The relation between atrial fibrillation wavefront characteristics and accessory pathway conduction.

Abstract

Although the source-sink relationship for impulse propagation in cardiac tissues has been demonstrated in vitro, there has been no verification of this hypothesis in humans. Accordingly, eight patients undergoing surgical division of their accessory pathways were studied. A 56-channel (7 x 8) bipolar plaque electrode array was placed over the atrioventricular groove on the accessory pathway and atrial fibrillation electrically induced. 10 episodes of QRS transition from consecutively preexcited to nonpreexcited complexes were analyzed. This showed that consecutively preexcited QRS complexes were always associated with uniform large atrial wavefronts. Immediately prior to QRS transition, four general types of changes were observed: (a) premature invasion by secondary wavefronts creating local conduction block (n = 5); (b) wavefront collision leading to wavefront curvature (n = 2); (c) transition from a uniform large atrial wavefront to multiple fractionated small wavefronts (n = 1); and (d) uniform atrial wavefronts "marching" into the accessory pathway refractory period (n = 2). We conclude that local atrial wavefront characteristics are important factors influencing impulse propagation through the accessory pathway. The findings that local wavefront collision, curvature, or fractionation often precede loss of accessory pathway conduction support the notion that source-sink relationship is an important determinant of the safety factor for impulse propagation in the human heart. (J. Clin. Invest. 1995Invest. . 96:2284Invest. -2296

The Relative Role of Refractoriness and Source–Sink Relationship in Reentry Generation during Simulated Acute Ischemia

“…Ong et al 34 stated that the fundamental mechanisms of functional reentries lie on the source-sink relationship and Kle´ber and Rudy 26 claimed that local source-sink relationships determine the formation of propagation heterogeneities setting the stage for UDB and reentry.…”

“…This is in close agreement with the high decrease of the SF reported by other authors during severe hyperkalemia 27,40,44 and acidosis. 40,44 It is well known that the current provided by the source is reduced during rapid pacing 34 and premature stimulation, 27 so that the source-sink ratio decreases and propagation becomes difficult even leading to conduction block 27 and wavefront fragmentation. 3 Our quantification of the source-sink relationship evidenced these aspects as different SF distributions were observed when varying the CI.…”

Role of Papillary Muscle in the Generation and Maintenance of Reentry During Ventricular Tachycardia and Fibrillation in Isolated Swine Right Ventricle

“…The safety factor of impulse propagation depends on the relation between the source (amount of current available in the propagating wave front) and the sink (structure that determines current density when the wave front arrives). [1][2][3] An abrupt increase of current load (sink) may reduce the safety factor of propagation, resulting in wave break and the formation of reentry. 14,15 PM, which creates a sudden increase of muscle thickness, increases the current sink for the incoming wave front.…”

“…[1][2][3] The papillary muscle (PM) is an electrically active tissue. For an electrical impulse to propagate from the ventricle to the PM, the electrical charge it carries (source) must excite both the ventricular muscle downstream and the PM that inserts into the ventricular tissue.…”

Neural Control of Ventricular Rate in Ambulatory Dogs With Pacing-Induced Sustained Atrial Fibrillation

“…Previous studies have shown that the patterns of local atrial activation wavefronts are important in determining whether atrial activation is conducted to the ventricles via an accessory pathway. 18 The same may also be true for the AV node. Because we did not map the wavefront characteristics near the AV node, it remains unclear if the nerve activities changed wavefront characteristics and indirectly affected AV nodal conduction.…”