[II-OR27-05] 心不全のないフォンタン患者（TCPC)での運動時換気亢進：残存チアノーゼの関与
キーワード：フォンタン, 換気応答, チアノーゼ
【Background】 Fontan patients are known to have augmented exercise ventilation. However, it is unsettled whether it is due to increased pulmonary dead space or augmented ventrilatory drive.【Methods】 Twenty-six Fontan patients, aged 8.5 ± 3.0 years, underwent symptom-limited treadmill cardiopulmonary exercise testing. Two groups of age- and sex- matched subjects served as controls: the biventricularly repaired (Bi, n=18), and the true control (C. n=29) groups. 【Results】 Peak oxygen uptake (VO2peak) was not different among groups (41.0 ± 8.4, 43.5 ± 6.6, and 45.9 ± 11.6 ml/min/kg for Fontan, Bi., and C groups, respectively, p=0.16). Fontan subjects, however, showed steeper alveolar ventilation/carbon-dioxide (VA/VCO2) regression slope (26.9 ± 3.4, 21.0 ± 2.0, and 21.6 ± 2.1, for Fontan, Bi, and C groups, respectively, p＜0.001), as well as lower end-expiratory carbon-dioxide fraction (FetCO2VAT) at ventilatory threshold (VAT) (4.4 ± 0.5, 5.5 ± 0.5, and 5.5 ± 0.4%, for the Fontan, Bi, and C groups, respectively, p＜0.001). The dead-space ventilation fraction at VAT was not different among the groups (0.33 ± 0.06, 0.33 ± 0.04, 0.35 ± 0.05 for the Fontan, Bi, and C groups, respectively, p = 0.54). Also in the Fontan subjects, arterial oxygen saturation at rest (SaO2rest) was correlated with VA/VCO2 regression slope (r = -0.41, p =0.04) and with FetCO2VAT (r = -0.53, p＜0.01).【Conclusions】 Fontan patients are characterized by exercise hyperventilation due to augmented ventilator drive, which is further augmented by residual hypoxemia.