BACKGROUND Inappropriate sinus tachycardia (IST) and postural tachycardia syndrome (POTS) are 2 disorders characterized by sinus tachycardia. It is debated whether the pathophysiology of IST and POTS results from abnormal autonomic regulation or abnormal sinus node function. We hypothesized that intrinsic heart rate (IHR) after autonomic blockade would be increased in patients with IST but not ...

One-to-two atrioventricular conduction, ie, the double response to a single sinus or atrial impulse, resulting in two QRS complexes for one P wave, is a rare manifestation of dual atrioventricular (AV) nodal pathways. This report describes the case of a 61-year-old woman with continuous episodes of supraventricular tachycardia caused by independent conduction to the ventricles of sinus impulses...

BACKGROUND Syncope in patients with supraventricular tachycardia has been suggested to be an ominous finding, predictive of rapid rates during tachycardia. METHODS AND RESULTS To explore the mechanism of syncope during supraventricular tachycardia, tachycardia was induced in the supine position and after passive head-up tilting to 60 degrees in 13 patients with atrioventricular (AV) node reen...

In 35 patients aged 18 to 69 years (mean 48) with clinical, electrocardiographic, or electrophysiological evidence of normal sinus node function, the effect of intravenous propranolol (0.1 mg/kg) was assessed on 3 indices of sinus node function. The drug significantly prolonged sinus node cycle length (12%), slightly prolonged the corrected sinus node recovery time (15%), and slightly but insig...

BACKGROUND Radiofrequency ablation (RFA) for atrioventricular nodal reentrant tachycardia appears to reduce atrial tachycardia, which might relate to parasympathetic denervation at cardiac ganglionated plexuses. METHODS AND RESULTS Compared to 7 control canines without RFA, in 14 canines, RFA at the bottom of Koch's triangle attenuated vagal stimulation-induced effective refractory periods pr...

A 49-year-old male was referred for catheter ablation for paroxysmal atrial fibrillation (PAF). PAF had recurred after each of 2 prior left atrial ablation procedures. He had a structurally normal heart with a left atrial diameter of 43 mm. The patient presented to the electrophysiology laboratory in AF with an average AF cycle length (CL) of 150 ms and reconnected pulmonary veins. After electr...

A 49-year-old male was referred for catheter ablation for paroxysmal atrial fibrillation (PAF). PAF had recurred after each of 2 prior left atrial ablation procedures. He had a structurally normal heart with a left atrial diameter of 43 mm. The patient presented to the electrophysiology laboratory in AF with an average AF cycle length (CL) of 150 ms and reconnected pulmonary veins. After electr...

INTRODUCTION The aim of this study was to evaluate the changes in ventricular complex voltage associated with narrow QRS supraventricular tachycardia (SVT). METHODS AND RESULTS One hundred forty-five patients undergoing catheter ablation for SVT, 85 with AV nodal reentrant tachycardia (AVNRT) and 60 with AV reentrant tachycardia (AVRT) due to a concealed accessory pathway, were studied. Four ...

Inappropriate sinus tachycardia (IST) is a syndrome characterized by unexplained tachycardia (heart rate > 100 beats /min) and related symptoms at rest. We describe a case of a 35 year old male with end stage renal disease who developed IST after renal transplant in the surgical intensive care unit. Management of IST is usually nonspecific and includes bradycardic agents, radiofrequency ablatio...

A 20-year-old woman underwent an electrophysiological study for drug-resistant persistent inappropriate sinus tachycardia (IST). Use of a high-dose continuous intravenous administration of landiolol, a short-acting beta-adrenoreceptor blocker, made the patient׳s heart rate suddenly drop with a slight change in the P-wave morphology. Three-dimensional right atrial (RA) activation mapping reveale...