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Am J Physiol Heart Circ Physiol 280: H475-H482, 2001;
0363-6135/01 $5.00
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Vol. 280, Issue 1, H475-H482, January 2001

SPECIAL COMMUNICATION
Validation and utility of novel volume reduction technique for determination of parallel conductance

Paul A. White1, Carl I. O. Brookes2, Hanne Ravn3, Vibeke Hjortdal3, Rajiv R. Chaturvedi1, and Andrew N. Redington1

1 Cardiothoracic Unit, Great Ormond Street Hospital For Children, London WC1N 3JH; 2 Department of Cardiology, Royal Brompton Hospital, London SW3 6NP, United Kingdom; and 3 Institute of Experimental Clinical Research, Skejby University Hospital, DK-8200 Aarhus N, Denmark


    ABSTRACT
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

The parallel conductance volume, created by the conductivity of structures surrounding the ventricular blood pool, can be estimated by using a saline dilution technique. This paper examines the use of a novel volume reduction method, during a standard vena caval preload reduction maneuver, as an alternative to the routinely used saline dilution method to calibrate conductance catheter measurements in the left (LV) and right ventricle (RV) of animals and humans. The serial reproducibility of both methods was examined by measurement of percent difference, and by assessing the coefficient of repeatability 1) between two measurements within the same subject, 2) between the two techniques, and 3) interobserver variability. The effect of ventricular size and contractile state on the volume reduction technique was also observed. It was essential to ensure the technique was not affected by inotropic state. The volume reduction technique and saline dilution method were repeated at three different loading states (baseline, 5, and 10 µg · kg-1 · min-1 of dobutamine). The coefficient of repeatability between serial measurements was similar for both the volume reduction and saline dilution methods, and good interobserver variability was demonstrated. The volume reduction technique was compared with the saline dilution technique over a large range of ventricular sizes. No significant difference was observed in the RV or LV of adult humans or in the LV of neonatal pigs and children. There was no significant effect on either the saline dilution or the volume reduction technique as the inotropic state increased. In conclusion, the volume reduction technique is neither affected by ventricular size nor contractile state, is repeatable between different observers, and can be used to substitute the saline dilution method when preload reduction of the ventricle is being employed.

saline dilution; right ventricle; left ventricle; ventricular volume; conductance catheter


    INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

TO DETERMINE ABSOLUTE VOLUME by using the conductance catheter technique, an estimate of the conductivity of structures surrounding the ventricular blood pool on parallel conductance is required. The contribution of this parallel conductance ranges from 50 to 70% of the total volume signal (5, 6, 13, 23, 24). It is therefore important to accurately quantify this volume offset. Parallel conductance volume is normally estimated by injection of hypertonic saline, which transiently changes the conductivity of the blood in the ventricle (2) and is the only method appropriate for general use. However, this technique has the disadvantage of inappropriate saline loading with multiple measurements, and is difficult to perform in small animals with high heart rates (12, 16, 22, 27). Furthermore, the characteristics of the injectate itself may alter the calculated values (14, 15) and hemodynamics (2, 12, 23). A different approach, using a suction method to determine parallel conductance (2, 27) has been described. The left ventricular cavity volume is transiently reduced to zero; the remaining volume signal therefore being parallel conductance. The method was first described in a study (2) of mongrel dogs; a good correlation (R = 0.86) being observed between the saline dilution and suction method. More recently, the technique was used in the small left ventricle of rats (27) where the parallel conductance volume by saline dilution was almost equal to the values obtained by the suction method.

The hemodynamic consequences of this technique are not well known, and this method is clearly impossible to use in patients. It may not be necessary to completely empty the ventricle, however. In this study we investigated a novel technique, which relies upon analysis of the transient reduction of volume induced by either manual snaring or balloon occlusion of the inferior (IVC) or superior vena cava (SVC). By extrapolating the linear relationship of a plot of the fall in end-diastolic volume (EDV) versus end-systolic volume (ESV) to a point where EDV equals ESV (which is the contracting heart must equal zero ventricular volume), an estimate of parallel volume (the remaining volume signal) was obtained. Clearly, anything that interferes with the linearity of the change in ESV or EDV or the relationship between the two may undermine this technique. The confounding factors that challenge the utility of this proposed method were examined.


