Influence of age, lead axis, frequency of arrhythmic episodes, and atrial dimensions on P wave triggered SAECG in patients with lone paroxysmal atrial fibrillation.

Signal-averaged P wave of 42 patients with lone paroxysmal atrial fibrillation (PAF) and 29 normal subjects (N) were recorded, using three orthogonal leads and analyzed in the time and frequency (entire P wave or a 100-ms segment ranging from 75 ms before to 25 ms after the end of P wave) domains. PAFs were divided into a group of 12 having > or = 2 attacks a month (HF) and a group of 30 having < or = 2 attacks a year (LF). Statistically significant differences were absent with regard to ages of PAF and N; ages of HF, LF, and N at the time of signal-averaged ECG; ages of HF and LF at the time of the first arrhythmic episode; and elapsed times from the first episode.

Wavelength index at three atrial sites in patients with paroxysmal atrial fibrillation.

The purpose of this study was to evaluate the wavelength index (WLI) at three atrial sites in a group of 23 patients with recurrent episodes of lone paroxysmal atrial fibrillation (LPAF) and a control group (n = 20). All patients underwent programmed atrial stimulation (paced cycle length = 600 ms) at high, medium, and low lateral right atrial wall. P wave duration, sinus cycle length, and corrected sinus node recovery time were not significantly different between the two study groups.

Plasma levels of natriuretic peptides during ventricular pacing in patients with a dual chamber pacemaker.

The mechanism(s) responsible for the release of brain natriuretic peptide (BNP), a cardiac hormone of ventricular origin, are still not completely understood. We measured plasma atrial natriuretic peptide (ANP) and BNP in 15 subjects (10 men, mean age 67 +/- 3 years) with a dual chamber pacemaker and unimpaired heart function during ventricular pacing, which is known to induce an increase in atrial pressure and plasma ANP concentration. Under ECG monitoring, all subjects received sequential atrioventricular pacing for 30 minutes and ventricular pacing for 30 minutes, at the same rate of 80 beats/min.

[Rational bases for the therapy of supraventricular tachycardias and their management].

Supraventricular arrhythmias are frequently encountered in clinical practice. Despite their common anatomical origin above the division of His' bundle into bundle branches, these arrhythmias have profoundly different electrophysiological mechanisms, clinical significances and responses to treatment. Although 12-lead surface ECG usually enables correct identification, facilitating treatment choice in the emergency room, electrophysiologic testing to determine the site of origin and the pathway of the arrhythmia may be necessary for the management of definitive treatment.

[Arrhythmogenicity in left ventricular hypertrophy in mild to moderate arterial hypertension].

Background: Several studies have evidenced that hypertensive patients (pts) with left ventricular hypertrophy (LVH) have an increased incidence of malignant ventricular arrhythmias and sudden death. The purpose of our study was to investigate the prevalence of risky ventricular arrhythmias in uncomplicated hypertensive pts (untreated during last 10 days) in comparison with normotensive ones. In this context, not only the value of left ventricular mass index (LVMI) was taken into account, but also the type of LVH and the related functional behaviour.

Effect of right atrial stimulation on both atrial pressure and atrial natriuretic peptide release in essential hypertension.

Unlabelled: Several reports indicated a direct relationship between atrial pacing and atrial natriuretic peptide (ANP) blood levels, but few controlled hemodynamic studies have been reported. In particular, the relationship between increase in heart rate, release of ANP and increase in right atrial pressure (RAP) are still uncertain. Moreover, the effect of accelerated heart rate on ANP secretion in patients with essential hypertension has not yet been fully elucidated.

Effects of training on the electrophysiologic properties of atrium and accessory pathway in athletes with Wolff-Parkinson-White syndrome.

Twenty-two subjects with Wolff-Parkinson-White (WPW) electrocardiographic pattern performing agonistic physical activity were referred to our laboratory to assess arrhythmogenic risk (group 1). This allowed us to evaluate a less known aspect, namely that of effects of training on the electrophysiologic properties of the atrium and accessory pathway. This was done utilizing a control group of 10 WPW patients who did not perform agonistic physical activity (group 2).

