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Andrew R J Mitchell

Publications and source records attributed to Andrew R J Mitchell.

30 records · Page 2Linked to original sources
PubMed2004

Echocardiographic assessment and percutaneous closure of multiple atrial septal defects.

Atrial septal defect closure is now routinely performed using a percutaneous approach under echocardiographic guidance. Centrally located, secundum defects are ideal for device closure but there is considerable morphological variation in size and location of the defects. A small proportion of atrial septal defects may have multiple fenestrations and these are often considered unsuitable for device closure. We report three cases of multiple atrial septal defects successfully closed with two Amplatzer septal occluders.

Adult↗
PubMed2004

How do atrial pacing algorithms prevent atrial arrhythmias?

With an ageing population, atrial fibrillation has become an increasing cause of hospital admission and morbidity. Pacemaker implantation may prevent atrial tachyarrhythmias by preventing bradycardia and pauses. Implantable devices are now available with specific atrial pacing algorithms designed to prevent atrial arrhythmias. These algorithms work by increasing the atrial pacing rate to achieve continuous overdrive pacing or by responding to triggers such as premature atrial complexes. This article examines how the algorithms work by describing the functions of one of the new generation of pacemakers in detail. Early studies have indicated that the use of preventative pacing can reduce atrial arrhythmia burden and symptomatic atrial fibrillation in selected patients. There are clearly some patients who benefit from implantation of these devices but what remains unclear is how to identify this patient group.

Algorithms↗
PubMed2004

Improving the acceptability of the atrial defibrillator for the treatment of persistent atrial fibrillation: the atrial defibrillator sedation assessment study (ADSAS).

BACKGROUND: To compare the acceptability and effectiveness of three pre-medication regimens for manually activated cardioversion of recurrent persistent atrial fibrillation. METHODS: Eighteen patients implanted with the Jewel AF atrial defibrillator for drug-resistant persistent atrial fibrillation only were studied in an open-labelled randomised crossover study. Patients were assigned to sedation (S) with midazolam elixir, analgesia (A) with morphine sulphate or combination therapy (C) with dextromoramide and lorazepam. Pre-medication was taken up to 1 h before cardioversion. Patients rotated through each type of medication after undertaking at least one cardioversion. Visual analogue scales were completed immediately post-cardioversion and 24 h later for pain, anxiety and 'unpleasantness'. Higher scores represented a worse outcome. RESULTS: After 2 years' follow-up, 238 cardioversions were performed with S, 17 with A and 35 with C. The mean immediate combined score for S (10.9, 95% confidence interval (CI) 8.2-13.6) was significantly lower than for A (17.3, 95% CI 15.1-19.5, P = 0.01) and for C (15.9, 95% CI 12.3-19.6, P = 0.02). All patients who used S chose it as the most favourable pre-medicant. All patients who used A found it the least acceptable. CONCLUSION: Sedation rather than analgesia enhanced the acceptability of manually activated atrial defibrillation.

Adult↗
PubMed2003

Echocardiographic changes and predictors of arrhythmia recurrence after long-term use of the atrial defibrillator.

BACKGROUND: The patient-activated atrial defibrillator allows patients to cardiovert themselves from atrial fibrillation soon after the onset of symptoms. The long-term effects of early cardioversion from persistent atrial fibrillation on left ventricular performance and left atrial size are unknown. METHODS: Eighteen patients, mean age 63.4, 83% male, had the Jewel((R)) AF atrial defibrillator implanted for persistent atrial fibrillation only. Transthoracic echocardiography was performed 3-monthly following implant. Parasternal long axis measurements were taken using conventional M-mode techniques. RESULTS: Over follow-up of 28.0+/-9 months, 377 episodes of persistent atrial fibrillation were terminated by patient-activated cardioversion (median 15 per patient). Echocardiographic measurements at implant were; left atrium 44+/-6 mm, left ventricular end-diastolic diameter 49+/-7 mm, left ventricular end-systolic diameter 34+/-7 mm, fractional shortening 33+/-10% and ejection fraction 65+/-17%. After 1 year there had been a significant decrease in mean left atrial size to 41+/-6 mm (P=0.02) and an increase in mean ejection fraction to 73+/-8% (P=0.04). At long-term follow-up however, all parameters reverted to pre-implant levels. Baseline echocardiographic variables did not predict which patients would demonstrate serial increases in sinus rhythm duration between shocks during long-term follow-up. Patients on antiarrhythmic drug therapy however were more likely to demonstrate "sinus rhythm begetting sinus rhythm". CONCLUSIONS: Use of the atrial defibrillator for spontaneous persistent atrial fibrillation is associated with a medium-term (1 year) reduction in left atrial size and an increase in ejection fraction. These changes were not maintained in the long-term. Synergistic therapy with antiarrhythmic drugs may prolong periods of sinus rhythm between arrhythmia recurrences.

