Fasciculoventricular pathways: clinical and electrophysiologic characteristics of a variant of preexcitation

Fasciculoventricular Fibers. INTRODUCTION: Fasciculoventricular tracts are considered a rare form of ventricular preexcitation. Few fasciculoventricular pathways have been reported, and none have been linked to a reentrant tachycardia. METHODS AND RESULTS: Four patients with fasciculoventricular bypass tracts underwent electrophysiologic evaluation. Two patients had a single fasciculoventricular pathway, one that inserted anteroseptally and the other in the left ventricle. Two patients also had an AV bypass tract, with anterograde conduction over the fasciculoventricular pathway during orthodromic AV reentrant tachycardia. After ablation of the AV pathways, the ECG during sinus rhythm and the electrophysiologic study showed ventricular preexcitation due to a fasciculoventricular bypass tract inserting into the right ventricle. Adenosine triphosphate was helpful in the diagnostic process. CONCLUSION: Electrophysiologists should be able to make the differential diagnosis between a fasciculoventricular bypass tract and an anteroseptal accessory pathway to preclude potential harm to the AV conduction system if a fasciculoventricular pathway is targeted for catheter ablation.     

Variants of Preexcitation—Specialized Atriofascicular Pathways, Nodofascicular Pathways, and Fasciculoventricuiar Pathways:

Variants of Preexcitation. introduction: In the present report, the electrophysiiologic findings in patients with different types of variants of preeexcitwtion, i.e., atriofascicualr, nodofacicular, and fasciculoventricular fibers, and the results of radiofrequency catheter ablation using different target sites are described. Methods and Results: Twelve patients (mean age 36 ± 17 years) with variants of the preexcitation syndromes underwent electrophysiologic study and radiofrequency catheter ablation. The atrial origin of atriofascicular pathways remote from the normal AV node was assessed by application of late atrial extrastimuli that advanced (“reset”) the timing of the next QRS complex without anterograde penetration into the AV node. In patients with atriofacicular pathways, ablation of the accessory pathway or the retrograde fast AV node pathway was attempted. Ablation of the atriofascicular pathways was guided by a stimulus-delta wave interval mapping in the first live patients and by recording of atriofascicular pathway activation potentials in the next five patients. A nodofascicular pathway was suggested if VA dissociation occurred during tachycardia and if atrial extrastimuli failed to reset the tachycardia without anterograde penetration into the AV node. A fasciculoventricular connection was suggested if the proximal insertion of the accessory pathway was found to arise from the His bundle or bundle branches. The PR interval was expected within normal limits during sinus rhythm and the QRS complex to he slightly prolonged with a discrete slurring of the R wave, suggesting a small delta wave. Ten of the 12 patients had evidence for atriofascicular pathways and one patient each for a nodofascicular and fasciculoventricular pathway. In six patients, the atriofascicular pathways were successfully ablated, and in two patients, the retrograde fast AV node pathway. In one patient, a concealed right posteroseptal accessory AV pathway served as the retrograde limb and was successfully ablated. The nodofascicular pathway was shown to he a bystander during AV node reentrant tachycardia. After successful fast AV node pathway ablation resulting in marked PR prolongation, no preexcitation was present during sinus rhythm because of the proximal insertion of the nodofascicular pathway distal to the delay producing parts of the AV node. The proximal insertion of the fasciculoventricular pathway was suggested to arise distal to the AV node at the site of the penetrating AV bundle. The earliest ventricular activation at the His-bundle recording site indicated the ventricular insertion of this accessory connection into the ventricular summit. The fasciculoventricular connection gave rise to a fixed ventricular preexcitation and served as a bystander during orthodromic AV reentrant tachycardia incorporating a left-sided accessory AV pathway.     

Electrocardiographic and electrophysiologic characteristics of anterior, midseptal and right anterior free wall accessory pathways.

