Echocardiography in the diagnosis of thoracic aortic pathology

Transthoracic two-dimensional and Doppler echocardiography has been well established as a useful technique for evaluating many pathologic processes affecting the thoracic aorta. However, the distance of the aortic arch and descending thoracic aorta from the chest wall and the interposition of highly attenuating lung and highly reflective mediastinal structures between the transducer and the aorta present unavoidable limitations. Transesophageal echocardiography is a relatively new technology that overcomes many of the inherent limitations with transthoracic imaging. Complete echocardiographic evaluation of the entire thoracic aorta can now be achieved in nearly all patients. This article will review the continually expanding role of echocardiography in the evaluation of thoracic aortic pathology, including the dramatic impact of transesophageal imaging on the diagnosis of life-threatening disorders such as aortic dissection.     

Aortic valve commissural tear mimicking type A aortic dissection.

A 52-year-old man came to the local emergency department with symptoms of heart failure and transient chest pain. Transthoracic echocardiography showed severe aortic regurgitation and a dilated ascending aorta. Aortic dissection was suspected, and he was transferred to our institution. Transesophageal echocardiography appeared to confirm the presence of a type A dissection. A mobile, linear structure was present in the proximal ascending aorta, suggesting the presence of dissection flap. Aortic cusp prolapse and severe aortic regurgitation were seen. At surgery, no aortic dissection was present. Rather, the commissure between right and left aortic valve cusps was separated from the wall of the aorta. Motion of the torn commissure with the cardiac cycle apparently led to the transesophageal echocardiographic appearance described. The ascending aorta was dilated. Histopathologic examination of the aorta confirmed the visual appearance of cystic medial necrosis. Aortic valve commissural tear is a rare event, which may lead to severe aortic regurgitation. This entity may lead to the false-positive transesophageal echocardiographic diagnosis of type A dissection.     

Comparison of conventional and transesophageal echocardiography with magnetic resonance imaging for anatomical mapping of thoracic aortic dissection

Thirty-five consecutive patients with clinically suspected aortic dissection were subjected to a dual noninvasive imaging protocol using comprehensive echocardiography and ECG-triggered MRI with multi-slice spin echo and cine sequences in random order. The purpose of this dual imaging study was to compare the diagnostic accuracy of two-dimensional and color-coded Doppler echocardiography using the conventional transthoracic (TTE) and the transesophageal approach (TEE) with magnetic resonance imaging (MRI) for the exact morphologic evaluation and anatomical mapping of the thoracic aorta. The results of each diagnostic method were validated independently against the ‘gold standard’ of intraoperative findings (n=17), necropsy (n=4) or contrast angiography (n=22). Compared to conventional transthoracic echocardiography both TEE and MRI were more reliable in detecting aortic dissections (TTE vs TEE: p<0.02; TTE vs MRI: p<0.01) and associated epiphenomena. Moreover, the reliability of TTE decreased significantly from proximal to distal segments of the aorta, e.g. from the ascending segment to the arch (p<0.05) and to the descending aorta (p<0.005), whereas the sensitivities of both TEE and MRI were excellent irrespective of the site of dissection. With regard to epiphenomena such as thrombus formation and entry location, MRI emerged as the optimal method for detailed morphologic information in all segments of the aorta. No serious side effects were encountered with either method. Thus, in patients with suspected acute or subacute aortic dissections the echocardiographic assessment should include the transesophageal approach for significant improvement of the moderate sensitivity and specificity of TTE. Both TEE and MRI are non-traumatic, safe and diagnostically accurate to identify and classify acute and subacute dissections of the thoracic aorta irrespective of their location. MRI provides superb anatomical mapping of all type A and B dissections and more detailed information on the site of entry and thrombus formation than TEE. These features of TEE and MRI may render retrograde contrast angiography obsolete in the setting of thoracic aortic dissection and may encourage surgical interventions exclusively on the basis of noninvasive imaging.     

