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Biomedical subjects

A Arenal

Publications and source records attributed to A Arenal.

At least 19 recordsLinked to original sources
PubMed2000

Growth efficiency in transgenic tilapia (Oreochromis sp.) carrying a single copy of an homologous cDNA growth hormone.

Growth hormone (GH) has been shown to have a profound impact on fish physiology and metabolism. However, detailed studies in transgenic fish have not been conducted. We have characterized the food conversion efficiency, protein profile, and biochemical correlates of growth rate in transgenic tilapia expressing the tilapia GH cDNA under the control of human cytomegalovirus regulatory sequences. Transgenic tilapia exhibited about 3.6-fold less food consumption than nontransgenic controls (P < 0.001). The food conversion efficiency was significantly (P < 0.05) higher (290%) in transgenic tilapia (2.3 +/- 0.4) than in the control group (0.8 +/- 0.2). Efficiency of growth, synthesis retention, anabolic stimulation, and average protein synthesis were higher in transgenic than in nontransgenic tilapia. Distinctive metabolic differences were found in transgenic juvenile tilapia. We had found differences in hepatic glucose, and in agreement with previous results we observed differences in the level of enzymatic activities in target organs. We conclude that GH-transgenic juvenile tilapia show altered physiological and metabolic conditions and are biologically more efficient.

Animals↗
PubMed2000

[Predictors of sudden death in coronary artery disease].

Although advances in the management of acute myocardial infarction have resulted in a decline in long-term risk of sudden death, it continues to be high in certain subsets of patients. Thus, it is important to identify and treat these patients. Left ventricular ejection fraction less than 0.40, frequent premature ventricular ectopy on Holter monitoring, late potentials on signal-averaged electrocardiogram, impaired heart rate variability, abnormal baroreflex sensitivity and inducible sustained monomorphic ventricular tachycardia during electrophysiological study are predictors of sudden death and arrhythmic events. Although the negative predictive value of each factor is high, the positive predictive accuracy is low. Several tests can be combined to obtain higher positive predictive values. In fact, in some studies combined noninvasive tests have been used to select patients for ventricular stimulation study. Some preventive treatment can be applied in these patients. Available data do not justify prophylactic therapy with amiodarone in high-risk survivors of acute myocardial infarction. Sudden death and total mortality have been significantly reduced in postinfarction patients by long-term beta blockade. Hence, beta blockers should be given to all patients with acute myocardial infarction who do not have contraindications to their use. The MADIT study has shown the beneficial effect of implantable cardioverter defibrillator in reducing mortality in patients with prior myocardial infarction, an ejection fraction less than 0.36, asymptomatic nonsustained ventricular tachycardia, and inducible sustained ventricular tachycardia, unsuppressable by procainamide. Besides, several studies are under way to evaluate the prophylactic use of implantable defibrillator for improving survival in high-risk patients.

Coronary Disease↗
PubMed1999

Rate-dependent conduction block of the crista terminalis in patients with typical atrial flutter: influence on evaluation of cavotricuspid isthmus conduction block.

BACKGROUND: The crista terminalis (CT) has been identified as the posterior boundary of typical atrial flutter (AFL) in the lateral wall (LW) of the right atrium (RA). To study conduction properties across the CT, rapid pacing was performed at both sides of the CT after bidirectional conduction block was achieved in the cavotricuspid isthmus by radiofrequency catheter ablation. METHODS AND RESULTS: In 22 patients (aged 61+/-7 years) with AFL (cycle length, 234+/-23 ms), CT was identified during AFL by double electrograms recorded between the LW and posterior wall (PW). After the ablation procedure, decremental pacing trains were delivered from 600 ms to 2-to-1 local capture at the LW and PW or coronary sinus ostium (CSO). At least 5 bipolar electrograms were recorded along the CT from the high to the low atrium next to the inferior vena cava. No double electrograms were recorded during sinus rhythm in that area. Complete transversal conduction block all along the CT (detected by the appearance of double electrograms at all recording sites and craniocaudal activation sequence on the side opposite to the pacing site) was observed in all patients during pacing from the PW or CSO (cycle length, 334+/-136 ms), but it was fixed in only 4 patients. During pacing from the LW, complete block appeared at a shorter pacing cycle length (281+/-125 ms; P<0.01) and was fixed in 2 patients. In 3 patients, complete block was not achieved. CONCLUSIONS: These data suggest the presence of rate-dependent transversal conduction block at the crista terminalis in patients with typical AFL. Block is usually observed at longer pacing cycle lengths with PW pacing than with LW pacing. This difference may be a critical determinant of the counterclockwise rotation of typical AFL.

