© 2008 American Thoracic Society
Arterial Stiffness and Chronic Obstructive Pulmonary DiseaseTo the Editor:In an article entitled "Arterial Stiffness and Osteoporosis in Chronic Obstructive Pulmonary Disease," Dr. Sabit and colleagues found an increased arterial stiffness in patients with chronic obstructive pulmonary disease (COPD) (1). The increased aortic pulse wave velocity (PWV) was related to airflow obstruction, systemic inflammation, and the presence of osteoporosis. This study is particularly interesting, and we would like to submit some points for consideration. In Sabit and colleagues' study, heart rate (HR) was significantly increased in the COPD patients compared with the controls. Previous studies, as reviewed by Davies and Struthers (2), have shown that arterial compliance indices, such as PWV and augmentation index, are affected by HR. In these studies, an inverse relationship was observed between HR and the augmentation index, whereas a positive correlation was observed between HR and PWV. Consequently, caution must be exercised in the interpretation of Sabit and coworkers' results (1). Nevertheless, the results of Sabit and coworkers' study are supported by recent work performed by our team. In this study (3), significant decreases in total arterial compliance and brachial artery compliance were found in COPD patients in comparison with healthy subjects. Moreover, and consistent with Sabit and coworkers' results, the magnitude of changes in the peripheral circulation was related to the severity of COPD. Interestingly, an accelerated HR was also observed in our patients with COPD. Sympathetic hyperactivity could explain this significant HR increase. Indeed, previous work has demonstrated sympathetic activation in patients with chronic respiratory failure (4). Hypoxia, systemic inflammation, and obstruction of the bronchi have been incriminated. Sympathetic vascular smooth muscle activation promotes impairment in arterial compliance (5) and could contribute to the arterial stiffness found in patients with COPD. Zureik and colleagues (6) found that impaired pulmonary function (restrictive or obstructive pulmonary disease) was associated with aortic stiffness in men. In that study, large artery compliance was measured by applanation tonometry to give a regional estimation of arterial compliance over the trunk (carotid to femoral). Aortic stiffness might have stemmed from an association between reduced lung function and atherosclerosis. Cigarette smoking, hypoxia, and systemic inflammation could be involved in the high incidence of atherosclerosis in COPD patients. In total, several factors, such as atherosclerosis, sympathetic hyperactivity, and systemic inflammation, could participate in the alterations of the peripheral circulation in COPD patients. To reduce the cardiovascular risk and consequently to improve the prognosis of patients with COPD, these different factors should be taken into account.
Université de la Méditerranée
Assistance Publique des Hôpitaux FOOTNOTES Conflict of Interest Statement: Neither author has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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