Nonlinear Conductance-Volume Relationship for Murine Conductance Catheter Measurement System

Wei, Chia-Ling; Valvano, Jonathan W.; Feldman, Marc D.; Pearce, John A.

doi:10.1109/tbme.2005.856029

Cited by 60 publications

(64 citation statements)

References 14 publications

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“…The conductance volume measurements underestimated ventricular volume as the volume was increased above 150ml. This finding is in accord with previous experimental studies [4,6].…”

Section: Discussionsupporting

confidence: 94%

“…Although conductance volume measurements can be calibrated against another synchronous estimate of ventricular volume [3,10,18], they are generally calibrated with an alternate measurement of stroke volume [6,10].…”

Section: Discussionmentioning

confidence: 99%

“…Conductance volume measurements are based on the assumption that the electric field produced by the conductance catheter is homogeneously distributed within the ventricular cavity [1]. However, theoretical and experimental studies have demonstrated that this assumption is not valid [4,5,6]. As a result, the conductance catheter tends to overestimate the volume in small ventricles and underestimate the volume in larger ventricles [2,3].…”

Section: Introductionmentioning

confidence: 99%

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Calibrating volume measurements made using the dual-field conductance catheter

McGuirk¹,

Barron²,

Ewert³

et al. 2009

JBiSE

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The conductance catheter technique allows realtime measurements of ventricular volume based on changes in the electrical conductance of blood within the ventricular cavity. Conductance volume measurements are corrected with a calibration coefficient, α, in order to improve accuracy. However, conductance volume measurements are also affected by parallel conductance, which may confound calibration coefficient estimation. This study was undertaken to examine the variation in α using a physical model of the left ventricle without parallel conductance. Calibration coefficients were calculated as the conductance-volume quotient (α V(t) ) or the stroke conductance-stroke volume quotient (α SV ). Both calibration coefficients varied as a non-linear function of the ventricular volume. Conductance volume measurements calibrated with α V(t) estimated ventricular volume to within 2.0 ± 6.9%. By contrast, calibration with α SV substantially over-estimated the ventricular volume in a volume-dependent manner, increasing from 26 ± 20% at 100ml to 106 ± 36% at 500ml. The accuracy of conductance volume measurements is affected by the choice of calibration coefficient. Using a fixed or constant calibration coefficient will result in volume measurement errors. The conductance-stroke volume quotient is associated with particularly significant and volume-dependent mea-surement errors. For this reason, conductance volume measurements should ideally be calibrated with an alternative measurement of ventricular volume.

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“…The conductance volume measurements underestimated ventricular volume as the volume was increased above 150ml. This finding is in accord with previous experimental studies [4,6].…”

Section: Discussionsupporting

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Calibrating volume measurements made using the dual-field conductance catheter

McGuirk¹,

Barron²,

Ewert³

et al. 2009

JBiSE

View full text Add to dashboard Cite

show abstract

“…Firstly, the current density generated by the conductance catheter is not uniformly distributed throughout the ventricular cavity [4,5,6]. This results in a non-linear conductance-absolute volume relationship [2,4,7].…”

Section: Introductionmentioning

confidence: 99%

Electrocardiographic interference and conductance volume measurements

McGuirk¹,

Ewert²,

Barron³

et al. 2009

JBiSE

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The conductance catheter technique enables continuous ventricular volume measurements based on the electrical conductance of blood within the ventricular cavity. However, ventricular excitation also produces a measurable electrical signal within the ventricular cavity. This study was undertaken to investigate the relationship between the ventricular electrogram and conductance volume measurements in a physical model of the left ventricle without parallel conductance. The ventricular electrogram was simulated with an ECG signal, ECG input connected to two ring electrodes within the model ventricle. Conductance volume measurements were made with and without ECG input . The difference between these measurements, G ECG (t), represented the conductance volume due to ECG input . G ECG (t) varied as a function of the first-derivative of ECG input with respect to time (r 2 =0.92, P<0.001). G ECG (t), This primarily affected volume measurements during ventricular depolarisation; during this phase the volume measurement error varied widely between -12% and +9%. As a result, end-diastole could not be reliably identified on the pressure-volume loop. The accuracy of conductance volume measurements during late diastole and early isovolumic contraction are substantially affected by the ventricular electrogram. This may result in a significant error in end-diastolic volume estimates, which has important implications for the quantitative assessment of ventricular function including, in particular, the assessment of chamber compliance.

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“…Baan's conductance-to-volume conversion equation was derived from inspection of the conductance-volume relationship of a cylinder placed in a homogeneous electric field [5,7]. However, the electrode-generated electric field is inhomogeneous (see Figure 1(c)), which makes the conductance-volume relationship nonlinear, and, thus, the accuracy of the linear Baan's equation is limited [7][8].…”

Section: Introductionmentioning

confidence: 99%

Mouse Left Ventricular Volume Estimation by Use of the Conductance Catheter Measurement System

Wei

Shih

2009

2009 IEEE Circuits and Systems International Conference on Testing and Diagnosis

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For cardiac gene researches, a method to quantify the cardiac functions is needed. Ventricular pressure-volume loop analysis is a standard tool to evaluate and quantify the myocardial and cardiac functions. The ventricular volume of transgenic mice is typically estimated by using the conductance catheter measurement system, which measures instantaneous ventricular conductance and then converts it into volume. The classic conductance-to-volume conversion equation was proposed by Baan et al. in 1984, but its accuracy is limited. The volume estimation accuracy of Baan's equation versus different possible mouse left ventricular volume ranges is investigated in this work.The results shows that the error of volume estimation is closely related to end-diastolic volume: the error increases with increasing end-diastolic volume. Therefore, it may not be appropriate to use Baan's equation on the mice with the disease of congestive heart failure, which results in larger end-diastolic volumes.

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Nonlinear Conductance-Volume Relationship for Murine Conductance Catheter Measurement System

Cited by 60 publications

References 14 publications

Calibrating volume measurements made using the dual-field conductance catheter

Calibrating volume measurements made using the dual-field conductance catheter

Electrocardiographic interference and conductance volume measurements

Mouse Left Ventricular Volume Estimation by Use of the Conductance Catheter Measurement System

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