Biomedical subjects

Paul A Gould

Publications and source records attributed to Paul A Gould.

11 recordsLinked to original sources

PubMed2006

Complications associated with implantable cardioverter-defibrillator replacement in response to device advisories.

CONTEXT: Recent implantable cardioverter-defibrillator (ICD) advisories and recalls have caused management dilemmas for physicians, particularly because there are no specific guidelines or data on outcomes from current management strategies. The risk of ICD generator replacement has not been assessed in this population. OBJECTIVE: To determine the complication rate associated with ICD generator replacement for the current ICD advisories. DESIGN AND SETTING: Seventeen ICD implanting centers in Canada were surveyed to assess complication rates as a result of generator replacements because of ICD advisories from October 2004 to October 2005. MAIN OUTCOME MEASURE: Complications associated with elective ICD generator replacement for current device advisories. RESULTS: At the 17 surveyed centers, 2915 patients had recall devices, including 533 (18.3%) who had advisory ICDs replaced a mean (SD) of 26.5 (11.5) months after their initial implant. Of these patients, 66% had a secondary prevention ICD, and 45% had received a previous appropriate shock. During a mean (SD) of 2.7 (2.8) months' follow-up after ICD generator replacement, complications occurred in 43 patients (8.1%). Major complications attributable to advisory device replacement requiring reoperation occurred in 31 patients (5.8%), with death in 2 patients after extraction for pocket infection. Minor complications occurred in 12 patients (2.3%). There were 3 (0.1%) advisory-related device malfunctions reported, without clinical consequences. CONCLUSIONS: ICD generator replacement in patients with advisory devices is associated with a substantial rate of complications, including death. These complications need to be considered in the development of guidelines determining the appropriate treatment of patients with advisory devices.

Aged↗

PubMed2006

Investigating syncope: a review.

PURPOSE OF REVIEW: This review focuses on recent literature on the cardiovascular investigation of syncope. RECENT FINDINGS: Syncope is a common and complex clinical entity with many varied etiologies, the diagnosis of which can often be elusive. Recent advances in the area of investigation in syncope include improvements in technologies for arrhythmia event monitoring and an increase in applicability and efficacy of traditional investigations. These advances have increased our ability to manage syncope. SUMMARY: A better understanding of the etiology of syncope in certain cohorts has allowed tailoring of investigations and management of syncope. This is evident when syncope occurs in the presence of structural heart disease, which is associated with a higher incidence of arrhythmias and an increased 1-year mortality. Patients with left-ventricular dysfunction should be considered candidates for an implantable cardioverter defibrillator based on heart function and syncopal presentation. In the absence of significant heart disease, investigations need to be tailored to diagnose neurally mediated causes for syncope and detection of intermittent bradycardia. The improved understanding of syncope has arisen from studies using improved investigational tools for syncope, in particular loop recorders, which are able to monitor cardiac rhythm over long periods. In those without structural heart disease and undifferentiated syncope, neurally mediated causes should be pursed initially. Tilt testing and loop recorders are employed most often in this cohort. Electrophysiological studies have largely been supplanted by implantable cardioverter defibrillator use in structural heart disease, with a low yield in patients with preserved heart function.

Cardiac Pacing, Artificial↗

PubMed2006

Evidence for increased atrial sympathetic innervation in persistent human atrial fibrillation.

OBJECTIVE: In this study, we aimed to compare the level of atrial sympathetic innervation in human atrial fibrillation (AF) to that in sinus rhythm (SR). BACKGROUND: Histological studies of atrial tissue obtained from animals with experimentally induced AF indicate that sympathetic hyperinnervation could play a role in the pathogenesis of AF. METHODS: In 24 patients (12 in SR and 12 in AF) undergoing bypass surgery, we collected right atrial appendage tissue. In AF patients, left atrial appendage tissue was also acquired. The degree of sympathetic innervation was quantified by measuring the amount of staining for tyrosine hydroxylase (TH) and tissue norepinephrine (NE). In conjunction, nerve growth factor (NGF) mRNA expression was assessed by real-time polymerase chain reaction (PCR). Growth-associated protein 43 (GAP43) immunostaining was used to assess degree of new neural growth. RESULTS: When corrected for differences in tissue fibrosis, the expression of both TH (AF 0.45 +/- 0.1%, SR 0.09 +/- 0.03%, P = 0.02) and tissue NE (AF 358 +/- 49 pg/mg, SR 225 +/- 39 pg/mg, P = 0.04) was greater in atrial tissue of the AF cohort. The degree of atrial TH staining (P = 0.01) and NE content (P < 0.001) was also significantly greater in the right compared with left atrial samples in the AF cohort. There were no differences in NGF mRNA expression or GAP43 staining. CONCLUSION: This study provides evidence for the presence of heightened atrial sympathetic innervation in patients with persistent AF, suggesting autonomic remodeling may be part of atrial substrate for AF.

