Laurent Gencel

A Focal Source of Atrial Fibrillation Treated by Discrete Radiofrequency Ablation

BACKGROUND Atrial fibrillation is usually thought to be due to multiple circulating reentrant wavelets. From previous studies, a focal mechanism is considered to be very unlikely. In this report, focal atrial fibrillation is defined on an ECG pattern of atrial fibrillation and later demonstrated to be due to a focal source. METHODS AND RESULTS Nine patients (five men and four women, age, 38 +/- 7 years) with paroxysmal focal atrial fibrillation are reported here. All were free of structural heart disease and had frequent episodes of atrial fibrillation despite the use of a mean of 4 +/- 2 antiarrhythmic drugs. Atrial fibrillation was associated with runs of irregular atrial tachycardia or monomorphic extrasystoles. The electrophysiological study demonstrated that all the atrial arrhythmias were due to the same focus firing irregularly and exhibiting a consistent and centrifugal pattern of activation. Three foci were found to be located in the right atrium, two near the sinus node and one in the ostium of the coronary sinus. Six others were located in the left atrium at the ostium of the right pulmonary veins (n = 5) and at the ostium of the left superior pulmonary vein (n = 1). All atrial arrhythmias were successfully treated by use of a mean of 4 +/- 4 radiofrequency pulses. CONCLUSIONS In some patients, the surface ECG pattern of atrial fibrillation is due to a focal rapidly firing source of activity that can be eliminated by discrete radiofrequency energy applications.

Radiofrequency catheter ablation of common atrial flutter in 80 patients.

OBJECTIVES The purpose of this study was to evaluate the efficacy and safety of radiofrequency catheter ablation of common atrial flutter and to determine the optimal target sites in a large series of patients. BACKGROUND Recent studies report the efficacy of radiofrequency current application in the low right atrial region to interrupt and prevent recurrences of common atrial flutter. However, larger groups of patients are required to confirm the efficacy of this technique and to specify the target sites. METHODS Two different approaches were used to target the ablation site in 80 consecutive patients. In the first 50 patients, target sites were localized using both anatomic landmarks and electrophysiologic variables. Three anatomic landmarks were used: area 1 = between the tricuspid valve and inferior vena cava orifice; area 2 = between the tricuspid valve and coronary sinus ostium; area 3 = between the inferior vena cava and coronary sinus. The electrophysiologic criterion was to ablate when there was a stable atrial electrogram during the plateau phase. In the next 30 patients we assessed the effect of application of radiofrequency energy in a single line in area 1, 2 or 3 in groups of 10 patients. RESULTS Overall atrial flutter was interrupted and rendered noninducible after a single session in 72 patients (90%) and could not be interrupted in 8 (10%). The mean (+/- SD) number of radiofrequency applications was 12 +/- 8. After a mean (+/- SD) follow-up of 20 +/- 8 months, recurrences occurred in 14 patients (17%). The location of the final successful site in the first group of 50 patients was in area 1 in 39%, area 2 in 36% and area 3 in 25%. In the next 30 patients, when lines of radiofrequency lesions were placed at several sites, they produced success rates of 70%, 40% and 10% at areas 1, 2 and 3, respectively. CONCLUSIONS Radiofrequency catheter ablation of atrial flutter can be performed with a high success rate and is safe. The highest success rate is achieved with radiofrequency energy applied in the isthmus between the inferior vena cava orifice and tricuspid valve.

Characteristics of the Ventricular Insertion Sites of Accessory Pathways With Anterograde Decremental Conduction Properties

