RESUMO
BACKGROUND: Hypercholesterolaemia may alter cardiovascular autonomic function. We investigated the autonomic cardiovascular regulation during normoxia and hypoxia in familial isolated HC patients with or without statin treatment. MATERIALS AND METHODS: Low (LF-RR) and high (HF-RR) components of spectral analysis of RR interval and systolic arterial pressure (LF-SAP) were obtained during 5 min of normoxia and isocapnic hypoxia (10% O(2) ) in 10 normotensive familial HC patients without medication, in seven HC patients after a 12-week treatment period with 40 mg of simvastatin (HC + SVT) and in eight matched normal volunteers (CO). RESULTS: The HC patients had significant impairment of cardiac autonomic modulation parameters compared with CO at normoxia, which was maintained or even accentuated during hypoxia; these parameters included lower total variance of RR, increased normalized LF-RR, decreased normalized HF-RR, increased LF-RR/HF-RR ratio, higher LF-SAP component and reduced α index. However, the HC + SVT group had a significant improvement in all parameters: the LF-RR and LF-SAP decreased (indicating a decrease in cardiac and vascular sympathetic activity), the HF-RR increased (indicating an increase in parasympathetic activity) and the spontaneous baroreflex sensitivity improved. These changes were detected at normoxia and were maintained during hypoxia. CONCLUSIONS: Our data are the first to show that isolated HC is characterized by an increase in cardiac and vasomotor sympathetic drive, a decrease in cardiac vagal modulation and baroreflex impairment during normoxia and hypoxia. In addition, our data suggest that statin treatment has a potential role in restoring the physiological cardiovascular autonomic control at baseline and during cardiovascular challenge.