Transesophageal echocardiography

Transesophageal echocardiography has provided a new acoustic window to the heart, the great vessels, and the mediastinum. It provides anatomical, functional hemodynamic, and blood flow information. High-quality visualization of left atrial appendage, thoracic aorta, atrial septum, and mitral valvular apparatus can be obtained readily. We discuss historical and technical aspects of transesophageal echocardiography, anatomical views, and major clinical indications for this procedure. These indications include intracardiac masses, thoracic aortic dissection, endocarditis, prosthetic and native cardiac valve function assessment, as well as its value in the detection of intracardiac source of systemic emboli. Furthermore, the role of transesophageal echocardiography in the assessment of coronary artery and congenital heart disease and as an intraoperative diagnostic and monitoring technique is discussed.     

Utility of transesophageal echocardiography for the characterization of cardiovascular anomalies associated with Turner's syndrome.

This case illustrates the complementary value of transesophageal echocardiography to routine transthoracic echocardiography in an asymptomatic adult patient with Turner's syndrome. The combined findings of bicuspid aortic valve, severe aortic dilation, coarctation of the aorta, and type A aortic dissection were clearly delineated by transesophageal echocardiography.     

Bicuspid aortic valve stenosis complicated by descending aortic dissection mimicking coarctation of the aorta.

We report a rare case of bicuspid aortic stenosis complicated by an ascending aortic aneurysm and aortic dissection of DeBakey type IIIb. A 35-year-old woman was admitted to our hospital to examine her systolic murmur identified at birth. Severe aortic stenosis, dilatation of the ascending aorta, and the narrow color flow signal in the descending aorta were detected by transthoracic echocardiography. Initially, coarctation of the descending aorta was suspected, but aortic dissection, DeBakey type IIIb, was revealed by transesophageal echocardiography. Transesophageal echocardiography is indicated when only insufficient information is available on valve and aortic morphology in patients with bicuspid aortic valve.     

Asymptomatic dissection of the ascending aorta: diagnosis by transesophageal echocardiography

A young man with marfanoid habitus underwent transesophageal echocardiography to evaluate an aortic root abnormality visualized on transthoracic echocardiography. Transesophageal echo demonstrated a type A aortic dissection traversing across the right sinus of Valsalva but not involving the aortic valve, right coronary artery, or pericardial sac. The aorta was not dilated. This is apparently the first reported case of an asymptomatic and uncomplicated aortic dissection localized to the sinus of Valsalva.     

经食管心脏超声对主动脉粥样硬化的研究

以经食管心脏超声技术在３５例患者和１０例离体主动脉检测了主动脉内膜－中层复合体最大厚度，同时计算了主动脉硬化指数。结果证明经食管心脏超声可清晰显示胸主动脉图像，并可作为评价主动脉解剖学病变及动脉粥样硬化的可靠措施在临床应用。     

Changes of aortic dimensions as evidence of cardiac pump mechanism during cardiopulmonary resuscitation in humans.

The mechanism of forward blood flow during cardiopulmonary resuscitation (CPR) remains controversial. We hypothesized that, if the heart acts as a pump, the proximal descending thoracic aorta would be distended during compression by forward blood flow, and would be constricted or remained unchanged if blood flow is generated by increased intrathoracic pressure. Fourteen patients with nontraumatic cardiac arrest underwent transesophageal echocardiography to verify changes in the descending thoracic aorta during standard manual CPR. The aortic dimensions, including cross-sectional area and diameter at the end of compression and relaxation, were measured proximal to, and at the maximal compression site of the descending thoracic aorta. At the maximal compression site, deformation of the descending thoracic aorta was observed during compression in all patients and the ratio of maximal to minimal diameter of the aorta (deformation ratio) decreased during compression compared with relaxation (0.58+/-0.15 vs. 0.81+/-0.11, P=0.001). This suggests eccentric compression of the descending thoracic aorta by external chest compression. The deformation ratio of the descending thoracic aorta proximal to the maximal compression site remained unchanged during compression and relaxation (1.0+/-0.88 vs. 1.0+/-0.9, P=0.345). The cross-sectional area of the descending thoracic aorta proximal to the maximal compression site increased 15% on average during compression compared with relaxation in 12 of 14 patients. In conclusion, deformation of the aorta at the maximal compression site and increase in the cross-sectional area of the proximal aorta suggests that cardiac pumping is the dominant mechanism in generating forward blood flow during CPR in humans.     

