Risques liés au sommeil chez les patients cardiovasculaires

In those patients with compromised cardiovascular status during wakefulness, sleep may be a period at risk. The two main mechanisms involved in nocturnal cardiac events are the increased activity of the autonomous nervous system dependent on sleep stages and the depressed ventilatory control which may impact a vulnerable cardiac status. The main cardiovascular disorders, coronary ischaemia, cardiac arrhythmias, hypertension and heart failure, may worsen during sleep. Nocturnal ischaemia and angina mainly occur during REM sleep, specially Prinzmetal's angina which is remarkable for an increase of attacks during the second half of the night. After myocardial infarction, NREM sleep may trigger nocturnal angina pain and awakenings linked to hypotension responsible for a decreased perfusion of coronary vessels. In patients whose nocturnal heart rate remains elevated, beyond 90/min, threat to life is increased. In subjects with long QT syndrome, the cardiac pauses may induce arrhythmias and occur mainly during sleep. Atrial fibrillation is a very frequent arrythmia. It is associated with an increased morbidity and mortality. It is more often triggered during night-time than during daytime. Brugada syndrome and unexplained nocturnal death syndrome are two genetically identical conditions. They are usually fatal during sleep. Non-dippers (patients whose blood pressure does not diminish during the night) have an increased risk of cardiovascular and cerebrovascular complications. Thus it is important to detect nocturnal abnormalities of cardiovascular patients in order to prevent sleep associated risks.