Diagnostic accuracy of transesophageal echocardiography, helical computed tomography, and magnetic resonance imaging for suspected thoracic aortic dissection: systematic review and meta-analysis

BACKGROUND: Patients with suspected thoracic aortic dissection require early and accurate diagnosis. Aortography has been replaced by less invasive imaging techniques including transesophageal echocardiography (TEE), helical computed tomography (CT), and magnetic resonance imaging (MRI); however, accuracies have varied from trial to trial, and which imaging technique should be applied to which risk population remains unclear. We systematically reviewed the diagnostic accuracy of these imaging techniques in patients with suspected thoracic aortic dissection. METHODS: Published English-language reports on the diagnosis of thoracic aortic dissection by TEE, helical CT, or MRI were identified from electronic databases. Sensitivity, specificity, and positive and negative likelihood ratios were pooled in a random-effects model. RESULTS: Sixteen studies involving a total of 1139 patients were selected. Pooled sensitivity (98%-100%) and specificity (95%-98%) were comparable between imaging techniques. The pooled positive likelihood ratio appeared to be higher for MRI (positive likelihood ratio, 25.3; 95% confidence interval, 11.1-57.1) than for TEE (14.1; 6.0-33.2) or helical CT (13.9; 4.2-46.0). If a patient had shown a 50% pretest probability of thoracic aortic dissection (high risk), he or she had a 93% to 96% posttest probability of thoracic aortic dissection following a positive result of each imaging test. If a patient had a 5% pretest probability of thoracic aortic dissection (low risk), he or she had a 0.1% to 0.3% posttest probability of thoracic aortic dissection following a negative result of each imaging test. CONCLUSION: All 3 imaging techniques, ie, TEE, helical CT, and MRI, yield clinically equally reliable diagnostic values for confirming or ruling out thoracic aortic dissection.     

Optimal management of acute aortic dissection

Opinion statement  Acute aortic syndrome (AAS) encompasses a group of life-threatening aortic disorders that are increasing in prevalence. It classically presents with abrupt-onset chest pain that is of maximum intensity at onset. The syndrome requires prompt recognition and efficient treatment to optimize outcome. Contrast-enhanced CT is most commonly used as the definitive diagnostic imaging modality. Patients must be expeditiously transferred to institutions with case experience and medical, surgical, and endovascular expertise. Stanford type A dissections involve the ascending aorta and require emergent surgical consideration, unless underlying comorbidities make surgical risk prohibitive. Patients with Stanford type B, or descending, aortic dissection are less prone to rupture, shock, and cardiac complications. These patients are initially medically managed with targeted blood pressure and heart rate control. Surgical management is reserved for patients with intractable or recurrent pain, aortic expansion, end-organ ischemia, or progression of dissection. The feasibility of endovascular treatment is established, and its role in management continues to expand. Long-term follow-up with medical treatment and serial imaging of AAS patients is critical. Future directions in the diagnosis and treatment of AAS include using biomarkers to aid in diagnosis and prognosis, enhanced imaging with better resolution and reduced radiation exposure, and definition of the role of endovascular methods in acute and chronic settings.     

Biomarkers in acute aortic dissection and other aortic syndromes

Acute aortic syndromes have an incidence of >30 per million per annum and a high mortality without definitive treatment. Survival may relate to the speed of diagnosis. Although pain is the most common symptom, there is a large fraction of patients in whom the diagnosis may be mistaken or overlooked. Currently, a high index of clinical suspicion is the chief prompt that diverts a patient into a definitive algorithm of imaging investigations. Although there is no point-of-care biochemical test that can be reliably used to positively identify dissection, biomarkers are available that could accelerate the diagnostic pathway and thereby expedite treatment.     

