Aortic intramural hematoma: an increasingly recognized and potentially fatal entity

Outcomes of symptomatic penetrating aortic ulcer and intramural hematoma in the endovascular era

BACKGROUND

Although endovascular technology has resulted in a paradigm shift in treatment, medical management remains the standard of care for penetrating aortic ulcer (PAU) and intramural hematoma (IMH). This study aimed to detail the short- and long-term outcomes of symptomatic PAU/IMH.

METHODS

Institutional data on symptomatic PAU/IMH were gathered (2005-2020). The primary outcome was the composite of recurrent symptoms, radiographic progression, intervention, rupture, and death from related or unknown cause. Factors associated with the primary outcome were determined using a Fine-Gray model with death from an unrelated cause as a competing risk.

RESULTS

A total of 83 symptomatic patients treated with medical management aside from ruptures and type A dissections: 21 isolated PAU, 30 isolated IMH, and 32 IMH and PAU. Adverse outcomes included symptom recurrence in 14 (16.9%), radiographic progression to dissection or saccular aneurysm in 17 (20.5%), surgery in 20 (24.1%) (17 thoracic endovascular aortic repair, 1 endovascular aortic repair, 1 frozen elephant trunk, and 1 open repair), and rupture in 4 (4.8%). Twenty-seven patients (32.5%) died during follow-up: 6 from IMH treatment complications, 8 from an unknown cause, and 13 from other causes. The 30-day, 1-year, and 5-year cumulative incidences of the primary outcome was 26.5% (95% confidence interval [CI], 16.9%-37.0%), 44.9% (95% CI, 32.8%-56.2%), and 57.5% (95% CI, 42.4%-69.9%), respectively. IMH with PAU was associated with a significantly higher risk of the primary outcome compared with isolated IMH (subdistribution hazard ratio, 2.21; 95% CI, 1.09-4.50; P = .027) and isolated PAU (subdistribution hazard ratio, 3.58; 95% CI, 1.44-8.88; P = .006).

CONCLUSIONS

Complications from symptomatic PAU and IMH are frequent, with intervention, recurrent symptoms, radiographic progression, rupture, or death affecting 25% of patients at 30 days after diagnosis and almost one-half of patients 1 year after diagnosis. Given the high rate of adverse events in this population, investigation into a more aggressive interventional strategy may warranted, especially in patients with a combined IMH and PAU.

Intramural hematoma and penetrating ulcer in the descending aorta: differences and similarities

Acute aortic syndromes include a variety of overlapping clinical and anatomic diseases. Intramural hematoma (IMH), penetrating atherosclerotic ulcer (PAU), and aortic dissection can occur as isolated processes or can be found in association. All these entities are potentially life threatening, so prompt diagnosis and treatment is of paramount importance. IMH and PAU affect patients with atherosclerotic risk factors and are located in the descending aorta in 60-70% of cases. IMH diagnosis can be correctly made in most cases. Aortic ulcer is a morphologic entity which comprises several entities-the differential diagnosis includes PAU, focal intimal disruptions (FID) in the context of IMH evolution and ulcerated atherosclerotic plaque. The pathophysiologic mechanism, evolution and prognosis differ somewhat between these entities. However, most PAU are diagnosed incidentally outside the acute phase. Persistent pain despite medical treatment, hemodynamic instability, maximum aortic diameter (MAD) >55 mm, significant periaortic hemorrhage and FID in acute phase of IMH are predictors of acute-phase mortality. In these cases, TEVAR or open surgery should be considered. In non-complicated IMH or PAU, without significant aortic enlargement, strict control of cardiovascular risk factors and frequent follow-up imaging appears to be a safe management strategy.

[Type A intramural hematoma of aorta: An undervalued clinical entity]

Intramural hematoma of the ascending aorta occurs after rupture of the vasa vasorum. Previously considered as a first step of acute aortic dissection, it was later defined as a separate entity that may or may not lead to arterial dissection. The debate about the most appropriate treatment for a 69-year-old patient with intramural hematoma of the ascending aorta, led to this extensive review of the literature demonstrating that intramural hematoma type A is a life-threatening condition requiring urgent surgical support.

Aortic intramural hemorrhage: A distinct disease entity with mystery

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

Multi-component model of intramural hematoma

A novel multi-component model is introduced for studying interaction between blood flow and deforming aortic wall with intramural hematoma (IMH). The aortic wall is simulated by a composite structure submodel representing material properties of the three main wall layers. The IMH is described by a poroelasticity submodel which takes into account both the pressure inside hematoma and its deformation. The submodel of the hematoma is fully coupled with the aortic submodel as well as with the submodel of the pulsatile blood flow. Model simulations are used to investigate the relation between the peak wall stress, hematoma thickness and permeability in patients of different age. The results indicate that an increase in hematoma thickness leads to larger wall stress, which is in agreement with clinical data. Further simulations demonstrate that a hematoma with smaller permeability results in larger wall stress, suggesting that blood coagulation in hematoma might increase its mechanical stability. This is in agreement with previous experimental observations of coagulation having a beneficial effect on the condition of a patient with the IMH.

