Two dimensional echocardiographic diagnosis of aortic dissection

Bedside-focused transthoracic echocardiography in acute atraumatic thoracic aortic syndrome: a systematic review and meta-analysis of diagnostic accuracy

The objective of this review is to assess the diagnostic accuracy of bedside-focused transthoracic echocardiography (TTE) in acute atraumatic thoracic aortic syndrome in adults. We performed a systematic review and meta-analysis of publications that described the use of bedside-focused TTE on adults presenting to the emergency care setting with suspected atraumatic thoracic aortic syndrome. Studies were identified using keyword and Medical Subject Heading searches on databases and grey literature, followed by abstract screening and study selection by two independent reviewers. Sixteen studies over six decades were included in the meta-analysis (n = 4569 patients). The prevalence of Type A thoracic aortic dissection was 11% (range 1.4-45.7%) and Type B dissection was 7% (range 1.8-30.55%). Type A dissection through direct visualisation of an intimal flap on TTE (i.e. direct sign) pooled sensitivity and specificity were 89% [95% confidence interval (CI), 82-94%] and 92% (95% CI, 88-95%) respectively. For Type B dissection, the pooled sensitivity was 65% (95% CI, 45-80%) and specificity was 100% (95% CI, 0.69-100%). TTE indirect signs for dissection showed a pooled sensitivity of 64% (95% CI, 5.2-98.2%) and specificity of 94% (95% CI, 92-96.1%) for aortic valve regurgitation, a pooled sensitivity of 92% (95% CI 54-99.2%) and specificity of 87% (95% CI, 62-97%) for thoracic aortic aneurysm and a pooled sensitivity of 39% (95% CI 33.8-45%) and a specificity of 94% (95% CI, 92-95%) for pericardial effusion. In this systematic review and meta-analysis, bedside-focused TTE has a good specificity for Type A and B dissection, but poor sensitivity for Type B, and unclear for intramural haematoma and penetrating aortic ulcer.

Echocardiography in the intensive care unit: An essential tool for diagnosis, monitoring and guiding clinical decision-making

In the last years, new trends on patient diagnosis for admission in cardiac intensive care unit (CICU) have been observed, shifting from acute myocardial infarction or acute heart failure to non-cardiac diseases such as sepsis, acute respiratory failure or acute kidney injury. Moreover, thanks to the advances in scientific knowledge and higher availability, there has been increasing use of positive pressure mechanical ventilation which has its implications on the heart. Therefore, there is a growing need for Cardiac intensivists to quickly, noninvasively and repeatedly evaluate various hemodynamic conditions and the response to therapy. Transthoracic critical care echocardiography (CCE) currently represents an essential tool in CICU, as it is used to evaluate biventricular function and complications following acute coronary syndromes, identify the mechanisms of circulatory failure, acute valvular pathologies, tailoring and titrating intravenous treatment or mechanical circulatory support. This could be completed with trans-esophageal echocardiography (TOE), advanced echocardiography and lung ultrasound to provide a thorough evaluation and monitoring of CICU patients. However, CCE could sometimes be challenging as the acquisition of good-quality images is limited by mechanical ventilation, suboptimal patient position or recent surgery with drains on the chest. Moreover, there are some technical caveats that one should bear in mind while performing CCE in order to optimize its use and avoid misleading findings. The aim of this review is to highlight the key role of CCE, providing an updated overview of its main applications and possible pitfalls in order to facilitate its use in CICU for clinical decision-making.

Association between delayed transthoracic echocardiography and in-hospital mortality in type A acute aortic dissection-associated ST-segment elevated myocardial infarction

Background

This study evaluates the association between transthoracic echocardiography (TTE) timing and in-hospital mortality among individuals presenting with ST-segment elevated myocardial infarction (STEMI) complicating type A acute aortic dissection (TAAAD).

Methods

This cohort study obtained the data of previously published case reports from searches of PubMed (1990–2020), and adults with STEMI secondary to TAAAD were finally included. Delayed TTE (dTTE) exposure was defined as when the TTE test was made available after antithrombotic management for STEMI due to an initially missed diagnosis of TAAAD. The primary outcome of interest was in-hospital mortality, comparing individuals with dTTE and those with emergency TTE (eTTE). The odds ratio (OR) with 95% confidence interval (CI) were calculated to provide an estimate of association.

