Transesophageal echocardiography in the diagnosis of diseases of the thoracic aorta: part 1. Aortic dissection, aortic intramural hematoma, and penetrating atherosclerotic ulcer of the aorta

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.

Hemodynamic monitoring using trans esophageal echocardiography in patients with shock

Circulatory shock is a life-threatening condition responsible for inadequate tissue perfusion. The objectives of hemodynamic monitoring in this setting are multiple: identifying the mechanisms of shock (hypovolemic, distributive, cardiogenic, obstructive); choosing the adequate therapeutic intervention, and evaluating the patient's response. Echocardiography is proposed as a first line tool for this assessment in the intensive care unit. As compared to trans-thoracic echocardiography (TTE), trans-esophageal echocardiography (TEE) offers a better echogenicity and is the best way to evaluate deep anatomic structures. The therapeutic implication of TEE leads to frequent changes in clinical management. It also allows depicting sources of inaccuracy of thermodilution-based hemodynamic monitoring. It is a semi invasive tool with a low rate of complications. The first step in the hemodynamic evaluation of shock is to characterize the mechanisms of circulatory failure among hypovolemia, vasoplegia, cardiac dysfunction, and obstruction. Echocardiographic evaluation includes evaluation of LV systolic and diastolic function, as well as RV function, pericardium, measure of stroke volume and cardiac output, and evaluation of hypovolemia and fluid responsiveness. TEE can be used as a semi-continuous monitoring tool and can be repeated before and after therapeutic interventions (vasopressors, inotropes, fluid therapy, specific treatment such as pericardial effusion evacuation) to evaluate efficacy and tolerance of therapeutic interventions. In conclusion, TEE plays an important role in the management of circulatory failure when TTE is not enough to answer to the questions, although it is not a continuous tool of monitoring. TEE results must be integrated in a global evaluation, the first step being clinical examination. Whether TEE-directed therapy and close hemodynamic monitoring of shock has an impact on outcome remains debated.

Ultrasound imaging artifacts: How to recognize them and how to avoid them

Echocardiography has become a critical tool in clinical cardiology in evaluating cardiac physiology and diagnosing cardiac disease states. However, imaging artifacts are commonly encountered and often lead to misdiagnoses of life-threatening diseases, such as aortic dissection and ventricular thrombus. It is, thus, critical for clinicians to understand these artifacts to avoid these misdiagnoses and protect patients from undue intervention. Artifacts can be broken down into two categories: those from violation of ultrasound system assumptions and those from interference by external equipment and devices. This review article discusses the most commonly encountered artifacts by category, explains their physical mechanisms, elaborates on their most common presentations, and instructs clinicians on how to avoid their misinterpretation.

Transesophageal Echocardiographic Guidance of Thoracic Aortic Stent-Graft Implantation

Purpose:

To evaluate the efficacy of intraoperative transesophageal echocardiography (TEE) as an adjunctive measure in guiding the implantation of endoluminal stent-grafts in the thoracic aorta.

Methods:

TEE was used in 21 of 30 patients (27 men; median age 70 years; range 19–77) undergoing implantation of Excluder or Talent stent-grafts for management of 11 type B aortic dissections, 7 thoracic aortic aneurysms, 2 traumatic thoracic aortic ruptures, and an aortic coarctation. We evaluated the ability of TEE to provide evidence of (1) correct placement of the guidewire within the true lumen, (2) reduction in blood flow in the false lumen following stent deployment, and (3) early complications.

Results:

Definite identification of the true lumen and a reliable evaluation of the position of the stent-graft guidewire during advancement were possible in all patients. Reduction of blood flow within the false lumen following deployment of the stent-graft was visualized in >70% of patients with aortic dissection. In the patient with aortic coarctation, TEE recognized the acute onset of aortic dissection following stent dilation, which resulted in immediate management with an additional stent.

Conclusions:

The intraoperative use of TEE in the implantation of stent-grafts in the thoracic aorta is not significantly invasive and is easily employed. It permits excellent evaluation of the correct placement of the stent guidewire and, in patients with aortic dissection, intraoperatively visualizes effective blood flow reduction in the false lumen following stent-graft deployment. Its ability to recognize early complications may indicate the need for additional maneuvers during the surgical procedure.

Natural history and outcome of patients with intramural hematomas and penetrating aortic ulcers

All pathologies of acute aortic syndromes should be precisely diagnosed for prompt therapy. Intramural hematomas, as well as penetrating ulcers can be encountered in these patients. Presentations, clinical scenarios, and proper management are outlined in this review, which sums up available current literature to provide the vascular specialist with an adequate understanding of these unique syndromes.

