Tanabe Y, Takahashi M, Hosaka Y, Ito M, Ito E, Suzuki K
Department of Internal Medicine, Niigata Prefectural Shibata Hospital, Shibata City, Japan.
J Am Coll Cardiol. 2000 Apr;35(5):1228-36. doi: 10.1016/s0735-1097(00)00517-9.
The aim of this study was to characterize the kinetics of cardiac output during recovery from maximal exercise in patients with chronic heart failure (CHF).
Recent studies have shown that oxygen uptake kinetics during recovery from exercise are delayed in patients with CHF. However, the kinetics of cardiac output during recovery from maximal exercise in CHF has not been examined.
Thirty patients with CHF performed maximal upright ergometer exercise with respiratory gas analysis. Kinetics of oxygen uptake (VO2) and carbon dioxide output (VCO2) during recovery were characterized by T1/2, the time to reach 50% of the peak values. Cardiac output was measured at 1-min intervals during exercise and recovery. Kinetics of cardiac output during recovery were characterized by the ratios of cardiac output during the first 4 min of recovery to cardiac output at peak exercise. Overshoot of cardiac output was defined as a further increase in cardiac output at 1 min of recovery above the cardiac output at peak exercise.
Both T1/2 VO2 and T1/2 VCO2 increased as CHF worsened. The ratios of cardiac output during recovery to cardiac output at peak exercise were significantly correlated with T1/2 VO2 (r = 0.47 to 0.62, p < 0.05) and T1/2 VCO2 (r = 0.40 to 0.70, p < 0.05). There was a negative correlation between cardiac index at peak exercise and both T1/2 VO2 (r = -0.65, p < 0.001) and T1/2 VCO2 (r = -0.60, p < 0.001). Overshoot of cardiac output was recognized in 11 of 30 patients. Cardiac index at peak exercise was significantly lower in patients with overshoot (4.5 +/- 0.9 L/min/m2) than in those without overshoot (6.1 +/- 2.1 L/min/m2, p < 0.05). However, because of a continued increase in cardiac output at 1 min of recovery in patients with overshoot, there were no differences in cardiac index after the first minute of recovery. Heart rate at peak exercise and recovery of heart rate did not differ between these groups. Overshoot of cardiac output was caused by a rebound increase in stroke volume which was due to a reduction in systemic vascular resistance.
Prolonged kinetics of VO2 or VCO2 during recovery from maximal exercise represent impairment of circulatory response to exercise and delayed recovery of cardiac output after exercise. Overshoot of cardiac output at 1 min of recovery was characteristic of severe CHF with poor cardiac output response to exercise.
本研究旨在描述慢性心力衰竭（CHF）患者从最大运动恢复过程中心输出量的动力学特征。
最近的研究表明，CHF患者运动恢复过程中的摄氧动力学延迟。然而，CHF患者从最大运动恢复过程中心输出量的动力学尚未得到研究。
30例CHF患者进行最大直立测力计运动并进行呼吸气体分析。恢复过程中摄氧量（VO2）和二氧化碳排出量（VCO2）的动力学以T1/2（达到峰值50%的时间）来表征。在运动和恢复过程中每隔1分钟测量一次心输出量。恢复过程中心输出量的动力学以恢复前4分钟的心输出量与运动峰值时的心输出量之比来表征。心输出量的过冲定义为恢复1分钟时的心输出量比运动峰值时的心输出量进一步增加。
随着CHF病情加重，T1/2 VO2和T1/2 VCO2均增加。恢复过程中心输出量与运动峰值时的心输出量之比与T1/2 VO2（r = 0.47至0.62，p < 0.05）和T1/2 VCO2（r = 0.40至0.70，p < 0.05）显著相关。运动峰值时的心指数与T1/2 VO2（r = -0.65，p < 0.001）和T1/2 VCO2（r = -0.60，p < 0.001）均呈负相关。30例患者中有11例出现心输出量过冲。出现过冲的患者运动峰值时的心指数（4.5 +/- 0.9 L/min/m2）显著低于未出现过冲的患者（6.1 +/- 2.1 L/min/m2，p < 0.05）。然而，由于出现过冲的患者在恢复1分钟时心输出量持续增加，恢复第一分钟后心指数没有差异。这些组之间运动峰值时的心率和心率恢复情况没有差异。心输出量过冲是由每搏输出量的反弹增加引起的，这是由于全身血管阻力降低所致。
最大运动恢复过程中VO2或VCO2的动力学延长代表运动循环反应受损和运动后心输出量恢复延迟。恢复1分钟时的心输出量过冲是严重CHF的特征，其运动心输出量反应较差。
