Description
Pulmonary artery hypertension (PAH) is a form of cardiovascular disease (CVD) which affects millions of Americans. PAH manifests itself in the form of an increased mean pulmonary artery pressure (MPAP) creating resistance against blood flowing from the right heart to the lungs. What begins with negligible symptoms can quickly develop into a complete inability to perform trivial physical activities like standing or walking if the disease is not treated in its earliest stages. If left untreated, MPAP continues to rise, causing an increase in muscle mass and bowing of the RV as it uncouples from the left heart. These consequences of late-stage PAH directly lead to heart failure (HF). The goal of these studies was to create a novel, quantitative approach to analyzing a patient’s hemodynamics and blood flow patterns through the right ventricle (RV). Current diagnostic methods are intrusive or limited to qualitative analyses, both of which have many downsides. The current standard of treatment for PAH is a lung transplant which is an expensive, intensive, and limited option due to the lack of availability. Experimental studies were performed using a silicone, patient-specific, RV model in a cardiac simulator. Using a series of pressure sensors and flow monitors, the hemodynamics within the RV and the pulmonary artery were recorded. To analyze blood flow patterns through the asymmetric RV, a stereoscopic (3D) system of particle image velocimetry (PIV) was machined, developed, and utilized. Variable resistors in the mock circulatory loop allowed for simulation of normal and diseased states at MPAP values ranging from 14mmHg to approximately 60mmHg. Hemodynamic measurement showed that as the MPAP increased, the stroke work, or the relative “effort” required to eject a sufficient amount of blood, increased. These findings presented the effects that even slight increases in MPAP can have on the right heart. Using the novel stereo-PIV system, the out-of-plane (Vz) flow over the pulmonary valve was identified as a possible index for detection of early-stage PAH. At the RV outflow, high Vz in PAH conditions correspon ed to a higher percentage of blood remaining with the ventricle throughout the cardiac cycle.