Adult↗
PubMed2003

Does rapid atrial pacing terminate atrial fibrillation? A comparison of laboratory and device termination studies.

Atrial fibrillation is understood to be a re-entrant arrhythmia and for many years electrophysiologists have attempted to pace-terminate the rhythm. Several studies have demonstrated that an excitable gap is present during atrial fibrillation and that the capture of small amounts of atrial tissue is possible. Early attempts to terminate atrial fibrillation however were unsuccessful. The rapid development of pacemaker and defibrillator technology has provided an exciting new direction for the treatment of recurrent symptomatic atrial fibrillation. Results from studies of the effectiveness of atrial anti-tachycardia pacing algorithms have suggested that 50% of atrial arrhythmias (including atrial fibrillation) can be pace-terminated. These findings conflict with data from the electrophysiology laboratory where atrial fibrillation has yet to be convincingly terminated. In this review, the current literature is discussed and possible reasons for this discrepancy are proposed.

Algorithms↗
PubMed2003

Psychosocial aspects of patient-activated atrial defibrillation.

UNLABELLED: Atrial Defibrillator. INTRODUCTION: The atrial defibrillator empowers patients to cardiovert themselves from atrial arrhythmias at a time that is socially and physically acceptable, thereby preventing hospitalization. The long-term psychosocial effects of repeated use of the patient-activated atrial defibrillator at home are unknown. METHODS AND RESULTS: Eighteen patients underwent placement of the Jewel AF atrial defibrillator for persistent atrial fibrillation only. All patients performed manually activated cardioversions at home under self-administered sedation. Automatic shock therapies were disabled. Hospital Anxiety and Depression Scale and Multidimensional Health Locus of Control questionnaires were obtained before implant. All patients completed questionnaires 1 year after device implant and at long-term follow-up. The spouse or partner of each patient was interviewed to identify positive and negative aspects of manual cardioversion at home. The baseline patient scores for both anxiety (5.7 +/- 2.7) and depression (3.4 +/- 2.3) fell within the predefined range of normality. At 1 year, there was no significant change in anxiety (4.9 +/- 3.7, P = 0.39) or depression (2.4 +/- 1.8, P = 0.06). At long-term follow-up (mean 28 months), a total of 377 patient-activated cardioversions were performed out of hospital (median 15 per patient). Scores for anxiety (6.0 +/- 4.0, P = 0.70) and depression (3.2 +/- 2.5, P = 0.68) remained unchanged. CONCLUSION: During long-term follow-up, patient-activated cardioversion using the atrial defibrillator was not associated with increased anxiety or depression. The procedure was well tolerated by patients and their partners, offering an acceptable treatment option for patients with recurrent persistent atrial fibrillation.

Adult↗
PubMed2002

Atrial fibrillation in the new millennium--the role of pacemaker and defibrillator therapy.

Atrial fibrillation is the most common clinical arrhythmia and with an aging population it is becoming an increasing cause of morbidity and hospitalisation. Antiarrhythmic drug therapy unfortunately remains only moderately effective at preventing recurrences of arrhythmia. Attention has now therefore focussed on the development of non-drug techniques to prevent or treat atrial fibrillation in highly symptomatic patients. There are a number of theoretical ways that pacing the atrium may prevent arrhythmias and pacemakers are under investigation for the prevention and termination of atrial arrhythmias with additional tailored, programmable algorithms. The increased memory capacity and diagnostic capabilities of these devices allows the true efficacy of pacemaker interventions to be determined. Early results from studies suggest that the implantation of such pacemakers can reduce atrial fibrillation burden and thereby obviate the need for more invasive procedures such as atrioventricular nodal ablation. The improved diagnostics also provides enhanced information about the onset of atrial arrhythmias and suggests that atrial fibrillation may have periods of high organisation and a window for pace termination. The atrial defibrillator is a useful, but expensive, therapeutic option in patients with recurrent symptomatic persistent atrial fibrillation and the current generation of devices allow patients to activate the device at home using a hand-held activator. This reduces the need for hospitalisation and empowers the patient to 'take charge' of their condition.

Algorithms↗