Search PubMed⌕ Search

Biomedical subjects

A Arenal

Publications and source records attributed to A Arenal.

At least 37 records · Page 2Linked to original sources
PubMed1995

Evidence favoring the hypothesis that ventricular arrhythmias have prognostic significance in left ventricular hypertrophy secondary to systemic hypertension.

In the present review 6 lines of evidence will be discussed that suggest a prognostic significance for ventricular arrhythmias in patients with systemic hypertension and left ventricular hypertrophy: (1) in patients with systemic hypertension there is a statistical relation between asymptomatic ventricular arrhythmias and left ventricular hypertrophy; (2) in nonhypertensive left ventricular hypertrophy the prognostic value of ventricular arrhythmias is well known; (3) left ventricular hypertrophy is related to sudden death in patients with systemic hypertension; (4) it is generally acknowledged that ventricular arrhythmias are a frequent cause of sudden death; (5) there is experimental evidence to support the arrhythmic risk of left ventricular hypertrophy; and (6) it has been recently demonstrated that ventricular arrhythmias influence mortality in patients with left ventricular hypertrophy secondary to systemic hypertension. However, whether asymptomatic ventricular arrhythmias are specific markers for more severe sustained arrhythmias, or just markers for a more severe stage of the disease, remains to be determined.

Arrhythmias, Cardiac↗
PubMed1995

The Cantabria first episode schizophrenia study: a summary of general findings.

This article describes the general findings of the initial cross-sectional stage of a prospective follow-up study of all first episodes of schizophrenia that occurred in the Autonomous Community of Cantabria over a 2-year period and that established contact with any mental health service. The project comprises: i) a 2-year cross-sectional stage, in which the sample was gathered and studied with structured psychiatric instruments such as the Present State Examination and the Scales for the Assessment of Negative and Positive Symptoms (SANS and SAPS), and; ii) a continuous follow-up. We detected, in the risk age ranged of 15-54 years, an incidence of 1.9 per 10,000 inhabitants per year for schizophrenia and of 1.3 per 10,000 inhabitants per year for the S+ CATEGO diagnosis, without any significant gender difference of morbidity. The mean age for the total schizophrenic population was 26 years, being significantly higher in women than in men. In contrast with what happens with marital status, type of household or urban/rural way of life, there was no gender difference in relation to the other sociodemographic variables. The way in which nosological and clinical variables are associated with first episodes of schizophrenia was also examined in this study. We found that 75% of patients reached a maximum CATEGO-ID level, 71% received a S+ CATEGO diagnosis, 59% presented first-rank symptoms of schizophrenia and that the percentage of a schizophrenic negative syndrome, as identified by the SANS and SAPS, was very low.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

[Radiofrequency ablation of a posteroseptal accessory pathway associated with coronary sinus diverticulum].

The case of a patient with a symptomatic Wolff-Parkinson-White syndrome undergoing attempted radiofrequency catheter ablation of a posteroseptal accessory pathway is described. Coronary sinus venography revealed the presence of a diverticulum attaching near the os. The electrogram recorded from a catheter placed in the narrow neck of the diverticulum revealed a short atrioventricular time during sinus rhythm. The pathway was easily ablated using radiofrequency energy applied in the neck of the diverticulum, after multiple failed attempts at catheter ablation from the endocardial surface of the posteroseptal space. Our report emphasizes the importance of searching for a coronary venous diverticulum in all patients with posterior accessory pathways undergoing catheter ablation.

Adult↗
PubMed1994

Identification of concealed posteroseptal Kent pathways by comparison of ventriculoatrial intervals from apical and posterobasal right ventricular sites.

