Presence Of Multiple Accessory Pathways Research Articles

Intermittent ventricular pre-excitation in symptomatic adults: Always a marker of low risk?

Intermittent ventricular pre-excitation was considered a low-risk marker for sudden death. However, to date, some studies do not exclude the existence of accessory pathways (APs) with high-risk intermittent antegrade conductive properties. According to current European Guidelines, high-risk features of APs are antegrade pathway conduction ≤250 ms in baseline or during the adrenergic stimulus, inducibility of atrioventricular reciprocating tachycardias (AVRT), inducibility of pre-excited atrial fibrillation (AF), and presence of multiple APs. For all of these transcatheter ablation is recommended. The aim of our study was to evaluate the existence of differences in risk characteristics between patients with intermittent pre-excitation (IPX) and those with persistent pre-excitation (PPX), from a sample of adults with ventricular pre-excitation and symptoms like palpitations. 293 adults [IPX: 51 (17.4%); PPX: 242 (82.6%)] underwent electrophysiological study and then catheter ablation of their APs if arrhythmia inducibility (AVRT/AF) was noted, or, conversely, if it was appreciated a fast AP antegrade conduction, in baseline or during intravenous isoproterenol infusion, or if multiple APs were detected. There were no statistically significant differences in demographic characteristics (age and gender), AVRT/AF inducibility, antegrade conductive properties, the prevalence of multiple APs, and APs locations between IPX and PPX patients. In our study, patients with IPX did not show significant differences in clinical and electrophysiological features versus PPX patients.

Symptomatic intermittent ventricular pre-excitation in adult: a monocentric retrospective study

Abstract Funding Acknowledgements Type of funding sources: None. Backgorund: Intermittent ventricular pre-excitation was considered a low-risk marker for sudden death. However, to date some studies do not exclude the existence of accessory pathways (APs) with high-risk intermittent antegrade conductive properties. High-risk features of APs are: ERP/SPERRI ≤250 msec (in basal or during adrenergic stimulus), inducibility of atrioventricular reciprocating tachycardias (AVRT), inducibility of pre-excited atrial fibrillation (AF), multiple APs. For these catheter ablation is recommended. Purpose The aim of this retrospective study was to evaluate the existence of a statistically significant difference in the risk characteristics between patients with intermittent pre-excitation (IPX) and with persistent pre-excitation (PPX), from a sample of adults with symptomatic ventricular pre-excitation (Wolff-Parkinson-White Syndrome). Methods Between August 2005 and December 2015, 293 adults (age ≥18 years) [males: 183 (62.5%)], without structural heart disease, with signs of ventricular pre-excitation and symptomatic for palpitations underwent an EP study [IPX: 51 (17.4%), males: 31 (60.8%); PPX: 242 (82.6%), males: 152 (62.8%)]. The APs were submitted to catheter ablation if EP study showed inducibility of arrhythmias (AVRT/AF) and, in case of non-inducibility of arrhythmias, if ERP ≤250 msec, in basal or during intravenous infusion of isoproterenol. Additionally, the presence of multiple accessory pathways was assessed during the test. Results The 2 groups of patients did not show statistically significant differences in age at the time of EP study [IPX: mean age 37.23±16.89 years Vs PPX: mean age 39.03±16.19 (P-value>0.05)] and gender (IPX male: 60.8% Vs PPX male: 62.8%; P-value>0.05). When measured, there were no statistically significant differences regarding ERP [IPX: mean ERP 260±45.8msec Vs PPX: mean ERP 267.7±59.6msec; P-value>0.05]. The inducibility of arrhythmias (AVRT/AF) was 59.3% in the IPX group (27 patients) vs 38% in the PPX group (92 patients), showing statistically significant differences (P-value<0.05). Multiple accessory pathways were found in 2 patients of the IPX group (3.9%), both females (100%), and in 6 patients of the PPX group (2.5%), of which 2 females (33.3%), not showing statistically significant differences (P-value>0.05). Conclusion In our study, patients with IPX did not shown statical significant differences in clinical and electrophysiological features Vs PPX partients. Thus, intermittent ventricular pre-excitation could not absolutely be considered a marker of lower arrhythmic risk.

