The role of contrast enhanced transesophageal echocardiography in the diagnosis and in the morphological and functional characterization of acute aortic syndromes

Comparison between transthoracic echocardiography and transoesophageal echocardiography in the diagnosis of acute aortic dissection from an emergency perspective. A systematic review and meta-analysis

Background

Acute aortic dissection (AAD) is a life-threatening medical condition with high early fatality. Therefore, a prompt and precise diagnosis, which can be achieved through invasive and non-invasive techniques is vital. Echocardiography, unlike MRI and CT, is accessible in emergency units and bedside-compatible. The recommended echocardiographic techniques for AAD are transthoracic and transoesophageal echocardiography (TTE and TOE). Therefore, our review compares their diagnostic roles in AAD.

Methods

Studies relevant to our topic were attained through a database search and manual scrutiny of references lists of articles obtained from the electronic databases. The Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2) has been used for quality assessment. All quantitative analyses were performed using either STATA 16 or Comprehensive Meta-Analyst software.

Results

The search strategy yielded 1,798 articles, of which only 11 were eligible for inclusion. Our subgroup analysis showed that conventional TTE had a sensitivity and specificity of 85.35% and 84.51% for the diagnosis of Stanford type A AAD and was 45.89% sensitive and 87.05% specific for the diagnosis of type B AAD. However, the subgroup analysis shows that contrast-enhancement of TTE results in a sensitivity and specificity of 93.30% and 97.60% for diagnosis of type A AAD, and 83.60% and 94.50% for diagnosis of type B AAD, respectively. On the other hand, conventional TOE was 93.64% sensitive and 95.50% specific for the diagnosis of type A AAD, 99.80% sensitive and 99.87% specific for the diagnosis of type B AAD. Moreover, our analyses show that TTE has pooled false negative and positive rates of 28.6% and 18.6%, while TOE has shown false negative and positive rates of 2.4% and 4.3%, respectively.

Conclusion

TOE is the more favorable diagnostic tool for AAD diagnosis than TTE. However, it cannot be used as a stand-alone diagnostic tool since misdiagnosis cases are being reported. Contrast-enhanced TTE can also diagnose AAD since it provides similar results to conventional TOE.

ACR Appropriateness Criteria® Suspected Acute Aortic Syndrome

Acute aortic syndrome (AAS) includes the entities of acute aortic dissection, intramural hematoma, and penetrating atherosclerotic ulcer. AAS typically presents with sudden onset of severe, tearing, anterior, or interscapular back pain. Symptoms may be dominated by malperfusion syndrome, due to obstruction of the lumen of the aorta and/or a side branch when the intimal and medial layers are separated. Timely diagnosis of AAS is crucial to permit prompt management; for example, early mortality rates are reported to be 1% to 2% per hour after the onset of symptoms for untreated ascending aortic dissection. The appropriateness assigned to each imaging procedure was based on the ability to obtain key information that is used to plan open surgical, endovascular, or medical therapy. This includes, but is not limited to, confirming the presence of AAS; classification; characterization of entry and reentry sites; false lumen patency; and branch vessel compromise. Using this approach, CT, CTA, and MRA are all considered usually appropriate in the initial evaluation of AAS if those procedures include intravenous contrast administration. Ultrasound is also considered usually appropriate if the acquisition is via a transesophageal approach. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The usefulness of contrast-enhanced echocardiography in the diagnosis and management of intramural hematoma and aortic dissection: A case report

Contrast-enhanced transthoracic echocardiography (cTTE) plays an important role in the diagnosis of intramural hematoma (IMH) and aortic dissection (AD), and is also necessary for the adequate management from the assessment of findings. We hereby present an interesting case in which cTTE provides additional value over contrast-enhanced computed tomography (CT) in the diagnosis and the morphological characterization of IMH and AD. A 58-year-old man presented to the emergency department with intermittent chest pain. After emergency consultation, an enhanced CT scan showed an acute aortic intramural hematoma involving aortic arch and descending aorta. Nevertheless, the entry tear and false lumen flow direction were identified by cTTE, which suggested an acute type B AD.