    METHODS
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

The human study was approved by the Royal Brompton Hospital ethics committee, and informed written consent was obtained from all patients. The investigation conforms to the principles outlined in the Declaration of Helsinki (10). All of the animal studies conformed with the Guide for the Care and Use of Laboratory Animals published by the National Institutes of Health (21).

Conductance Catheter

The principles of the conductance technique to estimate ventricular volume have been described in detail (2, 3, 7) and have been extensively evaluated in the left ventricle. Briefly, the conductance catheter method to determine ventricular volume uses the measurement of the electrical conductance of blood in a ventricular cavity. The conductance catheter used in all of the measurements had eight equally spaced platinum ring electrodes.

An electric current of 20 kHz and 30 µA is applied between the two outermost electrodes (electrodes 1 and 8) to generate an intracavitary electric field. The remaining electrodes are used to measure the potential difference and therefore derive the time-varying conductance (Gt) of five ventricular segments. Total ventricular conductance is calculated as the sum of the segmental conductances. The relationship between time-varying volume (Vt) with Gt is given by the formula (2)
V<SUB><IT>t</IT></SUB><IT>=1/&agr;×L<SUP>2</SUP>&rgr;</IT>(<IT>G<SUB>t</SUB>−G</IT><SUB>p</SUB>)
where alpha  is the dimensionless slope factor, rho  is the blood resistivity, L is the interelectrode distance, and Gp is the parallel conductance. Left and right ventricular tissue, fluid, and the associated pericardial tissues also contribute to the total measured conductance. The offset volume, Vc, caused by the parallel conductance, Gp, is equal to
V<SUB>c</SUB><IT>=</IT>(<IT>1/&agr;</IT>)(<IT>L<SUP>2</SUP>×&rgr;</IT>)<IT>G</IT><SUB>p</SUB>

Volume Reduction Technique

Left and right ventricular volume was transiently reduced by caval obstruction (preload maneuver), during which a continuous measurement of ventricular conductance was made. The two most easily identified points from each successive cardiac cycle during the volume reduction are points of maximum (Vmax or end-diastolic volume) and minimum (Vmin or end-systolic volume), respectively. The EDV was plotted against the subsequent ESV of each of the first 10-12 beats during the transient reduction in volume. The relationship between EDV and ESV was assumed to be linear and was extrapolated to the line of identity by linear regression analysis. The fundamental basis of this technique is that in the contracting heart, the only value at which EDV and ESV are equal is when the ventricle is empty. Thus the volume at this point is the parallel conductance volume and is the result of current conducted through structures surrounding the ventricle. We analyzed a series of experiments to assess the utility of the technique.

Subjects

Data obtained from the following groups were analyzed retrospectively from previously stored studies. Group 1 used 17 adult (40 kg) Danish Landrace pigs (left and right ventricular estimations) and group 2 used 28 neonatal (5 kg) Danish Landrace pigs (left ventricular estimation). Group 3 included 33 adult humans (19 right ventricular and 14 left ventricular) undergoing coronary revascularization. In the right ventricular subgroup (18 males and 1 female) the age ranged from 43 to 70 yr (median = 62 yr) and weight ranged from 68.0 to 100.7 kg (median = 83.1 kg). In the left ventricular subgroup (14 males) the ages ranged from 50 to 67 yr (median = 58.5 yr) and weight ranged from 71.5 to 92.8 kg (median = 82.0 kg). Group 4 included 16 children (3 male and 13 female, left ventricular estimation) undergoing repair of congenital heart defects (none with interventricular communications). Their ages ranged from 0.25 to 16.0 yr (median 3.0 yr) and weight ranged from 4.8 to 60.8 kg (median 14.5 kg). Group 5 studied 10 adolescents and adults after the Mustard (20) procedure (5 male and 5 female) undergoing assessment of systemic ventricular performance (right ventricular estimation) during infusion of dobutamine (0, 5, and 10 µg · kg-1 · min-1). Their age ranged from 10 to 31 yr (median 15 yr) and weight ranged from 29.0 to 79.4 kg (median 62.6 kg). Briefly, the Mustard (20) procedure corrects the circulation in patients with transposition of the great arteries by redirecting pulmonary and systemic venous return with the use of an intra-atrial baffle. Thus the right ventricle remains as the systemic, subaortic ventricle.

