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J Alzueta

Publications and source records attributed to J Alzueta.

4 recordsLinked to original sources
PubMed2003

Diagnostic value of onset-recordings and marker annotations in dual chamber pacemaker stored electrograms.

AIMS: Stored electrograms (EGM) have recently been introduced into pacemaker therapy. New generation devices offer the possibility to store the onset of the EGM (several seconds preceding storage trigger) and marker annotations. The aim of the study was to evaluate whether the diagnostic capabilities of EGMs are improved by these new features. METHODS: We studied 65 patients (age 68+/-12 years, 41 male) implanted with a DDDR-system (PulsarMax II 1280; Guidant). During a 1-month period 319 EGMs have been recorded. EGM triggers were: Ventricular Tachycardia (VT), Non-Sustained VT (NSVT), Atrial Tachycardia Response (ATR), Pacemaker Mediated Tachycardia (PMT) and Sudden Bradycardia Response (SBR). First, each EGM was analysed with onset and markers blinded. EGMs were classified with respect to their trigger as confirmed, not-confirmed or false-positive. Analysis was then repeated with markers visible but without onset, and thereafter vice versa. Finally, EGMs were analysed with both features. It was noted whether the presence of marker annotations and/or onset-recording changed the initial classification of the stored EGMs. RESULTS: 169 EGMs were triggered by SBR, which can only be confirmed with onset recording. False positive EGMs (atrial undersensing) occurred in 12%. The remaining 150 EGMs were triggered by ATR (80%), NSVT (11%), VT (6%) and by PMT (3%). Without onset/markers 37 of these 150 EGMs (25%) could not be confirmed. With markers and onset 33/37 (89%) of these EGMs could now be classified as confirmed or false positive. These EGMs became diagnostic with onset alone in 24%, with markers alone in 24%, and with the combination of both in 41%. In 4 EGMs no definite diagnosis could be established. CONCLUSION: Stored electrograms provide direct insights into device function, thereby providing a validation of diagnostic data. The expanded recording of onset and markers results in markedly improved diagnostic capabilities - compared with conventional EGMs. These new features were necessary to interpret correctly 61% of all stored electrograms, without which a diagnosis would not have been possible. Both onset-recording and marker annotation are necessary for optimal analysis.

Aged↗
PubMed2000

Profiling risk from arrhythmic or hemodynamic death.

Congestive heart failure is increasing in prevalence and, despite recent advances in therapy, mortality remains high. Sudden cardiac death (SCD) represents a significant percentage of overall mortality, accounting for almost 1 in 2 deaths in patients with congestive heart failure. In patients with asymptomatic left ventricular dysfunction or mild degrees of functional impairement, overall annual mortality is low, although a significant portion of the deaths are sudden; on the other hand, in advanced heart failure annual mortality increases, but SCD contributes to it to a lesser degree. The mechanisms of SCD in heart failure are multiple, including ventricular tachycardia/ventricular fibrillation, bradyarrhythmias, electromechanical dissociation, acute coronary events, and thromboembolic events. Only a minority of patients with advanced heart failure or on the waiting list for heart transplant experience SCD as a consequence of ventricular tachycardia (VT) or ventricular fibrillation (VF). The availability of effective therapies to prevent sudden arrhythmic death, such as that provided by automatic implantable cardioverter defibrillators, may help to reduce the burden of SCD in congestive heart failure, but major efforts will be needed to identify the candidates who may benefit from this approach.

Arrhythmias, Cardiac↗
PubMed1990

Electrophysiology of heterotopic heart transplant: experimental study in dogs.

Electrophysiological properties were studied in a heterotopic heart transplant model developed in 44 dogs (Group I). Cycle length was 359.5 +/- 55.2 ms in the recipient heart and 500.9 +/- 77.9 ms in the donor heart (P less than 0.001). Sinoatrial conduction time was 38.6 +/- 13.6 ms in the recipient heart and 38.6 +/- 10.4 ms in that of the donor (not significant). The Wenckebach point was 175.4 +/- 31.1 ms in the recipient organ and 214.3 +/- 42.6 ms in the donor heart (P less than 0.001). The retrograde block point was 271.6 +/- 48.0 ms in the recipient heart and 353.6 +/- 47.3 ms in that of the donor (P less than 0.01). The effective antegrade refractory period was 133.4 +/- 28.7 ms in the recipient heart and 167.3 +/- 46.3 ms in the donor organ (P less than 0.001). An epicardial atrial cartography was performed at 44 preset points in both hearts, revealing a normal activation sequence and delays of 36-98 ms (mean 58 ms) in the recipient heart and from 39 to 59 ms (mean 50 ms) in the donor heart (not significant). In another 11 dogs (Group II), the same electrophysiological study was carried out under basal conditions and after pharmacological blockade of the autonomic nervous system with atropine (0.04 mg (kg body weight)-1) and propranolol (0.2 mg (kg body weight)-1). No significant differences were found in any of the parameters studied upon comparison of Group II animals in basal conditions with Group I recipients, and Group II dogs after blockade with Group I donors. These results demonstrate that the differences in automatism, conduction and refractoriness between the donor and recipient hearts are not attributable to differences in the haemodynamic situation or in the anaesthetic technique, but to denervation.

Animals↗