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The optimal screening strategy to prevent sudden cardiac death (SCD) in athletes remains unknown. Pre-participation screening with electrocardiogram (ECG) remains controversial. The utility and accuracy of limb-lead (LL) ECG alone in identifying cardiac abnormalities associated with SCD has not been studied. This study was a comparative secondary data analysis, comparing the interpretation accuracy of 4 physicians evaluating publicly available ECGs of the most common cardiac conditions associated with SCD in athletes. Each physician interpreted a total of 100 ECGs: 50 normal ECGs (25 LL and 25 standard 12L) and 50 abnormal ECGs (25 LL and 25 standard 12L). The agreement between LL ECGs and 12L ECGs was assessed by Cohen's kappa coefficient and the accuracy of identifying an abnormal ECG was compared across LL and 12L ECGs using a chi-squared test. Inter-rater reliability was assessed by estimating the Fleiss's kappa coefficient. The sensitivity of LL ECG and 12L ECG was identical at 86%. The specificity of LL ECG was 75% (95% CI = 65% to 83%) and 12L ECG was 82% (95% CI = 73% to 89%). Substantial agreement was seen between LL ECG and 12L ECG interpretation across all readers (k = 0.63; 95% CI = 0.49 to 0.77). Interpretation accuracy was 81% (95% CI = 74% to 86%) and 84% (95% CI 78% to 89%) using LL ECG and 12L ECG, respectively (p = 0.43). In conclusion, the accuracy, sensitivity, and specificity were high and comparable for both LL ECG and 12L ECG in identifying cardiovascular conditions associated with SCD. Agreement between LL ECG and 12L ECG was substantial.

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.

Described herein is a 52-year-old man with Wolff-Parkinson-White syndrome and noncompaction cardiomyopathy who underwent 4 sternotomies to correct complications of 3 ablation procedures (2 open) for recurring supraventricular tachycardia, mitral valve repair for a damaged mitral valve during the third radiofrequency ablation procedure, and finally orthotopic heart transplantation.

Danon disease is an X-linked disorder with the clinical triad of cardiomyopathy, skeletal myopathy, and mental retardation. Early diagnosis of this disease remains a challenge, especially in the pediatric population. In this study, we developed a targeted panel-based next generation sequencing pipeline to identify mutations by sequencing of selected candidate genes in 136 pediatric patients with either hypertrophic cardiomyopathy (HC) or idiopathic dilated cardiomyopathy (IDC). This led to the identification of lysosome-associated membrane protein 2 (LAMP2) mutations in 4 of the 64 (6%) probands with HC, including 3 novel nonsense mutations (p.Q240X, p.S250X, and p.G22X). No LAMP2 mutation was detected in the other 72 probands with IDC. All 4 probands and one additional affected family member (2 men and 3 women) had an early-onset age and presented either HC alone or combined with Wolff-Parkinson-White syndrome and skeletal myopathy. Immunofluorescence staining and Western blot analysis revealed absent LAMP2 expression in both cardiac and skeletal muscle samples of the first proband and severely decreased LAMP2 expression in the skeletal muscle samples of the second proband. In conclusion, cardiomyopathy in the patients with Danon disease may occur during early childhood and tend to be HC rather than IDC in both affected men and women. Therefore, Danon disease should be considered as one of the leading causes of unexplained ventricular hypertrophy in pediatric patients. The inclusion of LAMP2 gene in cardiomyopathy genetic screening panels may contribute to early diagnosis of Danon disease.

To assess the mid-term mortality and risk of atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HC) and Wolff-Parkinson-White (WPW) syndrome, 40 patients with HC and WPW were enrolled in our center between 2010 and 2017. An age- and gender-matched comparison cohort of patients with HC without WPW (n = 160) was generated from the same center. The clinical profile and outcomes were assessed. Of 40 patients with WPW, 28 underwent accessory pathway (AP) elimination. Two patients (7%) had failed in AP elimination. During mid-term follow-up, 1 patient had an implantable cardioverter-defibrillator intervention. Fourteen patients had AF. A previous history of AF (hazard ratio [HR]: 4.69; 95% confidence interval [CI] 1.51 to 14.63) and left atrial dimension (HR: 1.12; 95% CI 1.03 to 1.23) at baseline were risk factors for AF occurrence during follow-up. The AP elimination significantly reduced risk for the incidence of AF (HR: 0.22; 95% CI 0.06 to 0.83). Compared with the control group, the prevalence of syncope and AF were significantly higher in the WPW group. During follow-up, no difference was identified in outcome measures consisting of all-cause death, cardiac transplantation, and implantable cardioverter-defibrillator intervention. A previous history of AF (HR: 5.20; 95% CI 2.63 to 10.30, p0.001) and persistent existing WPW (HR: 3.64; 95% CI 1.63 to 8.11, p = 0.002) were independent risk factors for AF occurrence during follow-up in the entire cohort. In conclusion, although WPW was uncommon and might not be correlated with mid-term mortality in HC patients, WPW might increase the risk of AF occurrence. Additionally, AP elimination may reduce the risk of AF occurrence.

Wolff-Parkinson-White (WPW) syndrome carries a risk for symptomatic arrhythmias and sudden death. The aim of this study was to examine the natural history of patients with Wolff-Parkinson-White syndrome diagnosed in childhood followed longitudinally at a single institution. The study population consisted of 446 patients. The median age of diagnosis was 7 years, and 61% were male. Associated heart disease was present in 40 patients (9%). Modes of presentation included supraventricular tachycardia (38%), palpitations (22%), chest pain (5%), syncope (4%), atrial fibrillation (0.4%), sudden death (0.2%), and incidental findings (26%); data were unavailable in 4%. During the study period, a total of 243 patients (54%) had supraventricular tachycardia, and 7 patients (1.6%) had atrial fibrillation. Of patients who presented at ≤3 months of age, 35% had resolution of manifest preexcitation compared with 5.8% who presented at3 months of age (p0.0001). There were 6 sudden deaths (1.3%), with an incidence of 2.8 per 1,000 patient-years. Two of these patients had structurally normal hearts (incidence 1.1 per 1,000 patient-years). Four of these patients had associated heart disease (incidence 27 per 1,000 patient-years) (p0.01). In conclusion, in a large population of patients with Wolff-Parkinson-White syndrome diagnosed in childhood, 64% had symptoms at presentation, and an additional 20% developed symptoms during follow-up. There were 6 sudden deaths (1.3%), with an overall incidence of 1.1 per 1,000 patient-years in patients with structurally normal hearts and 27 per 1,000 patient-years in patients with associated heart disease.