Results

A total of 109 individuals with a mean age of 56.7 [standard deviation (SD) 12.9] years, and of whom 75 were men (68.8%) presenting with STEMI complicating TAAAD were included. Of all patients, 68 (62.4%) had a dTTE test, which tended to be associated with increased in-hospital mortality after adjustment (OR, 2.320; 95% CI, 0.743–7.248). The association between dTTE and in-hospital death was significant only among patients presenting with a high-risk examination (HRE) (OR, 11.196; 95% CI, 1.322–94.803) and with surgical therapy (OR, 5.375; 95% CI, 1.080–26.700), and not among those presenting with negative HRE (OR, 0.150; 95% CI, 0.016–1.397) and no surgical therapy (OR, 0.177; 95% CI, 0.008–4.018).

Conclusions

This study found an association between dTTE and increased in-hospital mortality in TAAAD-associated STEMI patients with surgical management. This association warrants further investigation.

Transient binocular blindness: A rare presentation of aortic dissection

Introduction:

Aortic dissection is a clinical chameleon that can have variable presenting features that require a careful history and physical examination. A non-specific presentation of this life-threatening condition causes a diagnostic dilemma among clinicians especially in the emergency department leading to grave consequences.

Case Presentation:

We present a case of aortic dissection that presented as an acute bilateral blindness that was associated with a sudden onset of loss of consciousness and central chest pain. Bedside carotid ultrasound showed a double lumen carotid artery suggesting an intraluminal flap. Computed tomography angiography revealed extensive dissection of the entire length of the aorta.

Discussion:

This case illustrated the need for a high index of suspicion to diagnose patients with aortic dissection especially as the patient presented with an acute binocular visual loss and chest pain.

Conclusion:

A bedside carotid artery ultrasound in the emergency department was found useful in screening and diagnosing a carotid artery–related pathology.

Takayasu's Arteriopathy with Associated Descending Thoracic Aortic Dissection During Pregnancy: A Multidisciplinary Approach Leading to a Successful Outcome: A Case Presentation

Takayasu's arteriopathy is a rare arterial inflammatory disease of unknown etiology that commonly affects the aorta, its major branches, and the pulmo nary artery. Although this process most often causes narrowing and occlusion of the vessels involved, it is associated only rarely with aneurysm formation or dissection of the vessel. Although there are sporadic reports of pregnancy in conjunction with Takayasu's arteriopathy, the combination of this disorder with pregnancy and an aortic dissection is very unusual.

This case report and literature review details the clinical management of a gravid female with clinical problems that were managed through close coopera tion among cardiothoracic surgery, anesthesia, obstetrics and gynecology, and perinatology units. This multidisciplinary approach led to the successful opera tive repair of a descending thoracic aortic dissection in a pregnant woman with Takayasu's arteriopathy who later delivered a normal full-term infant.

The role of transthoracic echocardiography in the diagnosis and management of acute type A aortic syndrome

BACKGROUND

Transthoracic echocardiography (TTE) has been traditionally considered inadequate for the diagnosis of acute type A aortic syndrome (AAAS). In the last decade, high-resolution probes and harmonic imaging have been implemented in new echocardiographic systems. However, studies assessing the diagnostic accuracy of TTE for the identification of AAAS in large populations using modern ultrasound technology are lacking.

METHODS

The diagnostic value of harmonic imaging TTE was assessed in 270 consecutive patients with suspected AAAS in whom TTE was the initial diagnostic test.

RESULTS

Acute type A aortic syndrome was diagnosed in 67 patients and excluded in 203 patients (disease prevalence 25%). Sixty-two patients had a classic acute type A aortic dissection, and 5, an acute type A intramural hematoma. Image quality achieved was considered optimal in 244 patients (90%). In the whole study population, TTE had sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of AAAS of 87%, 91%, 75%, and 95%, respectively. When evaluating only patients with optimal image quality, these values increased to 97%, 100%, 100%, and 99%, respectively. Forty-seven patients with clear-cut evidence of AAAS were transferred immediately to the operative room, where transesophageal echocardiography confirmed the diagnosis obtained by TTE in all patients.

CONCLUSIONS

Transthoracic echocardiography is a useful imaging modality for the diagnosis of classic acute type A aortic dissection. It cannot be used as the sole screening technique for detecting AAAS, but in the light of the predictive values observed, patients with optimal image quality and clear-cut diagnosis of AAAS should proceed to the operative room, whereas in patients with negative or indeterminate studies, other imaging techniques are needed to refine the diagnosis.

