Leung D Y, Griffin B P, Snader C E, Luthern L, Thomas J D, Marwick T H
Department of Cardiology, The Cleveland Clinic Foundation, Ohio 44195, USA.
Am J Cardiol. 1997 Apr 1;79(7):914-20. doi: 10.1016/s0002-9149(97)00014-3.
Impaired functional capacity is common in patients with mitral regurgitation (MR), but the determinants of functional capacity in patients with normal left ventricular (LV) function are unclear. Forty patients with chronic, isolated, nonrheumatic MR with no coronary artery disease underwent exercise echocardiography with continuous expired gas analysis. Cardiac output and regurgitant stroke volume were measured at rest and immediately after exercise by pulsed-wave Doppler echocardiography. For controls, 17 healthy volunteers without MR were also studied. Patients achieved a significantly lower VO2max compared with controls (25.6 +/- 7.7 vs 31.7 +/- 7.7 ml/kg/min, p = 0.008). VO2max showed better correlations with exercise cardiac output than with cardiac output at rest in both patients and controls. Multiple linear regression identified exercise cardiac output (partial r = 0.65), patient age (partial r = -0.56), and gender as independent determinants of VO2max (multiple R = 0.85, p <0.001). Cardiac output at rest, LV ejection fraction, regurgitant stroke volume, and fraction were not significant determinants. With exercise, the regurgitant stroke volume increased in 13 patients and decreased in 27 patients. The former 13 patients had a significantly lower exercise cardiac output (7.4 +/- 2.5 vs 9.4 +/- 2.6 L/min, p = 0.026). Patients who stopped exercise due to dyspnea (n = 7) had a significantly lower exercise cardiac output and VO2max compared with those who stopped due to fatigue (n = 33), with no differences in resting or exercise regurgitant volume. Patients with an increase in LV end-systolic volume with exercise (n = 8) also had a significantly lower exercise cardiac output (6.9 +/- 1.9 vs 9.2 +/- 2.7 L/min, p = 0.037) and showed a trend toward a lower VO2max (21 +/- 7.5 vs 26 +/- 6.4 ml/kg/min, p = 0.07). In patients with chronic MR, exercise cardiac output is the major determinant of VO2max. Regurgitant volume and fraction are not related to functional capacity. Limitations in functional capacity in these patients may be more related to a diminished cardiac reserve than to a large regurgitant volume.
二尖瓣反流（MR）患者中功能能力受损很常见，但左心室（LV）功能正常患者的功能能力决定因素尚不清楚。40例患有慢性、孤立性、非风湿性MR且无冠状动脉疾病的患者接受了运动超声心动图检查及连续呼出气体分析。通过脉冲波多普勒超声心动图在静息时和运动后即刻测量心输出量和反流搏出量。作为对照，还研究了17名无MR的健康志愿者。与对照组相比，患者的最大摄氧量（VO2max）显著降低（25.6±7.7 vs 31.7±7.7 ml/kg/min，p = 0.008）。在患者和对照组中，VO2max与运动心输出量的相关性均优于与静息心输出量的相关性。多元线性回归确定运动心输出量（偏相关系数r = 0.65）、患者年龄（偏相关系数r = -0.56）和性别是VO2max的独立决定因素（复相关系数R = 0.85，p <0.001）。静息心输出量、左室射血分数、反流搏出量和反流分数不是显著的决定因素。运动时，13例患者的反流搏出量增加，27例患者的反流搏出量减少。前13例患者的运动心输出量显著降低（7.4±2.5 vs 9.4±2.6 L/min，p = 0.026）。因呼吸困难而停止运动的患者（n = 7）与因疲劳而停止运动的患者（n = 33）相比，运动心输出量和VO2max显著更低，静息或运动时的反流容量无差异。运动时左室收缩末期容积增加的患者（n = 8）运动心输出量也显著降低（6.9±1.9 vs 9.2±2.7 L/min，p = 0.037），且VO2max有降低趋势（21±7.5 vs 26±6.4 ml/kg/min，p = 0.07）。在慢性MR患者中，运动心输出量是VO2max的主要决定因素。反流容量和反流分数与功能能力无关。这些患者功能能力的限制可能更多与心脏储备减少有关，而非与大量反流容量有关。
