From the Guidelines
For patients with suspected aortic dissection and hemodynamic instability, CT is recommended as the initial diagnostic imaging modality due to its wide availability, accuracy, and speed, as well as the extent of anatomic detail it provides 1. When considering the diagnosis of aortic dissection in unstable patients, it's crucial to prioritize imaging modalities that offer rapid and accurate assessment. The key characteristics of the ideal initial diagnostic tool include:
- Wide availability
- High accuracy
- Speed of imaging
- Detailed anatomic information Given these requirements, CT stands out as the preferred initial imaging modality for diagnosing aortic dissection in hemodynamically unstable patients, as supported by the 2022 ACC/AHA guideline for the diagnosis and management of aortic disease 1.
In clinical practice, the approach to diagnosing aortic dissection involves:
- Initial assessment with CT for its accuracy and speed
- Consideration of alternative imaging modalities like TEE and MRI if CT is not feasible or if additional detail is needed
- Integration of clinical assessment and risk scoring systems to aid in diagnosis, though these should not delay imaging
- Recognition that while biomarkers like D-dimer can support the diagnosis, they are not definitive and should be interpreted in the context of clinical suspicion and imaging findings.
The rationale behind choosing CT as the initial diagnostic approach is based on its ability to provide comprehensive imaging of the aorta quickly, which is critical in unstable patients where time is of the essence. Other imaging modalities, such as TEE and MRI, are valuable but may not be as readily available or as quick to perform as CT, making them secondary choices in the initial assessment of hemodynamically unstable patients suspected of having aortic dissection 1.
From the Research
Diagnosis of Aortic Dissection in Patients with Hemodynamic Instability
The diagnosis of aortic dissection in patients with hemodynamic instability requires a rapid and precise diagnosis. The following imaging modalities can be used:
- Transesophageal echocardiography (TEE) 2: TEE is a practical and sensitive method for diagnosing aortic dissection, especially in hemodynamically unstable patients.
- Computed tomography angiography (CTA) 3, 4, 5, 6: CTA is a rapid and accurate method for diagnosing aortic dissection, but may not be suitable for all patients.
- Magnetic resonance imaging (MRI) 2, 4, 6: MRI is a comprehensive and detailed evaluation of the thoracic aorta, but may not be practical in emergency situations.
- Point of care ultrasound (POCUS) 3: POCUS is a rapid and underutilized method for diagnosing aortic dissection, especially in patients with atypical presentations.
- Aortography 2: Aortography may be necessary in patients with clinical signs suggestive of organ ischemia and in whom coronary anatomy needs to be delineated before operation.
Imaging Modalities for Diagnosing Aortic Dissection
The choice of imaging modality depends on the patient's condition and the availability of equipment. The following factors should be considered:
- Sensitivity and specificity of the imaging modality
- Practicality and availability of the imaging modality
- Patient's hemodynamic stability
- Need for rapid diagnosis and treatment
Importance of Rapid Diagnosis
Rapid diagnosis and treatment of aortic dissection are crucial to improve patient outcomes. Delayed diagnosis and treatment can lead to increased mortality and morbidity 4, 6. Therefore, it is essential to choose an imaging modality that provides rapid and accurate diagnosis, such as TEE or CTA.