Dilatación de la arteria humeral mediada por flujo en varones sanos, con factores de riesgo e infarto agudo de miocardio. Importancia de la posición del manguito oclusor

Introduction and objectives. Flow-mediated dilation (FMD) is endothelium-dependent and can be assessed by ultrasound in the brachial artery. We sought to determine the most suitable position for the occlusion cuff for the study of FMD in three groups of adult men. Subjects and methods. We included 160 subjects, mean age 58.5 ± 7.8 years: 40 healthy subjects, 80 with cardiovascular risk factors, and 40 patients with AMI. In a subgroup of 60 subjects, the first 10, 30, and 20 of each group, respectively, FMD was evaluated twice, after upper arm occlusion and forearm occlusion to induce hyperemia. Results. In the initial substudy, the FMD after upper arm occlusion was 7.6 ± 2.4% in healthy subjects, 5.1 ± 2.2% in men with risk factors (p < 0.0001), and 3.5 ± 2.2% in AMI patients (p < 0.041, with respect to the risk-factor group). FMD after forearm occlusion was 4.6 ± 1.5%, 2.3 ± 2.1% (p < 0.006), and 2.2 ± 1.9%, respectively, with no significant statistical differences between the risk-factor and AMI groups. Only upper arm occlusion was performed in the remaining participants, as planned, because it provided the most accurate information. Overall, the FMD was, respectively, 7.8 ± 3.1%, 5 ± 2.6% (p < 0.0001) and 3.3 ± 3% (p < 0.004, with respect to the risk-factor group). FMD was directly related to HDL cholesterol and inversely related to resting diameter and number of risk factors. Conclusion. The best approach to studying FMD is proximal occlusion since it allows for a better stratification of men with endothelial dysfunction. With this technique, a worsening of endothelial function in acute myocardial infarction can be demonstrated.