Assessment of Symptoms and Exercise Capacity in Cyanotic Patients With Congenital Heart Disease
Approximately 1.0% of all children are affected by congenital heart defects. In 1994, it was estimated that > 500,000 patients with significant functional cardiac malformations reach adulthood in the United States. Supplementing echocardiography and cardiac catheterization data with cardiopulmonary exercise testing (CPX) offers an objective method to further characterize the limitations of the cardiovascular system in these patients. fully
Shunting of systemic venous blood into the arterial circulation through a central cardiac shunt alters ventilation due to an additional carbon dioxide load and hypoxemia, leading to impaired oxygen uptake (V02) at anaerobic threshold (AT) [Vo2AT] and under maximal exercise. Ventilatory efficiency— defined as the ratio of minute ventilation (Ve) vs carbon dioxide output (VC02) [at rest, Ve/VCO2 ratio; under exercise, VE vs VC02 slope]—has recently been used to quantify ventilation/perfusion mismatch, and to describe the pathophysiology of dyspnea in patients affected by chronic heart fail-ure. The impairment of ventilatory efficiency has been proven to significantly contribute to hyperpnea and dyspnea. Elevated values for the VE/VC02 ratio under exercise have been described in cyanotic patients with congenital heart defects. However, at present no studies have correlated these abnormalities in ventilatory efficiency with symptomatology and functional capacity in this patient population. This study attempts to further characterize functional limitation in adults affected by congenital cyanotic heart disease.
Materials and Methods
Twenty-five consecutive cyanotic patients with uncorrected congenital heart disease (12 women and 13 men) aged 18 to 59 years (mean age, 31 years; mean weight, 59 ± 12 kg; mean height, 171 ± 10 cm) underwent CPX. The study group consisted of patients treated in the outpatient clinic for congenital heart disease at the University Hospital Charite.