Multiple accessory pathways coexisting with a persistent left superior vena cava: a case report

BackgroundWolff–Parkinson–White syndrome is characterized by a short PR interval (delta-wave), long QRS complex, and the appearance of paroxysmal supraventricular tachycardia. Patients with Wolff–Parkinson–White syndrome usually have one accessory pathway, whereas cases with multiple accessory pathways are rare. Persistent left superior vena cava is a vascular anomaly in which the vein drains into the right atrium through the coronary sinus at the junction of the left internal jugular and subclavian veins due to abnormal development of the left cardinal vein. The simultaneous presence of multiple accessory pathways and persistent left superior vena cava has not been reported before.Case presentationA 56-year-old Japanese man with a 5-year history of palpitations was referred for radiofrequency catheter ablation due to increased frequency of tachycardia episodes in the previous 2 months. Persistent left superior vena cava was confirmed by transthoracic echocardiography and computed tomography. An electrophysiological study revealed that the accessory pathways were located in the left lateral wall, anterolateral wall, and posteroseptal region. They were completely ablated with radiofrequency energy application.ConclusionsWe reported an extremely rare case of a patient with multiple accessory pathways and persistent left superior vena cava. Our case may suggest a potential embryological relationship between the multiple accessory pathways and persistent left superior vena cava.

Assessment of P- to delta-wave interval and its relationship with accessory pathway properties in patients with pre-excitation.

The first clinical manifestation of the Wolff-Parkinson-White syndrome in previously asymptomatic individuals may be sudden cardiac death. The options for non-invasive risk stratification are limited in the current era beyond ambulatory rhythm monitoring and an exercise stress test. In our study, we sought to investigate whether there was a relationship between the shortest measured P- to delta-wave time interval (PDI) on the conduction properties of surface electrocardiogram and accessory pathways expressed as antegrade effective refractory period (APERP). Demographic data, symptom status, electrocardiograms (ECG) and intra-cardiac recordings of invasive electrophysiology testing of 103 patients who underwent accessory pathway ablation procedures were collected. Exclusion criteria were: (1) intermittently occurring pre-excitation, which was detected in previous ECGs, (2) delta-wave resolution on treadmill test, (3) presence of multiple accessory pathways, and (4) accessory pathway locations other than the septum. The PDI was measured as the time interval from the beginning of the P wave to the earliest upstroke or downstroke of the delta wave on V1 and V2 derivations of the surface ECG, and the shortest measurement was recorded. Patients were grouped into two groups: group I, if APERP was < 240 ms and group II if APERP was ≥ 240 ms. PDI was significantly shorter in group II. By correlation analysis, a positive and moderate correlation between PDI and APERP (r = 0.598, p < 0.001) and PDI and age (r = 0.800, p < 0.001) was found, and a negative and moderate correlation between PDI and inducible AF (r = -492, p < 0.001). The best cut-off value for PDI to predict APERP ≥ 240 was 90.5 ms with a sensitivity of 80% and a specificity of 83%. Our results demonstrate that there was a strong correlation between the P- to delta-wave interval and universally accepted risk factors, such as low age, low APERP and atrial fibrillation inducibility. Further studies with larger patient groups and follow-up data are needed to appraise its predictive value.

Ablation in patients with Ebstein Anomaly and Wolff Parkinson White Syndrome

Abstract Funding Acknowledgements Type of funding sources: None. Background - Introduction: Ablation in patients with Ebstein Anomaly (EA) and Wolff Parkinson White syndrome (WPW) is challenging due to the complex anatomy and the presence of multiple accessory pathways (AP). Objectives Report the results of our recent experience of ablation in patients with EA and WPW syndrome. Methods We conducted a retrospective review of the cases of EA and WPW syndrome, which were taken to ablation in our center between 2015 and 2020. Results We found that in the indicated period 30 electrophysiological studies and ablations had been performed in 26 patients, 53.8% were males and the mean age at the time of the study was 20.6 ± 9.1 years, the mean tricuspid septal valve attachment was 44.5 ± 17.7%. Regarding the procedures, 15 were conventional studies (50%) and 15 (50%) were performed with electroanatomical mapping. We used intracardiac echocardiogram (ICE) in 10 cases (33.3%). The acute success rate was 85.7% and in the follow-up 3 patients (10%) presented recurrence. Only one patient presented a major complication, which was a complete AV block. There was a tendency to improve the acute success with the use of electroanatomical mapping in comparation with conventional studies (93.3% vs 66.6%, p = 0.068), and with the use of ICE acute success was significantly improved (100% vs 70%, p = 0.04). Seven patients presented multiple accessory pathways (26.9%). The most frequent location was the right posterolateral with 61.53%, followed by the right posteroseptal with 26.9% and the right lateral with 19.2%. Conclusions The ablation in patients with EA and WPW syndrome constitutes a challenge, we found that the use of electroanatomical mapping and the use of ICE could improve the acute success rate. New studies are needed to demonstrate the usefulness of these techniques to improve the acute success rate and to reduce the recurrence rate. ProceduresProcedures (N = 30)N%Conventional procedures1550.0Electroanatomical mapping1550.0Intracardiac echocardiogram1033.3Acute success2485.7Recurrence310.0Major complication13.3Descriptive table of our experience in ablation of patients with ED and WPW syndrome.Abstract Figure. Location of the accessory pathways

