[Influence of posture on exercise-induced electrocardiographic and hemodynamic changes in patients with stable effort...

The present work was performed in order to assess the differences in electrocardiographic and hemodynamic responses to supine and upright dynamic exercise of patients with coronary artery disease. Changes in heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure, rate-pressure product (RPP) and ST segment depression during supine and upright bicycle stress test were compared in twenty patients suffering from stable effort angina and without previous myocardial infarction. In the supine posture lower values of HR were observed at rest, during stress test and during three minutes of the recovery period. Conversely, in all patients both SBP and DBP were higher during the stress test in the supine position decubitus. No significant changes in RPP was observed between the two different postures. Finally, ST segment didn't show differences at rest between the upright and supine position. All the patients had a lower ischemic threshold during exercise in the supine position than in the upright one. In fact an ST segment depression greater than 1 mm was observed during stress test in the supine position at lower work-load levels and at lesser HR values. Consequently for given HR, SBP and DBP ST segment, depression was greater in the supine rather than in the upright position.