The gradual loss of ventricular preexcitation during exercise stress testing (EST) has an unclear risk of an association with life-threatening arrhythmia and could be related to the accessory pathway (AP) location. We compared the loss of preexcitation during EST with the risk assessment during invasive electrophysiology testing and determined whether the loss of preexcitation correlates with the AP location. We retrospectively reviewed patients aged ≤21 years with ventricular preexcitation who had undergone both EST and an electrophysiology study. The patients were divided into 3 groups: sudden loss (SL), gradual loss (GL), or no loss (NL) of preexcitation during EST. A total of 76 patients were included, with 11 (14%) in the SL group, 18 (24%) in the GL group, and 47 (62%) in the NL group. The SL group demonstrated a longer cycle length with 1-to-1 conduction by way of the AP during incremental atrial pacing compared with the NL group (375 ± 135 ms vs 296 ± 52 ms, p = 0.002), with no difference between the GL and NL groups (325 ± 96 vs 296 ± 52 ms, p = NS). Of the patients with 1-to-1 AP conduction of

The characteristics of multiple accessory pathways in children have not been previously studied. Records were reviewed of 317 consecutive pediatric patients with Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency catheter ablation at our institution. Twenty-eight patients (9%) had multiple pathways (a total of 64 pathways: 21 patients had 2, 6 had 3, and 1 patient had 4 pathways). The locations were left free wall (22 pathways), right free wall (19 pathways), posteroseptal (17 pathways), and anteromidseptal (6 pathways). Of these 64 pathways, 55 were ablated successfully without complications, 5 failed ablation, and 4 fasciculoventricular fibers did not require treatment. Three patients had a newly found pathway at the repeat session. Three patients had atrioventricular nodal reentrant tachycardia and the slow pathway area was modified. One patient had failed initial ablation and had a successful ablation using a 3-dimensional electroanatomic mapping system. Compared with patients with a single pathway, those with multiple pathways exhibited a higher incidence of antidromic tachycardia, a shorter anterograde accessory pathway effective refractory period (

Forty-four consecutive patients with Wolff-Parkinson-White syndrome and a left-sided accessory pathway were randomized to either a single-catheter transaortic or a single-catheter transseptal approach. The transseptal approach resulted in decreased procedural duration, radiation exposure, and radiofrequency lesions compared with the transaortic technique.

Wolff-Parkinson-White-type ventricular preexcitation was recognized for the first time in a 67-year-old man four days after aortic valve replacement. The preexcitation was intermittent.

Information on the long-term results of radiofrequency catheter ablation in a large group of patients with multiple accessory pathways (APs) was not available. This study included 858 patients with Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency catheter ablation: 73 patients (8.5%) had multiple APs. Sixty-six patients had 2 APs, 5 had 3 APs, 1 had 4 APs, and 1 had 5 APs. The most common combination pattern of these pathways were concealed APs (38 patients, 52%). Localization of accessory pathways showed a higher incidence of right free wall (22% vs 11%, p0.05), anteroseptal, and midseptal APs (9% vs 5%, p0.05) in patients with multiple APs than in patients with 1 AP. The most common anatomic sites for multiple APs were 2 APs in the left wall (21 patients, 28%). Although the success rate was similar (98% vs 99%, p0.05), procedure time (3.1 +/- 1.2 vs 2.0 +/- 1.1 hours, p0.05) and radiation exposure time (48 +/- 26 vs 29 +/- 19 minutes, p0.05) were longer in patients with multiple APs. The recurrence rate was higher in patients with multiple APs (9.5% vs 2.5%, p0.05), and the most common site of recurrent APs was in the left free wall (7.2%); in contrast, it was in the right free wall in patients with 1 AP. These findings demonstrated that a high success rate of radiofrequency catheter ablation was found in patients with multiple APs; however, the higher recurrence rate in patients with multiple APs should be considered.

Radiofrequency catheter ablation of left-sided accessory pathways (APs) with the use of an endocardial technique carries all potential risks of left heart catheterization. We analyzed the determinants of success, efficacy, and safety of radiofrequency catheter ablation from the coronary sinus (CS), as a potential alternative to the endocardial technique in these patients. Thirteen patients (mean age 40 ± 20 years) with 15 left-sided APs and a history of symptomatic supraventricular tachycardia were included in the study. Nine APs were localized in the left posteroseptal region, and the remaining 6 in the left free wall. Ablation from CS was attempted in 12 patients with 14 APs. In 1 patient ablation within the CS was not deemed safe because of a small venous lumen. All 14 APs were successfully ablated using either CS ablation alone or combined with the endocardial technique. Efficacy of the CS ablation as a primary technique was 56% (5 of 9 APs). In 5 additional APs, oblation in the CS eliminated pathway conduction after failed endocardial attempts. CS ablation either as a primary or a secondary technique eliminated conduction in 10 of 14 APs (71.4%) (group 1). In the remaining 4 APs (group 2), the primary CS attempt was unsuccessful and APs were ablated with a subsequent endocardial approach. Determinants of success for the CS method were local AP to atrial and/or ventricular electrogram amplitude ratios ≥ 1 (p < 0.05). The success rate of CS ablation was 83% in the left posteroseptal APs adjoining the branching point of the middle cardiac vein or a CS anomaly. Radiofrequency ablation in the CS was safe at the energy levels and durations used in this study, with no evidence of major or delayed vascular complications. During follow-up of 10 ± 7 months, there was no recurrence of sustained tachycardia in any patient who underwent successful ablation from the CS. We conclude that primary CS ablation can be an effective and safe alternative to the endocardial technique for ablation of leftsided APs with electrogram ratios ≥ 1. These findings are frequently seen in left posteroseptal APs in proximity to the middle cardiac vein or a CS anomaly.

Prediction of accessory pathway location before radio-frequency ablation has become increasingly important for patients with Wolff-Parkinson-White syndrome. However, existing electrocardiographic (ECG) criteria for localization of accessory pathways have several limitations, and the polarity of delta waves has not been well defined. In the present study, 369 patients with a single anterogradely conducting accessory pathway who underwent successful radiofrequency ablation were included. The polarity of delta waves was defined and categorized in detail, and various ECG characteristics of the most preexcited QRS complexes were examined and compared with QRS complexes after successful ablation in the initial 182 patients, which included morphology and polarity of delta waves, initial 20, 40, and 60 ms segments of the preexcited QRS complex, R/S ratio in the precordial leads, R/S ratio in the frontal leads, delta wave axis in the frontal plane, polarity of delta waves in the frontal leads, and polarity of delta waves in the precordial leads. The polarity of the initial 40 ms segment of the most preexcited QRS complexes in each of the frontal leads, and the polarity of the initial 60 ms segment of the most preexcited QRS complex in each of the precordial leads proved to be the best representatives of delta wave polarity in the respective leads.(ABSTRACT TRUNCATED AT 250 WORDS)

