1. Narine Sarvazyan, Ph.D. Pharmacology and Physiology Dept, The George Washington University Medical Center Arrhythmias Wave PROPAGATION disturbances Normal rhythm Reentry inlet 1inlet 2outlet stainless steel holder coverslip inlet 1 inlet 2 outlet A. CROSS SECTION B. BOTTOM VIEW I - Zone Peltier- controllered mount Plastic holder ** 25 mm pacing electrodes + = cells chamber I. Cellular Origins of Ectopic Arrhythmias Ectopic Wave INITIATION disturbances

2. In silico In vitro

3. BOUNDARY ACTIVITY in 3D: computer simulations Micro-reentries Ectopic beats

4. II. Stems cells & cardiac regeneration Contracting cells of cardiac lineage are fluorescent within attached embryoid body. Phase-contrast picture of attached embryoid body and its fluorescent image. embryoid body α-MHC-GFP construct III. Cardiotoxicity of anthracyclines Acknowledgement of financial support: NIH and American Heart Association Other areas of interest: doxorubicin induced oxidative stress Phospholipase A2 inhibition