Transesophageal echocardiography: a complementary view of the heart

Transesophageal echocardiography has been widely used as a diagnostic tool during the past two decades to detect cardiac abnormalities that are not visible or poorly visible with transthoracic echocardiography. At present, transesophageal echocardiography is a cornerstone of modern diagnosis of several cardiac diseases, providing diagnostic, prognostic and therapeutic information. In this review, the present status of transesophageal echocardiography not only as a diagnostic tool, underlining its effects on clinical decision making, but also as a monitoring adjunct for many interventional cardiac procedures is examined.

Acute aortic dissection

Acute aortic dissection is an uncommon but lethal cause of acute chest, back, and abdominal pain. Establishing a timely diagnosis is paramount, as mortality from acute aortic dissection rises by the hour. Physical findings are protean and may include acute aortic valve insufficiency, peripheral pulse deficits, a variety of neurologic deficits, or end-organ ischemia. The keys to establishing a timely diagnosis are maintaining a high index of suspicion and quickly obtaining a diagnostic study. CT angiography, magnetic resonance imaging, transesophageal echocardiography, and, to a lesser extent, aortography are all highly accurate imaging modalities. The choice of study should be driven by the clinical stability of the patient, the information required and the resources available at presentation. Proximal dissections are surgical emergencies, but distal dissections are generally treated medically. Endovascular stents are gaining favor for use in the repair of both acute and chronic distal dissections. Long-term outcome data for endovascular stenting are still limited, and it remains unclear when stenting should be favored over surgery or medical therapy.

Comment, quand et pourquoi réaliser une imagerie de l’aorte thoracique chez l’adulte ?

CT, MRI and transesophageal echocardiography have become the standard of reference for evaluation of the thoracic aorta. Angiography is mainly performed as a presurgical procedure. Congenital pathologies observed during adulthood include coarctation, patent ductus arteriosus, and aberrant retroesophageal subclavian arteries. Imaging plays a major role for diagnosis and management of patients with acute aortic syndromes: intramural hematoma, dissection, penetrating ulcer and nondissecting aneurysms. Cross sectional imaging of the thoracic aortic wall allows evaluation of inflammatory diseases of the aorta or aortitis.

Familial aortic aneurysm in Leonberg dogs

A thoracic aortic aneurysm was diagnosed in a 6-month-old male Leonberg dog by use of radiography, transthoracic and transesophageal echocardiography, and magnetic resonance imaging. The aneurysm was associated with a twisted ascending aorta and dilatation of several other thoracic arteries (pulmonary trunk, brachiocephalic trunk, and left subclavian artery). Histologic examination of the aorta revealed cystic medial necrosis, with disruption of the elastic network, collagen fibers, and the muscle glycoprotein fibrillin-1. The dam and sire of the dog and 8 littermates were examined by use of transthoracic echocardiography. The sire and 1 male littermate also had an aneurysm of the ascending aorta. To the authors' knowledge, this is the first report of familial aortic aneurysm in dogs.

Overview of transesophageal echocardiography for the chest physician

Transesophageal echocardiography (TEE) is a growing technology that is frequently utilized in the critical care setting by intensivists, surgeons, anesthesiologists as well as specialists in cardiovascular diseases. The clinical application of TEE continues to emerge, and the indications and diagnostic utility of this technology as currently available are summarized in this review.

Acute aortic syndrome: a case presentation and review of the literature

Aortic disease can present as an acute chest pain syndrome. Although aortic dissection is the most common etiology, other processes such as intramural hematoma (IMH) and penetrating atherosclerotic ulcers are being increasingly recognized. They can all be accurately identified by computed tomography (CT) imaging or transesophageal echocardiography. The overlap between these processes regarding definition and mechanism is controversial. Treatment for all three conditions has thus far been dictated by location, wherein ascending or arch involvement (Stanford type A) necessitates surgery and descending disease (type B) is treated medically. Small studies suggest that subgroups of type A IMH may be treated medically with good outcomes.

New development of an ulcerlike projection in aortic intramural hematoma: CT evaluation

PURPOSE

To investigate the natural history and predictors of progression of a newly developed ulcerlike projection in patients with an aortic intramural hematoma.

MATERIALS AND METHODS

Serial computed tomographic (CT) findings in 52 patients with intramural hematoma were reviewed. Sixteen patients had Stanford type A intramural hematoma, and 36 had Stanford type B. Diagnosis of intramural hematoma was established with CT. Regular follow-up studies were performed every week during the 1st month and two or three times a year after the 2nd month. The presence or absence of an ulcerlike projection, diameter and progression of the projection, and aortic diameter were evaluated. Relationships among ulcerlike projections, clinical data, and CT findings were analyzed.

