Norgård G, Johannessen K A
Department of Clinical Physiology, Haukeland Hospital, Bergen, Norway.
Clin Physiol. 1993 Jul;13(4):373-83. doi: 10.1111/j.1475-097x.1993.tb00337.x.
To assess possible factors affecting the variability of digitized left ventricular M-mode echocardiograms, the influence of respiration and the variability due to different beats and observers were analysed in 11 healthy subjects and 11 patients with repaired tetralogy of Fallot. Left ventricular end-diastolic dimension (LVEDD) decreased from end-expiration to end-inspiration in the healthy subjects, but not in the patients. The maximal rate of dimension change decreased in both healthy subjects and patients from end-expiration to end-inspiration. The beat-to-beat variability assessed by the coefficient of variation (CV,%) between measurements of one cardiac cycle was twice the CV for three cycles, whereas the CV for three and five cardiac cycles was not different. The CV for intraobserver variability was less than 5.0% for dimensions and less than 13.0% for the rates of dimension change, whereas the interobserver variability had CV of 17.1% for rates of dimension changes. The influence of respiration and different observers on the variability of LV end-systolic dimension and shortening fraction was larger in the patients than in the healthy subjects. Thus, to obtain optimal technique for analysis of digitized LV M-mode echocardiograms in serial patient studies, the number of observers should be kept at a minimum and at least 3 beats at end-expiration should be used.
为评估影响数字化左心室M型超声心动图变异性的可能因素，对11名健康受试者和11名法洛四联症修复术后患者分析了呼吸的影响以及不同心搏和观察者所致的变异性。健康受试者的左心室舒张末期内径（LVEDD）从呼气末到吸气末减小，而患者则不然。从呼气末到吸气末，健康受试者和患者的最大内径变化率均降低。通过一个心动周期测量之间的变异系数（CV，%）评估的心搏间变异性是三个周期CV的两倍，而三个和五个心动周期的CV无差异。观察者内变异性的CV对于内径小于5.0%，对于内径变化率小于13.0%，而观察者间变异性对于内径变化率的CV为17.1%。患者中呼吸和不同观察者对左心室收缩末期内径和缩短分数变异性的影响大于健康受试者。因此，为在系列患者研究中获得分析数字化左心室M型超声心动图的最佳技术，观察者数量应保持在最少，并且应使用呼气末至少3个心搏。
