Department of Cardiovascular Medicine, University Hospitals Leuven, Leuven, Belgium;
Am J Physiol Heart Circ Physiol. 2014 Mar;306(6):H816-24. doi: 10.1152/ajpheart.00752.2013. Epub 2014 Jan 24.
Breathing-induced changes in intrathoracic pressures influence left ventricular (LV) and right ventricular (RV) volumes, the exact nature and extent of which have not previously been evaluated in humans. We sought to examine this "respiratory pump" using novel real-time cardiac magnetic resonance (CMR) imaging. Eight healthy subjects underwent serial multislice real-time CMR during normal breathing, breath holding, and the Valsalva maneuver. Subsequently, a separate cohort of nine subjects underwent real-time CMR at rest and during incremental exercise. LV and RV end-diastolic volume (EDV) and end-systolic volume (ESV) and diastolic and systolic eccentricity indexes were determined at peak inspiration and expiration. During normal breathing, inspiration resulted in an increase in RV volumes [RVEDV: +18 ± 8%, RVESV: +14 ± 12%, and RV stroke volume (SV): +21 ± 10%, P < 0.01] and an opposing decrease in LV volumes (P < 0.0001 for interaction). During end-inspiratory breath holding, RV SV decreased by 9 ± 10% (P = 0.046), whereas LV SV did not change. During the Valsalva maneuver, volumes decreased in both ventricles (RVEDV: -29 ± 11%, RVESV: -16 ± 14%, RV SV: -36 ± 14%, LVEDV: -22 ± 17%, and LV SV: -25 ± 17%, P < 0.01). The reciprocal effect of respiration on LV and RV volumes was maintained throughout exercise. The diastolic and systolic eccentricity indexes were greater during inspiration than during expiration, both at rest and during exercise (P < 0.0001 for both). In conclusion, ventricular volumes oscillate with respiratory phase such that RV and LV volumes are maximal at peak inspiration and expiration, respectively. Thus, interpretation of RV versus LV volumes requires careful definition of the exact respiratory time point for proper interpretation, both at rest and during exercise.
呼吸引起的胸腔内压力变化会影响左心室 (LV) 和右心室 (RV) 的容积，但其在人体中的具体性质和程度尚未得到评估。我们试图使用新型实时心脏磁共振 (CMR) 成像来检查这种“呼吸泵”。8 名健康受试者在正常呼吸、屏气和瓦尔萨尔瓦动作期间接受了连续多层实时 CMR 检查。随后，另一组 9 名受试者在休息和递增运动时接受了实时 CMR 检查。在吸气和呼气的峰值时，确定 LV 和 RV 的舒张末期容积 (EDV)、收缩末期容积 (ESV)、舒张期和收缩期偏心指数。在正常呼吸时，吸气导致 RV 容积增加 [RVEDV：+18 ± 8%，RVESV：+14 ± 12%，RV 每搏量 (SV)：+21 ± 10%，P < 0.01]，而 LV 容积则相反减少（交互作用 P < 0.0001）。在吸气末屏气时，RV SV 减少了 9 ± 10%（P = 0.046），而 LV SV 没有变化。在瓦尔萨尔瓦动作期间，两个心室的容积都减少（RVEDV：-29 ± 11%，RVESV：-16 ± 14%，RV SV：-36 ± 14%，LVEDV：-22 ± 17%，LV SV：-25 ± 17%，P < 0.01）。呼吸对 LV 和 RV 容积的这种相互影响在整个运动过程中保持不变。在休息和运动时，吸气时的舒张期和收缩期偏心指数均大于呼气时（均 P < 0.0001）。结论是，心室容积随呼吸相而波动，使得 RV 和 LV 容积在吸气和呼气的峰值时分别达到最大。因此，在休息和运动时，要正确解释 RV 与 LV 容积，需要仔细定义确切的呼吸时间点。