General Methods

All of the studies were performed on anesthetized and sedated subjects and patients who were intubated and mechanically ventilated with positive pressure ventilation. Serial blood gas measurements were performed to maintain a physiological level of oxygenation and ventilation. The left ventricle was studied via the aorta (groups 1-3) or left ventricular apex (group 4) (9). The right ventricular studies were performed via the right ventricular outflow tract (groups 1-3) (6) or via the aorta (group 5). We used a conductance catheter with integrated micromanometer and an appropriate total interelectrode distance, which was selected on the basis of preoperative echocardiographic estimation of ventricular length. Correct placement of the conductance catheter in the ventricle was achieved by fluoroscopy (groups 1, 2, and 5) or by palpation (groups 3 and 4) and was confirmed by monitoring segmental volume-phase relationships and counterclockwise pressure-volume loops.

The conductance catheter was connected to a sigma-5 signal conditioning and processing unit (Cardiodynamics, Zoetermeer, The Netherlands). Analog signals representing the five segmental conductances, ventricular pressure, and electrocardiogram were digitized (12 bit, 250 Hz), monitored on-line, and stored on a personal computer for later analysis using custom-designed software (Biometrics, Las Vegas, NV). In group 1, left and right ventricular volumes were measured simultaneously; therefore, two signal conditioning and processing units were used, one being modified to use an excitation frequency of 19.5 kHz to prevent cross-talk from one ventricle to another. After we obtained an optimum conductance catheter position, a 4-ml blood sample was taken to measure rho .

A transient reduction in ventricular volume was imposed by manual snaring of the IVC or SVC in groups 1-4 and by balloon occlusion in group 5. Recordings were made during two maneuvers in each subject. To calculate parallel conductance by the saline dilution method, 10% hypertonic saline was injected (groups 1 and 3, 7 ml; group 2, 0.7 ml; group 4, 1-3 ml; and group 5, 5-6 ml) into the pulmonary artery to assess left ventricular parallel conductance and into the IVC to determine right ventricular parallel conductance. Again, two recordings were made. If ectopy occurred during the saline dilution or volume reduction, the recording was repeated to obtain at least two acceptable recordings. All of the measurements were performed during suspended ventilation at end expiration.

Protocol

Repeatability of techniques. To assess the potential use of a volume reduction technique to replace the saline dilution method, the serial reproducibility of each method was examined by measurement of percent difference and by assessing the coefficient of repeatability between two measurements within the same subject in groups 1 and 3. Having observed the serial repeatability, the mean difference and coefficient of repeatability was calculated to compare the saline and volume reduction techniques (groups 1-4).

Comparison of saline dilution method with volume reduction technique in different-sized ventricles. Comparative measurements were made in the right and left ventricles of adult pigs and humans (groups 1 and 3) and in the smaller left ventricle of children (group 4) and neonatal pigs (group 2).

Effect of ventricular contractility on volume reduction technique. The volume-reduction technique was performed in the systemic right ventricle of patients who had previously undergone repair of transposition of the great arteries (group 5). As part of another experimental protocol, patients were undergoing assessment of right ventricular performance at three different loading states (baseline, 5, and 10 µg of dobutamine). Two parallel conductance measurements were performed by both the saline dilution and volume reduction methods at each inotropic state.

Interobserver variability. Two blinded observers assessed the variability as a mean percent difference between measurements made in 21 randomly selected data sets. The average of two saline dilution (Vcsal) runs and two volume reduction (Vcsnare) runs analyzed by each observer was compared.