Screening, Evaluation, and Early Management of Acute Aortic Dissection in the ED

Acute aortic dissection (AAD) is a rare and lethal disease with presenting signs and symptoms that can often be seen with other high risk conditions; diagnosis is therefore often delayed or missed. Pain is present in up to 90% of cases and is typically severe at onset. Many patients present with acute on chronic hypertension, but hypotension is an ominous sign, often reflecting hemorrhage or cardiac tamponade. The chest x-ray can be normal in 10-20% of patients with AAD, and though transthoracic echocardiography is useful if suggestive findings are seen, and should be used to identify pericardial effusion, TTE cannot be used to exclude AAD. Transesophageal echocardiography, however, reliably confirms or excludes the diagnosis, where such equipment and expertise is available. CT scan with IV contrast is the most common imaging modality used to diagnose and classify AAD, and MRI can be used in patients in whom the use of CT or IV contrast is undesirable. Recent specialty guidelines have helped define high-risk features and a diagnostic pathway that can be used the emergency department setting. Initial management of diagnosed or highly suspected acute aortic dissection focuses on pain control, heart rate and then blood pressure management, and immediate surgical consultation.     

Current role of conventional and digital aortography in the diagnosis of aortic disease

The availability of the less invasive techniques such as CT, MRI, and digital angiography require reexamination of the indications for conventional screen-film aortography. Because of poor image quality, IV digital subtraction angiography should be limited to congenital aortic disease and follow-up cases. Intraarterial digital angiography can be used as a supplement to or as a replacement for conventional aortography in most cases. Care should be used in substituting intraarterial digital angiography for conventional studies in aortic dissection and aortic rupture; continuing problems with digital subtraction artifacts may introduce error in cases with subtle abnormalities. In aortic aneurysm, CT is usually sufficient for diagnosis and surgical planning with angiography used for inconclusive examinations or more accurate determination of branch involvement. CT is the primary diagnostic examination in suspected chronic or subacute dissection and is the method of choice in sequential studies of patients following medical or surgical therapy for dissection. In acute aortic dissection, either angiography or CT may be used and are equally diagnostic. Angiography is most helpful in aortic dissection with suspected brachiocephalic vessel involvement, coexistant coronary artery disease, or in cases of indeterminate CT. In blunt chest trauma, aortography remains the examination of choice in the diagnosis of aortic transection. CT may play a role in excluding aortic damage in stable patients with a low clinical suspicion of aortic transection.     

„Standard operating procedures“ zur Diagnostik und Therapie des akuten Aortensyndroms

Acute aortic syndrome (AAS) describes a life threatening condition. Mortality rates in the initial phase remain high. Early diagnosis and therapy are essential to improving prognosis in these patients. Based on an advanced event-driven process chain (EPC) which addresses the diagnostic process as well as the therapy strategies for patients with AAS, standard operating procedures (SOPs) were developed. An estimation of pre-test risk of thoracic aortic dissection (AoD) is done by determination of risk factors that are associated with an AoD. Expedited aortic imaging is recommended to identify or exclude AoD in patients at high risk for the disease. For patients in the non-high risk group further diagnostic evaluation is necessary. In these patients a second risk-evaluation is done to indicate the need for urgent aortic imaging. After the diagnosis of an AoD could be made therapeutic strategies are based on the Stanford classification. AoD involving the ascending aorta (Stanford A) should be urgently evaluated for emergent surgical repair whereas AoD involving the descending aorta (Stanford B) should be managed medically unless life-threatening complications develop.     

Aortic dissection in children and young adults: diagnosis, patients at risk, and outcomes

OBJECTIVE: To heighten the awareness of pediatricians and pediatric cardiologists to aortic dissection, a potentially dangerous medical condition. METHODS: We reviewed the charts of 13 patients, seen in four medical centers, who suffered acute or chronic aortic dissection over the period 1970 through 2000 whilst under the age of 25 years. RESULTS: There were seven male and six female patients, with the mean age at diagnosis being 12.1 years, with a range from one day to 25 years. Congenital cardiac defects were present in five patients, and Marfan syndrome in four. In three of the patients with congenital cardiac defects, aortic dissection developed as a complication of medical procedures. In three patients, dissection followed blunt trauma to the chest. We could not identify any risk factors in one patient. The presenting symptoms included chest pain in four patients, abdominal pain and signs of ischemic bowel in two, non-palpable femoral pulses in one, and obstruction of the superior caval vein in one. Angiography and magnetic resonance imaging were the main diagnostic tools. Overall mortality was 38%. Only six patients had successful surgical outcomes. CONCLUSION: Due to the rarity of aortic dissection a high index of suspicion is required to reach the diagnosis in a timely manner. It should be considered in young patients complaining of chest pain in association with Marfan syndrome, anomalies of the aortic valve and arch, and chest trauma.     

