[Identification of candidates for multisite pacing: results and presumed mechanisms of action after five years experience]. / Identification des patients candidats a la stimulation multisite. Résultats et mécanismes d'action supposés a l'issue d'une expérience monocentrique de 5 ans.

Biventricular resynchronisation is an additional therapeutic option in the management of refractory heart failure, with a functional and haemodynamic benefit as well as an improved morbidity and mortality. However, the rate of non-responsive patients has prompted a re-think about the presumed mechanisms of action for this procedure. This study aims to identify candidates more successfully. Based on five years experience in this centre, our work confirmed a medium and long term clinical benefit with multisite pacing. Nevertheless, there was evidence of a relative discordance between the functional benefit and the haemodynamic impact in terms of ejection fraction achieved with resynchronisation. While QRS narrowing appears to be a predictive factor for a successful procedure, the ECG alone is not sufficient to select 'unsynchronised' candidates. Statistical analysis reveals that before implantation the independent predictive factors to identify non-responsive patients include the presence of a complication of myocardial infarction and a low grade mitral leak. The limits of the ECG suggest a more mechanical than electrical approach to understanding the mechanisms of action for resynchronisation. Its effectiveness in cases of right bundle branch block confirm the hypothesis of left intra-ventricular conduction defects, not apparent on the surface ECG but accessible through new imaging techniques. Based on the hypothesis of delayed movement of the ventricular walls, the principle of resynchronisation aims to restore homogenous contraction. Echocardiography allows observation of electromechanical delay and opens new perspectives in the future for selecting patients for pacing. Ar

High-density mapping of activation through an incomplete isthmus ablation line.

BACKGROUND: Activation mechanisms through gaps in ablation lines and resulting electrograms are poorly understood. METHODS AND RESULTS: Eight patients (all men; age, 59+/-9 years) were studied during a recurrence of typical atrial flutter (cycle length, 233+/-19 ms) after a previous catheter ablation in the cavotricuspid isthmus. High-density 3-dimensional mapping of the isthmus was performed with the Cordis-Biosense EP Navigation system, and local conduction velocity (CV) was estimated. Maps created with 96+/-19 points revealed 0.8+/-0.3-cm gaps of recovered conduction in the ablation line. A broad wave front entered the lateral isthmus with a CV of 1.8+/-0.7 m/s, halted on the lesion line, and penetrated slowly through the gap with a CV of 0.3+/-0.1 m/s. Activation then curved and returned antidromically to activate the downstream flank of the line with a CV of 1.1+/-0.7 m/s. This front fused downstream of the line with slow transverse activation (CV, 0.4+/-0.3 m/s) parallel to it. The ablation line was demarcated by an incomplete line of convergent double potentials with isoelectric intervals (from 123+/-34 to 62+/-16 ms); each potential corresponded to local activation upstream and downstream of the lesions, while the intervening delay was produced by slow conduction through the gap combined with the progressively longer curved pathway of downstream antidromic activation as a function of distance from the gap. CONCLUSIONS: High-density isthmus mapping during recurrent flutter indicates slow conduction through gaps of recovered conduction of varying dimensions in the ablation line followed by a curved front of activation antidromically activating its downstream flank, this detour producing wide double potentials on the line.

Differential pacing for distinguishing block from persistent conduction through an ablation line.

BACKGROUND: Because complete linear conduction block is necessary to minimize the recurrence of reentrant tachycardias such as typical atrial flutter, we investigated a simple technique to recognize a persistent gap or complete linear block. METHODS AND RESULTS: We prospectively evaluated cavotricuspid isthmus conduction in 50 patients (age 63+/-8 years, 43 men) after radiofrequency ablation. The distal and proximal bipoles of a quadripolar catheter placed close to the ablation line were successively stimulated during recording from the ablation line. We hypothesized that because the initial and terminal components of local potentials reflected activation at the ipsilateral and contralateral borders of the ablation lesion, a change to a more proximal pacing site without moving the catheter would prolong the stimulus to the initial component timing, whereas the response of the terminal component would depend on the presence of block or persistent conduction. A shortening or no change in timing of the terminal component would indicate block, whereas lengthening would indicate persistent gap conduction. The results were compared with previously described criteria for isthmus block. Ninety-two sites were assessed: 17 before and 75 after the achievement of complete isthmus block. The timing of the initial component was delayed by 19+/-9 ms, and the terminal component was advanced by 13+/-8 ms after block and delayed by 12+/-9 ms in case of persisting conduction. The sensitivity, specificity, and positive and negative predictive values for linear block were 100%, 75%, 94%, and 100%, respectively. CONCLUSIONS: An accurate assessment of isthmus block or persistent isthmus conduction is possible with this technique of differential pacing.

