RESUMO
BACKGROUND: The warm-up phenomenon observed after the second of two sequential exercise tests is characterized by an increased time to ischemia and ischemic threshold, and the latter is related to ischemic preconditioning. Previous studies have demonstrated that a single dose of glibenclamide, a cardiac ATP-sensitive K (K(ATP)) channel blocker, prevents ischemic preconditioning. This study aimed to investigate the effects of chronic treatment with glibenclamide during two sequential exercise tests. METHODS: Forty patients with angina pectoris were divided into three groups: 20 nondiabetics (NDM), 10 patients with diabetes in treatment with glibenclamide (DMG) and 10 diabetic patients with other treatments (DMO). All patients underwent two consecutive exercise tests. RESULTS: Heart rate and rate-pressure product at 1.0 mm ST-segment depression significantly increased during the second exercise test in NDM group (121.3+/-16.5 vs 127.3+/-15.3 beats/min, P<0.001, and 216.7+43.1 vs 232.1+/-43.0 beats.min-1.mmHg.10(2), P<0.001), and in DMO group (114.1+/-19.6 vs 119.6+/-18.1 beats/min, P=0.001, and 199.8+/-36.6 vs 222.2+/-29.2 beats.min-1.mmHg.10(2), P=0.019), but it did not change in patients in DMG group (130.7+/-14.5 vs 132.1+/-4.7 beats/min, P=ns, and 251.7+/-47.2 vs 250.3+/-42.8 beats.min-1.mmHg.10(2), P=ns). In the three groups, NDM, DMO, and DMG, the time to 1.0 mm ST-segment depression during the second exercise test was greater than during the first (225.0+/-112.5 vs 267.0+/-122.3 seconds, P=0.006; 187.5+/-54.0 vs 226.5+/-74.6 seconds, P=0.029 and 150.0+/-78.7 vs 186.0+/-81.9 seconds, P<0.001). CONCLUSION: The chronic use of glibenclamide may have mediated the loss of preconditioning benefits in the warm-up phenomenon, probably through its KATP channel-blocker activity, but without acting upon the tolerance to exercise.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Teste de Esforço , Glibureto/uso terapêutico , Hipoglicemiantes/uso terapêutico , Precondicionamento Isquêmico Miocárdico/métodos , Análise de Variância , Angina Pectoris/fisiopatologia , Distribuição de Qui-Quadrado , Doença Crônica , Angiografia Coronária , Doença da Artéria Coronariana/fisiopatologia , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/fisiopatologia , Eletrocardiografia/efeitos dos fármacos , Feminino , Humanos , MasculinoRESUMO
PURPOSE--To describe groups of patients who have obstructive and non-obstructive coronary artery disease, through computadorized exercise stress test. METHODS--The test was done in 121 patients, all male, divided into 3 groups: GN group, 50 patients with normal electrocardiographic response to exercise; GLO group, 40 patients with obstructive coronary artery disease and GNO group, 31 patients with normal coronary arteries, showing one or more of the following entities: intramural coronary traject, coronary tortuosity, slow flow, mitral valve prolapse or left ventricular hypertrophy. GLO and GNO groups presented with abnormal response of the ST segment during exercise. The quantitative variables registered by computer were particularly analyzed as follows: STL (point Y depression), slope, index and ST segment integral. The magnitude of ST vector was visually measured and quantified. The statistic study was made through ANOVA and multiples comparison by the Scheffe's method, Fisher's test, quisquare and sensibility, specificity and accuracy calculation. RESULTS--There was a significant statistic difference among the 3 groups relative to slope and index (p < 0.05). The integral variable of ST segment did not allow us to differentiate the GLO and GNO groups. In the association study between the ST vector magnitude and abnormal T loop, there was an increase in sensibility of 15//in the exercise stress test. CONCLUSION--The ST segment slope below zero values, define patients having obstructive disease, and the opposite, non-obstructive disease. Values of ST segment index lower than -2 are linked to obstructive disease and higher than -2 linked to non-obstructive. Values of ST segment lower than -7 microV. s separate individuals with normal exercise stress test from those with ischemic type response. The magnitude of ST vector equal to or lower than 0.20mV define normal vectorcardiographic response to the exercise
Assuntos
Humanos , Masculino , Adulto , Pessoa de Meia-Idade , Arteriopatias Oclusivas/diagnóstico , Diagnóstico por Computador , Isquemia Miocárdica/diagnóstico , Teste de Esforço , Arteriopatias Oclusivas/complicações , Diagnóstico Diferencial , Isquemia Miocárdica/etiologia , VetorcardiografiaRESUMO
An 8 year old child suffering from asthenia and complete atrioventricular block, probably congenital. During the tread-mill test there was a sudden electrocardiogram change to a ventricular preexcitation pattern. Besides this rare association, we emphasize the importance of the autonomic balance over the accessory pathway's electrophysiological properties. The appearance of a latent accessory pathway might be a substitutive mechanism to counterbalance the serious impairment of physiologic atrioventricular conduction