Distal thoracic aorta hemodynamics during exercise with continuous flow left ventricular assist system

Area of Science:

• Cardiovascular Engineering
• Biomedical Engineering
• Hemodynamics

Background:

• Continuous flow left ventricular assist systems (LVAS) are increasingly considered for destination therapy.
• Patients with LVAS are expected to engage in increased daily activities, including exercise.
• Understanding the impact of exercise on blood flow dynamics in LVAS patients is crucial.

Purpose of the Study:

• To analyze the effects of exercise on distal thoracic aorta blood flow in animals with continuous flow LVAS.
• To compare blood flow patterns at different pump flow rates (PFR) during and after exercise.

Main Methods:

• Five calves implanted with continuous flow LVAS underwent treadmill exercise.
• Exercise was performed at two pump flow rates: high (60-80% of pulmonary artery flow) and low (25-30%).
• Flow waves in the pump, pulmonary artery, and descending thoracic aorta were recorded, and systolic/diastolic volumes were calculated.

Main Results:

• Pulmonary artery and descending thoracic aorta flow rates increased with heart rate during exercise, with no significant group differences.
• Pump regurgitation increased during exercise, with sustained regurgitation observed post-exercise only at low PFR.
• Descending thoracic aorta systolic volume increased during high PFR exercise, while diastolic volume decreased at both PFRs post-exercise, particularly at low PFR.

Conclusions:

• Exercise can temporarily increase pump regurgitation in continuous flow LVAS.
• Descending thoracic aorta blood flow is largely maintained by increased heart rate during exercise.
• A decrease in diastolic flow post-exercise at lower pump flow rates warrants further investigation for potential hemodynamic implications.