Successful ablation of a right atrium−axillary ventricular accessory pathway associated with Wolff‐Parkinson‐White syndrome

We report a case of a patient with right axillary ventricular. Similar congenital anomaly of the right atrium was reported as “right appendage diverticulum or right atrial diverticulum.” However, this independent chamber has its own annulus, synchronizes with the right ventricular, and generates large ventricular potential. Under the guidance of the CARTO mapping system (Biosense Webster, Diamond Bar, CA, USA), a right atrioventricular accessory pathway associated with type B Wolff‐Parkinson‐White syndrome was ablated successfully. This pathway was close to the annulus of the axillary ventricular. The patient remained free of arrhythmia at 1‐year follow‐up.     

Risk Factors of Adverse Presentation as the First Arrhythmia in Wolff‐Parkinson‐White Syndrome

Background: The aim of the study was the evaluation of the predictors of adverse presentation as first arrhythmia in Wolff‐Parkinson‐White syndrome; they usually affect young patients with septal or multiple accessory pathways (AP). Methods: Our population comprised 645 patients with a preexcitation syndrome. Among them, adverse presentation (sudden death, hemodynamically not tolerated atrial fibrillation [AF]) occurred in 60 (9%) (group I). Their clinical and electrophysiological features were compared to group II patients, which consisted of 75 patients with syncope (IIa), 287 with reentrant tachycardia (RT) (IIb), 211 asymptomatic patients (IIc), and 12 with well‐tolerated AF. Results: Sixteen group I patients had triggering factors. Group I patients were older (40 ± 18.5) than group II (34 ± 16) (P = 0.02). Male gender was as frequent in both groups (63%, 59%). Free wall left AP was more frequent in group I (65%) than in group II (37%) (P < 0.001), septal AP less frequent (27% vs 47%) (P = 0.004), multiple APs exceptional. RT was more frequent in group I (57%) than in group IIc (12%) (P < 0.001), less frequent than in group IIb (90.5%) (P < 0.001). AF was more frequent in group I (85%) than in group IIc (22%), or IIb (19%) (P < 0.001). Maximal rate through AP was higher in group I than in group II (P < 0.001). Conclusions: Adverse presentation in WPW may affect patients older than 35 years of both sexes, with a single free wall lateral AP. All could have been identified by an electrophysiological study. (PACE 2010; 33:1074–1081)     

Risk Stratification in Wolff‐Parkinson‐White Syndrome: The Correlation Between Noninvasive and Invasive Testing in Pediatric Patients

Background: In Wolff‐Parkinson‐White (WPW) syndrome, rapid antegrade conduction of atrial tachyarrhythmias can result in ventricular fibrillation and sudden death. Antegrade conduction can be assessed through noninvasive testing or invasive electrophysiology study (EPS). We aimed to determine the correlation between noninvasive testing and EPS in a pediatric WPW population. Methods: All WPW patients <21 years who underwent EPS over a 10‐year period were identified. Noninvasive testing reviewed included electrocardiogram, Holter, and exercise stress test (EST). Patients were classified as low‐risk if preexcitation was lost during any test. EPS data reviewed included antegrade conduction during atrial pacing and atrial fibrillation. Conduction through the accessory pathway (AP) to a cycle length ≤250 ms was considered rapid, otherwise patients were nonrapid. Sensitivity, specificity, positive (PPV), and negative predictive value (NPV) of noninvasive testing to correctly identify nonrapid conduction was calculated. Results: There were 135 EPS. Twenty‐four patients (18%) were classified low‐risk noninvasively. Two of the 24 (8%) had rapid conduction at baseline EPS. The sensitivity, specificity, PPV, and NPV of low‐risk noninvasive testing to predict nonrapid conduction was 22%, 94%, 92%, and 31%, respectively. Sixteen of the 24 had low‐risk EST and none had rapid conduction at baseline EPS. The specificity and PPV of low‐risk EST were 100%. Conclusion: Loss of preexcitation during noninvasive testing had high specificity and PPV for nonrapid antegrade conduction during baseline EPS. Abrupt loss of preexcitation during EST was a highly reliable noninvasive marker of nonrapid AP conduction at baseline in our pediatric WPW patients. (PACE 2012;35:1451–1457)     

Radiofrequency Catheter Ablation of Idiopathic Ventricular Tachycardias in Children

We performed radiofrequency catheter ablation of idiopathic ventricular tachycardia in six children. In four, the ventricular tachycardia originated in the left ventricle, in two it originated in the right ventricular outflow tract. In 5/6 (83%) the RF procedure was successful; there were no complications.     

