Institute of Biomedical Engineering and Technology (IBiTech)

Cardiac hemodynamics

Background

Blood flow inside the heart is complex, driven by the cyclic contraction and relaxation of the heart on the one hand, and by the heart valves and ventricular geometry on the other hand. Most widely studied is the blood flow within the left ventricle, with an inflow from the left atrium, across the mitral valve into the left ventricle. Blood flow inside the heart was already studied by Leonardo Da Vinci and can now be visualized in-vivo with ultrasound or MRI in 3D. Understanding blood flow provides a deep insight into cardiovascular physiology, and blood flow patterns are used for the diagnosis of cardiac function, in particular for the assessment of the “diastolic function” of the heart, i.e., how well the ventricles gets filled prior to contraction. This is especially relevant for the diagnosis of heart failure: does the heart fail to fill adequately (e.g. due to insufficient relaxation or a too stiff ventricle due to fibrosis) or does it fail to contract.

In vitro and computer models of ventricular filling

The complexity of ventricular filling is beautifully illustrated in a video taken by dr. Hicham Saaid in a PIV-setup of a model of the left heart that he designed and built with Dr. Jason Voorneveld at TU Delft. As the heart relaxes, a jet enters the left ventricle, which initiates a vortex that sheds of the mitral valve to fill up the left ventricle. This vortex flow preserves momentum in the blood, which prevents that blood has to be accelerated from a zero velocity as the heart contracts and empties. Besides being energy-saving, the vortex flow also prevents stasis of blood inside the ventricle, and ensures a proper wash-out of blood and prevents thrombus formation.

Our research group has also been working on developing patient-specific computational models of intraventricular blood flow, starting from patient-specific data. In her PhD thesis, Dr. Alessandra Bavo used 3D ultrasound images of the ventricle and mitral valve, and used these data as input for a computational fluid dynamics model with imposed motion of the ventricle and mitral leaflets to simulate ventricular filling. The video below nicely visualizes how a vortex rolls of the leaflets of the mitral valve to fill the ventricle completely. The presence of the mitral valve leaflets is actually crucial for the formation of the jet and the vortex, and the wash-out of the ventricle as also studied in the PhD thesis of Federico Canè. The video below displays how particles, released in the apex of the left ventricle, are removed from the left ventricle in a model with and without a mitral valve. It is clear that in the model with the valve, the jet penetrates deep into the ventricle, stirring the particles that are more easily removed from the ventricle as the ventricle contracts. Such patient-specific computational models are helpful in assessing the impact of surgical interventions on the blood flow inside the heart, and will contribute to optimized medical device designs and therapies tailored to the individual patient.

IBiTech researchers currently active on the project

Patrick Segers (contact)

Funding sources

H2020 MUSICARE project (642458)

Finalized PhDs within IBiTech