Effects of heart isolation, voltage-sensitive dye, and electromechanical uncoupling agents on ventricular fibrillation

Abstract

We tested whether the interventions typically required for optical mapping affect activation patterns during ventricular fibrillation (VF). A 21 x 24 unipolar electrode array (1.5 mm spacing) was sutured to the left ventricular epicardium of 16 anesthetized pigs, and four episodes of electrically induced VF (30-s duration) were recorded. The hearts were then rapidly excised and connected to a Langendorff perfusion apparatus. Four of the hearts were controls, in which 24 additional VF episodes were then mapped. In the remaining 12 hearts, four VF episodes were mapped after isolation, four more episodes were mapped after exposure to the voltage-sensitive dye di-4-ANEPPS, and six more episodes were mapped after exposure to the electromechanical uncoupling agents diacetyl monoxime (DAM; 20 mmol/l, n = 6) or cytochalasin D (CytoD; 10 micromol/l, n = 6). VF episodes were separated by 4 min. VF activation patterns were quantified using custom pattern analysis algorithms. From comparisons with time-corrected control data, all interventions significantly changed VF patterns. Most changes were broadly consistent with slowing and regularization due to loss of excitability. Heart isolation had the largest effect on VF patterns, followed by CytoD, DAM, and dye.

Interstitial volume modulates the conduction velocity-gap junction relationship

“…In our Langendorff-perfused ventricle preparations (without ischemia), it reduced V IS relative to control (Fig. 3), consistent with previous studies (2,31).…”

“…In all experiments, control Tyrode's solution was perfused for 35 min followed by Tyrode's solution containing either albumin (4 g/l) or mannitol (26.1 g/l/143.2 mOsm), compounds demonstrated to reduce myocardial tissue water content (2,31,35), for 15 min. The osmolarity of the Tyrode's solution with albumin was not significantly different relative to control (290.7 Ϯ 1.8 and 291.0 Ϯ 4.2 mOsm, respectively), whereas the osmolarity of the mannitol solution was significantly higher than both (406.7 Ϯ 1.9 mOsm; P Ͻ 0.05).…”

A technical review of optical mapping of intracellular calcium within myocardial tissue

“…Elimination of the motion artifact requires suppression of contraction using electromechanical uncoupling agents (7,28,77) or, less frequently, mechanical constraint (112). Blebbistatin is a popular uncoupling agent for optical mapping, especially when imaging Ca i 2ϩ because it specifically inhibits the myosin ATPase without altering sarcolemmal ion currents or SR Ca 2ϩ kinetics (28).…”

Activation Patterns of Purkinje Fibers During Long-Duration Ventricular Fibrillation in an Isolated Canine Heart Model

“…The pH was maintained in the range of 7.35 to 7.45. 16 The ground reference for the mapping system was attached to the aortic root.…”