Echocardiography techniques

Main approaches and imaging views

Echocardiography is the most commonly performed imaging modality in the assessment of non-ischemic acquired heart disease. Due to its portability and lack of ionizing radiation, the method has become the first-line standard.

In clinical practice, there are two main approaches for conducting the examination:

• Transthoracic (transthoracic) — a standard examination through the anterior chest wall.
• Transoesophageal (transoesophageal) — performed by inserting a specialized probe into the esophagus. This avoids acoustic interference from the ribs and lungs, providing highly detailed images of posterior structures.

Modern devices allow imaging in both standard 2D and 3D modes, providing spatial perception of complex valve and chamber anatomy.

The role of Doppler ultrasound

Doppler ultrasound significantly expands the functionality of basic ultrasound, allowing not only visualization of structure but also assessment of blood flow physics within the heart.

• Color Doppler flow mapping: Essential for rapid detection of pathological flows. For example, in aortic regurgitation, the regurgitant flow is visualized as a broad jet (jet).
• Continuous-wave Doppler (continuous-wave Doppler): Used for precise quantitative measurements. It measures blood flow velocity, including upstream and downstream of stenotic regions (e.g., in aortic coarctation). By applying the modified Bernoulli equation (modified Bernoulli equation), a specialist can calculate the pressure gradient and predict the degree of stenosis.

In severe aortic regurgitation, continuous-wave Doppler shows a steep deceleration slope, reflecting a rapid drop in diastolic pressure. The pressure half-time (pressure half-time) in such cases is less than 250 ms.

Clinical applications

Echocardiography methods are used at all stages of cardiac patient management:

1. Pre-resynchronization therapy evaluation (resynchronisation therapy): Echo with Doppler, alongside ECG, is routinely used for initial patient selection, although MRI is now increasingly employed for more precise identification of scar tissue in the inferior wall.
2. Diagnosis of congenital heart disease in children: In infants, transthoracic ultrasound excels at visualizing aortic coarctation and associated anomalies.
3. Triage before other imaging studies: If a patient is scheduled for CT angiography, but an echo has not been performed recently, the CT results may require a subsequent ultrasound follow-up to clarify the hemodynamic significance of detected leaflet closure defects.

Limitations of the method

Despite its versatility, echocardiography has a number of objective limitations compared to other imaging modalities (CT and MRI):

• Assessment of thrombosis: The method may yield false-negative results in detecting thrombi in hard-to-reach areas, such as near the cardiac apex. In such cases, contrast-enhanced cardiac magnetic resonance imaging offers the highest sensitivity.
• Age limitations in coarctation: While transthoracic imaging is highly informative in infants, visualizing aortic coarctation by ultrasound is severely hindered in adults and older children, making MRI the method of choice.
• Reproducibility of results: During serial monitoring of ventricular function in patients with cardiomyopathies, echo is inferior to MRI in terms of accuracy and operator independence.

Class and exam questions

What else to study on this topic

• Myocardial MRI mapping: quantitative assessment of T1 and T2 relaxation times.
• Application of 4D-flow MRI to analyze blood flow in congenital heart defects.
• Quantitative assessment of aortic regurgitation using cine-MRI.
• CT semiotics of aortic root anomalies and paravalvular abscesses.
• Chest radiography: evaluation of pulmonary hemodynamics and cardiac chamber sizes.

Other topics in the «Chest Radiology» section

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