Clinical Approach to Symptomatic and Asymptomatic Patients with Ventricular Pre-excitation.

Despite extensive knowledge of the physiopathology of ventricular pre-excitation, management of asymptomatic patients with this condition remains controversial.

Comparison of Electrophysiologic Profiles in Pediatric Patients with Incidentally Identified Pre-Excitation Compared with Wolff-Parkinson-White Syndrome.

The rising utilization of screening electrocardiograms has resulted in increased incidental identification of ventricular pre-excitation in pediatric patients. We compared accessory pathways of incidentally identified pre-excitation to Wolff-Parkinson-White Syndrome (WPW) with the aim to identify factors important in preprocedural counseling and planning. This single-center, retrospective study of patients ≤18 years without congenital heart disease identified 227 patients diagnosed with pre-excitation and referred for invasive electrophysiology study between 2008 and 2017. WPW Syndrome was diagnosed in 178 patients, while 49 patients had incidental identification of pre-excitation. Anterograde conduction of incidentally identified accessory pathways was not clinically different between the two cohorts at baseline or upon isoproterenol infusion. However, the proportion of accessory pathways meeting high-risk criteria was significantly lower than in patients diagnosed with WPW, 12% versus 28% (p < 0.05). Retrograde conduction at baseline of incidentally diagnosed accessory pathways was slower with a median block cycle length 365 milliseconds (IQR 260 to 450) versus 290 milliseconds (IQR 260 to 330, p < 0.01). In the incidentally identified cohort, right-sided, paraHisian, and fascicular pathways were more common with fewer attempted ablations (71% vs 94%, p < 0.001) and lower success rate (91% vs 97%, p < 0.001). A binomial logistic regression analysis further indicated patients incidentally identified with pre-excitation were associated with having lower rates of inducible supraventricular tachycardia, atrial fibrillation, and ablations performed, in addition, to having right-sided pathways. In conclusion, as patients with incidentally identified pre-excitation present more frequently for consideration of invasive electrophysiology study, these results impact procedural approaches, technical considerations, patient counseling, and outcome expectations.

Electroanatomic mapping-guided pediatric catheter ablation with limited/zero fluoroscopy.

OBJECTIVE: The use of fluoroscopy in pediatric catheter ablation has decreased because of mapping systems. In this study, we present the efficiency and reliability of the electroanatomic mapping system in nonfluoroscopic pediatric catheter ablation. METHODS: The medical records of patients aged <18 years who underwent ablation between November 2016 and April 2018 were evaluated. Fluoroscopy was not used in cases involving ablation of right sided-arrhythmia foci. Fluoroscopy was used only for trans-septal puncture or retroaortic approach/coronary angiography. RESULTS: A total of 76 patients underwent catheter ablation for 78 supraventricular and ventricular tachyarrhythmia substrates under the guidance of EnSite Velocity system. Fluoroscopy was used in only 14 (18.4%) of these substrates. The mean fluoroscopy duration in these 14 procedures was 5.4±3.15 min. No complications were noted, except a temporary right bundle branch block in one patient and pericardial effusion in another following cryoablation. The acute success rate in achieving complete elimination of arrhythmia substrates was 97.4% (76/78). The recurrence rate was 5.1% (4/78) at follow-up. CONCLUSION: Fluoroscopy can be completely eliminated in most pediatric catheter ablation procedures with the use of mapping systems by achieving high acute success rates and acceptable low complication rates.

Invasive electrophysiological evaluation and ablation in patients with asymptomatic ventricular pre-excitation persistent at exercise stress test.