BACKGROUND Accessory pathways (APs) with anterograde decremental conduction properties referred to as Mahaim fibers have recently been recognized as originating from the right lateral atrium. Little information is available about their distal insertion. The purpose of this study was to determine the different kinds of APs involved and the characteristics of their distal insertion site. METHODS AND RESULTS Twenty-one patients (mean age, 28 +/- 13 years) with reciprocating tachycardia or atrial fibrillation were studied. Right-sided atrial and/or ventricular endocardial mapping during tachycardia identified different types of APs. (1) Seventeen patients had long APs originating from the right lateral atrium and coursing several centimeters to the right ventricle. In 10 patients, the AP terminated in or close to the right bundle-branch system (atriofascicular AP) and in 7, the AP terminated in the anterior right ventricle (atrioventricular AP). Patients with atriofascicular APs had narrower QRS complexes (133 +/- 10 versus 165 +/- 26 milliseconds, P = .02) and narrower initial r wave in leads V2 through V4 during maximal preexcitation than patients with atrioventricular APs. In addition, they had earlier His-bundle and right bundle-branch retrograde activation, ie, shorter V-His (16 +/- 5 versus 37 +/- 9 milliseconds, P < .01) and V-right bundle intervals (3 +/- 5 versus 25 +/- 6 milliseconds, P < .01). In 6 patients, minimal preexcitation not readily apparent was present in sinus rhythm despite the appearance of a narrow QRS complex. A wide distal insertion site of 0.5 to 2 cm in diameter consistent with arborization of the AP was found in 10 patients. The distal application of radiofrequency current produced a change in the preexcitation pattern in 4 patients and ablated the AP in 2 patients. In the other patients, radiofrequency current was applied more proximally and successfully ablated the AP bundle (n = 9) or AP proximal insertion (n = 6). No recurrence was observed during a follow-up period of 12 +/- 10 months. (2) Four patients had short paratricuspid atrioventricular APs; in one, the decremental conduction property was acquired as demonstrated by two electrophysiological studies performed 7 years apart. Radiofrequency ablation was successfully accomplished in all 4 patients at the tricuspid annulus. CONCLUSIONS Different types of APs account for tachycardias previously called Mahaim fibers. Long and short atrioventricular APs are observed in 81% and 19%, respectively. Long APs often have a distal arborization and may have either a fascicular or ventricular insertion. Radiofrequency current is more efficient when applied to the AP bundle or AP proximal insertion rather than to the distal insertion in patients with long APs.

Electrocardiographic characteristics and catheter ablation of parahissian accessory pathways.

BackgroundAccessory pathways may be located in close proximity to the His bundle, resulting in a high risk of heart block during attempted surgical or electrical interruption of these pathways. This study reports the prevalence, ECG characteristics, and results of catheter ablation of parahissian accessory pathways. They were defined on the basis of both the presence of a high amplitude (>0.1 mV) of His bundle potential at the ablation site and an exclusion of anteroseptal or midseptal location of the accessory pathway. Methods and ResultsEight patients with a parahissian accessory pathway were identified among 582 consecutive patients who underwent radiofrequency ablation of an acces-sory pathway. They were six males and two females with a mean age of 21±9 years. During maximal preexcitation, the ECG showed a positive delta wave in leads I, II, and aVF in all patients: six had a negative delta wave in leads V1 and V2 instead of the positivity usually observed in anteroseptal accessory pathways. This pattern had a sensitivity of 75%, a specificity of 96%, a positive predictive value of 86%, and a negative predictive value of 93% for a parahissian location in comparison with a group of 28 patients with anteroseptal accessory pathways. At the successful ablation site, the mean amplitude of the His bundle potential was 0.2±0.1 (0.12 to 0.4 mV). All accessory pathways were successfully ablated without causing heart block using 5 to 20 W of radiofrequency energy. ConclusionsParahissian accessory pathways have a preexcitation pattern that is distinctive from that of anteroseptal accessory pathways. Catheter ablation of these pathways is feasible using low energy with preservation of normal atrio-ventricular conduction.

Causes of Syncope in Patients with Alzheimer’s Disease Treated with Donepezil

IntroductionTreatment of Alzheimer’s disease (AD) with cholinesterase inhibitors carries a theoretical risk of precipitating bradycardia. Though syncope occurs in patients with AD, its aetiology is unclear. The aim of this study was to determine the causes of syncope in patients with AD who were treated with donepezil and hospitalised for evaluation of syncope.MethodsWe studied 16 consecutive patients (12 women, 4 men) with AD aged 80 ± 4 years who were hospitalised for evaluation of syncope. All patients underwent staged evaluation, ranging from physical examination to electrophysiological testing.ResultsThe mean dose of donepezil administered was 7.8 mg/day, and the mean duration of donepezil treatment at the time of syncope was 12 ± 8 months. A cause of syncope was identified in 69% of patients. Carotid sinus syndrome was observed in three patients, complete atrioventricular block in two patients, sinus node dysfunction in two patients, severe orthostatic hypotension in two patients and paroxysmal atrial fibrillation in one patient. A brain tumour was discovered in one patient. No cause of syncope was found in 31% of patients despite comprehensive investigation. Repetition of the investigations after discontinuation of donepezil was noncontributory.ConclusionIn patients with AD treated with donepezil, a noninvasive evaluation identified a probable cause of syncope in over two-thirds of patients. Cardiovascular abnormalities were predominant. Noninvasive evaluation is recommended before discontinuing treatment with cholinesterase inhibitors in patients with AD and unexplained syncope.

