ECG de marzo de 2018 / ECG, March 2018

No disponible

Successful cryoablation of Mahaim tachycardia in a child with Ebstein's anomaly.

Mahaim fibers with decremental atrioventricular (AV) node-like conduction properties comprise less than 3 % of accessory pathways. Radiofrequency ablation of right atriofascicular pathways guided by a distinct Mahaim potential detected at the anterolateral to posterolateral tricuspid annulus or in the right ventricular free wall is a safe and highly effective treatment method. The case report presents a 16-year-old boy with Ebstein's anomaly and symptomatic wide complex tachyarrhythmia. The electrophysiologic study and the entire ablation procedure were performed using a three-dimensional mapping system (EnSite Velocity; St. Jude Medical Inc., St. Paul, MN, USA). No fluoroscopy was used during the procedure. Electrophysiologic evaluation demonstrated typical atrioventricular nodal reentrant tachycardia and Mahaim tachycardia with a wide QRS and a left bundle branch block pattern. After Mahaim potential was located at the lateral tricuspid annulus, successful cryoablation was performed with an 8-mm-tip catheter followed by slow pathway ablation to eliminate typical atrioventricular nodal reentrant tachycardia. Cryoablation with an 8-mm-tip catheter can be an alternative treatment option for children with Mahaim tachycardia.

An unusual preinduction arrhythmia resulting from the presence of a Mahaim fiber.

A potentially life-threatening arrhythmia appeared on the preinduction electrocardiogram of an asymptomatic young woman prior to spine surgery. The patient was evaluated by electrophysiology and had a rare accessory pathway, a Mahaim Fiber.

The clinical course and risk in patients with pseudo-Mahaim fibers.

BACKGROUND: Pseudo-Mahaim (AP-M) fibers are a rare variant of atrioventricular (AV) accessory pathways. Atriofascicular and atrioventricular accessory connections are characterized by slow conduction and decremental properties. Dual physiological AV node pathways, slow and fast, are observed in a large number of patients with AP-M. Therefore, there is substrate for AV nodal reentrant tachycardia (AVNRT) in addition to antidromic AV reentrant tachycardia (AVRT) with left bundle branch block (LBBB)-like morphology. Other arrhythmia such as atrial fibrillation (AF) or atrial flutter (AFL) and ventricular fibrillation (VF) are also observed. We analysed the occurrence of arrhythmias in a group of patients with AP-M treated in our department. METHODS: We evaluated 27 patients (12 women) aged 14-53 years (mean age 25.6 years) with AP-M. The clinical course in these patients, in particular with regard to the occurrence of arrhythmias, was analysed. Patients with dual AV node properties were compared to patients without such findings. RESULTS: We found dual AV node properties in 18 patients (Group 1), while 9 patients had fast pathway only (Group 2). Twenty-six patients presented with AVRT, 2 patients with AVNRT, 3 patients with AF, 1 patient with AT, 2 patients with AFL, and 3 patients with VF. In 2 patients, AP-M were seen in an atypical area. In one patient, the pathway connected the right atrium with the left ventricle (septal region), and in the other patient it connected the left atrium with the left ventricle (left anterior region). CONCLUSIONS: The majority of AP-M was right-sided. Two thirds of patients with AP-M had anatomical substrate for AVNRT (fast/slow pathway AV node). VF or asystole occurred in 10% of patients.

A single Mahaim fiber causing both antidromic and orthodromic reciprocating tachycardia.

We describe the case of a 56-year-old woman referred for electrophysiological (EP) testing for medically refractory supraventricular arrhythmias. During the EP study, the patient was found to have a right free wall atriofasicular (Mahaim type) accessory pathway and an inducible left bundle morphology preexcited tachycardia secondary to antidromic reciprocating tachycardia. The patient also had an inducible narrow complex orthodromic reciprocating tachycardia (ORT). Mapping revealed that the earliest site of retrograde atrial activation during ORT was along the lateral tricuspid annulus. This was the same location where the atriofasicular accessory pathway potential was recorded during sinus rhythm. Radiofrequency ablation at this site eliminated inducibility of both tachycardias and any evidence of antegrade or retrograde accessory pathway conduction. This report describes the case of a very rare right free wall Mahaim type fiber with both antegrade and retrograde conduction capabilities responsible for both antidromic and ORT.

