ABSTRACT
Objective To observe the response of left ventricular (LV)function and structure to chronic intermittent hypoxia (CIH)early stage in New Zealand white rabbits by echocardiography.Methods The New Zealand white rabbits were placed in the CIH chamber and exposed to hypoxia for 8 weeks (6 hours/day,6 days/week).The flow of nitrogen and oxygen were regulated into the customized chambers by the gas control delivery system.The fraction of inspired oxygen was changed from 21 % to 8% for 25 s of every 1 70 s.LV structure and function was assessed by echocardiography at CIH 0,1 ,2,4,6,8 weeks and histopathology was done by HE staining simultaneously.Results ①LV structural variables:compared with 0 week,LV posterior wall and interventricular septum thickness thickened at 6 week.LV end diastolic increased at 8 week (P 1 .Isovolumic relaxation time (IVRT)decreased at 1 week and 2 week,but increased at 8 week (P < 0.05 ).④ The myocardial pathology showed that myocardial fibers disordered slightly,cardiomyocytes swelled,nuclei increased and intracellular edema when exposed to CIH for 2 week and 4 week.Vacuolar degeneration,edema and congestion were found in intercellular substance at 6 week and 8 week.Conclusions ① LV systolic and diastolic function compensation started at CIH early stage then LV structure abnormality advent later.②IVCT and IVRT are sensitive indicators of LV systolic and diastolic function compensation.