A computer model of normal conduction in the human atria

Although considerabIe progress has been made in understanding the process o f wavefront propagation and arrhythmogenesis in human atria, technical conc erns and issues of patient safety have limited experimental investigations. The present work describes a finite volume-based computer model of human a trial activation and current flow to complement these studies. Unlike previ ous representations, the model is three-dimensional, incorporating bath the left and right atria and the major muscle bundles of the atria, including the crista terminalis, pectinate muscles, limbus of the fossa ovalis, and B achmann's bundle. The bundles are represented as anisotropic structures wit h fiber directions aligned with the bundle axes. Conductivities are assigne d to the model to give realistic local conduction velocities within the bun dles and bulk tissue. Results from simulations demonstrate the role of the bundles in a normal sinus rhythm and also reveal the patterns of activation in the septum, where experimental mapping has been extremely challenging. To validate the model, the simulated normal activation sequence and conduct ion velocities at various locations are compared with experimental observat ions and data. The model is also used to investigate paced activation, and a mechanism of the relative lengthening of left versus right stimulation is presented. Owing to both the realistic geometry and the bundle structures, the model can be used for further analysis of the normal activation sequen ce and to examine abnormal conduction, including flutter. The full text of this article is available at http://www.circresaha.org.