Study objective: To determine and compare the
cardiopulmonary responses of healthy children and children with heart
failure due to idiopathic dilated cardiomyopathy (IC) to progressive
treadmill exercise testing.
teaching hospital specializing in cardiology.
participants: Twenty-six children with stable, chronic heart
failure (left ventricular ejection fraction < 45%) caused by IC (IC
group) and 12 healthy children (control group).
Interventions: After 12-lead resting ECG, all children
underwent progressive treadmill exercise testing using a modified
Naughton protocol. Tests were performed in a controlled-temperature
exercise facility, at least 2 h after a light meal.
Measurements and results: Cardiopulmonary parameters were
assessed at rest, at anaerobic threshold (AT), and at peak exercise. At
rest, the tidal volume (Vt) and O2 consumption
(V̇o2) for heart rate (O2
pulse) were lower, while the heart rate, respiratory rate, and
ventilatory equivalent for O2 (minute ventilation[
V̇e]/V̇o2) were higher
in the IC group compared with the control group. At AT, the systolic
BP, O2 pulse, Vt, exercise duration,
V̇o2, CO2 production
(V̇co2), and V̇e were
lower, while the V̇e/V̇o2
and ventilatory equivalent for CO2
(V̇e/V̇co2) were higher
in the IC group (p < 0.05). At peak exercise, the IC group had a
significantly lower systolic BP, O2 pulse,
V̇e, Vt, exercise duration,
V̇co2, but higher
V̇e/V̇co2 than the
control group (p < 0.05). The
V̇e/V̇co2 slope was
significantly higher for the IC group. No correlation existed between
variables evaluated at rest vs during exercise.
Conclusions: Gas exchange analysis performed during
exercise successfully differentiated children with heart failure from