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Aim: In cardiac arrest, ventricular fibrillation (VF) waveform analysis has identified the amplitude spectrum area (AMSA) as a key predictor of defibrillation success and favorable neurologic survival. New resuscitation protocols are under investigation, where prompt defibrillation is restricted to cases with a high AMSA. Appreciating the variability of in-field pad placement, we aimed to assess the impact of recording direction on AMSA-values, and the inherent defibrillation advice. Methods: Prospective VF-waveform study on 12-lead surface electrocardiograms (ECGs) obtained during defibrillation testing in ICD-recipients (2010–2017). AMSA-values (mVHz) of simultaneous VF-recordings were calculated and compared between all limb leads, with lead II as reference (proxy for in-field pad position). AMSA-differences between leads I and II were quantified using Bland-Altman analysis. Moreover, we investigated differences between these adjacent leads regarding classification into high (≥15.5), intermediate (6.5–15.5) or low (≤6.5) AMSA-values. Results: In this cohort (n = 243), AMSA-values in lead II (10.2 ± 4.8) differed significantly from the other limb leads (I: 8.0 ± 3.4; III: 12.9 ± 5.6, both p < 0.001). The AMSA-value in lead I was, on average, 2.24 ± 4.3 lower than in lead II. Of the subjects with high AMSA-values in lead II, only 15% were classified as high if based on assessments of lead I. For intermediate and low AMSA-values, concordances were 66% and 72% respectively. Conclusions: ECG-recording direction markedly affects the result of VF-waveform analysis, with 20–30% lower AMSA-values in lead I than in lead II. Our data suggest that electrode positioning may significantly impact shock guidance by ‘smart defibrillators’, especially affecting the advice for prompt defibrillation.

Background In cardiac arrest, computerized analysis of the ventricular fibrillation (VF) waveform provides prognostic information, while its diagnostic potential is subject of study. Animal studies suggest that VF morphology is affected by prior myocardial infarction (MI), and even more by acute MI. This experimental in‐human study reports on the discriminative value of VF waveform analysis to identify a prior MI. Outcomes may provide support for in‐field studies on acute MI. Methods and Results We conducted a prospective registry of implantable cardioverter defibrillator recipients with defibrillation testing (2010–2014). From 12‐lead surface ECG VF recordings, we calculated 10 VF waveform characteristics. First, we studied detection of prior MI with lead II, using one key VF characteristic (amplitude spectrum area [AMSA]). Subsequently, we constructed diagnostic machine learning models: model A, lead II, all VF characteristics; model B, 12‐lead, AMSA only; and model C, 12‐lead, all VF characteristics. Prior MI was present in 58% (119/206) of patients. The approach using the AMSA of lead II demonstrated a C‐statistic of 0.61 (95% CI, 0.54–0.68). Model A performance was not significantly better: 0.66 (95% CI, 0.59–0.73), P =0.09 versus AMSA lead II. Model B yielded a higher C‐statistic: 0.75 (95% CI, 0.68–0.81), P P =0.66 versus model B. Conclusions This proof‐of‐concept study provides the first in‐human evidence that MI detection seems feasible using VF waveform analysis. Information from multiple ECG leads rather than from multiple VF characteristics may improve diagnostic accuracy. These results require additional experimental studies and may serve as pilot data for in‐field smart defibrillator studies, to try and identify acute MI in the earliest stages of cardiac arrest.

Updates of resuscitation guidelines have limited high-level supporting evidence. Moreover, the overall effect of such bundled practice changes depends not only on the impact of the individual interventions but also on their interplay and swift functioning of the entire chain of survival. Therefore, real-world data monitoring is essential. We performed a meta-analysis of comparative studies on outcomes before and after successive guideline updates. On January 16, 2019, we searched for comparative studies (PubMed, Web-of-Science, Embase, and the Cochrane Libraries) reporting outcomes before and after resuscitation guidelines 2005, 2010, and 2015. We followed PRISMA, Cochrane, and Moose-recommendations. Studies on outcomes during the 2005 versus 2000 guideline period (n = 23; 40,859 patients) reported significantly higher ROSC (odds ratio [OR] 1.21 [1.04 to 1.42], p = 0.014), survival to admission (OR 1.34 [1.09 to 1.65], p = 0.005), survival to discharge (OR 1.46 [1.25 to 1.70], p0.001), and favorable neurologic outcome (OR 1.35 [1.01 to 1.81], p = 0.040). Studies on outcomes during the 2010 versus 2005 guideline period (n = 11; 1,048,112 patients) indicated no difference in ROSC (OR 1.25 [95% confidence interval 0.95 to 1.63], p = 0.11), whereas survival to discharge improved significantly (OR 1.30 [1.17 to 1.45], p0.001). Only 2 studies reported on neurologic outcomes, both showing improved outcome after the 2010 guideline update. No data on the 2015 guidelines were available. This meta-analysis on real-world data of1 million patients demonstrates improved outcomes after the 2005 and 2010 resuscitation guideline updates, and a lack of data on the 2015 guideline. In conclusion, although limited in terms of causality, this study suggests that the sum of all efforts to improve outcomes, including updated CPR guidelines, contributed to increased survival after cardiac arrest.

Introduction In view of the shift from routine toward no or selective defibrillation testing, optimization of the current risk stratification for inadequate defibrillation safety margins (DSMs) could improve individualized testing decisions. Given the pathophysiological differences in myocardial substrate between ischemic and nonischemic heart disease (IHD/non-IHD) and the accompanying differences in clinical characteristics, we studied inadequate DSMs and their predictors in relation to the underlying etiology. Methods and results Cohort of routine defibrillation tests (n = 785) after first implantable cardioverter defibrillator (ICD)-implantations at the Radboud UMC (2005-2014). A defibrillation threshold >25 J was regarded as an inadequate DSM. In total, 4.3% of patients had an inadequate DSM; in IHD 2.5% versus 7.3% in non-IHD (P = 0.002). We identified a group of non-IHD patients at high risk (13-42% inadequate DSM); the remainder of the cohort (>70%) had a risk of only 2% (C-statistic entire cohort 0.74; C-statistic non-IHD 0.82). This was based upon two identified interaction terms: (1) non-IHD and age (aOR 0.94 [95% CI 0.91-0.97]); (2) non-IHD and the indexed left ventricular (LV) internal diastolic diameter (aOR 3.50 [95% CI 2.10-5.82]). Conclusion The present study on risk stratification for an inadequate DSM not only confirms the importance of making a distinction between IHD and non-IHD, but also shows that risk factors in an entire cohort (LV dilatation, age) may only apply to a subgroup (non-IHD). Appreciation of this concept could favorably affect current risk stratification. If confirmed, our approach may be used to optimize individualized testing decisions in an upcoming era of non-routine testing.