[Atrial electrophysiologic properties in paroxysmal atrial fibrillation. Study conducted with the stimulation of 5 atrial sites].

Programmed atrial stimulation at five atrial sites was performed to evaluate electrophysiologic atrial properties in 17 control patients (14 M, 3F, mean age 61 +/- 9 years) (Group A) and in 18 patients with paroxysmal atrial fibrillation (13 M, 5 F, mean age 61 +/- 5 years) (Group B) with normal sinus node function. The mean value of the P wave duration was similar in both groups. Programmed atrial stimulation was performed at five atrial sites: high, medium and low lateral wall, and high and low medial wall.

Relationship between age and anterograde refractoriness of the accessory pathway in Wolff-Parkinson-White patients.

In 22 patients (age range 13-40 years) with Wolff-Parkinson-White ECG pattern without evidence of associated cardiomyopathy we measured the anterograde effective refractory period of the accessory pathway (ERP-AP) by extrastimulus method (at twice diastolic threshold) during atrial pacing (100/min). The ERP-AP range was 220-480 ms. There was a significant direct correlation between age and ERP-AP (r = 0.

Effects of propafenone on directly measured sinoatrial conduction time.

Electrophysiologic investigation of the effects of antiarrhythmic drugs on sinoatrial conduction time (SACT) is conditioned by the inadequacies of indirect methods employing premature or asynchronous atrial stimulation. Direct recording of sinus node electrogram (SNE) is unaffected by the limitations of the indirect methods and is particularly useful when the effect of a drug on SACT is to be studied. In the present study the effect of propafenone on SACT directly (D) measured from SNE in 12 patients (7 male and 5 female subjects, 61 +/- 10 years) with normal sinus node function (NSNF) was investigated.

Atrial electrophysiologic properties of patients with asymptomatic Wolff-Parkinson-White syndrome.

To evaluate the existence of a peculiar atrial electrophysiologic substrate, we studied 18 patients with asymptomatic Wolff-Parkinson-White (WPW) syndrome. These patients were compared with 10 age-matched normal subjects (N). Effective and functional refractory periods were determined at two right atrial sites (high and low in the lateral wall), during atrial pacing (100 min-1) and at twice diastolic threshold.

Influence of current strength on excitability and conduction of human atrium and atrioventricular node.

The influence of current strength on excitability and conduction of atrium and atrioventricular node was assessed in 25 patients using different current strengths (2, 3, 4, 5, 7, 10, 15 mA) and introducing extrastimuli (parasinusal zone) after the eighth paced complex of a basic drive (100 beats X min-1). Bipolar stimulation with the distal pole as cathode was performed so that effective and functional refractoriness of atrium and atrioventricular node, and the maximum value of atrial latency (interval between the extrastimulus and the beginning of atrial activity), intra-atrial conduction time, and AH interval could be determined at each current strength. In some patients atrioventricular nodal effective refractoriness could or could not be determined at each current strength, whereas in others the determination was possible only at the highest or the lowest current strengths.

Effects of pharmacologic autonomic blockade on atrial electrophysiologic properties in normal subjects and in patients with sinus node disease.

In order to elucidate the influence of autonomic nervous system on atrial electrophysiologic properties, we studied 10 patients with sinus node dysfunction and 10 age-matched normal subjects. In each of them effective and functional refractory periods of the right atrium (near its junction with the superior caval vein) were measured, during atrial pacing (100/min) and using variable current strengths (2, 3, 4, 5, 7, 10, and 15 mA), before and after pharmacologic autonomic blockade (using intravenous propranolol 0.2 mg/kg and atropine 0.

Anterograde sinuatrial conduction evaluated by sinus node electrogram in atropine blocked retrograde atrial conduction.