Adaptation, Physiological↗

PubMed2006

The garden path.

Explore the source record for details and available documents.

Atrial Flutter↗

PubMed2006

Characteristics of slow pathway conduction after successful AVNRT ablation.

BACKGROUND: AV node slow pathway conduction can persist following successful ablation for AV node reentrant tachycardia (AVNRT). We hypothesized that careful examination of AV nodal conduction curves before and after effective AVNRT ablation in patients with persistent slow pathway conduction could shed light on this apparent paradox. METHODS AND RESULTS: Thirty patients (age 40.9 +/- 14.3; 8 male) were included. AV node function curves were created based on pre- and postablation atrial extrastimulus testing. Analysis of slow pathway function curves demonstrated significant decrease in AH for any given coupling interval after ablation (mean difference -68.1 [-94.5, -41.7] P < 0.001), graphically indicated by downward displacement of the curve. In addition, mean slow pathway effective refractory period (ERP) increased from 247.9 +/- 36.1 msec to 288.6 +/- 56.0 msec (P < 0.001); mean maximum AH interval decreased from 361.3 +/- 114.2 msec to 306.9 +/- 65.2 msec (P = 0.013); mean difference in minimum and maximum AH interval during slow pathway conduction decreased (from 94.5 +/- 75.8 msec to 59.6 +/- 46.2 msec (P = 0.016). Finally, mean difference between the fast and slow pathway effective refractory periods, the span of coupling intervals over which slow pathway conduction occurred, decreased (from 113.9 +/- 61.4 msec to 63.2 +/- 41.5 msec, P = 0.001). CONCLUSIONS: Ablation, which successfully eliminates inducible and spontaneous AVNRT in the presence of persistent slow pathway conduction, is associated with significantly altered slow pathway conduction characteristics, indicating the presence of a damaged or different slow pathway after ablation, incapable of sustaining tachycardia.

Adult↗

PubMed2006

Biventricular pacing in heart failure: a review.

Biventricular pacing has been an exciting recent advance in the management of drug-refractory heart failure. This new therapy has evolved as much from necessity as scientific observation, since benefits derived from pharmacotherapy currently appear to have reached their peak. Clinical trials of biventricular pacing are establishing morbidity and mortality benefits in heart failure. New challenges in the use of these pacemakers are now arising. These include the accurate diagnosis of ventricular dyssynchrony and, hence, potential responders to the refinement of implantation of the left ventricular lead to the appropriate dyssynchronous ventricular area and optimization of pacemaker programming. This review gives a general overview of the principles and the current evidence for the use of biventricular pacemakers in the treatment of heart failure. In addition, a discussion of current research and future projects is included.

Cardiac Pacing, Artificial↗

PubMed2005

Subacute anthracycline cardiotoxicity.

We describe the case of 25-year-old man, with acute myeloid leukaemia, who presented with a myopericarditis syndrome 17 days post consolidation chemotherapy with high dose cytarabine and idarubicin. Transthoracic echocardiography showed marked transient increased left ventricular wall thickness associated with normal systolic contraction. In conjunction, pulsed tissue Doppler analysis revealed low early diastolic annular velocities, consistent with diastolic dysfunction. Endomyocardial biopsy showed severe interstitial myocardial oedema in the absence of a cellular infiltrate or myofibre damage. We believe this is the first case of subacute anthracycline toxicity described with the pathological findings of isolated myocardial oedema.

Adult↗

PubMed2005

Atrial fibrillation impairs cardiac sympathetic response to baroreceptor unloading in congestive heart failure.