Contains fulltext : 182938.pdf (Publisher’s version ) (Open Access) BACKGROUND: Despite a promising association between VF waveform characteristics and prognosis after resuscitation, studies with VF-guided treatment have so far not improved outcomes. While driven by the idea that the VF waveform reflects arrest duration, increasing evidence suggests that pre-existent disease-related changes of the myocardium affect ECG-characteristics of VF as well. In this context, we studied the impact of the left ventricular (LV) diameter and mass. METHODS: Cohort of 193 ICD-patients with defibrillation testing at the Radboudumc (2010-2014). Surface ECG-recordings (leads I,II,aVF,V1,V3,V6) were analysed to study amplitude and frequency characteristics of the induced VF. Both for LV diameter and mass, patients were categorised in two groups, using echocardiographic data (ASE-guidelines). RESULTS: In all ECG-leads, dominant and median frequencies were significantly lower in patients with (n=40) than in patients without (n=151) an increased LV diameter. The mean amplitude and amplitude spectrum area (AMSA) did not differ. In contrast, we observed no differences in frequency characteristics in relation to the LV mass, whereas mean amplitude (I,aVF,V3) and AMSA (I,V3) were significantly higher in patients with (n=57) than in patients without (n=120) an increased LV mass. CONCLUSIONS: Frequency characteristics of VF were consistently lower in case of an increased LV diameter. Whereas LV mass does not affect the frequency of the VF waveform, amplitudes seem higher with increasing mass. These findings add to the current knowledge of factors that modulate VF characteristics of the surface ECG and provide insight into factors which may be accounted for in future studies on VF-guided resuscitative interventions.

Background Ventricular fibrillation (VF) waveform characteristics are associated with cardiac arrest duration and defibrillation success. Recent animal studies found that VF characteristics and shock success also depend on the presence of myocardial infarction (MI). In patients, VF induction after implantable cardioverter defibrillator (ICD) implantation offers a unique setting to study early VF characteristics: we studied the relation with cardiac disease – either presence or absence of a previous MI – and with shock success. Methods Retrospective cohort study of ICD-patients who underwent defibrillation testing, 117 (63%) with and 69 (37%) without a previous MI. Intracardiac recordings of induced VF were analysed using Fourier analysis. Results In previous MI-patients, the fundamental frequency and organisation index of the VF signal were significantly lower as compared with patients without a previous MI: 4.9Hz±0.6 vs. 5.2Hz±0.6 ( p =0.005) and 56%±10 vs. 60%±9 ( p =0.001), respectively. The median frequency was not different ( p =0.25). We found no association between VF characteristics and ICD shock success. Conclusions In analogy with observations in animals, we found that a history of a previous MI was associated with slower and less organised VF. In our cohort of ICD-patients, early VF waveform characteristics were not associated with shock outcomes. Further study is warranted to determine to what extent VF characteristics are influenced by the underlying aetiology on the one hand, and time delay on the other. These findings could improve insight into the potential value of VF analysis to guide shock delivery.

Contains fulltext : 59318.pdf (Publisher’s version ) (Closed access) OBJECTIVES: The purpose of this study was to characterize the morphology of fibrillation electrograms in patients in order to provide insight into the underlying electropathologic substrate of atrial fibrillation (AF). BACKGROUND: Electrograms recorded during AF show a high degree of spatiotemporal variation. METHODS: AF was induced by rapid atrial pacing in 25 patients undergoing cardiac surgery. A unipolar mapping array of 244 electrodes was positioned on the free wall of the right atrium to record multiple epicardial fibrillation electrograms. Local anisotropy in conduction and epicardial wavefront curvature during AF were determined by fitting the best quadratic surface on the activation times of rectangular areas of 3 x 3 electrodes. RESULTS: During AF, unipolar epicardial electrograms revealed a clear predominance of S waves. The average RS difference during type I and II AF was -0.15 +/- 0.08 and -0.22 +/- 0.08. During type III AF, the predominance of S waves was less prominent (-0.07 +/- 0.05; P < .005). In all types of AF, the degree of anisotropy in conduction was remarkably low (anisotropy ratio: 1.24 +/- 0.09), and no clear directional effect on the relative amplitude of R and S waves was found. There was a weak relationship between local curvature of wavefronts and RS difference (r = 0.23; P < .01). Computer simulations showed that the negative RS difference could result from transmural activation in an epicardial to endocardial direction. CONCLUSIONS: The clear predominance of S waves in epicardial fibrillation electrograms is not due to anisotropy and can only be partly explained by a high curvature of fibrillation waves. Predominant epicardial to endocardial activation seems to be important in producing rS electrograms on the epicardium. This finding provides indirect evidence that the thin epicardial layer of atrial myocardium plays an important role in propagation of fibrillation waves.

Background In this feasibility study, early results are presented of our first series of patients with microwave ablation for atrial fibrillation (AF) on the beating heart. Methods From June 2001 until December 2001, a total of 24 patients underwent beating-heart epicardial ablation for AF. With a microwave antenna, the left and right pulmonary veins were isolated and connected to each other followed by amputation of the left atrial appendage. Subsequently, patients underwent either off-pump coronary artery bypass graft or valve surgery on pump. The mean age of the patients was 67.4 ± 6 years. Three patients experienced paroxysmal atrial fibrillation and all others chronic AF. Mean left atrial diameter was 5.4 ± 0.6 cm, and mean ablation time was 13 min. Results All procedures but one were completed successfully on the beating heart. All patients were in sinus rhythm after the procedure. A total of 15 patients experienced periods with postoperative AF during hospital stay; 9 of these patients were discharged with AF. All patients received either sotalol or amiodarone. At latest follow-up (3 to 9 months), 20 of 23 patients were in sinus rhythm. Conclusions With microwave ablation, electrical isolation of the pulmonary veins can be achieved epicardially without cardiopulmonary bypass support.

