Transthoracic echocardiography: main views
A standard examination uses specific acoustic windows, each allowing the evaluation of specific cardiac structures:
- Parasternal short-axis views (Parasternal Short-Axis Views). The left ventricle is evaluated at three levels. At the basal level, the right ventricle, moderator band, and mitral valve with anterior and posterior leaflets are visible. At the mid-level, the papillary muscles are located within the left ventricular cavity. The apical level demonstrates four apical segments.
- Apical views (Apical Views). The apex of the heart (apex) is at the top of the screen, and the atria (atria) are at the bottom. The four-chamber view shows all chambers, the interatrial septum (with the fossa ovalis), and the pulmonary veins. The two-chamber view (90-degree rotation) displays the anterior and inferior walls. The five-chamber view additionally captures the aortic root and the left ventricular outflow tract.
- Subcostal views (Subcostal views). Performed from the subxiphoid approach. Indispensable after thoracic surgery and for evaluating the inferior vena cava.
- Suprasternal view (Suprasternal View). Visualizes the aortic arch, its branches (common carotid and left subclavian arteries), and the pulmonary artery from the suprasternal notch.
Assessment of the valve apparatus
Two-dimensional echocardiography combined with Doppler ultrasound is the optimal tool for studying valve function and structure, although the focus is most often on the aortic and mitral valves.
Aortic valve (AV) normally has three cusps: right coronary, left coronary, and non-coronary. In pathology, it can be bicuspid. A distinction is made between a true bicuspid valve and a form with fused cusps forming a seam — raphe.
Mitral valve (MV) is examined from apical four- and two-chamber approaches. Due to its complex saddle shape, it cannot be imaged "en face" (en face) in a single two-dimensional plane. For accurate assessment, the leaflets are divided into segments: the anterior leaflet consists of segments A1, A2, and A3, while the posterior leaflet includes scallops P1, P2, and P3.
Transoesophageal echocardiography (TOE)
When the standard transthoracic approach is limited, transoesophageal echocardiography (Trans-oesophageal echocardiography / TOE) is used. The oesophagus is located immediately adjacent to the posterior wall of the heart, providing an ideal acoustic window without interference.
Advantages of the technique:
- Ideally suited for assessing atrial structures (left atrial appendage, pulmonary veins).
- Allows precise understanding of the mechanisms of mitral regurgitation or stenosis thanks to multiplanar visualization of individual segments.
- Detailed display of the anatomy of the aortic valve cusps and right ventricular outflow tract in transverse and longitudinal sections.
The main disadvantage of the method is patient discomfort, which sometimes requires light sedation.
Three-dimensional echocardiography and diagnostic imaging
For more accurate diagnostics, two-dimensional echocardiography is supplemented with three-dimensional (3-D Echo). It is essential for identifying valve anatomy and their better spatial orientation relative to surrounding structures. However, the method has limitations: spatial and temporal resolution, as well as the quality of 3D data acquisition, still require improvement.
In addition to ultrasound, CT and MRI are actively used in cardiology. CT angiography (with prospective ECG gating and low radiation doses) is used to evaluate coronary arteries and diseased valves. Magnetic resonance imaging (CMR) is used for standardized quantitative assessment of ventricular volumes.
Briefly: answers to topical questions
Which anatomical structures are visualized in the parasternal short-axis view at the basal level?
In the parasternal short-axis view at the basal level, structures of the right ventricle and elements of the mitral valve are visualized.
The echocardiogram clearly identifies:
- Right ventricle (RV) — visualized along with the moderator band.
- Moderator band (M) — a muscular trabecula within the right ventricular cavity.
- Mitral valve (MV) — at this level, its anterior (MV aml) and posterior (MV pml) leaflets are clearly differentiated.
Which branches of the aortic arch can be visualized from the suprasternal approach?
From the suprasternal approach, performed from the suprasternal notch, the aortic arch and associated vascular structures are visualized.
The echocardiogram identifies:
- Aortic arch (Ao-Arch, Aortic arch)
- Ascending aorta (Ao-Asc, Ascending aorta)
- Descending aorta (Ao-Desc, Descending aorta)
- Common carotid artery (AC, Common carotid artery)
- Left subclavian artery (LSA, Left subclavian artery)
- Right pulmonary artery (RPA, Right pulmonary artery)
The suprasternal approach allows evaluation of the aortic arch, its major branching vessels, and the descending aorta.