The relevance of looking for right bundle branch block in catheter ablation of Ebstein's anomaly

IntroductionEbstein's anomaly is the most commonly occurring congenital defect associated with the Wolff-Parkinson-White syndrome. In patients with Ebstein's anomaly and supraventricular tachycardia, the absence of right bundle branch block (RBBB) in sinus rhythm is a highly sensitive and specific indicator of the presence of an ipsilateral accessory AP. CaseWe present an electrophysiology case of a patient with Ebstein's anomaly and 3 ipsilateral accessory pathways. After ablation was performed, RBBB was evident. ConclusionIn patients with Ebstein's anomaly and supraventricular tachycardia, the absence of a RBBB pattern in the surface ECG after RFCA should raise suspicion for the presence of multiple accessory pathways.

Multiple accessory pathways in the young: The impact of structural heart disease

The presence of multiple accessory pathways (MultAP) is described in structural heart disease (SHD) such as Ebstein's anomaly and cardiomyopathies. Structural defects can impact the tolerability of tachyarrhythmia and can complicate both medical management and ablation. In a large cohort of pediatric patients with and without SHD undergoing invasive electrophysiology study, we examined the prevalence of MultAP and the effect of both MultAP and SHD on ablation outcomes. Accessory pathway number and location, presence of SHD, ablation success, and recurrence were analyzed in consecutive patients from our center over a 16-year period. In 1088 patients, 1228 pathways (36% retrograde only) were mapped to the right side (TV) in 18%, septum (S) in 39%, and left side (MV) in 43%. MultAP were present in 111 pts (10%), involving 250 distinct pathways. SHD tripled the risk of MultAP (26% SHD vs 8% no SHD, P < .001). Multivariable adjusted risk factors for MultAP included Ebstein's (OR 8.7[4.4-17.5], P < .001) and cardiomyopathy (OR 13.3[5.1-34.5], P < .001). Of 1306 ablation attempts, 94% were acutely successful with an 8% recurrence rate. Ablation success was affected by SHD (85% vs 95% for no SHD, P < .01) but not by MultAP (91% vs 94% for single, P = .24). Recurrence rate was higher for SHD (17% SHD vs 8% no SHD, P < .05) and MultAP (19% MultAP vs 8% single, P < .001). MultAP are found in 10% of pediatric patients, and are more common in SHD compared to those with normal hearts. Both the presence of MultAP and SHD negatively influence ablation outcomes.

Wolff-Parkinson-White Syndrome and Isoproterenol Testing in Children

Wolff-Parkinson-White syndrome (WPW) is the most common indication for invasive cardiac catheterization and electrophysiological testing in children. There are presently 2 predominant reasons for this. First, patients with WPW are, as the original 1930 investigators so eloquently pointed out, at risk for “paroxysmal tachycardia.”1 Supraventricular tachycardia is typically either orthodromic or, less commonly, antidromic reentrant tachycardia and can cause recurrent and debilitating symptoms. Present-day ablation techniques provide the promise of a cure for WPW in as many as 90% to 100% of patients who undergo this procedure with relatively low risk.2,3 Multiple studies have demonstrated the many medical, psychological, and financial benefits of ablation in the symptomatic WPW child.4–6 Article see p 73 The second reason that children with WPW undergo invasive catheterization and electrophysiological testing is to assess the risk of dying of ventricular fibrillation. The risk of sudden cardiac death in WPW in the pediatric population is, unfortunately, not known, and because of this, estimates of this risk have varied widely and range from 1% over a patient's lifetime to 0.0015 per patient-year.7,8 The reasons for not knowing this figure are myriad but ultimately stem from an inability to adequately identify both the numerator and denominator of WPW patients when creating these sorts of calculations. However, it would be fair and true to state that most authorities believe sudden cardiac death to be a rare event in both children and adults with WPW, especially in those patients who are asymptomatic. Thus, for the symptomatic child with WPW, most are in agreement that ablation, given the correct patient age, size, and history, is both appropriate and probably recommended in the majority of cases.9 However, the asymptomatic child with WPW poses significant problems for the pediatric electrophysiologist. …

