Impact of real-time contact force and impedance measurement in pulmonary vein isolation procedures for treatment of atrial fibrillation.

BACKGROUND: Pulmonary vein isolation (PVI) is an established procedure to treat atrial fibrillation (AF). New techniques are necessary to improve procedural parameters like shortening of procedure duration. Real-time contact force (CF) catheters are new tools aiming to improve PVI by optimizing electrode-tissue contact and generating more effective lesions. Objective of this study was to investigate the influence on procedural parameters and clinical outcome by using a CF catheter for PVI. METHODS: PVI was performed on 67 consecutive patients using a CF catheter (n = 32) or a standard ablation catheter (SAC, n = 35). Study endpoints included number of energy applications, impedance drop, fluoroscopy time, and left atrial (LA) procedure time and freedom from AF after 6 and 12 months. RESULTS: Procedural endpoint was reached in all patients with a similar clinical outcome (freedom from AF) in both groups 6 months (62.9 vs. 62.5%) and 12 months post PVI (59.4 vs. 62.9% in CF vs. SAC group, respectively). However, CF-guided ablation resulted in a greater fall of impedance (6.58 ± 0.33 vs. 9.09 ± 0.53 Ω, *** p < 0.001), lower number of energy applications (44.20 ± 3.67 vs. 34.06 ± 3.11, * p < 0.05), reduction of LA procedure time (95.52 ± 7.35 vs. 78.08 ± 7.23* min) and a significant reduction of fluoroscopy time (51.4 ± 3.3 vs. 33.0 ± 2.7*** min). In addition, a detailed analysis showed a significant correlation between quantitative impedance drop and amount of CF applied, suggesting more efficient lesion creation by CF-guided ablation. CONCLUSION: Use of CF catheters in PVI has a beneficial effect on procedural parameters, probably by improving efficacy of transmural lesion formation.

Recording of low-amplitude diastolic electrograms through the coronary veins: a guide for epicardial ventricular tachycardia ablation.

AIMS: The purpose of the study was to evaluate the role of coronary venous mapping to identify epicardial ventricular tachycardia (VT) in patients with structural heart disease. METHODS AND RESULTS: Epicardial mapping of the electrophysiological substrate through the coronary vein branches using a 2.2F, 16-pole microelectrode catheter was performed in 33 consecutive patients undergoing VT ablation. Twenty-six patients had a history of myocardial infarction and seven had a non-ischaemic cardiomyopathy. Endocardial ablation was successful in 19 of the 33 patients (58%). Low-amplitude fractionated diastolic electrograms with an electrogram-QRS interval amounting to 30-70% of the VT cycle length were recorded during the VT in the coronary vein branches in eight patients (24%). Endocardial ablation failed in seven of the eight patients with diastolic electrograms in the coronary veins, suggesting an epicardial involvement of the VT re-entry circuit. Among the patients with a suspected epicardial VT origin, four patients underwent epicardial ablation using a pericardial access after unsuccessful endocardial ablation which eliminated mappable VTs in all. CONCLUSION: Recording of low-amplitude fractionated diastolic electrograms through the coronary veins facilitates the identification of VTs with an epicardial origin requiring mapping and ablation through a pericardial access.

Different forms of ventricular tachycardia involving the left anterior fascicle in nonischemic cardiomyopathy: critical sites of the reentrant circuit in low-voltage areas.

INTRODUCTION: The purpose of this study was to examine the reentrant circuit of ventricular tachycardias (VTs) involving the left anterior fascicle (LAF) in nonischemic cardiomyopathy. METHODS AND RESULTS: Six patients with nonischemic cardiomyopathy presented with VTs involving the LAF. Potentials in the diastolic or presystolic phase of the VT were identified close to the LAF in 3 patients and in the mid or inferior left ventricular (LV) septum in 3 patients. Superimposed on a CARTO or NavX 3-dimensional voltage map, the diastolic and presystolic potentials were recorded within or at the border of a low-voltage zone in the LV septum in all cases. In 2 patients, both left bundle fascicles participated in the reentrant circuit including a possible interfascicular VT in one case. Ablation targeting the diastolic or presystolic potentials near the LAF or in the midinferior LV septum eliminated the VTs in all patients with the occurrence of a left posterior fascicular block and the delayed occurrence of a complete atrioventricular block in each one patient. During the follow-up of 23 +/- 20 months after ablation, 4 patients were free of ventricular tachyarrhythmias. Due to detoriation of heart failure, one patient died after 12 months and one patient underwent heart transplantation after 40 months. CONCLUSIONS: Slow conduction in diseased myocardium close to the LAF or in the middle and inferior aspects of the LV septum may represent the diastolic pathway of VT involving the LAF.

Analysis during sinus rhythm and ventricular pacing of reentry circuit isthmus sites in right ventricular cardiomyopathy.