AIMS: In patients with asymptomatic ventricular pre-excitation (VPE) persistent at exercise stress test, this study evaluates the proportion of cases with adverse conduction properties of the atrioventricular accessory pathway (AP) at invasive electrophysiological study and the long-term follow-up after they received treatment according to pre-determined criteria. METHODS AND RESULTS: Over 10 years, asymptomatic patients with VPE persistent at exercise stress test referred for invasive electrophysiological evaluation including isoproterenol (IPN) infusion were included. Ablation was planned if they had at least one of the following criteria: (i) shortest pre-excited R-R interval (SPERRI) ≤250 ms and/or (ii) inducible atrioventricular re-entrant tachycardia (AVRT). Cryoablation was electively used in para-hisian and mid-septal APs. Patients non-eligible for ablation received no therapy. Sixty-three patients (45 males; mean age 26 ± 14 years) underwent electrophysiological evaluation: 7 had fasciculo-ventricular fibres and were excluded, whereas 56 had 58 APs. Thirty-one patients (55%) were eligible and underwent successful ablation: 87% had at least the SPERRI ≤ 250 ms and 61% had at least inducible AVRT. In 15 cases (48%) the ablation criteria were met only during IPN infusion. During follow-up (73 ± 33 months), one patient was successfully retreated for resumption of VPE in the ablation group, whereas no event was observed in the group of patients who received no treatment. CONCLUSION: In this subset of patients with asymptomatic VPE, invasive electrophysiological evaluation shows fast antegrade conduction over the AP and/or inducible AVRT in about half of the cases. Patients who received no therapy because of a benign electrophysiological profile had an event-free follow-up.

Left ventricular dyssynchrony in pre-excitation syndrome: effect of accessory pathway location and reversibility after ablation therapy.

We sought to evaluate the effects and reversibility of different locations of accessory pathways (AP) on left ventricular dyssynchrony (LVdys). The acute and chronic effects of AP were evaluated in a canine model (n = 11) and in patients with pre-excitation syndrome (n = 25). Pre-excitation was simulated in the canine model by applying VDD-type epicardial ventricular pacing near the atrioventricular (AV) groove with 50-ms AV interval after median thoracotomy, at five different sites in each animal. For the simulation of pre-excitation through the septal accessory pathway, right basal septal pacing was performed using a transvenous lead. Left ventricular dyssynchrony was measured by a two-dimensional speckle-tracking technique: before and during pacing in the canine model, and before and within 24 h after the ablation in patients with Wolff-Parkinson-White (WPW) syndrome. In the canine model, the most prominent intraventricular LVdys was observed in left lateral pre-excitation (P < 0.001). In patients with pre-excitation syndrome, LVdys was greatest in patients with left free wall accessory pathways before the ablation (P = 0.013). After catheter ablation, such a difference diminished (P = 0.619). The degree of LVdys was different according to the site of AP in both the acute model and chronic patients, and the most significant LVdys associated with pre-excitation was observed in left lateral AP. Left ventricular dyssynchrony was reversible in patients with WPW syndrome. Left ventricular dyssynchrony observed in patients with pre-excitation syndrome might be a different entity from that observed in patients with heart failure.

[Prograde conduction of the pathway in pre-excitation syndrome may shorten PJ interval].

OBJECTIVE: To investigate whether the PJ interval in the patients with pre-excitation syndrome can be shortened by pathway conduction, and to explore the clinical implications of the prolonged PJ interval. METHODS: 143 patients with single pathway, who experienced successful radiofrequency (RF) ablation, were divided into two groups: Group A (n = 132) with normal atrioventricular and ventricular conduction (sub-divided into 10 subsets further according to the location of the pathway) and Group B (n = 11) with first degree atrioventricular block or with bundle branch block. The ECG images with and without pathway conduction were analyzed. RESULTS: (1) The PJ interval in the patients with right posterior pathway or with right septal pathway was shortened significantly after the RF [(226 +/- 18) ms vs (236 +/- 19) ms and (221 +/- 18) ms vs (238 +/- 31) ms respectively, both P < 0.05 ]; (2) The PJ interval in Group B was shortened to different extents. The PJ interval values in 4 patients with first degree atrioventricular block were shortened, but still beyond normal extent. The PJ interval values in 4 patients with bundle branch block were shortened to normal extent. CONCLUSION: If the pre-excitation syndrome patients have normal atrioventricular conduction the PJ interval is normal or the PJ interval may be shortened. If the patients have prolonged atrioventricular conduction, the PJ interval may be shortened by the pathway prograde conduction. PJ interval prolongation indicates atrioventricular conduction delay or ventricular conduction block, but bundle branch block cannot be excluded when the PJ interval is normal.