The technique of transesophageal echocardiography. How to procure detailed views of an array of cardiac structures

Use of transesophageal echocardiography (TEE) is growing in ambulatory, intensive care, and intraoperative settings. Forward flexion or retroflexion of the TEE probe tip at different levels in the esophagus reveals a variety of intracardiac structures; in the basal short-axis view, for example, the aortic valve can be seen, as can the left atrial appendage lateral to the aorta and pulmonary artery. In the four-chamber view, the mitral and tricuspid valves and interatrial septum can be viewed, and the morphology of the mitral valve leaflets and mitral annulus can be assessed. Cross-sectional views of both ventricles can be obtained in the transgastric short-axis view. In addition, the entire thoracic aorta, as well as the proximal ascending and transverse arch, can be visualized with TEE.     

Painless limited dissection of the ascending aorta presenting with aortic valve regurgitation

Aortic dissection is a medical emergency carrying high morbidity and mortality. Prompt diagnosis is sometimes difficult because of its varying presentations, but it is critical to the achievement of good clinical outcomes. This report describes 2 cases of painless aortic dissection that presented with aortic valve regurgitation. In both, the dissection was limited to the ascending aorta just distal to the aortic valve. These dissections were diagnosed by transthoracic and transesophageal echocardiography.     

Pitfalls in the diagnosis of thoracic aortic aneurysm by transesophageal echocardiography

A 74-year-old man underwent transesophageal echocardiography to evaluate the possibility of dissection of the descending aorta. The study demonstrated a round lumen that contained an echogenic mass mimicking aortic aneurysm with thrombus. However, computerized tomographic scanning identified the lumen as the pleural cavity containing a collapsed lung. The esophagus was on the right side of the spine, and the transesophageal technique could not visualize the descending aorta.     

主动脉缩窄合并右弓右降及多囊状动脉瘤的影像诊断

目的 研究主动脉缩窄合并右弓右降及多囊状动脉瘤的的影像学表现。方法 回顾性分析2例主动脉缩窄合并右弓右降及多囊状动脉瘤x线胸片、超声心动图、心血管造影、三维动态增强磁共振造影(3DDCEMRA)资料并与手术病理结果对照。结果 两例均为镜面右位主动脉弓(Ⅰ型)、主动脉缩窄、主动脉弓部多囊状动脉瘤。结论 心血管造影是诊断该类复杂畸形最可靠的方法，三维动态增强磁共振造影(3DDCEMRA)在一定程度上可以替代心血管造影，能为临床手术提供明确的定位与定性诊断。     

Transesophageal echocardiographic detection of thoracic aorta dissection extending into the celiac artery.

Special positioning of a transesophageal echocardiography probe allows visualization of the superior portion of the abdominal aorta including the celiac artery branch. This case report describes a thoracic aorta dissection that extended into the abdomen and involved the celiac artery.     

Using transesophageal echocardiography to manage critically ill patients. What role in hemodynamic instability, MI, embolic disease, trauma?

When transthoracic echocardiographic images are suboptimal, transesophageal echocardiography offers a new window for visualization of the heart and thoracic aorta. It can be performed at bedside in 15 to 20 minutes. Complications (emesis, hypoxemia, hypotension) are rare and easily reversed or averted by administration of naloxone or flumazenil. Indications include evaluation of hemodynamic instability, ventricular function, mitral regurgitation, ventricular septal defects, aneurysm, endocarditis, intracardiac sources of embolus, valve pathology, aortic dissection, intra-aortic debris, and trauma. Results can be analyzed immediately and used to guide further evaluation, medical therapy, or surgery.     

Headache as a manifestation of a life-threatening vascular disorder

Headache is a common complaint among patients seeking medical assistance. The differentiation between a primary headache disorder versus headache as a symptom of a serious underlying disease is of crucial importance. Dissections of the carotid or vertebral arteries frequently present with headache and can result in ischemic stroke. Rarely, headache or neck pain is a presenting symptom in patients with spontaneous proximal aortic dissection. We report on a 53-year-old man with a history of migraine with aura, who was admitted to the hospital because of severe frontal headache and neck pain. An anterior chest pain lasting for 10 minutes the day before and a diastolic heart murmur suggested a proximal aortic dissection, which was confirmed by transesophageal echocardiography. Patients with proximal aortic dissection rarely have headache or neck pain, reflecting the low incidence of carotid artery involvement in this disease. However, differentiation between an isolated cervical artery dissection and a proximal aortic dissection extending to the carotid arteries is pivotal, since treatment options are vastly different.     