Bedside diagnosis of extensive aortic dissection

Acute aortic dissection (AAD) is a disease of relatively low incidence but very high mortality. Its presenting symptoms and signs are highly variable and frequently overlap with other less critical etiologies. The majority of patients expire prior to presentation to the Emergency Department. However, an even further complication is that nearly one-third of patients with AAD are misdiagnosed on initial evaluation. Standard imaging modalities for diagnosis of dissection include trans-esophageal echocardiography, CM and magnetic resonance imaging. All of these are expensive, time consuming and may not be readily available in a point of care setting. We present a case of an extensive AAD identified in a young patient with abdominal pain and neurological deficits. Point of care ultrasound allowed the identification of an intimal flap in multiple locations and resulted in rapid diagnosis and treatment.

Ultrasound diagnosis of type a aortic dissection

BACKGROUND

An aortic dissection is a life-threatening process that must be diagnosed and treated expeditiously. Imaging modalities used for diagnosis in the emergency department include computed tomography, magnetic resonance imaging, and trans-esophageal echocardiography. There are significant limitations to these studies, including patient contraindications (intravenous contrast dye allergies, renal insufficiency, metal-containing implants, hemodynamic instability) and the length of time required for study completion and interpretation by a radiologist or cardiologist.

OBJECTIVES

A case is presented that demonstrates how emergency physicians can use trans-thoracic and abdominal bedside ultrasound to diagnose a type A aortic dissection.

CASE REPORT

A 72-year-old woman presented with chest pain radiating to her neck and back that was concerning for aortic dissection. This was subsequently confirmed and further classified as a type A dissection by bedside emergency physician-performed ultrasound. The images showed a clear intimal flap in the abdominal aorta, a dilatated aortic root, and extension of the intimal flap into the left common carotid artery. With prompt diagnosis, the patient was able to have emergent surgical consultation, confirmatory imaging, and intervention before further complication occurred.

CONCLUSION

This case provides an example of how emergency trans-thoracic and abdominal ultrasound can be used to promptly diagnose a type A aortic dissection and expedite further consultation and prompt management.

The diagnosis of aortic dissection by emergency medicine ultrasound

A series of five cases of aortic dissection are presented that were diagnosed by emergency physicians using ultrasound to search the abdominal and thoracic aorta for pathology. Aortic dissection is a vascular emergency with a high morbidity and mortality, yet its presentation can be varied and subtle. This article reports the use of Emergency ultrasound in a series of five aortic dissections discovered with a limited, yet timely viewing of the aorta and heart by emergency physicians.

Acute aortic syndromes: aortic dissections, penetrating aortic ulcers and intramural aortic hematomas

Acute aortic syndromes, including dissections, intramural hematomas and penetrating aortic ulcers, are a catastrophic clinical entity that are relatively uncommon. A high index of clinical suspicion along with proper imaging modalities are critical in making a prompt and accurate diagnosis for immediate management and to improve survival of the patient.

Live three-dimensional transthoracic echocardiographic assessment of aortic dissection

In the present study, we report our experience of using live three-dimensional transthoracic echocardiography in the assessment of aortic dissection in ten adult patients. To our knowledge, this has not been reported previously.

Acute atypical type-A thoracic aortic dissection with intramural hematoma: the importance of patient symptoms and the transthoracic echocardiographic examination

This report demonstrates how transthoracic echocardiography, in conjunction with the sonographer's attention to patient symptomatology, heightened the clinical suspicion of an atypical aortic dissection, leading to further investigation and confirmation. Although initially undiagnosed by computed tomography, a structure suggestive of aortic dissection was subsequently found by transthoracic echocardiography. Transesophageal echocardiography and a second computed tomography examination validated the transthoracic findings. An atypical type A aortic dissection with intramural hematoma was confirmed at operation.

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.

Dissection of the proximal thoracic aorta: a new ultrasonographic sign in the subxiphoid view

Dissection of the thoracic aorta is a life-threatening event that presents with some regularity to emergency departments (EDs). Despite often nonspecific symptoms, it is critical to catch this disease process early, especially when the proximal aorta is involved because dissections involving the aortic root can lead to myocardial infarction and failure of the aortic valve resulting in death. Current imaging options include contrast-enhanced chest computed tomography (CT), angiography, magnetic resonance imaging, or transesophageal echocardiography. Although not as accurate as transesophageal echocardiography, transthoracic echocardiography (TTE) can be used to detect aortic dissection as well. We present a previously undescribed echocardiographic finding associated with proximal dissection of the thoracic aorta in 7 cases.

Determinants of aortic artifacts during transesophageal echocardiography of the ascending aorta

BACKGROUND

The origin of artifacts of the ascending aorta during transesophageal echocardiography has not been widely studied. This study was undertaken to investigate in vivo whether anatomic features could determine the appearance of artifacts.