BACKGROUND: The differential diagnosis of supraventricular tachycardia with concentric atrial activation usually requires the inducibility of sustained tachycardia and needs a complex and time-consuming electrophysiological evaluation. To develop a simple test to establish if ventriculoatrial conduction uses a posteroseptal accessory pathway or the normal conduction system, we compared the ventriculoatrial intervals during right ventricular pacing from apical and posterobasal sites. METHODS AND RESULTS: Continuous pacing was performed from an apical and a posterobasal right ventricular site in 34 patients with retrograde conduction over the normal conduction system (group A) and in 22 patients with conduction over a posteroseptal accessory pathway (group B). During apical pacing, ventriculoatrial intervals in group A (176 +/- 40 milliseconds) were not significantly different than those in group B (197 +/- 47 milliseconds, P = NS). During posterobasal pacing, group B patients had significantly shorter ventriculoatrial intervals than group A patients (158 +/- 46 versus 197 +/- 39 milliseconds, P < .01). The difference between the ventriculoatrial interval obtained during apical pacing and that obtained during posterobasal pacing (ventriculoatrial index) discriminated between the two groups without overlapping: It was positive in all group B patients (39 +/- 19; range, +10 to +70 milliseconds) and negative in all except two group A patients (-21 +/- 13; range, -50 to +5 milliseconds; P < .001). CONCLUSIONS: This ventriculoatrial index can identify accurately and in the absence of tachycardia whether concentric retrograde conduction is proceeding over a posteroseptal accessory pathway or over the normal conduction system.

Adult↗
PubMed1993

Comparison of electrophysiologic effects of quinidine and amiodarone in sustained ventricular tachyarrhythmias associated with coronary artery disease.

Fifteen patients with spontaneous ventricular tachyarrhythmias underwent electrophysiologic studies at baseline and during therapy with quinidine and amiodarone. In 9, ventricular tachycardia (VT) with a similar QRS morphology was induced with quinidine, amiodarone and under the control state. Both quinidine and amiodarone significantly increased QRS duration and the VT cycle length. Amiodarone increased the VT cycle length more than quinidine (85 vs 121 ms, p < 0.05). Amiodarone increased the percent QRS duration (during sinus rhythm, ventricular pacing and VT) significantly less than percent VT cycle length, whereas quinidine did so only at slow rates (at faster rates the percent increase in QRS duration is not different from the percent increase in VT cycle length). The percent increase in QRS duration produced by quinidine correlated significantly with the percent increase in VT cycle length (the best correlation was observed during pacing, r = 0.78). In contrast, no such significant correlations were obtained for amiodarone. Thus, amiodarone prolongs VT cycle length more than quinidine (at the doses used). The effects of quinidine on conduction in tissue mostly unrelated to tachycardia origin predict effects in the tachycardia cycle length. In contrast, the effects of amiodarone on the latter are more intense but not predicted by those on tissue unrelated to the tachycardia origin.

Adult↗
PubMed1993

The importance of antitachycardia pacing for patients presenting with ventricular tachycardia.

The initial experience from electrophysiological studies showed that pacing induced termination of ventricular tachycardias is usually possible but requires a critical pacing sequence. Studies on the resetting phenomenon showed, in most instances of failure of termination, that the "limiting factor" to produce ventricular tachycardia termination is usually failure to produce block within the circuit rather than failure to access or interact with the ventricular tachycardia origin. The resetting response is related to tachycardia termination in a number of ways. Of note is that a steeply increasing resetting pattern usually predicts tachycardia termination. Between 50% and 90% of induced ventricular tachycardias will be terminated by trains of rapid ventricular pacing. The analysis of the pacing rate necessary for termination shows that it varies widely. Paced cycle lengths of < 80% of tachycardia cycle length are necessary in at least 20% of tachycardias. In contrast, the incidence of acceleration is closely related to the paced cycle length: it is negligible with paced cycle lengths over 80% of tachycardia cycle length and increases to 36% with paced cycle lengths below 76% of tachycardia cycle length. Present information about efficacy of antitachycardia pacing in spontaneous tachycardias suggests that it is extremely effective, with over 90% success. However, it is likely that these data correspond to a selected group of tachycardias.

Cardiac Pacing, Artificial↗
PubMed1993

Mechanism of selective epicardial activation delay during acute myocardial ischemia in dogs.