Prospective randomized comparison of irrigated-tip versus conventional-tip catheters for ablation of common flutter.

BACKGROUND: Radiofrequency (RF) ablation of common flutter requires the creation of a complete ablation line to produce bidirectional conduction block in the cavotricuspid isthmus. An irrigated-tip ablation catheter has been shown to be effective in patients in whom conventional ablation has failed. This randomized study compares the efficacy and safety of this catheter with those of a conventional catheter for de novo flutter ablation. METHODS AND RESULTS: Cavotricuspid ablation was performed with a conventional (n=26) or an irrigated-tip catheter (n=24). RF was applied for 60 minutes with a temperature-controlled mode: 65 degrees C to 70 degrees C up to 70 W with a conventional catheter or 50 degrees C up to 50 W (with a 17-mL/min saline flow rate) with the irrigated-tip catheter. The end point was the achievement of bidirectional isthmus block, and a crossover was performed after 21 unsuccessful applications. Procedural ablation parameters as well as number of applications, x-ray exposure, procedure duration, impedance rise, and clot formation were compared for each group. A coronary angiogram was performed before and after each ablation for the first 30 patients. Complete bidirectional isthmus block was achieved for all patients. Four patients crossed over from conventional to irrigated-tip catheters. The number of applications, procedure duration, and x-ray exposure were significantly higher with the conventional than with the irrigated-tip catheter: 13+/-10 versus 5+/-3 pulses, 53+/-41 versus 27+/-16 minutes, and 18+/-14 versus 9+/-6 minutes, respectively. No significant side effects occurred, and the coronary angiograms of the first 30 patients after ablation were unchanged. CONCLUSIONS: Irrigated-tip catheters were found to be more effective than and as safe as conventional catheters for flutter ablation, facilitating the rapid achievement of bidirectional isthmus block.

Dual-loop intra-atrial reentry in humans.

BACKGROUND: Dual-loop atrial reentrant tachycardias have not been clinically described. METHODS AND RESULTS: Five patients (3 men, 2 women; mean age, 48+/-16 years) were studied 24+/-15 years after surgical closure of an ostium secundum atrial septal defect for drug-resistant atrial tachycardia. Complete tachycardia mapping was performed in the right atrium with multipolar catheters and a 3-dimensional electroanatomic mapping system (Biosense), followed by linear radiofrequency ablation of the narrowest part of each complete loop. Six tachycardias with a typical flutter morphology, a cycle length of 262+/-40 ms, and a superior f-wave axis (-77+/-11 degrees ) were mapped, 4 with a Biosense map including 106+/-32 points. Five figure-8 tachycardias had a counterclockwise loop around the tricuspid valve sharing a common anterior channel with a clockwise loop around the lateral atriotomy scar. One tachycardia was thought to have 2 counterclockwise loops around the same obstacles. Radiofrequency delivery in the cavotricuspid isthmus in each case transformed the tachycardia without any pause in a different morphology tachycardia with an inferior P-wave axis (50+/-42 degrees ) and nearly the same cycle length (272+/-39 ms) but with the periatriotomy loop alone. This arrhythmia required ablation of a second isthmus: between the lower end of the atriotomy and the inferior vena cava in 4 and the superior tricuspid annulus in 1. After a follow-up of 19+/-6 months, there were no recurrences. CONCLUSIONS: Figure-8 double-loop tachycardias mimicking the ECG pattern of a common atrial flutter occur in some patients after a surgical atriotomy. Ablation of 1 loop produces a sudden transformation to a new reentrant tachycardia formed of the remaining loop that requires ablation at a second isthmus.

