Abstract 19013: Symptomatic Spontaneous Automaticity in a Decrementally Conducting Left Free Wall Accessory Pathway in a Patient With Congenital Heart Block
Introduction: A 20 year-old female with a history of a coil-occluded patent ductus arteriosus and congenital complete atrioventricular (AV) block was admitted for a wide complex tachycardia (WCT) associated with palpitations and dizziness. Her LV function was normal and no additional structural heart disease was noted on a cardiac MRI. Electrophysiology (EP) study was performed.
Results: EP study showed sinus tachycardia with 1:1 antegrade conduction via a left-sided accessory pathway. The accessory pathway demonstrated decremental conduction, adenosine responsiveness, and no retrograde conduction. The earliest ventricular activation was noted in the distal coronary sinus electrode. At slower atrial rates (70-100 bpm), there was isorhythmic dissociation (see figure) between the accessory pathway (QRS identical to maximal pre-excitation) and the sinus node strongly suggesting spontaneous accessory pathway automaticity. The accessory pathway was successfully ablated by targeting an accessory pathway potential located at the anterior aspect of the mitral valve. Post-ablation, there was complete AV block with a narrow junctional escape rhythm at a rate of 64 beats per minute. The patient underwent placement of a dual chamber pacemaker.
Conclusion: This is, to our knowledge, the first reported case of a left-sided accessory pathway with both spontaneous automaticity and Mahaim-like properties.
- © 2013 by American Heart Association, Inc.