A 29-year-old woman underwent an electrophysiologic procedure because of a 10-year history of recurrent episodes of paroxysmal supraventricular tachycardia. The baseline cycle length, atrial-His (AH), and His-ventricular (HV) intervals were 550, 50, and 45 msec, respectively. The AV block cycle length was 270 msec. With programmed atrial stimulation, there was no evidence of dual AV nodal pathw...

Three patients with the Wolff-Parkinson-White (WPW) syndrome were studied using His bundle recordings and programmed atrial stimulation. In two of them conduction of premature atrial depolarizations via the accessory pathway was possible when the His-Purkinje system was still refractory. The consequent conduction delay in the His-Purkinje system resulted in re-entry phenomena at the ventricular...

Electrophysiologic studies were performed in a patient who had an apparently uncomplicated complete trifascicular block. His bundle recordings revealed atrioventricular dissociation with: 1) an atrial rate of 58 beats/min, 2) an idioventricular escape rate of 45 beats/min, and 3) nonparoxysmal junctional tachycardia (His bundle rhythm) at a rate of 65--85 beats/min. The latter arrhythmia was el...

Supraventricular tachycardia in an isolated rabbit heart preparation was repeatedly initiated and terminated by carefully timed atrial premature beats. Transmembrane action potentials of AV nodal cells were recorded simultaneously by a "brush electrode" consisting of 10 microelectrodes. Surface electrograms of atrium and His bundle were also recorded. The moments of activation of 54 different A...

BACKGROUND Pulmonary veins (PVs) are important sources of paroxysmal atrial fibrillation. Long-term rapid atrial pacing (RAP) changes atrial electrophysiology and facilitates the maintenance of atrial fibrillation. It is not clear whether RAP alters the arrhythmogenic activity of PVs. The purpose of this study was to isolate single PV cardiomyocytes from control and RAP dogs and evaluate their ...

The hemodynamic consequences of cardiac arrhythmias depend on various factors, including the ventricular rate and the duration of the abnormal rate, the temporal relationship between atrial and ventricular activity, the sequence of ventricular activation, the functional state of the heart, the irregularity of the cycle length, associated drug therapy, the peripheral vascular vasomotor system, d...

OBJECTIVE To study the antiarrhythmic effect of remifentanil in experimental arrhythmias in dogs. METHODS We used dogs weighing 12 kg-18 kg anesthetized with 30 mg/kg sodium pentobarbital given intravenously. Ventricular arrhythmia, ventricular fibrillation and death were induced with digoxin (9 microg/kg/min). In another model, two types of arrhythmia were induced in the right atrium, one of...

The structure of atrial natriurtic peptide (ANP) and Brain natriuretic peptide (BNP) are similar and they are also similar in their actions e.g natriuresis and vasodilation. The previous studies have revealed the presence of ANP and BNP in sheep atrial extract, wherease ANP in human atrial. The aim of the present study is to investigate the comparison of hemodynamic effects of these two atrial ...