UC San Diego

Many studies have shown that strain measurements are becoming viable for diagnostic and clinical purposes. Strain has shown potential in serving as early indicator for a host of cardiac diseases such coronary disease, hypertension, etc. Therefore, it is crucial to develop techniques to accurately determine strain. There are many different methods to measure cardiac regional mechanics using a variety of techniques such as Doppler echocardiographic imaging as well harmonic phase algorithm (HARP). These methods are popular, as they have produced accurate systolic strains. However, both methods have their limitations. Previous studies have combined HARP with finite element modeling to compute 3D circumferential, radial and longitudinal strains in mice, however they limited their calculations to the left ventricle. Here, we use combine MRI, DT-MRI, and HARP to measure the same distributions, but in addition, we measure fiber, sheet- normal and cross-fiber strains in both the left and right ventricle. In order to examine this structure-function relationship, we will determine regional function in the left and right ventricle using a structure-dependent computational model of cardiac mechanics. Using normotensive and hypertensive rat hearts models, we will quantify the time course of regional strain throughout the left and right ventricle. These measures, along with ECG and blood pressures, will be used as inputs to a finite element model of the contracting ventricles. The goal of these studies will be to determine if these measures are sufficient to produce accurate strain fields in rat hearts