Fasciculoventricular and atrioventricular accessory pathways in patients with Danon disease and preexcitation: A multicenter experience.

BACKGROUND: Studies have suggested that a fasciculoventricular pathway (FVP) may be the cause of preexcitation in patients with Danon disease, a rare X-linked dominant genetic disorder of hypertrophic cardiomyopathy. OBJECTIVE: The purpose of this study was to describe the prevalence of ventricular preexcitation on resting 12-lead electrocardiogram (ECG) in patients with Danon disease and the electrophysiological study (EPS) results of those with preexcitation. METHODS: Patients with confirmed Danon disease diagnosed with preexcitation (PR ≤120 ms, delta wave, QRS >110 ms) on ECG were included from a multicenter registry. The incidence of arrhythmias, implantable cardioverter-defibrillator (ICD) procedures, ICD shocks, and EPS results were collected. RESULTS: Thirteen of 40 patients (32.5%) with Danon disease were found to have preexcitation (mean age 17.3 years; 38% women). EPS performed in 9 of 13 patients (69%) demonstrated FVP only in 2 (22.2%), extranodal pathway without exclusion of FVP in 2 (22.2%), and both FVP and extranodal pathway in 5 (55.6%). Two patients had malignant accessory pathway (AP) properties. Over median follow-up of 842 days (interquartile range 138-1678), 11 patients (85%) had ICD placement, and 6 (46.1%) underwent heart transplantation. No patients required therapy for ventricular tachycardia, and 2 patients (15%) had paroxysmal atrial fibrillation. CONCLUSION: In a large multicenter cohort of patients with Danon disease, there was a high prevalence of FVP and extranodal pathways diagnosed on EPS in those with preexcitation. These findings suggest patients with preexcitation and Danon disease should undergo EPS to assess for FVP and potentially malignant extranodal AP.

Radiofrequency ablation for the pre-excitation syndrome of functionally corrected transposition of great arteries.

We reported a 57-year-old female patient who had functionally corrected transposition of the great arteries, severe tricuspid insufficiency, enlarged left atrium and functional right ventricle, which were successfully performed radiofrequency ablation.

Paradoxical preexcitation during cryoablation of a concealed parahisian accessory pathway.

A 16-year-old male presented with an orthodromic atrioventricular reentrant tachycardia over a concealed parahisian accessory pathway (AP). Cryoablation of the AP resulted in transient manifestation of a fully preexcited sinus rhythm of parahisian AP morphology. Potential causes for the paradoxical preexcitation include inadvertent atrioventricular nodal block, sourse-sink mismatch, as well as the activation of a dormant AP capable of anterograde conduction.

Apoptosis and epicardial contributions act as complementary factors in remodeling of the atrioventricular canal myocardium and atrioventricular conduction patterns in the embryonic chick heart.

BACKGROUND: During heart development, it has been hypothesized that apoptosis of atrioventricular canal myocardium and replacement by fibrous tissue derived from the epicardium are imperative to develop a mature atrioventricular conduction. To test this, apoptosis was blocked using an established caspase inhibitor and epicardial growth was delayed using the experimental epicardial inhibition model, both in chick embryonic hearts. RESULTS: Chicken embryonic hearts were either treated with the peptide caspase inhibitor zVAD-fmk by intrapericardial injection in ovo (ED4) or underwent epicardial inhibition (ED2.5). Spontaneously beating embryonic hearts isolated (ED7-ED8) were then stained with voltage-sensitive dye Di-4-ANEPPS and imaged at 0.5-1 kHz. Apoptotic cells were quantified (ED5-ED7) by whole-mount LysoTracker Red and anti-active caspase 3 staining. zVAD-treated hearts showed a significantly increased proportion of immature (base to apex) activation patterns at ED8, including ventricular activation originating from the right atrioventricular junction, a pattern never observed in control hearts. zVAD-treated hearts showed decreased numbers of apoptotic cells in the atrioventricular canal myocardium at ED7. Hearts with delayed epicardial outgrowth showed also increased immature activation patterns at ED7.5 and ED8.5. However, the ventricular activation always originated from the left atrioventricular junction. Histological examination showed no changes in apoptosis rates, but a diminished presence of atrioventricular sulcus tissue compared with controls. CONCLUSIONS: Apoptosis in the atrioventricular canal myocardium and controlled replacement of this myocardium by epicardially derived HCN4-/Trop1- sulcus tissue are essential determinants of mature ventricular activation pattern. Disruption can lead to persistence of accessory atrioventricular connections, forming a morphological substrate for ventricular pre-excitation. Developmental Dynamics 247:1033-1042, 2018. © 2018 Wiley Periodicals, Inc.