BACKGROUND: Previous studies have shown that acute myocardial ischemia in the dog results in much greater activation delays in epicardial than endocardial tissue. These results have been interpreted to indicate enhanced sensitivity of epicardial conduction properties to acute ischemia. This study was designed to test the hypothesis that the ischemic epicardial activation delay during supraventricular rhythms is due to slow conduction across the ischemic myocardial wall prior to epicardial activation and not to enhanced epicardial conduction slowing per se. METHODS AND RESULTS: Changes in epicardial and endocardial activation were measured with transmural decapolar needle electrodes during successive 5-minute left anterior descending coronary artery (LAD) occlusions separated by 30-minute reperfusion periods. Occlusions were performed during left atrial pacing, right ventricular pacing with a stimulating electrode located along the longitudinal axis of epicardial fiber orientation in the ischemic zone, or left ventricular pacing in nonischemic tissue located on a line transverse to fiber orientation in the ischemic zone. During both atrial and left ventricular pacing, activation in the ischemic zone began in the endocardium. Epicardial activation resulted from transmural conduction and was markedly delayed compared with endocardial activation during acute myocardial ischemia. During right ventricular stimulation, the ischemic zone epicardium was activated via longitudinal epicardial conduction, and its activation was only slightly delayed by acute ischemia. Epicardial activation mapping was used to assess ischemia-induced changes in longitudinal epicardial conduction velocity and to compare them with changes in transmural velocity during atrial or left ventricular pacing. Longitudinal conduction in the ischemic epicardium was slowed by 13 +/- 4% (mean +/- SE) relative to preischemic control values in contrast to transmural conduction, which was slowed 50 +/- 4% by LAD occlusion during atrial pacing and 49 +/- 5% during left ventricular pacing (both P < .001 versus longitudinal epicardial conduction). Transmural activation studies showed that the midmyocardium is the site of most of the ischemic activation delay during transmural propagation. CONCLUSIONS: Epicardial activation is more delayed than endocardial by acute ischemia during supraventricular rhythms in dogs because of slowed conduction across the myocardial wall, not because of enhanced sensitivity of epicardial conduction to depression by acute ischemia.

Acute Disease↗
PubMed1993

Ventricular fusion during resetting and entrainment of orthodromic supraventricular tachycardia involving septal accessory pathways. Implications for the differential diagnosis with atrioventricular nodal reentry.

BACKGROUND: Ventricular fusion during transient entrainment of orthodromic atrioventricular reciprocating tachycardias (OAVRT) was originally found to be absent and recently observed only with left ventricular stimulation. However, previous studies were restricted to cases with a left free wall accessory pathway. The hypothesis of the present study was that fusion is likely during resetting and entrainment of OAVRT with right ventricular stimulation if the accessory pathway is septally located, since its insertion is relatively close to the stimulation site. This phenomenon can help in the differential diagnosis with atrioventricular nodal reentry (AVNR). METHODS AND RESULTS: We performed programmed right ventricular stimulation during regular inducible supraventricular tachycardia with concentric atrial activation in 44 patients--20 with OAVRT and 24 with AVNR. Fusion in the ECG morphology of extrastimuli producing resetting was observed in 19 of 19 OAVRT but in 0 of 11 AVNR reset (P < .001). Transient entrainment was demonstrated in all 31 cases undergoing rapid ventricular pacing (14 OAVRT and 17 AVNR). Entrainment with fusion occurred in 13 of 14 OAVRT and in 0 of 17 AVNR (P < .001). Fusion was critically dependent on the coupling intervals or pacing rates, sometimes having a narrow window for its observation. CONCLUSIONS: The relative proximity (conduction time) among pacing site, site of entrance to a reentrant circuit, and site of exit from the circuit to the paced chamber are critical for the occurrence of fusion during resetting and/or entrainment. The presence or absence of fusion during these phenomena can help in the differential diagnosis of certain supraventricular tachycardias.

Adolescent↗
PubMed1993

Treatment of ventricular arrhythmias in patients with hypertrophic cardiomyopathy.

In patients with hypertrophic cardiomyopathy, asymptomatic episodes of non-sustained ventricular tachycardia are frequent and of prognostic significance for sudden cardiac death in adults, particularly in those whose consciousness is impaired. Low-dose amiodarone, found to be beneficial in mildly symptomatic non-sustained ventricular tachycardia, but detrimental in a subgroup with prominent non-arrhythmic symptoms, could be an alternative to an electrophysiological approach in patients with syncope but preserved functional capacity. In cardiac arrest survivors, an electrophysiological approach seems preferable to empiric amiodarone, together with implantation of a defibrillator, at least in those in whom inducible arrhythmias cannot be suppressed.

Amiodarone↗
PubMed1992

Frequency and implications of resetting and entrainment with right atrial stimulation in atrial flutter.

