The Study Of Relationships Between OSAHS And Left Ventricular Systolic Dysfunction

Objective To explore the mechanism that OSAHS damage leftventricular systolic function and observe effects of CPAP in OSAHS patients with leftventricular systolic dysfunction. Method Ninety-eight patients were assigned tothree groups: OSAHS with left ventricular systolic dysfunction(21 cases), OSAHSwithout left ventricular systolic dysfunction(47 cases) and control group(30 cases) byovernight polysomnography, echocardiography and gated radionuclide angiography.On the following morning, their plasma endothelin and blood pressure weremeasured. The twenty-one OSAHS patients with left ventricular systolic dysfunctionwere then randomly assigned to receive pharmacologic therapy either alone (10 patients)or with the addition of continuous positive airway pressure (11 patients) for threemonth. The assessment protocol was then repeated. Results (1)The SpO2Low inOSAHS with left ventricular systolic dysfunction is significantly lower than other twogroups (P<0.05). Mean apnea duration, %TST-SpO2<90% and %TST-SpO2<80% weresignificantly higher than other two groups (P<0.05). AHI and LAT were no significantdiff. compare with OSAHS without left ventricular systolic dysfunction.(2) TheSpO2Low in OSAHS without left ventricular systolic dysfunction is significantlylower than control group (P<0.05). Mean apnea duration, %TST-SpO2<90% and%TST-SpO2<80% were significantly higher than control group (P<0.05).(3) The plasmaendothelin among three groups have significantly difference(P<0.01), OSAHS withleft ventricular systolic dysfunction is highest, control group is lowest.(4) correlationanalysis: the plasma endothelin of OSAHS patients in two groups were all positivelyrelated to %TST-SpO2<90% (r=0.457 P=0.021; r=0.415 P=0.026),TST-SpO2<80%(r=0.372 p=0.016;r=0.334 P=0.031),LVEF in OSAHS with left ventricular systolicdysfunction was negatively related to TST-SpO2<80% (r=-0.529 P=0.024)and plasmaendothelin(r=-0.485 P=0.041).(5)After three months CPAP therapy in OSAHS withleft ventricular systolic dysfunction, the SpO2Low ,Mean apnea duration ,%TST-SpO2<90% and %TST-SpO2<80% were significantly improved (P<0.01), nocturnalmean heart rate and daytime mean systolic blood pressure were significantly decrease,the left ventricular ejection fraction had a significant absolute increase(P<0.01)followed with left ventricular end-systolic dimension and plasma endothelindecrease(P<0.05). Conclusion (1)OSAHS patients with left ventricular systolicdysfunction have more serious hypoxemia and duration was longer too, mean apneaduration longer equally.(2) the plasma endothelin were positively related tohypoxemia duration, the OSAHS patients with left ventricular systolic dysfunctionhave higher plasma endothelin content.(3)Recurrent sever hypoxemia and elevatedplasma endothelin may be one of the essential mechanism that OSAHS result in leftventricular systolic dysfunction.(4) CPAP may abolish sleep apnea and hypopnea,correct the recurrent hypoxemia , obviously reduce the plasma endothelin content,reduce the nocturnal mean heart rate and reduce systolic blood pressure, obviouslyimprove left ventricular systolic function.