METHODS AND RESULTS

Transesophageal echocardiograms of 46 patients studied for suspected dissection with proven diagnosis (30 patients with and 16 without ascending aortic dissection) were reviewed. The incidence of artifacts was 46%, and it was similar in patients with and those without dissection (chi-square 0.516; P = not significant). Artifacts were located in the aortic lumen twice as far from the transducer as the atrial-aortic interface. The aortic diameter was larger in patients with than in those without artifacts (6.4 +/- 1.1 vs 4.2 +/- 0.9 cm, P <.001). An aortic diameter >5 cm and an atrial-aortic ratio </=0.6 predicted the artifact appearance with good sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy; these parameters reached a value of 100% by analysis only of patients without dissection.

CONCLUSIONS

An ascending aortic diameter >5.0 cm that exceeds the left atrial diameter with an atrial-aortic ratio </=0.6 creates in vivo the conditions for the reverberation of the atrial-aortic interface within the aorta. Therefore, in patients with such anatomic features, artifacts must be suspected in the presence of linear structures within the aorta.

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.

Clinical and echocardiographic findings in patients with suspected acute aortic dissection

OBJECTIVES

The objective of this study was to define the range of clinical presentations, echocardiographic findings, and underlying final diagnoses in patients with clinically suspected acute aortic dissection.

METHODS AND RESULTS

This study was designed as a retrospective review of clinical and echocardiographic data in consecutive patients evaluated for clinically suspected acute aortic dissection. The study population consisted of 75 studies in 74 consecutive patients referred for urgent or emergency evaluation because of signs and symptoms suggesting acute aortic dissection. A history and physical examination designed to elicit the cause of chest pain, evidence of congestive heart failure, and other cardiovascular abnormalities was performed in each patient. All patients underwent transesophageal echocardiography by experienced operators. Routine 12-lead electrocardiograms and chest radiographs were available for review in the majority of patients. Magnetic resonance imaging or computed tomography was performed in only 5 (6%) and 34 (44%) patients, respectively. Contrast aortography was performed in 21 (27%) patients. For the entire patient cohort, the most prevalent symptom was chest pain alone (n = 31; 41%) or chest pain in conjunction with back pain (n = 23; 31%). Classic "tearing" pain was an infrequent symptom. Syncope or other neurologic findings were present in 15 (20%) patients. Acute aortic dissection was responsible for 34 (45%) of the 75 presentations, with 31 (41% of total evaluations, 92% of dissections) involving the ascending aorta (Stanford type A, DeBakey type 1 or 2). Alternate major cardiovascular diagnoses, including acute myocardial infarction, primary valvular disease, or pericardial disease, were established in 12 (16%) cases. Aortic pathology, other than dissection, was found in 15 (20%) cases. Transesophageal echocardiography established the diagnosis responsible for the symptoms in 61 (81%) cases.

CONCLUSIONS

Symptoms in patients with acute aortic dissection are more variable than commonly recognized. Transesophageal echocardiography is an accurate primary diagnostic tool in patients with clinically suspected acute aortic dissection. It allows rapid diagnosis of dissection and can identify alternate cardiovascular pathology responsible for the symptoms in a significant number of patients without acute dissection.

Clinical and echocardiographic outcomes of aortic intramural hemorrhage compared with acute aortic dissection

Aortic intramural hemorrhage (IMH), which presents clinical manifestations identical to those of acute aortic dissection, is different from aortic dissection in terms of the absence of intimal tear and communication of blood flow between the true and false lumen. This study was conducted for the purpose of diagnosing IMH by transesophageal echocardiography (TEE) prospectively and comparing the clinical and echocardiographic outcome of IMH with aortic dissection. Between August 1991 and November 1996, 27 IMHs and 73 acute aortic dissections were diagnosed using TEE in 202 consecutive patients with suspected aortic dissections. The TEE diagnoses of IMH and aortic dissection were initially compared with computed tomography and magnetic resonance imaging and later confirmed by operative findings (n = 37) or follow-up changes (n = 12). In the 49 patients whose diagnosis was confirmed by operation or follow-up changes, the sensitivity and specificity of TEE for the diagnosis of IMH were 27 of 27 (100%) and 20 of 22 (91%), respectively. There were 11 deaths in 73 patients (15%) from acute aortic dissection and 1 death in 27 patients (4%) from IMH during a follow-up of 1.7+/-1.5 years (p = NS). Stanford classification and types of treatment were not related to death in both groups. Complications developed less often in patients with IMH (3 of 27) than in those with acute aortic dissection (24 of 73), and no death occurred in patients with uncomplicated IMH who were medically treated. A follow-up imaging study of 12 IMH patients showed complete resolution in 8, regression in 3, and progression in 1 patient. TEE is accurate in the diagnosis of IMH and IMH has a lower incidence of complications than aortic dissection because of the absence of intimal tear and communication of blood flow in the false lumen.