Electrophysiological end point for catheter ablation of atrial fibrillation initiated from multiple pulmonary venous foci.

BACKGROUND: The end point for catheter ablation of pulmonary vein (PV) foci initiating atrial fibrillation (AF) has not been determined. METHODS AND RESULTS: Ninety patients underwent mapping during spontaneous or induced ectopy and/or AF initiation. Ostial PV ablation was performed by use of angiograms to precisely define targeted sites. Success defined by elimination of AF without drugs was correlated with the procedural end point of the abolition of distal PV potentials. A total of 197 arrhythmogenic PV foci (97%)-single in 31% and multiple in 69%-and 6 atrial foci were identified. A discrete radiofrequency (RF) application eliminated the PV potentials in 9 PV foci, whereas 2 foci from the same PV required RF applications at separate sites in 19 cases. In others, a wider region was targeted with progressive elimination of ectopy. In 49 patients, multiple sessions were necessary owing to recurrent or new ectopy. The clinical success rates were 93%, 73%, and 55% in patients with 1, 2, and > or =3 arrhythmogenic PV foci. Recovery of local PV potential and the inability to abolish it were significantly associated with AF recurrences (90% success rate with versus 55% without PV potential abolition). PV stenosis was noted acutely in 5 of 6 cases, remained unchanged at restudy, and was associated with RF power >45 W. CONCLUSIONS: Multiple PV foci are involved in initiation of AF, and elimination of PV muscle conduction is associated with clinical success.

Mapping and ablation of left atrial flutters.

BACKGROUND: Typical right atrial isthmus-dependent flutters have been described in detail, but very little is known about left atrial (LA) flutters. METHODS AND RESULTS: We performed conventional and 3D mapping of the LA for 22 patients with atypical flutters. Complete maps in 17 patients demonstrated macroreentrant circuits (n=15) with 1 to 3 loops rotating around the mitral annulus, the pulmonary veins, and a zone of block or a silent area. In 2 patients, a small reentry circuit with a zone of markedly slow conduction was identified. Linear ablation performed across the most accessible part of the circuit cured 16 patients (73%) with a follow-up of 15+/-7 months. CONCLUSIONS: LA reentrant tachycardias are related to individually varying circuits and are amenable to mapping guided radiofrequency ablation.

Electrophysiological breakthroughs from the left atrium to the pulmonary veins.

BACKGROUND: The extent of ostial ablation necessary to electrically disconnect the pulmonary vein (PV) myocardial extensions that initiate atrial fibrillation from the left atrium has not been determined. METHODS AND RESULTS: Seventy patients underwent PV mapping with a circumferential 10-electrode catheter during sinus rhythm or left atrial pacing. After assessment of perimetric distribution and activation sequence of PV potentials, ostial ablation was performed at segments showing earliest activation, with the end point of PV disconnection. A total of 162 PVs (excluding right inferior PVs) were ablated. PV potentials were present at 60% to 88% of their perimeter, but PV muscle activation was always sequential from a segment with earliest activation (breakthrough). Radiofrequency (RF) application at this breakthrough eliminated all PV potentials in 34 PVs, whereas a secondary breakthrough required RF applications at separate segments in 77; in others, >2 segments were ablated. A median of 5, 6, and 4 bipoles from the circular catheter were targeted in the right superior, left superior, and inferior PVs, respectively, to achieve PV disconnection. Early recurrence of arrhythmia was observed in 31 patients as a result of new venous or atrial foci or recovery of previously targeted PVs, most related to a single recovered breakthrough that was reablated with local RF application. CONCLUSIONS: Although PV muscle covers a large extent of the PV perimeter, there are specific breakthroughs from the left atrium that allow ostial PV disconnection by use of partial perimetric ablation.

Efficacy and safety of an irrigated-tip catheter for the ablation of accessory pathways resistant to conventional radiofrequency ablation.