Ultrafast computed tomography in the diagnosis of diseases of great vessels

Rapid and accurate detection of great vessel disease is of enormous importance in clinical practice. The search continues for the best technique to evaluate critically ill patients with acute aortic dissection and/or acute pulmonary embolism. Because of its speed and excellent spatial resolution, ultrafast computed tomography (CT) is a very useful tool and may alter the management of patients with aortic disease. Other techniques, such as magnetic resonance imaging (MRI) and transesophageal echocardiography (TEE) are also used in the diagnosis of aortic dissection. Each technique has advantages and pitfalls. At this time it is likely that one technique will complement the other. With further technical improvements, both MRI and ultrafast CT are likely to emerge as the diagnostic tests of choice. In the future, further validation and comparative studies in the acute setting may help to identify the most accurate and useful technique.     

A case report on asymptomatic ascending aortic dissection

Aortic dissection is a relatively rare but dreadful illness, often presenting with tearing chest pain and acute hemodynamic compromise. Early and accurate diagnosis and treatment are essential for survival. In the present review, a rare case of an asymptomatic ascending aortic dissection is reported. The general clinical manifestations, diagnosis and management of aortic dissection will also be reviewed.     

Magnetic resonance imaging and two-dimensional echocardiography. Alternative approach to aortography in diagnosis of aortic dissecting aneurysm

Unrecognized acute dissection of the aorta requires rapid and accurate diagnosis for appropriate management. The “gold standard” for diagnosis has been invasive angiography, but this diagnosis can be achieved noninvasively via two-dimensional echocardiography, computed tomographic scanning, and magnetic resonance imaging. Two patients are described in whom echocardiography and magnetic resonance imaging were complementary diagnostic aids. The advantages and disadvantages of echocardiography, computed tomographic scanning, magnetic resonance imaging, and aortography in aortic dissection are discussed. It is anticipated that a combination of noninvasive diagnostic aids will eliminate the need for invasive angiography in many instances in the future.     

Acute aortic dissection--vascular emergency with numerous pitfalls

Acute aortic syndrome comprises acute aortic dissection, aortic intramural haematoma and penetrating atherosclerotic ulcers of the aortic wall. It ranks, after acute coronary syndrome, as one of the most frequent acute life-threatening differential diagnoses of chest pain. Chances of survival would probably be good in the large majority of cases, assuming optimal therapeutic management including rapid diagnostic evaluation followed by immediate and appropriate treatment is provided. However, actual mortality rate in these patients is still currently higher than 40%, despite medical and surgical progress. This unfavourable prognosis for the most frequent variant of acute aortic syndrome--aortic dissection--is due to the wide variability of clinical symptoms. These are often initially unspecific and frequently lead to delays in establishing the correct diagnosis, possibly first recognised at autopsy. Even after a timely, correct diagnosis, there is still a considerably high mortality rate following surgery, even with younger patients. Whenever acute aortic dissection is suspected a diagnostic imaging study should immediately be obtained. In addition to CT angiography, transesophageal echocardiography is recommended, due to its flexibility, as the diagnostically most useful tool in this context. Based on three case reports of acute aortic dissection this paper critically discusses the problems in making a correct and timely diagnosis and also provides an overview of the current state of knowledge in the areas of pathophysiology, epidemiology, clinical symptomatology as well as appropriate case-related management and prognosis of acute aortic dissection.     

Echocardiography in aortic root dissection and dilatation.

Six patients with aortic root dissection proved by angiography, surgery or autopsy, and six patients with aortic root dilatation were studied by echocardiography. Echocardiography was diagnostic in five or six patients with dissection and suggestive in the sixth, disclosing anterior and posterior dissection in three, anterior dissection in one and posterior dissection in one. The recording of a double echo in the aorta was the diagnostic feature. Angiography was diagnostic in four of the six patients, yielded a false negative result in one and was not performed in one. Six patients with dilatation had an enlarged aortic root by echocardiography. Left ventricular size, stroke volume, ejection fraction, aortic regurgitant flow and velocity of circumferential fiber shortening were calculated in 11 patients. Echocardiography was extremely helpful in the diagnosis, management and follow-up in patients with aortic dissection or dilatation.     

