Abstract
Background
In vivo testing presents challenges for testing circulatory assist devices including cost, ethical concerns and long testing durations. Mock circulatory loops (MCL) are an alternative method to simulate key characteristics of the circulatory system. Team Bath Heart are using a custom low budget MCL for testing total artificial heart (TAH) prototypes; here the new pulmonary loop is compared with the original systemic loop.
Methods
Following the Windkesel model, the systemic system uses two closed-air chambers for arterial and atrial compliance, and an open-air chamber for venous compliance due to high compliance requirements. The pulmonary system uses three closed air chambers due to the lower venous compliance requirement.
Water was chosen as a blood analogue as the system requires repeat draining, making a water-glycol mix economically unviable. Standard components were used to keep cost low. Parts such as the chamber bases were 3D printed with an SLA printer as shown in Figure 1.
Results
Both pulmonary and systemic loops were tested at 5LPM. Pressure, compliance and resistance values were recorded. The systemic system has physiologically accurate pressure, shown in Figure 2, with MAP around 80 mmHg, however, has minimal dicrotic notch and small pulse pressure around 20 mmHg. The pulmonary system has significant hypertension, with MAP around 60 mmHg, likely due to high liquid volumes although pulse pressures were realistic reducing from around 20 mmHg. The resistance and compliance values achieved were within a few percent of the target ranges. The total cost of the pulmonary system is £552.63 with the original systemic system costing £860.
Conclusion
The systemic loop replicates patient conditions with physiologically accurate arterial waveforms. The pulmonary circulation produces unphysiologically high pressures. In future the pulmonary loop will be redesigned to reduce the fluid volume and both loops will be used for testing the TAH.
In vivo testing presents challenges for testing circulatory assist devices including cost, ethical concerns and long testing durations. Mock circulatory loops (MCL) are an alternative method to simulate key characteristics of the circulatory system. Team Bath Heart are using a custom low budget MCL for testing total artificial heart (TAH) prototypes; here the new pulmonary loop is compared with the original systemic loop.
Methods
Following the Windkesel model, the systemic system uses two closed-air chambers for arterial and atrial compliance, and an open-air chamber for venous compliance due to high compliance requirements. The pulmonary system uses three closed air chambers due to the lower venous compliance requirement.
Water was chosen as a blood analogue as the system requires repeat draining, making a water-glycol mix economically unviable. Standard components were used to keep cost low. Parts such as the chamber bases were 3D printed with an SLA printer as shown in Figure 1.
Results
Both pulmonary and systemic loops were tested at 5LPM. Pressure, compliance and resistance values were recorded. The systemic system has physiologically accurate pressure, shown in Figure 2, with MAP around 80 mmHg, however, has minimal dicrotic notch and small pulse pressure around 20 mmHg. The pulmonary system has significant hypertension, with MAP around 60 mmHg, likely due to high liquid volumes although pulse pressures were realistic reducing from around 20 mmHg. The resistance and compliance values achieved were within a few percent of the target ranges. The total cost of the pulmonary system is £552.63 with the original systemic system costing £860.
Conclusion
The systemic loop replicates patient conditions with physiologically accurate arterial waveforms. The pulmonary circulation produces unphysiologically high pressures. In future the pulmonary loop will be redesigned to reduce the fluid volume and both loops will be used for testing the TAH.
| Original language | English |
|---|---|
| Publication status | Published - 13 Nov 2024 |
| Event | 30th Congress of the International Society for Mechanical Circulatory Support (ISMCS) - Light Cube, Utsunomiya, Japan Duration: 13 Nov 2024 → 15 Nov 2024 https://kinki-convention.jp/ismcs30/ |
Conference
| Conference | 30th Congress of the International Society for Mechanical Circulatory Support (ISMCS) |
|---|---|
| Country/Territory | Japan |
| City | Utsunomiya |
| Period | 13/11/24 → 15/11/24 |
| Internet address |