A catheter-based method of mapping left ventricular electromechanical regional function may be used to optimize application of local myocardial therapies by demarcating zones of ischemia or infarction. We thus performed a detailed comparison between electromechanical parameters and segmental function as assessed by echocardiography in 10 patients (3 with normal ventricles and 7 with old infarcts). Using a 16-segment model, unipolar voltage and local shortening were significantly and independently related to echo score by multivariate analysis, having a concordance with echo score of 73% for shortening and 79% for voltage. Area under ROC curves, expressing the ability to differentiate normal from abnormal segments, had values of 0.75 and 0.81 for local shortening and unipolar voltage, respectively. In conclusion, automatic assessment of regional ventricular function can be achieved independently by electrical and mechanical parameters, compared with echocardiography, permitting an integrated approach to the evaluation of ventricular function and aiding localization of catheter-based therapies.

Background —Accurate mapping of the site of origin and activation sequence of a cardiac arrhythmia is essential for a successful catheter ablation procedure. To achieve this, precise and reproducible catheter manipulation is mandatory. The aim of this study was (1) to assess the accuracy of a new nonfluoroscopic mapping system in humans and (2) to report the first result of endocardial activation mapping with this system during sinus rhythm and several types of supraventricular and ventricular tachycardias. Methods and Results —Fifteen patients were studied. Accuracy measurements were performed in 5 of them (patients 5, 6, 7, 8, and 14). The distances between two subsequent catheter positions in the inferior caval vein as determined by the nonfluoroscopic mapping system were compared with measurements made with calipers by four independent investigators using identification marks on the catheter shaft. The difference between these two methods was 0.95±0.8 mm. In 15 patients, activation of the right atrium and/or the right or left ventricle was recorded during sinus rhythm. Three-dimensional activation maps were constructed in patients with atrial and ventricular tachycardias and Wolff-Parkinson-White syndrome. Conclusions —With this new nonfluoroscopic mapping technique, accurate positioning of the catheter tip is possible. A three-dimensional activation map can be reconstructed during sinus rhythm and during supraventricular and ventricular tachycardias of different compartments of the heart.

Electrode Length for Atrial Defibrillation. Introduction: Catheter-based electrodes have been used previously to terminate episodes of atrial fibrillation in animals and man. Typically, these electrodes span 6 to 7 cm, and lowest energy requirements are achieved when these electrodes are positioned in the distal coronary sinus and in the right atrium. The purpose of this study was to evaluate the use of longer electrode lengths for atrial defibrillation. Methods and Results: In 15 patients, two decapolar catheters were inserted, one into the distal coronary sinus and one in the right atrium. To provide longer electrodes lengths, a third catheter was inserted and alternated positioned in the right atrium or coronary sinus. A 6-cm electrode span was obtained by using the distal 8 rings on the coronary sinus catheter or 8 consecutive electrodes on the right atrial catheter and increased from 6 to 11 cm by connecting consecutive, nonoverlapping rings of the third catheter with the 10 rings of the initial right atrial or coronary sinus catheter. Atrial defibrillation thresholds were determined twice, in a randomized order, in each patient for each of the three combinations of electrode lengths. All 15 patients could he successfully converted to sinus rhythm without complications; however, one patient could be converted reproducibly with only 2 of the 3 electrode combinations. Mean thresholds were 306 ± 102 V, 5.9 ± 4.0 J for the 6 cm/6 cm electrode length combination with an impedance of 72 ± 18 ω. For the electrode combination using the 11-cm electrode in the right atrium, the defibrillation threshold was 296 ± 107 V, 5.8 ± 3.9 J with an impedance of 61 ± 17 ω and was 294 ± 91 V, 5.6 ± 3.6 J with an impedance of 55 ± 11 ω for the 11-cm electrode in the coronary sinus. There were no significant differences in defibrillation voltage or energy (P > 0.05) associated with the longer electrode lengths; however, the longer electrode lengths did significantly lower shock impedance (P < 0.05). Conclusion: The use of longer electrodes, when using the right atrium to coronary sinus shock vector, does not lower the defibrillation requirements for restoration of sinus rhythm.

Sudden death can be the first manifestation of the Wolff-Parkinson-White (WPW) syndrome. The underlying mechanism being atrial fibrillation with a very high ventricular rate, because of a short anterograde refractory period of the accessory atrioventricular pathway (AP), deteriorating into ventricular fibrillation. Information on the anterograde refractory period of the AP is therefore important to recognize asymptomatic people with the WPW ECG at risk for dying suddenly. Several noninvasive tests are available to identify the low risk patient. Decision making when to interrupt the AP in asymptomatic WPW patients not at low risk requires an invasive study to document the electrophysiological properties of the AP and to determine its exact location.

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

Monomorphic VT in HCM. Introduction: Incessant monomorphic ventricular tachycardia (VT) with a right bundle branch block morphology and a northwest axis is a rare arrhythmic complication in a patient with hypertrophic cardiomyopathy and apical left ventricular aneurysm. Methods and Results: The origin of this VT was localized using the following criteria: the presence of entrainment without fusion, equal internals from the stimulus to the beginning of the QRS complex and from the electrogram to the QRS complex during VT, and the first postpacing interval identical to the tachycardia cycle length. Radiofrequency energy applied to the septoapical part of the apical left ventricular aneurysm terminated the tachycardia within 2 seconds. Conclusion: Using criteria to guide radiofrequency (RF) ablation of VT in patients with coronary artery disease, an incessant monomorphic VT in a patient with hypertrophic cardiomyopathy was successfully ablated.

Background During atrial fibrillation (AF), the atrium is activated by multiple wavelets that continuously change in size and direction. The aim of this study was to correlate the temporal variation in AF electrogram configuration with the varying spatial patterns of activation. Methods and Results In a group of 25 Wolff-Parkinson-White patients undergoing cardiac surgery, the free wall of the right atrium was mapped (244 points) during electrically induced AF. The unipolar electrograms recorded during 4 seconds of AF were classified into four categories: (1) single deflections, (2) short-double potentials, (3) long-double potentials, and (4) fragmented potentials. The proportion of these four types of electrograms during AF was as follows: singles, 77±12%; short-doubles, 7±3%; long-doubles, 10±7%; and fragmented, 6±4%. Electrogram morphology was an indicator for rapid uniform conduction (single potentials; positive predictive value [PPV] of 0.96), collision (short-double potentials; PPV of 0.33), conduction block (long-double potentials; PPV of 0.84), and pivoting points or slow conduction (fragmented potentials; PPV of 0.87). In type I, II, and III AF, the proportion of long-double potentials was 4±2%, 12±3%, and 18±7% ( P P Conclusions The morphology of single unipolar electrograms during AF reflects the occurrence of various specific patterns of conduction. This might be used to differentiate between different types of AF and to identify regions with structural conduction disturbances involved in perpetuation of chronic AF.