Cardiac Mass, Aortic Intramural Hematoma, and IgG4-related Disease: A Case Report

As a designated entity within medicine, immunoglobulin G4 (IgG4)-related disease is relatively new. It is immune-mediated origin, characterized by a tendency for formation of tumefactive lesions, the infiltration of IgG4-positive plasma cells, and frequent but not invariable elevations of IgG4 levels in the serum. IgG4-related cardiac mass accompanying aortic intramural hematoma is an extremely rare clinical presentation. Herein we present the case of a patient who was admitted to our department complaining of severe chest pain. Computed tomographic angiography examination revealed a cardiac mass accompanying an aortic intramural hematoma. He underwent a surgical resection of the cardiac mass and a replacement of the ascending aorta with Hemashield Platinum graft and made an uneventful recovery. A diagnosis of an IgG4-related disease was made based on laboratory results and pathological examination. Corticosteroids were administered postoperatively. This case shows that the heart itself can also be a potential site for IgG4-related disease.

Pancreaticoduodenal artery aneurysm associated with coeliac artery occlusion from an aortic intramural hematoma

Pancreaticoduodenal artery aneurysms are a rare type of visceral artery aneurysm, whose rupture is associated with high mortality. These aneurysms are of particular interest because local haemodynamic change caused by coeliac artery obstruction plays an important role in their development. However, the pathophysiological mechanism of coeliac artery obstruction is not completely understood. Pressure from the median arcuate ligament is most frequently reported cause. Although it is well-known that stenosis or occlusion of the visceral vessels may be caused by aortic syndrome, reports of pancreaticoduodenal artery aneurysm associated with coeliac artery occlusion due to aortic syndrome are extremely rare. Our case indicates a new aetiology for a pancreaticoduodenal artery aneurysm and demonstrates the rapid deterioration of the patient affected.

The Acute Abdominal Aorta

Acute disorders of the abdominal aorta are potentially lethal conditions that require prompt evaluation and treatment. Computed tomography (CT) is the primary imaging method for evaluating these conditions because of its availability and speed. Volumetric CT acquisition with multiplanar reconstruction and three-dimensional analysis is now the standard technique for evaluating the aorta. MR imaging may be useful for select applications in stable patients in whom rupture has been excluded. Imaging is indispensable for diagnosis and treatment planning, because management has shifted toward endoluminal repair. Acute abdominal aortic conditions most commonly are complications of aneurysms and atherosclerosis.

Retrograde dissection during percutaneous coronary intervention: sealing of the entry site by covered stent implantation

We present a case of iatrogenic aortic haematoma, developed during percutaneous coronary intervention, treated with covered stent implantation followed by a conservative approach characterised by the integration of both clinical and multimodal imaging information. This complication can lead to overt aortic dissection (28-47%), rupture (20-45%) or death (21%). In 10% of the cases it can completely regress. Guidelines for its treatment are debated because of the unpredictable natural history of intramural haematoma. Nowadays, a close follow-up with multimodal imaging is considered a valid strategy for the appropriate management of this severe condition. On the basis of the patient's clinical condition and the information obtained by multiple imaging tests (angiography, transthoracic and transesophageal echocardiography and multidetector CT scan) we decided to treat our patient with medical therapy. To date, a 1-year follow-up negative for cardiac events is recorded.

An under Recognized Cause of Chest Pain

Aortic intramural hematoma (IMH) is related to but is pathologically distinct from aortic dissection. In this potentially lethal entity, there is hemorrhage into the aortic media in the absence of an intimal tear. With recent advances in imaging techniques, IMH is now increasingly recognized. The limited data available suggest that the clinical course of IMH mimics that of acute aortic dissection, and mortality rates are similar. Physicians need to be cognizant regarding this entity when they are evaluating chest pain. Here we report a case of IMH, in a 63-year-old female, which was managed conservatively.

Echocardiographic Delineation of Type a Aortic Dissection

Introduction

In addition to proving the visualisation data, studies on the intimal flaps of aortic dissection based on echocardiography have been very limited.

Methods

Twenty-seven patients undergoing an operation of type A aortic dissection with preoperative transthoracic and/or intraoperative transesophageal echocardiography archived in the Horizon Cardiology Web of the hospital available for review and measurement were selected into this retrospective study. By way of quantitative and qualitative approaches, flap movement, dissection extent and aortic obstruction were sufficiently evaluated.