Two cases are described where atropine induced the disappearance of reset zone as response to premature atrial stimulation for blocked retrograde atrial conduction. Because of this, sinuatrial conduction time could not be estimated. The sinus node electrogram allowed the direct measurement of sinuatrial conduction and showed a facilitated anterograde conduction through the perinodal fibers after administration of the drug.

Clinical electrophysiological effects of chronic administration of verapamil: the phenomenon of overdrive excitation of junctional pacemaker.

The electrophysiological effects of chronic administration of verapamil were studied in 10 patients with normal sinus node function, who received 160 mg of the drug every eight hours for at least two weeks. Uncorrected and corrected sinus node recovery time, sino-atrial conduction time, effective and functional refractory periods were normal in each case. In three patients, at the cessation of atrial pacing, an overdrive excitation of junctional pacemaker with short lasting A-V dissociation was observed.

Effects of atropine on atrial refractoriness and its dispersion in humans.

To evaluate the influence of atropine on atrial refractoriness and its dispersion, we studied ten subjects with sinus bradycardia who were otherwise healthy. Effective and functional refractory periods were measured at three sites of the right atrium (high, middle, and low in the lateral wall), in sinus rhythm and during atrial pacing (120/min), before and after i.v.

[Comparison of Narula's technic of direct and estimated sinoatrial conduction at increasing rates in normal subjects].

Twenty eight normal subjects in sinus rhythm underwent direct measurement of sinoatrial conduction time (SACTD) by sinus node potential recordings (SNP) and indirect evaluation by Strauss (SACTS) and Narula's methods (SACTN) using the extrastimulus technique. Stimulation in Narula's method was undertaken at three different rates, 3, 6 and 9 beats per minute faster than the spontaneous rate of the subject (SACTN3, SACTN6, SACTN9). The mean values (+/- SD) were as follows: SACTD 84 +/- 18, SACTN3 85 +/- 29, SACTN6 96 +/- 33, SACTN9 101 +/- 36.

The effects of atropine on sinoatrial conduction time directly measured from sinus node electrogram. A comparison with results furnished by indirect methods.

The effects of atropine on sinoatrial conduction time (SACT) measured directly (SACTD) from the sinus node electrogram (SNE) were investigated in 15 patients with normal sinus node function. A comparison was undertaken with the results furnished by indirect methods which employ premature (SACTS) and asynchronous atrial stimulation (SACTN) to calculate SACT. In the control state SACTD was 92.

Aging and atrial electrophysiologic properties in man.

In order to assess the influence of age on atrial electrophysiologic properties, we studied 17 normal subjects, whose ages were homogeneously distributed between 17 and 78 years, measuring in each of them effective (ERP) and functional (FRP) refractory periods at 3 sites of the right atrium (high, middle and low in the lateral wall) at the same driven frequency (120/min). Twice threshold stimuli of 2 msec duration were applied. Dispersion of atrial refractoriness was measured as the longest minus the shortest refractory period.

An unusual PR interval alternans during 2:1 atrio-ventricular block.

In a case of a 2:1 second degree A-V block during sinus rhythm, PR intervals of two different durations occur, either separately or alternating beat-by-beat. The longer intervals are not caused by concealed conduction in the A-V junction of the preceding blocked impulses and the shorter ones are not due to supernormal conduction induced by the blocked impulses. This primary PR interval alternans is alternating from a pathophysiological point of view; it only concerns every other impulse alternately traveling along the faster and slower A-V junctional pathway.

Cardiac effects of clomipramine treatment. ECG and left ventricular systolic time intervals.

ECGs and left ventricular systolic time intervals were studied in 26 patients suffering from major depressive disorder treated with clomipramine. ECGs did not show, with one exception, drug-induced changes. The ratio of pre-ejection period to left ventricular ejection time, both corrected for heart rate (PEPc/LVETc), presented no significant changes, as compared with initial findings, in the group of patients considered as a whole.