Relationship Between OSAHS-Mediated Intermittent Hypoxemia And Left Ventricular Hypertrophy

Background and Objective:Obstructive sleep apnea-hypopnea syndrome（OSAHS）characterized by repetitive episodes of partial or complete collapse of the upper airway during sleep.These periods of obstructed breathing result in intermittent hypoxaemia（IH）.OSAHS has the characteristics of high prevalence,low detection rate,low treatment rate,and great harm.The pathophysiological mechanisms of OSAHS include changes in intrathoracic pressure,microarousals,reduction of rapid eyes movement sleep duration,repeated episodes of hypoxia etc.So far,the view of most researchers think IH is the main influence factor of all.OSAHS is closely associated with cardiovascular diseases such as hypertension,pulmonary hypertension,endothelial dysfunction and arrhythmia,but the relationship between OSAHS-mediated IH and left ventricular hypertrophy is not clear.Therefore,the purpose of this study was to investigate whether OSAHS-mediated IH is associated with left ventricular hypertrophy,and further evaluate the advantages and disadvantages of IH parameters in predicting left ventricular hypertrophy and diastolic function.Subjects and Methods:We consecutively enrolled 286 patients undergoing concurrent polysomno-graphy（PSG）in the cardiovascular department of the Second Affiliated Hospital of Nanchang University from September 2015 to November 2017.Patient’s medical history,drinking history,smoking history was acquired.After that,plasma biochemical tests were done in order to obtain the values of creatinine,uric acid,urea,total cholesterol,triglycerides,high-density lipoprotein cholesterol,low-density lipoprotein cholesterol,fasting Serum glucose,and homocysteine.All patients underwent PSG and echocardiography.We divided patients into non-OSAHS group,mild OSAHS group,moderate OSAHS group and severe OSAHS group according to apnea hypopnea index（AHI）.Left ventricular mass index related to Height^2.7(LVMI-height^2.7)was calculated by echocardiography measurements.All data was analyzed using SPSS Statistics 22.0.The statistical methods we used include:one-way ANOVA,Mann-Whiney U test,Kruskal Wallis H test and univariate and multivariate linear regression analysis.The p<0.05 was considered statistically significant.Results:286 eligible patients were enrolled in this study,including 16（5.6%）in the non-OSAHS group,38（13.3%）in the mild OSAHS group,31.1%（moderate OSAHS）,and 143（50%）in the severe OSAHS group.○1 Compared with the non-OSAHS group,the ages of the mild to moderate OSAHS group were significantly higher（P<0.05）.Compared with non-OSAHS group,body mass index（BMI）in severe OSAHS group was significantly higher,with a statistically significant difference（P<0.001）.And 55.9%of patients with severe OSAHS achieved BMI levels of obesity（BMI≥28）.○2 There was no significant difference in systolic blood pressure（SBP）between all groups,but there was a significant difference in diastole blood pressure（DBP）between the severe OSAHS group and the non-OSAHS group（P<0.05）.The proportion of patients with a history of hypertension in the moderate to severe OSAHS group was significantly higher than that in the non-OSAHS group（P<0.05）.Similarly,the prevalence of hypertension in the mild OSAHS group was lower in the moderate OSAHS group（P<0.05）.○3Comparing the differences of LVMI-height ^2.7 between all groups,it was found that the LVMI-height^2.7 was significantly higher in the moderate and severe OSAHS group than in the non-OSAHS group（P<0.05）.○4 Compared with non-OSAHS group,the mean nocturnal oxygen saturation（MSpO₂）and lowest oxygen saturation（LSpO₂）in the moderate and severe OSAHS group were lower（P<0.05）,and the oxygen desaturation index（ODI）and TS90%higher（P<0.05）.○5 We explored the relevant factors affecting the LVMI-height^2.7.Univariate linear regression analysis show that gender,BMI,SBP,DBP,history of hypertension,urea,creatinine,uric acid,estimated glomerular filtration rate（eGFR）,AHI were correlated with LVMI-height^2.7 respectively.There was a significant negative correlation between LVMI-height^2.7 and MSpO₂ and LSpO₂（P<0.001）,however,a significant positive correlation between LVMI-height^2.7 and ODI and TS90%was observed（P<0.001）.○6 Multivariate linear regression analysis show that LVMI-height^2.7 was associated with gender,BMI,SBP,urea,creatinine,ODI,and the correlation was independent of other influencing factors,AHI,and other IH related indicators.○7According to Ganau criteria,all cases were divided into four groups:normal geometry,concentric remodeling,eccentric hypertrophy,concentric hypertrophy.It was found that there was a difference of ODI between normal geometry and concentric hypertrophy（P<0.05）,and there was no significant difference between the other groups（P>0.05）.Conclusion:The severity of OSAHS is associated with left ventricular hypertrophy,and OSAHS-mediated IH is the main cause of left ventricular hypertrophy.ODI can be used as an independent predictor of IH-induced or aggravated left ventricular hypertrophy,and ODI is associated with left ventricular concentric hypertrophy.