The role of strain and strain rate imaging in the assessment of regional myocardial function
- I. interní-kardioangiologická klinika, Fakultní nemocnice u sv. Anny, Brno, Česká republika
The purpose of this paper is to provide a summary of the current knowledge of the role of strain and strain rate imaging in the assessment of regional myocardial function. Despite the impressive advances made by echocardiography over the last decade, the majority of echocardiographic methods utilized so far to determine regional myocardial function has had major limitations such as the absence of quantification, the impact of extracardiac factors which modify the character and velocity of cardiac motion, etc. Assessment of myocardial deformation (strain) and the rate of deformation (strain rate) represent a new approach devoid of the majority of limitations encountered so far. Strain and strain rate analysis is derived from the determination of myocardial velocities by color Doppler tissue echocardiography. Strain rate is the difference in myocardial velocities at two points divided by the distance between them and expresses the rate of deformation. Strain in the corresponding myocardial area can be calculated by integrating strain rate and characterizes relative tissue deformation. Unlike Doppler tissue velocities, affected by rotational and translational motion of the whole heart, strain and strain rate are independent of the overall heart motion. They are also less influenced by the effect of tethering. These facts probably account for the higher sensitivity of strain and strain rate in evaluating regional myocardial function as compared with Doppler tissue velocities. The strain and strain rate parameters can be used to quantify regional myocardial systolic and diastolic function, to detect myocardial ischemia (including early stages of ischemia), and to assess myocardial contractile synchrony. Analysis of strain rate and strain curves at rest and during dobutamine infusion allows to distinguish different pathological conditions resulting in left ventricular dysfunction including acute ischemia, myocardial stunning, and a scar. At present, every effort is made to eliminate or suppress some limitations (mainly the noisy echo signal in patients with a suboptimal acoustic window) which prevent this method from finding widespread use. Despite this, both strain and strain rate have a great potential to become accurate, noninvasive, and widely available methods for regional myocardial function assessment.
Keywords: Echocardiography; Strain; Strain rate
Published: February 1, 2005 Show citation