Percutaneous management of penetrating aortic ulcer

Penetrating aortic ulcer is a variant of classic aortic dissection having distinct histopathological characteristics. If not appropriately treated, it evolves to combined morbidity and mortality rates as high as those of classic dissection. This condition, therefore, warrants special attention with accurate diagnosis and treatment. Percutaneous management using endoprosthesis is the method of choice, since the patients are usually elderly and have comorbidities that would increase the complication rates of traditional surgery. A 78-year-old woman complaining of thoracic pain was admitted to the hospital; her pain had been radiating to the interscapular and left lumbar regions for four months. Upon diagnostic investigation, a penetrating aortic ulcer was found, and after being successfully treated percutaneously with stent implantation, the patient became asymptomatic and is under outpatient follow-up.     

Aortic dissection--an update

Acute aortic dissection is a medical emergency with high morbidity and mortality requiring emergent diagnosis and therapy. Rapid advances in noninvasive imaging technology have facilitated the early diagnosis of this condition and should be considered in the differential diagnosis of any patient with chest, back, or abdominal pain. Emergent surgery is the treatment for patients with type A dissection while optimal medical therapy is appropriate in patients with uncomplicated type B dissection. Adequate beta-blockade is the cornerstone of medical therapy. Patients who survive acute aortic dissection need long-term medical therapy with beta-blockers and statins and appropriate serial imaging follow-up. Future advances in this field include biomarkers in the early diagnosis of acute aortic dissection and presymptomatic diagnosis with genetic screening. Overall patients with aortic dissection are at high risk for an adverse outcome and need to be managed aggressively in hospital and long term with frequent follow-up.     

Extension of dissection in stent-graft treatment of type B aortic dissection: lessons learned from endovascular experience.

Endovascular treatment is becoming the most important treatment modality in the complex management of type B dissection, providing benefits to both acute and chronic patients. Growing technical experience and improving stent-graft devices have resulted in better patient outcome and expanded clinical indications. Nevertheless, similar to any treatment option, this less invasive method has its inherent risks. Several cases of iatrogenic dissection have been reported in the literature, underlying the need for guidelines to minimize this risk and improve procedural safety. Extension of the dissection after endovascular repair of type B dissection does not appear to be device-specific, but related primarily to aortic wall alterations or adverse anatomy that arise most frequently in hypertensive patients or those with challenging aortic configuration. An accurate examination of the aortic wall and dissection anatomy and careful intraprocedural device manipulation and balloon molding may help avoid this potentially life-threatening complication.     

Diagnosis and management issues in thoracic aortic aneurysm

Thoracic aortic enlargement is an increasingly recognized condition that is often diagnosed on imaging studies performed for unrelated indications. The risk of unrecognized and untreated aortic enlargement and aneurysm includes aortic rupture and dissection which carry a high burden of morbidity and mortality. The etiologies underlying thoracic aortic enlargement are diverse and can range from degenerative or hypertension associated aortic enlargement to more rare genetic disorders. Therefore, the evaluation and management of these patients can be complex and requires knowledge of the pathophysiology associated with thoracic aortic dilation and aneurysm. Additionally, there have been important advances in the treatment available to patients with thoracic aortic disease, including an increased role of endovascular therapy. Given the risk of mortality, increased clinical recognition and advances in therapeutics, the American College of Cardiology, American Heart Association and related professional societies have recently published guidelines on the management of thoracic aortic disease. This review focuses on the pathophysiology and various etiologies that lead to thoracic aortic aneurysm along with the diagnostic modalities and management of asymptomatic patients with thoracic aortic disease.     

Aortic dissection: diagnosis, state-of-the-art of imaging and new management acquisitions.

A prompt diagnosis is the cornerstone of effective treatment of aortic dissection and it is the single most important determinant of survival in this patient population. New imaging modalities such as transesophageal echocardiography, magnetic resonance imaging, helical computed tomography and electron-beam computed tomography have been introduced during the last decade. These new imaging techniques allow for a better and earlier diagnosis of aortic diseases even in emergency situations. Bearing in mind the high overall mortality of aortic dissection, the role of prevention cannot be overstressed. The main risk factor for aortic dissection/rupture is the aortic diameter; therefore we would like to stress the role of aortic replacement as an effective preventive method for aortic dissection/rupture. Determining the right time for elective surgery, when the operative risk is lower than the risk of dilation-related complications, could contribute to a decrease in urgent surgical procedures on the ascending aorta.     