Contains fulltext : 125460.pdf (Publisher’s version ) (Open Access) PURPOSE: This study was conducted to investigate the degree of fibrosis in atrial appendages of patients with and without atrial fibrillation (AF) undergoing cardiac surgery. In addition, we hypothesized that areas of atrial fibrosis can be identified by electrogram fractionation and low voltage for potential ablation therapy. METHODS: Interstitial fibrosis from right (RAA) and/or left atrial appendages (LAA) was studied in patients with sinus rhythm (SR, n = 8), paroxysmal (n = 21), and persistent AF (n = 20) undergoing coronary artery bypass and/or aortic or mitral valve surgery. Atrial fibrosis quantification was performed with Masson trichrome staining. Intraoperative bipolar epicardial electrophysiological measurements were performed to correlate fibrosis to electrogram fractionation, voltage, and AF cycle length. RESULTS: The average degree of fibrosis was 11.2 +/- 7.2 % in the LAA and 22.8 +/- 7.6 % in the RAA (p < 0.001). Fibrosis was not significantly higher in paroxysmal AF patients compared to SR subjects (18.2 +/- 8.7 versus 20.7 +/- 5.3 %). Persistent AF patients had a higher degree of LAA and RAA fibrosis compared to paroxysmal AF patients (LAA 14.6 +/- 8.7 versus 8.6 +/- 4.7 %, p = 0.02, and RAA 28.2 +/- 7.9 versus 18.2 +/- 8.7 %, respectively, p = 0.04). The left atrial end diastolic volume index was higher in persistent AF patients compared to SR controls (38.3 +/- 16.4 and 28 +/- 11 ml/m(2), respectively, p = 0.04). No correlation between atrial fibrosis and electrogram fractionation or voltage was found. CONCLUSION: Patients with structural heart disease undergoing cardiac surgery have more fibrosis in the RAA than in the LAA. Furthermore, RAA fibrosis is increased in persistent AF but not paroxysmal AF patients compared to control subjects. Electrogram fractionation and low voltage did not provide accurate identification of the fibrotic substrate.

OBJECTIVE--To examine the value of programmed electrical stimulation of the heart in predicting sudden death in patients receiving amiodarone to treat ventricular tachyarrhythmias after myocardial infarction. DESIGN--Consecutive patients; retrospective study. SETTING--Referral centre for cardiology, academic hospital. PATIENTS--106 patients with ventricular tachycardia (n = 77) or ventricular fibrillation (n = 29) late after myocardial infarction. INTERVENTIONS--Programmed electrical stimulation was performed while on amiodarone treatment for at least one month. MEASUREMENTS AND MAIN RESULTS--In 80/106 patients either ventricular fibrillation (n = 15) or sustained monomorphic ventricular tachycardia (n = 65) was induced. After a mean follow up of 50 (SD 40) months (1-144), 11 patients died suddenly and two used their implantable cardioverter debfibrillator. By multivariate analysis two predictors for sudden death were found: (1) inducibility of ventricular fibrillation under amiodarone treatment (P << 0.001), and (2) a left ventricular ejection fraction of < 40% (P < 0.05). The survival rate at one, two, three, and five years was 70%, 62%, 62%, and 40% respectively for patients in whom ventricular fibrillation was induced, and 98%, 96%, 94%, 94% for patients with induced sustained monomorphic ventricular tachycardia. Where there was no sustained arrhythmia, five year survival was 100%. CONCLUSIONS--In patients receiving amiodarone because of life threatening ventricular arrhythmias after myocardial infarction, inducibility of ventricular fibrillation, but not of sustained monomorphic ventricular tachycardia, indicates a high risk of sudden death.

Item does not contain fulltext AIMS: Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Nowadays, catheter-based ablative approaches are mainly reserved for drug-refractory patients. However, the value of an ablative therapy as a first-line alternative remains elusive. The aim of our study was to analyse the acute procedural success and clinical outcome of patients with lone paroxysmal AF undergoing cryoballoon ablation (CBA) as first-line treatment. METHODS AND RESULTS: Eighteen individuals (mean age 44 +/- 9 years, range 23-61 years, 15 males) with lone paroxysmal AF preferring a catheter-based treatment to drug treatment as first-line therapy were consecutively enrolled in our study. Mean left atrial size was 39 +/- 4 mm and mean left ventricular ejection fraction 58 +/- 3%. After a mean of 2.4 CBA (range 2-4) applications pulmonary vein (PV) isolation could be demonstrated in 70 (97%) PVs. Additional lesions with a focal ablation catheter were needed to isolate one right inferior pulmonary vein and one left superior pulmonary vein in two different patients. At the end of the procedure, all (100%) PVs were isolated. After a 2-month blanking period, 16 patients (89%) were free of symptomatic AF recurrence at a mean follow-up of 14 +/- 9 months and without antiarrhythmic drugs (AADs). CONCLUSION: Cryoballoon ablation in patients with lone paroxysmal AF yields a high acute efficacy rate with a great chance of being free of symptomatic AF recurrence without antiarrhythmic drugs on a mid-term follow-up period, when offered as a first-line treatment. 01 februari 2012

The acute anatomic and valvular consequences of radiofrequency catheter ablation of accessory pathways were evaluated in 62 patients by means of serial echocardiographic examinations. Semiquantitative assessment of valvular incompetence and classification into one of four grades according to the width and the extension of the jet from the valvular orifice were carried out. Segmental wall motion abnormalities were evaluated semiquantitatively with four grades of severity (normal, hypokinesia, akinesia, or dyskinesia). New echocardiographic abnormalities were observed in five patients. One thrombus on the ventricular aspect of the mitral valve, three hemodynamically insignificant pericardial effusions, and one increase in severity of tricuspid incompetence were found 1 day after radiofrequency catheter ablation. We conclude that echocardiographic changes after radiofrequency ablation of accessory pathways are rare and of minor significance. These findings confirm the safety of the procedure.

