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Hemodynamic changes with posture in calves with total artificial heart
K Fukamachi1, F Fukumura, R J Kiraly
1Department of Biomedical Engineering, Cleveland Clinic Foundation, OH 44195.
Insights
The Cleveland Clinic-Nimbus Total Artificial Heart (TAH) effectively adjusted pump flow and maintained aortic pressure (AoP) in response to postural changes in calves. This demonstrates TAH adaptability to hemodynamic shifts during both automatic and maximum pump rate periods.
Area of Science:
- Cardiovascular Engineering
- Biomedical Engineering
- Hemodynamics
Background:
- Postural changes significantly impact cardiovascular hemodynamics.
- Total Artificial Hearts (TAHs) aim to replicate native heart function, including response to physiological changes.
- Understanding TAH response to posture is crucial for patient management and device optimization.
Purpose of the Study:
- To analyze hemodynamic changes in Holstein calves equipped with the Cleveland Clinic-Nimbus Total Artificial Heart (TAH) during sitting versus standing postures.
- To evaluate the TAH's response to postural variations in both automatic (AUTO) and maximum (MAX) pump rate periods.
Main Methods:
- Five Holstein calves were instrumented with the Cleveland Clinic-Nimbus TAH.
- Hemodynamic parameters including right atrial pressure (RAP), left atrial pressure (LAP), pulmonary artery pressure (PAP), aortic pressure (AoP), and pump flow were continuously monitored.
- Data were collected over 120 days, averaged for sitting and standing positions during AUTO and MAX pump rate periods.
Main Results:
- During the AUTO period, standing resulted in significantly higher pump flow and lower systemic vascular resistance (SVR) compared to sitting.
- During the MAX period, standing was associated with significantly lower aortic pressure (AoP) and SVR than sitting.
- The TAH demonstrated adaptability by increasing pump flow and maintaining AoP during postural changes in the AUTO period.
Conclusions:
- The Cleveland Clinic-Nimbus TAH effectively responded to postural changes (sitting vs. standing) in calves.
- The device demonstrated adaptive pump flow regulation and maintained aortic pressure during the automatic control period.
- These findings support the TAH's potential for managing hemodynamic variability in patients.
Abstract:
Hemodynamic changes with posture, sitting versus standing, were analyzed in five Holstein calves with the Cleveland Clinic-Nimbus TAH. This total artificial heart (TAH) has a left master alternate control mode that adjusts the pump rate and consequently pump flow proportional to the pulmonary venous return to the left pump (AUTO period). However, in this series of experiments, the pump reached its maximum beat rate within 1-5 days post operatively, after which pump flow could not increase (MAX period). Hemodynamic parameters (RAP, LAP, PAP, AoP, and pump flow) were obtained every 15-20 min throughout the experiments for as long as 120 days and averaged for each posture for each period. During the AUTO period, the flow while standing was significantly higher than that while sitting (standing: 8.7 +/- 0.2 L/min; sitting: 7.5 +/- 0.4 L/min; p < 0.05), and the systemic vascular resistance (SVR) was significantly lower (standing: 895 +/- 93 dyne.sec.m-5; sitting: 1,041 +/- 124 dyne.sec.m-5; p < 0.05). During the MAX period, the AoP and SVR standing were significantly lower than those sitting (AoP standing: 91 +/- 7 mmHg; AoP sitting: 98 +/- 7 mmHg; p < 0.05; SVR standing: 652 +/- 75 mmHg; SVR sitting: 730 +/- 96 mmHg; p < 0.05). The Cleveland Clinic-Nimbus TAH responded well to these changes in position, increasing pump flow and maintaining the AoP during the AUTO period.