High‐Amplitude Pace Mapping Increases Safety of Radiofrequency Catheter Ablation of Parahisian Ectopic Foci

Background: The objective of the study is to assess the efficacy of high‐amplitude pace mapping in terms of the atrioventricular (AV) block risk after radiofrequency catheter ablation (RCA) of parahisian ectopic foci. Methods: Twenty patients aged 38 ± 14 years with no structural heart disease underwent RCA of parahisian ectopic foci. All the patients were randomized into two groups: Group I (n = 11) had RCA performed in the region defined as ectopic focus by electrophysiology study and Group II (n = 9) had high‐amplitude pacing performed in the region of “perfect” mapping. RCA was done only at the sites where high‐amplitude pacing revealed the absence of His bundle capture. Results: In group I, the efficacy of RCA was 54.5% and it was 100% in group II (P = 0.0195). Group II had no complications; in group I there were 27% of AV blocks (P = 0.0893). The late recurrence of ectopic activity was comparable in both groups: 3 (27%) and 2 (22%), respectively (P = 0.7953). In all the cases of recurrent ectopic activity and in all the cases of ineffective primary procedure, group I had effective reablation procedures performed using high‐amplitude pace mapping. The overall efficacy in terms of repeated procedures was 90%. Conclusion: High‐amplitude pace mapping increases primary and secondary efficacy of parahisian ectopic foci RCA and decreases the risk of AV block development. (PACE 2012;35:1458–1463)     

Temperature Guided Radiofrequency Catheter Ablation of Myocardium: Comparison of Catheter Tip and Tissue Temperatures In Vitro

Temperature monitoring during RF ablation has been proposed as a means of controlling the creation of the lesion. However, in vivo studies have shown poor correlation between lesion size and catheter tip temperature. Thus, we hypothesized a difference between catheter tip and tissue temperatures during RF catheter ablation, and that this difference may depend on flow passing the ablation site, tip electrode length, and catheter-tissue orientation. In vitro studies were performed using four different ablation catheters (tip electrode length: 2, 4. or 6 mm) with a thermistor or a thermocouple as temperature sensor. Set temperature was 70°C and pulse duration was 30 seconds. Pieces of porcine left ventricle were immersed in a bath of isotonic saline-dextrose solution at 37°C. The ablation catheters were positioned perpendicularly, obliquely, or parallel to the endocardium. A temperature sensor was inserted from the epicardial side and positioned 1 mm beneath the catheter-tissue interface. Experiments were made with a flow of 200 mL/min passing the ablation site or with no flow. The catheter tip and tissue temperatures differed significantly (P < 0.0001) during ablation. This difference increased with time, with flow passing the ablation site, with the length of the tip electrode, and when the catheter was positioned perpendicularly or obliquely to the endocardium as compared to the parallel catheter-tissue orientation (P < 0.05), In conclusion, the tissue temperature may far exceed the catheter tip temperature, and intramyocardial superheating resulting in steam formation and popping may occur despite a relatively low catheter tip temperature. (PACE 1997; 20[Pt. I]:1252-1260)     

Should Radiofrequency Current Ablation be Performed in Asymptomatic Patients with the Wolff-Parkinson-White Syndrome?

The exiting new method of ablation of accessory pathways using radiofrequency current applied by catheters will dramatically change our therapeutic decisions in these patients in the near future. This brief survey reviews the existing literature about the risk of the disease as well as of the procedure of catheter ablation. From these data, the risk of sudden death appears to be extremely low in asymptomatic Wolff-Parkinsan-White (WPW) individuals. Side effects of catheter ablation may result from the invasive procedure as well as from radiation exposure (the latter to the patienl as well as to operating physicians). While the complication rate in experienced centers is extremely low, a multicenter registry of the success and complication rate is urgently needed in view of the many centers starting with catheter ablation. Based on a subjective benefit-to-risk analysis, asymptomatic WPW individuals should be offered catheter ablation only under special circumstances (high risk profession, athletes, family history of sudden death). On the other hand, catheter ablation need not be and should not be considered generally in asymptomatic individuals with WPW pattern. Finally, this author cannot imagine that the energy, time, and money spent for mass screening and eventual catheter ablation of asymptomatic WPW individuals with its attending risks can be outweighed by the potential benefits for these asymptomatic individuals.