Obstructive sleep apnea syndrome: more insights on structural and functional cardiac alterations, and the effects of treatment with continuous positive airway pressure.
OBJECTIVE
We studied structural and functional cardiac alterations in obstructive sleep apnea (OSA), their relationship to the severity of OSA, and the effects of treatment with continuous positive airway pressure (CPAP).


BACKGROUND
Obstructive sleep apnea may influence the cardiac function by several mechanisms in the awake patient.


METHODS
Left and right ventricular morphology and function were studied using echocardiography before and after treatment with CPAP in symptomatic patients (Epworth sleepiness score, 10 +/- 4.8) with severe OSA (apnea-hypopnea index [AHI], 42 +/- 24). The patients (n = 43, 32 men) had no known cardiac disease and were obese (body mass index, 31.6 +/- 5.4 kg/m2). The same echocardiographic parameters were studied in age-matched overweight patients (n = 40; body mass index, 26.4 +/- 2.3 kg/m2).


RESULTS
The patients were hypertensive (systolic blood pressure, 153 +/- 25 mm Hg), with a higher resting heart rate (77 +/- 10 beats/min, p = 0.008) compared with age-matched control patients (n = 40). There was right ventricular dilatation, hypertrophic interventricular septum, reduced left ventricular stroke volume, tissue Doppler-determined systolic and diastolic velocities of the left and right ventricle, and normal pulmonary artery pressure. The structural and functional parameters were significantly associated with AHI (p < 0.004). Multiple stepwise regression showed the interventricular septum thickness, right ventricular free wall, and mitral annulus tissue Doppler systolic velocities to be predictive of a higher AHI (p < 0.001). Six months after treatment with CPAP, significant improvements were observed in the symptoms and hemodynamics, as well as left and right ventricular morphology and function.


CONCLUSIONS
The structural and functional consequences of OSA on the heart are influenced by the severity of AHI. These effects are reversible if the apneic episodes are abolished.
Department of Cardiology and Pulmonary Medicine, University Hospital Antwerp, Antwerp, Belgium. bharati.shivalkar@skynet.be
Bharati
B
Shivalkar
Caroline
C
Van de Heyning
Mieke
M
Kerremans
Diana
D
Rinkevich
Johan
J
Verbraecken
Wilfried
W
De Backer
Christiaan
C
Vrints
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D045422:Continuous Positive Airway Pressure; D004452:Echocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000628:therapy; D016896:Treatment Outcome