For the assessment of which cardiac parameters and pathologies is magnetic resonance imaging (MRI) used?
Magnetic resonance imaging is used for accurate anatomical and functional assessment of the heart, as well as myocardial tissue characterization.
The method is used to evaluate the following parameters and pathologies:
- Myocardial viability — detection of post-infarction cardiosclerosis, necrosis, scars, and microvascular obstruction.
- Cardiac function — assessment of myocardial motion, valves, myocardial strain, and ventricular volumes.
- Cardiomyopathies — differential diagnosis of hypertrophic, dilated cardiomyopathy, Fabry disease, amyloidosis, sarcoidosis, and Takotsubo cardiomyopathy.
- Myocardial infarction complications and sources of embolism — visualization of aneurysms, intracavitary thrombi, and valve vegetations.
- Inflammatory processes — diagnosis of acute myocarditis and detection of myocardial oedema.
What pathological conditions are the main clinical indications for transoesophageal echocardiography (TOE)?
The main clinical situations for performing transoesophageal echocardiography are associated with the need for more detailed visualization of the valves and atria.
These include:
- Infective endocarditis — TOE is recommended for patients with a confirmed diagnosis or suspected infective endocarditis, especially if transthoracic echo is unrevealing, complications have developed, or intracardiac devices are present; it is also used in the diagnosis of prosthetic valve IE and to detect vegetations.
- Atrial fibrillation prior to cardioversion — in patients with chronic heart failure or dilated cardiomyopathy, TOE is performed to rule out left atrial appendage thrombosis prior to restoration of sinus rhythm.
- Assessment of valves and atria — used for detailed evaluation of aortic valve anatomy and atrial structures, as well as for a better understanding of the mechanisms of mitral regurgitation or stenosis.
- Mitral stenosis — TOE is used when transthoracic echo is uninformative, when left atrial appendage thrombosis is suspected, and prior to percutaneous mitral commissurotomy.
- Uninformative transthoracic echo — in dilated cardiomyopathy, TOE is recommended to clarify elements of structural and functional remodelling that are unreliably determined by transthoracic echo.
Which cardiac structures are visualized in the apical four-chamber view?
In the apical four-chamber view, all four chambers of the heart, as well as the valve apparatus and septa, are visualized.
The following structures are identified:
- Heart chambers — left (LV) and right (RV) ventricles, left (LA) and right (RA) atria.
- Valves — mitral (MV) and tricuspid (TV) valves.
- Myocardium and septa — septal (S) and lateral (L) myocardium, interatrial septum (IAS) including the septum primum (PS) and septum secundum with the fossa ovalis (FO/SS).
- Additional structures — moderator band (M) and left pulmonary veins (LPV).
Mitral valve leaflets are easy to remember by their initial letters: A (Anterior) — anterior, P (Posterior) — posterior. Each is divided into three segments (from 1 to 3).
Class and exam questions
What is the difference between the apical five-chamber view and the four-chamber view?
In the five-chamber view, the aorta is added as a "fifth chamber" to the left and right ventricles and both atria. The aortic valve and left ventricular outflow tract are also visualized in this view.
How to indirectly estimate right atrial pressure using ultrasound?
The subcostal approach is used for this purpose. The diameter of the inferior vena cava (IVC) is measured, and its inspiratory collapse (respiratory variation) is assessed.
Why is the mitral valve difficult to evaluate in a single 2D plane?
The mitral valve has a complex three-dimensional saddle shape. Because of this, it is impossible to image it completely in an en face position on a two-dimensional scan.
What else to study on this topic
- Anatomy of the interatrial septum: septum primum, septum secundum, and fossa ovalis
- Multiplanar TEE views: bicommissural and three-chamber views of the mitral valve
- Three-dimensional reconstruction of the aortic valve in open and closed states
- Detection of pericardial effusion using echocardiography
- Comparison of CT and MRI in the assessment of ventricular volumes
Other topics in the «Chest Radiology» section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.