[Ventricular pre-excitation: electrophysiopathology, criteria for interpretation and clinical diagnosis. References for geriatrics]. / La pre-eccitazione ventricolare: elettrofisiopatologia, criteri interpretativi e inquadramento clinico. Riferimenti di Geriatria.

The authors review the state-of-the-art on ventricular pre-excitation in medical and arrhythmological literature in order to facilitate the recognition of the various clinical forms, like classic and occult Wolff Parkinson withe syndrome and Lown Ganong Levine syndrome. A historical introduction reviews our electrophysiopathological knowledge of the electrical activation and conduction of ventricular pre-excitation compared to normal, starting from the anatomic discovery of conduction pathways to the possible use of transesophageal electrostimulation and endocavity mapping to study electric potentials. Avantgarde technologies have also been developed to eliminate anomalous pathways firstly by using a direct current dirscharge and secondly radiofrequency. Atrioventricular electric activation has been widely illustrated in normal subjects in order to create a model for comparison with pathological ventricular pre-excitation: the upper left portion of the septum is no longer the first zone to trigger the kinetic mechanism compared to the early fascicular fraying of the homonymous branch. Instead the upper right part of the septum is activated earlier owing to the anomalous fascia connected on this side to the right branch through their septal arborisations. As a result, this new conduction pathway activates the ventricular masses earlier through an anomalous route, given that there is no further contact with the atrioventricular nodes which act as a control. A similar situation is found in the left branch block where the ventriculogram is late with a normal PR, unlike pre-excitation when an early delta wave is present with a short PR. Electric conduction is also illustrated based on new knowledge of the circuit structures and the rings theory. Orthodromic tachycardia is distinguished from the antidromic form, double accessory pathway tachycardia, ectopic reciprocant atrial fibrillation tachycardia and occult bundle tachycardia which is studied using transesophageal stimulation with a time threshold of 70 ms for ventricular-atrial retrograde activation. The stimulation techniques using single or repeated extrastimulus are explained for this purpose, as well as those with serial extrastimulation and the physical characteristics of the circuit based on the ratio between voltage and resistance. The authors also report the practical aims of electrostimulation for determining the electric threshold of the anomalous circuit in terms of refractoriness, electric atrial stability, reciprocity and the occurrence of the macro re-entry. Lastly, the authors describe electric conduction by anomalous pathways based on the criterion of conduction and activation, both of which are analysed and compared on the basis of the intrinsicoid deflection morphology on the surface ECG: the aberrant qRs usually suggests an antidromic ventricular activation and retrograde conduction between atrium and ventricle, while normal intrinsicoid deflection demonstrates that the activation is orthodromic and the conduction anterograde, namely ventricle-atrial. Having been reproduced in a synoptic synthesis, these manifestations show a regular electrophysiological pattern because they are dissimilar from the behaviour of the monophasic bioelectric potential of the cardiac cells specialised in the conduction of the stimulus, whether they represent a normal or pathological electric pathway. The study is rounded off by the analysis of the reciprocant tachycardias and their re-entry varieties related to the type of the anomalous bundles. A number of types of re-entry can be identified: sinusal re-entry (micro re-entry), atrial re-entry, re-entry in the atrio-ventricular node, re-entry tachycardia and the so-called triggered type. The discussion of the electrophysiopathological aspects of pre-excitation is followed by the clinical forms of ventricular pre-excitation that can be divided into 3 main types. The different ECG clinical pictures are set out in the summary table, together with the type of shunt and activation and possible variants, following Rosenbaum s classic paint: the common type B, the rare type A and a last variant, the C type. This section also describes the positional peculiarities of the Kent-Paladino bundle, the left ventricular, septal (anterior and posterior) and the multiple-bundle ones. The authors also illustrate the criterion and meaning of endocavity mapping in the search for anomalous bioelectric potentials that identify the pathway or the location of the endocardiac bundle and/or foci to be eliminated. A new echocardiographic technique is described with a conventional M mode, digitalised 2D and tissular Doppler which has a comparable ability to identify the anomalous pathways of electric conduction using a non-invasive method. (ABSTRACT TRUNCATED)