Cardiovascular effects and risk of syncope related to donepezil in patients with Alzheimer's disease.

AbstractBackground: When otherwise unexplained, syncope in patients with Alzheimer’s disease may be attributed to bradycardia caused by cholinesterase inhibitors. We studied prospectively the clinical events and cardiovascular changes occurring during treatment with donepezil in patients with Alzheimer’s disease. Methods: Consecutive patients presenting with mild-to-moderate Alzheimer’s disease were included in the study. Their clinical characteristics, blood pressure, heart rate and electrocardiogram were recorded before (baseline) and during treatment with donepezil. The drug was administered at a dosage of 5 mg/day for 1 month and 10 mg/day for the following 7 months, as tolerated. We compared the baseline observations with those made at 1, 2 and 8 months of donepezil treatment. We also examined the effects of negatively chronotropic or dromotropic drugs concomitantly administered with donepezil. Results: Thirty patients were included in the study, of whom 43% were taking negatively chronotropic or dromotropic drugs. The first month of therapy (donepezil 5 mg/day) was completed by 26 patients. During the 7-month high-dosage phase (10 mg/day), four patients dropped out of the study; thus, 22 patients completed the full 8 months of the study.The mean heart rate was 66 ± 8 beats/min at baseline in the overall study population. This decreased significantly to 62 ± 9, 61 ± 7 and 62 ± 8 beats/min at the 1, 2 and 8 month timepoints, respectively (all p = 0.002 vs baseline). Among patients not receiving negatively chronotropic or dromotropic drugs, heart rate decreased significantly over the course of the study (from 67 ± 8 beats/min at baseline to 62 ± 8 beats/min at 1 month, 62 ± 7 beats/min at 2 months and 62 ± 8 beats/min at 8 months [all p = 0.005 vs baseline]). There was no significant change in heart rate in patients who were receiving negatively chronotropic or dromotropic drugs.The PR interval increased over the course of the study in all patient groups, but these changes were only statistically significant in the group of patients who were not taking negatively chronotropic or dromotropic drugs (155 ± 23ms at baseline vs 158 ± 21, 160 ± 22 and 163 ± 24ms at the 1, 2 and 8 month timepoints; all p = 0.02 vs baseline).One patient developed syncope due to orthostatic hypotension; there were no cases of bradycardia-induced syncope. Gastrointestinal manifestations were reported in ten of the study patients. Abdominal pain and vomiting were the reasons for study termination in five of the eight patients who did not complete the trial. Conclusion: A donepezil-induced decrease in heart rate and increase in PR interval were observed only in patients with Alzheimer’s disease who were not treated with negatively chronotropic or dromotropic drugs. These changes were not associated with bradycardia-induced syncope.

Ventricular Protection Against Atrial Arrhythmias in DDD Pacing Based on a Statistical Approach: Clinical Results

Atrial arrhythmias (AA) are commonly encountered in DDD paced patients. Newer dual chamber pacemakers (PM) possess mode switching functions that convert pacing to an asynchronous mode when AAs are detected. The lack of a reliable mode switch leading to rapid, irregular ventricular responses may result from AA undersensing. To avoid this, the DDDR PM Chorum 7234 Eta Medical AA diagnosis is based on a statistical approach: the PM constantly compares arrhythmic and sinus cycles and, based on “strong” and “weak” criteria, provides for rapid or slower mode switch. The aim of the study was to evaluate the efficiency and reliability of these two criteria. Thirty‐one patients with a Chorum 7234 implanted for AV block (11), sinus dysfunction (10), both (5), or hypertrophic obstructive cardiomyopathy (5) were evaluated at 24 hours and 1 month using the internal memory (IM) of the PM, surface 24‐hour Holter recordings, and exercise testing. Interrogation of the IM on the first day of study showed that 8 patients had mode switching episodes, based only on the strong criterion confirmed by the surface Holter recording. At I month, the IM revealed mode switching episodes in 12 patients, 6 of whom had used the weak criterion. No inappropriate mode switching episode was recorded during exercise testing at the 1‐month follow‐up. These results confirm the reliability and efficiency of this algorithm as well as the requirement for a specific algorithm to compensate for transient loss of sensing during AA.