A 78-year-old man presents with dizziness for 3 days. This lasts for 30 s to 1 min; he does not feel palpitations and has no other cardiac symptoms. Nine years ago, he was analysed for chest pain; exercise testing and echocardiography were normal. His further medical history reveals depression and hemi-colectomy because of colon carcinoma. Current medication consists of aspirin, lisinopril, simvastatin, lithium carbonate, nortrilen, pantozol, alprazolam and movicolon. Physical examination revealed a slow regular pulse of 40 beats/min with a blood pressure of 110/60 mmHg, and investigation of heart and lungs was within normal limits. The ECG on admission is shown in Fig. 1. Laboratory examination showed a normal blood level of lithium and nortrilen. The echocardiography showed normal left ventricular function with a mild aortic stenosis. Fig. 1 ECG on admission (25 mm/s, 10 mm/mV) What is your interpretation of the ECG? ■ Answer You will find the answer elsewhere in this issue.

We studied the relationship between wall motion abnormalities determined by echocardiography and the signal-averaged electrocardiogram in 82 consecutive patients during the acute phase of a first myocardial infarction. An abnormal signal-averaged electrocardiogram was defined as the presence of two of the following criteria: a QRS durationor = 114 ms, a root mean square voltage (RMS) of the last 40 msor = 25 microV and an amplitude signal lower than 40 microV lastingor = 39 ms. The left ventricle was divided into 13 segments and the contraction pattern divided into akinesia alone (including dyskinesia) (group A), hypokinesia alone (group B) and both hypokinesia and akinesia (group C). An abnormal signal-averaged electrocardiogram was found in 14/82 patients (17%) and was correlated with the persistence of occlusion of the infarct-related vessel (32% vs 9%, P0.02). In patients with a patent vessel, the incidence of an abnormal signal-averaged electrocardiogram was 14% in group A, 9% in group B and 0% in group C (NS). In patients with an occluded vessel an abnormal signal-averaged electrocardiogram was found in 10% of group A patients, in 36% in group B patients and in 75% of group C patients (P = 0.05). Our study suggests that the presence of hypokinetic areas during the acute phase of a first myocardial infarction and an abnormal signal-averaged electrocardiogram indicate an occluded infarct-related vessel.

Background— During persistent atrial fibrillation (AF), waves with a focal spread of activation are frequently observed. The origin of these waves and their relevance for the persistence of AF are unknown. Methods and Results— In 24 patients with longstanding persistent AF and structural heart disease, high-density mapping of the right and left atria was performed during cardiac surgery. In a reference group of 25 patients, AF was induced by rapid pacing. For data analysis, a mapping algorithm was developed that separated the fibrillatory process into its individual wavelets and identified waves with a focal origin. During persistent AF, the incidence of focal fibrillation waves in the right atrium was almost 4-fold higher than during acute AF (median, 0.46 versus 0.12 per cycle per 1 cm 2 (25th to 75th percentile, 0.40 to 0.77 and 0.01 to 0.27; P 3) happened in only 0.8. The coupling interval was not more than 11 ms shorter than the average AF cycle length ( P =0.04), and they were not preceded by a long interval. Unipolar electrograms at the site of origin showed small but clear R waves. These data favor epicardial breakthrough rather than a cellular focal mechanism as the underlying mechanism. Often, conduction from a site of epicardial breakthrough was blocked in 1 or more directions. This generated separate multiple wave fronts propagating in different directions over the epicardium. Conclusions— Focal fibrillation waves are due to epicardial breakthrough of waves propagating in deeper layers of the atrial wall. In patients with longstanding AF, the frequency of epicardial breakthroughs was 4 times higher than during acute AF. Because they provide a constant source of independent fibrillation waves originating over the entire epicardial surface, they offer an adequate explanation for the high persistence of AF in patients with structural heart disease.

Background— The electropathological substrate of persistent atrial fibrillation (AF) in humans is largely unknown. The aim of this study was to compare the spatiotemporal characteristics of the fibrillatory process in patients with normal sinus rhythm and long-standing persistent AF. Methods and Results— During cardiac surgery, epicardial mapping (244 electrodes) of the right atrium (RA), the left lateral wall (LA), and the posterior left atrium (PV) was performed in 24 patients with long-standing persistent AF. Twenty-five patients with normal sinus rhythm, in whom AF was induced by rapid pacing, served as a reference group. A mapping algorithm was developed that separated the complex fibrillation process into its individual elements (wave mapping). Parameters used to characterize the substrate of AF were (1) the total length of interwave conduction block, (2) the number of fibrillation waves, and (3) the ratio of block to collision of fibrillation waves (dissociation index). In 4403 maps of persistent AF, no evidence for the presence of stable foci or rotors was found. Instead, many narrow wavelets propagated simultaneously through the atrial wall. The lateral boundaries of these waves were formed by lines of interwave conduction block, predominantly oriented parallel to the atrial musculature. Lines of block were not fixed but continuously changed on a beat-to-beat basis. In patients with persistent AF, the total length of block in the RA was more than 6-fold higher than during acute AF (median, 21.1 versus 3.4 mm/cm 2 ; P 2 ). The number of fibrillation waves during persistent AF was 4.5/cm 2 compared with 2.3 during acute AF, and the dissociation index was 7.3 versus 1.5 ( P Conclusions— Electric dissociation of neighboring atrial muscle bundles is a key element in the development of the substrate of human AF. The degree of the pathological changes can be measured on an individual basis by electrophysiological parameters in the spatial domain.

Long-term ECG recordings are of great value in the diagnosis and management of patients with cardiac arrhythmias. Information from programmed stimulation studies and intracardiac recordings has markedly improved the diagnostic abilities of the person examining the long-term ECG recording. This article discusses how knowledge from intracardiac electrophysiologic studies has resulted in much better recognition of the type and mechanisms of a supraventricular arrhythmia on the Holter record.