Guidelines of the Spanish Society of Cardiology on aortic diseases

Acute aortic pathology is an urgent clinical situation, of which prognosis mainly related to prompt and accurate diagnosis as well as a quick treatment. In this paper we review the aortic pathology, specially focused on aortic dissection. We review its etiology, clinical presentation and diagnostic methods. In addition the medical therapy and the surgical indications of aortic aneurysm, dissection and aortic intramural haematoma are described.     

Echocardiographic Findings Mimicking Type A Aortic Dissection

BACKGROUND: Type A aortic dissection is a rare, but life-threatening disease. The prognosis is determined by an accurate and immediate diagnosis. CASE STUDY: A patient with suspected type A dissection based on outward transesophageal echocardiography (TEE) findings is reported. Renewed TEE showed dilation of the ascending aorta with pronounced wall thickness. A membrane-like structure was found in the ascending aorta. M-mode technique revealed movement of the suspected membrane that was partially in parallel to the aortic wall. Thus, there were severe doubts on the presence of type A dissection. By contrast, typical intimal rupture was found in the descending aorta. Computed tomography (CT) and angiography showed aortic dilation and an extended wall hematoma deriving from the entry at the descending part. There was no evidence of type A dissection. CONCLUSION: TEE is a noninvasive diagnostic tool to assess aortic dissection of type A with a sensitivity of 90-98% that is equal to CT or magnetic resonance imaging (MRI) solely. Complementary use of CT or MRI could improve the diagnostic accuracy. False-positive findings could result from echocardiographic artifacts concealing an intimal flap in the ascending aorta. Echo reverberations in dilated or calcified aortas had been judged to account for this phenomenon. In the present case, it could be assumed that the extended wall hematoma in accordance with vessel dilation mimicked the membrane-like structure. Oscillation or flutter of the suspicious intimal flap independently of aortal wall movement seem to be mandatory to avoid false-positive diagnoses. Ancillary findings such as flow signals, intimal fenestration or thrombosis are helpful to enhance the diagnostic specificity of TEE.     

Accuracy of biplane and multiplane transesophageal echocardiography in diagnosis of typical acute aortic dissection and intramural hematoma

Objectives. The purpose of this study was to evaluate the diagnostic accuracy of biplane and multiplane transesophageal echocardiography in patients with suspected aortic dissection, including intramural hematoma.Background. Transesophageal echocardiography is a useful technique for rapid bedside evaluation of patients with suspected acute aortic dissection. The sensitivity of transesophageal echocardiography is high, but the diagnostic accuracy of biplane and multiplane transesophageal echocardiography for dissection and intramural hematoma is less well defined.Methods. We studied 112 consecutive patients at a major referral center who had undergone biplane or multiplane transesophageal echocardiography to identify aortic dissection. The presence, absence and type of aortic dissection (type A or B, typical dissection or intramural hematoma) were confirmed by operation or autopsy in 60 patients and by other imaging techniques in all. The accuracy of transesophageal echocardiography for ancillary findings of aortic dissection (intimal flap, fenestration and thrombosis) was assessed in the 60 patients with available surgical data.Results. Of the 112 patients, aortic dissection was present in 49 (44%); 10 of these had intramural hematom (5 with and 5 without involvement of the ascending aorta). Of the remaining 63 patients without dissection, 33 (29%) had aortic aneurysm and 30 (27%) had neither dissection nor aneurysm. The overall sensitivity and specificity of transesophageal echocardiography for the presence of dissection were 98% and 95%, respectively. The specificity for type A and type B dissection was 97% and 99%, respectively. The sensitivity and specificity for intramural hematoma was 90% and 99%, respectively. The accuracy of transesophageal echocardiography for diagnosis of acute significant aortic regurgitation and pericardial tamponade was 100%.Conclusions. Biplane and multiplane transesophageal echocardiography are highly accurate for prospective identification of the presence and site of aortic dissection, its ancillary findings and major complications in a large series of patients with varied aortic pathology, Intramural hematoma carries a high complication rate and should be treated identically with aortic dissection.