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.

Radiofrequency catheter ablation of ventricular tachycardia from right ventricle late after myocardial infarction.

In summary, this case illustrates how complex VT circuits may be. If the findings of this case are substantiated with additional cases, mapping and radiofrequency energy application from right ventricle would have to be considered in VT with left bundle branch blocks QRS morphology, whenever ablation from the left ventricule is ineffective.

[The current status of implantable automatic defibrillators]. / Estado actual de los desfibriladores automáticos implantables.

The implantable cardioverter defibrillator has become an important therapy for patients with sustained or life threatening ventricular arrhythmias. Although the concept for the implantable cardioverter defibrillator originated in the late 1960s, the first device was implanted in humans in 1980. Since then, the technology has improved rapidly the design, function and reliability of the devices have been greatly modified. There are currently five companies dealing with defibrillators in Spain incorporating multiple options in defibrillation, pacing and sensing capabilities. New devices with atrioventricular pacing and atrial defibrillation possibilities will soon become available. The purpose of this article is to review the principal functions of implantable cardioverter defibrillators currently available.

[Massive myocardial infiltration by lymphoma of tonsilar origin simulating left ventricular hypertrophy: diagnosis using echocardiography]. / Infiltración miocárdica masiva por linfoma de origen amigdalar que simula hipertrofia ventricular izquierda: diagnóstico mediante ecocardiografía.

We present the first described case in the literature of isolated left anterior hemiblock, in the setting of massive myocardial invasion by a primary tonsilar lymphoma. Such process evolved with a morphologic pattern mimicking left ventricular hypertrophy of unequal distribution. An hemodynamic behaviour of an infiltrative cardiomyopathy, with both systolic and diastolic important ventricular dysfunction, was observed. An early presumptive diagnosis of severe lymphomatous myocardial invasion was established by echocardiography. The pathologic examination confirmed it subsequently.

[Sudden cardiac death out of the hospital and early defibrillation]. / Muerte súbita cardíaca extrahospitalaria y desfibrilación precoz.

Since most sudden cardiac death victims show neither symptoms before the event nor other signs or risk factors that would have identified them as a high risk population before their cardiac arrest, emergency out-of-hospital medical services must be improved in order to obtain a higher survival in these patients. Early defibrillation is an essential part of the chain of survival that also includes the early identification of the victim, activation of the emergency medical system, immediate arrival of trained personnel who can perform basic cardiopulmonary resuscitation and early initiation of advanced cardiac life support that would raise the survival rate for sudden cardiac arrest victims. Many studies have demonstrated the enormous importance of early defibrillation in patients with a cardiac arrest due to ventricular fibrillation. The most important predictor of survival in these individuals is the time that elapses until electric defibrillation, the longer the time to defbrillation the lower the number of patients who are eventually discharged. Multiple studies have demonstrated that automatic external defibrillation will reduce the time elapsed to defibrillation and thus improve survival. For these reason, public access defibrillation to allow the use of automatic external defibrillators by minimally trained members of the lay public, has received increasing interest on the part of a groving number of companies, cities or countries. The automatic external defibrillaton, as performed by a lay person is being investigated. The liberalization of its application, if is demonstrated to be effective, will need to be accompanied by legal measures to endorse it and appropriate health education, probably during secondary education.

[The catheter ablation of accessory atrioventricular pathways using a radiofrequency]. / Ablación mediante catéter de vías accesorias auriculoventriculares utilizando radiofrecuencia.

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)

[Radiofrequency treatment of tachyarrhythmias in children and adolescents]. / Tratamiento con radiofrecuencia de taquiarritmias en 28 niños y adolescentes.

INTRODUCTION: Radiofrequency ablation has been extensively used in adults to treat supraventricular and ventricular tachycardia. In children and adolescents few data are available on its safety and efficacy. METHODS: 28 patients (mean age 12.8) with symptomatic tachyarrhythmias underwent catheter ablation; 21 children had atrioventricular accessory pathways (11 right connections, 9 lef connections and one midseptal pathway), 3 had intranodal tachycardia, 2 had ventricular tachycardia and 2 had atrial tachycardia. Only four patients had associated structural anomalies. RESULTS: Success rate was 71.4% (20 patients). The success per cents in each group were: in intranodal tachycardias 100%; we failed in the two patients with ventricular tachycardias; in accessory pathways 76.1% and 50% in atrial tachycardia. There were no recurrences of arrhythmia in a mean chase period of 24 months (12-46). Major complications were only observed in one patient who developed a Wallenberg syndrome after ablation. CONCLUSIONS: Radiofrequency catheter ablation appears to be a safe and effective method to treat arrhythmias in children and adolescents, which in most cases can supersede surgery. Alow incidence of complications is reported, although long term damage on endocardial structures remains yet to be determined.

A novel device based on smart textile to control heart's activity during exercise.

In recent years, several systems have been developed to control cardiac function during exercise, and some are also capable of recording RR data to provide heart rate variability (HRV) analyses. In this study we compare time between heart beats and HRV parameters obtained with a smart textile system (GOW; Weartech sl., Spain) and an electrocardiogram machine commonly used in hospitals during continuous cycling tests. Twelve cardiology patients performed a 30-min cycling test at stable submaximal intensity. RR interval data were recorded during the test by both systems. 3-min RR segments were taken to compare the time intervals between beats and HRV variables using Bland-Altman analyses and intraclass correlation coefficients. Limits of agreement (LoAs) on RR intervals were stable at around 3 ms (widest LoAs -5.754 to 6.094 ms, tightest LoAs -2.557 to 3.105 ms, medium LoAs -3.638 ± 0.812 to 3.145 ± 0.539 ms). HRV parameters related to short-term change presented wide LoAs (RMSSD -0.17 to 18.41 %, HF -17.64 to 33.21 %, SD1 -0.50 to 17.54 %) as an effect of the error measurement of the GOW system. The GOW system is a valid tool for controlling HR during physical activity, although its use as a clinical tool for HRV cannot be supported.

Echocardiographically revealed collapse of the right ventricle and prolonged inversion of both atria without clinical cardiac tamponade.

In a patient with a large pericardial effusion without any clinical signs of cardiac tamponade, echocardiography revealed collapse of the right ventricle and prolonged (greater than 34%) inversion of the free wall of both atria, maximal in early systole. The presence of such findings in the absence of clinical signs of haemodynamic compromise is discussed.

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.

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.