Data Analysis and Statistics

Data were expressed as a mean ± SD. Both a Bland-Altman method comparison and a linear regression, using the least-squares method, were used to determine the relationship between Vcsal and Vcsnare. The group mean Vcsal was compared with the Vcsnare using an ANOVA. The repeatability of the volume reduction technique was assessed using mean percent difference and coefficient of repeatability. The coefficient of repeatability, as described by Bland and Altman (4), is twice the standard deviation of the difference between two repeated measurements. A one-way ANOVA was used to compare Vcsal and Vcsnare for each loading state (baseline, 5, and 10 µg of dobutamine). A paired Student's t-test was used to compare the change in the end-systolic pressure volume relationship (ESPVR) from baseline to 10 µg of dobutamine in group 5. P < 0.05 was considered significant. The interobserver variability was expressed as a mean percent difference.


    RESULTS
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

Fewer than 15% of the runs performed were not of sufficient quality for analysis. The runs were excluded because of a poor r2 value (r2 < 0.80), artifacts making analysis difficult, multiple ectopic beats, or sustained arrhythmias during the transient snare of the vena cava. The data below are confined to those runs where adequate data were obtained.

Repeatability of Techniques for Groups 1 and 3

The repeatability of the volume reduction technique was calculated by comparing the mean percent difference between either two saline dilution Vcsal or Vcsnare measurements within the same subject. By plotting the difference of the serial saline dilution or volume reduction measurements against their mean, 95% of the differences were observed to be <2 SD in both pigs and humans. Furthermore, there was no relationship between the difference and the mean for the right and left ventricle in both groups. The coefficient of repeatability for two saline or volume reduction measurements was calculated (Table 1).

                              
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  		Table 1.   The measurements of parallel conductance using the saline dilution or volume reduction method in pigs and humans

The mean parallel conductance obtained by the volume reduction technique Vcsnare was compared with the mean parallel conductance derived from the standard saline dilution technique Vcsal by assessing both the mean percent differences between the two measurements and by calculating the coefficient of repeatability (Table 2).

                              
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  		Table 2.   Comparison of the volume reduction and saline dilution techniques by assessing the mean percent difference and coefficient of repeatability for all groups

Comparison of Saline Dilution Method with Volume Reduction Technique for Groups 1-4

In the left ventricle of one pig and the right ventricle of another in group 1, it was impossible to obtain Vcsnare because of noise and ectopics in the volume signal. These two pigs were removed from the subsequent analysis. A comparison of the saline dilution method to the volume reduction technique can be seen in Fig. 1. There was no significant difference in the parallel conductance results obtained by each method. Table 2 shows group data. Figures 2-4 show individual scatter plots for groups 1-4, with regression analysis. The group mean percent difference ranged from 8.5% for the adult human right ventricle to 23.9% for the neonatal pig left ventricle. By plotting the difference in parallel conductance between the saline dilution Vcsal and volume reduction Vcsnare techniques against the mean parallel conductance obtained by the two methods (Bland-Altman plot), 95% of the differences were observed to be <2 SD from the mean. The Bland-Altman method comparison is summarized nongraphically in Table 3.


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  		Fig. 1.   Comparison of the saline dilution method (Vcsal) with the volume reduction technique (Vcsnare) in the right ventricle (RV) of one pig. A: saline dilution method; hypertonic saline mixes with the blood in the ventricle producing a gradual transient increase in volume, whereas true volume and pressure remain constant. ECG, electrocardiogram. B: regression using paired minimal vs. maximal volumes generates a linear relation between observed volumes as a function of changing blood conductivity. Extrapolation to the line of identity (line A' corresponding to sigma  = 0) gives Vcsal (line B'). C: volume reduction technique; true ventricular volume will be decreased during the snare. D: regression using paired minimal vs. maximal volumes by a linear relation to the line of identity (A' corresponding to SV = 0) gives Vcsnare (B'). r2, correlation coefficient.



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  		Fig. 2.   A: relationship between Vcsal and Vcsnare in the human RV. B: comparison of Vcsal with Vcsnare in the adult left ventricle (LV). Dashed line, regression. Solid line, identity (Y = X).