A new algorithm (St. George's algorithm), based on the polarity and morphology of QRS complexes rather than delta waves, was developed for localizing accessory pathways to 1 of 9 sites on the atrioventricular annuli. This was compared with algorithms previously proposed by Skeberis et al (localizing to 1 of 7 sites) and Milstein et al (localizing to 1 of 4 sites). The preexcited 12-lead electrocardiograms recorded during sinus rhythm in 106 consecutive patients (including 60 retrospectively analyzed patients and 46 prospectively analyzed patients) who underwent successful radiofrequency catheter ablation of a single accessory pathway were analyzed by 3 blinded observers using all 3 algorithms. The results were compared with the actual localization of accessory pathways as derived from endocardial mapping during catheter ablation. In all 106 patients, the accuracy of the 3 algorithms for 4 sites on the atrioventricular annuli (as considered by Milstein's method) was 72%, 79%, and 92% for Milstein's, Skeberis', and St. George's algorithms, respectively. For 7 sites (as considered by Skeberis' method), the accuracy was 65% (Skeberis' algorithm) and 88% (St. George's algorithm), and for 9 sites (as considered by our method) the accuracy was 86% (St. George's algorithm). In 46 prospectively analyzed patients, the accuracy of the 3 algorithms for 4 sites was 70% (Milstein's), 67% (Skeberis'), and 87% (St. George's); for 7 sites the accuracy was 61% (Skeberis') and 85% (St. George's), and for 9 sites the accuracy was 85% (St. George's). The reproducibility of St. George's and Skeberis' methods was better than that of Milstein's method.(ABSTRACT TRUNCATED AT 250 WORDS)

Fourteen patients (5%) with an intermediate septal accessory pathway were identified among 283 consecutive patients with the Wolff-Parkinson-White syndrome who had electrophysiologic study and radiofrequency ablation therapy. Nine were women and 5 were men (mean age 33 +/- 13 years). The resting electrocardiogram showed ventricular preexcitation in 8 patients and normal PR interval in 6. Anterograde and retrograde mapping studies revealed that the accessory pathway was para-Hisian in 11 patients and paranodal in 3. The accessory pathway was successfully ablated in 10 patients (9 para-Hisian and 1 paranodal) and damaged in 1 (para-Hisian). Treatment of 3 patients was complicated by transient atrioventricular (AV) block, of 1 by intermittent second-degree AV block, and of another by permanent complete AV block requiring implantation of a permanent pacemaker. Six patients underwent a follow-up electrophysiologic study 84 +/- 55 days after ablation; none had induction of tachycardia even after isoproterenol infusion. It is concluded that radiofrequency ablation therapy for intermediate septal accessory pathway is feasible. However, the success rate is only modest (71%), whereas complications with heart block (36%) or complete right bundle branch block (29%) are high. Thus, the procedure should be reserved for patients with life-threatening or troublesome symptomatic tachyarrhythmias.

Percutaneous ablation of accessory pathways was performed in 22 consecutive children and adolescents (9 boys and 13 girls, age range 8 to 18 years). Low-energy direct current (DC) was used exclusively in the first 6 patients, whereas ablation was performed with radiofrequency energy in the following 16. Accessory pathways were located in the left free wall in 15 patients, were posteroseptal in 3, were in the right free wall in 3 and were anteroseptal in 1. A concealed accessory pathway was present in 7 patients (32%). There was no significant difference in clinical or electrophysiologic variables between both groups. Catheter ablation was successful in the initial 6 patients using low-energy DC, as compared with 13 of 16 patients using radiofrequency ablation. Low-energy DC was successful as a backup power source in all 3 patients who had unsuccessful radiofrequency ablation. There was no complication. The median procedural and fluoroscopic times for successful ablation were 2.5 hours and 49 minutes, respectively (p = NS between both power sources). Accessory pathway conduction recurred in 2 patients (33%) who had low-energy DC as compared with 1 (6%) who had radiofrequency ablation (p = NS). These 3 patients had successful reablation of their accessory pathways. In children and adolescents with accessory pathways, both new power sources compare favorably, with an overall success rate of ablation of 100% (22 of 22 patients). Radiofrequency ablation should be used initially because it does not require general anesthesia and is associated with a lower rate of recurrence of accessory pathway conduction. Low-energy DC may be most useful as a backup in patients who initially have unsuccessful radiofrequency ablation.

Congenital heart disease complicates the management of most accessory pathway-mediated tachycardias and also increases the challenge of radiofrequency ablation. Since 1990, radiofrequency ablation of accessory atrioventricular (AV) pathways has been attempted in 10 patients (age range 3.5 months to 30 years) with congenital heart disease: Ebstein's anomaly (n = 5), heterotaxy with AV discordance (n = 3), tetralogy of Fallot (n = 1) and total anomalous pulmonary venous return (n = 1). Eight patients had manifest Wotff-Parkinson-White syndrome and 2 had concealed pathways. Five patients had multiple pathways including 4 of the 5 with Ebstein's anomaly. Of 16 pathways total, 15 were associated with the tricuspid valve including all pathways in the patients with Ebstein's anomaly and heterotaxy. The His bundle area was identified in all patients and involved an anterior AV node in 2 of 3 with heterotaxy. Ablation was performed on the atrial side of the AV ring in all cases. No instance of AV block was encountered. Complete success was achieved in 6 patients including the 3 with heterotaxy. In 2 patients, manifest preexcitation was eliminated and clinical symptoms were greatly modified. The procedure was transiently successful in 1 patient who later had surgical interruption of the accessory pathway during tetralogy of Fallot repair. Ablation was unsuccessful in 1 patient. Thus, the overall success was 80%.

Figure 1. This is patient BH’s 3-lead ECG that was published in the original article. The original caption should read right bundle branch block as the authors explained in their text. One of the most significant articles in the history of cardiology was published in 1930 under the rather unassuming title, Bundle-branch block with short P-R interval in healthy young people prone to paroxysmal tachycardia. The authors, whose names would be joined to form a wellknown eponym, were Louis Wolff of Boston, John Parkinson of London, and Paul Dudley White of Boston. White was very interested in the long-term follow-up of patients that he had seen during his half-century career. In his 1967 book on the long-term follow-up of patients with various types of cardiovascular disease, White reported on 2 of the 11 patients that he and his coauthors had described in their original Wollf-Parkinson-White article. White explained that 1 of those patients was a physician who was in good health 36 years after the report was published. As a result of a chance encounter, I discovered that 1 of Wolff, Parkinson, and White’s original 11 patients was alive and well until he developed heart failure and died at the age of 83, >7 decades after they summarized his case in their classic article. BH was 11 years old when he was seen by Dr. (later Sir) John Parkinson at the London Hospital on April 13, 1929. The boy had a history of exhaustion, occasional pallor, and a varying pulse rate that was often slow. For a year he had had recurrent attacks lasting a few days at a time in which he was pale with a pulse rate of 40 to 65 beats/min. His blood pressure, cardiac examination, and orthodiagram (a special type of chest x-ray) were normal. The boy’s electrocardiogram (ECG) showed a short PR interval of

To evaluate and compare the safety and efficacy of catheter-mediated direct-current (DC) or radio-frequency (RF) ablation in patients with free wall accessory atrioventricular pathways, 95 patients with free wall accessory atrioventricular pathway-mediated tachyarrhythmias underwent catheter ablation. Immediately after ablation, 27 of 30 accessory pathways (90%) were ablated successfully with DC, but 2 of the 27 had early return of conduction and received a second ablation session; 3 of 8 (38%) and 57 of 62 (92%) accessory pathways were ablated successfully with RF through a small-tip (2 mm) and a large-tip (4 mm) electrode catheter, respectively. Complications in DC ablation included transient hypotension (2 patients) and pulmonary air-trapping (2 patients) and in RF ablation, cardiac tamponade (1 patient) and suspicious aortic dissection (1 patient); myocardial injury and proarrhythmic effects were more severe in DC ablation. Procedure and radiation exposure time were significantly longer in RF ablation (DC, 3.6 ± 0.2 hours, 34 ± 4 minutes; RF 4.2 ± 0.5 hours, 50 ± 10 minutes). This study confirms that RF ablation is associated with little morbidity and few complications, and RF ablation with a large-tip electrode catheter is an effective and relatively safe nonsurgical method for treatment of free wall accessory atrioventricular pathway-mediated tachyarrhythmias.

