Abstracts Health Sciences

The anti-arrhythmic effects of constant diastolic interval pacing in a numerical model of a canine cardiac ventricular fiber

by Christopher Johnson

Beat to beat changes in action potential duration (APD) are known as alternans. Alternans are precursors for cardiac arrhythmias that may lead to heart failure and sudden cardiac death. Sudden cardiac death makes up 15-20% of all deaths annually in the United States (Deo, [28]). Alternans are known to form in association with periodic pacing protocol, during which the basic cycle length (BCL) is held constant. Periodic pacing incorporates feedback from the previous action potential, allowing for the formation of alternans. Constant diastolic interval (DI) pacing relies on the elimination of feedback within the system, and through the elimination causes the suppression of alternans. It has previously been shown that alternans suppression within a single cell model is possible (McIntyre, [22]). This research focuses on the presence and behavior of alternans in a 150 cell (1.5cm) and a 300 cell (3cm) cable during constant BCL and constant DI pacing. Alternans did appear for constant DI pacing for DI values lower than 20ms, representing a non-physiological range. However, we found that alternans could be controlled using a constant DI pacing protocol for both a short and long cable when using physiological ranges for DI, above 30ms.