Low-dose Epinephrine Infusion Tests in Adolescent and Pediatric Patients

Long QT syndrome (LQTS)is a cardiac disorder that may lead to ventricular arrythmias and culminate in syncope and/or possible death. Recently, researchers have developed a way of discovering patients with LQTS by using low doses of epinephrine by a continuous, intravenous infusion in adults. Epinephrine, or adrenaline, is produced by our bodies in times of stress. By producing adrenaline, your body allows itself to adapt to its stressful environment and take appropriate actions (i.e. fight or flight response). By simulating this response with very small amounts of epinephrine, researchers have shown prolongation of the QT interval does not occur in normal healthy adults. However, adults with confirmed LQTS Type 1 (LQTS-1) will prolong their QT interval when given low dose epinephrine. Therefore, this test can act as a safe means of identifying adults with LQTS-1 who do not have prolonged QT intervals on their resting EKGs. However, LQTS is not just a disease of adults, it affects children as well. Currently the standard of care is to obtain resting EKGs on our pediatric patients which can miss those patients with concealed LQTS. Those patients, who are old enough, can undergo exercise testing. Yet this leaves young children unable to run on a treadmill without a diagnostic test. Hypothesis: The low-dose epinephrine infusion stress test does not cause prolongation of the QT interval in an electrophysiologically normal healthy pediatric population.