The latest Echocardiographic Techniques - When and to whom?

By Stefanos Karagiannis, Head of the Department of Echocardiology (Ultrasound of the Heart), Athens Medical Center

By the “latest echocardiographic techniques", we basically refer to three-dimensional echocardiography, contrast echocardiography and the techniques of Strain-Global Strain and Strain Rate.

In addition, a relatively new technique is the Dynamic Ultrasound Cardiography (STRESS ECHO), which is used to diagnose and predict coronary heart disease and valvular diseases, as well as to check the viability of the myocardium.

1. 3D Echocardiography

The table shows the indications for the implementation of 3D Echocardiograph, based on the US and European guidelines. According to the guidelines, the 3D Echocardiograph is recommended in order to evaluate the volume and overall efficacy (ejection fraction) of the left ventricle, the anatomy and stenosis of the mitral valve, and to guide percutaneous operations. Accurate estimation of the volume of the left ventricle requires precise determination of the intracardiac limits of the left ventricle, which, however, is not always possible with two-dimensional (2D) Echocardiograph, due to the geometrical assumptions and the perspective reduction of the structures resulting from their projection. (foreshortening).

In a study of a fully automated intracardiac contour design program, telediastolic and telesystolic volume and ejection fraction were significantly correlated with magnetic resonance imaging measurements, while this technique was found to be accurate in several groups of patients with an ejection fraction of more than 50 or less than 50 or in patients with atrial fibrillation.

Compared to 2DE, RT3DE can, by planimetric measuring of the mitral valve in the short-axis, the 3D Echocardiograph can measure its orifice very well, accurately calculating the stenosis, position, thickening and degree of merging of the scallops and tendinous chords. Mitral prolapse, which is often overestimated or underestimated by two-dimensional Echocardiograph, may also be better evaluated.

3D Echocardiography is also recommended in percutaneous valvuloplasty and for guiding percutaneous mitral clip placement, percutaneous aortic valve placement, paravalvular leak blockage, atrial and interventricular septal defect occlusion and left atrial appendage occlusion. This has also reduced the exposure of patients to radiation.

2. Stress Echo Contrast Echocardiography:

Contrast agents have enhanced the diagnostic capability of echocardiography through the detection of intracardiac and myocardial perfusion.

Indications for Dynamic Echocardiography (STRESS ECHO) exist when two or more adjacent sections of the left ventricle are insufficiently visualized to diagnose segmental wall motion and thickening during rest and stress, to increase diagnostic accuracy.

The application of contrast agents and the evaluation of perfusion, defined as tissue capillary blood flow, play a key role in the diagnosis of coronary heart disease. This offers to Stress Echo increased sensitivity and specificity of 85% and 81% respectively.

3. Tissue Doppler Echocardiography and Strain – Global Strain – Speckle Tracking:

Tissue Doppler Echocardiography (TDE) is now an established method of diagnostic echocardiography, allowing the evaluation of myocardial movement with the Doppler method. In order to overcome two major disadvantages with the TDE method, the dependence of the maximum movement speed on the ultrasound projection angle and the simultaneous rotational movement and displacement of the heart during the cardiac cycle, the method of strain and strain rate were developed. The strain reflects the deformation of a structure and thus directly describes myocardial contraction / relaxation.

The strain rate is a strong indicator of left ventricular contractility. This technique can detect segmental diastolic asynchrony, while using the method of dynamic echocardiography with dobutamine (Stress Echo), the extent of myocardial viability can be estimated.

Global Strain is a semi-automated method of measuring strain and strain rate, which can measure elongated, circular and radial displacements. It is not dependent on the angle of progression of the echocardiographic beam, as opposed to tissue Doppler, and is useful in assessing systolic function in post-traumatic patients as well as in evaluating and monitoring patients undergoing chemotherapy. It is also an indicator of prognosis in chronic aortic valve insufficiency, hypertrophic cardiomyopathy, assessment of arrhythmogenic right ventricle, severe pulmonary hypertension, and asynchrony in exponential cardiomyopathy.

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