Surgical repair of type-A aortic dissection: early and late results in 32 consecutive patients

BACKGROUND

Acute type-A aortic dissection is a surgical emergency. One unit's experience in the surgical repair of type-A aortic dissection is documented.

METHODS

Surgical treatment was undertaken for type-A aortic dissection in 32 consecutive patients between January 1988 and August 1994 at Royal North Shore Hospital. Retrosternal chest pain was the commonest presenting symptom and in four of these cases it was initially misinterpreted as myocardial ischaemia.

RESULTS

A total of 24 patients had signs of aortic incompetence on presentation. Computed tomography (CT) scanning was the commonest modality of definitive diagnosis, but trans-oesophageal echocardiography was used as confirmation wherever possible, and we now consider it the initial, best investigation whenever a diagnosis of dissection is considered. There were 15 supra-coronary ascending aortic replacements, and a further four with aortic valve re-suspension. There were 13 operations of the Bentall's type. The overall 30-day mortality was 19%. The late mortality was 19%, with 62% long-term survival at a mean follow-up of 4.8 years.

CONCLUSION

Early diagnosis and surgical intervention can give excellent palliation and improved life expectancy in acute type-A aortic dissection.

The aorta. Aortic aneurysm, trauma, and dissection

Because of the close relationship between the esophagus and the aorta, multiplane transesophageal echocardiography provides an excellent way to view the thoracic aorta. In this article, clinical features of aortic aneurysm, trauma, and aortic dissection are described, as is the potential use of transesophageal echocardiography in the assessment of these entities.

Diagnosis of ascending aortic dissection by transesophageal echocardiography: utility of M-mode in recognizing artifacts

OBJECTIVES

This study sought to assess the reliability of biplanar transesophageal echocardiography in the diagnosis of ascending aortic dissection and to test the utility of M-mode information in the differential diagnosis of ascending aortic ultrasound artifacts and intimal flap images.

BACKGROUND

Transesophageal echocardiography is a useful technique in the diagnosis of aortic dissection. However, ultrasound artifacts in the ascending aorta are an important limitation.

METHODS

Transesophageal echocardiography was performed in 132 consecutive patients with clinically suspected aortic dissection. Two-dimensional and M-mode echocardiography and color Doppler were used to diagnose intimal flap and artifact images. Diagnoses were validated either anatomically or with reference techniques.

RESULTS

The sensitivity and specificity of transesophageal echocardiography in the diagnosis of ascending aortic dissection were 96.8% and 100%, respectively. Ninety-three artifacts were observed in 56 (55%) of 101 patients without ascending aortic dissection. Two-dimensional echocardiography easily identified 74 artifacts (80%). Color Doppler showed no ascending flow abnormalities in 71% of artifact images. M-mode echocardiography showed three location and mobility artifact patterns related to the posterior wall of the aorta or the right pulmonary artery. In contrast, intimal flap movement showed no relation to the aortic wall movement in 25 cases (83%). Blind analysis of transesophageal echocardiographic study tapes underlined the utility of M-mode in the differential diagnosis. Ranges of sensitivity, specificity and positive predictive value (established by including doubtful results as either positive or negative) improved from 87.1-93.5% to 93.5-96.8%, from 85.1-94.1% to 99-100% and from 65.9-81.8% to 96.8-100%, respectively, with the inclusion of M-mode data.

CONCLUSIONS

Biplanar transesophageal echocardiography permits reliable diagnosis of ascending aortic dissection. Ultrasound artifacts are common, but assessment of the location and mobility of intraluminal images by M-mode echocardiography definitely improves diagnostic accuracy.

Feasibility, accuracy and safety of magnetic resonance imaging in acute aortic dissection

Magnetic resonance imaging (MRI) is the most accurate method of defining the morphology and haemodynamic features of thoracic aortic dissection. However, because of doubts about its safety in acute situations, its use has so far been confined to imaging chronic dissections. We present a prospective study of 50 patients thought clinically to have acute thoracic aortic dissection in which a rapid diagnosis was made by MRI.