Aged↗
PubMed1999

[Internal cardioversion with low-energy shocks in atrial fibrillation resistant to external electric cardioversion].

BACKGROUND AND OBJECTIVE: Although external electrical cardioversion is effective in most patients with atrial fibrillation, there are cases refractory to external cardioversion. This study is aimed at showing our initial experience with an internal cardioversion system in patients with previous unsuccessful external cardioversion. PATIENTS AND METHODS: Between February, 1997 and September, 1998 nine consecutive patients with spontaneous chronic or persistent atrial fibrillation that failed external cardioversion, were included. Internal cardioversion was performed under sedation with two electrodes that had a 5.5 cm coil placed in the lateral right atrium and coronary sinus. Both electrodes were connected to an external defibrillator capable of delivering R-wave synchronized low-energy biphasic shocks following a minimum RR interval of 500 ms. Energy between 2 J and 10 J was applied until the restoration of sinus rhythm or a maximum of 2 shocks of 10 J. RESULTS: Sinus rhythm was achieved in the nine patients, but in two of them atrial fibrillation recurred after a few beats. Both had underlying structural heart disease. The other 7 patients, 5 of them without structural heart disease, were in sinus rhythm at discharge. No mechanic complications or ventricular arrhythmias were observed. Six patients are in sinus rhythm after 4 +/- 3 months of follow-up. CONCLUSIONS: Low-energy intracardiac cardioversion is useful in some patients with atrial fibrillation that had failed external cardioversion and can be performed without general anesthesia.

Adult↗
PubMed1999

[Radiofrequency ablation of ventricular tachycardia in patients with ischemic cardiopathy].

PURPOSE: We analyze the efficacy of radiofrequency catheter ablation and the clinical significance of inducible ventricular tachycardia that had never been documented before (non clinical ventricular tachycardia) in patients with ventricular tachycardia and coronary artery disease. METHODS: Thirty-four patients (30 men, aged 61 +/- 10 years, left ventricular ejection fraction 31 +/- 10%) with coronary artery disease and documented clinical ventricular tachycardia underwent radiofrequency ablation. Thirty-four clinical ventricular tachycardia and 11 non clinical ventricular tachycardia were treated with radiofrequency. Initial therapeutic success was considered when none of the ventricular tachycardia treated with radiofrequency could no longer be induced at the last stimulation protocol before discharge. RESULTS: Clinical ventricular tachycardia was successfully ablated in 23 patients (68%). Initial therapeutic success was obtained in 21 patients (62%). In 6 of them, 7 non clinical ventricular tachycardia poor tolerated were also induced. During a mean follow-up of 26 +/- 15 months ventricular tachycardia recurred in 6 patients (29%). Five of the 6 patients who recurred were discharged with no inducible non clinical ventricular tachycardia. Three patients died during the follow-up. Two of them from heart failure (one with previous recurrence) and the other suddenly with documented asystole after loss of consciousness without previous recurrence. CONCLUSIONS: In our series of patients with ventricular tachycardia and coronary artery disease selected for radiofrequency ablation, acute success was obtained in 62%. After a mean follow-up of 2 years, 44% of all the patients were free from ventricular tachycardia. Although the possibility of ventricular tachycardia recurrence is high (29%), the recurrence rate is not increased by the inducibility of non clinical ventricular tachycardia.