Diagnosing Aortic Intramural Hematoma: Current Perspectives

Aortic intramural hematoma (AIH) is an entity within the acute aortic syndrome. Combination of a priori probability, clinical history, laboratory blood test and imaging techniques are the basis for diagnosis of AIH. This review is focused on all aspects related to diagnosis of patients with AIH, from clinical to imaging and analytical.

Clinical practice of contrast echocardiography: recommendation by the European Association of Cardiovascular Imaging (EACVI) 2017

Contrast echocardiography is widely used in cardiology. It is applied to improve image quality, reader confidence and reproducibility both for assessing left ventricular (LV) structure and function at rest and for assessing global and regional function in stress echocardiography. The use of contrast in echocardiography has now extended beyond cardiac structure and function assessment to evaluation of perfusion both of the myocardium and of the intracardiac structures. Safety of contrast agents have now been addressed in large patient population and these studies clearly established its excellent safety profile. This document, based on clinical trials, randomized and multicentre studies and published clinical experience, has established clear recommendations for the use of contrast in various clinical conditions with evidence-based protocols.

Aortic intramural hemorrhage: A distinct disease entity with mystery

Aortic intramural hemorrhage (IMH) is one of the disease processes that comprise the spectrum of acute aortic syndrome (AAS) with clinical manifestations and a mortality rate similar to those of classic aortic dissection (AD). However, IMH should be considered as a distinct disease entity rather than a precursor to classic dissection because of differences in their pathology, etiology, natural history, and imaging findings. Multidetector computed tomography (CT) is recommended as the first-line diagnostic imaging modality for IMH, but transesophageal echocardiography (TEE) and magnetic resonance imaging (MRI) are also helpful. There is still debate over the appropriate treatment of IMH. Medical treatment of type B IMH appears effective and safe, while surgical treatment is recommended for type A IMH. Thoracic endovascular aortic repair (TEVAR) is a promising treatment for selected patients, and more clinical evidence needs to be assembled.

Usefulness of contrast-enhanced transoesophageal echocardiography to guide thoracic endovascular aortic repair procedure

AIMS

Thoracic endovascular aortic repair (TEVAR) is commonly considered as a valid alternative to surgery. Endoleaks occurrence is one of the principal limitations of TEVAR. Transoesophageal echocardiography (TEE) is often adopted in adjunct to fluoroscopy and angiography (ANGIO) during stent-graft implantation. In the present study, we compare intraprocedural ANGIO, TEE, and contrast-enhanced TEE (cTEE), and we also evaluate their accuracy in early endoleaks detection and characterization.

METHODS AND RESULTS

Fifty-four patients with thoracic aortic disease suitable for TEVAR were prospectively enrolled in the study. After stent placement, the result of the procedure was assessed by ANGIO, TEE, and cTEE. The use of contrast (Sonovue, Bracco) significantly improved TEE quality (P = 0.0001). cTEE was superior in entry tears, false and true lumen and aneurysm thrombosis identification, and microtears and ulcer-like projections detection before stent deployment. After stent deployment, cTEE was more accurate than TEE and ANGIO in the detection of slow flow in the false lumen and in the aneurismal sac (P = 0.0001), and in the remaining flow identification (P = 0.0001). Notably, cTEE is more accurate in the endoleaks detection (P = 0.0001) and in the incomplete stent expansion diagnosis and need for a further balloon inflation (P 0.002), or a further stent implantation (P 0.006), compared with TEE and ANGIO.

CONCLUSION

TEVAR procedures are improved by the complimentary use of contrast fluoroscopy, multiplane TEE with Doppler flow interrogation, and cTEE. This triple imaging approach provides additional information in all phases of the procedure improving safety of stent-grafting and the procedural outcomes.

Update in acute aortic syndrome: intramural hematoma and incomplete dissection as new disease entities

Acute aortic syndrome is a relatively recent clinical entity. Non-invasive imaging methods, such as computed tomography and transesophageal echocardiography, have contributed significantly to the diagnosis of variant forms of classic aortic dissection, which have become important disease entities in acute aortic syndrome. Imaging findings may result in risk stratification and application of different treatment options, providing a rational approach to achieve a better outcome of this syndrome. This review will focus on the imaging characteristics of two important variant forms of classic aortic dissection, intramural hematoma and incomplete dissection, and the role of imaging methods in the evaluation of differences in the hemodynamic status of false lumens that contributes to patient prognosis.