Radiofrequency Catheter Ablation of Left Atrial Tachycardia Originating Within the Pulmonary Vein in a Patient with Dextrocardia

A case is presented of a 38-year-old male with dextrocardia in whom radiofrequency current ablation of an incessant atrial tachycardia originating within the infero-lateral pulmonary vein was achieved. Activation mapping with detection of the earliest atrial activation was used for identification of the arrhythmogenic focus. In addition to fluoroscopy, trans- esophageal echocardiography was used for catheter guidance during the transseptal puncture. The present experience suggests that location of an arrhythmogenic focus within the pulmonary venous system should be considered whenever early atrial activation during ectopic atrial tachycardia is recorded at the junction between thfi left atrium and the pulmonary veins.     

Nonfluoroscopic Localization of an Amagnetic Catheter in a Realistic Torso Phantom by Magnetocardiographic and Body Surface Potential Mapping

This study was performed to evaluate the accuracy of multichannel magnetocardiographic (MCG) and body surface potential mapping (BSPM) in localizing three-dimensionally the tip of an amagnetic catheter for electrophysiology without fluoroscopy. An amagnetic catheter (AC), specially designed to produce dipolar sources of different geometry without magnetic disturbances, was placed inside a physical thorax phantom at two different depths, 38 mm and 88 mm below the frontal surface of the phantom. Sixty-seven MCG and 123 BSPM signals generated by the 10 mA current stimuli fed into the catheter were then recorded in a magnetically shielded room. Non-invasive localization of the tip of the catheter was computed from measured MCG and BSPM data using an equivalent current dipole source in a phantom-specific boundary element torso model. The mean 3-dimensional error of the MCG localization at the closer level was 2 ± 1 mm. The corresponding error calculated from the BSPM measurements was 4 ± 1 mm. At the deeper level, the mean localization errors of MCG and BSPM were 7 ± 4 mm and 10 ± 2 mm, respectively. The results showed that MCG and BSPM localization of the tip of the AC is accurate and reproducible provided that the signal-to-noise ratio is sufficiently high. In our study, the MCG method was found to be more accurate than BSPM. This suggests that both methods could be developed towards a useful clinical tool for nonfluoroscopic 3-dimensional electroanatomical imaging during electrophysiological studies, thus minimizing radiation exposure to patients and operators.     

Improvement of Quality of Life by Means of Antitachy Pacing: From PainFREE to the ADVANCE-D Trial

Background: Implantable cardioverter-defibrillators (ICD) can terminate ventricular tachyarrhythmias with shocks (painful) or antitachycardia pacing (painless). According to the results of the Pacing Fast VT Reduces Shock ThErapies Trials, antitachycardia pacing (ATP) can avoid painful shocks and also increase device longevity. The purpose of the ADVANCE-D (Atp DeliVery for PAiNless ICD ThErapy) study is to determine the most appropriate ventricular tachycardia (VT) therapy, so as to optimize painless therapy for life-threatening arrhythmias.
Methods and Results: The ADVANCE-D is a prospective, multicenter, parallel, two-arm randomized study designed to evaluate the efficacy of two different sequences of ATP therapies (burst 15 pulses, 88%, vs burst 8 pulses, 88%), during an episode of spontaneous arrhythmia classified as fast VT (FVT) in patients with a Class I or IIA indication for ICD implantation (single and dual chamber devices). The primary endpoint is to compare the efficacy of two ATP therapies for FVT episodes. The study will enroll a minimum of 900 patients within 2 years, followed-up for 12 months. The investigation is expected to be completed in 2007.
Conclusions: The ADVANCE-D trial is the first large randomized clinical investigation aimed to evaluate optimal programming and efficacy of ATP.     

The "SPEM" (Studio Policentrico Elettrocateteri Membrane): A Multicenter Study on Membrane Leads

SPEM is a multicenter randomized double-blind study performed to test the acute and chronic electrophysiological behavior of three different ventricular leads: (1) an ion exchange membrane with 30-μg dexamethasone elution in a contoured activated carbon tip lead (Membrane 1400T, 30 patients); (2) the same lead design without steroid (Membrane 1401T, 24 patients); and (3) the same lead design without steroid or membrane (control group, 27 patients). Twenty-three of the 81 patients were women; the mean age for all patients was 74 ± 10 years. Parameters are calculated both in uni- and bipolar configuration at implant and at follow-up after 1, 5, 15, 30, 90, 180, and 360 days. Implant threshold (chronaxie = 0.413 ± 0.280 ms, rheobase = 0.264 ± 0.099 V), signal amplitude (13.45 ± 5.87 mV), and slew rate (2.05 ± 1.38 V/s) reveal no significant differences. Pacing impedance values both at implant (unipolar 571 ± 165 Ω; bipolar 605 ± 123 Ω) and at follow-ups (unipolar 480 ± 72 Ω; bipolar 518 ± 75 Ω) are slightly lower in the unipolar configuration. At 15 and 30-day follow-ups, control group and nons-teroid leads show a higher threshold value growth (in unipolar from 0.16 ± 0.11 to 1.19 ± 0.85 μJ; in bipolar from 0.18 ± 0.13 to 1.24 ± 0.88 μJ) than the membrane steriod leads (in unipolar from 0.13 ± 0.11 to 0.70 ± 0.39 μJ; in bipolar from 0.23 ± 0.32 to 0.76 ± 0.36 μJ); the threshold of nonsteroid leads decreases after 1–3 months and it settles at the same threshold level of the leads with membrane and steroid (in unipolar 0.60 ± 0.33 ±J; in bipolar 0.55 ± 0.26 μJ), which has been stable since the first month. The ion exchange membrane is effective in reducing the chronic pacing threshold like acute steroid elution at low doses, but membrane alone does not prevent an acute pacing threshold increase through the first month postimplant.