Comparative diagnostic value of transesophageal echocardiography and retrograde aortography in the evaluation of thoracic aortic dissection

The aim of this study was to assess the comparative diagnostic value of transesophageal echocardiography (TEE) and retrograde aortography for morphologic evaluation and anatomic mapping of aortic dissection. Seventy patients (aged 18 to 79 years) were prospectively evaluated with both techniques for suspected aortic dissection. In 64 patients, findings on aortography and TEE could be validated against intraoperative (n = 53) and postmortem (n = 11) findings. Examination time was significantly shorter for TEE (9 +/- 6 vs 48 +/- 25 minutes; p < 0.001). For the detection of aortic dissection, aortography showed lower sensitivity (87.5% vs 97.5%) and negative predictive value (85.3% vs 96.7%; both trends did not reach statistical significance) due mostly to the inability to identify noncommunicating dissection (dissection without intimal tears). For the epiphenomena of aortic dissection, aortography was significantly more accurate (97.2% vs 78%; p < 0.05) in assessing the site of entry, and TEE was more accurate in identifying thrombus formation (90% vs 65%; p < 0.05). There was no significant difference between aortography and TEE with regard to assessing secondary tears, aortic regurgitation, coronary dissection, and extension of the dissection. Thus, both TEE and aortography offer detailed anatomic mapping for guided surgical interventions. In elective patients, integration of both techniques seems the best approach; in unstable patients, TEE may be preferential because it is less invasive, requires no contrast injection, and provides accurate diagnosis in a short time at the bedside.

Comparison of conventional and transesophageal echocardiography with magnetic resonance imaging for anatomical mapping of thoracic aortic dissection. A dual noninvasive imaging study with anatomical and/or angiographic validation

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.

Aorta: comprehensive evaluation by echocardiography and transesophageal echocardiography

The emergence of transesophageal echocardiography has made echocardiography a nearly ideal technique for evaluating the thoracic aorta. The echocardiographic anatomy of the aorta is reviewed. The role of echocardiography for evaluating aortic dissection, thoracic aortic aneurysm, aortic atherosclerosis, and thoracic aortic trauma is discussed. Comparison of echocardiography with other techniques for imaging the aorta (computed tomographic scan, nuclear magnetic resonance, and aortography) is presented.

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.

The diagnosis of thoracic aortic dissection by noninvasive imaging procedures

BACKGROUND AND METHODS

This study was designed to assess the safety and reliability of new noninvasive imaging methods as compared with aortography in the diagnosis of dissection of the thoracic aorta. One hundred ten patients with clinically suspected aortic dissection followed a diagnostic protocol that included transthoracic and transesophageal color-flow Doppler echocardiography (TTE and TEE), contrast-enhanced x-ray computed tomography (CT), and magnetic resonance imaging (MRI). Imaging results were compared in a blinded fashion and validated independently against intraoperative findings in 62 patients, autopsy findings in 7, and the results of contrast angiography in 64.

RESULTS

The sensitivities of MRI, TEE and x-ray CT for detecting dissection were similar, at 98.3, 97.7, and 98.3 percent, respectively; TTE had a sensitivity of only 59.3 percent (P < 0.005). The specificities of both TTE (83.0 percent) and TEE (76.9 percent) were lower than those of x-ray CT (87.1 percent) and MRI (97.8 percent; P < 0.05), mainly as a result of false positive findings in the ascending aorta. MRI and x-ray CT were more sensitive than TTE in detecting the formation of thrombus in the entire thoracic aorta (P < 0.05), but were not superior to TEE in this regard. CT was not effective in detecting an entry site or aortic regurgitation, but MRI and TEE accurately identified both. Two patients died during or soon after CT and TEE, and three died between retrograde angiography and surgery.

CONCLUSIONS

A noninvasive diagnostic strategy using MRI in all hemodynamically stable patients and TEE in patients who are too unstable to be moved should be considered the optimal approach to detecting dissection of the thoracic aorta. Comprehensive and detailed evaluation can thus be reduced to a single noninvasive diagnostic test in the investigation of suspected dissection of the thoracic aorta.

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.

Diagnosis of thoracic aortic dissection. Magnetic resonance imaging versus transesophageal echocardiography

BACKGROUND

Aortic dissection requires prompt and reliable diagnosis to reduce the high mortality. The purpose of this study was to assess the reliability of both ECG-triggered magnetic resonance imaging (MRI) and transesophageal two-dimensional echocardiography combined with color-coded Doppler flow imaging (TEE) for the diagnosis of thoracic aortic dissection and associated epiphenomena.

