Single ventricle function and exercise tolerance in adult patients after Fontan operation

Abstract

Background Patients who have undergone a Fontan operation (FO) may suff er from both systolic and diastolic single ventricle (SV) dysfunction.

Aim The aim of the study was to quantify non-invasively the systolic and diastolic single ventricle function in adult FO patients and to assess its eff ect on exercise tolerance.

Methods We investigated 21 patients (12F; 9M) after FO with morphological left ventricle with a mean age of 26 ± 6 years, and 17 age-matched, healthy people (control group). Pulse-wave Doppler signals from the mitral infl ow, aortic fl ow and tissue Doppler imaging of the mitral annulus were obtained. A cardiopulmonary exercise test (CPET) was performed.

Results The Fontan patients, as compared to the controls, had a lower value of SV ejection fraction (SVEF), E velocity, E/A ratio, aortic valve velocity time integral, exercise time, SatO₂, VO_2peak and signifi cantly higher E/E’ ratio, VE/VCO_2peak and VE/VO_2peak.

We found negative correlations between E/E’ and exercise time and VO2peak. Positive correlations were found between E/E’ and VE/VCO_2peak and age at surgery. S’ velocity correlated positively with SVEF, VO_2peak and negatively with E/E’ ratio.

Patients after FO with E/E’ ratio ≥ 12 had a signifi cantly lower oxygen uptake when compared to those with E/E’ ratio < 12.

Conclusion Adult patients after Fontan operations are characterized by both systolic and diastolic dysfunction of the single ventricle, associated with severe exercise intolerance refl ected by shorter duration of exercise with decreased oxygen uptake and increased ventilatory response. E/E’ ratio assessed by Tissue Doppler echocardiography can be a powerful predictor of oxygen uptake and ventilatory response.

Key Words:

• Adult
• Fontan
• exercise
• systolic
• diastolic function