OBJECTIVES. The objective of this study was to define the electrocardiographic (ECG) and electrophysiologic characteristics of midseptal, anteroseptal and right anterior free wall accessory pathways. METHODS. The fully pre-excited 12-lead surface ECGs and ECGs during orthodromic atrioventricular (AV) reentrant tachycardia were compared for 13 patients with an anteroseptal, 7 with a midseptal and 7 with a right free wall accessory pathway. Routine electrophysiologic studies were performed in all and stimulation of the right ventricular summit during tachycardia was accomplished in 10 patients. RESULTS. Differences in the surface ECGs were not sufficiently sensitive to distinguish among accessory pathway locations. Premature ventricular complexes induced from the right ventricular septal summit during ventricular activation either advanced the succeeding atrial depolarization or terminated the tachycardia in three of six patients with a septal pathway and in none of the four with a right anterior pathway. The change in ventriculoatrial (VA) interval with the development of right bundle branch block during orthodromic AV tachycardia proved most helpful in distinguishing these pathways. Patients with a right anterior free wall pathway showed a change in VA interval > or = 40 ms, whereas those with an anteroseptal pathway showed changes of 20 to 30 ms and those with a midseptal pathway showed no change. CONCLUSIONS. Anteroseptal, midseptal and right anterior free wall pathways may be distinguished by using programmed stimulation of the summit of the right ventricular septum and especially with changes in the VA interval with development of right bundle branch block during orthodromic AV reentrant tachycardia.     

Radiofrequency catheter ablation of septal accessory pathways in the pediatric age group

Radiofrequency catheter ablation (RCA) of septal accessory pathways may be technically challenging in children due to the risk of inadvertent atrioventricular (AV) block in the setting of small cardiac dimensions. Outcomes were reviewed for all patients aged < or =19 years with manifest and concealed septal accessory pathways undergoing RCA since 1990 at a single institution. One hundred forty-five procedures were performed in 127 patients (mean age 11.6 years). The number of studies according to accessory pathway location were: anteroseptal (n = 36), midseptal (n = 20), mouth of coronary sinus (n = 40), middle cardiac vein (n = 6), right posteroseptal (n = 21), and left posteroseptal (n = 22). Ablation was deferred for 9 patients (6 anteroseptal and 3 midseptal) in favor of additional pharmacologic trials. Acute success rates for targeted accessory pathways were: anteroseptal (96%), midseptal (94%), mouth of coronary sinus (88%), middle cardiac vein (100%), right posteroseptal (100%), and left posteroseptal (96%). Recurrence rates during follow-up were: anteroseptal (14%), midseptal (12%), mouth of coronary sinus (3%), right posteroseptal (4%), and left posteroseptal (4%). Permanent second or third degree AV block occurred in 4 of 136 RCA attempts (3%), involving 2 anteroseptal and 2 midseptal pathways. In 3 of these 4 cases, a high probability of block was anticipated from prior ablation efforts, prompting pacemaker insertion before or in conjunction with RCA. Thus, in the pediatric age group, acute RCA success rates for septal accessory pathways can exceed 90%. The risks of AV block and accessory pathway recurrence are most relevant to anteroseptal and midseptal pathways. These data may be factored into patient selection and the decision whether to ablate.     

Concordance of distinguishing electrocardiographic features during sinus rhythm with the location of accessory pathways in the Wolff-Parkinson-White syndrome

Knowledge of the location of accessory pathways in patients with Wolff-Parkinson-White (WPW) syndrome is pertinent to patient management. Despite the recognition that features of delta waves present during maximal preexcitation reflect ventricular activation at different sites around the anulus fibrosus, the value of electrocardiographic patterns observed during sinus rhythm, when ventricular preexcitation is often not maximal for identifying accessory pathway locations, has not been determined. In this study, 12-lead electrocardiograms recorded during sinus rhythm from 66 patients with WPW syndrome were analyzed for delta-wave polarity, QRS axis in the frontal plane, the pattern of precordial R-wave transition, and concordance between electrocardiographic patterns and the site of the accessory pathway determined using catheter and intraoperative computer mapping. Electrocardiograms from patients with left lateral sites showed negative delta waves in leads I or aVL, a normal QRS axis and early precordial R-wave transition (20 of 24 patients); left posterior sites manifested negative delta waves in II, III and aVF and a prominent R wave in V1 (14 of 16 patients); posteroseptal sites had negative delta waves in II, III and aVF, a superior QRS axis and an R less than S in V1 (all 16 patients); right free wall locations manifested negative delta waves in aVR, a normal QRS axis, and R-wave transition in V3-V5 (6 of 6 patients); and anterior septal sites had negative delta waves in V1 and V2, a normal QRS axis, and R-wave transition in V3-V5 (4 of 4 patients). Characteristic electrocardiographic patterns were not observed in 5 patients because of insufficient preexcitation. Each had a left lateral or left posterior pathway. Overall, the proposed electrocardiographic criteria derived during sinus rhythm identified correctly the accessory pathway location in 60 of 66 patients (91%). Thus, the electrocardiogram provides the physician with a reliable noninvasive means of regionalizing the location of accessory pathways in patients with WPW syndrome.     