BACKGROUND: Radiofrequency catheter ablation of accessory pathways (APs) is very effective in all but a minority of patients. We examined the usefulness and safety of irrigated-tip catheters in treating patients with APs resistant to conventional catheter ablation. METHODS AND RESULTS: Among 314 APs in 301 consecutive patients, conventional ablation failed to eliminate AP conduction in 18 APs in 18 patients (5.7%), 6 of which were located in the left free wall, 5 in the middle/posterior-septal space, and 7 inside the coronary sinus (CS) or its tributaries. Irrigated-tip catheter ablation was subsequently performed with temperature control mode (target temperature, 50 degrees C), a moderate saline flow rate (17 mL/min), and a power limit of 50 W (outside CS) or 20 to 30 W (inside CS) at previously resistant sites. Seventeen of the 18 resistant APs (94%) were successfully ablated with a median of 3 applications using irrigated-tip catheters. A significant increase in power delivery was achieved (20.3+/-11.5 versus 36.5+/-8.2 W; P:<0.01) with irrigated-tip catheters, irrespective of the AP location, particularly inside the CS or its tributaries. No serious complications occurred. CONCLUSIONS: Irrigated-tip catheter ablation is safe and effective in eliminating AP conduction resistant to conventional catheters, irrespective of the location.

Tracking dynamic conduction recovery across the cavotricuspid isthmus.

OBJECTIVES: We sought to assess the dynamic temporal course of conduction recovery during and after radiofrequency (RF) catheter ablation of the cavotricuspid isthmus. BACKGROUND: Although cavotricuspid isthmus block is accepted as the best end point of ablation for typical flutter, conduction recovery is thought to underlie many eventual recurrences. Its time course and frequency have not been determined. METHODS: In a prospective group of 30 patients (26 men and 4 women, age 64 +/- 12 years) undergoing ablation of typical flutter in the cavotricuspid isthmus, the morphology of the P wave during pacing from the low lateral right atrium after achievement of complete isthmus block was identified as a reference. Regression of this morphologic P wave change was confirmed to be associated with intracardiac evidence of the recovery of cavotricuspid isthmus conduction and was observed throughout the procedure both during ablation in sinus rhythm (n = 15, group B) and just after flutter termination (n = 15, group A). RESULTS: Stable complete isthmus block was achieved in all patients; 29 had a terminal positivity of the paced P wave. Flutter termination resulted in stable block and terminal P wave positivity in three patients, transient terminal P wave positivity and transient block despite continuing RF at the same site in five patients and no block in the remaining seven patients. Conduction recovery identified by recovery of P wave changes was nearly as common (48%) during ablation in sinus rhythm. Multiple recoveries were noted in some patients, and 72% of all recoveries occurred within 1 min. Conduction recovery was only rarely associated with coagulum, impedance elevation or pops. CONCLUSIONS: Conduction recovery in the cavotricuspid isthmus is common during and after ablation and can be accurately, dynamically and continuously observed by monitoring the recovery of the low lateral right atrial paced P wave change.

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.

Predictive value of electrophysiologic studies during treatment of ventricular tachycardia with the beta-blocking agent nadolol. The Working Group on Arrhythmias of the French Society of Cardiology.

Sixty patients with recurrent inducible sustained ventricular tachycardia were prospectively treated with nadolol (40 or 80 mg/day). Old myocardial infarction was present in 43 patients and dilated cardiomyopathy in 12. In group I (n = 36), nadolol was given alone, whereas in group II (n = 24), previously ineffective treatment with amiodarone was continued in combination with nadolol. Left ventricular ejection fraction was higher in patients in group I (0.40 +/- 0.12) than in group II (0.30 +/- 0.10, p less than 0.01) patients. Electrophysiologic study was repeated after short-term treatment with nadolol, which was continued regardless of the results of this test, according to the scheme of the parallel approach. Recurrence of spontaneous tachycardia or sudden death occurred in 21 patients after 10 +/- 9.2 months; sustained tachycardia was inducible in 19 on nadolol therapy. The remaining 39 patients (of whom 21 had inducible tachycardia while taking the drug) have had no recurrence of tachycardia after 27.8 +/- 9.3 months of follow-up study. Sensitivity, specificity and predictive value of a positive and negative test were 90.5%, 46%, 47.5% and 90%, respectively. The results differ between group I and group II patients, the latter having a high percent of false positive responses. This difference is even more obvious with respect to left ventricular ejection fraction: the predictive value of a positive test was 86% when ejection fraction was greater than 0.40 and 39% when it was less than 0.40.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial cavotricuspid isthmus block before ablation in patients with typical atrial flutter.

