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Contrast Microsphere Destruction by a Continuous Flow Ventricular Assist Device: An In Vitro Evaluation Using a Mock
David G Platts1,2,3, Nicole Bartnikowski4, Shaun D Gregory2,3,5
1Department of Echocardiography, The Prince Charles Hospital, Brisbane, QLD, Australia.
Biomed Research International
|September 9, 2017
Summary
Contrast ultrasound agents experience significant signal reduction after passing through a continuous flow (CF) ventricular assist device (VAD). This destruction, evident at all pump speeds, was inversely related to pump speed, impacting VAD imaging.
Area of Science:
- Cardiovascular Engineering
- Medical Imaging Technology
- Biomedical Fluid Dynamics
Background:
- Transthoracic echocardiography (TTE) is crucial for managing patients with ventricular assist devices (VADs).
- Image quality in VAD patients can be challenging due to factors affecting ultrasound contrast agents.
- Contrast agents enhance echocardiographic visualization but are susceptible to hydrodynamic forces.
Purpose of the Study:
- To evaluate the impact of passing through a continuous flow (CF) VAD on ultrasound contrast agent concentration.
- To quantify the reduction in contrast signal intensity after transit through a CF-VAD.
- To assess the relationship between CF-VAD pump speed and contrast agent destruction.
Main Methods:
- A Heartware CF-VAD was integrated into a mock circulation loop (MCL).
- Definity® contrast agent was infused into the MCL.
- Ultrasound signal intensity (decibels) in defined regions of interest was measured before and after the CF-VAD as a surrogate for contrast concentration.
Main Results:
- A significant reduction in contrast signal intensity was observed post-CF-VAD compared to pre-CF-VAD across all tested pump speeds (p < 0.0001).
- An overall absolute reduction of 22.2% in contrast signal intensity occurred across the CF-VAD.
- The relative signal intensity reduction showed an inverse relationship with CF-VAD pump speed.
Conclusions:
- Transit through a CF-VAD causes significant destruction of contrast microspheres, leading to reduced signal intensity.
- This contrast destruction is consistently observed across all operational speeds of the CF-VAD.
- The degree of signal loss is inversely proportional to the pump speed, suggesting mechanical forces within the VAD are responsible.