Successful high-frequency current ablation of three accessory conduction pathways in a single session]

A case is presented of a 25-year-old symptomatic male with Wolff-Parkinson-White syndrome and three overt accessory atrioventricular connections which were all diagnosed and ablated during the same session. A discordant preexcitation pattern between delta wave and QRS axis was found on the surface electrocardiogram, indicating the presence of two or more accessory pathways. During atrial pacing the appearance of a changing QRS morphology and alternating delta wave suggested the presence of an additional left-sided pathway. After ablation of a right anteroseptal pathway, a second pathway was found located in the left lateral position and was successfully ablated. The final pathway became evident only after the ablation of the first two and was found to be located in a right midseptal position. This pathway was also ablated during this session. There were no complications and the patient remained asymptomatic during an 11-month follow-up.     

Development and Validation of an ECG Algorithm for Identifying Accessory Pathway Ablation Site in Wolff-Parkinson-White Syndrome

ECG Localization of Accessory AV Pathways. Introduction : Delta wave morphology correlates with the site of ventricular insertion of accessory AV pathways. Because lesions due to radiofrequency (RF) current are small and well defined, it may allow precise localization of accessory pathways. The purpose of this study was to use RF catheter ablation to develop an ECG algorithm to predict accessory pathway location.
Methods and Results : An algorithm was developed by correlating a resting 12-lead ECG with the successful RF ablation site in 135 consecutive patients with a single, anterogradely conducting accessory pathway (Retrospective phase). This algorithm was subsequently tested prospectively in 121 consecutive patients (Prospective phase). The ECG findings included the initial 20 msec of the delta wave in leads I, II, aVF, and V₁ [classified as positive (+), negative (-), or isoelectric (±)] and the ratio of R and S wave amplitudes in leads III and V₁ (classified as R ≥ S or R < S). When tested prospectively, the ECG algorithm accurately localized the accessory pathway to 1 of 10 sites around the tricuspid and mitral annuli or at subepicardial locations within the venous system of the heart. Overall sensitivity was 90% and specificity was 99%. The algorithm was particularly useful in correctly localizing anteroseptal (sensitivity 75%, specificity 99%), and mid-septal (sensitivity 100%, specificity 98%) accessory pathways as well as pathways requiring ablation from within ventricular venous branches or anomalies of the coronary sinus (sensitivity 100%, specificity 100%).
Conclusion : A simple ECG algorithm identifies accessory pathway ablation site in Wolff-Parkinson-White syndrome. A truly negative delta wave in lead II predicts ablation within the coronary venous system.     

Electrocardiographic and electrophysiologic characteristics of midseptal accessory pathways