Incidence and timing of recurrences of sustained ventricular tachycardia (VT) or sudden death were studied in 206 patients who survived their first episode of ventricular fibrillation (VF; n = 52) or sustained VT (n = 154) after myocardial infarction. All patients were treated with (empirically selected) antiarrhythmic drugs; 49% received amiodarone. After a mean follow-up of 36 months, 64 patients (41%) in the VT group and 10 (19%) in the VF group had nonfatal VT recurrences. Sudden death occurred in 22 (14%) and 9 (17%) patients in the VT and VF groups, respectively. Incidence of sudden death had 2 peaks at approximately 3 and 12 months. Nonfatal VT recurrences were more frequent (most often occurring in first 6 months) in the VT than in the VF group. Sudden death occurred during the following 3 years in only 10% of patients who survived 1 year. There was a much higher incidence of sudden death in patients with left ventricular ejection fraction (LVEF) less than or equal to 40% than in those with LVEF greater than 40% (28 of 65 vs 3 of 141; p less than 0.0001), but no relation between LVEF and nonfatal VT recurrences.

Radiofrequency Ablation of Multiple Accessory Pathways. A 19-year-old patient is described having three accessory atrioventricular pathways. All three pathways were ablated using radiofrequency current in a single electrophysiologic investigation. (J Cardiovasc Electrophysiol, Vol. 3, pp. 141–149, April 1992)

The Metrix™ Atrioverter Expanded Indication Trial evaluates the safety and efficacy of an implantable atrial defibrillator in patients with symptomatic, recurrent and drug refractory atrial fibrillation who also have structural heart disease. In this ongoing multicenter study, all patients are anticoagulated and concomitant antiarrhythmic drug treatment is left to the preference of the physician. Holter monitoring is performed prior to enrollment in the study. Spontaneous episodes of atrial fibrillation (AF) are treated under physician observation and when patients are ambulatory, the device is programmed in a monitoring mode. The atrial defibrillation threshold is measured at implantation and at 3, 6 and 12 months thereafter. The performance of the AF detection and R-wave synchronization algorithm is assessed at implantation, at regular follow-up intervals, and each time the patient visits the hospital for treatment of a spontaneous episode of AF. An echocardiogram is performed prior to implantation, at 3 and 6 month follow-up and for patients with an implanted heart valve, after 20 and 50 atrial defibrillation shocks have been delivered. The study started on October 1997 and will end after the last patient enrolled completes his/her six-month post-implantation follow-up, unless a safety issue arises. As of September 1998, 6 patients (2 patients with tachycardia induced cardiomyopathy, 1 patient with a mitral valve prosthesis, 2 patients with hypertrophic cardiomyopathy and 1 patient with congenital heart disease) have been enrolled in the study. Over 350 shocks have been delivered for atrial defibrillation testing or termination of spontaneous AF episodes. There have been no reported cases of ventricular proarrhythmia or inaccurately synchronized shocks and no complications of device therapy in this population.

This is a 49-year-old male marathon runner with family history positive for coronary artery disease in both parents, and atrial fibrillation in the father.

Contains fulltext : 80026.pdf (Publisher’s version ) (Closed access) An 8-year-old girl who was recently diagnosed as having anaplastic large-cell lymphoma presented with atrial tachycardia and dilated cardiomyopathy, which is a contraindication for further treatment with cardio-toxic chemotherapy. After starting digoxin therapy, the dilated cardiomyopathy resolved. Repeated episodes of atrial tachycardia in this case were not caused by any common disorder but were due to mechanical stimulation by a central venous catheter. Central venous catheters are known to cause mainly ventricular arrhythmias. However, atrial tachycardia is a rare manifestation of arrhythmia due to mechanical stimulation of the heart by a central venous catheter, with potentially important cardiovascular consequences.

This is a 26-year-old male, with no known congenital or other cardiovascular disease in the family. No known cases of premature (

In 37 (70%) of 53 patients with idiopathic ventricular tachycardia (VT), episodes were mainly related to exercise (group 1). These patients were younger (33 +/- 14 vs 44 +/- 18 years, p = 0.015) and more often had dizziness during VT (71 vs 40%, p = 0.003) than the 16 patients in whom VT was not exercise-related (group 2). Patients in group 1 needed cardioversion less often to terminate the arrhythmia (4 (11%) vs 6 (40%), group 2 [p = 0.04]). VT was initiated during exercise testing in 62% of patients in group 1 but in only 1 patient in group 2 (p = 0.0004). Induction of clinical VT during programmed stimulation was observed in a similar percentage in group 1 (49%) and group 2 (50%) patients. Isoproterenol infusion facilitated the induction of VT in 9 of 20 (45%) group 1 and in 2 of 8 (25%) group 2 patients (p = not significant). After a mean follow-up of 2.9 +/- 2.5 years, 8 (22%) group 1 patients and 5 (31%) group 2 had at least 1 episode of symptomatic VT. Only 1 patient died suddenly. Class III drugs were the most useful in preventing recurrences. Beta-blocking agents were of little value in both groups. Patients with VT and a structurally normal heart have a good prognosis despite recurrences of their arrhythmia. The relation of the arrhythmia to exercise has no prognostic implications.

In some patients with atrial fibrillation, atrial flutter develops after administration of class IC antiarrhythmic drugs, the so-called class IC atrial flutter. Radiofrequency ablation of the right atrial isthmus results in clinical improvement in 85% of patients and provides an alternative management strategy for a subset of patients with therapy-resistant atrial fibrillation.

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.

Seven of 17 patients with incessant supraventricular tachycardia caused by an accessory pathway with a long retrograde conduction time were seen with symptoms or echocardiographic signs of a tachycardia-induced cardiomyopathy. Three patients were in New York Heart Association functional class II with dyspnea and four were in class III. Eight patients (six with tachycardia-induced cardiomyopathy) underwent surgery because of failure of medical treatment (including one patient in functional class I) and one underwent direct current catheter ablation of the atrioventricular (AV) node. In six patients echocardiograms recorded before and after the procedure were available. Before surgery or direct current ablation the mean left ventricular ejection fraction was 36.3 +/- 8.7%, the left ventricular end-diastolic diameter 55.7 +/- 7.6 mm and the left ventricular end-systolic diameter 44.3 +/- 7.8 mm. A mean of 21.6 +/- 6.8 months after the procedure the mean left ventricular ejection fraction increased to 58.6 +/- 8.0%, the left ventricular end-diastolic diameter decreased to 49.0 +/- 3.6 mm and the left ventricular end-systolic diameter decreased to 32.2 +/- 2.7 mm; all six patients were in functional class I. These results confirm that control of incessant tachycardia leads to a regression of symptoms and signs of cardiomyopathy and progressive normalization of the dimensions of the heart. Because of these findings, surgery should be considered early in patients with an accessory AV pathway and incessant tachycardia. The presence of a tachycardia-induced cardiomyopathy should therefore be an indication for surgery rather than a contraindication.

