Cardiopulmonary Exercise Testing in Children With Heart Failure Secondary to Idiopathic Dilated Cardiomyopathy

Abstract

Study objectiveTo 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. SettingUniversity teaching hospital specializing in cardiology. Patients or participantsTwenty-six children with stable, chronic heart failure (left ventricular ejection fraction < 45%) caused by IC (IC group) and 12 healthy children (control group). InterventionsAfter 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 resultsCardiopulmonary parameters were assessed at rest, at anaerobic threshold (AT), and at peak exercise. At rest, the tidal volume (Vt) and O2 consumption (▪o2) for heart rate (O2 pulse) were lower, while the heart rate, respiratory rate, and ventilatory equivalent for O2 (minute ventilation[▪e]/▪o2) were higher in the IC group compared with the control group. At AT, the systolic BP, O2 pulse, Vt, exercise duration, ▪o2, CO2 production (▪co2), and ▪e were lower, while the ▪e/▪o2 and ventilatory equivalent for CO2 (▪e/▪co2) were higher in the IC group (p < 0.05). At peak exercise, the IC group had a significantly lower systolic BP, O2 pulse, ▪e, Vt, exercise duration, ▪o2, and ▪co2, but higher ▪e/▪o2 and ▪e/▪co2 than the control group (p < 0.05). The ▪e/▪co2 slope was significantly higher for the IC group. No correlation existed between variables evaluated at rest vs during exercise. ConclusionsGas exchange analysis performed during exercise successfully differentiated children with heart failure from healthy children.