[A preliminary study on the early diagnosis of sinus dysfunction in patients with obstructive sleep apnea syndrome].

Objectives: To observe the characteristics of sinus dysfunction (SD) in patients with obstructive sleep apnea syndrome (OSAHS) and to explore the method for early detection of SD in these patients.

Methods: From January 2007 to June 2008, 119 snorers were recruited. All of them underwent polysomnography (PSG) examination and received atropine test under ultramicroelectrocardiogram (UMECG). Based on the results of atropine test, they were divided into 2 groups: the UMECG group (n = 78) including subjects diagnosed as having SD by a positive result of atropine test with UMECG, and the non-UMECG group (n = 41) including subjects with a negative result of atropine test. Comparison was made for the incidence of OSAHS between the 2 groups and the diagnostic sensitivities for SD between UMECG and PSG electrocardiogram (SD(PSG)). The association was also observed between PSG parameters and SD(PSG).

Results: The incidence of OSAHS in the non-UMECG group was significantly higher than that in the UMECG group (31% vs 55%, P < 0.05). SD(PSG) was not detected in the non-UMECG group. In the UMECG group, SD(PSG)/UMECG was 26/43 (60%) in the OSAHS subjects and 29/35 (83%) in the non-OSAHS subjects (P < 0.05). Of the OSAHS subjects in the UMECG group, SD(PSG)/UMECG was 10/20 (50%) in the mild to moderate OSAHS subjects and 16/23 (70%) in the severe OSAHS subjects (P < 0.05). Compared with the OSAHS subjects with UMECG but without SD(PSG), the average duration of apnea events as well as the longest apnea event were prolonged while the minimal SaO2 was lower in those OSAHS patients with SD(PSG). Among all of the 17 OSAHS subjects with SD(UMECG) but with out SD(PSG), there were 13 subjects (76%) with a fastest sinus heart rate slower than 90 beats/min even though they also had hypoxemia during sleep.

Conclusions: SD was associated with OSAHS. The actual incidence of SD may be underestimated by PSG only, especially in those with mild to moderate OSAHS. SD should be suspected in OSAHS patients whose fastest sinus rate is lower than 90 beats/min in spite of hypoxemia. UMECG was more sensitive for early detection of SD.