Claudio Meirelles Medeiros

Intrinsic sinus and atrioventricular node electrophysiologic adaptations in endurance athletes.

OBJECTIVES In the present study, we evaluated sinus and atrioventricular (AV) node electrophysiology of endurance athletes and untrained individuals before and after autonomic pharmacologic blockade. BACKGROUND Endurance athletes present a higher prevalence of sinus bradycardia and AV conduction abnormalities, as compared with untrained individuals. Previous data from our laboratory suggest that nonautonomic factors may be responsible for the longer AV node refractory period found in well-trained athletes. METHODS Six aerobically trained male athletes and six healthy male individuals with similar ages and normal rest electrocardiograms were studied. Maximal oxygen uptake (O(2)max) was measured by cardiopulmonary testing. The sinus cycle length (SCL), AV conduction intervals, sinus node recovery time (SNRT), Wenckebach cycle (WC) and anterograde effective refractory period (ERP) of the AV node were evaluated by invasive electrophysiologic studies at baseline, after intravenous atropine (0.04 mg/kg) and after addition of intravenous propranolol (0.2 mg/kg). RESULTS Athletes had a significantly higher O(2)max as compared with untrained individuals. The SCL was longer in athletes at baseline, after atropine and after the addition of propranolol for double-autonomic blockade. The mean maximal SNRT/SCL was longer in athletes after atropine and after propranolol. The WC and anterograde ERP of the AV node were longer in athletes at baseline, after atropine and after propranolol. CONCLUSIONS Under double-pharmacologic blockade, we demonstrated that sinus automaticity and AV node conduction changes of endurance athletes are related to intrinsic physiology and not to autonomic influences.

Randomized study of propofol effect on electrophysiological properties of the atrioventricular node in patients with nodal reentrant tachycardia.

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is probably the most common form of paroxysmal supraventricular tachycardia. Percutaneous catheter ablation is a technique to interrupt cardiac conduction pathways selectively. The anesthetist is challenged to provide a safe anesthetic which takes into account the electrophysiologists requirements for minimal cardiac conduction interference. Propofol is an ideal drug. However, previous studies have shown that the infusion of propofol has sometimes been associated with bradyarrhythmias or conversion of arrhythmias to sinusal rhythm. The purpose of this report is to verify the interferences of propofol in the electrophysiological properties of the atrioventricular (AV) node conduction system in patients with AVNRT.

Alternate Wenckebach conduction through the right bundle branch

This case report describes a patient with chronic chagasic myocarditis who presented with a unique tachycardia-dependent or phase 3 aberrant ventricular conduction. The electrocardiogram showed sinus tachycardia with sequences of alternate and progressive right bundle branch block, that is, Wenckebach periods of alternate beats. We postulated the existence of functional longitudinal dissociation in atrioventricular conduction axis, responsible for the alternant normal and Wenckebach beats.

Catheter-induced 3:1 second degree atrioventricular nodal block during atrioventricular nodal reentrant tachycardia

Second-degree atrioventricular (AV) nodal block with 2:1 AV conduction during atrioventricular nodal reentrant tachycardia (AVNRT) has been previously described. We report a patient who developed AVNRT during which 3:1 intra-infra-Hisian block due to catheter manipulation was observed. This was followed by gradual, incremental recovery of AV conduction. AVNRT accounts for approximately 50% of cases of supraventricular tachycardia. This mechanism of tachycardia uses a reentrant circuit in the region of the AV Node which usually contains distinct slow and fast pathways. Radiofrequency ablation of the slow pathway is an effective and safe treatment for AVNRT . In this report, we present a patient with AVNRT of the common type who developed 3:1 intra-infra-Hisian block during AVNRT as a result of catheter manipulation. Before resumption of normal 1:1 conduction, we observed split His potentials in normal sinus rhythm, followed by atrioventricular (AV) nodal echo beats with intra-infra-Hisian block.

Parecer da Comissão Técnica designada pelo Departamento de Arritmias e Eletrofisiologia Clínica da Sociedade Brasileira de Cardiologia (DAEC/SBC)

4 5 7 Correspondencia: Fernando E. S. Cruz Fo Rua Ipu, 32 22281-040 Rio de Janeiro, RJ Fernando E. S. Cruz Fo (Coordenador), Adalberto Lorga, Angelo A. V. de Paola, Ayrton K. Peres, Cidio Halperin, Claudio Medeiros, Eduardo B. Sternick, Eduardo Sosa, Jacob Atie, Marcio L. A Fagundes, Reynaldo de Castro Miranda, Sergio Rassi Parecer da Comissao Tecnica Designada pelo Departamento de Arritmias e Eletrofisiologia Clinica da Sociedade Brasileira de Cardiologia (DAEC/SBC) Parecer tecnico DAEC/SBC

Registradores de eventos. Uma alternativa para esclarecimento de sintomas de provável origem cardíaca

187 Laboratorio de Cardiologia Diagnostika, Hospital Moinhos de Vento, Cardioritmo e Servico de Cardiologia, Hospital de Clinicas de Porto Alegre, Faculdade de Medicina UFRGS Porto Alegre Correspondencia: Leandro I. Zimerman Rua Ramiro Barcelos 910 cj. 702 90035001 Porto Alegre, RS Recebido para publicacao em 21/10/97 Aceito em 7/1/98 Leandro Ioschpe Zimerman, Claudio Meirelles Medeiros, Jorge Pinto Ribeiro

Atrioventricular junctional and orthodromic atrioventricular reentrant tachycardia in Wolff-Parkinson-White syndrome.

The existence of two or more types of reentrant tachycardias in the same patient with Wolff-Parkinson-White syndrome has been emphasized, and the occurrence of orthodromic atrioventricular (AV) reentrant tachycardia and AV junctional reentrant tachycardia have been well documented. This report describes a patient with Wolff-Parkinson-White syndrome in whom the phenomena of spontaneous transition from AV reentry to AV junctional reentry and adenosine-induced conversion from AV junctional reentry to AV reentry were observed.