Geert Kleinnibbelink

Chapter 1 24 Speckle tracking echocardiography Speckle tracking echocardiography (STE) is a relatively novel method to assess ventricular function and was first described by Kaluzynski et al. 50 and D’Hooge et al. 51 in 2001. Speckles are small areas of increased echogenicity caused by reflections, refraction and scattering of ultrasoundwaves. Each region of themyocardiumhas a unique speckle pattern that allows the region to be traced from one frame to the next, and therefore allows the calculation of deformation, also referred to as strain, of the myocardium. Deformation in the myocardial wall can be calculated in three directions; radial, circumferential and longitudinal. Because of the complex geometry and the alignment of muscle fibers in the RV, longitudinal lateral / free wall strain is commonly used to assess RV function using speckle tracking echocardiography. 52 Strain imaging has shown to be a valuable measurement of RV function and has the advantage that it is less angle and load dependent compared to the conventional indices. 48 More specifically, RV strain imaging provides both diagnostic and prognostic information on cardiac diseases including RV focused diseases as pulmonary hypertension. 53, 54 In line with a majority of work in the heart, most studies have strongly focused on the potential role of speckle tracking in the LV. Especially for the RV this measure may be of added value, supported by the relatively poor ability of currently used measures of RV function to detect abnormalities in the RV (such as with PAH). Therefore, one of the aims of this thesis is to explore the potential role for RV longitudinal strain in prediction disease progression of pulmonary artery hypertension. Strain-area loop Recent innovation in echocardiography provided novel and improved opportunities to assess RV function. In that speckle tracking echocardiography allows for evaluation of myocardial deformation, it also provides the ability to detect subclinical groups and hence greater prognostic value compared to conventional echocardiography. 54 Recently, a novel method, developed by our group at the Liverpool John Moores University, United Kingdom, was introduced to assess the interaction between deformation (i.e. related to pressure generation) and area (i.e. related to volume) across the cardiac cycle. 49 This novel method, the strain-area loop, provides simultaneous temporal relationships of the RV structure and longitudinal function. In other words, it elucidates, non-invasively, the structure function relationship throughout systole and diastole and provides estimates of