A mutation in the Z-line Cypher/ZASP protein is associated with arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an important cause of malignant arrhythmia and sudden death particularly in young people. Although it is considered a desmosomal disease, mutations in non-desmosomal genes have also been identified. We report on a family where a mutation in LDB3 is associated with this condition. The index case and first and second degree relatives underwent a complete clinical evaluation: physical examination, electrocardiography (ECG), signal-averaged ECG, 2D echocardiogram, cardiac magnetic resonance and 24-h monitoring. After ruling out mutations in the five desmosomal genes, genetic testing by means of Next Generation Sequencing was carried out on the proband. A heterozygous missense mutation in LDB3 c.1051A>G was identified. This result was confirmed by subsequent Sanger DNA sequencing. Another six carriers were identified amongst her relatives. Three subjects fulfilled the criteria for a definitive diagnosis of ARVC and one reached a borderline diagnosis. In conclusion, this is the first family with ARVC where a mutation in LDB3 is associated with ARVC. Next generation sequencing arises as a particular useful tool to point to new causative genes in ARVC.

[Transient atrial fibrillation induced by adenosine in a patient with atrial tachycardia]. / Fibrilación auricular transitoria inducida por adenosina en una paciente con taquicardia auricular.

The administration of adenosine during atrial tachycardia usually terminates the arrhythmia or induces AV block and makes the diagnosis clear. We present a patient with atrial tachycardia in which the administration of adenosine induced a transient atrial fibrillation (AF). A continuous transition between both arrhythmias was observed and the original tachycardia persisted after the termination of the AF. This proarrhythmic effect may be due to the adenosine-mediated shortening of the atrial refractory periods, which produces a decreased wavelength of the reentry circuits and the potential coexistence of several wave-fronts in the atria, favoring the development of AF. The recognition of this uncommon effect is important, since the repeated administration of increasing doses of adenosine may induce sustained AF.

Fibrilación auricular transitoria inducida por adenosina en una paciente con taquicardia auricular / Adenosine-induced transient atrial fibrillation in a patient with atrial tachycardia

La administración de adenosina durante taquicardia auricular suele producir la terminación de la misma o aumentar el grado de bloqueo AV facilitando su diagnóstico. Presentamos un caso de inducción de fibrilación auricular (FA) transitoria por adenosina en una paciente con taquicardia auricular. La transición entre ambos ritmos fue contínua, persistiendo la taquicardia original al finalizar la FA. Este efecto proarrítmico se cree debido al acortamiento de los peridodos refractarios auriculares inducido por la adenosina, disminuyendo la longitud de onda de los circuitos de reentrada y facilitando de este modo la coexistencia simultánea de varios frentes de activación en las aurículas como ocurre en la FA.Aunque es un fenómeno poco común, su reconocimiento es importante para evitar la administración repetida de dosis crecientes de adenosina, que podría llevar a la inducción de FA sostenida (AU)

[Ventricular arrhythmias induced by appropriate antibradycardia pacing in patients with implantable defibrillators]. / Inducción de arritmias ventriculares por estimulación antibradicardia apropiada en pacientes portadores de desfibrilador automático.

INTRODUCTION AND OBJECTIVES: The induction of ventricular arrhythmias by appropriate antibradycardia ventricular pacing in patients with implantable cardioverter defibrillators has been reported in only a few cases. The aim of this study was to assess the incidence, characteristics and management of these episodes. METHODS: The follow-up records of 180 patients with implantable cardioverter defibrillators with intracardiac electrogram storage were reviewed. Pacing induced episodes were defined as those occurring immediately after an appropriate paced stimulus in a patient with sporadic paced beats. We assessed the number and type of episodes, mode of onset, therapy administered and the efficacy of different prevention measures. RESULTS: Pacing induced episodes were found in 9 patients (5%). Seven received device administered therapy which was effective in all cases. One to 95 episodes were observed per patient, of which 138 were monomorphic ventricular tachycardias and 20 polymorphic ventricular tachycardia/ventricular fibrillation episodes. All were induced by a paced ventricular beat after a post-extrasystolic pause or after long RR intervals during atrial fibrillation. Pacing induced arrhythmias were prevented by changing the pacing rate or hysteresis in 3 out of 6 patients and by decreasing the stimulus energy in 3 out of 3. Antibradycardia pacing function was disabled in 4 patients. CONCLUSIONS: Ventricular arrhythmias induced by appropriate antibradycardia ventricular pacing are relatively common in patients with implantable cardioverter defibrillators. Effective prevention can be achieved in most cases by changing the pacing rate or the pacing stimulus energy, however in selected cases the antibradycardia function may be disabled.

Spontaneous sustained monomorphic ventricular tachycardia after administration of ajmaline in a patient with Brugada syndrome.

We present the case of a 13-year-old boy with an episode of aborted sudden death, absence of structural heart disease, and a characteristic ECG pattern of right bundle branch block with persistent ST-segment elevation in the right precordial leads, in whom a monomorphic sustained ventricular tachycardia developed spontaneously after the administration of ajmaline. This effect may be related to an increased inhomogeneity of repolarization mediated by the drug and demonstrates the arrhythmogenic potential of Class I antiarrhythmic drugs in patients with Brugada syndrome.

