All that glitters is not gold ... all that faints is not slow.

An 82 year old man presented with multiple syncopal episodes. Since his ECG showed LBBB (left bundle branch block) with first degree AV block, he was advised permanent pacemaker implantation. However, a wide QRS tachycardia on the Holter raised the possibility of tachycardia-mediated syncope. EP (electrophysiological) studies revealed easily and repeatedly inducible short lasting slow-fast AVNRT (atrioventricular nodal reentry tachycardia) with severe hypotension. After RF ablation of the slow pathway, he is asymptomatic at six month follow-up.

Radiofrequency ablation for accessory pathways: success and variants.

INTRODUCTION: Radiofrequency ablation (RFA) is currently being advocated as the first line of therapy for symptomatic and drug refractory arrhythmias mediated by accessory pathways (APs). However, a large database on RFA for APs from India is still lacking. METHODS: Four hundred thirty-four patients (298 males, (69%)), with APs who underwent RF ablation between January, 1998 and May, 2001 were included. The success and variants were evaluated retrospectively from the data. RESULTS: The mean age was 36 +/- 11 years. There were 314 (73%) patients with WPW syndrome while the other 120 (27%) had concealed APs. Documented tachycardia was noted in 406 (91%) patients. Forty-six (11%) patients had associated structural heart disease (Ebstein's anomaly in 18). The procedure was successful in 414 (97%) of 425 patients in whom it was attempted. Of those unsuccessful, five had epicardial APs, four had multiple APs and two had immediate recurrence of APs. RFA was not attempted in nine parahissian pathways. Additional mechanisms were seen in 48 (11%) patients with WPW syndrome (14 (4.4%) AV nodal reentrant tachycardias, 16 (5%) additional concealed APs and 18 (5.7%) multiple APs). Coronary sinus diverticulum were detected in 23 (7.3%) patients, and Mahaim-like APs were diagnosed in 24 (6\8%) patients. The procedural and fluoroscopy time was 96 +/- 41 and 19 +/- 13 minutes, respectively. There were no deaths; three patients developed pericardial tamponade, which was promptly treated by pericardiocentesis. CONCLUSION: Radiofrequency ablation is a safe and effective treatment for AP mediated tachycardia, especially for younger patients and children in whom life-long drug therapy may not be best option.

Adenosine induced PR jump on surface ECG to differentiate atrioventricular nodal re-entrant tachycardia from concealed accessory pathway mediated tachycardia: a bedside test.

OBJECTIVE: To evaluate the efficacy of single dose intravenous adenosine in differentiating atrioventricular nodal re-entrant tachycardia (AVNRT) from concealed pathway mediated atrioventricular re-entrant tachycardia (AVRT) using surface ECG at the bedside. METHOD: 12 mg of adenosine was administered to 97 consecutive patients who had documented narrow QRS tachycardia without manifest pre-excitation. The test was labelled positive for AVNRT if surface ECG recordings showed signs of dual atrioventricular (AV) node physiology-namely, PR jump or AV nodal echo. The diagnostic value of this test was evaluated by electrophysiological study as the yardstick. RESULTS: The adenosine test was positive for AVNRT in 48 patients (adenosine induced PR jump in 48, AV nodal echo in 3) and negative in 49 patients. On electrophysiological study, 62 patients had AVNRT and 35 had concealed pathway mediated AVRT. Thus, the test had a sensitivity of 74% and specificity of 94%. The positive predictive value was 96% and the negative predictive value was 67%. CONCLUSION: Single dose (12 mg) intravenous adenosine administered during sinus rhythm can identify dual AV node physiology on surface ECG recording at the bedside. A positive adenosine test identified by a PR jump can differentiate AVNRT from AVRT with a high specificity and positive predictive accuracy.

Pre-excitation with syncope: a false lead?

An 18-year-old girl with pre-excitation presented with a history of recurrent syncope preceded by palpitation. The accessory pathway, which had a relatively long antegrade effective refractory period of 340 ms, was mapped and successfully ablated in the left lateral region. However, after ablation, she had reproducible sustained polymorphic ventricular tachycardia, which was found to be the cause of her syncope. Thus, alternate mechanisms of tachycardia need to be considered in patients with pre-excitation when the presentation is atypical.