Complex Manifestations of an Automatic Mode Switching Algorithm
S. Serge Barold, Roland X. Stroobandt · Pacing and Clinical Electrophysiology · 2007
cardiac pacing, atrial flutter, automatic mode switching Case PresentationA 63-year-old man presented with a history of hypertension, a previous stroke, and five episodes of atrial flutter requiring electrical cardioversions from 1997 to 2001.He had also sustained only one brief episode of atrial fibrillation.He was treated with long-term coumadin and unsuccessfully with amiodarone for 6 months.This was followed by unsuccessful therapy with propafenone, flecainide, sotalol, and lisinopril.In 2001 ablation of common atrial flutter was performed with resultant bilateral cavotricuspid isthmus block.The patient remained stable until October 2005 when he presented with atypical atrial flutter (ventricular rate 156 bpm) which was electrically cardioverted to sinus rhythm.However, the patient refused a second atrial flutter ablation with a left-sided approach.In March 2006, further episodes of atrial fibrillation and atrial flutter (ventricular rate = 112 bpm on medications) precipitated congestive heart failure.The left ventricular ejection fraction was 39%.After cardioversion to sinus rhythm, the patient agreed only to ablation of the atrioventricular (AV) node and pacemaker implantation.Consequently he first received a Medtronic Enpulse DDDR pacemaker (Minneapolis, MN, USA) programmed to a lower rate of 80 ppm with the intent of performing AV nodal ablation (AV nodal ablation at a later date if atrial flutter recurred).About 3 weeks later, the patient was seen after the development of recurrent atrial flutter lasting for at least 2 days and Figure 1 was recorded.Table I outlines the programmed parameters of the pacemaker when Figure 1 was registered.Interrogation of the pacemaker revealed no memorized episodes of automatic mode switching since implantation.As = atrial sensed event, AR = atrial sensed event in the pacemaker atrial refractory period, VS = ventricular sensed event.The postven-