This is an excerpt from Cardiopulmonary Exercise Testing in Children and Adolescents by Thomas Rowland, American College of Sports Medicine & North American Society for Pediatric Exercise Medicine (NASPEM).
Rebecca is a 17-year-old varsity cross country runner whom you have followed in your pediatric practice since she was a young child. She presents to you today with complaints of multiple episodes of dizziness with exertion, the first event having started approximately 1 yr ago. She describes the dizziness as "spinning," and it occurs not during running but just after she has finished. It usually occurs after running at a high-tempo pace for several miles and usually in the summer months. She denies frank syncope, chest pain, shortness of breath, or palpitations. There was a documented blood pressure of 62/40 at one time when paramedics were called while the event was occurring. She has been seen in the emergency room twice for the complaint; the most recent was 2 d ago. In the emergency room, she had a normal heart rate and blood pressure, normal physical examination, and normal laboratory values for anemia and thyroid. Her chest radiograph and electrocardiogram (ECG) were unremarkable. She has been restricted from exercise until she is seen by you. She is requesting exercise clearance.
Turning back to our case study, on further questioning it is revealed that Rebecca drinks 20 oz of water daily and one cup of coffee in the morning. She often skips breakfast as well because she does not have time to eat. She sometimes experiences dizziness in the morning when she stands up while getting out of bed. Rebecca's physical examination included orthostatic vital signs. Her heart rate increased from 52 bpm supine to 90 bpm in the upright position. Her blood pressure decreased from 116/68 to 108/64 from supine to upright position, respectively. Her physical examination was otherwise unremarkable.
Rebecca had an ECG performed, which was normal. Although her symptoms were classic for dehydration as well as a vasovagal component, because she was a competitive athlete, the cardiologist opted for an echocardiogram, which was normal, and an exercise stress test to try to induce her symptoms.
Rebecca performed a maximal treadmill exercise stress test. She had a high-normal aerobic capacity. There were no arrhythmias or ischemic changes. There was a normal heart rate and blood pressure response to exercise. She developed dizziness in early recovery with a 30 mmHg drop in her blood pressure. After she drank a cup of water and was placed in the supine position, her blood pressure improved within 2 min.
For Rebecca, her history, physical examination, and ECG were reassuring that this was unlikely to be cardiac-related exertional syncope. Her exercise stress test was able to document dizziness associated with a drop in blood pressure that responded to fluids and supine positioning. She was counseled on improving her hydration and salt intake and not to skip meals. She returned for a follow-up visit 3 mo later and had not experienced any further dizziness or syncope.
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