OBJECTIVES: The purpose of this study was to prospectively evaluate preexisting partial isthmus block in the context of an electrophysiologically directed linear ablation strategy for typical atrial flutter (AF). BACKGROUND: Double potentials (DPs) separated by an isoelectric interval have been recognized as markers of local block. However, the presence and significance of DPs in the cavotricuspid isthmus during AF before ablation have not been evaluated. METHODS: Thirty consecutive patients with AF (counterclockwise: 24, clockwise: 6) were studied during AF. Sequential withdrawal mapping was performed in the cavotricuspid isthmus from the tricuspid valve (TV) to the inferior vena cava (IVC) edge with electrograms coinciding with the center of the surface electrocardiographic plateau during counterclockwise AF or with the initial downslope of the positive flutter wave during clockwise AF. Atrial electrograms along this line were categorized as double, single or fractionated potentials (SPs or FPs). After demarcation of the zone of contiguous DPs, radiofrequency (RF) catheter ablation was performed during AF only at sites with SPs or FPs (other than DPs) on the mapped line. If isthmus conduction still persisted after AF termination, additional RF applications were delivered using the same electrophysiologic strategy of avoiding DPs with an isoelectric interval during low lateral right atrial pacing for filling in the gap of residual conduction. RESULTS: Before ablation, no DPs were recorded in the isthmus in 19 patients (63%); DPs were recorded only at the IVC edge in five patients, and only at the TV edge in one patient. A contiguous line of DPs extending through more than half the isthmus to the IVC edge was documented in five patients (17%: group DP). In group DP, AF was terminated with 1.4+/-0.5 applications (vs. 5.8+/-3.5 in the remaining patients: p < 0.01). Complete isthmus block was achieved with a total of 3.4+/-0.5 applications (vs. 12+/-6 in the remaining patients: p < 0.01). CONCLUSIONS: Seventeen percent of patients undergoing ablation of AF have preexisting partial isthmus block indicated by a large contiguous zone of DPs separated by an isoelectric interval. Electrophysiologically directed linear ablation avoiding confluent DPs can prevent unnecessary applications for effective cure of AF.

Morphological characteristics of P waves during selective pulmonary vein pacing.

OBJECTIVES: We sought to assess the value of 12-lead electrocardiogram (ECG) P-wave morphology to recognize the paced pulmonary vein (PV). BACKGROUND: Prediction of arrhythmogenic PVs producing ectopy or initiating atrial fibrillation (AF) using 12-lead ECG may facilitate curative ablation. METHODS: In 30 patients P-wave configurations were studied during sinus rhythm and during pacing at six sites from the four PVs: top and bottom of each superior PV and both inferior PVs. The P-wave amplitude, duration and morphology were assessed, and predictive accuracies were calculated for the most significant parameters. An algorithm predicting the paced PV was developed and prospectively evaluated in a different population of 20 patients. RESULTS; Three criteria were used to distinguish right from left PV: 1) a positive P-wave in lead aVL and the amplitude of P-wave in lead I > or =50 microV indicated right PV origin (specificity 100% and 97%, respectively); 2) a notched P-wave in lead II was a predictor of left PV origin (specificity 95%); and 3) the amplitude ratio of lead III/II and the duration of positivity in lead V(1) were also helpful in distinguishing left versus right PV origin. In addition, superior PVs could be distinguished from inferior according to the amplitude in lead II (> or =100 microV). In prospective evaluation, an algorithm based on the above four criteria identified 93% of left versus right PV and totally 79% of the specific PVs paced. CONCLUSIONS: Pacing from the different PVs produced a P-wave with distinctive characteristics that could be used as criteria in an algorithm to identify the PV of origin with an accuracy of 79%.

[Outcome of 30 congenital atrio-ventricular blocks]. / Devenir à long terme de 30 blocs auriculo-ventriculaires complets congénitaux isolés.

