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Assessment of circulating blood volume in calves with a total artificial heart
K Fukamachi1, M E Benavides, K E Wika
1Department of Biomedical Engineering, Cleveland Clinic Foundation, Ohio 44195, USA.
Insights
Measuring circulating blood volume (CBV) with indocyanine green dye is simple and cost-effective for total artificial heart (TAH) research. TAH implantation significantly increased CBV, unlike mitral valve replacement, suggesting hemodilution may cause anemia in TAH patients.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Hemodynamics
Background:
- Accurate measurement of circulating blood volume (CBV) is crucial for assessing hemodynamic performance in total artificial heart (TAH) recipients.
- Previous methods for CBV measurement, often involving radionuclides, had limitations in terms of cost, complexity, and frequency of use.
Purpose of the Study:
- To evaluate the utility of indocyanine green dye for measuring CBV in calves with a TAH.
- To compare CBV changes in calves with a TAH versus those undergoing mitral valve replacement.
- To investigate the relationship between CBV, right atrial pressure, and hematocrit in TAH recipients.
Main Methods:
- Indocyanine green dye dilution method was used for CBV measurements in calves.
- Reproducibility was assessed in normal calves, and precision was confirmed by pre-operative measurements in both TAH and control groups.
- CBV was monitored post-operatively in calves with a Cleveland Clinic-Nimbus TAH and compared to a control group with mitral valve replacement.
Main Results:
- The indocyanine green dye method demonstrated good reproducibility (RSD 3.9 +/- 2.4%) and precision.
- Calves with TAH showed a more than twofold increase in CBV after 2 weeks, while the mitral valve replacement group showed no significant change.
- No correlation was found between right atrial pressure and CBV (r = 0.08), but a negative correlation existed between hematocrit and CBV, suggesting hemodilution.
Conclusions:
- Indocyanine green dye offers a simple, cost-effective, and repeatable method for CBV measurement in TAH research.
- TAH implantation leads to a significant increase in CBV, independent of right atrial pressure changes.
- Hemodilution, indicated by the negative correlation between hematocrit and CBV, may contribute to anemia observed in TAH animals.
Abstract:
Measurement of the circulating blood volume (CBV) is essential to a proper understanding of the hemodynamic performance of total artificial hearts (TAHs). Recently, the authors employed CBV measurements using indocyanine green dye in calves with a TAH. The advantages of this method over previous methods using radionuclides include simplicity, low cost, and the capability of repeated and frequent measurements. Reproducibility of the measurements was demonstrated in three normal calves with a relative standard deviation of 3.9 +/- 2.4%. CBV was measured in eight calves with the Cleveland Clinic-Nimbus TAH and compared with that of seven calves that underwent mitral valve replacement. Small standard deviations in pre operative values in both TAH and mitral valve replacement groups demonstrated the precision of CBV measurements. Although there was no change in CBV in the mitral valve replacement group, CBV in the TAH group increased to more than twice the pre operative value after 2 weeks. Although the right atrial pressure increased similarly after TAH implantation, there was no correlation (r = 0.08) between the right atrial pressure and CBV, which suggested a possible inaccuracy in estimating CBV from the right atrial pressure. A negative correlation between the hematocrit value and CBV suggested that hemodilution might be one of the causes of anemia observed in our TAH animals.