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Biomedical subjects

Jeff Healey

Publications and source records attributed to Jeff Healey.

7 recordsLinked to original sources
PubMed2006

ASymptomatic atrial fibrillation and Stroke Evaluation in pacemaker patients and the atrial fibrillation Reduction atrial pacing Trial (ASSERT).

Asymptomatic atrial fibrillation (AF) is common and may have the same prognostic implications as symptomatic AF. Among patients receiving dual-chamber pacemakers, it is now possible to quantify asymptomatic AF accurately. Most of these episodes are of short duration, often lasting only seconds to minutes and are called atrial high-rate episodes (AHRE) to distinguish them from the longer episodes of overt AF. To understand properly the clinical importance of asymptomatic AF, a large study of pacemaker patients without clinically overt AF is required. ASSERT is a multicenter, cohort follow-up, and single-blinded randomized trial in elderly hypertensive patients with a pacemaker recently implanted for sinus or atrioventricular node disease. The goals of this trial are to evaluate whether the detection of AHRE with pacemaker telemetry predicts an increased risk of stroke and other vascular events and to evaluate if atrial overdrive pacing reduces symptomatic AF. ASSERT is evaluating the hypothesis that among pacemaker patients without a previous history of AF, detection of AHRE predicts an increased risk of stroke and systemic embolism. The second hypothesis to be tested is that overdrive atrial pacing will reduce the risk of symptomatic AF in pacemaker patients without a previous history of AF. Finally, a 400-patient substudy will use the noninvasive testing capabilities of the patients' pacemaker to evaluate changes in atrial electrophysiology over 2 years. This substudy will determine if atrial electrical remodeling is detectable in pacemaker patients and if it is associated with the development of AF.

Aged↗
PubMed2004

Human study of biatrial electrical coupling: determinants of endocardial septal activation and conduction over interatrial connections.

BACKGROUND: The relative contribution of the atrial septum and interatrial connections to biatrial activation is a fundamental concept of human cardiac electrophysiology that has yet to be fully characterized. The purpose of the present study was to determine how both atria are coupled electrically. METHODS AND RESULTS: Twenty patients (16 men; mean age 54+/-11years) with a history of symptomatic atrial fibrillation (AF) underwent simultaneous biatrial noncontact mapping before catheter ablation of AF. The multiple electrode array catheters were positioned, respectively, in the left atrium (LA; transseptally) and the right atrium (RA). In all but 2 patients, isopotential maps revealed that endocardial septal activations of the RA and LA were separate, independent, and asynchronous of each other. Interatrial conduction was related to the site of initial atrial depolarization, revealing conduction over Bachmann's bundle in all patients during sinus rhythm, high RA pacing, and pacing from the LA appendage. Pacing from the coronary sinus was associated with conduction over the interatrial connection at the level of the coronary sinus in all patients, and conduction over Bachmann's bundle also occurred in 5 (26%) of 19 patients. Interatrial conduction over the fossa ovalis occurred in only 2 (2%) of the 116 segments analyzed. CONCLUSIONS: Electrical coupling of the RA and LA in humans is predominantly provided by muscular connections at the level of Bachmann's bundle and the coronary sinus. The true septum (the fossa ovalis and its limbus) of the RA and LA is asynchronous and discordant, usually without contralateral conduction during sinus rhythm or atrial pacing.

Adult↗
PubMed2004

The management of patients with carotid sinus syndrome: is pacing the answer?

Carotid sinus syndrome (CSS) is an under recognized cause of recurrent unexplained syncope and potentially of recurrent falls in the elderly. The mechanisms that lead to syncope in patients with CSS remain debated. However, evidence for both peripheral and central alterations have been recently reported. The diagnosis of CSS is challenging and a high clinical suspicion is usually needed to make the diagnosis. Clinical presentation may be typical and characterized by a clear association between accidental manipulation of the carotid sinus and the presentation of syncope. On the other hand, recurrent unexplained syncope and unexplained falls may be the clinical presentation of patients with CSS without a specific trigger. Carotid sinus hypersensitivity documented by carotid sinus massage (CSM) may be the only finding indicating the possibility of CSS as the cause of syncope. In older patients with recurrent unexplained syncope and a negative diagnostic work-up, carotid sinus massage both in the supine and upright positions is recommended. CSS may present primarily as a cardioinhibitory response or a true vasodepressor response. Therapy should address any underlying pathology if present, and be directed to either prevent cardioinhibition, vasodepression or both alterations. A variety of medical therapies have been used with unclear effects. No appropriately designed controlled clinical trials have been performed comparing pacing with medical therapy. Nonetheless, available information indicates that pacing may have a strong beneficial effect and prevents recurrence of syncope in patients with CSS. The present paper critically reviews the latest insights in the pathophysiology, diagnosis and management of CSS.

Cardiac Pacing, Artificial↗
PubMed2003

Atrial fibrillation after cardiac surgery: update on the evidence on the available prophylactic interventions.

Post-operative atrial fibrillation is very common. It is associated with increased length of ICU and hospital stay, and costs of post-operative care of patients after cardiac surgery. More then seventy trials on the pharmacological and non-pharmacological interventions were conducted since 1970's. Meta-analysis of these trials, together with detailed analysis of the largest of these trials suggested that conventional beta-blockers, sotalol, amiodarone and bi-atrial overdrive pacing are effective in prevention of post-operative atrial fibrillation. Amiodarone and bi-atrial pacing may decrease the length of hospital stay.

Adrenergic beta-Antagonists↗
PubMed2003

Thiamine deficiency in congestive heart failure patients receiving long term furosemide therapy.

OBJECTIVE: To assess the presence of thiamine deficiency in congestive heart failure patients receiving furosemide therapy. DESIGN: Prospective, biochemical analysis of thiamine status was performed in outpatients and inpatients of the University of Ottawa Heart Institute. SUBJECTS: Thirty-two patients with congestive heart failure who received at least 40 mg/day of furosemide were included. Patients were then separated into two groups depending on whether the dose of furosemide was greater than or equal to 80 mg/day. METHODS: The primary measure was actual thiamine status as assessed by the erythrocyte transketolase enzyme activity and the degree of thiamine pyrophosphate effect. RESULTS: Biochemical evidence of severe thiamine deficiency was found in 98% (24 of 25) patients receiving at least 80 mg/day of furosemide and in 57% (four of seven) of patients taking 40 mg furosemide daily, odds ratio (OR) 19.0 (1.13<OR<601.29). Thiamine status was not associated with any other clinical variables. CONCLUSIONS: These findings suggest that thiamine deficiency occurs in a substantial proportion of congestive heart failure patients being treated with furosemide.

Aged↗
PubMed2002

The spectrum of intramyocardial small vessel disease associated with sudden death.

Intramyocardial small vessel abnormalities are not commonly recognized. The best known abnormality is fibromuscular dysplasia involving the sinoatrial or atrioventricular nodal arteries. Small vessel disease has been reported as an isolated cardiac anomaly in individuals with sudden death, and may also be associated with other cardiac conditions including hypertrophic cardiomyopathy and mitral valve prolapse. The nature of the association is unknown, and the mechanism causing sudden death is sometimes obscure. We describe pathological changes of the intramyocardial small vessels of three individuals with sudden death. Abnormalities involved small vessels at different levels. In all the cases, the abnormalities were thought to have caused or contributed to the individual's death. The possible mechanisms of this are discussed.

Adolescent↗