Thirty-three patients (24 with typical and 9 with atypical flutter-wave morphology) were studied to evaluate the incidence and implications of resetting and entrainment of atrial flutter with right atrial stimulation. Resetting with single extrastimulus was present in 23 cases (group A) and absent in 10 (group B). Most cases of reset flutter were typical (20 of 23). Fixed fusion indicative of entrainment was observed in all 29 cases with pacing trains. Groups A and B did not differ significantly in flutter cycle length (230 +/- 20 vs 223 +/- 19 ms), atrial functional refractory period (165 +/- 18 vs 167 +/- 22 ms) or longest paced cycle length producing entrainment (213 +/- 19 vs 210 +/- 19 ms). In contrast, the return cycle after the longest paced cycle length producing entrainment was significantly shorter in group A (228 +/- 27 vs 284 +/- 56 ms; p = 0.001). The return cycle in group A was virtually identical to the flutter cycle length, whereas in group B it was greater (p = 0.002 compared with group A). Resetting was more frequent in typical than atypical flutter (20 of 24 vs 3 of 9; p = 0.01). Both typical and atypical flutter can be transiently entrained by right atrial pacing. Lack of resetting and longer return cycle, suggesting a longer conduction time between the reentrant circuit and the stimulation site, were mostly observed in atypical flutter. The data suggest a different location for both types of flutter, and may have implications for ablation techniques. A more cautious approach, with more extensive mapping, appears appropriate for ablation attempts of atypical flutter.

Adult↗
PubMed1992

Rate-dependent failure of ventricular capture in patients treated with oral propafenone.

The effects of propafenone on ventricular excitability were studied in 18 patients after 9 +/- 6 days on oral propafenone (900 mg/day). Late diastolic double threshold right ventricular stimulation was performed at variable rates. In five patients (28%, group I) an intermittent, rate-dependent failure of ventricular capture was reproducibly observed during stimulation at rates above the sinus rhythm but not exceeding 150 beats min-1. In four patients loss of capture was preceded by gradual prolongation of the interval between the stimulus artifact and the local right ventricular bipolar electrogram. Such findings were not observed in the remaining 13 patients (group II) on propafenone nor in 28 studies in the same patients on different antiarrhythmic agents. Group I vs group II patients were older (72 +/- 4 vs 53 +/- 18 years, P = 0.002), had longer right ventricular effective refractory periods on the baseline (P = 0.004) and on propafenone (P = 0.0003), and had longer QRS duration on propafenone. The increase produced by propafenone in sinus rhythm QRS duration, paced QRS duration and ventricular effective refractory period was greater in group I than in group II: 42 +/- 36 vs 14 +/- 12 ms, P = 0.01, 94 +/- 43 vs 34 +/- 26 ms, P = 0.0002, 88 +/- 64 vs 22 +/- 37 ms, P = 0.025, respectively. Thus propafenone can produce rate-dependent failure of ventricular capture which is associated with marked prolongation of refractoriness and QRS duration suggesting a marked use-dependent drug effect in selected patients.

Administration, Oral↗
PubMed1992

[The catheter ablation of accessory atrioventricular pathways using a radiofrequency].

Sixteen consecutive patients (5 males and 11 females) aged 40 +/- 22 years suffering for spontaneous symptomatic arrhythmias underwent attempted transcatheter ablation of an atrioventricular accessory pathway using radiofrequency current. Five patients had the WPW syndrome. The Kent bundle was located in the left free wall in 14 patients, in the right anteroseptal region in one patient and in the posteroseptal zone in one patient. A 7F catheter (Polaris, Mansfield) with a 4 mm2 distal electrode, was used for ablation positioned on the left atrioventricular annulus in the 13 patients with left free wall accessory pathways or at the right atrium in the two patients with right accessory pathways. Without general anesthesia, a mean of 12 +/- 9 applications of radiofrequency current were delivered between the large tip electrode and a large skin patch positioned on the left posterior chest. By using radiofrequency current, a successful clinical outcome was achieved in 14 of 16 patients (87%). In patients with concealed accessory pathways, accessory conduction was abolished in 10 of 11 patients, in 8 patients in the first radiofrequency session and in two other patients in a successful second procedure. In the 5 patients with the WPW syndrome, the anterograde conduction disappeared after the procedure but the retrograde conduction remained, although deteriorated, in 2 patients. One patient developed uncomplicated tibioperoneal thrombophlebitis and in 2 cases an elevated concentration of creatine kinase value was found. In one female patient with a concealed accessory pathway, the Kent bundle conduction reappeared 3 months after the procedure and was ablated in a second session.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