Congenital isolated atrio-ventricular block (CAVB) is a rare pathology, and its management is still rather poorly described through international literature. Within the service of pediatric cardiology leaded by Pr Choussat and Dr Jimenez (Cardiologic Hospital Haut-Lévêque of Bordeaux), we collected from 1980 to 2003, 30 isolated congenital CAVB, constituting the purpose of this retrospective study. Average follow-up is 14 +/- 8.8 years. None death occurred. CAVB are discovered at an average age of 4.8 years old; 6 cases were diagnosed in utero, half of them were associated with maternal lupus. Twenty patients on 30 were fitted with stimulator at an average age of 8.7 +/- 6.9 years old, due to symptoms or bradycardy. Epicardic fitting in VVI mode represents 65% of first approaches, it is followed by endocavitary way for 81% of cases. Cardiac stimulation does not prevent from dilated cardiomyopathy. Among 30 patients 10 were not fitted with stimulator, half of them presents chronotrop insufficiency during effort. As a conclusion, our patients show a good long-term vital prognosis; although CAVB discovered in utero lead to worse prognosis for children.

[Biochemical detection of Conn's adenoma: definition of criteria and reference values]. / Dépistage biologique des adénomes de Conn: definition des critères et des seuils.

Primary hyperaldosteronism is a diagnosis which should be considered in refractory hypertension even in the absence of any hypokalaemia. Its detection relies above all on the levels of renin and aldosterone. The aldosterone/renin ratio has been proposed as the most sensitive criterium. The reference values used for the diagnosis of primary hyperaldosteronism are very variable in the literature, depending not only on the method used but also on the criteria used for their determination. In this study we evaluated the defined reference values prospectively by studying a population of patients with a Conn's adenoma treated surgically. The study included an initial retrospective period which allowed identification of 29 cases of Conn's adenoma treated surgically, and a 9 month prospective period during which 212 reports were collected. During this prospective period a further 9 cases of Conn's adenoma were detected, which were successfully treated with surgery. Analysis to discriminate the 38 Conn's adenomata from the rest showed that 3 parameters contributed significantly and independently to the diagnosis: supine plasma renin activity (ARPc), supine aldosteronaemia and the erect aldosterone/renin ratio, allowing correct classification in 88% of the cases. The reference ranges of these 3 parameters were calculated in order to give a sensitivity of 100% and the best possible specificity, therefore allowing a combined criterium involving all 3 parameters to be defined: ARPc < 0.45 ng/ml/h, supine aldosteronaemia >417 pmol/l, and erect aldosterone/renin >1180.

[Mapping and ablation of malignant ventricular arrhythmias]. / Cartographie et ablation des arythmies ventriculaires malignes.

Endocavitary investigations showed that the ventricular extrasystoles originated in the common ventricular myocardium (pulmonary infundibulum) in only 9 cases whereas the majority arose from the Parkinje system either on the anterior wall of the right ventricle or in septal region of the left ventricle. The extrasystoles arising from the Parkinje system and pulmonary infundibulum differed in their duration and polymorphism (128 +/- 18 ms vs 145 +/- 13 ms, p = 0.05; 3.3 +/- 2.7 morphologies vs 1.1 +/- 0.4, p < 0.001, respectively). During the extrasystoles, the local Pukinje potential preceded the ventricular activation by variable intervals, some of which were very long, up to 150 ms. Seven applications of radiofrequency were delivered on average per patient on the most distal part of the Purkinje system leading to ablation of the specific activation. The clinical results were spectacular: 88% of patients had no further episodes of ventricular fibrillation as demonstrated by analysis of the defibrillator with an average follow-up period of more than 34 months.

[Asynchronism and right ventricular pacing]. / Asynchronisme et stimulation ventriculaire droite. Démonstration de l'effet délétère d'une stimulation apicale dans une population d'adultes appareillés pour BAV congénital.

