Unipolar QS Morphology and Purkinje Potential of the Free Left Ventricular Wall

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Abstract
The entire thickness of the free left ventricular wall was systematically explored in 16 dogs by means of bipolar and unipolar intramural leads. The distribution of unipolar QS morphologies was found to depend upon the anatomic region explored and this, in turn, to vary from animal to animal. Unipolar QS complexes were recorded in less than 50% of all the points explored. Purkinje potentials were usually recorded at the endocardial surface and at 1 and 2 mm from it. The distribution of Purkinje potentials is considered the main factor for the registration of unipolar QS morphologies at variable depths into the myocardium of the left ventricular wall is conceived to start at the junction between Purkinje and muscle fibers by a number of closed polarized spheres, which independently cause a sequence of simultaneously activated points toward the endocardium and toward the epicardium. In the course of ventricular activation, closed polarized spheres may collide among themselves and may interfere with spheres of activation open to the endocardium. The speed of conduction in ventricular regions with unipolar QS morphologies cannot be calculated, since different activation fronts may reach the points that are being explored. The concept of electrical endocardium for the free left ventricular wave is presented.