Sudden Death and Ventricular Preexcitation: Is it Necessary to Treat the Asymptomatic Patients?

Currently, asymptomatic ventricular preexcitation, which has been put at rest for many decades, remains a clinical challenge as there are no predictors of sudden death, which can be the first clinical presentation of the syndrome. Identification of risk factors for sudden death is important, considering the availability of a definitive treatment. Now, as radiofrequency catheter ablation of accessory pathways has reported success rates approaching 100 percent without major complications in many centers worldwide, it becomes unacceptable that even one asymptomatic individual with WPW will die or will experience life-threatening arrhythmic events. In our extensive experience a short anterograde refractory period of accessory pathways, inducibility of sustained tachyarrhythmias and the presence of multiple accessory pathways are the strongest predictors of life-threatening arrhythmias and sudden death. Therefore, it is not yet justified that, after an incidental diagnosis of WPW syndrome has been made, no risk stratification by invasive testing is done. Subjects at high risk, particularly if young or adolescent, should be identified and then ablated in the same session as they can develop lethal arrhythmic events within a few years and this is our current practice. Recently, we sent a questionnaire to investigate clinical practices over a large number of centers around the world about asymptomatic ventricular preexcitation. A total of 100 replies were received and the results demonstrate that there is worldwide agreement in performing invasive electrophysiologic testing and prophylactic ablation in selected subjects. These findings provide strong evidence to revisit current guidelines, which appropriately in the absence of evidence had been conservative.

Radiofrequency ablation of multiple accessory pathways.

The aim of the study was to review the clinical and electrophysiological characteristics and results of radiofrequency catheter ablation in patients with multiple accessory pathways to compare them with those of patients with single accessory pathways. Electrophysiological study and radiofrequency catheter ablation were performed in 1010 consecutive cases with Wolff Parkinson White Syndrome. Presence of multiple accessory pathways was documented in 31 patients (3.1%); 30 had two, and 1 had three accessory pathways. Of the 63 accessory pathways, 42 were manifest and 21 concealed. Nine patients had Ebstein's anomaly associated with atrioventricular bypass tracts. The most common combination was right posteroseptal with right free wall bypass tracts (15 patients with 30 accessory pathways). Fifty-one of the sixty-three accessory pathways (81%) were ablated successfully without complications. The duration of the procedure was 100 +/- 58 min and the fluoroscopic time 40 +/- 17 min. A follow up of 5 +/- 3 years after ablation, demonstrated recurrences of six accessory pathways (9.5%). In conclusion, patients with multiple accessory pathways can be treated by radiofrequency ablation in only one session with a high success rate although slightly less than that in patients with a single accessory pathway (81% vs 93%, P<0.01).

Radiofrequency Current Catheter Ablation of Accessory Atrioventricular Pathways in Ebstein's Anomaly

In patients with Ebstein's anomaly, localization of accessory pathways (APs) may be impeded by abnormal local electrograms recorded along the atrialized right ventricle and by the presence of multiple APs. The impact of these factors on radiofrequency (RF) current catheter ablation of APs has not been evaluated yet. Twenty-one patients with Ebstein's anomaly and reentrant atrioventricular tachycardias underwent electrophysiological evaluation and subsequent attempts at RF catheter ablation. Thirty-four right-sided APs were found, with 30 located along the atrialized ventricle. Local electrograms in this region were normal in 10 patients but fragmented in 11. Fragmented electrograms prevented the clear distinction between atrial and ventricular activation potentials as well as the identification of AP potentials. Right coronary artery mapping was performed in 7 patients. Abolition of all 26 APs was achieved in the 10 patients with normal local electrograms and in 6 of 11 patients with abnormal electrograms. Right coronary artery mapping allowed AP localization and ablation in 5 patients. In the 5 patients with abnormal electrograms and a total of 8 APs, 6 APs could not be ablated. Unsuccessfully treated patients received antiarrhythmic drugs. During 22 +/- 12 months of follow-up, 5 patients had clinical recurrences, including 4 who had undergone a successful RF procedure. In patients with Ebstein's anomaly and reentrant atrioventricular tachycardias, factors likely to account for failure of RF catheter ablation include an AP located along the atrialized right ventricle and the abnormal morphology of endocardial activation potentials generated in this region.

