E-23 Free Communication/Poster - Cardiac: JUNE 3, 2011 7:30 AM - 12:30 PM: ROOM: Hall B
PURPOSE: The aim of this study was to examine changes in hemodynamic variables during 24h cycle ergometer exercise.
METHODS: Seven male subjects (38 yrs, 180 cm) were monitored throughout 24h at a constant workload of 20 watt below their first lactate turn point (LTP1) at 174±10 W. Body mass (BM), heart rate (HR), oxygen consumption (VO2), systolic blood pressure (SBP), cardiac output (CO) and stroke volume (SV) using a non-invasive device (Innocor) and 2-D echocardiograms [M-mode measurement - left atrial (LAD), ventricular end-diastolic (EDD), end-systolic (ESD) diameters and shortening fraction (SF)] were obtained over the left parasternal area and venous blood samples were collected and analyzed for N-terminal pro-brain natriuretic peptide (NT-proBNP) and hematocrit (HCT) at the end of 1, 6 and 24 hours of cycle exercise.
RESULTS: BM (78.4±2.3, 78.0±2.2, 78.7±2.2 kg), HR (128±4, 140±3, 124±3 min-1),VO2 (34.5±1.6, 34.7±1.6, 35.1±1.5 ml·min-1·kg-1), SBP (162±7, 165±8, 161±7 mmHg), CO (17,4±0.5, 17.3±0.6, 17.6±0.7 l·min-1), SV (137±5, 123±5, 142±7 ml), LAD (36±2, 36±2, 41±2 mm), EDD (51±2, 49±1, 54±1 mm), ESD (30±2, 31±1, 31±1 mm), SF (40±3, 35±3, 42±3 %), NT-proBNP (30±5, 97±26, 569±146 pg·ml-1), and HCT (43.3±0.7, 44.4±0.5, 41.4±0.6 %). Significant correlations (p<0.05) were found between delta 6/24 values for HR and SV (r=-0.907), LAD (r = -0.814), SF (r = -0.853), BM and LAD (r = 0.814), SF (r = 0.784), and SV LAD (r = 0.777), SF (r =0.854).
CONCLUSIONS:Our study suggests that the decrease in HR during the 24 h aerobic exercise was due to hypervolemia and the associated ventricular workload that resulted in increases in SV and NT-proBNP as a consequence of increases in left ventricular diastolic dimension.