Strain Echocardiography in Acute Cardiovascular Diseases

Abstract

Echocardiography has become a critical tool in the evaluation of patients presenting to the emergency department (ED) with acute cardiovascular diseases and undifferentiated cardiopulmonary symptoms. New technological advances allow clinicians to accurately measure left ventricular (LV) strain, a superior marker of LV systolic function compared to traditional measures such as ejection fraction, but most emergency physicians (EPs) are unfamiliar with this method of echocardiographic assessment. This article discusses the application of LV longitudinal strain in the ED and reviews how it has been used in various disease states including acute heart failure, acute coronary syndromes (ACS) and pulmonary embolism. It is important for EPs to understand the utility of technological and software advances in ultrasound and how new methods can build on traditional two-dimensional and Doppler techniques of standard echocardiography. The next step in competency development for EP-performed focused echocardiography is to adopt novel approaches such as strain using speckle-tracking software in the management of patients with acute cardiovascular disease. With the advent of speckle tracking, strain image acquisition and interpretation has become semi-automated making it something that could be routinely added to the sonographic evaluation of patients presenting to the ED with cardiovascular disease. Once strain imaging is adopted by skilled EPs, focused echocardiography can be expanded and more direct, phenotype-driven care may be achievable for ED patients with a variety of conditions including heart failure, ACS and shock.

Figure 1

Apical 4-chamber image demonstrating semi-automated tracing of the endocardial border using two-dimensional speckle-tracking software. Depth is minimized excluding part of the left atrium in order to maximize frame rate.

Figure 2

Quad display of an apical 2-chamber image demonstrating three different ways to depict left ventricular (LV) longitudinal strain. Images are taken from a patient with a history of heart failure with preserved ejection fraction. Top left image is a 2D depiction showing the color-coding for each LV segment and the global longitudinal strain in the 2-chamber plane (GS=−10.2%); bottom left image displays the strain for each of the 6 LV segments in the 2-chamber plane; bottom right shows the anatomical M-mode display for the 2-chamber plane with each LV segment color coded on the y-axis and the instantaneous strain being depicted using deeper red hues to represent more negative strain and deeper blue hues to represent more positive strain; top right displays strain (y-axis) plotted over time (x-axis) for each LV segment with a color-coded linear graphical display.

Figure 3

Bullseye map of left ventricular strain. Impaired longitudinal strain of the basal inferior wall is shown in a patient with an indeterminate troponin who would go on to develop a non-ST elevation myocardial infarction (NSTEMI).

Figure 4

Baseline echocardiogram in a patient with acute hypertensive pulmonary edema. Quad view demonstrating apical 4-chamber, 2-chamber and long axis images with a bullseye map. Global longitudinal strain is −7.1%. There is significant dyskinesis in the anteroseptal, anterior and lateral segments.

Figure 5

Follow-up echocardiogram of patient from Figure 4 24 hours after presentation. Quad view, Global longitudinal strain is now −13.5%. Anteroseptal, anterior and lateral wall dyskinesis has resolved following afterload reduction.