Atrial fibrillation in patients with Wolff-Parkinson-White (WPW) syndrome may lead to syncope, ventricular fibrillation, and sudden death. In a follow-up study of 241 patients with WPW syndrome in a relatively unselected population, 26 patients had documented atrial fibrillation (11%). These patients were followed up after 1-37 years (median 11 years; mean 15 years). During this period, 2 of 26 died suddenly. These 2 patients had the shortest RR interval during spontaneous atrial fibrillation (less than or equal to 220 msec), greater than or equal to 1 episodes of syncope, and a persistent delta wave in all available electrocardiograms. In comparison, sudden or tachycardia-related death was seen in 4 of the 241 patients. This difference is not statistically significant. Thus, atrial fibrillation of 26 patients with WPW syndrome was surprisingly well tolerated in our follow-up study with only 2 sudden deaths.

The effect of successful catheter ablation of overt accessory pathways on the incidence of atrial fibrillation (AF) was studied in 129 symptomatic patients with (n = 75) or without (n = 54) previous documented AF. Fourteen had had ventricular fibrillation. Factors predictive of recurrence were examined, including electrophysiologic parameters. Atrial vulnerability was defined as induction of sustained AF (greater than 1 minute) using single, then double, atrial extrastimuli at 2 basic pacing cycle lengths. When compared to patients with only reciprocating tachycardia, patients with clinical AF included more men (77 vs 54%, p = 0.008) and were older (35 +/- 12 vs 29 +/- 12 years, p = 0.01). They had a significantly shorter cycle length leading to anterograde accessory pathway block (252 +/- 42 vs 298 +/- 83 ms, p less than 0.001), greater incidences of atrial vulnerability (89 vs 24%, p less than 0.001) and subsequent need for cardioversion (51 vs 15%, p less than 0.001). After discharge, the follow-up period was 35 +/- 12 months (range 18 to 76); 7 patients with previous spontaneous AF (9%) had recurrence at a mean of 10 months after ablation. Age, presence of structural heart disease accessory pathway location, atrial refractory periods and accessory pathway anterograde conduction parameters were not predictive of AF recurrence. Persistence of atrial vulnerability after ablation was the only factor associated with further recurrence of AF. Atrial vulnerability was observed after ablation in only 56% of patients with previous AF versus 89% before ablation. It is concluded that successful catheter ablation of accessory pathways prevents further recurrence of AF in 91% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Propafenone, a class Ic antiarrhythmic agent, 1 has been shown to be effective in restoring sinus rhythm in patients with symptomatic orthodromic tachycardia associated with Wolff-Parkinson-White syndrome (WPW). 2,3 The high rate of conversion to sinus rhythm (>60%) is attributed to the relatively high dose administered (2 mg/kg). In addition, recurrence of tachycardia can be prevented in most cases. The effectiveness of the antiarrhythmic agent is usually tested at rest. Information concerning the pharmacologic effects of drugs during exercise in patients with supraventricular arrhythmias is scarce. In this study, the electrophysiologic effects of propafenone were examined in 10 patients with WPW at rest, during isoproterenol infusion and during exercise to evaluate its antiarrhythmic properties under these conditions.

Antidromic circus movement tachycardia was documented in 36 of 345 consecutive patients with Wolff-Parkinson-White syndrome undergoing detailed electrophysiologic evaluation. Twenty-six patients were men and 10 were women (mean age +/- standard deviation 26 +/- 12 years [range 12 to 45]). Multiple accessory pathways were identified in 12 of these 36 patients (33%). Ten of the patients (67%) with clinically documented antidromic tachycardia had multiple accessory pathways. Dizziness and syncope occurred in 61 and 50% of patients with antidromic circus movement tachycardia. Six patients had clinical documentation of atrial fibrillation, and 4 patients (11%) were resuscitated from ventricular fibrillation. In the 36 patients, 56 distinct antidromic tachycardias were recorded and several different pathways were observed. Orthodromic tachycardia was the most frequently associated arrhythmia (72%). Dual atrioventricular nodal pathways were present in 12 patients (33%); however, atrioventricular nodal tachycardia could be initiated in only 2 of them. Interruption of the accessory pathway was successfully performed in all 20 patients undergoing surgery.

In this retrospective study of 22 patients with the Wolff-Parkinson-White (WPW) syndrome, the cost of catheter ablation in 11 patients was compared with that of surgical ablation in another 11 patients. All patients in the catheter ablation group had a posteroseptal accessory pathway; in the surgical group, 5 patients had a left lateral accessory pathway, 3 had a left lateral and posteroseptal accessory connection and 3 had a right-sided pathway. Catheter ablation was successful in 8 of 11 patients (73%). In the surgical group, the accessory pathway was interrupted successfully in all patients (100%). The mean duration (+/- standard deviation) of hospitalization was 6 +/- 2 days in the catheter ablation group and 8 +/- 4 days in the surgical group. The mean cost/patient, expressed in 1988 dollar values, was +14,116 +/- 4,493 in the catheter ablation group and +34,175 +/- 5,434 in the surgical ablation group (p less than 0.0001). The mean time lost from work or school was 10 +/- 5 days in the catheter ablation group and 60 +/- 16 days in the surgical group (p less than 0.01). Catheter ablation is significantly less expensive than surgical ablation of accessory pathways. Assuming that all patients in whom catheter ablation is unsuccessful subsequently undergo successful surgical ablation, the mean cost of definitive therapy in the catheter ablation group (+24,382 +/- 4,741) is still significantly lower than the cost in the surgical group (+34,175; p less than 0.001). An additional economic advantage of catheter ablation is that the mean time lost from work or school is 10 days compared to 60 days with surgical ablation.

