ABSTRACT
Background: Congenital central hypoventilation syndrome (CCHS) is a life-threatening disorder of autonomic respiratory control. Mutations in the paired-like homeobox 2B (PHOX2B) gene impair respiratory drive, causing hypercarbia and hypoxaemia. Most patients with CCHS are diagnosed in the neonatal period; however, a few are diagnosed in adulthood. Case summary: We report a 32-year-old man with a history of unexplained cyanosis 14 days after birth. He presented to our hospital with breathlessness and abnormal electrocardiogram findings discovered in a health check-up. Pulmonary hypertension (PH) was suspected based on electrocardiographic and echocardiographic evidence of right ventricular (RV) overload. Results of pulmonary function tests and chest computed tomography were normal. Arterial blood gas analysis revealed type 2 respiratory failure without a significant alveolar-arterial oxygen gradient, indicating alveolar hypoventilation. Right heart catheterization (RHC) showed pre-capillary PH [pulmonary artery pressure 47/24 (35) mmHg], and a hyperventilation challenge test and a non-invasive positive pressure ventilation (NPPV) treatment during RHC provided drastic improvement in PH [pulmonary artery pressure 28/12 (18) mmHg]. Congenital central hypoventilation syndrome was diagnosed based on genetic testing (20/25 polyalanine repeat expansion mutations in PHOX2B). After NPPV therapy initiation, the RV overload was slightly improved. Discussion: Some patients with CCHS develop mild hypoventilation without overt clinical signs, and PH can be the first clinical manifestation. In our case, the hyperventilation challenge test improved PH. Although CCHS causes chronic alveolar hypoxia and hypoxic pulmonary vasoconstriction with subsequent PH, optimal ventilation therapy can improve pulmonary circulation even in affected adults.
ABSTRACT
AIMS: In vasospastic angina (VSA), coronary vasomotion abnormalities could develop not only in epicardial coronary arteries but also in coronary microvessels, where calcium channel blockers (CCBs) have limited efficacy. However, efficacy of exercise training for VSA remains to be elucidated. We thus aimed to examine whether vasodilator capacity of coronary microvessels is impaired in VSA patients, and if so, whether exercise exerts beneficial effects on the top of CCBs. METHODS: We performed 2 clinical protocols. In the protocol 1, we measured myocardial blood flow (MBF) using adenosine-stress dynamic computed tomography perfusion (CTP) in 38 consecutive VSA patients and 17 non-VSA controls. In the protocol 2, we conducted randomized controlled trial, where 20 VSA patients were randomly assigned to either 3-month exercise training group (Exercise group) or Non-Exercise group (n= 10 each). RESULTS: In the protocol 1, MBF on CTP was significantly decreased in the VSA group compared with the Non-VSA group (138 ± 6 vs 166 ± 10 ml/100 g/min, P = 0.02). In the protocol 2, exercise capacity was significantly increased in the Exercise group than in the Non-Exercise group (11.5 ± 0.5 to 15.4 ± 1.8 vs 12.6 ± 0.7 to 14.0 ± 0.8 ml/min/kg, P < 0.01). MBF was also significantly improved after 3 months only in the Exercise group (Exercise group, 145 ± 12 to 172 ± 8 ml/100 g/min, P < 0.04; Non-Exercise group, 143 ± 14 to 167 ± 8 ml/100 g/min, P = 0.11), although there were no significant between-group differences. CONCLUSIONS: These results provide the first evidence that, in VSA patients, exercise training on the top of CCBs treatment may be useful to improve physical performance, although its effect on MBF may be minimal.
