Werther Evaldsson Anna, Ingvarsson Annika, Waktare Johan, Smith Gustav J, Thilén Ulf, Stagmo Martin, Roijer Anders, Rådegran Goran, Meurling Carl
Department of Clinical Sciences Lund, Cardiology, Lund University, Lund, Sweden.
The Section for Heart Failure and Valvular Disease, VO Heart and Lung medicine, Skane University Hospital, Lund, Sweden.
Clin Physiol Funct Imaging. 2018 Sep;38(5):763-771. doi: 10.1111/cpf.12477. Epub 2017 Oct 26.
Right ventricular (RV) dysfunction may be caused by either pressure or volume overload. RV function is conventionally assessed with echocardiography using tricuspid annular plane systolic excursion (TAPSE), RV fractional area change (RVFAC), tricuspid lateral annular systolic velocity (S') and RV index of myocardial performance (RIMP). The purpose of this study was to evaluate whether RV global longitudinal strain (RVGLS) and RV-free wall strain (RV-free) could add additional information to differentiate these two causes of RV overload.
The study enrolled 89 patients with an echocardiographic trans-tricuspid gradient >30 mmHg. Forty-five patients with pulmonary arterial hypertension or chronic thromboembolic pulmonary hypertension (pressure overload) were compared with 44 patients with an atrial septum defect (volume overload). RV size was larger in the volume group (P<0·05). TAPSE and S' were lower in the pressure group (P<0·05, P<0·01). RVFAC was lower in the pressure group (P<0·001) as well as RVGLS (-12·1 ± 3·3% versus -20·2 ± 3·4%, P<0·001) and RV-free (-12·9 ± 3·3% versus -19·4 ± 3·4%, P<0·001).
In this study, RVGLS and RV-free could more accurately discriminate RV pressure from volume overload than conventional measures. The reason could be that TAPSE and S' are unable to differentiate active deformation from passive entrainment caused by the left ventricle. The pressure group had evidence of marked RV hypertrophy despite standard functional parameters (TAPSE and S) within normal range. This would enhance the value of strain to more sensitively detect abnormal function. A cut-off value of below -16% for RVGLS and RV-free predicts RV pressure overload with high accuracy.
右心室（RV）功能障碍可能由压力或容量超负荷引起。传统上，通过超声心动图使用三尖瓣环平面收缩期位移（TAPSE）、右心室面积变化分数（RVFAC）、三尖瓣侧环收缩速度（S'）和右心室心肌性能指数（RIMP）来评估右心室功能。本研究的目的是评估右心室整体纵向应变（RVGLS）和右心室游离壁应变（RV-free）是否能提供额外信息以区分这两种右心室超负荷的原因。
本研究纳入了89例超声心动图显示三尖瓣跨瓣压差>30 mmHg的患者。45例患有肺动脉高压或慢性血栓栓塞性肺动脉高压（压力超负荷）的患者与44例患有房间隔缺损（容量超负荷）的患者进行了比较。容量组的右心室大小更大（P<0.05）。压力组的TAPSE和S'较低（P<0.05，P<0.01）。压力组的RVFAC较低（P<0.001），以及RVGLS（-12.1±3.3%对-20.2±3.4%，P<0.001）和RV-free（-12.9±3.3%对-19.4±3.4%，P<0.001）。
在本研究中，与传统测量方法相比，RVGLS和RV-free能更准确地区分右心室压力超负荷和容量超负荷。原因可能是TAPSE和S'无法区分由左心室引起的主动变形和被动牵拉。尽管标准功能参数（TAPSE和S）在正常范围内，但压力组有明显右心室肥厚的证据。这将提高应变值以更敏感地检测异常功能。RVGLS和RV-free低于-16%的截断值可高精度预测右心室压力超负荷。