The effects of isoproterenol on accessory pathway conduction were evaluated in 24 patients with intermittent and 60 patients with concealed pre-excitation, using atrial and ventricular incremental and extrastimulus testing techniques. The atrial paced cycle length that induced block in the accessory pathway could be compared in 11 of the 24 patients with intermittent preexcitation before and after isoproterenol; it decreased from 622 +/- 212 ms to 408 +/- 128 ms (mean +/- standard deviation) after isoproterenol (p less than 0.01). The anterograde effective refractory period of the accessory pathway could be compared in 5 patients before and after isoproterenol; it decreased from 460 +/- 131 to 310 +/- 48 ms after isoproterenol (p less than 0.01). None of the 60 patients with concealed preexcitation showed ventricular preexcitation with isoproterenol infusion. Eighty-one of the 84 patients had clinically documented supraventricular tachycardia, suggesting the accessory pathway was capable of retrograde conduction. Retrograde study was performed in all 84 patients; 83 had retrograde conduction and the other had no retrograde conduction before and after isoproterenol. The ventricular paced cycle length that induced block in the accessory pathway could be compared in 38 patients before and after isoproterenol; it decreased from 342 +/- 71 to 296 +/- 39 ms after isoproterenol (p less than 0.001). The retrograde effective refractory period of the accessory pathway could be compared in 56 patients; it decreased from 293 +/- 76 to 238 +/- 36 ms after isoproterenol (p less than 0.001). In conclusion, isoproterenol facilitates anterograde and retrograde accessory pathway conduction, but the facilitation of anterograde conduction occurs only in those capable of spontaneous conduction.

Little is presently known regarding whether a rhythm-control or a rate-control strategy is more frequently used in patients hospitalized for atrial fibrillation (AF). This study was conducted to assess patient and physician characteristics associated with each treatment strategy and with the use of anticoagulants. Hospitalizations for primary diagnoses of AF were examined using hospital claims from January 2000 to December 2004. Patients who received antiarrhythmic drugs, ablation, or cardioversion for AF were categorized as receiving rhythm control. Patients managed only with beta blockers, calcium channel blockers, or digoxin were categorized as receiving rate control. Characteristics associated with rhythm compared with rate control and anticoagulant use with CHADS(2) score were determined. The study cohort included 155,731 hospitalizations from 464 hospitals. Of these, 75,397 (48%) were categorized as involving rhythm control and 80,334 (52%) as involving rate control. Care by a noncardiologist (adjusted odds ratio [OR] 0.33, 95% confidence interval [CI] 0.31 to 0.36) and increasing age65 years (adjusted OR 0.87, 95% CI 0.86 to 0.88) were associated with lower odds of rhythm versus rate control; hypertrophic cardiomyopathy was associated with greater odds (adjusted OR 2.3, 95% CI 1.81 to 2.84) of rhythm control. Warfarin use was greater in the rhythm-control group compared with the rate-control group (adjusted OR 1.56, 95% CI 1.52 to 1.60), and warfarin use was greater with a CHADS(2) scoreor =2 (unadjusted OR 1.21, 95% CI 1.19 to 1.24). In conclusion, rhythm- and rate-control strategies were used equally in patients hospitalized for AF. Some observations, such as greater use of the rate-control strategy with increasing age, were consistent with recommendations, but others, such as lower use of warfarin in the rate-control group, were not.

The anterograde effective refractory period of the accessory pathway is age-dependent in pediatric patients with the WPW syndrome. Thus, age should be considered when developing electrophysiologic criteria for the risk of hypotensive arrhythmias in these patients. In addition, general anesthesia must also be considered in interpreting age-related changes in the anterograde APERP, especially in children.

In a population of 690 patients with Wolff-Parkinson-White (WPW) syndrome referred to our hospital from January 1979 to February 1995, 15 patients (2.2%) had an aborted sudden death out of the hospital. This retrospective study examines their clinical and electrophysiologic characteristics. Gender, accessory pathway localization, and presence of multiple accessory pathways were compared between patients with and without spontaneous ventricular fibrillation (VF). Whereas gender and the presence of multiple accessory pathways did not significantly differ between both groups, septally located pathways occurred significantly more often in the VF group. In patients with aborted sudden death, spontaneous VF was found significantly more often in men (13 of 15). VF was the first manifestation of the WPW syndrome in 8 patients. The remaining 7 patients had documented episodes of atrial fibrillation, circus movement tachycardia, or both (n = 2). Ten of the 15 patients were exercising or under emotional stress at the time of aborted sudden death. Only 1 patient had 2 accessory pathways. The location of the accessory pathway was septal (midseptal or posteroseptal) in 11 patients, left lateral in 4, and right lateral in 1).

The high frame-rate tissue-velocity imaging method may be superior to the conventional M-mode method in accurately localizing accessory pathways without consuming large amounts of time.

1. Stampfer MJ. Estrogen replacement and coronary heart disease: a quantitative assessment of the epidemiologic evidence. Prev Med 1991;20:47–63. 2. Grodstein F, Stampfer MJ, Colditz GA, Willett WC, Manson JE, Joffe M, Rosner B, Fuchs C, Hankinson SE, Hunter DJ, Hennekens CH, Speizer FE. Postmenopausal hormone therapy and mortality. N Engl J Med 1997;336:1769– 1776. 3. Rossouw JE, Anderson GL, Prentice RL, LaCroix AZ, Kooperberg C, Stefanick ML, Jackson RD, Beresford SA, Howard BV, Johnson KC, Kotchen JM, Ockene J. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women’s Health Initiative randomized controlled trial. JAMA 2002;288:321–333. 4. Grady D, Herrington D, Bittner V, Blumenthal R, Davidson M, Hlatky M, Hsia J, Hulley S, Herd A, Khan S, et al. Cardiovascular disease outcomes during 6.8 years of hormone therapy. Heart and Estrogen/progestin Replacement Study follow-up (HERS II). N Engl J Med 2002;288:49–57. 5. Furberg CD, Vittinghoff E, Davidson M, Herrington DM, Simon JA, Wenger NK, Hulley S. Subgroup interactions in the Heart and Estrogen/progestin Replacement Study: lessons learned. Circulation 2002;105:917–922. 6. Kannel WB. Lipids, diabetes and coronary heart disease: insights from the Framingham study. Am Heart J 1985;110:1100–1107. 7. Kleinman J, Donahue R, Harris M, Finucane F, Madans J, Brock D. Mortality among diabetics in a national sample. Am J Epidemiol 1988;128:389–401. 8. Harris MI. Prevalence of diabetes and impaired glucose tolerance and plasma glucose levels in US population aged 20–74 years. Diabetes 1987;36:523–534. 9. Keating NL, Cleary PD, Rossi AS, Zaslavsky AM, Ayanian JZ. Use of hormone replacement therapy by postmenopausal women in the United States. Ann Intern Med 1999;130:545–553. 10. Gillum RF, Fortmann SP, Prineas RJ, Kottke TE. WHO criteria for diagnosis of acute myocardial infarction. Am Heart J 1984;108:150–158. 11. Hulley S, Grady D, Bush T, Furberg C, Herrington D, Riggs B, Vittinghoff E. Randomized trial of estrogen plus progestin for secondary prevention of coronary heart disease in postmenopausal women. Heart and Estrogen/progestin Replacement Study (HERS) Research Group. JAMA 1998;280:605–613.

