Why is an echocardiogram (echo) necessary in the diagnosis of aortic dissection?

From the Guidelines

Echocardiography is crucial in the diagnosis of aortic dissection as it allows for rapid visualization of the dissection flap, determination of the type of dissection, and evaluation of complications, guiding immediate management decisions and improving patient outcomes. According to the most recent and highest quality study 1, echocardiography plays a vital role in the diagnosis and management of aortic dissection. The study highlights the importance of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in visualizing the intimal flap, identifying the true and false lumens, and detecting complications such as aortic regurgitation, pericardial effusion, or cardiac tamponade.

Some key points to consider when using echocardiography in aortic dissection include:

• TTE is typically performed first due to its non-invasive nature and quick availability, but TEE provides superior visualization of the thoracic aorta with sensitivity and specificity exceeding 95% 1
• A normal TTE examination cannot exclude aortic dissection, and TEE is a more sensitive diagnostic procedure 1
• Reverberation artifacts are a major pitfall with echocardiography, and the imager must be experienced to avoid misdiagnosis 1
• Echo findings guide immediate management decisions, including whether emergency surgery is needed (typically for Type A dissections) or if medical management is appropriate (often for uncomplicated Type B) 1

In terms of specific recommendations, the European Association of Cardiovascular Imaging and the Acute Cardiovascular Care Association recommend the use of echocardiography in acute cardiovascular care, including aortic dissection 1. The guidelines emphasize the importance of early diagnosis and prompt management in improving patient outcomes. Overall, echocardiography is a valuable tool in the diagnosis and management of aortic dissection, and its use should be guided by the most recent and highest quality evidence.

From the Research

Importance of Echocardiogram in Diagnosing Aortic Dissection

• An echocardiogram, particularly transesophageal echocardiography (TEE), is a crucial diagnostic tool for aortic dissection due to its ability to provide a complete overview of the thoracic aorta and its branching vessels 2.
• TEE can identify the true lumen for cannulation, assure true lumen perfusion, and assess the structural integrity and perfusion of the innominate and carotid arteries during surgical repair 2.
• The use of modified TEE, which involves placing a fluid-filled balloon in the trachea, can help overcome the "blind-spot" caused by air in the trachea, allowing for better visualization of the thoracic aorta 2.

Comparison with Other Diagnostic Methods

• TEE has been compared to magnetic resonance imaging (MRI) in diagnosing thoracic aortic dissection, with both methods showing high sensitivity, but MRI having higher specificity, particularly in detecting lesions in the ascending aorta 3.
• Transthoracic echocardiography (TTE) is also a valuable tool in the emergency assessment of acute aortic syndromes, although its diagnostic sensitivity is suboptimal, and a negative result does not exclude aortic dissection 4.
• Echocardiography has been shown to have high accuracy in diagnosing aortic dissection, with sensitivity and specificity of 99% and 98%, respectively, in a multicenter study 5.

Perioperative Use of Echocardiography

• Perioperative TEE plays a pivotal role in the management of aortic dissection, assisting with quantifying the severity of disease, facilitating surgical considerations, and guiding echocardiography-guided surgery 6.
• Echocardiography can help identify key presenting features that affect mortality and improve patient outcomes by allowing for appropriately timed surgery 6.