VERTEX SHEDDING AS A PRECURSOR OF TURBULENT ELECTRICAL-ACTIVITY IN CARDIAC-MUSCLE

In cardiac tissue, during partial blockade of the membrane sodium chan nels, or at high frequencies of excitation, inexcitable obstacles with sharp edges may destabilize the propagation of electrical excitation waves, causing the formation of self-sustained vortices and turbulent cardiac electrical activity, The formation of such vortices, which vis ually resembles vortex shedding in hydrodynamic turbulent flows, was o bserved in sheep epicardial tissue using voltage-sensitive dyes in com bination with video-imaging techniques. Vortex shedding is a potential mechanism leading to the spontaneous initiation of uncontrolled high- frequency excitation of the heart.