diated tachycardia. 1‐4 However, a detailed analysis of the inter-relationships between gender, accessory pathway location, and the age of onset of accessory pathway-mediated tachycardia has been lacking. Therefore, the purpose of this study was to analyze the interactions between gender, accessory pathway location, and the age of onset of accessory pathwaymediated tachycardia. ••• The subjects of this study were 910 patients who underwent an electrophysiologic study at the University of Michigan Medical Center and met the following selection criteria: a history of symptomatic paroxysmal tachycardia; the ability to recollect the age of onset of the tachycardia; a single accessory pathway; an inducible accessory pathway-mediated tachycardia in the electrophysiology laboratory; and successful radiofrequency ablation of the accessory pathway. Patients who had 1 mechanism of tachycardia or 1 accessory pathway were excluded from the study. There were 536 men (59%) and 374 women (41%), and their mean age at the time of the electrophysiologic study was 37 15 years ( SD; range 10 to 84 years). The location of the accessory pathways was classified as being left sided, right sided, or septal, according to the site at which successful radiofrequency ablation was achieved. Among the 910 accessory pathways, 541 (59%) were left sided, 131 (14%) were right sided, and 238 (26%) were septal. In 328 patients (36%), the accessory pathway was concealed and capable only of retrograde conduction, and in the remaining 64% of patients, the accessory pathway was manifest and conducted in the anterograde direction. Continuous variables are expressed as mean 1 SD. Student’ s t test was used to compare 2 groups. Analysis of variance was used when comparisons involved 2 groups. When group differences were found, 1-way analysis of variance was followed by the

Doppler echocardiography of mitral inflow has enhanced our understanding of left ventricular (LV) diastolic function but multiple factors contribute to these velocity recordings, In addition to LV relaxation and compliance, variables such as age, heart rate, left atrial pressure and LV systolic function all interact to comprise the mitral inflow Doppler velocities. 1 The effects of altering atrioventricular (AV) delay on Doppler indexes of LV filling have only been examined in patients with sequential AV pacemakers and although these Doppler patterns are well documented, the beneficial hemodynamic eifects of an optimal AV delay are still debated. 2–5 To date, there has been no report on the effects of preexcitation and its abolition on mitral inflow patterns. Current techniques with radiofrequency ablation of accessory pathways has a high success rate in restoring normal AV conduction with minimal adverse effects on patients 6 and thus allows us to examine this question. We hypothesize that just as is seen with AV pacing, the mitral inflow patterns associated with a short AV interval during preexcitation are altered by normalization of the AV interval after radiofrequency ablation. In addition, we hypothesize that these changes may have beneficial hemodynamic effects by increasing stroke volume.

Preliminary reports suggest that radiofrequency catheter ablation is a safe and effective method for the management of supraventricular tachyarrhythmias in children. 1 Transesophageal echocardiography (TEE) has recently been used to monitor various interventional cardiac catheterization procedures in children. The use of single-plane TEE has been described in 2 patients (aged 43 and 16 years) with Wolff-Parkinson-White (WPW) syndrome and left-sided accessory pathways undergoing radiofrequency ablation. 2 The present report summarizes our experience with biplanar TEE monitoring and guidance of radiofrequency catheter ablation in children and adolescents. The report focuses on the feasibility, safety and potential benefits of the procedure.

Several recent publications have demonstrated a high success rate and few serious procedure-related acute complications with radiofrequency ablation of accessory atrioventricular (AV) pathways 1–3 However, the long-term consequences have not been well characterized. This procedure usually involves making 1 or more radiofrequency lesions at the accessory pathway's ventricular insertion site at the level of the AV groove. Segments of several of the major coronary arteries lie within the AV groove and could be damaged or thrombosed inadvertently by this procedure. Furthermore, each lesion creates a small scar that could be associated with new ventricular arrhythmias. 4 Because of these theoretic concerns, this study was designed to determine prospectively whether radiofrequency ablation of accessory pathways causes the development of inducible or spontaneous ventricular tachycardia or chronic alterations of coronary arterv anatomy.

Radiofrequency catheter ablation has become the treatment of choice for selected patients with paroxysmal supraventricular tachycardia due to atrioventricular node reentry or the Wolff-Parkinson-White syndrome. 1–3 Despite encouraging results described in several series, the optimal energy delivery strategy has not been defined. Lesion formation occurs during radiofrequency ablation as the result of resistive heating at the electrode-tissue interface.4 The magnitude of heat generation is proportional to power density at the point of contact.5 Electrosurgical units currently being used for radiofrequency ablation have a low source impedance and therefore approximate constant voltage sources. With such a device, one preselects a given output voltage. Applied power is proportional to the square of this output voltage and is inversely proportional to the load impedance imposed by the ablation catheter, patient and indifferent electrode. Thus, the effectiveness of any given energy application may be influenced by the impedance of the system. This study characterizes impedance during radiofrequency catheter ablation in humans, and defines the relation between clinical and ablation parameters, and measured impedance.