Entrainment mapping of a concealed nodoventricular accessory pathway in a man with complete heart block and tachycardia-induced cardiomyopathy.

True nodoventricular (NV) accessory connections, as originally described by Mahaim, are rare entities, with the majority of previously reported cases now recognized as being due to decremental atriofascicular pathways. Here, we present a patient with incessant narrow and wide QRS complex tachycardia occurring in the setting of prior complete heart block. Entrainment mapping proved useful in diagnosing orthodromic reentry utilizing a concealed right septal NV pathway. The patient was successfully treated with radiofrequency ablation, resulting in a marked improvement in left ventricular function.

Cryoablation of a nodoventricular Mahaim fiber.

An 11-year old female presented with paroxysmal tachycardia and was diagnosed with a Mahaim fiber during electrophysiologic study. A preexcited tachycardia and the typical variety of AV nodal reentry tachycardia were induced at different times. During preexcited tachycardia, the His bundle electrogram followed the ventricular electrogram, and, introduction of atrial premature beats at different coupling intervals, advanced the peri-AV nodal atrial tissue, with no change in the ventricular cycle length, leading to a diagnosis of an antidromic tachycardia due to a nodoventricular fiber. Cryoablation at a mid-septal location under three-dimensional guidance successfully eliminated both tachycardias without detrimental effects to the AV node.

Latent Mahaim fiber as a cause of antidromic reciprocating tachycardia: recognition and successful radiofrequency ablation.

The term "Mahaim fiber" usually is applied to an atriofascicular fiber that inserts distally into the right bundle branch and forms the anterograde limb of a reciprocating tachycardia. One of the features that has been used to describe the physiology of Mahaim fibers is the presence of anterograde preexcitation. We describe two patients who had a clinical tachycardia consistent with a "Mahaim tachycardia" in whom there was no evidence or minimal evidence of anterograde preexcitation during sinus rhythm or atrial pacing. In both patients, the tachycardia was rendered noninducible by radiofrequency ablation at the site of Mahaim potentials at the tricuspid annulus, and a long-term cure was achieved. This is the first description of a "latent Mahaim fiber" that does not cause preexcitation but which can support antidromic reciprocating tachycardia.

Taquicardia supraventricular secundaria a síndrome de preexcitación de tipo Mahaim / Supraventricular tachycardia secondary to Mahaim-type preexcitation syndrome

Presentamos el caso de un individuo joven que acude al Servicio de Urgencias, por segunda vez, presentando un cuadro oligosintomático caracterizado por la presencia de palpitaciones y cuyo electrocardiograma basal muestra una taquicardia de origen sinusal con depresiones significativas del segmento ST en derivaciones precordiales que podrían hacer pensar en la existencia de una coronariopatía. Una vez realizado el estudio se demuestra la existencia de un síndrome de preexcitación cuya vía se define como del tipo Mahaim, cuya tasa de presentación es relativamente escasa y cuyos criterios electrocardiográficos vienen definidos por la existencia de un intervalo PR correspondiente a la conexión auriculoventricular que no se aparta de la normalidad eléctrica (>12 milisegundos) y un ventriculograma en el que llama la atención la prolongación en el tiempo del complejo de despolarización (QRS superior a 12 milisegundos) y la existencia de anomalías significativas en la repolarización ventricular (depresión de segmento ST).Destacamos la aparición de cuadros de taquicardia supraventricular, de origen sinusal, secundarias a la existencia de este síndrome de preexcitación de tipo Mahaim como forma de presentación de cuadros de taquiarritmia en corazones estructuralmente sanos y que a pesar de las anomalías en la repolarización están exentos de presentación de cardiopatía coronaria. Las implicaciones pronósticas y terapéuticas derivadas de la aceptación de este modelo se traducen no ya sólo en la posibilidad de ingreso urgente sino en la indicación de tratamiento antiarrítmico o antianginoso (AU)

Syncope and preexcitation: a case of a Kent and fasciculoventricular Mahaim fibers.