The 12 lead electrocardiographic (ECG) findings were reviewed in 17 patients having two or more accessory pathways as documented during electrophysiologic study in all 17 patients and by intraoperative mapping in 8.Twelve patients had findings suggesting the presence of more than one atrioventricular (AV) pathway. These were 1) more than one P wave configuration during orthodromic circus movement tachycardia (four patients); 2) a “mismatch” between the location of the ventricular and atrial ends of the accessory pathway as assessed when comparing exclusive AV and ventriculoatrial conduction over the accessory pathway during antidromic and orthodromic circus movement tachycardia, respectively (seven patients); 3) atrial fibrillation showing more than one pre-excitation pattern (six patients); 4) a spontaneous change from orthodromic to antidromic circus movement tachycardia and vice versa (two patients); 5) a spontaneous change from one type of antidromic tachycardia to another (two patients); and 6) a change in pre-excitation pattern after administration of a drug that prolongs the anterograde refractory period of the accessory pathway (three patients).The retrospective nature of this study does not allow conclusions as to the true value of the ECG in predicting the presence of more than one accessory pathway. This issue needs to be evaluated in a prospective study.

Of the accessory pathways, partially or totally bypassing the atrio-ventricular conduction system, the bundle of Kent is the most common type. The electrocardiographic (ECG) expression of preexcitation depends upon the contribution of the activation fronts over the AV node and the accessory pathway. From the polarity of the delta wave in the surface ECG and from the behavior during electrophysiologic study, the location of the accessory pathway can be derived. The presence of an accessory pathway may induce circus movement tachycardia and, in case of atrial fibrillation, high ventricular rates possibly leading to sudden death. Noninvasive techniques are able to identify the patient at high risk. Treatment modalities are pharmacologic or surgical, whereas ablation techniques are still under investigation.

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).

Background — The goal of this study was to test the hypothesis that the occurrence of atrial fibrillation (AF), in at least some patients with coexisting type I atrial flutter (AFL), is based on macro-reentry around the tricuspid valve orifice, including the right atrial (RA) isthmus, by evaluation of the AF recurrences after successful ablation of AFL. Methods and results — Eighty-two consecutive patients with type I AFL, with or without concomitant AF, underwent radiofrequency ablation (RFA) of the RA isthmus by an anatomical approach. The results were analyzed in 4 groups of patients: group 1 (only AFL; 29 patients), group 2 (AFL > AF; 22 patients), group 3 (AF > AFL; 15 patients), and group 4 (developing AFL while receiving class IC antiarrhythmic drug therapy for AF, the ‘class IC atrial flutter’; 16 patients). In all groups, RFA of type I AFL was performed with a high (≥ 93%) procedural success rate. In group 1, only 2 patients (8%) had AF after (18 ± 14 months) AFL ablation. These figures were 38% (20 ± 14 months) and 86% (13 ± 8 months) in groups 2 and 3, respectively. Group 4 patients (4 ± 2 months) had a 73% freedom of AF recurrences with continuation of the class IC agent. Conclusions — The low incidence of new AF during long-term follow-up after RFA of type I AFL makes it unlikely that radiofrequency lesions promote the development of AF. The impact of isthmus ablation on AF recurrences differs according to the clinically predominant atrial arrhythmia and suggests a possible role of the RA isthmus in the occurrence of AF in some patients. Ablation of class IC atrial flutter in patients with therapy-resistant AF is a novel approach to management of this patient subset. Careful classification of AF patients plays a role in the selection of the site of ablation therapy (Circulation 99: 1441-1445, 1999).

Background —The goal of this study was to test the hypothesis that the occurrence of atrial fibrillation (AF), in at least some patients with coexisting type I atrial flutter (AFL), is based on macro-reentry around the tricuspid valve orifice, including the right atrial (RA) isthmus, by evaluation of AF recurrences after successful ablation of AFL. Methods and Results —Eighty-two consecutive patients with type I AFL, with or without concomitant AF, underwent radiofrequency ablation (RFA) of the RA isthmus by an anatomical approach. The results were analyzed in 4 groups of patients: group 1 (only AFL; 29 patients), group 2 (AFL >AF; 22 patients), group 3 (AF >AFL; 15 patients), and group 4 (developing AFL while receiving class IC antiarrhythmic drug therapy for AF, the “class IC atrial flutter”; 16 patients). In all groups, RFA of type I AFL was performed with a high (≥93%) procedural success rate. In group 1, only 2 patients (8%) had AF after (18±14 months) AFL ablation. These figures were 38% (20±14 months) and 86% (13±8 months) in groups 2 and 3, respectively. Group 4 patients (4±2 months) had a 73% freedom of AF recurrences with continuation of the class IC agent. Conclusions —The low incidence of new AF during long-term follow-up after RFA of type I AFL makes it unlikely that radiofrequency lesions promote the development of AF. The impact of isthmus ablation on AF recurrences differs according to the clinically predominant atrial arrhythmia and suggests a possible role of the RA isthmus in the occurrence of AF in some patients. Ablation of class IC atrial flutter in patients with therapy-resistant AF is a novel approach to management of this patient subset. Careful classification of AF patients plays a role in the selection of the site of ablation therapy.