AIMS: In this study, we investigated for a potential mechanism by which atrial fibrillation (AF) might convey a worse prognosis in congestive heart failure (CHF). Specifically, we aimed to determine whether AF impaired cardiac sympathetic response to baroreceptor unloading in comparison to sinus rhythm (SR) in CHF. METHODS AND RESULTS: Eighteen CHF patients (ejection fraction 30+/-2%, age 59+/- 2 years), nine in SR and nine in AF, were enrolled. A right heart study and cardiac sympathetic tone assessment by coronary sinus catheter were performed at baseline and after 10 min of 20 degrees and 30 degrees of passive head up tilt (HUT). Filling pressures fell significantly during HUT in both SR and AF groups (AF, P=0.002; SR, P<0.001). The cardiac sympathetic response to HUT was significantly attenuated by AF compared with SR (P=0.014). In conjunction, right atrial appendages were collected from 23 cardiac surgery patients, 12 in SR and 11 in AF to investigate the presence of fibrosis. AF was associated with a significant increase in the collagen density (P=0.025). CONCLUSION: AF is associated with impaired cardiac sympathetic response to baroreceptor unloading compared with SR in CHF, possibly secondary to atrial fibrosis.

Atrial Fibrillation↗

PubMed2003

Chronic atrial fibrillation does not influence the magnitude of sympathetic overactivity in patients with heart failure.

AIMS: In this study we sought to assess the influence of atrial fibrillation (AF) on sympathetic nervous system overactivity in congestive heart failure (CHF) patients. METHODS AND RESULTS: We studied 133 consecutive patients with moderate to severe CHF. Subjects underwent haemodynamic assessment (right heart catheterization) and assessment of total systemic and cardiac sympathetic activity by the norepinephrine (NE) spillover method. The study population included 108 patients in sinus rhythm (SR) and 25 in AF. While AF patients had a lower cardiac output (CO) (SR vs AF: 4.2+/-0.1 vs 3.7+/-0.2l/min, P<0.05), the groups were otherwise matched for systemic blood pressure (BP), heart rate and filling pressures. In conjunction, total body NE spillover (SR vs AF: 5.8+/-0.4 vs 4.9+/-0.5 nmol/min, P>0.05) and cardiac NE spillover (SR vs AF: 339+/-21 vs 393+/-49 pmol/min, P>0.05) were not significantly different between the two groups, while the systemic clearance rate for NE was lower in the AF group (SR vs AF: 2.2+/-0.1 vs 1.6+/-0.1l/min, P<0.05). CONCLUSION: Congestive heart failure patients in AF do not appear to have heightened sympathetic tone compared to CHF patients in SR.

Atrial Fibrillation↗

PubMed2003

Review of the current management of atrial fibrillation.

Atrial fibrillation (AF) is the most common sustained arrhythmia. Its prevalence is increasing and accordingly, so is its burden on healthcare systems throughout the world. The pathophysiology of AF is complex and poorly understood, which of itself presents a major challenge to the management of this important condition. AF is associated with increased morbidity and mortality, particularly in patients with underlying left ventricular dysfunction. Once AF occurs, it is often difficult to 'cure' and as such, the major focus of therapy is currently divided essentially between a rate control strategy and a need to revert to and maintain sinus rhythm. Both approaches seek to minimise the associated symptoms and complications. Over the past two decades, numerous pharmacological approaches to the management of AF have been employed, many of which have been shown to be relatively ineffective or confounded by major complications. Accordingly, recent research and interest has focused on non-pharmacological electrophysiological therapies to either cure AF or improve symptoms. This review summarises the current approaches to the management AF and provides some new insights into emerging therapies for this common clinical problem.

Anti-Arrhythmia Agents↗

PubMed2002

Clinical treatment regimens for chronic heart failure: a review.

Chronic heart failure (CHF) is increasing in prevalence worldwide, particularly in the elderly. Accordingly, this epidemic is likely to translate into a major increase in healthcare costs. Systolic heart failure is the most common cause of CHF presentations. Although the causes vary, the most common single aetiological factor is ischaemic heart disease, which accounts for approximately 50% of heart failure presentations. Research into CHF pharmacotherapy has been copious, with the focus principally centred on systolic heart failure. The evidence base for pharmacotherapy in CHF is amongst the largest currently in clinical medicine. There have been multiple trials establishing the mortality and morbidity benefits of pharmacotherapy. Amongst these, large scale trials of angiotensin-converting enzyme inhibitors, beta-blockers and spironolactone have provided a sound basis for evidence-based treatment approaches to the CHF patient. Recently research interest has increased in biomedical engineering with studies being performed in biventricular pacing and mechanical hearts. Early data with biventricular pacing or cardiac resynchronisation therapy is encouraging. Diastolic heart failure alone accounts for at least 20 - 40% of CHF presentations and whilst it may occur in isolation, is most commonly seen in association with systolic heart failure. In this study, we present a broad overview of the current therapeutic modalities for the management of CHF, with particular emphasis on pharmacotherapy.

Adrenergic beta-Antagonists↗