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  		Fig. 3.   Linear regression analysis of parallel conductance derived by the saline dilution method to that obtained by the volume reduction technique in adult pig RV (A) and adult pig left ventricle (LV) (B). Dashed line, regression. Solid line, identity (Y = X).



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  		Fig. 4.   Linear regression analysis of parallel conductance derived by the saline dilution method to that obtained by the volume reduction technique in the human pediatric LV (A) and neonatal pig LV (B). Dashed line, regression. Solid line, identity (Y = X).


                              
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  		Table 3.   Bland-Altman method comparison used to compare Vcsal with Vcsnare

Effect of Ventricular Contractility on Volume Reduction Technique

The effect of changing contractile function, induced by incremental doses of dobutamine, on the volume reduction technique in eight patients in group 5 can be seen in Fig. 5, A and B. There was no significant effect on either the saline dilution method (baseline = 51.28 ± 25.05 ml; 10 µg dobutamine = 48.51 ± 21.45 ml, P = 0.816) or the volume-reduction technique (baseline = 52.64 ± 28.96 ml; 10 µg dobutamine = 59.32 ± 28.13 ml, P = 0.647) as the inotropic state increased, as observed from the increase in the ESPVR, which increased from 0.93 ± 0.51 to 3.16 ± 0.95 mmHg/ml, respectively, P < 0.001, as shown in the pressure-volume loops (Fig. 5B). There was good correlation between Vcsal and Vcsnare at all inotropic levels. Furthermore, by using a Bland-Altman method comparison, all points fell within the 95% limits of agreement for each inotropic state.


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  		Fig. 5.   A: linear regression analysis of Vcsal against Vcsnare to observe the effects of ventricular contractility on the volume reduction technique. CO, cardiac output. Dashed line, regression. Solid line, identity (Y = X). B: pressure volume loop for each inotropic state.

Interobserver Variability

The mean percent difference ranged from 6.06% for the saline dilution method Vcsal compared with 8.52% for the volume reduction method Vcsnare (P = not significant; ANOVA).


    DISCUSSION
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

Our data shows that a novel volume-reduction technique can substitute the routinely used saline dilution method to determine parallel conductance in the left and right ventricles of open- and close-chest animals and humans. There was no significant difference between Vcsal and Vcsnare for group data, although individual differences occurred in a few subjects. The technique also demonstrated good repeatability, including interobserver variability, and was neither affected by ventricular size nor contractile state.

Although obviating the need for the suction technique to completely empty the ventricle, the volume reduction technique that we have described relies on a similar theoretical basis. That is, in the beating heart, the only value at which EDV and ESV are equal is when the ventricular volume is zero. The difference between the suction technique and our technique is that we have estimated zero volume by extrapolating an assumed linear relationship between EDV and ESV during transient volume reduction. The linearity of this relationship is the key to the technique. This assumption was demonstrated by Sunagawa et al. (25) when describing the concept of effective arterial elastance (Ea). By using their formula, the following linear relation can be easily derived
ESV<IT>=</IT>[(<IT>E</IT><SUB>a</SUB><IT>/E</IT><SUB>max</SUB>)EDV<IT>+</IT>V<SUB>o</SUB>]<IT>/</IT>(<IT>1+E</IT><SUB>a</SUB><IT>/E</IT><SUB>max</SUB>)
where Emax is the slope of the ESPVR and Vo is its volume axis intercept.

On the assumption that Ea/Emax is constant during transient volume reduction, the above equation asserts the linear relationship between ESV and EDV. This theoretical relationship was confirmed in our study as, over the relatively small imposed volume change, the R2 values for the EDV-ESV relationship were consistently >0.90 and were highly reproducible. The assumed linear relationship between ESV and EDV was further demonstrated by Kass et al. (17) in a paper first describing IVC occlusion to measure contractility in humans. By using the volume reduction technique described in our paper on the data in Fig. 2B in Ref. 17, a parallel conductance volume Vcsnare of 21.5 ml was obtained compared with a parallel conductance volume Vcsal of 20.4 ml obtained with the normal hypertonic saline technique (Fig. 2D; Ref. 17).

