Strain Imaging: An Everyday Tool for the Perioperative Echocardiographer

Strain analysis allows for global and regional analysis of myocardial function and has been shown to be an independent predictor of outcomes after cardiac surgery. Strain imaging offers advantages over traditional EF measurements in that it is relatively angle independent, it is less dependent upon loading conditions, it is reproducible, it does not rely on geometric assumptions, and it can detect subclinical systolic dysfunction. Limitations of strain analysis include high temporal resolution requirements, a strong dependence on image quality, and inter-vendor variability. In addition, there is a paucity of data on the intraoperative applications of strain. The ASE has defined a global longitudinal strain of -20% measured by transthoracic echocardiography to be considered normal, with less negative values considered abnormal. Presently, there are no published guidelines on the normal values of strain with transesophageal echocardiography (TEE). However, multiple studies have shown that a reduction in intraoperative strain assessed with TEE has been shown to be an independent predictor of complications during cardiac surgery. Accordingly, further incorporation of intraoperative strain analysis with TEE could aid in prognostication for patients undergoing cardiac surgery. As perioperative strain analysis continues to advance, an understanding of these concepts is imperative for perioperative echocardiographers. It is the authors' goal to show that strain imaging can provide a reliable and objective measure that can be performed in real time to aid in decision-making and perioperative risk stratification.