Aged↗
PubMed1998

First postpacing interval variability during right ventricular stimulation: a single algorithm for the differential diagnosis of regular tachycardias.

BACKGROUND: Failure to differentiate supraventricular from ventricular arrhythmias is the most frequent cause of inappropriate implantable cardioverter-defibrillator therapies. Although a sudden-onset criterion is available to differentiate sustained monomorphic ventricular tachycardias (SMVTs) and sinus tachycardias (STs), SMVTs arising during ST and SMVTs gradually accelerating above the cutoff rate can remain undetected. Regular paroxysmal atrial tachycardias (ATs) also can be undetected by onset and stability algorithms. We hypothesized that the first postpacing interval (FPPI) variability after overdrive right ventricular pacing may differentiate SMVTs from STs and ATs. METHODS AND RESULTS: FPPI variability was measured in 23 SMVTs (cycle length [CL] 366+/-50 ms [VT group]), 27 supraventricular tachycardias, 15 episodes of induced or simulated ATs (CL 376+/-29 ms [AT group]), and 12 exercise-related STs (CL 381+/-24 [ST group]). Sequences of trains of 5, 10, and 15 beats were delivered with a CL 40 ms shorter than the tachycardia CL. An FPPI absolute mean difference between consecutive trains of 5 and 10 beats (deltaFPPI) < or =25 ms identified all VTs (mean difference 5+/-7 ms). In the AT group, the deltaFPPI was >25 ms in all sequences (mean difference 129+/-60 ms, P<0.01). In the ST group, the deltaFPPI was >50 ms in all STs (mean difference 118+/-47 ms, P<0.01). CONCLUSIONS: FPPI variability may differentiate SMVT from AT and ST. This criterion is potentially useful in implantable devices that use a single ventricular lead.

Algorithms↗
PubMed1997

Analysis of the degree of QRS fusion necessary for its visual detection: importance for the recognition of transient entrainment.

BACKGROUND: Fixed fusion is the hallmark for the demonstration of transient entrainment. However, the degree of accuracy of its recognition on the surface ECG is unknown. The purpose of the present study was to evaluate the ability to detect fusion in the QRS complex. METHODS AND RESULTS: While pacing the ventricles at a fixed rate, a model of ventricular fusion was created by introducing late extra stimuli at a second site. In this model, the presence and degree of fusion are known. Pacing sites were the RV apex, outflow tract, and left ventricle in various configurations. We analyzed 433 QRS complexes with different degrees of fusion (or no fusion) in 21 patients. Each QRS was "read" by three investigators blinded to intracardiac recordings but having a reference QRS with no fusion. There was a statistically significant correlation between the degree of fusion and its recognition. Fusion was detected with a sensitivity of 75% and a specificity of 87%. Fusion was accurately detected in all configurations only when >22% of the QRS was fused. In patients with organic left ventricular disease, fusion was better recognized when the driving pacing site was the left ventricle than when it was a right ventricular site. The interobserver agreement was moderate between two pairs of observers and only fair between the remaining pair. CONCLUSIONS: Our results suggest that an accurate detection of ventricular fusion can only be accomplished when fusion occurs during a significant proportion of the QRS duration. The potential lack of recognition of minor degrees of fusion may produce underdetection of transient entrainment.

Adult↗
PubMed1997

Mechanism and location of atrial flutter in transplanted hearts: observations during transient entrainment from distant sites.