The utility of multiple imaging modalities to diagnose acute aortic dissection

A 21-year-old man with Marfan syndrome and known aortic root aneurysm presented to our emergency department with symptoms suggestive of acute aortic dissection. The patient was hemodynamically stable and bilateral upper extremity blood pressures were similar. There was no mediastinal widening on portable chest radiograph. Both contrast CT and retrograde angiography of the aorta failed to identify dissection. Subsequent transesophageal echocardiography demonstrated a Stanford classification type A dissection. This case demonstrates the utility of multiple imaging modalities for identifying aortic dissection in high-risk patients.     

Prise en charge chirurgicale de la dissection aortique

Acute or chronic aortic dissections still represent a major challenge for the clinician. Despite its rarity, management is not easy, generally resulting in a bad short-term prognosis. Yet, recent studies based on the International registry of acute aortic dissection assessed clinical tools to help the clinician identifying the various presentations of aortic dissection. Emergency diagnosis relies on specific imaging including transesophageal echocardiography and computed tomography. Emergent surgical treatment is mandatory when the dissection involves the ascending aorta. Once the critical phase treated, the aortic dissection usually progresses to a chronic disease with aneurismal transformation and risks of tearing in the remaining dissected aorta, leading to significant mid- and long-term morbidity and mortality. Therefore patients previously treated for aortic dissection have to be tightly monitored during their whole life and rapidly reoperated if required.     

Review article: Accuracy of emergency physician performed point-of-care ultrasound of the thoracic aorta: A systematic review and narrative synthesis of the literature

Point-of-care ultrasound (POCUS) is becoming ubiquitous in emergency medicine. POCUS for abdominal aortic aneurysm is well established in practice. The thoracic aorta can also be assessed by POCUS for dissection and aneurysm and transthoracic echocardiography is endorsed by international guidelines as an initial test for thoracic aortic pathologies. A systematic search of Ovid Medline, PubMed, EMBASE, SCOPUS and Web of Science from January 2000 to August 2022 identified four studies evaluating diagnostic accuracy of emergency physician POCUS for thoracic aortic dissection (TAD) and five studies for thoracic aortic aneurysm (TAA). Study designs were heterogeneous including differing diagnostic criteria for aortic pathology. Convenience recruitment was frequent in prospective studies. Sensitivity and specificity ranges for studies of TAD were 41–91% and 94–100%, respectively when an intimal flap was seen. Sensitivity and specificity ranges for studies of thoracic aorta dilation >40 mm were 50–100% and 93–100%, respectively; for >45 mm ranges were 64–65% and 95–99%. Literature review identified that POCUS is specific for TAD and TAA. POCUS reduces the time to diagnosis of thoracic aortic pathology; however, it remains insensitive and cannot be recommended as a stand-alone rule-out test. We suggest that detection of thoracic aorta dilation >40 mm by POCUS at any site increases the suspicion of serious aortic pathology. Studies incorporating algorithmic use of POCUS, Aortic Dissection Detection Risk Score and D-dimer as decision tools are promising and may improve current ED practices. Further research is warranted in this rapidly evolving field.     

Usefulness of three-dimensional transesophageal echocardiography for diagnosis of hemolytic anemia due to inverted internal felt strip after surgery for aortic dissection

Felt strips are widely used for reinforcement of the aortic stump in surgery for aortic dissection (AD). Postoperative hemolytic anemia (HA) due to an inverted internal felt strip at the aortic stump fixation for AD is extremely rare. A 70-year-old woman underwent ascending aorta replacement for acute type A AD, where both proximal and distal anastomotic sites were reinforced with Teflon felt strips. A week later, macroscopic hematuria and HA emerged. Three-dimensional transesophageal echocardiography (3D-TEE) demonstrated that the proximal inner felt strip turned up and protruded into the aortic inner lumen. At redo surgery, which was performed 2 weeks after the initial surgery, the findings of 3D-TEE were confirmed, and the inverted internal felt strip was replaced with a bovine pericardial strip. The findings of HA disappeared immediately after the second surgery. 3D-TEE is a very informative, valuable modality for accurate diagnosis that leads to a safe surgery.