Maximal exercise capacity of children with heart defects

Area of Science:

• Pediatric Cardiology
• Exercise Physiology

Background:

• Assessing exercise capacity in children with heart defects is crucial for management.
• Normal reference values for exercise testing in children can vary significantly based on the control group used.

Purpose of the Study:

• To compare the exercise capacity of children with heart defects to normal values.
• To evaluate the influence of different control groups on exercise capacity assessments.
• To determine the utility of maximal exercise testing in differentiating heart defect severity.

Main Methods:

• Maximal treadmill tests using the Bruce protocol were conducted on 830 children with heart defects.
• Endurance times were compared to two control groups: 327 children with normal murmurs and 388 healthy school children.
• Maximal heart rates were recorded during testing.

Main Results:

• When using normal clinic children as controls, 21% of patients with heart defects had below-average endurance.
• Using healthy school children as controls revealed 47% of patients with heart defects had below-average endurance, with higher normal values observed in this group.
• Maximal heart rates were generally normal (180-210 bpm) in children with heart defects, except in cyanotic or severe valve disease cases.

Conclusions:

• The choice of a normal control group significantly impacts the interpretation of exercise capacity in children with heart defects.
• Children without heart defects seen in a clinic setting may be a more appropriate control group than healthy school children.
• Maximal exercise tests are not sensitive enough to distinguish between mild and severe heart disease, with significant reductions primarily seen in cyanotic or severe cases.