[Sleep-related respiratory disorders and coronary heart disease]

A review of the literature shows that more than 50% of examined patients suffering from coronary heart disease were also suffering from sleep-related apnea. We were able to diagnose a pathological sleep apnea in 9 out of 25 patients (36%) suffering from an angiographically confirmed coronary 2-vessel and 3-vessel disorder. Patients with this combination--this is the hypothesis derived from our study--are at risk due to nocturnal apnea-induced myocardial ischaemia and rhythmic disorders. In 15 patients with sleep apnea and coronary heart disease or small vessel disease, nocturnal polysomnography was conducted, in parallel a 6-channel ECG was recorded. The apnea index (second night) was on the average 33 phases/h, the maximal duration of an apnea phases being 120 seconds. The minimal blood gas saturation recorded during sleep was between 46 and 89% (median 76.0%). In 4 of the 15 patients it was possible to confirm myocardial ischaemia (correlated via REM and also via NREM) with a maximum duration of 60 seconds, mainly during the phases of maximal apnea activity and blood gas desaturation. On comparing the ventricular arrhythmias waking/sleep, the Lown class did not change in 12 patients; there was deterioration in 2 patients and in one patient a qualitative improvement during the sleep phase. Patients suffering from sleep-related respiratory disorders and coronary heart disease are at cardiac risk, the more so since long-lasting apneas can lead to conditions of hypoxia at the heart in pre-existing changes in the coronary arteries, restricted coronary reserves and reduced tolerance to hypoxia. Such hypoxia can in turn induce enhanced electrical instability and a disturbance of the contractile function.