Attenuation of interatrial conduction using right atrial septal catheter ablation
David Schwartzman, MD, FACC*,
Eduardo N. Warman, PhD ,
William A. Devine, BS and
Rahul Mehra, PhD
* Atrial Arrhythmia Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
Medtronic, Inc., Minneapolis, Minnesota, USA
Department of Pathology, Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Figure 1 Endocardial view of right atrial septum. (Top) Healthy heart specimen. The territories encompassed by zones 1 and 2 are encircled. CS = coronary sinus ostium; CT = medial (septal) portion of crista terminalis; FO = oval fossa; HB = region of His bundle (apex of Koch’s triangle); IVC = inferior vena cava; RAA = medial wall of right atrial appendage; RV = septal wall of right ventricular inflow tract; SVC = superior caval vein; TV = septal leaflet of tricuspid valve. (Bottom) Postablation specimen. This subject had complete interatrial conduction block. The specimen was stained with triphenyl tetrazolium chloride, rendering "viable" myocardium deep red and ablated myocardium white.
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Figure 2 Typical surface P waves at baseline (A), after zone 1 ablation (B), after ablation of zones 1 and 2 with incomplete interatrial conduction block (C) and after ablation of zones 1 and 2 with incomplete interatrial conduction block (D). ra = component of P-wave associated with right atrial activation; la = component of P-wave associated with left atrial activation.
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Figure 3 Surface electrocardiographic, left atrial appendage (LAA) pacing stimulus artifact (PSA) and right atrial (RA) and left atrial (LA) recordings after complete interatrial conduction block. In the left half of the figure, there is no pacing. The left atrium is electrically quiescent. In the right half of the figure, LAA pacing (arrow) demonstrates left atrial capture (arrowhead), which is dissociated from the right atrium.
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Figure 4 Three surface electrocardiographic, one left atrial (LA) and two right atrial (RA) intracardiac recordings are shown during atrial fibrillation, which was induced after complete interatrial conduction block by left atrial appendage burst pacing. The right atrium is in sinus rhythm. The surface electrocardiogram manifests a "hybrid" morphology composed of both regular (arrow) and fibrillatory activity.
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Figure 5 Left atrial fibrillation, induced by left atrial appendage (LAA) burst pacing. Note that during electrocardiographic atrial fibrillation (AF), the right atrial activation rate is markedly less than the left atrial activation rate. The AF terminates (arrow), after which interatrial conduction is intact. Note also that the ventricular activation rate is significantly faster than the right atrial activation rate, consistent with activation of the atrioventricular node by a route other than the right atrium. RAA = right atrial appendage.
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