[The usefulness of the application of nonlinear dynamics in the analysis of electrocardiograms in Chagas' disease patients]. / Utilidad de la aplicación de técnicas de modelado no lineal en el análisis de electrocardiogramas de pacientes con infección chagásica.

INTRODUCTION AND OBJECTIVES: The application of nonlinear techniques allows the definition of early risk markers in patients with Chagas infection and without any evidence of cardiac involvement evaluated by standard diagnostic test. Nonlinear modeling techniques have proved to be effective in cardiac rhythm analysis, thereby justifying its use in Chagas' disease. PATIENTS AND METHOD: The routine noninvasive test and heart rate variability analysis were performed in Chagas' disease patients and in a group of healthy subjects. In a second phase we used nonlinear analysis in the evaluation of patients with Chagas infection and no evidence of heart disease, Chagasic patients with minimal electrocardiographic abnormalities and healthy controls. RESULTS: Twenty-four-hour electrocardiographic ambulatory monitoring and heart rate variability allowed us to establish differences between the healthy subjects and patients with Chagas infection without evidence of cardiac disease (p c 0.05 and p <0.005). In sharp contrast nonlinear analysis characterized 4 subgroups in Chagasic patients without cardiac involvement (sensitivity and specificity of 1 00%). CONCLUSIONS: Our findings suggest that nonlinear modeling techniques have a high sensitivity and specificity in the early detection of cardiac involvement and very early autonomic disturbance. We recommend that these techniques be applied to patients with high risk of cardiac disease other than Chagasic myocarditis. Our findings should be corroborated with studies in larger populations. We are currently developing a prospective study to this end.

A double-blind, controlled, multicenter, randomized study comparing the antihypertensive effectiveness and tolerance of a daily dose of two nifedipine formulations: nifedipine microgranules versus nifedipine osmotic pump.

INTRODUCTION: Controlled clinical studies have clearly established the advantages of blood pressure (BP) reduction. However, optimal control of BP in the population is still not adequate. Monotherapy is ineffective in the majority of hypertensive patients, and multidrug therapy increases costs. OBJECTIVE: The objective of the study was to assess to what extent and how uniformly BP can be controlled with two different 24-hour drug-releasing formulations of nifedipine, used as monotherapy. METHODS: One hundred ninety-two patients of both genders, aged 18 to 65 years, with mild to moderate (Stage 1 and 2) essential hypertension with systolic BP <200 mm Hg and diastolic BP between 90 and 115 mm Hg were randomized in a double-blind, double-dummy fashion to receive sustained-release formulations of 30 mg nifedipine/day either as microgranules (NMG) or via osmotic pump (NOP) for 8 weeks. Office BP was measured at baseline (after 2 weeks of placebo) and after the third to fourth week of treatment. If at the third to fourth week the systolic BP/diastolic BP did not reach values of <140/<90 mm Hg, the dose was doubled to 60 mg/day. Monotherapy that did not yield these BP values at 8 weeks was considered a failure. Ambulatory monitoring of blood pressure (AMBP) was also performed after the placebo period and at the end of treatment. Smoothness index (SI) and trough/peak ratio (T/P) were calculated and their correlation was checked. RESULTS: The initial systolic/diastolic BP values were similar at baseline and decreased significantly after the third to fourth week of treatment, with no difference between the groups. The proportions of patients reaching the goal BP (<140/<90 mm Hg) were similar in the two groups: NMG, 71%, and NOP, 78% (P = 0.12). There were no changes in the heart rate in either group. There was no difference between groups in the reduction in mean arterial pressure measured by AMBP. The frequency of SI values >1.4 and T/P ratios of >0.5 was similar in both groups. An important correlation was found between the SI and T/P values. The incidence of adverse effects was low and similar in both groups. CONCLUSIONS: Target BP was reached in more than 70% of patients receiving monotherapy with either formulation. Both formulations were tolerated well.

Ruptura espontánea de aorta ascendente / Spontaneous rupture of the ascending aorta

Se presenta el caso de un paciente de 71 años, con una insuficiencia severa de Válvula Aórtica, que ameritó un Reemplazo Valvular Aórtico y 36 horas más tarde presenta una ruptura espontánea de Aorta Ascendente, la cual es tratada exitosamente