[Effects of Evan Blue on perfused dimension display and rabbit left ventricular action potential]

Simultaneous recording of transmembrane action potential at endocardium, midcardium and epicardium and transmural ECG in arterially perfused left ventricular preparation is a new method for researching into the mechanism about ventricular arrhythmia, and in this connection, how to distinguish the perfused area plays a key role in keeping preparations under normal condition. This study is aimed to evaluate the effects of Evan Blue on the displaying of the perfused area and on the characters of transmembrane action potential of the arterially perfused left ventricular preparations.

Rabbit left ventricular wedge preparations were perfused with Tyrode solution continuously via left circumflex, and the action potential of endocardium, midmyocardium, epicardium or transmural electrocardiogram were recorded simultaneously. The action poatential duration (APD), transmural dispersion of repolarization (TDR) or QT intervals were compared and the color variation of the preparations were studied before and 30 min after perfusion with Evan Blue.

Under the basic stimulatory cycle length of 1000, 2000, 4000 ms, there was no significant difference of APD in the same transmural layer or TDR before and after Evan Blue perfusion (P<0.01), but APD or TDR stimulated at basic cycle length of 1000-4000 ms were all higher than those recorded at 500 ms (P<0.01); APDs of endocardium were much longer than those of epicardium or midmyocardium (P<0.01); there was no significant difference in APD, TDR and QT intervals before and after Evan Blue perfusion (P>0.05). No premature ventricular contractions and ventricular tachycardia happened during the experiments.

Evan Blue can be used as a marker to identify the perfused area.