Mechanisms underlying abnormal cardiorespiratory response in Fontan patients - 05/01/18
Résumé |
Background |
Low peak oxygen consumption (peak VO2) is a strong predictor of mortality in adults with congenital heart diseases. In univentricular hearts, after Fontan procedure, peak VO2 is known low at 59% of predicted value for the 50th percentile. But the mechanisms underlying this abnormal cardiorespiratory response to exercise are not well known.
Objectives |
We aimed to determine which parameters can predict low peak VO2 (<59% of predicted value) in Fontan patients.
Methods |
Twenty-one patients (mean age 23±8 years) underwent cardiopulmonary exercise testing (CPX) with arterial blood gas measurements.
Results |
As expected, peak VO2 was low (24.4mL/kg/min). All patients, despite oxygen saturation, had resting shunt with PaO2+PaCO2 <120mmHg (mean 96±8mmHg). Twelve patients had peak VO2 <59% of predicted value, which is considered <50th percentile in Fontan population. In this group, resting oxygen saturation was lower (94.3±1.8% vs. 96.7±1.4%, P=0.02), alveolar–arterial gradient was higher at rest (52±9mmHg vs. 44±5mmHg, P=0.03) and at exercise (58±10mmHg vs. 50±6mmHg, P=0.04). Secondly, these patients had lower exercise heart rate (122±38bpm vs. 169±25bpm, P=0.002), lower chronotropic reserve (49±31bpm vs. 79±17bpm, P=0.009) and had more often pacemakers (3 patients versus 0, P=0.05). Finally, in this group with altered peak VO2, we found more Fontan procedures (or modified Fontan) than extracardiac total cavopulmonary connections (5 patients or 42% vs 1 or 11%, P=0.03), patients were older (27.6±7 years vs. 16.8±6.4 years, P=0.0009), and converted to extracardiac cavopulmonary connection later (at 21.1±13.9 years old vs. 3.8±2.4years old, P=0.002).
Conclusion |
Severe alteration of aerobic capacity evaluated by peak VO2 measurement in Fontan patients is correlated to the importance of cyanosis, the limited capacity to raise heart rate at exercise and the type of surgery.
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Vol 10 - N° 1
P. 138 - janvier 2018 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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