RESULTS

In 17 (33%) of the 52 patients, 17 ulcerlike projections were newly identified during the follow-up period. Patients with type A intramural hematoma had a significantly higher frequency of new development of ulcerlike projection than that of patients with type B intramural hematoma (P =.002). In 17 patients with new development of ulcerlike projection, 12 (70%) of 17 projections progressed to complications such as enlargement (n = 10) or progression to overt aortic dissection (n = 2). One of 10 enlarged projections progressed to rupture. A significant predictor of progression of ulcerlike projection was based on location from the ascending aorta to the aortic arch with the use of univariate (P =.009) and multivariate Cox (P =.018) regression analyses.

CONCLUSION

The location of ulcerlike projections is the principal predictor of progression, and careful follow-up study is needed for patients with an ulcerlike projection located from the ascending aorta to the aortic arch.

Clinical, diagnostic, and management perspectives of aortic dissection

The incidence of aortic dissection ranges from 5 to 30 cases per million people per year, depending on the prevalence of risk factors in the study population. Although the disease is uncommon, its outcome is frequently fatal, and many patients with aortic dissection die before presentation to the hospital or prior to diagnosis. While pain is the most common symptom of aortic dissection, more than one-third of patients may develop a myriad of symptoms secondary to the involvement of the organ systems. Physical findings may be absent or, if present, could be suggestive of a diverse range of other conditions. Keeping a high clinical index of suspicion is mandatory for the accurate and rapid diagnosis of aortic dissection. CT scanning, MRI, and transesophageal echocardiography are all fairly accurate modalities that are used to diagnose aortic dissection, but each is fraught with certain limitations. The choice of the diagnostic modality depends, to a great extent, on the availability and expertise at the given institution. The management of aortic dissection has consisted of aggressive antihypertensive treatment, when associated with systemic hypertension, and surgery. Recently, endovascular stent placement has been used for the treatment of aortic dissection in select patient populations, but the experience is limited. The technique could be an option for patients who are poor surgical candidates, or in whom the risk of complications is gravely high, especially so in the patients with distal dissections. The clinical, diagnostic, and management perspectives on aortic dissection and its variants, aortic intramural hematoma and atherosclerotic aortic ulcer, are reviewed.

Clinical significance of echo-free space detected by transesophageal echocardiography in patients with type B aortic intramural hematoma

To evaluate the prevalence and clinical significance of echo-free space (EFS) in aortic intramural hematoma (AIH) during transesophageal echocardiography (TEE), TEE performed during the acute phase in 71 consecutive patients with type B AIH was reviewed. Forty-four patients (62%) had EFS including 24 patients with a large EFS occupying >1/2 of the hematoma thickness. Among 59 patients who also underwent computed tomography, focal contrast enhancement in the hematoma area was observed in only 7 patients with a large EFS. Hospital mortality and incidence of surgical intervention in patients with EFS were 0% and 2%, respectively, which was similar to 4% in those without EFS. Follow-up imaging studies in 57 patients (80%) revealed development of typical aortic dissection (AD) in 6 patients and complete resorption of hematoma in 35; the incidence of either the development of AD or a complete resorption of hematoma was not significantly different between those with and without EFS. EFS by TEE is not rare in patients with type B AIH. It is not a poor prognostic factor and is not associated with the development of AD.

Penetrating atherosclerotic ulcer of the aorta

PURPOSE

To describe a case of penetrating atherosclerotic ulcer of the aorta with a review of its natural history, diagnosis and management.

CASE REPORT

An elderly patient with a history of hypertension presented to the emergency room with the sudden onset of severe chest pain radiating to the back. The electrocardiogram showed left ventricular hypertrophy; the chest radiograph revealed mediastinal widening. Computed tomography was suspicious for a mediastinal hematoma without aortic dissection. Transesophageal echocardiography was also negative for dissection. An aortogram revealed a penetrating atherosclerotic ulcer of the descending thoracic aorta. The patient underwent successful resection and repair of the lesion.

CONCLUSIONS

Penetrating atherosclerotic ulcer of the aorta is a potentially lethal lesion that must be promptly diagnosed and treated.

Transesophageal echocardiography in the diagnosis of diseases of the thoracic aorta: part II-atherosclerotic and traumatic diseases of the aorta

Transesophageal echocardiography (TEE) has provided an accurate new window for the evaluation of diseases of the thoracic aorta. Experience with TEE has led to an increased recognition of atherosclerosis of the thoracic aorta as a source of cerebral and systemic embolism. Certain features of aortic plaque morphology detected by TEE may prove to have prognostic and therapeutic significance. The intraoperative assessment of thoracic aortic atherosclerosis by TEE may guide modifications in surgical techniques and aortic manipulations that reduce the incidence of perioperative neurologic complications. TEE has also become a valuable tool for the diagnostic evaluation of patients with blunt chest trauma. The precise role of TEE in the management of these disorders is currently under investigation.