Clinical characteristics and outcome of lone atrial fibrillation at a tertiary referral centre: the Groote Schuur Hospital experience.

INTRODUCTION: Atrial fibrillation (AF) is a relatively common arrhythmia. When AF represents an electrophysiological phenomenon in structurally normal hearts, it is termed lone AF. This study was a retrospective, case-based analysis of patients attending the Cardiac Clinic at Groote Schuur Hospital (GSH) and describes the clinical characteristics and outcomes of patients classified as having lone atrial fibrillation. To the best of our knowledge there are no such studies reported from Africa. METHODS: This was a retrospective, descriptive study in which 289 medical records of patients with AF at the GSH Cardiac Clinic were reviewed from 1992 to 2006. The clinical data were interrogated to exclude identifiable causes of AF. Information on clinical characteristics and outcomes were entered into a data-entry form. Baseline descriptive statistics were expressed as means and range for continuous variables, and counts with percentages for categorical variables. RESULTS: Fifteen per cent (n = 42) of patients were identified as having lone AF, with a mean follow-up time of 5.8 years. Males comprised 57% (n = 24) and females 43% (n = 18). Fifty per cent (n = 21) of the patients had paroxysmal AF, 29% (n = 12) had persistent AF, and 12% (n = 5) progressed from paroxysmal to permanent AF. Subsets of lone AF included concomitant atrial flutter (17%) (n = 7) and sick sinus syndrome (21%) (n = 9). Complications were stroke (10%) (n = 4), tachycardia-related cardiomyopathy (17%) (n = 7) and bleeding complications on warfarin (11%) (n = 3). CONCLUSIONS: Lone AF is not an uncommon arrhythmia, with a preponderance in thin, middle-aged males. The symptoms of lone AF can be debilitating. It has associated morbidity, including tachycardia-related cardiomyopathy and thromboembolism. Rate control and appropriate anticoagulation are the cornerstones of patient management.

Clinical utility of B-type natriuretic peptide (NP) in pediatric cardiac surgery--a systematic review.

BACKGROUND: NP is a biomarker that has been used in the diagnosis, management, and prognostication of a number of cardiovascular disorders in the pediatric population. The physiological role of this hormone is to allow the myocardium to adapt to stress or strain imposed by a volume and/or pressure load. OBJECTIVE: The aim of this study was to determine the utility of preoperative and postoperative NP to predict outcome in pediatric patients undergoing cardiac surgery for structural congenital heart disease. METHOD: We conducted a systematic review by searching three electronic databases using the search terms 'paediatric' or 'pediatric' and 'B-type natriuretic peptide'. Twenty peer-reviewed papers were included in the study. RESULTS: Preoperative NP levels were associated with the severity of cardiac failure in several studies. Preoperative NPs also correlated with early postoperative outcome measures such as duration of cardiopulmonary bypass, duration of mechanical ventilation, presence of low cardiac output syndrome, length of stay in the intensive care unit and in one study, death. Early (within 24 h) postoperative NPs showed a stronger correlation than preoperative NPs to early postoperative adverse events. CONCLUSION: NPs provide a simple, noninvasive and complementary tool to echocardiography that can be used to assist clinicians in the assessment and management of pediatric patients with congenital heart disease in the perioperative period.

Exploring the pharmacokinetics of oral ketamine in children undergoing burns procedures.

AIMS: The aim of this study was to describe ketamine pharmacokinetics when administered orally to children suffering from burn injury in >10% body surface area. METHODS: Children (n = 20) were given ketamine 5 or 10 mg·kg(-1) orally 20 min prior to presentation for surgical procedures. Anesthesia during procedures was maintained with a volatile anesthetic agent. Additional intravenous ketamine was given as a bolus (0.5-1 mg·kg(-1)) to nine children during the procedure while a further nine children were given an infusion (0.1 mg·kg(-1)·h(-1)) continued for 4-19 h after the procedure. Blood was assayed for ketamine and norketamine on six occasions over the study duration of 8-24 h. Data were pooled with those from an earlier analysis (621 observations from 70 subjects). An additional time-concentration profile from an adult given oral ketamine was gleaned from the literature (17 observations). A population analysis was undertaken using nonlinear mixed-effects models. RESULTS: The pooled analysis comprised 852 observations from 91 subjects. There were 20 children who presented for procedures related to burns management (age 3.5 sd 2.1 years, range 1-8 years; weight 14.7 sd 4.9 kg, range 7.9-25 kg), and these children contributed 214 ketamine and norketamine observations. A two-compartment (central, peripheral) linear disposition model fitted data better than a one-compartment model. Bioavailability of the oral formulation was 0.45 (90% CI 0.33, 0.58). Absorption half-time was 59 (90% CI 29.4, 109.2) min and had high between-subject variability (BSV 148%). Population parameter estimates, standardized to a 70-kg person, were central volume 21.1 (BSV 47.1%) l·70 kg(-1), peripheral volume of distribution 109 (27.5%) l·70 kg(-1), clearance 81.3 (46.1%) l·h(-1)·70 kg(-1), and inter-compartment clearance 259 (50.1%) l·h(-1)·70 kg(-1). Under the assumption that all ketamine was converted to norketamine, the volume of the metabolite was 151.9 (BSV 39.1%) l·70 kg(-1) with an elimination clearance of 64.4 (BSV 63.4%) l·h(-1) ·70 kg(-1) and a rate constant for intermediate compartments of 26.2 (BSV 52.1%) h(-1)·70 kg(-1). CONCLUSIONS: The ketamine pharmacokinetics in children with minor burns are similar to those without burns. The peak ratio of norketamine/ketamine at 1 h is 2.8 after oral administration allowing an analgesic contribution from the metabolite at this time. There is low relative bioavailability (<0.5) and slow variable absorption. Dose simulation in a child (3.5 years, 15 kg) suggests a dose regimen of oral ketamine 10 mg·kg(-1) followed by intravenous ketamine 1 mg·kg(-1) i.v. with the advent of short-duration surgical dressing change at 45 min.