Any factor that may affect this linearity would cause errors in the technique. There are many potential sources of error, none of which singly or in combination seems to lead to an important failure in the technique. One of the consequences of a presumed linear relationship between EDV and ESV during snaring the vena cava must be an assumed constancy of ejection fraction (EF), which clearly may not be the case when a ventricle is exposed to nonphysiological volume reduction. An additional practical advantage of examining the early phase of the snare is the relatively small change in ventricular volume that occurs well within the physiological range. Indeed, if major nonlinearity or nonconsistency of EF were imposed, then our results could not have been obtained. However, further validation would be required for analysis of data obtained over a wider generating range of ventricular volumes. Catheter movement could potentially affect parallel conductance determination. While the conductance catheter is kept in a relatively stable position during the saline dilution technique, it could potentially be displaced more during volume reduction. However, Boltwood et al. (5) demonstrated in the left ventricle by comparing conductance catheter measurements with those obtained from simultaneously performed biplane angiograms that no gross changes in catheter position occurred during IVC occlusion, although small changes in the relation of catheter to ventricular length were sometimes apparent. Throughout our experiments, the segmental volume signals were both consistent and in phase, suggesting that there were no deviations from an ideal catheter position during either the volume reduction or saline dilution techniques. Changes in parallel conductance and the gain constant, alpha , have been described during changes in ventricular volume. Changes in alpha  are unlikely to be important, because both EDV and ESV will be similarly affected. However, we (28, 29) and others (18, 26) have shown a nonsignificant change in both left ventricular and right ventricular parallel conductance volume during the cardiac cycle. Furthermore, larger changes in parallel conductance have been shown (1, 5) to occur in the left ventricle during larger imposed volume changes. The small changes in parallel conductance that occur during the cardiac cycle are unlikely to affect the technique, but the larger changes in parallel conductance that occur during major volume reduction might be expected to impose error. We were careful therefore only to analyze the first 10-12 cycles (i.e., the linear portion) during an imposed ventricular volume reduction. Despite an obvious change in the slope of the relationship of the ESPVR during unloading, it would seem that changes in inotropic state fail to significantly affect the relationship between EDV and ESV during the maneuver. Our study of the systemic right ventricle during dobutamine infusions (baseline, 5, and 10 µg · kg-1 · min-1) demonstrated a significant change in the ESPVR, but a remarkably consistent value for parallel conductance was measured with the volume reduction and the saline dilution techniques. This agrees with the finding of a uniform Vo (the intercept of the volume axis) during a reduction of ventricular volume no matter which isochrone of the pressure volume loop is taken. This is a fundamental requirement of the measurement of contractile state using the elastance technique and should be unaffected by changes in contractile state. Indeed, both Burkhoff and Maughan (Refs. 8 and 19; Figs. 5 and 7, respectively) have demonstrated that left ventricular Vo does not change with increasing contractile state, although Vo in the porcine right ventricle is prone to more change (11).

Perhaps the largest potential source of individual error, which in some cases was quite large when the saline dilution and volume reduction measurements were compared, is the serial error that may occur with both techniques. This could be caused by the inclusion of only a few beats during the linear portion of the volume reduction. The linear regression is therefore based on only a few closely spaced data points, which might lead to uncertainty in parallel conductance, because Vcsnare is obtained by a wide extrapolation. However, the serial error for both techniques is of a similar magnitude (~20%), an issue rarely mentioned in other studies using the saline dilution technique. Neither technique is perfect nor demonstrably superior in terms of accuracy. To some extent, the strength of agreement between the techniques, given the serial error, was surprisingly good. Furthermore, the ability to assess parallel conductance from the very maneuver most often performed in experimental studies of ventricular performance, without the superimposed problems of multiple boluses of hypertonic saline and therefore the need for repeat determinations of blood resistivity, makes the volume reduction technique an attractive alternative.

In summary, the volume reduction technique has good repeatability and is neither affected by ventricular size nor contractile state. This technique can therefore be used to substitute the saline dilution method.


