Part II-Clinical presentation, electrophysiologic characteristics, and when and how to ablate atriofascicular pathways and long and short decrementally conducting accessory pathways.

Recognition of the presence, location, and properties of unusual accessory pathways for atrioventricular conduction is an exciting, frequently difficult, challenge for the clinical cardiac arrhythmologist. In this second part of our series of reviews relative to this topic, we discuss the steps required to achieve the correct diagnosis and appropriate management in patients with the so-called "Mahaim" variants of pre-excitation. We indicate that, nowadays, it is recognized that these abnormal rhythms are manifest because of the presence of atriofascicular pathways.

When and how does a single ventricular premature beat initiate and terminate supraventricular tachycardia?

Background: The differential diagnosis of a supraventricular tachycardia (SVT) is accomplished using a number of pacing maneuvers. The incidence and mechanism of a single ventricular premature beat (VPB) on initiation and termination of tachycardia were evaluated during programmed electrical stimulation (PES) of the heart in patients with the two most common regular SVTs: atrioventricular re-entrant tachycardia (AVNRT) and orthodromic atrioventricular tachycardia (AVRT).

Methods: Three hundred and thirty-seven consecutive patients aged above 18 years with an inducible sustained AVNRT or AVRT were prospectively enrolled.

Short QT syndrome in pediatrics.

Short QT syndrome is a malignant cardiac disease characterized by the presence of ventricular tachyarrhythmias leading to syncope and sudden cardiac death. Currently, international guidelines establish diagnostic criteria when QTc is below 340 ms. This entity is one of the main diseases responsible for sudden cardiac death in the pediatric population.

Surgical treatment of atrial fibrillation using bipolar radiofrequency ablation in rheumatic mitral disease.

Objective: To analyze the effectiveness of surgical treatment of atrial fibrillation (AF) using bipolar radiofrequency ablation during mitral valve procedures of rheumatic etiology in heart surgery.

Methods: We retrospectively reviewed medical registries of 53 patients submitted to atrial ablation with bipolar radiofrequency energy during mitral valve surgery. Thirty four (64%) patients were women and the age varied from 27 to 72 years old (average: 49.

Use of bipolar radiofrequency for the treatment of atrial fibrillation during cardiac surgery.

Background: Atrial fibrillation with tissue ablation device through bipolar radiofrequency in conjunction with cardiac surgery has proven to be an effective method to treat this arrhythmia.

Objective: Describe the initial experience of the Instituto Nacional de Cardiologia in the surgical treatment of atrial fibrillation using bipolar radiofrequency device in patients undergoing cardiac surgery, reporting the results of postoperative follow-up of one year.

Methods: Between January 2008 and March 2009, 47 consecutive patients (36 women), with mean age of 53.

Videothoracoscopy for isolated atrial fibrillation ablation through bipolar radiofrequency.

Background: The prevalence of atrial fibrillation, expenses with the healthcare system and the associated high morbidity and mortality have justified the search for new therapeutic approaches.

Objective: To evaluate the reproducibility of the surgical technique, its safety and the initial outcome of the video-assisted surgery for the isolated atrial fibrillation ablation with bipolar radiofrequency.

Methods: Ten patients (90% men) with symptomatic atrial fibrillation (50% paroxystic type) that was refractory to drug therapy, with no heart disease that required concomitant surgical treatment, were submitted to arrhythmia ablation guided by thoracoscopy from May 2007 to May 2008.

Catecholaminergic polymorphic ventricular tachycardia: a current overview.

Catecholaminergic polymorphic ventricular tachycardia occurs in healthy children and young adults causing syncope and sudden cardiac death. This is a familial disease, which affect de novo mutation in 50% of the cases. At least two causative genes have been described to be localized in the chromosome 1; mutation of the ryanodine receptor gene and calsequestrin gene.

Contribution of the electrophysiological and anatomical analysis of the atypical atrioventricular nodal tachycardia circuit.

Objectives: To analyze retrograde conduction during junctional ectopic tachycardia (JET) episodes and investigate the existence of a relationship between the presence of a retrograde block and the risk of atrioventricular block (AVB) development during radiofrequency ablation procedures in patients with nodal atrioventricular tachycardia (NAVT).

Methods: 145 male and female patients aged 16-84 years, with NAVT who had undergone radiofrequency catheter ablation in the posteroseptal region of the right atrium were studied. Evaluation criteria were anatomical location and electrophysiological behavior of retrograde conduction during NAVT, in order to understand the nodal reentrant circuit (classifying the tachycardia as typical or atypical), and monitoring of retrograde conduction during JET episodes for risk-predicting AVB events.

Automaticity in Mahaim fibers.

Introduction: Automatic rhythms associated with Mahaim fibers usually occur during radiofrequency catheter ablation. The incidence and significance of spontaneous automaticity in Mahaim fibers are unknown.

Methods And Results: Spontaneous automatic rhythms were observed in 5 (12.

Improvement in left ventricular dysfunction after surgical correction of mitral regurgitation.

Objective: To evaluate whether left ventricular end-systolic (ESD) diameters < or = 51mm in patients (pt) with severe chronic mitral regurgitation (MR) are predictors of a poor prognosis after mitral valve surgery (MVS).

Methods: Eleven pt (aged 36 +/- 13 years) were studied in the preoperative period (pre), median of 36 days; in the early postoperative period (post1), median of 9 days; and in the late postoperative period (post2), mean of 38.5 +/- 37.

Clinical and molecular characterization of patients with catecholaminergic polymorphic ventricular tachycardia.

Background: Mutations in the cardiac ryanodine receptor gene (RyR2) underlie catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited arrhythmogenic disease occurring in the structurally intact heart. The proportion of patients with CPVT carrying RyR2 mutations is unknown, and the clinical features of RyR2-CPVT as compared with nongenotyped CPVT are undefined.

Methods And Results: Patients with documented polymorphic ventricular arrhythmias occurring during physical or emotional stress with a normal heart entered the study.