Pediatr Cardiol 11:227, 1990
Pediatric Cardiology 9 Springer-VerlagNew York Inc. 1990
Letters to the Editor Exercise in Sickle Cell Anemia I would like to dispute a major methodologic issue concerning the study by McConnell et al. [3]. The authors chose two exercise workloads, 30 and 70% of the maximal predicted capacity from normal subjects [2]. Studies in our laboratory have shown that the working capacities of children with sickle cell anemia are uniformly decreased [1]. We exercised 47 children on a cycle ergometer protocol and analyzed working capacity with respect to ischemia on the exercise ECG. The seven patients with definite ischemia on exercise had a mean maximal working capacity of 9.5 -+ 2.6 kg m/kg, 61% of the capacity predicted from laboratory controls. The 16 patients with equivocal ischemia had a mean working capacity value of 71% predicted, and those with no ischemia averaged 76% predicted. As we had described, McConnell's patients with the lowest hemoglobin levels had the highest incidence of exercise-induced ST-segment depression (ischemia). Many of the patients were not performing submaximal stress, as stated in the article, but rather were probably at their maximal levels, explaining the high incidence of exercise-induced ST-segment
change. With the advent of spectroscopic magnetic resonance techniques, it may now be possible to demonstrate myocardial high-energy phosphate metabolic changes with exercise and to define the physiologic significance of the observed ECG changes. Bruce S. Alpert Division of Pediatric Cardiology University o f Tennessee, Memphis Memphis, Tennessee, USA
References 1. Alpert BS, Gilman PA, Strong WB, Wilson MF, Miller MD, McFarlane J, Hayashidera T (1981) Hemodynamic and ECG responses to exercise in children with sickle cell anemia. Am J Dis Child 135:362-366 2. James FW, Kaplan S, Glueck CJ, Tsay J-Y, Knight MJS, Sarwar CJ (1980) Responses of normal children and young adults to controlled bicycle exercise. Circulation 61:902-912 3. McConnell ME, Daniels SR, Lobel J, James FW, Kaplan S (1989) Hemodynamic response to exercise in patients with sickle cell anemia. Pediatr Cardiol 10:141-144
Pediatric Cardiology 9 Springer-VerlagNew York Inc. 1990
Letters to the Editor Exercise in Sickle Cell Anemia I would like to dispute a major methodologic issue concerning the study by McConnell et al. [3]. The authors chose two exercise workloads, 30 and 70% of the maximal predicted capacity from normal subjects [2]. Studies in our laboratory have shown that the working capacities of children with sickle cell anemia are uniformly decreased [1]. We exercised 47 children on a cycle ergometer protocol and analyzed working capacity with respect to ischemia on the exercise ECG. The seven patients with definite ischemia on exercise had a mean maximal working capacity of 9.5 -+ 2.6 kg m/kg, 61% of the capacity predicted from laboratory controls. The 16 patients with equivocal ischemia had a mean working capacity value of 71% predicted, and those with no ischemia averaged 76% predicted. As we had described, McConnell's patients with the lowest hemoglobin levels had the highest incidence of exercise-induced ST-segment depression (ischemia). Many of the patients were not performing submaximal stress, as stated in the article, but rather were probably at their maximal levels, explaining the high incidence of exercise-induced ST-segment
change. With the advent of spectroscopic magnetic resonance techniques, it may now be possible to demonstrate myocardial high-energy phosphate metabolic changes with exercise and to define the physiologic significance of the observed ECG changes. Bruce S. Alpert Division of Pediatric Cardiology University o f Tennessee, Memphis Memphis, Tennessee, USA
References 1. Alpert BS, Gilman PA, Strong WB, Wilson MF, Miller MD, McFarlane J, Hayashidera T (1981) Hemodynamic and ECG responses to exercise in children with sickle cell anemia. Am J Dis Child 135:362-366 2. James FW, Kaplan S, Glueck CJ, Tsay J-Y, Knight MJS, Sarwar CJ (1980) Responses of normal children and young adults to controlled bicycle exercise. Circulation 61:902-912 3. McConnell ME, Daniels SR, Lobel J, James FW, Kaplan S (1989) Hemodynamic response to exercise in patients with sickle cell anemia. Pediatr Cardiol 10:141-144
