Numeric modeling of the cardiovascular system with a left ventricular assist device

Area of Science:

• Biomedical Engineering
• Computational Physiology
• Medical Device Modeling

Background:

• The cardiovascular system (CVS) requires advanced support in cases of heart failure.
• The Cleveland Clinic Implantable Ventricular Assist System (IVAS) is a nonpulsatile rotary pump designed to assist the failing left ventricle.
• Understanding the hemodynamic interactions between the CVS and assist devices is crucial for optimizing performance.

Purpose of the Study:

• To observe hemodynamic interactions between the cardiovascular system (CVS) and the Implantable Ventricular Assist System (IVAS) under diverse physiological and pathophysiological conditions.
• To enable testing and optimization of various IVAS control algorithms.
• To evaluate the efficacy of IVAS in augmenting failing left ventricles.

Main Methods:

• Development of a numerical model integrating a lump-parameter CVS model with an IVAS pump model.
• Modification of an existing CVS model (24 coupled differential equations) to incorporate the IVAS pump characteristics derived from in vitro testing.
• Conducting computer simulations for ventricles with normal and abnormal function across various exercise levels and pump speeds.

Main Results:

• Numerical modeling proved effective in predicting the hemodynamic response of the CVS to IVAS under various conditions.
• The IVAS demonstrated normalization of cardiac output, particularly in failing hearts, albeit with a reduction in pulse pressure.
• Simulations indicated the feasibility of developing adaptive IVAS control algorithms.

Conclusions:

• Computational modeling is a valuable tool for assessing the hemodynamic impact of ventricular assist devices.
• IVAS shows promise in restoring cardiac output in heart failure patients.
• The study supports the development of sophisticated control strategies for IVAS to match physiological demands.