OBJECTIVES: This study was designed to elucidate the location and mechanism of typical atrial flutter in the transplanted heart. BACKGROUND: Although the F wave morphology in atrial flutter is similar in nontransplanted and transplanted hearts, the surgical incision needed for the atrial anastomosis may create a distinct electrophysiologic substrate of atrial flutter. METHODS: Entrainment from the lateral wall of the right atrium and interatrial septum was used to determine the location of atrial flutter in five patients with a transplanted heart and six patients with a nontransplanted heart. The difference between the first postpacing interval (FPPI) and the flutter cycle length (FCL) was used as an index of proximity to the circuit. RESULTS: In the transplant group, the FPPI was equal to the FCL at sites located close to the tricuspid annulus (TA); the mean differences (+/-SD) were 1 +/- 5 and -1 +/- 2 ms at the lateral wall and interatrial septum, respectively. However, from sites close to the surgical incision at the lateral wall and at the interatrial septum, these differences were significantly longer (29 +/- 12 and 27 +/- 9 ms, respectively, p < 0.05). In the nontransplant group, the FPPI was similar to the FCL at points in the lateral wall and interatrial septum close to the TA (mean difference 7 +/- 6 and 6 +/- 11 ms, respectively) and at sites close to the crista terminalis (CT) in the lateral wall (mean difference 4 +/- 4 ms). However, in sites separated from the TA at the interatrial septum the difference was markedly longer (35 +/- 11 ms, p < 0.05). CONCLUSIONS: Atrial flutter in transplanted hearts may best be explained by macroreentry around the tricuspid ring. In non-transplanted hearts a different structure (perhaps the CT?) may be the basis for atrial flutter at the lateral wall.

Atrial Flutter↗
PubMed1996

"Pseudodisappearance" of atrial electrogram during orthodromic tachycardia: new criteria for successful ablation of concealed left-sided accessory pathways.

OBJECTIVES: This study sought to analyze two new criteria along with other known predictors of success of radiofrequency ablation. Background. Although the overall success rate of radiofrequency ablation of accessory pathways is high, the individual predictive value of each of the established criteria is low. METHODS: We prospectively studied the local electrograms obtained before the application of radiofrequency energy in 33 patients with a left-sided concealed accessory pathway successfully ablated. Two new criteria ("pseudodisappearance" during tachycardia of a bipolar atrial electrogram visible during sinus rhythm and the presence of an "atrial notch" in the ascending limb of the unipolar ventricular electrogram during tachycardia) were studied along with other known predictors. Electrograms recorded at a total of 157 sites were analyzed (33 successful applications, 124 failures). RESULTS: Electrogram characteristics that were predictive of success during ablation on the basis of univariate analyses were a pseudodisappearance criterion (p<0.001), the presence of a Kent potential (p<0.005) and the presence of an "atrial notch" (p<0.005). After adjustment for between-patient differences, logistic regression analysis showed that only the "pseudodisappearance" criterion (odds ratio [OR] 7.2, 95% confidence interval [CI] 1.2 to 42.5, p<0.03) and the presence of a Kent potential (OR 2.4, 95% CI 1.01 to 5.79, p<0.05) had independent predictive value. CONCLUSIONS: The pseudodisappearance during tachycardia or ventricular pacing of a bipolar atrial electrogram present during sinus rhythm is associated with a good outcome during radiofrequency ablation of concealed accessory pathways. These observations may help to ablate accessory pathways and to avoid missing appropriate sites for ablation when the atrial activation is not clearly visible at the local electrogram.

Adolescent↗
PubMed1996

Incidence and clinical significance of multiple consecutive, appropriate, high-energy discharges in patients with implanted cardioverter-defibrillators.

BACKGROUND: Some patients with an automatic implantable cardioverter-defibrillator (ICD) suffer multiple appropriate, consecutive, high-energy discharges (MCDs) during follow-up. Such events might represent resistant ventricular arrhythmias and might have prognostic significance. METHODS AND RESULTS: Eighty consecutive patients with an ICD were followed up for up to 82 months (mean, 21 +/- 19 months). Thirty-eight patients had survived an out-of-hospital cardiac arrest and 42 had recurrent ventricular tachycardia. During follow-up, 16 patients had MCD (group A), 26 patients had episodes of single appropriate discharges (group B), and 38 patients had no appropriate discharges (group C). Group A patients had worse functional status (P = .001), lower left ventricular ejection fractions (LVEFs) (P = .001), and lower survival rates (log rank, P = .003) than the remaining two groups of patients. Cox analysis showed LVEF (P = .001) to be an independent predictor of MCD. Independent predictors of death or heart transplant were MCD (P = .001), female sex (P = .001), age (P = .001), history of cardiac arrest (P = .003), and functional status (P = .003). The only independent predictor of total mortality was female sex (P = .002). Independent predictors of cardiac death were MCD (P = .007) and female sex (P = .018). Independent predictors of arrhythmic death were age (P = .001), female sex (P = .02), and MCD (P = .023). CONCLUSIONS: In patients with an ICD, the development of MCD is an independent predictor of cardiac and arrhythmic mortality. If this finding is confirmed in larger studies, it may help to identify patients in whom other therapeutic alternatives, ie, heart transplantation, should be considered during follow-up after ICD implantation.

