume and ejection fraction in normal mice were 28 ± 3 μl and 81 ± 6%, respectively, at a heart rate of 622 ± 28 min−1. Thus the dual-frequency method and independent flow signal can be used to provide absolute volumes in mice.

Sign in / Sign up

Export Citation Format

Share Document