Preexcitation syndrome: experimental study on the electrocardiogram of antegradely conducting accessory pathway.

BACKGROUND: Preexcitation syndrome is characterized by a dominant delta wave on the baseline electrocardiogram (ECG), resulting from the change in QRS initial vector by the accessory pathway (AP). This study is to explore the effect of ventricular preexcitation on the QRS initial, maximal and terminal vector in an experimental rabbit with preexcitation syndrome induced by programmed electrical stimulation. METHODS: Rabbits (n = 10) were randomized for the experimental model of ventricular preexcitation. Sensing and stimulating electrode catheters were placed in the high right atrium and along epicardial surface of atrioventricular groove of the left ventricular anterior wall, respectively. Programmed premature stimulation S2 was synchronized with P wave and utilized to stimulate the ventricle. The ECG recorded the electrical activity of the heart. As compared with the QRS complex during sinus rhythm, paced QRS was assessed regarding the initial, maximal and terminal vector. PS2 interval and PR interval were also measured and analyzed. RESULTS: Preexcitation was successfully simulated by ventricular pacing in the rabbits, including (1) Complete preexcitation: PS2 interval was less than PR interval; the difference was more than or equal to 47.00 ± 7.53 ms. (2) Incomplete preexcitation: PS2 interval was less than PR interval; the difference was less than 47.00 ± 7.53 ms. (3) Incomplete latent preexcitation: PS2 interval was more than or equal to PR interval; the difference was less than or equal to 13.00 ± 3.50 ms. (4) Complete latent preexcitation: PS2 interval was more than or equal to PR interval; the difference was more than 13.00 ± 3.50 ms. CONCLUSIONS: The difference in the relative conduction velocity of the atrioventricular node versus the AP pathways determines the degree of preexcitation and different manifestation on ECG. The QRS terminal vector also reflects the ventricle preexcitation, indicating a valuable sign for the diagnosis of atypical or latent preexcitation.

[ECG results: tips and tricks for the correct diagnosis : Bradycardia and tachycardia rhythm disorders]. / EKG-Befunde: Tipps und Tricks zur richtigen Diagnose : Bradykarde und tachykarde Rhythmusstörungen.

The 12-lead surface electrocardiogram (ECG) is of great importance for the diagnostics of cardiac arrhythmias. For the correct and systematic analysis it has a sensitivity and specificity for the correct diagnosis of supraventricular tachycardia or ventricular tachycardia of more than 95%. Nevertheless, the assessment of cardiac rhythm disorders is difficult for many physicians. In this way errors can occur, frequently due to a non-systematic analysis of the ECG; therefore, the aim of this article is to present the techniques and the necessary knowledge for assessment of the most frequent bradycardiac and tachycardiac heart rhythm disorders. Additionally, special features in the analysis of the ECG results in children are discussed.

Pseudo-preexcitation is prevalent among patients with repaired complex congenital heart disease.

This study aimed to evaluate the prevalence of preexcitation and possible pseudo-preexcitation among patients undergoing complex congenital heart surgery at a single center. During a 6-year period (2007-2013), the study retrospectively reviewed the electronic medical records and electrocardiograms (ECGs) of 98 patients who had undergone complex cardiac surgery at the University of Iowa Children's Hospital. The presence and timing of delta waves or short PR interval were evaluated as well as the results of testing for the presence of an accessory pathway. The ECG of 17 patients (17.3%) showed delta waves. Eight of these patients also had a short PR interval. A significant majority of the 17 patients (n = 13) with delta waves showed hypoplastic left heart syndrome (HLHS), with atrioventricular canal defect and Ebstein's anomaly also represented. Two patients with delta waves had adenosine testing that showed antegrade conduction block, greatly reducing the likelihood of an accessory pathway. One patient with delta waves had an electrophysiology study demonstrating an accessory pathway, and the remaining patients had no additional testing for an accessory pathway. For 12 patients, the findings showed a short PR interval on at least one ECG with no evidence of delta waves. Delta waves were commonly seen in patients with HLHS and less commonly in patients with other diagnoses. The high prevalence of preexcitation in combination with our testing confirmed the lack of an accessory pathway in the presence of a delta wave, suggesting that pseudo-preexcitation may be a frequent finding. A short PR interval also was seen frequently in patients exhibiting HLHS, with and without the presence of a delta wave.