UNLABELLED: In patients with congenital heart block (CHB), dual-chamber pacing restores physiological heart rate and atrio-ventricular synchronization. However, patients with narrow QRS junctional escape rhythm may be deleteriously affected by long-term, permanent, apical ventricular pacing. We assessed the impact of apical ventricular pacing on echocardiographic ventricular dyssynchrony and hemodynamic parameters. METHODS: Fourteen CHB adults (23 +/- years, 58% male), with a DDD transvenous pacemaker and a junctional escape rhythm (QRS<120 ms) before implantation, were studied. Echocardiography coupled with tissue Doppler imaging (TDI) and Strain rate was performed in spontaneous rhythm (VVI mode 30/mn) and during atrio-synchronized ventricular pacing. RESULTS: The heart rate (43 +/- 09 vs 68 +/- 07: p<0.01), cardiac output (2.9 +/- 0.7 vs 3.7 +/- 0.6 L/min) and left ventricular filling time (325 +/- 38 vs 412 +/- 51 ms; p<0.01) were significantly less in the escape spontaneous rhythm compared with atrio-ventricular synchronized apical pacing. However, interventricular dyssynchrony (28 +/- 12 vs 59 +/- 25 ms, p<0.05), intra-left ventricular dyssynchrony (36 +/- 11 vs 57 +/- 29 ms; p<0.05), extent of left ventricular myocardium displaying delayed longitudinal contraction (26 +/- 10 vs 39 +/- 17%: p<0.05) were significantly less in the escape rhythm compared with paced rhythm. CONCLUSION: Once implanted with a DDD pacemaker, CHB patients present with increased cardiac output secondary to the restoration of physiological heart rate and improved diastolic function. However, the apical site is not optimal, as it creates detrimental ventricular dyssynchrony in patients with previous nearly physiological ventricular activation. Alternative pacing sites should be investigated.

[Characterization of premature ventricular contraction initiating ventricular fibrillation]. / Caractéristiques morphologiques des extrasystoles ventriculaires initiatrices des fibrillations ventriculaires.

UNLABELLED: The aim of this study is to characterize the electrocardiographic features of premature ventricular contractions (PVC) from different anatomical region that trigger ventricular fibrillation (VF). METHODS AND RESULTS: 36 consecutives patients (20 males, 42+/-14 yrs) undergoing VF ablation from 7 centres were studied (22 with idiopathic VF, 4 associated with a long QT syndrome, 3 with Brugada syndrome, 4 with ischaemic cardiomyopathy and 3 associated with other substrate). Mapping of these PVC showed 2 different origins, which were then confirmed by ablation: right ventricular outflow tract (RVOT) (22%) and peripheral Purkinje network (81%). One patient had PVC from both origins (Brugada). RVOT PVC were frequent but had triggered only 5+/-5 episodes of VF for 26+/-33 months. Purkinje PVC were more likely to be present during electrical storm with 18+/-28 episodes of VF for 33+/-45 months. Right Purkinje PVC have a left bundle branch block with superior axis morphology whereas left Purkinje ones have a right bundle branch block. The axis of activation showed variation from inferior to superior depending on the area of origin from the Purkinje network and the exit site to the myocardium. However Purkinje PVC were characterized by short QRS duration (126+/-18 vs 145+/-13ms for RVOT PVC; p=0.05). In addition the coupling interval was significantly shorter compared to RVOT PVC (292+/-45 vs 358+/-37ms respectively; p=0.005). CONCLUSION: PVC initiating VF demonstrate specific electrocardiographic features that facilitate determination of their origin. Ablation of these typical PVC is feasible in order to reduce ICD shock.

Echocardiographic advances in atrial fibrillation and supraventricular arrhythmias.

Advances in echocardiography have paved the way for the development of intracardiac catheters with ultrasound transducers mounted on its tip. With this technology it has become possible for the interventional electrophysiologist to perform continuous echocardiographic examination during a procedure without the need for general anaesthesia or additional staff. Intracardiac echocardiography (ICE) allows the monitoring of catheter movement in real-time, assessment of catheter-tissue contact and potentially prevents and recognizes complications like thrombus formation and pericardial effusion. In addition recent technologies allow acquiring the full spectrum of Doppler-imaging permitting evaluation of haemodynamic data during the procedure. All these advances have made ICE an ideal tool for the interventional electrophysiologist, serving as a diagnostic and imaging tool during invasive electrophysiological procedures. This review will summarize currently available technology of ICE and its indications and applications in electrophysiological procedures.