Chrome congestive heart failure: Radiofrequency ablation of accessory pathways: implications of accumulated experience and time dedicated to procedures

Previous reports on radiofrequency ablation of accessory pathwayshave shown that the experience of the operator is of crucialimportance in reducing fluoroscopy time and achieving highersuccess rates. However, a detailed analysis of this importantissue has not been previously attempted We analysed 71 consecutive ablation procedures undertaken atSt George's Hospital by the same electrophysiology group andalways with the same first operator. Of all procedures, 66 (916%)were successful, as judged by abolition of accessory pathwayconduction without recurrence within the next 24 h. Failuresincluded two out of 38 left-sided pathway procedures (5·3%),one out of 11 intermediate septal (9·1%) and four outof 22 right-sided pathway procedures (18·2%). These differencewere not statistically significant. Average procedure and screeningtimes for all procedures were 162·9±86·0min and 56·8±48·2 mm respectively, whereasthe median of the number of discharges was 12, ranging fromone to 51. There was no significant difference between pathwaygroups or between concealed and non-concealed pathways in respectto procedure and screening time or number of discharges. Therewas a significant tendency towards decreased procedure and screeningtimes with accwnulating experience and this was similar forall pathway groups. There was also a tendency towards improvedcwnulative success rates with time dedicated to procedures. We conclude that a certain amount of ablation experience isrequired, even by experienced electrophysiologists, before arelatively high success rate without long radiation exposurecan be achieved, regardless of the location or the mode of conductionof the pathway. Success rates increase with procedure time,suggesting that early abandonment of the procedure may resultin higher failure rates in diffcult cases.     

Influence of Propranolol on the Ventricular Depolarization Gradient

Sensing of the ventricular depolarization gradient (VDG) has recently been used as The basis of a closed-loop rate responsive pacemaker. Factors influencing this aspect of the evoked response have not been fully evaluated although previous reports have suggested that sympathetic stimulation and circulating catecholamines are primarily responsible for the observed changes during stress and exercise. In five patients (Table I), four males and one female (mean age 60.4 ± 20.1 years) implanted with the Prism pacemaker, the pacing response to exercise and tilting was assessed before and after the infusion of propranolol. There was an increase in the pacing rate in all patients during the infusion of the drug (mean 27 ± 12.9 beats/min) suggestive of a direct drug effect on the VDG. The rate control parameter (RCP) of the pacemaker, the numerical equivalent of the VDG, was significantly different after the administration of propranolol (P < 0.01). However, exercise performance and pacing rate behavior were not different after beta blockade. The pacing rate increase observed when tilting patients to the supine position was not altered by propranolol. Out date suggest that factors other than adrenergic stimulation may be of importance in affecting the ventricular evoked response and accordingly the rate adaptation of the Prism pacemaker.     

Electrophysiological Effects of E 4031, a Drug with Selective Class III Properties, in Man

We studied the electrophysiological effects ofE 4037, given in a dose ascending manner (1.5, 3.0, and 6.0 μg/kg over 5 min followed by 0.1, 0.2, and 0.4 μg/kg per min for 60 min, respectively) to 19 volunteers. There were significant, dose related linear increases in QT and QT_C intervals, in atrial functional and effective refractory periods (ERPs) at a paced cycle length of 400 ms, and in ventricular functional and ERPs at a paced cycle length of 600 ms. There was no significant change in the AH and HV intervals or QRS duration. No significant proarrhythmic or other side effects were encountered during the administration of the drug. E 4031 prolongs atrial and ventricular refractoriness without significantly affecting AV or intraventricular conduction, consistent with selective Class III properties. At the doses used in the present study, intravenous infusion of E 4031 appears to be safe and well tolerated.     

Recurrent Supine Syncope:

Supine Syncope. Introduction : Syncope occasionally may occur in the supine patient due to severe brady- or tachyarrhythmia. However, recurrent syncope upon assumption of the supine position as a result of a neurally mediated reflex mechanism has not been reported previously.
Methods and Results : Two young patients, both of whom had significant systemic illnesses, experienced recurrent episodes of presyncope and/or syncope shortly after assuming the supine position. During ambulatory ECG monitoring, symptoms were provoked only by lying down and were associated with transient bradycardia. Head-up tilt table testing was undertaken as part of the syncope evaluation and was nondiagnostic in both cases. However, both patients exhibited a transient cardioinhibitory response with reproduction of typical symptoms upon return of the table to the supine position ("reverse tilt"). During follow-up (8 and 14 months), both patients improved with pharmacologic treatment (disopyramide in one case and midodrine in the other).
Conclusion : Presyncope or syncope upon lying down can he an unusual manifestation of the neurally mediated faint.     

Prehospital Discharge Defibrillation Testing in ICD Recipients: A Prospective Study Based on Cost Analysis

Prehospital discharge defibrillation testing is often performed to verify the function of newly implanted cardioverter defibrillators (ICDs). To determine whether elimination of predischarge testing could reduce costs without placing patients at additional risk, 31 patients were randomized in this prospective clinical evaluation to either receive or not receive a predischarge ICD defibrillation test. Expenses associated with postimplant care was the primary endpoint. All patients underwent induction of ventricular fibrillation after 6 months to evaluate ICD function. The groups were well matched in terms of patient characteristics, initial lead implant parameters, and defibrillation thresholds. Elimination of prehospital discharge testing resulted in a savings of $1,800/patient after 6 months, with no difference between groups in terms of ICD complication rates or unanticipated hospital admissions. Further studies are needed to better define the most appropriate time to assess defibrillation thresholds in the first year after implantation.     

Left Atrial Ablation at the Anatomic Areas of Ganglionated Plexi for Paroxysmal Atrial Fibrillation

Background: Modification of left atrial ganglionated plexi (GP) is a promising technique for the treatment of paroxysmal atrial fibrillation (AF) but its therapeutic efficacy is not established. This study aimed at evaluating the effectiveness of anatomic GP modification by means of an implantable arrhythmia monitoring device. Methods: In 56 patients with paroxysmal AF, radiofrequency ablation at anatomic sites, where the main clusters of GP have been identified in the left atrium, was performed. In all patients, an electrocardiogram monitor (Reveal XT, Medtronic Inc., Minneapolis, MN, USA) was implanted before (n = 7) or immediately after (n = 49) AF ablation. Results: Average duration of the procedure was 142 ± 18 min and average fluoroscopy time 20 ± 7 min. In total, 53–81 applications of RF energy were delivered (mean of 18.2 ± 3.8 at each of the four areas of GP ablation). Heart rate variability was assessed in 31 patients. Standard deviation of RR intervals over the entire analyzed period, the root mean square of differences between successive RR intervals, and high frequencies decreased, while HRmin, HRmean, and LF to HF ratio increased immediately postablation; these values returned to baseline 6 months after the procedure. At end of 12‐month follow‐up, 40 (71%) patients were free of arrhythmia recurrence. Ten patients had AF recurrence, two patients had left atrial flutter, and four patients had episodes of flutter as well as AF recurrence. Duration of episodes of AF after ablation gradually decreased over the follow‐up period. Conclusions: Regional ablation at the anatomic sites of the left atrial GP can be safely performed and enables maintenance of sinus rhythm in 71% of patients with paroxysmal AF for a 12‐month period. (PACE 2010; 33:1231–1238)