Diagnóstico electrocardiográfico de vía accesoria fasciculoventricularl / Electrocardiographic diagnosis of fasciculoventricular accessory pathway

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Prevalence, causes of reappearance of symptoms or preexcitation syndrome after ablation of accessory pathway and management.

AIM: The purpose of the study was to look for the prevalence, significance and management of preexcitation syndrome (PS) or symptoms reappearance after accessory pathway (AP) ablation. AP ablation actually is the first treatment of PS. METHODS: Successful AP ablation was performed in 261 patients; reappearance of symptoms or PS on ECG occurred in 47 patients (18%) from 20minutes to several years. Their data were compared with remaining patients. RESULTS: Recurrences were more frequent in patients with spontaneous malignant form (34 vs. 21%), in congenital heart disease (4.2 vs. 0%) (P<0.002), in case of complication (11 vs. 2%) (P<0.007) and of a longer duration of applications (304±209 vs. 188±182sec) (P<0.019). Forty percent of patients had the same symptoms and electrophysiological data as before ablation. Twenty-four percent had an improvement of symptoms and/or electrophysiological data. However, 3 initially asymptomatic patients became symptomatic after ablation. Twenty-six percent had another AP or another rhythm disorder. We recommend transesophageal electrophysiological study for the control because only 40% of patients required second ablation. CONCLUSIONS: Reappearance of symptoms or a PS on ECG after AP ablation was not rare (18%) and was inconsistently associated with the reappearance of all initial AP electrophysiological properties. Only 40% of patients required a second AP ablation. Another arrhythmia was possible. Non-invasive second evaluation should be preferred. However, asymptomatic patients before ablation could become symptomatic.

Radiofrequency ablation of a left accessory pathway unmasks classic Chagas' disease ECG pattern.

In patients with chronic Chagas' cardiomyopathy, there are forms of the disease that affect the electrical conduction system almost exclusively. The most common disorders include right bundle branch block alone or in association with left anterior fascicular block. We present an unusual case of a patient with Chagas' cardiomyopathy in association with a preexcitation syndrome.

Superior left ventricle in combination with inferior right ventricle: presenting with balanced hemodynamics and mild symptoms in a late adolescent.

We describe a case of superoinferior ventricles with an unusual superior location of the left ventricle and inferior location of the right ventricle. The patient was a 17-year-old boy who had been admitted for paroxysmal supraventricular tachycardia with pre-excitation syndrome. The cardiac anomaly was first recognized after admission, and the pre-excitation syndrome, eventually, was treated successfully by radiofrequency catheter ablation. This case featured a segmental set notation {S, D, S} with concordant atrioventricular and ventriculoarterial alignments. Persistent left superior vena cava was the only associated defect. To the best of our knowledge, there has been only 1 other reported case of superoinferior ventricles in which the left ventricle was in the superior position. In our case, the patient's hemodynamics were sufficiently normal that he had reached adolescence with only minor adverse events.

The appearance of ventricular preexcitation during exercise testing reproduced by dobutamine administration.

A 33-year-old woman presented with exercise-related palpitations after an apparently successful catheter-ablation of overt midseptal accessory pathway. Post procedure, the electrocardiogram at rest was normal, while the progressive appearance of delta-wave during treadmill stress testing was recorded. In addition, the occurrence of ventricular preexcitation was reproduced by controlled administration of dobutamine. Detailed understanding of the unusual pathway electrophysiology resulted in specific planning of the second procedure. In the basal state, pacing maneuvers did not demonstrate any evidence of pathway conduction. However, during infusion of dobutamine bidirectional conduction in the right anterior pathway was restored, enabling definitive cure by radiofrequency.

Isolated left ventricular non-compaction cardiomyopathy associated with ventricular preexcitation: a case report.

Isolated left ventricular non-compaction (ILVNC) is one of the most misclassified cardiomyopathies. It is caused by failure of normal embryonic development of the myocardium from loosely arranged muscle fibers to the mature compacted form of myocardium, but it seems that etiology is not exclusively congenital. Diagnosis of ILVNC is mostly missed because of lack of awareness and knowledge. The recognition of the disease is mandatory, because of its high mortality and morbidity due to the progressive heart failure, thromboembolic events and lethal arrhythmias. We report of a family in which two adult members were found to have ILVNC. A literature review about ILVNC pathogenesis, diagnosing, and treatment was discussed.