    ACKNOWLEDGEMENTS

This work was supported by the Scott Rhodes Research Fund, Garfield Weston Research Fund and Clinical Research Committee (Royal Brompton and Harefield National Health Service Trust). This paper was presented in part at the European Medical And Biological Engineering Conference in Vienna, Austria, in November 1999.


    FOOTNOTES

Address for reprint requests and other correspondence: A. N. Redington, Cardiothoracic Unit, Great Ormond St. Hospital For Children, Great Ormond St., London WC1N 3JH, UK (E-mail: reding{at}attglobal.net).

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Received 14 June 2000; accepted in final form 7 August 2000.


    REFERENCES
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

1.   Applegate, RJ, Cheng CP, and Little WC. Simultaneous conductance catheter and dimension assessment of left ventricular volume in the intact animal. Circulation 81: 638-648, 1990[Abstract/Free Full Text].

2.   Baan, J, Van der Velde ET, Hein G, Debruin HG, Smeenk GJ, Koops J, Van Dijk AD, Temmerman D, Senden J, and Buis B. Continuous measurements of left ventricular volume in animals and humans by conductance catheter. Circulation 70: 812-823, 1984[Abstract/Free Full Text].

3.   Baan, J, Van der Velde ET, Steendijk P, and Koops J. Calibration and application of the conductance catheter for ventricular volume measurement. Automedica 11: 357-365, 1989.

4.   Bland, JM, and Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1: 307-310, 1986[ISI][Medline].

5.   Boltwood, CM, Appleyard RF, and Glantz SA. Left ventricular volume measurement by conductance catheter in intact dogs: parallel conductance volume depends on left ventricular size. Circulation 80: 1360-1377, 1989[Abstract/Free Full Text].

6.   Brookes, CIO, White PA, Bishop AJ, Oldershaw PJ, Redington AN, and Moat NE. Validation of a new intraoperative technique to evaluate load-independence indices of right ventricular performance in patients undergoing cardiac operations. J Thorac Cardiovasc Surg 116: 468-476, 1998[Abstract/Free Full Text].

7.   Burkhoff, D, Van der Velde ET, Kass D, Baan J, Maughan WL, and Sagawa K. Accuracy of volume measurement by conductance catheter in isolated ejecting canine hearts. Circulation 72: 440-447, 1985[Abstract/Free Full Text].

8.   Burkhoff, D, Sugiura S, Yue DT, and Sagawa K. Contractility-dependent curvilinearity of end-systolic pressure-volume relations. Am J Physiol Heart Circ Physiol 252: H1218-H1227, 1987[Abstract/Free Full Text].

9.   Chaturvedi, RR, Lincoln C, Gothard JWW, Scallan MH, White PA, Redington AN, and Shore DF. Left ventricular dysfunction after open repair of simple congenital heart defects in infants and children: quantification with the use of a conductance catheter immediately after bypass. J Thorac Cardiovasc Surg 115: 77-83, 1998[Abstract/Free Full Text].

10.   Declaration of Helsinki Acad Emerg Med 2: 177, 1964.

11.   Dickstein, ML, Yano O, Spotnitz HM, and Burkhoff D. Assessment of right ventricular contractile state with the conductance catheter technique in the pig. Cardiovasc Res 29: 820-826, 1995[ISI][Medline].

12.   Georgakopoulos, D, and Kass DA. Estimation of parallel conductance by dual-frequency conductance catheter in mice. Am J Physiol Heart Circ Physiol 279: H443-H450, 2000[Abstract/Free Full Text].

13.   Glantz, SA, Boltwood CM, Appleyard RF, Applegate RJ, Cheng CP, and Little WC. Volume conductance catheter. Circulation 81: 20-28, 1990[Abstract/Free Full Text].

14.   Herrera, MC, Olivera JM, and Valentinuzzi ME. Parallel conductance determination in cardiac volumetry using dilution manoeuvres: theoretical analysis and practical implications. Med Biol Eng Comput 37: 169-174, 1999[ISI][Medline].

