Patent foramen ovale: a novel cardiovascular risk factor in patients with sleep disordered breathing and high altitude dwellers?

Abstract

Diseases associated with chronic hypoxaemia are a leading cause of morbidity and mortality in Western countries. Epidemiological data indicate that cardiovascular diseases contribute substantially to this problem, but the underlying mechanisms are incompletely understood. Sleep disordered breathing and high altitude exposure are frequent conditions associated with hypoxaemia. Recent evidence suggests that in these conditions the concomitant presence of a patent foramen ovale plays an important pathogenic role. For example, in patients with obstructive sleep apnoea the presence of a patent foramen ovale is associated with more severe sleep disordered breathing, nocturnal oxygen desaturation, generalised endothelial dysfunction and arterial hypertension. After patent foramen ovale closure, both sleep disordered breathing and cardiovascular phenotype improve, suggesting the existence of a possible causal link. During short-term high altitude exposure, the presence of a patent foramen ovale, by aggravating altitude-induced hypoxaemia, facilitates exaggerated pulmonary hypertension. Interestingly, there is increasing evidence showing that in high-altitude dwellers a patent foramen ovale also alters the cardiovascular phenotype. In this article we will summarise recent evidence demonstrating how a patent foramen ovale alters the cardiovascular phenotype and increases cardiovascular risk in patients with sleep disordered breathing and high-altitude dwellers.

Sleep apnoea and pulmonary hypertension in high-altitude dwellers: more than an association?

“…While sleep disturbances in lowlanders arriving at high altitude were traditionally seen as a sign of poor acclimatisation, recent observations indicate that in lowlanders acutely exposed to high altitude, sleep-disordered breathing may protect against acute mountain sickness (AMS), as evidenced by more severe central apnoea/hypopnea in lowlanders resistant to AMS than in those who are susceptible to this problem [21]. Similarly, the role of sleep-disordered breathing in the pathogenesis of chronic mountain sickness and the development of cardiovascular dysfunctions in highlanders needs to be further elucidated [22]. Last, but not least, the problem of treatment for pulmonary hypertension and sleep apnoea in these high altitude populations often living in remote areas needs to be addressed, considering both pharmacological interventions (e.g.…”