BACKGROUND : The purpose of the present study was to investigate the electrocardiographic and electrophysiologic characteristics of right midseptal (RMS) and left midseptal (LMS) accessory pathways (APs), and to develop a stepwise algorithm to differentiate RMS from LMS APs. METHODS AND RESULTS: From May 1989 to February 2004, 1591 patients with AP-mediated tachyarrhythmia underwent RF catheter ablation in this institution, and 38 (2.4%) patients had MS APs. The delta wave and precordial QRS transition during sinus rhythm, retrograde P wave during orthodromic tachycardia, and electrophysiologic characteristic and catheter ablation in 30 patients with RMS APs and 8 patients with LMS APs were analyzed. There was no significant difference in electrophysiologic characteristics and catheter ablation between RMS and LMS APs. The polarity of retrograde P wave during orthodromic tachycardia also showed no statistical difference between patients with RMS and LMS APs. The delta wave polarity was positive in leads I, aVL, and V3 to V6 in patients with RMS and LMS APs. Patients with LMS APs had a higher incidence of biphasic delta wave in lead V1 than patients with RMS APs (80% vs. 15%, P=0.012). The distributions of precordial QRS transition were different between RMS APs (leads V2; n = 10, V3; n = 7 and V4; n = 3) and LMS APs (leads V1; n = 1 and V2; n = 4) (P = 0.03). The combination of a delta negative wave in lead V1 or precordial QRS transition in lead V3 or V4 had a sensitivity of 90%, specificity of 80%, positive predictive value of 95%, and negative predictive value of 66% in predicting an RMS AP. CONCLUSIONS: Delta wave polarity in lead V1 and precordial QRS transition may differentiate RMS and LMS APs.     

Accuracy and Limitations of Published Algorithms Using the Twelve-Lead Electrocardiogram to Localize Overt Atrioventricular Accessory Pathways

INTRODUCTION: The purpose of this study was to evaluate the accuracy and limitations of published algorithms using the 12-lead ECG to localize AV accessory pathways (APs). METHODS AND RESULTS: The 11 relevant algorithms found in the literature (MEDLINE database and major scientific sessions) were tested on a series of 266 consecutive patients who successfully underwent radiofrequency catheter ablation of a single overt AV AP. The positive predictive values (PPV) of the algorithms in applicable patients were significantly lower for algorithms with > 6 accessory location sites (40.6% +/- 10.9% vs 61.2% +/- 8.0%; P < 0.03) and show a tendency for algorithms not relying on delta wave polarity but on QRS polarity only (36.6% +/- 11.2% vs 52.3% +/- 13.1%; P = 0.09). The PPV in applicable patients is related to the AP location (P < 0.001) and ranked from the highest to the lowest as follows: left lateral (mean PPV = 86.3%), posteroseptal (mean PPV = 65.2%), right anteroseptal (mean PPV = 45.2%), and right posterolateral (mean PPV = 23.4%). CONCLUSION: Our study suggests that the accuracy of algorithms relying on the 12-lead ECG depends on AP locations as defined in the algorithms and on the number of AP sites. The accuracy tends to be lower when delta wave polarity is not included in the algorithm's architecture. This should be considered when using these algorithms or when building new ones.     

The electrocardiogram during sinus rhythm and tachycardia in patients with Mahaim fibers: the importance of an "rS" pattern in lead III

OBJECTIVES: The purpose of the study was to identify the electrocardiographic (ECG) characteristics of the Mahaim fiber. BACKGROUND: Mahaim fibers are slowly conducting accessory pathways reaching into the right ventricle. They often play a role in tachycardias. METHODS: We retrospectively analyzed 40 patients with Mahaim fibers. Five patients had associated Wolff-Parkinson-White syndrome and were excluded from the study. Two patients had a short atrioventricular decremental accessory pathway and were also excluded. The remaining 33 patients had a tachycardia with anterograde conduction over a Mahaim fiber. Twenty were female. Their mean age was 24 +/- 10 years. RESULTS: The most common pattern of minimal preexcitation during sinus rhythm was an rS pattern in lead III. This was found in 20 patients. There was a match between the presence of rS in lead III during sinus rhythm and left axis deviation during tachycardia with anterograde conduction over the Mahaim fiber. After ablation, a different QRS pattern emerged in lead III, indicating the absence of conduction over the Mahaim fiber. To obtain information on the prevalence of an rS pattern in lead III in age-matched controls with palpitations and without structural heart disease, the 12-lead ECG of 200 young individuals were examined. An rS pattern in lead III was found in 6%. CONCLUSIONS: A narrow QRS with an rS pattern in lead III during sinus rhythm in a patient with a history of palpitations should alert the physician to the possibility of a Mahaim fiber. During tachycardia, these patients typically show a left bundle branch block-like QRS complex with left axis deviation.     

