In-vivo measurement of strain field gradients in an amphibian heart after artificially-induced myocardial infarction

Heart Attacks result when blood flow to a section of the heart muscle is restricted and the heart muscle begins to die due to lack of oxygen. This study uses a liquid nitrogen technique to simulate heart attacks in vivo using amphibian hearts. Liquid nitrogen is applied to sections of the heart using a metal probe. Using this technique the size and location of the damaged heart muscle can be carefully controlled. The effect of damage on the heart is monitored using a non-contact optical full field strain technique referred to as speckle image photogrammetry. This technique uses high speed cameras (up to 500 frames per second) to monitor the full strain field over the entire three dimensional surface of the heart as it beats. Using this technique the effect of the induced muscle damage on the surrounding myocardium is monitored throughout the entire heart beat cycle. Pressure changes throughout the ventricle are also monitored using a pressure transducing catheter, which is synchronized with the photogrammetry system. This study is specifically concerned with how the redistribution of strain around the damaged heart muscle results in additional damage to the heart. Preliminary results show that artificially induced myocardial infarction results in a reduction in Z displacement of -0.16 mm, an increase in Major Strain of 1.24%, and an increase in Minor Strain of 2.99%. Future research will attempt to extrapolate yielded results to the human heart and relate the observed changes to heart degradation over time