Submitted on October 6, 2007
Accepted on February 29, 2008
Location of ectopic beats coincide with spatial gradients of NADH in a regional model of low-flow reperfusion
Matthew W Kay1, Luther M Swift2, Brian Martell3, Ara Arutunyan4, and Narine Sarvazyan5*
1 Electrical and Computer Engineering, The George Washington University, Washington , District of Columbia, United States
2 Pharmacology and Physiology, The George Washington University, Washington, District of Columbia, United States
3 Pharmacology and Physiology, The George Washington University, District of Columbia, United States
4 Washingtod, District of Columbia, United States; Pharmacology and Physiology, The George Washington University, Washington , United States
5 Pharmacology and Physiology, The George Washington University, Washington , United States
* To whom correspondence should be addressed. E-mail: phynas{at}gwumc.edu.
We studied the origins of ectopic beats during low-flow reperfusion after acute regional ischemia in excised rat hearts. The left anterior descending coronary artery was cannulated. Perfusate was delivered to the cannula using an HPLC pump. This provided not only precise control of flow rate, but also avoided mechanical artifacts associated with vessel occlusion and de-occlusion. Optical mapping of epicardial transmembrane potential served to identify activation wavefronts. Imaging of NADH fluorescence was used to quantify local ischemia. Our experiments suggest that low-flow reperfusion of ischemic myocardium leads to a highly heterogeneous ischemic substrate and that the degree of ischemia between adjacent patches of tissue changes in time. In contrast to transient ectopic activity observed during full-flow reperfusion, persistent ectopic arrhythmias were observed during low-flow reperfusion. The origins of ectopic beats were traceable to areas of high spatial gradients of changes in NADH fluorescence caused by low-flow reperfusion.