Intermediate septal accessory pathways: electrocardiographic characteristics, electrophysiologic observations and their surgical implications

Intermediate septal accessory pathways are located in close proximity to the atrioventricular (AV) node and His bundle, have unique features that distinguish them from typical anterior and posterior accessory pathways and have been associated with a high risk for unsuccessful pathway division and the production of complete AV block after surgery. Between July 1986 and May 1990, 4 of 70 patients (3 men and 1 woman; mean age 33 +/- 13 years) undergoing surgery for accessory pathway division were found to have an intermediate septal accessory pathway. The presenting arrhythmia was atrial fibrillation with rapid anterograde conduction over the accessory pathway in two patients and recurrent orthodromic reciprocating tachycardia in two patients. In all patients, the delta wave on the electrocardiogram (ECG) was inverted in lead V1, but two patterns of delta wave configuration were observed. In three patients (type 1 intermediate septal accessory pathway), the delta wave was upright in lead II, inverted in lead III and isoelectric in lead a VF; the transition from a negative to an upright delta wave occurred in lead V2. The fourth patient exhibited a different delta wave pattern (type 2 intermediate septal accessory pathway). The delta wave was upright in each of leads II, III and aVF; the transition from a negative to an upright delta wave occurred at lead V3. Intraoperative electrophysiologic study localized the atrial insertion of type 1 pathways to the midpoint of Koch's triangle close to the AV node.(ABSTRACT TRUNCATED AT 250 WORDS)     

Supraventricular tachycardia dependent upon accessory pathways in the absence of ventricular preexcitation

Paroxysmal supraventricular tachycardia is a common disorder of cardiac rhythm, generally thought to be due to reentry within the atrioventrlcular (A-V) node. The possibility that this disorder may be a manifestation of the Wolff-Parkinson-White syndrome should always be considered, but this etiology is usually rejected if the electrocardiogram in sinus rhythm falls to demonstrate a delta wave (i.e., ventricular preexcitatlon). Several recent reports have demonstrated that an accessory A-V pathway may conduct impulses only in the retrograde or ventriculo-atrial direction. Hence, reentrant tachycardia based on a mechanism identical to that observed in patients with classic Wolff-Parkinson-White syndrome may occur, and the electrocardiogram in sinus rhythm fail to show a delta wave. This report describes 11 patients who presented with paroxysmal supraventricular tachycardia without QRS changes in sinus rhythm that suggested the Wolff-Parkinson-White syndrome. Electrophysiologic studies demonstrated that an accessory pathway participated in the mechanism of the tachycardia. Eight of these 11 patients were successfully treated by surgical interruption of either the accessory pathway or the bundle of His. Accessory pathways are not rare among patients with paroxysmal supraventricular tachycardia; and it follows that this variant of the Wolff-ParkinsonWhite syndrome is more common than would be suspected if the Wolff-Parkinson-White syndrome is considered only when delta waves are observed on the electrocardiogram.     

New algorithm for the localization of accessory atrioventricular connections using a baseline electrocardiogram

