G. Lapierre

CEREBRAL OXYGENATION/PERFUSION, CARDIOPULMONARY AND HEMODYNAMIC RESPONSES DURING MAXIMAL INCREMENTAL EXERCISE IN HEART TRANSPLANT RECIPIENTS VS. HEALTHY CONTROL SUBJECTS

BACKGROUND: Accurate measurement of physical activity (PA) is necessary to monitor trends, assess relations with health and measure adherence to PA guidelines. While accelerometers provide accurate measures of PA they rely on validated cut-points to quantify time spent in light, moderate and vigorous intensities. Cut-points have largely been established using healthy populations; however, accelerometer output can differ based on cardiorespiratory fitness, suggesting that among individuals with compromised functioning such as those with coronary artery disease (CAD); these cut-points may lead to a misclassification of intensity. The objective of this study was to compare well-known and widely used cut-points (Sasaki) derived from healthy adults with those developed in a CAD population (Mark). METHODS: Two-hundred and thirty-one adults with CAD (mean SD: 63.7 9.2 years) wore an ActiGraph GT3X accelerometer for a minimum of 4 consecutive days and 10 hours/day. Daily time spent in moderate-to-vigorous PA (MVPA) was compared using two cut-point definitions: Mark (58.3 10.7 years, mean v

CEREBRAL OXYGENATION/PERFUSION, CARDIAC HEMODYNAMICS DURING EXERCISE AND COGNITIVE FUNCTIONS IN OBESE PATIENTS

(CO) and cerebral oxygenation/perfusion (COP) in heart transplant recipients (HTR) and age-matched controls (AMC) during maximal exercise (ME), 2) to study the relationships between VO2 peak, CO, COP inHTR and AMC. 27 AMC and 26HTR were recruited. VO2 peak and cardiac hemodynamic (impedance cardiography) were measured during a ME. COP (O2Hb, tHb) was measured using near-infrared spectroscopy (NIRS). RESULTS: Compared to AMC, HTR had a lower VO2 peak (ml/min/kg of lean body mass), maximal (max) cardiac index (CImax), max ventilation, max tidal volume and max respiratory frequency vs. AMC (P<0,0001). End-systolic volume index and systemic vascular resistance index were higher inHTR (P<0,05). At 50% and 75% of peak, O2Hb was lower in HTR (P<0,05). At 100% of peak, tHbwas lower inHTR (P<0,05). At recovery, O2Hb and tHb were lower in HTR (P<0,05). VO2 peak (ml/ min/kg) and CImax were correlated to DO2Hb (R1⁄40,33 and 0,36, P<0,05) and DtHb (R1⁄40,35 and 0,44, P<0,01). CONCLUSION: VO2 peak is reduced in HTR because of central, ventilator, peripheral factors and medication. Lower VO2 peak and CImax in HTR does not seem to really affect COP during exercise. During exercise, our results suggest a lower O2 saturation in HTR. In HTR, the lower tHb at ME could be due to a better physical capacity in AMC. In HTR, differences in COP during recovery could be explained by the absence of cardiac overshoot phenomenon, medication and/or endothelial dysfunction.