Olson Thomas P, Johnson Bruce D, Borlaug Barry A
Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic Rochester, Minnesota.
Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic Rochester, Minnesota.
JACC Heart Fail. 2016 Jun;4(6):490-8. doi: 10.1016/j.jchf.2016.03.001.
The purpose of this study was to compare measures of gas exchange at rest and during exercise in patients with heart failure and preserved ejection fraction (HFpEF) with age- and sex-matched control subjects.
Patients with HFpEF display elevation in left heart pressures, but it is unclear how this affects pulmonary gas transfer or its determinants at rest and during exercise.
Patients with HFpEF (n = 20) and control subjects (n = 26) completed a recumbent cycle ergometry exercise test with simultaneous measurement of ventilation and gas exchange. Diffusion of the lungs for carbon monoxide (DLCO) and its subcomponents, pulmonary capillary blood volume (VC) and alveolar-capillary membrane conductance (DM), were measured at rest, and matched for low-intensity (20 W) and peak exercise. Stroke volume was measured by transthoracic echocardiography to calculate cardiac output.
Compared with control subjects, patients with HFpEF displayed impaired diastolic function and reduced exercise capacity. Patients with HFpEF demonstrated a 24% lower DLCO at rest (11.0 ± 2.3 ml/mm Hg/min vs. 14.4 ± 3.3 ml/mm Hg/min; p < 0.01) related to reductions in both DM (18.1 ± 4.9 ml/mm Hg/min vs. 23.1 ± 9.1 ml/mm Hg/min; p = 0.04), and VC (45.9 ± 15.2. ml vs. 58.9 ± 16.2 ml; p = 0.01). DLCO was lower in patients with HFpEF compared with control subjects in all stages of exercise, yet its determinants showed variable responses. With low-level exercise, patients with HFpEF demonstrated greater relative increases in VC, coupled with heightened ventilatory drive and more severe symptoms of dyspnea compared with control subjects. At 20-W exercise, DM was markedly reduced in patients with HFpEF compared with control subjects. From 20 W to peak exercise, there was no further increase in VC in patients with HFpEF, which in tandem with reduced DM, led to a 30% reduction in DLCO at peak exercise (17.3 ± 4.2 ml/mm Hg/min vs. 24.7 ± 7.1 ml/mm Hg/min; p < 0.01).
Subjects with HFpEF display altered pulmonary function and gas exchange at rest and especially during exercise, which contributes to exercise intolerance. Novel therapies that improve gas diffusion may be effective to improve exercise tolerance in patients with HFpEF.
本研究旨在比较射血分数保留的心力衰竭（HFpEF）患者与年龄和性别匹配的对照者在静息和运动时的气体交换指标。
HFpEF患者左心压力升高，但尚不清楚这如何影响静息和运动时的肺气体交换或其决定因素。
HFpEF患者（n = 20）和对照者（n = 26）完成了卧位蹬车运动试验，同时测量通气和气体交换。在静息状态下测量肺一氧化碳弥散量（DLCO）及其子成分肺毛细血管血容量（VC）和肺泡-毛细血管膜传导率（DM），并在低强度（20 W）和运动峰值时进行匹配。通过经胸超声心动图测量每搏输出量以计算心输出量。
与对照者相比，HFpEF患者舒张功能受损且运动能力降低。HFpEF患者静息时的DLCO降低24%（11.0±2.3 ml/mm Hg/min对14.4±3.3 ml/mm Hg/min；p<0.01），这与DM（18.1±4.9 ml/mm Hg/min对23.1±9.1 ml/mm Hg/min；p = 0.04）和VC（45.9±15.2 ml对58.9±16.2 ml；p = 0.01）的降低有关。在运动的各个阶段，HFpEF患者的DLCO均低于对照者，但其决定因素表现出不同的反应。与对照者相比，在低强度运动时，HFpEF患者的VC相对增加更大，同时通气驱动力增强且呼吸困难症状更严重。在20 W运动时，HFpEF患者的DM与对照者相比明显降低。从20 W到运动峰值，HFpEF患者的VC没有进一步增加，这与DM降低一起导致运动峰值时DLCO降低30%（17.3±4.2 ml/mm Hg/min对24.7±7.1 ml/mm Hg/min；p<0.01）。
HFpEF患者在静息时尤其是运动时肺功能和气体交换发生改变，这导致运动不耐受。改善气体弥散的新疗法可能有效改善HFpEF患者的运动耐量。