Objectives. In this study, we propose a new algorithm for accessory atrioventricalar pathway localization using a 12-lead electrocardiogram (ECG).Background. Radiofrequency catheter ablation produces a very discrete lesion, and ECG localization based en surgical dissection is obsolete.Methods. Stepwise discrimination analysis was used to assess the relation of 18 pro-excited ECG (QRS duration >100 ms) variables to the site of successful ablation in 93 patients. The most discriminating variables were combined to form rules for each location. The ECGs were retested by these rules to determine predictive accuracy.Results. If the precordlal QRS transition was at or before lead V₁, the pathway had been ablated on the left side. If it was after lead V₂, the pathway had been ablated on the right side. If the QRS transition was between leads V₁and V₂or at lead V₂, then if the R wave amplitude in lead I was greater the S wave by ≥1.0 mV, it was right-sided; otherwise, It was left-sided (p < 0.0001, sensitivity 100%, specificity 97%). Right-sided pathways. If the QRS transition was between leads V₂and V₃, the pathway was right septal; if after lead V₄, it was right lateral. If it was between leads V₃and V₄, then if the delta wave amplitude in lead II was ≥1.0 mV, it was right septal; otherwise, it was right lateral (p < 0.0001, sensitivity 97% specificity 95%). In right lateral locations, if the delta wave frontal axis was ≥0 °, or if it was <0 ° but the R wave amplitude in lead III was ≥0 mV, it was anterolateral; otherwise, it was pesterolateral (p < 0.0001, sensitivity 100%, specificity 87.3%). Anteroseptal pathways had two or more positive delta waves in leads II, III and aVF (p < 0.0001, sensitivity 100%, specificity 100%). Postereseptal pathways (two or more negative inferior lead delta waves) were less well discriminated from right midseptal pathways (inferior wave sum ≤1≥−1) (p < 0.0001, sensitivity 76.5%, specificity 71%).Leftsided pathway. Two or more positive delta waves in the inferior leads or the presence of an S wave amplitude in lead aVL greater than the R wave, or both, discriminated left anterolateral pathways from posterior pathways (p < 0.001, sensitivity and specificity 100%). If the R wave in lead I was greater than the S wave by ≥0.8 mV, and the sum of inferior delta wave polarities was negative, the location was posteroseptal; otherwise, It was posterolateral (p < 0.05, sensitivity 71.4%, specificity 100%).Conclusions. Using the algorithm derived, a right-sided accessory pathway can be reliably distinguished from one that is left-sided, right free wall from right septal, right anterolateral from posterolateral and anteroseptal from other right septal pathways. Left anterolateral pathways can be distinguished from left posterior pathways and left posterolateral pathways from left posteroseptal pathways.     

Electrocardiogram during tachycardia in patients with anterograde conduction over a Mahaim fiber: old criteria revisited.

OBJECTIVES: The aim of this study was to prospectively evaluate the sensitivity, specificity, and positive and negative predictive values of previously described ECG criteria to identify preexcited tachycardia due to decrementally conducting accessory pathways (QRS axis between 0 and -75 degrees , QRS width < or = 0.15 seconds, an R wave in lead I, an rS pattern in lead V(1), RS > 1 QRS transition > V(4), and cycle length between 220 and 450 ms). BACKGROUND: Preexcited tachycardia associated with decrementally conducting right-sided accessory pathways usually shows a rather "narrow" QRS complex and can be difficult to differentiate from supraventricular tachycardia (SVT) with left bundle branch block (LBBB) aberrant conduction. METHODS: We analyzed three groups of patients: 32 patients with an atriofascicular pathway (group I); 8 patients with long (n = 3) or short (n = 5) decrementally conducting right-sided AV pathway (group II); and a control group that consisted of 35 patients with SVT and LBBB (group III). RESULTS: Presence of all six criteria had 87.5% sensitivity in group I and a 0% sensitivity in group II. There were four false negatives in group I. The negative predictive value was 82.5%, with six false positives in group III (five patients with an aberrant LBBB-shaped tachycardia with ventriculoatrial conduction over an accessory AV pathway). The criterion cycle length was not helpful. CONCLUSIONS: Criteria for identifying a tachycardia with anterograde conduction over a Mahaim fiber are helpful only in atriofascicular pathways, with a sensitivity of 87.5% and a negative predictive value of 82.5%. The major cause of false positives was a tachycardia with aberrant LBBB conduction and ventriculoatrial conduction over an accessory AV pathway.     

