Abstract
Mechanical stress is known to alter the electrophysiological property of myocardium and may trigger fatal arrhythmias when an abnormal load is applied to the heart. We developed novel techniques combining experiment and simulation to elucidate the mechanisms of stretch-induced arrhythmias. We applied transient global stretch to arterially perfused rabbit right ventricular wall preparations. The distribution of strain (determined by marker tracking) and membrane potential (measured by optical mapping with the voltage-sensitive dye, di-4-ANEPPS) were simultaneously recorded while accounting for the motion artifact and the 3-D morphology of preparations was examined by the laser scanner. To further investigate the mechanisms of stretch-induced arrhythmogeneicity, we performed a computer simulation based on finite element method (FEM) . Although the uniform stretch was applied globally, the medium stretch (10∼15%) initiated the excitation from a local spot. On the other hand, the large stretch (> = 20%) caused the synchronous excitation of entire preparation. Computer simulation based on the heterogeneous morphology creates the inhomogeneous strain distribution in response to the stretch, and the focal excitation was observed where the tissue thickness was thin. Our computer simulation also indicates that this focal excitation induced by the medium stretch develop to the stretch-induced spiral wave formation. The inhomogeneous structure of the ventricular wall modulated the globally applied stretch to create heterogeneous strain distribution. Global stretch of medium intensity, rather than intense one, may trigger the fatal arrhythmia.