Aged↗
PubMed1996

[Electric treatment of atrial fibrillation].

In the present manuscript the information concerning electrical therapy of atrial fibrillation (AF) to prevent its development and to control its consequences (excluding ablation which will be covered in separate manuscripts of this series) is reviewed. Both presently conventional approaches and those undergoing investigation will be considered, under three general headings. Electrical stimulation to prevent the development of AF. Based on non controlled studies comparing VVI stimulation with other modalities that include stimulation of the atria, it was suggested that atrial stimulation could prevent AF recurrences in patients with sinus node dysfunction. This concept has been questioned in recent studies. In contrast, the hypothesis that specific ways of atrial stimulation (stimulation at sites other than the high right atrium, multisite simultaneous or with certain "delays" atrial stimulation) may be more efficacious is presently under enthusiastic assessment. Electrical stimulation to control ventricular response. Despite the evidence that ventricular stimulation may contribute to regularization and rate control during AF, its quantitative value seems to be scarce and, thus, is not of regular use in practice. Automatic implantable atrial defibrillator. Both animal experiments and clinical studies have demonstrated that the atria can be defibrillated using intracavitary electrodes with less than 3 joules in most cases, and without risk of inducing ventricular tachyarrhythmias as long as shocks are synchronized to the R wave and the preceding R-R interval is not short. Although an implantable atrial defibrillator is already undergoing clinical evaluation, the subject of tolerability of patients to shocks for non malignant arrhythmias is still controversial, since even low energy shocks seem to be painful.

Atrial Fibrillation↗
PubMed1996

[Comparative study of 3 algorithms to localize the accessory pathway in Wolff-Parkinson-White syndrome].

BACKGROUND AND OBJECTIVES: Some electrocardiographic algorithms have been developed to predict the location of the accessory pathway in the WPW syndrome. Few studies address the interobserver variability of such algorithms and the possible observer-dependent changes of accuracy. This study analyzes three algorithms to localize accessory pathways recently published, comparing the inter-observer variability, their predictive value and the most frequent problems observed during their application. METHODS: Ninety-six electrocardiograms from patients who underwent successful ablation of a single accessory pathway were reviewed. The location of each pathway was predicted by two independent observers according to three different reported electrocardiographic algorithms. The interobserver agreement, percentage of correct predictions and critical steps of each algorithm were analyzed. RESULTS: The interobserver agreement varied between 64 and 79% and the accuracy between 38 and 67%. The best results were obtained in the left lateral accessory pathways (69 to 89% correctly located). All the algorithms presented critical steps at which more than 20% of pathways were incorrectly classified. CONCLUSIONS: The analyzed algorithms present a high interobserver variability. The accuracy obtained is clearly lower than that reported by the corresponding authors. These facts should be considered when being used them in clinical settings.

Adult↗
PubMed1996

[Bradycardia and asystolia secondary to epileptic crisis. Report of a case].

We report the case of a 21 year old man with bradycardia and asystolia after a seizure. No cardiac disease could be demonstrated, but electroencephalography after sleep deprivation showed the presence of a temporal irritative focus. The importance of differential diagnosis between cardiogenic syncope and loss of consciousness due to epilepsy is discussed.

Adult↗
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↗