Aborted sudden death in the Wolff-Parkinson-White syndrome

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.

Recurrence rate after accessory pathway ablation.

To evaluate characteristics of patients and accessory pathways as well as additional technical factors involved in the reappearance of accessory pathway conduction after successful ablation. Analysis of recurrences after radiofrequency ablation. 163 consecutive patients with 167 accessory pathways. 97 men and 66 women with a mean (SD) age of 36 (14) range (11 to 75) years. After a mean (SD) follow up of 14 (7) range (2 to 27) months, conduction recurred in 13 out of 167 (7.8%) accessory pathways. The initial manifestation of recurrence was circus movement tachycardia in 7 patients and reappearance of delta waves on a 12 lead electrocardiogram in 6 patients. The interval to the return of accessory pathway conduction ranged from 3 hours to 90 days. Age, sex, presence of multiple accessory pathways, criteria to determine the target ablation site, number and duration of radiofrequency applications, and cumulative energy did not significantly differ between the groups with recurrence and without. Recurrence was less common with concealed accessory pathways (2/44) than with overt accessory pathways (11/110). The difference was not significant. The only variable to influence the recurrences in this study group was the location of the accessory pathway. Reappearance of conduction through right sided accessory pathways occurred significantly more often than through left sided ones (8/40 v 5/114, P = 0.01). After radiofrequency ablation the recurrence rate of accessory pathways is low and there are no predictors of the risk of reappearance of conduction apart from the right sided location of the accessory pathway.

Radiofrequency ablation in multiple accessory pathways and the physiologic implications

The presence of multiple accessory pathways was noted in 24 of 210 consecutive patients (12 males and 12 females aged 15 to 77 years [mean ± SD 43 ± 16]) with the Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency ablation. Six had 3 and 18 had 2 accessory pathways. There were 25 manifest and 29 concealed accessory pathways. The location of the accessory pathways was in the left free wall in 22, the right free wall in 17, the left posterior portion of the ventricular septum in 8, the right posterior portion of the ventricular septum in 6, and the midseptum in 1. The success rate of accessory pathway ablation and the fluoroscopic time in these 24 patients with multiple accessory pathways were 89% and 78 ± 66 minutes, respectively, whereas they were 98% (p < 0.01) and 36 ± 37 minutes (p = 0.01) in the 186 patients with a single accessory pathway. The mean applications, the power level of the radiofrequency current and the application duration in these 24 patients were 21 ± 22, 30 ± 3 W, and 27 ± 10 seconds, respectively. In the 186 patients with a single accessory pathway, they were 9 ± 12 applications (p = 0.02), 30 ± 4 W (p = NS) and 26 ± 9 seconds (p = NS), respectively. Seventeen of the 24 patients had a follow-up electrophysiologic study 89 ± 40 days after ablation, and 2 (12%) had resumption of a right and left accessory pathway conduction. In conclusion, patients with multiple accessory pathways can be treated by radiofrequency ablation in a single session with a high success rate, although slightly less than that in patients with a single accessory pathway.

Ventricular fibrillation in the Wolff-Parkinson-White syndrome

Ventricular fibrillation (VF) is a well-known but rare complication of the Wolff-Parkinson-White syndrome (WPW). Clinical and electrophysiological data of 23 patients with spontaneous VF were compared with data from 100 consecutive patients with WPW without VF but with symptomatic supraventricular tachycardia. The 23 patients were collected in a multicentre retrospective study in seven European centres. VF occurred in only one patient who was receiving antiarrhythmic drugs, and was the first manifestation of the syndrome in six. No significant differences were found between those with VF and without VF in age, complaints of palpitations, syncope, and presence of structural heart disease. The retrograde effective refractory period of the accessory pathway, the atrial refractory period and the fastest atrial pacing rate with 1:1 anterograde conduction over the accessory pathway were similar in both groups. Significant differences were found for sex, permanent pre-excitation on the electrocardiogram, type of documented supraventricular tachyarrhythmias, shortest RR interval less than or equal to 220 ms during spontaneous atrial fibrillation (AF), inducibility of supraventricular tachycardias, ventricular effective refractory period less than or equal to 190 ms, mean shortest RR interval during induced AF less than or equal to 180 ms and presence of multiple accessory pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative accuracy of the vectorcardiogram and electrocardiogram in the localization of the accessory pathway in patients with Wolff-Parkinson-White syndrome: Validation of a new vectorcardiographic algorithm by intraoperative epicardial mapping and electrophysiologic studies

