Home  About us  Contact
 

Atrial Electrodes (atrial + electrode)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Orthodromic Pacemaker-Mediated Tachycardia in a Biventricular System Without an Atrial Electrode

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2004
ANTONIO BERRUEZO M.D.
Pacemaker-mediated tachycardia is a well-known complication of dual-chamber devices. In this report, we describe for the first time a case of orthodromic pacemaker-mediated tachycardia in a patient in whom a biventricular system without an atrial electrode had been implanted. Retrograde atrial activation was directly produced by the dislodged coronary vein electrode in the AV groove, resulting in simultaneous capture of the left atrium and left ventricle. During tachycardia, AV nodal conduction was via the anterograde pathway of the circuit and limited the ventricular response. Subsequently, right ventricular activation was sensed by the right ventricular electrode that triggered biventricular pacing and left atrial capture, perpetuating the tachycardia. Because the left atrial threshold was higher than the left ventricular threshold, the problem could be resolved easily by lowering the output of the coronary vein electrode. [source]

Centrifugal Gradients of Rate and Organization in Human Atrial Fibrillation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2009
DAVID E. KRUMMEN M.D.
Introduction:Animal studies show that atrial fibrillation (AF) may emanate from sites of high rate and regularity, with fibrillatory conduction to adjacent areas. We used simultaneous mapping to find evidence for potential drivers in human AF defined as sites with higher rate and regularity than surrounding tissue. Materials and Methods:In 24 patients (age 61 ± 10 years; 12 persistent), we recorded AF simultaneously from 32 left atrial bipolar basket electrodes in addition to pulmonary veins (PV), coronary sinus, and right atrial electrodes. We measured AF cycle length (CL) by Fourier transform and electrogram regularity at each electrode, referenced to patient-specific atrial anatomy. Results:We analyzed 10,298 electrode-periods. Evidence for potential AF drivers was found in 11 patients (five persistent). In persistent AF, these sites lay at the coronary sinus and left atrial roof but not PVs, while in paroxysmal AF six of nine sites lay at PVs (P < 0.05). During ablation, a subset of patients experienced AF CL prolongation or termination with a focal lesion; in each case this lesion mapped to potential driver sites on blinded analysis. Conversely, sequential mapping failed to reveal these sites, possibly due to fluctuations in dominant frequency at driver locations in the context of migratory AF. Conclusions:Simultaneous multisite recordings in human AF reveal evidence for drivers that lie near PVs in paroxysmal but not persistent AF, and were sites where ablation slowed or terminated AF in a subset of patients. The future work should determine if real-time ablation of AF-maintaining regions defined in this fashion eliminates AF. [source]

DDD Pacemaker Implantation After Fontan-Type Operations

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003
MARKUS K. HEINEMANN
HEINEMANN, M.K., et al.: DDD Pacemaker Implantation After Fontan-Type Operations.Bradyarrhythmias developing after Fontan-type operations impair the function of the univentricular heart causing fatigue, headaches, ascites, and protein-losing enteropathy (PLE). Transvenous inaccessibility, requiring epicardial implantation, accounts for the reluctance to implant a pacemaker (PM). Between 1997 and 2000, 24 patients (mean age 9.5 years, range 6 months to 19 years) with Fontan-type operations received DDD pacing systems with atrial steroid-eluting stitch-on electrodes (mean capture threshold 1.9 V/0.5 ms, range 0.4,3.5 V) and ventricular screw-in electrodes (mean capture threshold 1.7 V/0.5 ms, range 0.1,3 V). The systems were implanted at the time of conversion from atrio- to cavopulmonary connections in 5 patients, at the time of a total cavopulmonary Fontan operation in 6, and 1,50 months thereafter (mean = 18) in 13 patients. A right ventricular anatomy was present in 13 (54%) of 24 of PM recipients, versus 35% of the overall population. After a mean follow-up of 3.5 years, the PM were functioning in DDD mode in 23 of the 24 patients. Length of hospital stay in the ten patients who underwent repeat sternotomy was 5 days, without procedure related complications. In three children a repeat sternotomy was avoided by implanting the atrial electrodes during the Fontan operation. All patients improved clinically, including resolution of PLE in four patients. Bradyarrhythmias may lead to significant morbidity after Fontan-type operations. Electrophysiological evaluation is advised at follow-up. The indication for implantation of a DDD pacemaker system should be liberal. Placing atrial electrodes during the Fontan operation, especially in the presence of a right ventricular anatomy, avoids repeat sternotomy. (PACE 2003; 26[Pt. II]:492,495) [source]