BACKGROUND: The entrainment mapping algorithm is used for ablation of ventricular tachycardia (VT) in right ventricular (RV) cardiomyopathy, but ablation at endocardial isthmus sites has only a moderate success rate. This study was performed to identify additional local electrogram characteristics associated with successful ablation. PATIENTS AND METHODS: Using entrainment mapping, 45 reentry circuit isthmus sites were detected in 11 patients with RV cardiomyopathy presenting with 13 monomorphic VTs. Local bipolar electrograms were retrospectively analyzed at reentry circuit isthmus sites during VT, sinus rhythm, and programmed stimulation from the right ventricular apex (RVA), and compared between successful and unsuccessful ablation sites. RESULTS: Ablation was successful at 10 reentry circuit isthmus sites and unsuccessful at 35 isthmus sites. During VT, a longer endocardial activation time relative to QRS onset, an increased electrogram-QRS interval as a percentage of VT cycle length, and a longer electrogram duration were found at successful in comparison to unsuccessful ablation sites. The presence of isolated diastolic potentials during sinus rhythm at reentry circuit isthmus sites, consistent with slow conduction or unidirectional conduction block, was associated with successful catheter ablation. Prolongation of the duration of the local multipotential electrogram by >100 ms during programmed RVA pacing at reentry circuit exit sites, indicating functional conduction disorder was also a marker of successful ablation. CONCLUSIONS: The demonstration of multipotential electrogram characteristics indicating fixed or functional conduction block may increase the likelihood of successful VT ablation at exit and central isthmus sites of reentry circuits in RV cardiomyopathy.

Ventricular tachycardia with participation of the left bundle-Purkinje system in patients with structural heart disease: identification of slow conduction during sinus rhythm.

INTRODUCTION: Idiopathic left ventricular tachycardia (VT) originating from the left posterior fascicle can be eliminated by ablation at sites with abnormal diastolic potentials (DPs) during sinus rhythm. We investigated whether such DPs can also be recorded in patients with structural heart disease and VT involving the left bundle-Purkinje system. METHODS AND RESULTS: Eight patients (mean age 67 +/- 11 years) with nonischemic cardiomyopathy (n = 5) or prior myocardial infarction (n = 3) presented with VT involving the left bundle-Purkinje system (cycle length 376 +/- 45 ms). Three types of VT were observed: macroreentrant VT with participation of both left bundle fascicles in three patients, fascicular VT involving the left posterior fascicle in two patients, and scar-related VT with Purkinje fibers as part of the reentrant circuit in three patients. In all patients, abnormal isolated DPs of low amplitude with a QRS-earliest DP interval of 374 +/- 86 ms were found during sinus rhythm in the mid- or inferior left ventricular septum in areas with Purkinje potentials. The abnormal DPs during sinus rhythm coincided or were in proximity to DPs during the VT in six patients. VT ablation targeting the sites with the earliest abnormal DPs during sinus eliminated the VT in 7 of 8 patients with freedom from VT recurrence in six patients during the follow-up of 11 +/- 5 months. CONCLUSIONS: Isolated DPs during sinus rhythm were found in proximity to the posterior Purkinje network in patients with VT involving the left bundle-Purkinje system associated with heart disease and can be used to guide successful catheter ablation.

A NavX-guided ablation of a nodo-fascicular fibre.

The NavX system was used to guide mapping and successful ablation of a reciprocating antidromic tachycardia involving anterograde conduction over a nodo-fascicular fibre and retrograde conduction over the His bundle and AV node. This novel mapping system allowed visualization of the lower insertion site of the nodo-fascicular accessory pathway approximately 1.5-2 cm away from the tricuspid annulus in a three-dimensional reconstruction of the right atrium and right ventricle.

Reinitiation of ventricular macroreentry within the His-Purkinje system by back-up ventricular pacing - a mechanism of ventricular tachycardia storm.

BACKGROUND: We describe immediate reinitiation of macroreentry ventricular tachycardia (VT) involving the His-Purkinje system by ventricular pacing from the electrode of an implantable cardioverter defibrillator (ICD) as a mechanism of VT storm refractory to ICD therapy. METHODS AND RESULTS: Repetitive reinitiation of bundle branch reentry tachycardia (BBRT), interfascicular tachycardia, or both VTs by ventricular pacing was identified in four ICD patients presenting with VT storm or incessant VT. All patients had a pre-existing prolonged HV interval (75 +/- 9 ms) and left bundle branch block (LBBB) or bifascicular block during sinus rhythm. The VTs included BBRT with LBBB in three patients and interfascicular tachycardia with right bundle branch block (RBBB) and left anterior or left posterior fascicular block in two patients. The paced beats from the ICD electrode exhibited a LBBB pattern of depolarization in two patients and a RBBB contour in V1 and V2 with left axis deviation in two patients. The QRS complex during pacing from the ICD electrode closely resembled that of the recurrent VT in all four patients suggesting that the pacing site of the ICD electrode was in proximity to the myocardial exit site of the bundle fascicle used for antegrade conduction during the reinitiated VT. Ventricular pacing from the ICD electrode after termination of the VT apparently encountered the retrograde refractoriness of this bundle fascicle and allowed immediate re-propagation of the wavefront orthodromically along the VT circuit. BBRT was eliminated by ablation of the right bundle branch. Successful ablation of the interfascicular tachycardias was achieved by targeting (1) an abnormal potential of the distal left posterior Purkinje network or (2) a diastolic potential during VT in the midinferior left ventricular (LV) septum. CONCLUSIONS: Repetitive reinitiation of BBRT and interfascicular tachycardia by ventricular pacing from the ICD electrode should be considered as a mechanism of VT storm refractory to ICD therapy in patients with a pre-existing conduction delay within the His-Purkinje system.