A association between atrial fibrillation (AF) and Wolff-Parkinson-White (WPW) syndrome has been recognized since the earliest description of the condition.1 AF has been documented in approximately 30% of patients with WPW syndrome,2 and it appears to be associated with faster atrioventricular reciprocating tachycardia (AVRT), shorter accessory pathway effective refractory periods, slower intra-atrial conduction, structural heart disease, and advanced age.2–4 Rates of cure of AF by ablation of the accessory pathway in some series have been .91%.4,5 Autonomic modulation of accessory pathway refractoriness and conduction became evident in experiments involving exercise,6 postural changes,7 and drugs.6,8 Timeand frequency-domain analysis of heart period variability performed in patients with paroxysmal AF suggests that autonomic modulation is important in selected patients.9,10 Assessment of autonomic balance using analysis of heart period variability in patients with WPW syndrome has not been performed. The purpose of this study was to determine if frequency-domain analysis of heart period variability can predict the occurrence of AF in patients with the WPW syndrome and identify characteristics of supraventricular tachycardia in this population. • • • The study included 22 consecutive patients with WPW syndrome who underwent electrophysiologic study and radiofrequency ablation of an accessory pathway. All 22 patients underwent 24-hour ambulatory Holter monitoring immediately before electrophysiologic study. The patients were studied .5 halflives after discontinuation of antiarrhythmic medications, including b blockers. Effective refractory periods and conduction characteristics of the accessory pathway were obtained by atrial and ventricular programmed stimulation before mapping and ablation of the accessory pathway. All patients underwent transthoracic echocardiography. Patients with evidence of structural heart disease, decreased left ventricular function, hypertension, and diabetes mellitus were excluded from this study. Three-channel 24-hour electrocardiographic recordings were analyzed using a Zymed 1600 digital scanner (Camarillo, California) with a sampling frequency of 192/s. The data were transferred to a computer for analysis of heart period variability using custom Zymed HRV software. All RR interval sequences were individually reviewed to ensure correct identification and classification of each QRS complex. Power spectral analysis using Fourier transformation was then performed providing spectral power (square milliseconds) in the low-frequency (LF) bandwidth of 0.04 to 0.15 Hz (believed to reflect both sympathetic and parasympathetic influences modulated by baroreflex activity) and the high-frequency (HF) bandwidth of 0.15 to 0.40 Hz (which primarily reflects vagal modulation).11 The LF/HF ratio (defined as the ratio between LF and HF spectral power) is believed by many investigators to represent a relative composite index of parasympathetic and sympathetic modulation.11 Power spectral values were analyzed before and after transformation to their natural logarithms (Ln) in view of their non-normal distributions. All data are expressed as mean 6 SD. The 2-tailed unpaired t test for independent variables was used in the analysis of continuous variables. Differences in categorical variables between the 2 groups were assessed using the chi-square or Fisher’s exact test. Bivariate analysis (Pearson’s correlation) was used to compare continuous numeric variables. A p value of ,0.05 was considered significant. Of the 22 consecutive patients enrolled in this study, 6 (27%) were male, and ages ranged from 12 to 57 years (mean 37 6 13) (Table I). After a careful medical history and chart review, paroxysmal AF was documented in 8 of 22 patients (36%) (group I) and was associated with continuous pre-excitation in all patients with a mean shortest pre-excited RR interval during AF of 234 6 79 ms. In 14 of 22 patients, no documentation or history of spontaneous AF was found (group II). During electrophysiologic study, AF was induced by programmed electrical stimulation in all patients in group I compared with only 3 of 14 (21%) patients in group II (p 5 0.001). The duration of induced AF was .30 minutes in 4 of 8 patients in group I; these patients required direct-current cardioversion. Of the 3 patients with inducible AF in group II, all of the episodes were self-terminating. The mean of the shortest pre-excited RR interval during AF was shorter in group I (243 6 39 ms) compared with group II (346 6 84 ms, p ,0.05). Orthodromic AVRT was induced in 6 of 8 patients in group I, who exhibited a mean cycle length of 335 6 75 ms compared with 9 of 14 patients in group II with a mean cycle length of 371 6 61 ms (p 5 NS). The average recording time for the entire group was 17:56 6 2:48 hours and did not differ significantly between group I (18:52 6 3:56 hours) and group II (17:23 6 1:46 hours) patients. The percent of complexes excluded from analysis because of noise was 2.0 6 2.4% in group I and 1.9 6 3.2% in group II (p 5 NS). In 8 patients with documented From the Department of Medicine, Montefiore Medical Center, Bronx, New York, and Albert Einstein College of Medicine, New York, New York; and the Department of Pharmacology, Columbia-Presbyterian Medical Center, College of Physicians and Surgeons, New York, New York. Dr. Ferrick’s address is: Division of Cardiology, Montefiore Medical Center, 111 East 210 Street, Bronx, NY 10467. Manuscript received July 22, 1999; revised manuscript received and accepted December 1, 1999.

••• Fifteen consecutive patients with Wolff-ParkinsonWhite syndrome (7 men and 8 women, aged 39 6 16 years) were included in the study group. Of these patients, VP was intermittent in 2 and persistent in the others. Eight patients with complaints of palpitation underwent electrophysiologic study and radiofrequency ablation of the accessory pathway. The ablation procedure was successful in 7 of these patients. The accessory pathways of the other 7 patients were located noninvasively by an electrocardiographic algorithm. 11 The control group was composed of 36 subjects (15 men and 21 women, aged 50 6 17 years) without 2-dimensional echocardiographic evidence of LV wall motion abnormality, including 20 controls without cardiovascular disease, 12 hypertensive patients, and 4 patients with diabetes mellitus. Exclusion criteria were conduction disturbance except VP and aortic regurgitation that interfered with the recording of IRF. All subjects were in sinus rhythm during Doppler examination. The study procedures were clearly explained to the patients and all agreed to participate. They received simultaneous recordings of electrocardiography, phonocardiography, and echo- cardiography. Only those with successful ablation of

Since September 1990, radiofrequency ablation 1,2 has replaced surgery as the curative treatment of choice for patients with Wolff-Parkinson-White syndrome in our institution. The patients are referred to surgery only if radiofrequency ablation is unsuccessful. However, in many institutions surgery remains the primary option for patients requiring curative treatment. It is not known whether or not patients with recurrent accessory pathway conduction after surgical ablation can be safely and successfully cured by radiofrequency ablation. In this communication we report our experience with successful radiofrequency ablation in 3 patients who had recurrent accessory pathway conduction after surgical ablation.

The degree of preexcitation in the Wolff-ParkinsonWhite (WPW) syndrome depends on the relative degree of ventricular activation through the accessory pathway and the atrioventricular nodal system. A minimal preexcitation pattern may be related to rapid conduction over the normal atrioventricular conduction system, delayed intraatrial conduction to the atrial insertion of the accessory pathway, slower conduction over the accessory pathway, or a combination of these factors. We hypothesized that a minimal preexcitation pattern generally reflects a longer intraatrial conduction time and may be of value in localizing a pathway to the left lateral region. This study examined the incidence of minimal preexcitation pattern and its potential as an electrocardiographic pathway-localizing feature in patients with WPW syndrome.

Ablation has become an important and, in some cases, the first-line therapy for a number of tachyarrhythmias. The feasibility of treating arrhythmias with ablation was initially demonstrated with surgical ablation techniques. Recently, catheter ablation techniques have replaced the surgical approach in nearly all cases. Catheter ablation is highly effective for the Wolff-Parkinson-White syndrome, atrioventricular nodal reentry, and atrial ectopic tachycardia. It is effective for atrial flutter, although approximately one quarter of patients treated with catheter ablation continue to require therapy for concomitant atrial fibrillation. The surgical maze procedure has proved to be feasible for preventing atrial fibrillation. The risks and long-term efficacy of catheter ablation maze procedures for atrial fibrillation need to be defined. The efficacy of ablation for ventricular tachycardia varies with the type of tachycardia. Catheter ablation is very effective for the rare idiopathic ventricular tachycardias that occur in structurally normal hearts and for bundle-branch reentry ventricular tachycardia, which occurs most frequently in patients with dilated cardiomyopathy. When performed at an experienced center, surgical ablation is an excellent option for selected patients with ventricular tachycardia due to prior myocardial infarction who have a discrete aneurysm but otherwise well-preserved ventricular function. Catheter ablation shows promise for this arrhythmia, but it can be offered only to those patients who have relatively slow tachycardias that allow catheter mapping. Substantial advances in mapping and ablation technology will continue to occur, allowing nonpharmacologic control of cardiac arrhythmias to be achieved in an ever greater number of patients.

Adenosine produces acute inhibition of sinus node and atrioventricular (AV) nodal function. This profound but short lived electrophysiologic effect makes adenosine a suitable agent for treating supraventricular tachycardias (SVT) that incorporate the sinus node or AV node as part of the arrhythmia circuit, or for unmasking atrial tachyarrhythmias or ventricular pre-excitation. Its antiadrenergic properties also make it an effective agent for use with some unique atrial and ventricular tachycardias. Appropriate dosing and rapid bolusing with intravenous administration is required. Recognition of infrequent proarrhythmic risks and potential drug interactions with xanthine derivatives and dipyridamole should maximize its safe and effective use. This review will highlight adenosine's mechanism of action, administration, clinical indications, efficacy, and risks when used in tachyarrhythmic management.