Modifications in the evolution of the dominant frequency in ventricular fibrillation induced by amiodarone, diltiazem, and flecainide. An experimental study.

In 22 anesthetized mongrel dogs, spectral methods were used to analyze the surface electrocardiogram (ECG) for the time course of the dominant frequency in ventricular fibrillation and its modifications under the influence of amiodarone, diltiazem, and flecainide. The ECG was recorded over 5 minutes after triggering ventricular fibrillation. Following A/D conversion and by applying the Fourier fast transform, the frequency spectrum of the signals was obtained. In group 1 (5 dogs), the ECGs were obtained without prior drug administration; group 2 (5 dogs) first received amiodarone, 5 mg/kg; group 3 (7 dogs) received diltiazem, 0.2 mg/kg; and group 4 (5 dogs) received flecainide, 2 mg/kg. All drugs were administered intravenously. An initial increase in the dominant frequency of ventricular fibrillation was found in the control group and also in the groups that received amiodarone, diltiazem, or flecainide. Diltiazem significantly increased the dominant frequency and diminished the arrhythmia-slowing process. Amiodarone and flecainide tended to diminish the dominant frequency.

Early and late exercise testing. Usefulness after percutaneous transluminal coronary angioplasty.

Seventy-five patients 36 to 68 years of age were studied after undergoing successful single-vessel percutaneous transluminal coronary angioplasty (PTCA). In all cases exercise tests (ETs) were made prior to the procedure and 2 to 4 days and 6 months thereafter. Angiographic controls were performed on patients with positive ET. Both early and late ET carried out after dilatation lasted significantly longer. Patients were able to tolerate greater work loads and their heart rates and arterial blood pressures also were higher. The ETs conducted prior to PTCA were positive in 62 patients. After dilatation, the early test was positive in 18 and the late test, in 10. Angiographic controls revealed restenosis in 75 percent of patients with single-vessel disease and positive ET. Thus, the results of ETs in patients with single-vessel disease tend to become negative after successful PTCA. Early and late positive ETs are associated with restenosis, while negative ETs indicate a good prognosis.

[Malignant vasovagal syncope: its diagnosis and therapeutic trial based on the orthostatism test (the tilt-table test)]. / Síncope vasovagal maligno: diagnóstico y ensayo terapéutico basado en el test de ortostatismo (test de TILT).

Seventy consecutive patients with recurrent unexplained syncope were evaluated by use of an up-right tilt-table test for 45 minutes (with or without an infusion of isoproterenol) in an attempt to reproduce symptoms. There were 42 males and 28 females with a mean age of 49 +/- 20 years (range 7-86), and with a mean symptoms duration of 35.2 +/- 16 months. All the patients underwent clinical examination which includes cardiological and neurological evaluation. Some tilt positive patients received therapy with either transdermal scopolamine, metoprolol or clonidine, the efficacy of which was evaluated by another tilt-table test. Syncope occurred in sixteen patients (22.9%), during the baseline tilt associated with hypotension (2 patients), bradycardia-asystolia (3 patients), or both (11 patients). In 11 patients with normal baseline tilt test, isoproterenol infusion was used appearing 4 new cases of abnormal response. Some patients who had positive test results, eventually became tilt-table negative by therapy (5 out of 8 patients treated with scopolamine, 5 out of 6 patients with metoprolol, and 3 out of 5 patients with clonidine). Time before syncope during tilt-test was increased with therapy, being of 45 min in normalized cases, and increasing from 11.9 +/- 16 basal to 34.4 +/- 17 min with scopolamine (p < 0.05), to 40 +/- 12 min with metoprolol (p < 0.05) and to 33.7 +/- 16.7 min with clonidine (p = NS). We conclude that upright tilt-table alone or combined with isoproterenol infusion is an useful test in the diagnosis of vasovagal syncope and in the evaluation of therapy.

[Hypertrophic myocardiopathy (II). 24-hour electrocardiographic monitoring and its relation to the echocardiographic characteristics]. / Miocardiopatía hipertrófica (II). Monitorización electrocardiográfica de 24 horas y su relación con las características ecocardiográficas.

Seventy-two patients with hypertrophic cardiomyopathy were evaluated by 24 hours of electrocardiographic ambulatory monitoring. The results were related to echocardiographic extent of hypertrophy, left ventricular outflow obstruction at rest, and transmitral flow parameters. Also, the symptoms and functional classification of NYHA were related to ventricular arrhythmias. Ventricular arrhythmias were detected in 68% of our patients: high degree of ventricular ectopia in 26 (36.1%), and ventricular tachycardia in 14 (19.4%). Most important supraventricular arrhythmias were: atrial fibrillation in 7 patients, atrial flutter in one, and supraventricular tachycardia in five. Asymmetric hypertrophy type I of Maron classification showed the lower number of ventricular arrhythmias. High degree of ventricular arrhythmias were more frequent in patients with: apical hypertrophy, worse functional classification of NYHA (I: 20%; II: 50%; III: 80%), and in patients with impaired distensibility detected by Doppler (80.7% vs 56.7%; p less than 0.05). There was no relationship between left ventricular outflow obstruction at rest and ventricular arrhythmias.