[QT interval dispersion analysis in acute myocardial infarction patients: coronary reperfusion effect]. / Análise da dispersão do intervalo QT em pacientes com infarto agudo do miocárdio: efeito da reperfusão coronariana.

OBJECTIVE: To study the effect of early reperfusion of infarct-related artery on QT(DeltaQT) dispersion interval, as well as how valuable it is as a marker for coronary reperfusion and ventricular arrhythmias. METHODS: One hundred and six patients with reperfusion (WR) and 48 without reperfusion (WtR) who have received thrombolytic therapy in the acute phase of infarction were studied. ECG carried out on admission as well as on day 4 of patients course were analyzed. DeltaQT - defined as the difference between maximum and minimum QT interval - was measured by 12-lead ECG. RESULTS: The reperfusion group showed significant DeltaQT reduction - from 89.66+/-20.47ms down to 70.95+/-21.65ms (p<0.001). On the other hand, the group without reperfusion showed DeltaQT significant increase - from 81.27+/-20.52ms up to 91.85+/-24.66ms (p<0.001). Logistic regression analysis showed that reduction magnitude between pre- and post-thrombolysis DeltaQT was the independent factor to most effectively identify coronary reperfusion (OR 1.045, p<0.0001; CI 95%). No significant difference was found in dispersion measures when patients with ventricular arrhythmias were compared with those with no arrhythmias in the course of the first 48 hours. CONCLUSION: The study shows that DeltaQT is significantly reduced in patients with acute myocardial infarction submitted to successful thrombolysis, and is increased in infarcted patients with closed artery. DeltaQT reduction between the pre- and post-thrombolysis condition was a predictor for coronary reperfusion of those patients, and did not show correlation to ventricular arrhythmias.

Energy cost of walking in boys who differ in adiposity but are matched for body mass.

PURPOSE: To compare the energy cost of treadmill walking, in pairs of obese and lean adolescents who were matched for total body mass. METHODS: Metabolic energy expenditure was determined at 67, 83, and 100 m.min-1, in nine obese and nine nonobese 11- to 18-yr-old boys. Total adiposity and fat distribution in the trunk and limbs were assessed using DXA. RESULTS: There were no intergroup differences in the net (exercise minus rest) energy cost at the two lower speeds, but the obese boys expended more energy at 100 m.min-1 (12%, P < 0.05). Heart rate was consistently higher in the obese boys: 18% at 67 m.min-1, 22% at 83 m.min-1, and 28% at 100 m.min-1. Pooling all subjects together, body mass, rather than adiposity, was the main predictor of energy cost: 89.1%, 76.3%, and 62.1% (P < 0.05 for all) of the total variance at 67, 83, and 100 m.min-1, respectively. The variance explained by total body fat was only 2.1%, 8.4%, and 16%, respectively. There was no relationship between [OV0312]O(2net) and the proportion of fat in body segments. CONCLUSION: It is total body mass, more than adiposity (total and regional) per se, that affects the energy cost of locomotion in obese boys.

Análise da dispersão do intervalo QT em pacientes com infarto agudo do miocárdio: efeito da reperfusão coronariana / QT interval dispersion analysis in acute myocardial infarction patients: coronary reperfusion effect

OBJETIVO: Estudar o efeito da reperfusão precoce da artéria relacionada ao infarto sobre a dispersão do intervalo QT(deltaQT), e seu valor como marcador de reperfusão coronária e de arritmias ventriculares. MÉTODOS: Foram avaliados 106 pacientes com reperfusão (CR) e 48 pacientes sem reperfusão (SR) que receberam terapia trombolítica na fase aguda do infarto. Foram analisados os eletrocardiogramas realizados na admissão e no 4° dia de evolução. A deltaQT, definido como a diferença entre o maior e o menor intervalo QT, foram medidos no ECG de 12 derivações. RESULTADOS: Na evolução do grupo com reperfusão, houve redução significativa da deltaQT de 89,66±20,47ms para 70,95±21,65ms (p<0,001). Por outro lado, no grupo sem reperfusão, houve aumento significativo da deltaQT de 81,27±20,52ms para 91,85±24,66ms (p<0,001). Análise de regressão logística demonstrou que a magnitude de redução entre a deltaQT pré e pós-trombólise foi o fator independente que identificou mais efetivamente a reperfusão coronária (OR 1,045, p<0,0001; IC 95 por cento). Não houve diferença significativa das medidas de dispersão quando comparados os pacientes que apresentaram arritmias ventriculares nas primeiras 48 h com aqueles sem arritmias. CONCLUSÃO: Esse estudo mostra que a deltaQT reduz significativamente em pacientes com infarto agudo do miocárdio submetidos à trombólise com sucesso, aumentando nos pacientes que evoluem com a artéria fechada. A redução deltaQT entre a situação pré e pós-trombólise foi fator preditor de reperfusão coronária nesses pacientes, não apresentando correlação com arritmias ventriculares.

O uso do teste ergométrico nas valvopatias / The use of exercise test in heart valvular disease

Os pacientes com valvopatias apresentam, na maioria das vezes, alterações da repolarização ventricular no eletrocardiograma de repouso, secundárias à própria valvopatia, limitando a indicação do teste ergométrico para diagnóstico de isquemia miocárdica induzida pelo esforço. Entretanto, o teste é de grande...