We analyzed 87-lead body surface QRST time-integral values (QRST values) in 29 patients with Wolff-Parkinson-White syndrome (group A, 17 patients with manifest left-sided accessory pathway; group B, 6 patients with manifest right-sided accessory pathway; and group C, 6 patients with concealed left-sided accessory pathway), before, 1 day after, and 1 week after radiofrequency catheter ablation (RCA). The number of leads with abnormal QRST values was significantly lower 1 week after RCA compared with those before RCA and 1 day after RCA in groups A and B (p < 0.05); there was no significant difference in QRST values before and 1 day after RCA in groups A and B. The QRST values over areas with preexisting repolarization abnormalities were significantly altered 1 week after RCA compared with before and 1 day after RCA in groups A and B (p < 0.01). However, there was no significant difference in the QRST values over areas without preexisting abnormalities before RCA. In group C, there were no significant differences in the QRST values or the number of leads with abnormal QRST values before, 1 day and 1 week after RCA. In conclusion, RCA did not significantly influence repolarization properties over areas without preexisting abnormalities, but gradually reduced preexisting repolarization abnormalities, which were closely related to the location of the accessory pathway in patients with manifest Wolff-Parkinson-White syndrome. Our results suggest that body surface QRST values are useful for assessment of repolarization abnormalities during the periablation period.

Transesophageal phase images and precordial electrocardiograph (ECG) were used to localize accessory pathways during adenosine-induced preexcitation in 30 patients (18 men, mean age ± SD 33 ± 14 years) undergoing endocardial mapping for suspected Wolff-Parkinson-White syndrome. Digitized 2-dimensional echocardiographic cine loops were mathematically transformed using a first harmonic Fourier algorithm before and after catheter ablation. Endocardial mapping found single accessory pathways with anterograde conduction in 20 patients, concealed pathways in 7, and atrioventricular reentry circuits in 3 patients. At baseline, precordial ECG correctly localized 8 pathways (40%) with anterograde conduction and predicted 5 adjacent locations (25%), but findings were normal in 7 patients (35%). Phase imaging correctly identified only 3 pathway locations (15%), findings were normal in 15 (75%), and could not be obtained in 2 patients (10%). Adenosine augmented manifest but minimal preexcitation in 9 patients and unmasked latent preexcitation in 7. In 4 patients, preexcitation was already maximal at baseline. During adenosine-augmented preexcitation, ECG correctly identified 13 locations (65%), but still predicted 7 adjacent locations (35%). However, phase imaging correctly identified 15 locations (75%) and predicted only 3 adjacent locations (15%). All midseptal (n = 2) and anteroseptal (n = 2) locations were correctly identified by phase imaging, but none by ECG. On follow-up studies in 16 patients, successful catheter ablation (n = 13) was equally well confirmed by ECG and phase imaging. Therefore, transesophageal echocardiographic phase imaging during adenosine-induced preexcitation is a readily available and safe procedure that appears clinically most useful for identifying septal pathways.

In summary, biplane TEE contributed significantly to successful radiofrequency catheter ablation in 6 patients with palliated single ventricle by allowing catheter positioning that may not have been possible under fluoroscopy alone, by monitoring catheter stability during application of current, and by providing immediate information regarding the presence or absence of early postablation complications.

This study showed that (1) the prevalence of MVP in patients with Wolff-Parkinson-White syndrome and AV nodal reentrant tachycardia was similar to that of the general population; (2) the location of accessory pathways was not related to the presence of MVP; and (3) MVP was persistently present after elimination of preexcitation. These findings suggest that MVP may have an independent association with PSVT. The study limitations are: (1) Acquisition bias should be noted because the prevalence of PSVT in patients found to have MVP was not obtained. (2) Comparison between patients with PSVT and an ageand sex-matched population sample in whom MVP was assessed by identical methods was not performed; thus, the association between MVP and this family of arrhythmias was not obtained. Furthermore, the higher prevalence of MVP in patients with both accessory pathway-mediated and AV nodal reentrant tachycardia must be reassessed.

Although radiofrequency catheter ablation of accessory pathways is very efficacious and the procedure is well tolerated with a relatively low risk of serious complications, some concern is warranted for ablations in the left heart. The risk of systemic embolism may be quite significant despite heparinization during the procedure and therapy with 325 mg acetylsalicylic acid orally for 3 months. The issue of anticoagulation during ablation and the method and duration of therapy after ablation requires further scrutiny.

Adult patients with the Wolff-Parkinson-White syndrome (WPW) appear to have a substrate for ventricular arrhythmia inducibility, which is higher than that of the general population.1,2 Because it is unclear whether a similar susceptibility exists in the pediatric patient with WPW. a retrospective study was performed to examine the incidence of and factors associated with ventricular arrhythmia inducibility in children.

The 12-lead electrocardiograms of 50 patients with 1 anterogradely conducting accessory pathway were analyzed to obtain characteristics of electrocardiographic findings in the midseptal, anteroseptal, true posteroseptal and right free wall accessory pathway locations. Locations were confirmed by surgery (33 patients) or radiofrequency catheter ablation (17 patients). This study analyzed (1) QRS in the frontal plane, (2) delta wave axis in the frontal plane, (3) the angle between QRS and delta wave axes, (4) the rmR S ratio in lead III, (5) negativity of delta wave in inferior leads, and (6) the rmR S ratio in precordial leads. Results were (1) QRS axis in the frontal plane in the right free wall — range from +15 to −65 ° (−32 ± 19 °); true posteroseptal pathways — range from +30 to −60 ° (−38 ± 22 °); midseptal pathways range from +15 to +60 ° (+49 ± 11 °); anteroseptal pathways range from 0 to +75 ° (+46 ± 22 °); (2) delta wave axis in the right free wall −0 to −60 ° (−32 ± 22 °); true posteroseptal − 0 to −60 ° (−43 ° 18 °); midseptal −0 to +45 ° (+24 ± 15 °), and anteroseptal −0 to +60 ° (+45 ± 17 °); (3) QRS/delta wave axis angle in the right free wall − 7 ± 6 °, true posteroseptal −9 ± 7 °; midseptal − 22 ± 6 °, and anteroseptal accessory pathways − 3 ± 5 °; (p = 0.006); (4) the rmR S ratio lead III was 1 in anteroseptal and equal to 1 in midseptal accessory pathways; (5) delta negativity in ≥2 inferior leads was observed in the right free wall −90%; in true posteroseptal −90%, in midseptal − 0%, and anteroseptal accessory pathways −0% (p rmR S ratio >1 in lead V 2 was right free wall −20%, true posteroseptal −100%, midseptal — 12%, anteroseptal −0% (p rmR S ratio in lead III. A QRS/delta wave axis angle of ≥20 ° and an rmR S ratio equal to 1 in lead III favor a midseptal accessory pathway location.