Ventricular tachycardia masquerading as supraventricular tachycardia: A wolf in sheep''s clothing

It is generally assumed that if a wide QRS complex tachycardia has the same morphology on the 12-lead electrocardiogram as during sinus rhythm, the tachycardia is supraventricular. The author presents unique electrocardiographic data on four patients with QRS complex morphologies that are nearly identical during ventricular tachycardia and during sinus rhythm. The QRS complex duration during sinus rhythm was 140-180 msec and was the same as that of the tachycardia. The QRS complex morphology on the electrocardiogram was a right bundle branch block, left axis in three patients and right bundle branch block, normal axis in one patient. The mean ventricular tachycardia cycle length was 345 msec. The diagnosis of ventricular tachycardia was established by electrophysiologic testing in two patients and by atrial electrograms demonstrating AV dissociation in two patients. Thus, if the 12-lead electrocardiogram morphology of a wide QRS complex tachycardia is similar to that during sinus rhythm, it does not necessarily imply that the tachycardia is supraventricular. Ventricular tachycardia can occur with the same QRS complex morphology as occurs during sinus rhythm.     

12-Kanal-Elektrokardiogramm

The surface electrocardiogram (ECG) is an important diagnostic tool for the diagnosis of arrhythmias and acute coronary syndrome. Supraventricular tachycardias (SVT) are paroxysmal tachycardias as are sinus tachycardia, atrial tachycardia, AV nodal reentry tachycardia, and tachycardia due to accessory pathways. All SVT are characterized by a ventricular heart rate >100/min and small QRS complexes (QRS width <0.12 s) during tachycardia. It is important to analyze the relation between P wave and QRS complex to look for an electrical alternans as a leading finding for an accessory pathway. Wide QRS complex tachycardias (QRS width ≥ 0.12 s) occur in SVT with aberrant conduction and SVT with bundle branch block or ventricular tachycardia (VT). In broad complex tachycardias, AV dissociation, negative or positive concordant pattern in V₁–V₆, a notch in V₁ and QR complexes in V₆ in tachycardias with left bundle branch block morphologies are findings indicating VT. In addition, an R/S relation <1 in V₆ favors VT when right bundle branch block tachycardia morphologies are present. By analyzing the surface ECG in the right way with a systematic approach, the specificity and sensitivity of correctly identifying a SVT or VT can be raised by >95%. The 12-lead surface ECG allows the coronary culprit lesion to be located in 97% due to determination of the 12-lead ST segment deviation score.     

Electrocardiographic and electrophysiologic characteristics of anteroseptal, midseptal, and posteroseptal accessory pathways.

BACKGROUND: Approximately 30% of all accessory pathways (APs) are located in the septal area, and understanding the electrocardiographic and electrophysiologic of these APs is crucial for safe and effective ablation of these pathways. OBJECTIVE: In this study, the electrocardiographic and electrophysiologic characteristics of anteroseptal, midseptal, and posteroseptal APs were investigated in detail to elucidate unique electrical properties of APs in each location. METHODS: From April 2002 to October 2006, a total of 120 patients with a septal AP-mediated tachycardia were enrolled in the study. A detailed examination including electrocardiographic analysis and electrophysiologic study was performed in all patients. RESULTS: A total of 120 patients, including 98 patients with posteroseptal APs, 14 patients with anteroseptal APs, and 8 patients with midseptal APs, were studied. The anteroseptal APs could be differentiated from the midseptal APs by the 2 or more positive delta waves in inferior leads, whereas there is significant overlap in electrocardiographic features of midseptal and posteroseptal APs. The mean tachycardia cycle length was significantly shorter in patients with midseptal AP compared with those with anteroseptal and posteroseptal APs (284 +/- 49 ms vs 342 +/- 46 ms vs 350 +/- 68 ms, P = .03). The AH interval during tachycardia was also shorter in patients with midseptal APs (149 +/- 16 ms vs 200 +/- 51 ms vs 168 +/- 48 ms, P = .04). The patients with posteroseptal AP had a significantly higher incidence of atrial fibrillation (35%) than those with either midseptal (12%) or anteroseptal (14%) APs (P = .04). The patients with posteroseptal APs also had a significantly shorter antegrade effective refractory period of the AP (276 +/- 54 ms) than those with either midseptal (313 +/- 71 ms) or anteroseptal (325 +/- 61) APs (P = .036). CONCLUSION: Electrocardiographic analysis is a reliable method for differentiation of the anteroseptal from the midseptal APs, whereas the same is not true for the midseptal and posteroseptal APs. Midseptal APs were characterized by faster orthodromic tachycardia, whereas posteroseptal APs had a higher inducibility of atrial fibrillation.     