Electroanatomic mapping of endocardial right ventricular activation as a guide for catheter ablation in patients with arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia is a structural heart disease characterized by fibrofatty degeneration of right ventricular myocardium and arrhythmias of right ventricular origin. The aim of this study was to characterize endocardial right ventricular activation by electroanatomic mapping as a guide for catheter ablation in patients with arrhythmogenic right ventricular dysplasia. Electroanatomic mapping and entrainment procedures were performed in 5 patients with arrhythmogenic right ventricular dysplasia. Endocardial mapping during ventricular tachycardia demonstrated a focal activation pattern with radial spreading of activation from a site of earliest ventricular activation in all directions. Right ventricular activation time (127 +/- 34 ms) was markedly shorter than tachycardia cycle length (415 +/- 92 ms). The site of earliest ventricular activation was found in an aneurysmal outflow tract (n = 2), at the border of aneurysms near the tricuspid annulus (n = 2), and at the apex of the right ventricle (n = 1). Entrainment mapping criteria of these areas of earliest endocardial activity were consistent with exit sites of a reentrant circuit in an area of abnormal myocardium. Fractionated potentials were found 61 +/- 29 ms before the onset of the QRS complex at these sites. Catheter ablation rendered the "clinical" ventricular tachycardia noninducible in four patients but "nonclinical" faster ventricular tachycardias were inducible in three patients. During the follow-up of 7 +/- 3 months after ablation, the frequency of therapies in 4 patients with an implantable cardioverter defibrillator decreased from 49 +/- 61 episodes per month before ablation, to 0.3 +/- 0.5 episodes per month after ablation (P < 0.05). Electroanatomic mapping during ventricular tachycardia facilitates localization of exit sites in relation to aneurysms in diseased right ventricle and may guide catheter ablation in patients with arrhythmogenic right ventricular dysplasia.

Suppression of concealed pulmonary vein bigeminy by atrial pacing in a patient with paroxysmal atrial fibrillation.

Concealed pulmonary vein bigeminy, as a pair of a pulmonary vein spike potential within a fragmented far-field atrial electrogram and a premature ectopic pulmonary vein spike potential with exit block, was continuously recorded in a patient with paroxysmal AF. Atrial pacing suppressed the breakthrough from the left atrium to the pulmonary vein, thus preventing the conducted and the premature ectopic pulmonary vein potentials. Atrial pacing induced conduction block between the left atrium and the arrhythmogenic pulmonary vein might be a possible explanation for the prevention of paroxysmal AF by atrial pacing.

Pulmonary vein bigeminy: electrophysiological characteristics and results of catheter ablation.

UNLABELLED: Pulmonary vein bigeminy is the pair of a second, late and ectopic pulmonary vein potential following atrial far-field activation and a first passive pulmonary vein potential during sinus rhythm. The aim of this study was to determine the electrophysiological characteristics of pulmonary vein bigeminy and to evaluate its relevance as a trigger for paroxysmal atrial fibrillation. METHODS AND RESULTS: Pulmonary vein bigeminy was recorded in 8 of 45 patients (18%) who underwent mapping of pulmonary veins for ablation of focal atrial fibrillation. The premature ectopic pulmonary vein potentials were conducted to the atria in 5 patients and were not conducted (concealed bigeminy) in 3 patients. The coupling interval of the ectopic pulmonary vein potential to the preceding atrial signal during sinus rhythm was significantly longer in patients with conducted bigeminy (375 +/- 25 ms) than with concealed bigeminy (230 +/- 17 ms). The pulmonary vein bigeminy was driven by coronary sinus pacing with the pacing cycle length at lower stimulation rates and was suppressed by overdrive pacing. Coronary sinus pacing led to a separation of the first pulmonary vein potential from the atrial signal but the interval between the atrial signal and the second pulmonary vein potential remained unchanged. Focal ablation at the site of earliest ectopic pulmonary vein activity in 5 patients induced rapid repetitive firing before elimination of the pulmonary vein bigeminy. Ostial disconnection of the arrhythmogenic pulmonary vein in 3 patients was associated with elimination of the pulmonary vein bigeminy. During the follow-up of 9 +/- 5 months after ablation of the pulmonary vein bigeminy, 5 of the 8 patients (63%) were free of atrial fibrillation without antiarrhythmic medication. CONCLUSIONS: The response of pulmonary vein bigeminy to atrial pacing and ostial ablation suggests that pulmonary vein bigeminy depends on an intact electrophysiological breakthrough between the left atrium and the pulmonary vein. Ablation targeting the pulmonary vein bigeminy is a possible limited approach for this subgroup of patients with paroxysmal atrial fibrillation.