Scoring Method for Assessing Rate Adaptive Pacemakers: Application to Two Different Activity Sensors

To optimize programming of rate adaptive pacemakers (RAPs), we explored a new mathematical method to assess the performance of RAPs during daily‐life tests, using customized Windows‐based software. By stepwise discriminant analysis and linear regression, this method allows calculation of the acceleration and deceleration capacity of pacemakers and their general behavior during effort and recovery phases. Twenty‐three patients (10 females and 13 males; 68 ± 8 years) with chronic atrial fibrillation and a slow ventricular response were evaluated. They randomly received an accelerom‐eter‐controlled VVIR Dash Intermedics pacemaker (10 patients) or a vibration piezoelectric‐controlled WIR Sensolog III Siemens pacemaker (13 patients). All patients underwent the same test protocol: 6 minutes walking, 1.5 minutes climbing stairs, 1.5 minutes descending stairs, and 0.5 minutes sit‐ups. By definition, the pacemaker responsiveness slope was programmed so that the heart rate response of paced patients during the walking test corresponded best to that of healthy controls. The slope was left unchanged for the other tests. We considered four scores: an acceleration score (EA score), an effort rate score (ER score), a deceleration score (RD score), and a recovery rate score (RR score). Scores ranged from 10 (hypochronotropic behavior of the pacemaker) to +10 (hyperchronotropic behavior), based on daily‐life tests of 15 healthy controls (7 females and 8 males, 65 ± 9 years). A score of 0 represented exact concordance with healthy controls. During stair descent, the Sensolog III produced excessive acceleration (EA score =+2.9 ± 1.1) compared to: (1) stair climbing (EA score =−4.0 ± 1.9; P = 0.01, with the same pacemaker); and (2) the Dash (+1.8 ± 1.9; P = 0.04) and healthy controls (P = 0.02). The sit‐up tests revealed a hypochronotropic response of both pacemakers compared to healthy controls, with a larger difference for the Sensolog III (EA score =−2.0 ± 5.8; P = 0.04; RD score =−6.8 ± 3.8; P = 0.02). We conclude that activity‐driven pacemakers can accommodate brief activities, except for isovolumetric exercise such as sit‐ups. During daily activities, accelerometer‐driven pacemakers seem to provide a heart rate response closer to that of healthy controls. Our new mathematical analysis is a simple and reproducible method for evaluating and quantifying the efficacy of any sensor‐driven pacemaker.

Long‐Term Survival After Closed‐Chest His‐Bundle Ablation with DC Shock for Supraventricular Arrhythmias: A 10‐Year Experience with 317 Consecutive Patients

Survival after closed‐chest ablation of His bundle with DC shock for supraventricular arrhythmias was analyzed for a 10‐year period (May 1982‐December 1992) with 317 consecutive patients (167 males, 150 females; mean age 66 years; range 33–93 years). Of these, 54 patients died (17.3%) and 5 were lost to follow‐up. The mean age at ablation was 70.3 ± 8.3 years with a range of 49–93 years. Of those who died, the mean survival was 30.5 ± 28.6 months with a range of 36 hours to 120 months; the diagnosis of heart disease was; hypertension (n = 14), cardiomyopathy (n = 8), ischemic (n = 7), valvular (n = 6). Cor pulmonale (n = 3), valvular and ischemic (n = 2). hypertension and ischemic (n = 1), miscellaneous (n = 3), and none (n = 10). Of the patients who died after ablation, the arrhythmias at the time of the ablation were atrial fibrillation (AF; n = 33), sick sinus syndrome (n = 5), atrial flutter (AFL; n = 4), paroxysmal AV junctional tachycardia (PAVJT; n = 4), AF + AFL (n = 4), atrial tachycardia (n = 2). PAVJT + AFL (n = 1), and AF + AFL + atrial tachycardia (n = 1). Death was sudden in 13 patients (25%), due to heart failure in 10 (19.2%), myocardial infarction in 4 (7.7%), stroke in 4 (7.7%). aortic vascular accident in 3 (5.8%), miscellaneous in 18 (34.6%), and undetermined in 2. The overall survival rate was 94.5% at 1 year (n = 256), 80.1% at 5 years (n = 88), 72.8% at 8 years (n = 20), and 51% at 10 years (n = 4); patients with no underlying heart disease had a better survival. DC ablation of the His bundle was not associated with a high short‐ or long‐term mortality. This study may serve as a historical review with which to compare closed‐chest ablation of the His bundle with that of other energy sources such as radiofrequency energy.