A case involving an 8-year-old girl with syncope and preexcitation on a surface electrocardiogram (ECG) that was suggestive of Wolff-Parkinson-White syndrome is presented. An intracardiac electrophysiologic study revealed a posteroseptal bidirectionally conducting Kent fiber. Radiofrequency ablation of the Kent fiber was successful, but the patient had a residual short His-ventricular (HV) interval and a new preexcitation pattern. Atrial extra stimuli and ventricular pacing revealed a fixed, preexcited QRS. Nodal block and loss of preexcitation was provoked with adenosine. The surface QRS and electrophysiologic features are consistent with a left septal fasciculoventricular Mahaim fiber.

Preexcitation in hypertrophic cardiomyopathy: a case of a fasciculoventricular Mahaim fiber.

A patient with hypertrophic cardiomyopathy (HCM) who presented with preexcitation pattern on the surface ECG suggestive of the Wolff-Parkinson-White (WPW) syndrome is described. Intracardiac electrophysiological study revealed a fixed anomalous QRS complex and a short-fixed His-ventricular interval indicating a fasciculoventricular Mahaim fiber. As this specific form of accessory connection does not cause reentrant tachycardias, no treatment was required. It is important to distinguish this entity from atriofascicular or nodoventricular Mahaim fibers or the WPW syndrome in patients with HCM showing a preexcitation pattern in the surface ECG, as these may cause life-threatening arrhythmias in this patient population.

Regular narrow QRS complex tachycardias in the Manitoba Follow-up Study (1948-88).

OBJECTIVE: To determine the incidence, risk factors and prognosis of regular narrow QRS complex tachycardia (NQT), which develops in the absence of pre-excitation in subjects free from ischemic heart disease in the Manitoba Follow-up Study. DESIGN AND SETTING: The Manitoba Follow-up Study is a longitudinal cardiovascular study of 3983 initially healthy men (primarily living in Canada) followed prospectively for 40 years. Risk factors and prognosis were assessed in a nested case-control study. MAIN RESULTS: Twenty-two individuals were diagnosed with NQT before clinical and/or electrocardiographic manifestation of ischemic heart disease (145,408 person-years of observation). Between the ages of 30 and 80, the incidence of NQT was one per 6000 person-years and increased with age. History of childhood diseases, valvular disease, smoking, elevated blood pressure and body mass index did not increase the likelihood for NQT development. NQT was diagnosed concurrently with a serious noncardiac condition in seven cases; excess mortality resulted as six of these subjects died within one year of NQT diagnosis while only two subjects without concurrent disease at NQT diagnosis died during follow-up. In comparison with 2% of control subjects, 27% of subjects with NQT subsequently developed electrocardiographical evidence of atrial fibrillation (relative risk was 12 with lower 95% confidence limit of 1.8). CONCLUSIONS: NQT in an otherwise healthy individual is a benign condition and increases the likelihood of atrial fibrillation development.

Diagnosis and surgical treatment of tachycardias in patients with nodoventricular fibers.

From May, 1982 to April, 1991 25 patients were examined and 23 had open heart surgery for tachycardia with nodoventricular fibers (NVF) participation. All patients suffered tachycardia for more than 5 years. Most patients had syncope. The patients had: true NVF tachycardia (11), atrioventricular node reentry tachycardia (5), orthodromic atrioventricular tachycardia (AVT) (5), and atrial flutter (1) all with passive propagation through NVF, pseudonodoventricular tachycardia (AVT with slow accessory pathways) two patients. In 18 out of the 23 who had surgery there were no signs of preexcitation or tachycardia events in the follow-up period.

Successive myocardial infarctions in a patient with Mahaim fiber syndrome.

A patient with Mahaim fiber syndrome suffered two acute myocardial infarctions during the last two years. Anomalous atrioventricular excitation was intermittent. Diagnosis of both anteroseptal and anterolateral electrocardiographic myocardial infarction could be made despite ventricular pre-excitation. These findings have not been previously published, to our knowledge.