METHODS AND RESULTS

Fifty-three consecutive patients with clinically suspected aortic dissection were subjected to a dual noninvasive imaging protocol in random order; imaging results were compared and validated against the independent morphological "gold standard" of intraoperative findings (n = 27), necropsy (n = 7), and/or contrast angiography (n = 53). No serious side effects were encountered with either imaging method. In contrast to a precursory screening transthoracic echogram, the sensitivities of both MRI and TEE were 100% for detecting a dissection of the thoracic aorta irrespective of its location. The specificity of TEE, however, was lower than the specificity of MRI for a dissection (TEE, 68.2% versus MRI, 100%; p less than 0.005), which resulted mainly from false-positive TEE findings confined to the ascending segment of the aorta (TEE, 78.8% versus MRI, 100%; p less than 0.01). In addition, MRI proved to be more sensitive than TEE in detecting the formation of thrombus in the false lumen of both the aortic arch (p less than 0.01) and the descending segment of the aorta (p less than 0.05). There were no discrepancies between the two imaging techniques in detecting the site of entry to a dissection, aortic regurgitation, or pericardial effusion.

CONCLUSIONS

Both MRI and TEE are atraumatic, safe, and highly sensitive methods to identify and classify acute and subacute dissections of the entire thoracic aorta. TEE, however, is associated with lower specificity for lesions in the ascending aorta. These results may still favor TEE as a semi-invasive diagnostic procedure after a precursory screening transthoracic echogram in suspected aortic dissection, but they establish MRI as an excellent method to avoid false-positive findings. Anatomic mapping by MRI may emerge as the most comprehensive approach and morphological standard to guide surgical interventions.

Diagnosis of acute thoracic aortic dissection using combined echocardiography and computed tomography

Acute dissection of the thoracic aorta is a life-threatening emergency requiring a diagnosis which is rapid, accurate and safe, and which will distinguish between dissections involving the ascending and descending aorta. In the absence of any general agreement on the best method of making this diagnosis we studied the use of combined echocardiography and contrast-enhanced computed tomography (CT) to diagnose acute aortic dissection. Over a 3 year period 23 patients were investigated in this way. Aortic dissection was demonstrated in 18 cases, involving the ascending aorta in 15, and the descending aorta alone in three. The diagnosis of aortic dissection was confirmed in 13 patients at surgery, in one at aortography and in one at autopsy. Three patients died without surgery or autopsy being performed to confirm the diagnosis and the subsequently which accounted for their symptoms. This combined approach has proved a valuable and safe means of investigating aortic dissection.

Impact of transesophageal echocardiography on the treatment of patients with aortic dissection

To determine the impact of transesophageal echocardiography (TE) on the treatment of patients with aortic dissection, the clinical course and outcome of 18 patients with TE diagnosis of dissection were analyzed. Ascending aortic dissection was present in nine patients, of whom six had surgery with confirmation of TE findings. Angiography was performed in only two of these patients and was falsely negative in one patient. Angiography was not performed in the three patients who were not surgical candidates. In the nine patients who had descending aortic dissection, angiography was performed in seven patients, of whom two underwent surgery. Information provided by angiography did not change the treatment of these patients. Thus, TE provides a prompt and accurate diagnosis in aortic dissection obviating the need for angiography in most patients.

Usefulness of transesophageal echocardiography in assessment of aortic dissection

BACKGROUND

The value of transesophageal echocardiography in the assessment of patients with aortic dissection was studied.

METHODS AND RESULTS

Group 1 (34 patients) represented all patients studied at our institution with this technique in whom aortic dissection was proven by aortography, surgery, or autopsy. Group 2 (27 patients) represented all patients studied with this technique at our institution in whom aortic dissection was excluded by aortography. Transesophageal echocardiography made a correct diagnosis of aortic dissection in 33 of 34 patients (sensitivity, 97%; specificity, 100%). It also correctly demonstrated the type of dissection in all 29 patients with aortographic or surgical proof. On the other hand, computed tomography scanning, performed in 24 of 34 patients in group 1, made a correct diagnosis in only 67% of patients and misclassified the type of dissection in 33%. Transesophageal echocardiography correctly identified involvement of the coronary arteries by aortic dissection in six of seven patients as well as absence of both left and right coronary artery involvement in 10 patients with aortic dissection. This technique was also useful in detecting communications between the true and false lumens, presence of thrombi in the false lumen, and, in two patients, localized dissection rupture with formation of a false aneurysm. In both groups 1 and 2, transesophageal echocardiography correctly identified patients with moderate to severe aortic regurgitation.

