Passive Leg Raising Correlates with Future Exercise Capacity after Coronary Revascularization

Cardiovascular Autonomic Response to Orthostatic Stress Under Hypoxia in Patients with Spinal Cord Injury

Huang, Shu-Chun, Kuo-Cheng Liu, Alice M.K. Wong, Shih-Chieh Chang, and Jong-Shyan Wang. Cardiovascular autonomic response to orthostatic stress under hypoxia in patients with spinal cord injury. High Alt Med Biol. 19:201-207, 2018.

AIMS

Determining whether systemic hypoxia aggravates the severity of autonomic cardiovascular dysfunction in orthostatic stress among patients with spinal cord injuries (SCIs).

METHODS

Twenty-four male patients with chronic SCI whose neurological levels were above T6 were recruited. Twenty-five healthy men were enrolled in the control group. Five-minute supine rest (SR) and head-up tilt (HUT) at 60° were performed in normoxia and after 1 hour, 13.5% fraction of inspired O₂ exposure. A noninvasive cardiac output (CO) monitor was used to measure stroke volume (SV), CO, total peripheral resistance (TPR), and blood pressure (BP), whereas heart rate variability (HRV) was performed to determine cardiac autonomic activity. Digital volume pulse analysis was applied to measure arteriolar tone.

RESULTS

In normoxia from SR to HUT, systolic and diastolic BPs declined, SV decreased, and heart rate increased, whereas CO and TPR showed a declining trend in the SCI group. Sympathetic activation and vagal withdrawal were also disclosed in the HRV analysis. In hypoxia, the change of these cardiovascular responses from SR to HUT exhibited no difference to normoxia in the SCI group. No significant difference in arterial desaturation was observed between the two groups (82.9% vs. 80.4%).

CONCLUSIONS

Cardiovascular adaptation to orthostatic stress is not affected by subacute steady-state hypoxia in chronic SCI patients with neurological levels higher than T6.

Short-term intensive training attenuates the exercise-induced interaction of mono-1/2 cells and platelets after coronary bypass in cardiac patients

The interaction between platelets and monocytes plays a critical role in the pathogenesis and progression of cardiovascular diseases. This study investigated how short-term intensive training (SIT) influences monocyte subset characteristics and exercise-induced monocyte and platelet aggregates (MPAs) following elective coronary bypass (CABG) in cardiac patients. Forty-nine patients hospitalised for CABG were randomised into SIT (N=26) and conventional training (CT, N=23) groups. The SIT subjects underwent supervised aerobic training at 80~120 % of the ventilatory anaerobic threshold based on sub-maximal exercise tests performed 7 days post-CABG for 20 sessions with two sessions/day and 30 min/session, which were completed within four weeks after surgery. The CT subjects performed light-intensity conditioning exercise for ≤4 sessions. Resting and maximal exercise-mediated monocyte characteristics and MPA were determined before and following intervention. The SIT group had a larger improvement in ventilation efficiency and anaerobic threshold than the CT group; the SIT group exhibited larger reductions in blood monocyte subtypes 1 and 2 (Mono1 and 2) counts at rest than the CT group; the SIT group but not the CT group exhibited attenuated formation of Mono1/platelet hetero-aggregation (MPA1) and CD42b expression on Mono1/2 caused by strenuous exercise; and plasma levels of macrophage inflammatory protein-1β and soluble P-selectin showed similar trends as Mono1/2 and MPA1, respectively. In conclusion, SIT modestly improved aerobic capacity in patients following CABG. Moreover, SIT simultaneously ameliorated the CD42b expression of Mono1/2 cells and maximal exercise-induced MPA1, which may reduce the risk of inflammatory thrombosis.