The scalar electrocardiograms (ECGs) and vectorcardiograms (VCGs) of 41 patients with Wolff-Parkinson-White (WPW) syndrome were used to compare the accuracy of these techniques in the identification of the site of preexcitation. The location of the accessory pathway (AP) was determined by endocavitary electrophysiologic studies in all patients and the location was confirmed during intraoperative epicardial mapping in 28 of them. The ECGs were classified according to Gallagher's criteria and with Milstein's algorithm, whereas the VCGs were classified according to a new two-step algorithm. The presence of multiple accessory pathways and coexisting myocardial infarctions were major limitations in both the VCG and ECG classification procedures. In patients with a single accessory pathway, three AP localizations (right free ventricular wall, posterior, or left free ventricular wall) were identified with the first step of the VCG algorithm, with an overall sensitivity (96.5%), specificity (90.7%), and positive predictive values (80%) that were greater than those obtained with the ECG Milstein algorithm (77.1%, 91.5%, and 75%, respectively). The second step of the VCG algorithm made it possible to identify an AP location in one of the following sites: anterior right, lateral right, posterior right, posterior left, lateral left, or anterior left ventricle. The overall sensitivity, specificity, and positive predictive values were greater for the second step of the VCG algorithm than for the ECG criteria proposed by Gallagher (43.6% versus 39.3%, 92.1% versus 87.4%, and 51.5% versus 33.3%, respectively). It was concluded that the VCG seems to be more specific and sensitive than the ECG in the identification of the preexcitation site and should be given preference in the initial evaluation of the WPW syndrome.

Importance of preexcited QRS morphology during induced atrial fibrillation to the diagnosis and localization of multiple accessory pathways.

The present investigation evaluates the ability of several electrocardiographic (ECG) and electrophysiologic methods to identify multiple accessory pathways in 47 patients in whom the presence and sites of multiple accessory pathways were confirmed intraoperatively. To establish ECG features that suggested the presence of multiple accessory pathways in these patients, we initially studied the 12-lead ECG during maximal preexcitation in 101 patients with single accessory pathways. Distinctive 12-lead ECG patterns were noted for six defined anatomic areas around the right and left atrioventricular groove. Multiple preexcited QRS morphologies, each typical for a separate accessory pathway, and atypical preexcited QRS morphologies were recorded during atrial fibrillation in 31 of 47 (66%) patients with multiple accessory pathways. By comparison, the ECG during sinus rhythm and rapid atrial pacing identified 14 (32%) and 26 (55%) of the patients, respectively. In 12 (26%) patients in whom evidence for multiple accessory pathways was absent from endocardial mapping data, atrial fibrillation provided the diagnosis. In five (11%) patients, atrial fibrillation was the only method that demonstrated the presence of multiple accessory pathways. A combination of ECG findings during atrial fibrillation and rapid atrial pacing plus endocardial mapping data identified 43 (91%) of the patients with multiple accessory pathways. There were two unique fusion patterns on the 12-lead ECG that were characteristic of specific multiple accessory pathway combinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Pre- and intraoperative identification of multiple accessory pathways. Experience of 19 pathways in 9 patients.

The pre- and intraoperative electrophysiological studies in 9 patients with two or more accessory pathways are described. The presence of multiple accessory pathways was clinically suspected in only 2 patients. During the preoperative electrophysiological study two accessory pathways were identified in 7 patients and a single pathway in 2 patients. At operation, additionally three accessory pathways were identified in 3 patients. One out of two pathways, found preoperatively, could not be confirmed in 1 patient. It is concluded that the clinical or preoperative electrophysiological evidence of only one accessory pathway should not distract one's attention from considering multiple accessory pathways in patients presenting only one type of tachycardia.