Simultaneous conduction over the fast and slow pathways during induction of atrioventricular nodal reentrant arrhythmia with a rate of less than 100 bpm and infra-His block after radiofrequency ablation of the slow pathway.

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal regular supraventricular tachycardia in adults. It is typically induced with an anterograde block over the fast pathway (FP) and conduction over the slow pathway (SP), with subsequent retrograde conduction over the FP. Rarely, a simultaneous conduction of a premature atrial complex occurs over the FP and SP to induce AVNRT and is called "one for two phenomenon". We present a 46-year-old woman with atrioventricular nodal rhythm with a rate of 95 beats per minute with distinct electrophysiological characteristics showing simultaneous conduction over the FP and SP during induction of tachycardia and an infra-His block after radiofrequency ablation of the SP.

Long-term results of catheter ablation in paroxysmal atrial fibrillation: lessons from a 5-year follow-up.

BACKGROUND: Paroxysmal atrial fibrillation (AF) naturally progresses toward chronic AF at an estimated rate of 15% to 30% over a 1- to 3-year period. Pulmonary vein (PV) isolation is increasingly performed for the treatment of drug-refractory paroxysmal AF. The long-term data on clinical outcome after circumferential PV isolation are limited. METHODS AND RESULTS: From 2003 to late 2004, 161 patients (121 men; age, 59.8±9.7 years) with symptomatic paroxysmal AF and normal left ventricular function underwent circumferential PV isolation guided by 3-dimensional mapping and double Lasso technique. Right-sided and left-sided continuous circular lesions encircling the ipsilateral PVs were placed with irrigated radiofrequency energy. The procedure end point was the absence of all PV spikes for at least 30 minutes after PV isolation verified by 2 Lasso catheters placed within the ipsilateral PVs. Sinus rhythm was present in 75 patients (46.6%) after the initial procedure during a median follow-up period of 4.8 years (0.33 to 5.5 years). A second procedure was performed in 66 and a third procedure in 12 patients. Recovered PV isolation conduction was observed in 62 of 66 patients (94.0%) during the second and in 8 of 12 patients (66.7%) during the third procedure. After a median of 1 (1 to 3) procedure, stable sinus rhythm was achieved in 128 of 161 patients (79.5%), whereas clinical improvement occurred in an additional 21 of 161 patients (13.0%) during a median follow-up of 4.6 years (0.33 to 5.5 years). Four patients in stable sinus rhythm died during follow-up. Progression toward chronic AF was observed in 4 patients (2.4%); however, only 2 patients reported symptoms. CONCLUSION: In patients with paroxysmal AF and normal left ventricular function, circumferential PV isolation results in stable sinus rhythm in the majority of patients, and low incidence of chronic AF was observed after ablation during up to 5 years of follow-up.

Endocardial electrogram analysis after intramyocardial injection of mesenchymal stem cells in the chronic ischemic myocardium.

BACKGROUND: Cell injection therapies have been introduced for the treatment of patients with coronary heart disease. However, intramyocardial injection of bone marrow (BM)-derived cells may generate proarrhythmogenicity. METHODS: Two weeks after the placement of a circumflex artery-ameroid constrictor, 21 pigs received mesenchymal stem cells (MSC, n = 9), mononuclear (BM)-derived stem cells (MNC, n = 6), and placebo (n = 6) using a electromechanical mapping (EMM)-guided percutaneous transendocardial injection catheter. At week 6, EMM was repeated and the injected areas were analyzed in detail to evaluate local bipolar electrogram fragmentation, duration, and amplitude. Myocardial fibrosis was evaluated by a quantitative histological analysis. RESULTS: At week 6, the injection of MSC or MNC did not increase local electrogram fragmentation (MSC group: 1.4 +/- 0.3 vs. 1.3 +/- 0.2; MNC group: 1.4 +/- 0.2 vs. 1.3 +/- 0.2; P = NS), prolong electrogram duration (MSC group: 27.1 +/- 7.8 ms vs. 23.7 +/- 2.0 ms; MNC group: 27.8 +/- 3.5 ms vs. 26.8 +/- 5.6 ms; P = NS), or decrease bipolar voltages (MSC group 2.7 +/- 0.9 mV vs. 2.8 +/- 1.0 mV; MNC group 2.0 +/- 1.0 mV vs. 1.7 +/- 0.4 mV). From week 2 to week 6, mean left ventricular ejection fraction increased in the MSC group (37.9 +/- 4.2% vs. 45.9 +/- 2.2%; P = 0.039) only. Histological analysis of the ischemic regions revealed 17.6 +/- 5% myocardial fibrosis in the MNC group vs. 13.6 +/- 3.4% MSC vs. 28.7 +/- 8.7% in the control group (P = 0.038 and P = 0.013). No death occurred in any animal after the injection procedure. CONCLUSION: Intramyocardial injection of MSC or MNC do not increase fragmentation and duration of endocardial electrograms in the injected ischemic myocardium but attenuate ischemic damage and therefore may not create an electrophysiological substrate for reentry tachycardias.

Inducibility of atrial tachyarrhythmias after circumferential pulmonary vein isolation in patients with paroxysmal atrial fibrillation: clinical predictor and outcome during follow-up.

AIMS: We investigated the presence and clinical outcome of inducibility of atrial tachyarrhythmias after circumferential pulmonary vein isolation (CPVI) in patients with paroxysmal atrial fibrillation (PAF). METHODS AND RESULTS: Sixty patients with symptomatic PAF underwent CPVI guided by 3D mapping and double Lasso technique. After achievement of CPVI, the induction was performed. The left atrium (LA) volume and the isolated LA area around the right and left-sided pulmonary veins were measured by the 3D mapping system. Sustained atrial tachyarrhythmias (>10 min) were induced after CPVI in 17 of 60 patients (28%). Patients with inducible atrial tachyarrhythmias had significantly smaller isolated areas when compared with the group with non-inducible tachyarrhythmias (16.7 +/- 2.3 vs. 18.8 +/- 2.9%, P < 0.05). After the initial procedure, recurrence occurred in 18 of 43 (42%) patients in the non-inducible group and in 7 of 17 (41%) in the inducible group during follow-up. A repeat procedure was performed in all 25 patients with recurrence. Five patients had a recurrence after the repeat procedure during 20.8 +/- 7.5 months, and there was no difference between the two groups. CONCLUSION: Inducibility of atrial tachyarrhythmias is associated with proportionally smaller isolated area and does not predict the clinical efficacy of CPVI in patients with PAF.

Catheter ablation - new developments in robotics.

Catheter ablation has become the curative treatment modality for various arrhythmias. Extending the indications for catheter ablation from simple supraventricular tachycardias to complex arrhythmias such as ventricular tachycardia or atrial fibrillation, the investigator faces prolonged procedure times, fluoroscopy exposure and the need for stable and reproducible catheter movement. Recently, remote-controlled robotic catheter ablation has emerged as a novel ablation concept to meet these requirements. This review describes the two available robotic ablation systems and summarizes their clinical applications and current human experience.