Catheter ablation from right atrium of anteroseptal accessory pathways using radiofrequency current.

Catheter ablation with radiofrequency current has recently been introduced as a therapeutic regimen for symptomatic patients with the Wolff-Parkinson-White syndrome or atrioventricular (AV) tachycardia mediated by a retrogradely conducting (concealed) accessory AV pathway. These pathways may be located, although infrequently, in the anteroseptal region of the heart in close proximity to the AV node-His bundle conduction system. Any attempt to interrupt an anteroseptal accessory pathway therefore is subject to the potential complication of inadvertent impairment of normal AV conduction. This study was conducted to establish whether abolition of anteroseptal accessory pathways by radiofrequency current aimed at the atrial as opposed to the ventricular insertion of the pathway can be achieved with preservation of AV node-His bundle conduction. Twelve patients (mean age 37 +/- 13 years; 10 with Wolff-Parkinson-White syndrome, 2 with a concealed accessory pathway) were studied. In the majority of patients, radiofrequency current (500 kHz; mean energy 577 +/- 207 J) was applied through a steerable catheter with a long tip electrode placed in the anterior septal space at the atrial aspect of the tricuspid anulus, with the intention to destroy the atrial insertion of the accessory pathway. All pathways were successfully ablated. The AV node or His bundle conduction was not impaired in any patient. Right bundle branch block was induced in two patients (17%). There were no complications related to the procedure. It is concluded that catheter ablation from the right atrium using radiofrequency current provides effective and safe interruption of anteroseptal accessory pathways with good preservation of the normal conduction system.     

Coexistent posteroseptal and right-sided atrioventricular bypass tracts

Twelve patients with a posteroseptal accessory pathway underwent complete electrophysiologic studies, and four were found to have a second atrioventricular (AV) bypass tract that was right anterior, right anteromedial or right anterolateral in location. In two of these four patients, the presence of the right-sided AV bypass tract was confirmed by intraoperative epicardial mapping or after catheter-induced abolition of retrograde conduction through the posteroseptal bypass tract. In three of the four patients with a dual AV bypass tract, the delta wave pattern was clearly atypical of the pattern seen with an isolated posteroseptal accessory pathway. Instead of a transition from an isoelectric or slightly positive delta wave in lead V1 to markedly positive delta waves in leads V2 to V6, the delta waves were negative or only slightly positive in leads V2 to V5. However, in a fourth patient with dual AV bypass tracts, the only atypical electrocardiographic finding was an intermittently positive delta wave in lead II; at times this patient's electrocardiogram was consistent with an isolated posteroseptal bypass tract, with negative delta waves in the inferior leads. There appears to be an association between posteroseptal and right-sided accessory pathways. In patients with a posteroseptal accessory pathway who are candidates for catheter or surgical bypass tract ablation, a complete mapping study of the tricuspid anulus is mandatory, even when the electrocardiogram is typical of an isolated posteroseptal bypass tract.     

Paroxysmal supraventricular tachycardia caused by 1: 2 atrioventricular conduction in the presence of dual atrioventricular nodal pathways

One-to-two atrioventricular conduction, ie, the double response to a single sinus or atrial impulse, resulting in two QRS complexes for one P wave, is a rare manifestation of dual atrioventricular (AV) nodal pathways. This report describes the case of a 61-year-old woman with continuous episodes of supraventricular tachycardia caused by independent conduction to the ventricles of sinus impulses over both the fast and the slow AV nodal pathway, giving rise to a ventricular rate that was twice the sinus rate. A wide spectrum of electrocardiographic manifestations of 1:2 AV conduction was observed on the surface electrocardiogram. The diagnosis was suggested by several elements including evidence of dual AV nodal pathways during sinus rhythm and cycle length alternans during tachycardia. The patient underwent successful slow pathway ablation with complete disappearance of symptoms and electrocardiographic manifestations of 1:2 AV conduction.