Maximal voluntary work and cardiorespiratory fitness in patients who have had Kawasaki syndrome.

To assess the natural history of Kawasaki syndrome and its effect on maximal voluntary work and cardiorespiratory fitness, we performed cycle ergometry testing in 47 patients who had had the syndrome. Forty-one patients performed maximal effort as judged by achievement of 95% predicted heart rate response. Oxygen consumption, carbon dioxide production, and minute ventilation were performed in 23 patients. There was no difference in maximal voluntary work (total work, mean power) or maximal oxygen consumption between case subjects and control subjects. There were no differences between patients with and those without aneurysms. Serial exercise studies were performed in 10 patients; of these, two with initially normal exercise study findings had decreased maximal voluntary work and oxygen consumption with ischemic changes, and both were at high risk for the development of stenotic or occlusive coronary arteries. The other eight patients had normal cardiorespiratory reserve and no ischemic changes with serial studies. These results suggest that patients have normal cardiorespiratory fitness after Kawasaki syndrome. With the development of ischemic heart disease, they may have decreased cardiorespiratory reserve. Serial evaluation of cardiorespiratory fitness may demonstrate ischemic heart disease.

Normal aerobic and anaerobic exercise data for North American school-age children.

The purpose of this study was to establish normative data for untrained, healthy North American children by means of the James protocol for bicycle ergometry. Data were obtained on 151 of 185 children (70 girls and 81 boys). Their ages ranged from 7 years 6 months to 12 years 9 months. All subjects were divided into groups by gender and body surface area (BSA). Maximum heart rates were greater in girls. The mean difference between maximum and recovery heart rates differed significantly by gender, girls taking longer to recover than boys. Maximum oxygen consumption (measured in cubic centimeters per minute per kilogram body weight) did not differ in boys and girls. Ventilatory anaerobic threshold (VAT) occurred when there was an isolated increase in the slope for ventilatory equivalent for oxygen consumption (VE/VO2) with no change in the slope for ventilatory equivalent for carbon dioxide production (VE/VCO2) when both were plotted against time. Absolute oxygen consumption (VO2) at VAT increased with BSA in both sexes, and, when normalized to body size and expressed as a percent of VO2 maximum, no significant difference was observed between the sexes. These data may be used in the fitness evaluations of preadolescent children from North America.

The natural history of hypertrophic cardiomyopathy in infants of diabetic mothers.

Eleven infants of diabetic mothers with hypertrophic cardiomyopathy have been followed for 30 to 40 months. All infants presented with cardiorespiratory distress and were found to have disproportionate septal hypertrophy on echocardiogram. Cardiac catheterization was done in four infants; three had significant subaortic obstruction. One infant had remarkable improvement after treatment with propranolol. Two infants who received digoxin did poorly and responded favorably to cessation of therapy. The natural history of HCM-IDM appears to be benign, with a resolution of symptoms within two to four weeks and a resolution of septal hypertrophy within two to 12 months. Most of the infants need only supportive care; if pharmacologic intervention is deemed necessary, propranolol appears to be the drug of choice. The natural history of this entity is that of spontaneous regression of symptoms and septal hypertrophy irrespective of therapy.

The silent ductus arteriosus.

Preterm infants at risk of developing a patent ductus arteriosus were followed sequentially by physical examination, echocardiographic determinations of the LA/AO ratio, and chest roentgenograms. The results show that a significant number of infants who have no clinical signs or symptoms of a PDA have large left-to-right shunts. The presence of this shunt was suggested by acute increase in left atrial size by ECHO determination and confirmed by retrograde single-film aortography. Clinical signs and symptoms often developed several days after documentation of the left-to-right shunt.