Leandro Ioschpe Zimerman

Intrinsic sinus and atrioventricular node electrophysiologic adaptations in endurance athletes.

OBJECTIVES In the present study, we evaluated sinus and atrioventricular (AV) node electrophysiology of endurance athletes and untrained individuals before and after autonomic pharmacologic blockade. BACKGROUND Endurance athletes present a higher prevalence of sinus bradycardia and AV conduction abnormalities, as compared with untrained individuals. Previous data from our laboratory suggest that nonautonomic factors may be responsible for the longer AV node refractory period found in well-trained athletes. METHODS Six aerobically trained male athletes and six healthy male individuals with similar ages and normal rest electrocardiograms were studied. Maximal oxygen uptake (O(2)max) was measured by cardiopulmonary testing. The sinus cycle length (SCL), AV conduction intervals, sinus node recovery time (SNRT), Wenckebach cycle (WC) and anterograde effective refractory period (ERP) of the AV node were evaluated by invasive electrophysiologic studies at baseline, after intravenous atropine (0.04 mg/kg) and after addition of intravenous propranolol (0.2 mg/kg). RESULTS Athletes had a significantly higher O(2)max as compared with untrained individuals. The SCL was longer in athletes at baseline, after atropine and after the addition of propranolol for double-autonomic blockade. The mean maximal SNRT/SCL was longer in athletes after atropine and after propranolol. The WC and anterograde ERP of the AV node were longer in athletes at baseline, after atropine and after propranolol. CONCLUSIONS Under double-pharmacologic blockade, we demonstrated that sinus automaticity and AV node conduction changes of endurance athletes are related to intrinsic physiology and not to autonomic influences.

Atrial automaticity and atrioventricular conduction in athletes: contribution of autonomic regulation

Abstract Little is known about the sinoatrial automatism and atrioventricular conduction of trained individuals who present a normal resting electrocardiogram. We used transesophageal atrial stimulation, a minimally invasive technique, to evaluate aerobically trained athletes (n=10) and sedentary individuals (n=10) with normal resting electrocardiograms, to test the hypothesis that parasympathetic tone, as detected by heart rate variability, could be associated with changes in sinoatrial automatism and atrioventricular conduction. Corrected sinus node recovery time tended to be longer in athletes than in sedentary individuals, but this difference did not reach statistical significance. The Wenckebach point occurred at a lower rate in athletes than in the controls. Over a 24-h period of measurement, the mean RR interval was longer in the athletes than in the sedentary individuals. The mean square root of successive differences (rMSSD) tended to be higher in athletes than in controls, but this difference did not reach statistical significance. There was a moderate correlation (r=0.48, P < 0.05) between the index of atrioventricular conduction, the rate at the Wenckebach point, and the logarithmically transformed rMSSD. Thus, as a corollary to its effects on the sinus node, where increased parasympathetic tone, decreased sympathetic tone, and non-autonomic components may contribute to sinus bradycardia, it is possible that athletic training may also induce intrinsic adaptations in the conduction system, which could contribute to the higher prevalence of atrioventricular conduction abnormalities observed in athletes.

Cost-Effectiveness of Implantable Cardioverter-Defibrillators in Brazil: Primary Prevention Analysis in the Public Sector

BACKGROUND Several studies have demonstrated the effectiveness and cost-effectiveness of implantable cardioverter-defibrillators (ICDs) in chronic heart failure (CHF) patients. Despite its widespread use in developing countries, limited data exist on its cost-effectiveness in these settings. OBJECTIVE To evaluate the cost-effectiveness of ICD in CHF patients under the perspective of the Brazilian Public Healthcare System (PHS). METHODS We developed a Markov model to evaluate the incremental cost-effectiveness ratio (ICER) of ICD compared with conventional therapy in patients with CHF and New York Heart Association class II and III. Effectiveness was evaluated in quality-adjusted life years (QALYs) and time horizon was 20 years. We searched MEDLINE for clinical trials and cohort studies to estimate data from effectiveness, complications, mortality, and utilities. Costs from the PHS were retrieved from national administrative databases. The models robustness was assessed through Monte Carlo simulation and one-way sensitivity analysis. Costs were expressed as international dollars, applying the purchasing power parity conversion rate (PPP US

Custo-efetividade de cardiodesfibriladores implantáveis no Brasil nos setores público e privado

). RESULTS ICD therapy was more costly and more effective, with incremental cost-effectiveness estimates of PPP US

Genetic polymorphisms of the adrenergic system and implantable cardioverter-defibrillator therapies in patients with heart failure

50,345/QALY. Results were more sensitive to costs related to the device, generator replacement frequency and ICD effectiveness. In a simulation resembling the MADIT-I population survival and ICD benefit, the ICER was PPP US

Effect of caffeine on ventricular arrhythmia: a systematic review and meta-analysis of experimental and clinical studies

17,494/QALY and PPP US

Short-term Effects of High-Dose Caffeine on Cardiac Arrhythmias in Patients With Heart Failure: A Randomized Clinical Trial

15,394/life years. CONCLUSIONS In a Brazilian scenario, where ICD cost is proportionally more elevated than in developed countries, ICD therapy was associated with a high cost-effectiveness ratio. The results were more favorable for a patient subgroup at increased risk of sudden death.

Acute electrophysiologic consequences of pyridostigmine inhibition of cholinesterase in humans

BACKGROUND: Many randomized clinical trials have demonstrated the effectiveness of the implantable cardioverter-defibrillator (ICDs) in death reduction of chronic heart failure (CHF) patients. Some developed countries studies have evaluated its cost-effectiveness, but these data are not applicable to Brazil. OBJECTIVE: To evaluate the cost-effectiveness of ICD in CHF patients under two perspectives in Brazil: public and supplementary health systems. METHODS: A Markov model was developed to analyze the incremental cost-effectiveness ratio (ICER) of ICD compared to conventional therapy in patients with CHF. Effectiveness was measured in quality-adjusted life years (QALYs). We searched the literature for data regarding effectiveness and complications. Costs were retrieved from public and health insurances reimbursement codebooks and from mean cost of admissions from a public and a private hospital. One-way sensitivity analysis was performed in all variables of the model. RESULTS: ICER was R

Anestesia venosa total com infusão alvo-controlada de remifentanil e propofol para ablação de fibrilação atrial

68,318/QALY in the public and R

Total intravenous anesthesia with target-controlled infusion of remifetanil and propofol for ablation of atrial fibrillation

90,942/QALY in the private perspective. These values are much higher than the one suggested by the World Health Organization of 3 times the gross domestic product per head (R