CONCLUSIONS

Transesophageal echocardiography is very useful in the assessment of aortic dissection.

The evaluation of the abdominal aorta: a "how-to" for cardiac sonographers

A thorough evaluation of the abdominal aorta can be readily achieved by use of the standard views of the echocardiographic examination. The ultrasound evaluation of the abdominal aorta represents a logical extension of the standard echocardiographic examination of the adult patient. This article provides the information needed to carry out a complete ultrasound examination of the abdominal aorta including the anatomy, the vascular disease, and the steps involved in accomplishing the ultrasound examination of the abdominal aorta.

Aortic dissection and rupture that produce right ventricular perforation: detection by echocardiography and color flow mapping

Aorta to right ventricular fistula is a rare complication of ascending aortic dissection that has previously been diagnosed ante mortem only by cardiac catheterization. This report describes a patient who had aorta to right ventricular fistula that caused a left-to-right shunt and marked hemodynamic instability. An anatomic diagnosis was made rapidly in this patient by use of echocardiographic techniques. Two-dimensional and Doppler echocardiography have an important role in defining the cause of cardiovascular collapse after aortic dissection.

Assessment of transesophageal Doppler echography in dissecting aortic aneurysm

To assess the clinical value of transesophageal Doppler echography in the diagnosis of dissecting aortic aneurysm, both transesophageal and conventional echograms were performed in 22 cases of dissecting aortic aneurysm. Of the 22 patients, 17 underwent angiography; 8, X-ray computed tomography; 4, both; and 12, surgery. The performance of each method was assessed in the following four segments: A, ascending aorta; B, aortic arch; C, thoracic descending aorta; and D, upper abdominal aorta. The results by angiography were presumed to be correct. In the group of 17 patients who underwent angiography, the rate of correct detection of an intimal flap using the transesophageal approach was 100% in all four segments, significantly better than detection by the conventional approach (segment A, 65%; segment B, 47%; segment C, 35%; segment D, 53%) (p less than 0.01), and the rate of correct detection of the entry sites using the transesophageal approach was 100%, significantly better than that by conventional approach (42%) (p less than 0.05). X-ray computed tomography was not capable of detecting the site of entry in all cases. The presence of thrombus, aortic regurgitation and pericardial hemorrhage were all revealed clearly by the transesophageal approach, and the results were partly proved by other methods. In conclusion, transesophageal Doppler echography provides a rapid and accurate method of diagnosing and evaluating dissecting aortic aneurysm and permits prompt initiation of appropriate treatment.

Echocardiography in diagnosis of aortic dissection

In a multicentre study the accuracy of echocardiography was measured in 164 consecutive patients with suspected aortic dissection. The diagnosis was subsequently proven (82 patients) on the basis of transthoracic and transoesophageal echocardiography and additional diagnostic procedures, including computed tomography (CT), aortic angiography, and surgery and/or necropsy. The sensitivity and specificity of echocardiography were 99% and 98%, respectively, with positive and negative predictive values of 98% and 99%. For CT sensitivity was 83%, specificity 100%, and positive and negative predictive values 100% and 86%, respectively. For aortography sensitivity and specificity were 88% and 94%, and the positive and negative predictive values 96% and 84%, respectively. Echocardiography, including the transoesophageal route, can provide accurate diagnosis of aortic dissection within 15 min. Diagnostic difficulties occur only in a few type II dissections, when complementary diagnostic procedures, including CT or angiography, may be needed. To clarify branch involvement angiography is required.

Utility of echocardiography in the diagnosis of aortic dissection involving the ascending aorta

We report our prospective experience with sensitivity, specificity, predictive values and efficiency of echocardiography in diagnosing AD involving the ascending aorta (type A). We studied two groups of patients with both echocardiography and aortography. Group 1 was made up by 46 consecutive patients with clinical suspicion of AD. Type A AD was confirmed in 23 cases. Group 2 was comprised of 509 adult patients who had been studied during the same period with both aortography and echocardiography (including 46 patients from group 1); prevalence of type A AD in this group was 4.9 percent. We conclude that the diagnostic usefulness of echocardiography in patients with suspected type A AD is limited by its moderate sensitivity and predictive positive value. Aortography remains the major step in diagnosis. Within these limitations, echocardiography is useful in confirmation of clinical suspicion if all three main echocardiographic signs are present (predictive positive value: 100 percent).