15.   Herrera, MC, Olivera JM, and Valentinuzzi ME. Parallel conductance estimation by hypertonic dilution method with conductance catheter: effects of the bolus concentration and temperature. IEEE Trans Biomed Eng 46: 830-837, 1999[ISI][Medline].

16.   Ito, H, Takaki M, Yamaguchi H, Tachibana H, and Suga H. Left ventricular volumetric conductance catheter for rats. Am J Physiol Heart Circ Physiol 270: H1509-H1514, 1996[Abstract/Free Full Text].

17.   Kass, DA, Midei M, Graves W, Brinker JA, and Maughan WL. Use of a conductance (volume) catheter and transient inferior vena caval occlusion for rapid determination of pressure-volume relationships in man. Cathet Cardiovasc Diagn 15: 192-202, 1988[ISI][Medline].

18.   Lankford, EB, Kass DA, Maughan WL, and Shoukas AA. Does volume catheter parallel conductance vary during a cardiac cycle? Am J Physiol Heart Circ Physiol 258: H1933-H1942, 1990[Abstract/Free Full Text].

19.   Maughan, WL, Shoukas AA, Sagawa K, and Weisfeldt ML. Instantaneous pressure-volume relationship of the canine right ventricle. Circ Res 44: 309-315, 1979[Free Full Text].

20.   Mustard, WT. Successful two-stage correction of transposition of the great vessels. Surgery 55: 469-472, 1964[ISI][Medline].

21.  National Institutes of Health. Guide for the Care and Use of Laboratory Animals. NIH Publication No. 85-23, Revised 1985.

22.   Sato, T, Shishido T, Kawada T, Miyano H, Miyashita H, Inagaki M, Sugimachi M, and Sunagawa K. ESPVR of in situ rat left ventricle shows contractility-dependent curvilinearity. Am J Physiol Heart Circ Physiol 274: H1429-H1434, 1998[Abstract/Free Full Text].

23.   Steendijk, P, and Baan J. Comparison of intravenous and pulmonary artery injections of hypertonic saline for the assessment of conductance catheter parallel conductance. Cardiovasc Res 46: 82-89, 2000[Abstract/Free Full Text].

24.   Steendijk, P, Lardenoye JW, Van Der Velde ET, Sehalij MJ, and Baan J. Evaluation of a new transcardiac conductance method for continuous on-line measurement of left ventricular volume. Crit Care Med 28: 1599-1606, 2000[ISI][Medline].

25.   Sunagawa, K, Maughan WL, Burkhoff D, and Sagawa K. Left ventricular interaction with arterial load studied in isolated canine ventricle. Am J Physiol Heart Circ Physiol 245: H773-H780, 1983.

26.   Szwarc, RS, Mickleborough LL, Mizuno SI, Wilson GJ, Liu P, and Mohamed S. Conductance catheter measurements of left ventricular volume in the intact dog: Parallel conductance is independent of left ventricular size. Cardiovasc Res 28: 252-258, 1994[Abstract/Free Full Text].

27.   Tachibana, H, Takaki M, Lee S, Ito H, Yamaguchi H, and Suga H. New mechanoenergetic evaluation of left ventricular contractility in in-situ rat hearts. Am J Physiol Heart Circ Physiol 272: H2671-H2678, 1997[Abstract/Free Full Text].

28.   White, PA, Chaturvedi RR, Bishop AJ, Brookes CIO, Oldershaw PJ, and Redington AN. Does parallel conductance vary during systole in the human right ventricle? Cardiovasc Res 32: 901-908, 1996[ISI][Medline].

29.   White, PA, Chaturvedi RR, Shore D, Lincoln C, Bishop AJ, Oldershaw PJ, and Redington AN. Does left ventricular parallel conductance change during the cardiac cycle? Observations in infants and children with congenital heart disease. Am J Physiol Heart Circ Physiol 273: H295-H302, 1997[Abstract/Free Full Text].

Am J Physiol Heart Circ Physiol 280(1):H475-H482
0363-6135/01 $5.00 Copyright © 2001 the American Physiological Society


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