Immediate Reinitiation of AF. Introduction: Although the recurrence rate of atrial fibrillation has been reported to be similar to that after external and internal cardioversion, little is known about immediate reinitiation of atrial fibrillation (IRAF) following internal cardioversion. Methods and Results: Thirty-eight patients (24 men; mean age 63 ± 13 years) underwent internal atrial defibrillation. Catheter-based defibrillation electrodes were positioned in the anterolateral right atrium and the coronary sinus. All patients were cardioverted at a mean threshold of 4.6 ± 3.4 J. Five of 38 patients (13%) had 1 to 4 episodes of IRAF. No difference in clinical and echocardiographic characteristics were observed when patients with and without IRAF were compared. Atrial fibrillation was always reinitiated by an atrial premature beat. When the earliest atrial endocardial activation time on the defibrillation catheters was analyzed, these atrial premature heats did not seem to originate from the defibrillation catheters. Twenty-one patients had atrial premature heats without IRAF. When the coupling intervals of the first atrial premature heat in patients without and with IRAF after conversion were compared, a significant difference was found (661 ± 229 vs 418 ± 79 msec, P < 0.05). IRAF was successfully treated with repeated shock delivery after the administration of atropine in 1 patient and intravenous flecainide in 2. Only repeated shock delivery was sufficient to treat IRAF in another 2 patients. Late recurrences of atrial fibrillation occurred in 3 of 5 with IRAK and in 19 of 33 patients without IRAF (P = NS). Conclusion: IRAF after internal atrial defibrillation occurred in 13% of patients, was always initiated by an atrial premature heat having a short coupling interval not originating from the defibrillation catheters, and was prevented by repeated shock delivery with or without preceding administration of pharmacologic agents. IRAF did not predict early recurrences of the arrhythmia after discharge from the hospital, emphasizing the necessity to treat immediate reinitiation promptly to achieve a successful cardioversion.

This study reports on predictors for successful radiofrequency (RF) ablation of idiopathic ventricular tachycardia (VT) in 48 patients--35 with right ventricular (RV) outflow tract and 13 with left ventricular VT. In RV outflow tract idiopathic VT, RF ablation was successful in 29 of 35 patients (83%). The following information allowed differentiation between patients with and without a successful RF ablation:1 induced VT morphology (O vs 3); presence of delta wave-like beginning of the QRS (2 vs 3) andor = 11 of 12 leads showing a "match" between the clinical VT and the pacemap (28 vs 1). Endocardial activation times were not different between both groups (-15 +/- 18 vs -4 +/- 5 ms). In left ventricle idiopathic VT, RF ablation was successful in 12 of 13 patients (92%). In patients who underwent successful ablation, 1 VT morphology was induced and no delta wave-like beginning of the QRS was present; a correlation between clinical VT and the pacemapor = 11 of 12 leads was found and the endocardial activation time preceded the QRS (range of -5 to -58 ms [mean -30 +/- 14]). Purkinje activity was observed in 5 of 7 patients with an idiopathic VT originating from the inferoposterior region but not from the inferoapical region of the left ventricle. Four patients (14%) with RV outflow tract idiopathic VT had recurrence during a mean follow-up of 2 to 50 months (mean 30 +/- 12). Thus, (1) in RV outflow tract idiopathic VT a good pacemap was more important than an early endocardial activation time; (2) an optimal pacemap as well as an early endocardial activation time were important predictors for successful ablation of the left ventricle idiopathic VT; (3) Purkinje activity was recorded in VTs arising in the inferoposterior region of the left ventricle; and (4) factors for unsuccessful ablation for idiopathic VT were1 induced VT morphology, a delta wave-like beginning of the QRS, and a VT/pacemap correlation11 of 12 leads. Idiopathic VT can be successfully ablated with both immediate and long-term success.

Answer to the rhythm puzzle The ECG shows a total atrioventricular block with junctional escape complexes, although the ninth QRS complex may be conducted. The second and eighth QRS complexes result from a retrogradely conducted P wave (Fig. 2). This mechanism, in which an escape complex is followed by a conducted complex, is called an escape-capture bigeminy. This only happens if the R-P interval of the retrograde P wave is long enough (along the slow AV nodal pathway) to be conducted back to the ventricles along the fast AV nodal pathway. When the P wave is caused by retrograde conduction along the fast AV nodal pathway, anterograde AV nodal conduction is blocked, resulting in a blocked P wave (after the third, fifth and (probably) tenth QRS complex). Fig. 2 Ladder diagram of a retrograde P wave conducted back to the ventricles and a blocked retrograde P wave Lithium intoxication was diagnosed based on the clinical symptoms (sinus node dysfunction and lethargy) and on a serum level of 0.88 mmol/l which is considered to be toxic at this age. Since lithium treatment was considered to be the most beneficial therapy for this patient, a DDD pacemaker was implanted. This was done successfully and without any complications, after which she was discharged from our centre.

Ablation of an Anterior Fascicular Idiopathic VT. Introduction: Idiopathic ventricular tachycardia (VT) originating in or close to the anterior fascicle of the left bundle is rare. A patient with no structural heart disease and VT with a right bundle branch block configuration and right-axis deviation underwent an electrophysiologic examination. Methods and Results: Both endocardial activation mapping during VT and pacemapping were performed via a transseptal approach to localize the site of origin of the VT. Endocardial recordings of the His bundle and the posterior and anterior fascicles of the left bundle branch revealed an origin of the VT in or close to the anterior fascicle. The Purkinje potential at that site preceded the QRS complex by 20 msec, with pacemapping showing an optimal match between the paced rhythm and the clinical VT. RF energy delivered at this site terminated the VT. A left anterior nemiblock appeared after RF ablation. Ten months later, the patient is free from recurrences of VT. Conclusions: Idiopathic VT originating in or close to the anterior fascicle was cured by RF ablation. A Purkinje potential preceding the QRS during tachycardia and an optimal pacemap were used to guide RF ablation.

OBJECTIVE: To determine the features that distinguish bundle branch reentry (BBR) ventricular tachycardia from a supraventricular tachycardia with aberration on the 12 lead electrocardiogram (ECG). PATIENTS: Three patients in whom premature beats (2 cases) or sustained tachycardia (2 cases) showed a QRS configuration identical to that observed during sinus rhythm. INTERVENTIONS: Programmed electrical stimulation. RESULTS: These arrhythmias were ventricular in origin and caused by a BBR mechanism, as suggested by the following data obtained during electrophysiological study: (a) an H-V interval shorter during tachycardia than during sinus rhythm; (b) A-V dissociation; (c) activation of the right bundle branch before activation of the bundle of His. The ECG of all 3 patients showed right bundle branch block with very prolonged QRS duration (0.16 to 0.20 s). Characteristically, all 3 had prolonged H-V interval during sinus rhythm. All patients had had a previous myocardial infarction and had a dilated left ventricle. CONCLUSION: The presence of (a) wide complex extrasystoles or tachycardia with a QRS morphology identical to that of sinus rhythm; (b) A-V dissociation; and (c) a very prolonged QRS duration (0.16 s or more) is suggestive of ventricular tachycardia caused by bundle branch reentry.