Abstract
Background: Obstructive sleep apnea has detrimental effects on function of left ventricle. It is also known that large decreases in intrathoracic pressure occur during obstructive apnoeas.
The aim of this study was to determine the acute changes in left sided heart function that occur in response to the decreased intrathoracic pressure in an obstructive sleep apnea model in rats under condition of normoxia.
Methods: Experiments were conducted in ten male adult Wistar rats weighing 350 gr, which were anaesthetized with Ketamine-Xylazine intraperitoneally. Animals were breathing after being tracheostomized and connected in a circuit with an electromagnetic valve which was closing periodically mimicking obstructive apnoeas.Arterial saturation was at SaO2:97% constantly. End Diastole Volume (EDV), Stroke Volume (SV) and Ejection Fraction (EF%) of left ventricle were measured with an anatomical M-mode echocardiographic method. Data analyzed and compared between quite breathing (time 0) and breathing after two hours of airway obstructions (time 0+2).
Results: The cardiac measurements were compared using the Wilcoxon signed-rank test. EDV and SV were statistically significant reduced (p<0.05) between time 0 and time 0+2. EF was reduced but not statistically significant at the same time period.
Conclusions: In this study our findings suggest that left ventricular function is affected acutely with reduction of EDV and SV after two hours of airway obstructions independently of hypoxaemia. These results suggest that in obstructive sleep apnea, negative intrathoracic pressure which occurs during apnea may contribute to changes in myocardial mechanics.
- © 2011 ERS