Results

An intimal flap was visualised in 22 (81.5%) patients and linear artifact was viewed in 1 (3.7%), and in the remaining 4 (14.8%), neither an intimal flap nor a linear artifact was visible. Dissection extents were 2.78±1.53 cm and 2.03±1.19 cm in the horizontal and vertical direction, respectively. Sub- or semi-circumferential dissection was noted in 14 (51.8%) patients. No total circumferential dissection was found in this patient population with type A aortic dissection. The obstruction of the aortic valve orifice or aortic cavity developed in 11 (40.7%) patients. Flow disturbance and thrombus in the false lumen were visualised in 24 (88.9%) and 4 (14.8%) patients, respectively. The breadth of flap movement in short-axis plane was much larger in the Aortic Obstruction Group than that of the Non-Obstruction Group (1.55±1.14 cm vs. 0.75±0.526 cm, p <0.05).

Conclusions

Preoperative transthoracic or transesophageal echocardiographic evaluations offer a convenient and precise diagnostic tool for aortic dissection. The dissection extent may directly correlate and substantially reflect the clinical symptoms of the patients with type A aortic dissection in response to the haemodynamic impairment. Preoperative echocardiographic delineation would assure adequate means and extent of the impending operation.

Endovascular treatment of thoracic dissection

Type A aortic dissection remains fatal if untreated. Although classical medical therapy for type B dissection is considered the therapy of choice in uncomplicated cases, the paradigm is changing as greater experience is accrued with endovascular treatments and technical advances improve the long-term outlook. Diagnosis is also becoming more sophisticated, allowing greater appreciation of the anatomy of dissections and improving the knowledge base as their natural history is assessed.

Computed tomography of aortic intramural hematoma and thrombosed dissection

A retrospective study was undertaken to evaluate the appearance of the aortic wall on computed tomography for the purpose of developing criteria for differentiating acute aortic intramural hematoma from thrombosed false lumen seen in aortic dissection. Computed tomography angiography findings of the thoracoabdominal aorta in 23 patients with suspected intramural hematoma and 25 with thrombosed false lumen were reviewed. The more common features of an intramural hematoma were hyperattenuation of the aortic wall, wall thickness less than a quarter of the aortic diameter, intrinsic wall calcification, a lesion extending around the entire aortic circumference, and ulcer-like projections that may be precursors of intramural hematoma. Wall thickness less than a quarter of the aortic diameter, lesion extending around the entire aortic circumference, and ulcer-like projections were the most useful indicators for distinguishing intramural hematoma from the thrombosed false lumen in aortic dissection.

Natural history of spontaneous aortic intramural hematoma progression: six years follow-up with cardiovascular magnetic resonance

We described a 6 years follow-up of a spontaneous aortic intramural hematoma (IMH) with cardiovascular magnetic resonance (CMR) examination. Since multiple factors may play roles in the natural history of IMH, the patient experienced the course of progression, which included hematoma absorption, ulcer-like lesion, aneurysm and limited dissection. The initial and follow-up CMR examination included 3D CE MRA and non-enhanced "bright blood" pulse sequence. The inherent advantage of outstanding contrast with plain scan, which shorten the scan time and avoid potential risk of contrast agent, might make the fast gradient echo sequence as an alternative method when following stable IMH.

Natural history and CT appearances of aortic intramural hematoma

Rupture of the vasa vasorum into the media of the aortic wall results in an aortic intramural hematoma. Characteristic findings of an aortic intramural hematoma include a crescentic hyperattenuating fluid collection at unenhanced computed tomography (CT) and a smooth, nonenhancing, thickened aortic wall at contrast material-enhanced CT. The CT appearance of untreated intramural hematomas evolves over time, and decreased attenuation is a clue to the chronicity of a hematoma. CT is particularly useful for evaluating aortic intramural hematomas because it allows their differentiation from aortic dissections, which have similar clinical manifestations, and permits an exact determination of their location-crucial information for surgical planning. On the basis of CT findings, some hematomas may be expected to resolve spontaneously, whereas others may be identified as posing a high risk for serious complications such as aortic dissection, aneurysm, and rupture. Appropriate clinical management is aided by accurate recognition of diagnostically specific CT features and awareness of their significance.

Pathophysiology, diagnosis, and management of aortic dissection

Aortic dissection is an uncommon but potentially fatal disease with catastrophic complications. A high level of suspicion is required for successful diagnosis as presenting symptoms are so variable that dissection may be overlooked in up to 39% of cases. It most commonly presents in the elderly population with a history of chronic hypertension. Rapid intervention is necessary as delay leads to higher mortality. Despite advances in diagnostic and therapeutic techniques, morbidity and mortality remains high. Advances in diagnostic imaging have raised the awareness of variants of aortic dissection, including intramural hemorrhage and penetrating aortic ulcer. This distinction is important as the clinical course of these variants differs from that of classical aortic dissection, and thus treatment may also differ. Understanding of these variants has also led to the recognition of markers that may help predict progression to classical aortic dissection and thus warrant closer vigilance in selected patient populations. The recognition that rapid diagnosis is required for management of aortic dissection has led to the investigation of serum tests as diagnostic aids. Serum smooth muscle myosin heavy chain, d-dimer, and serum soluble elastin fragments are promising tests that may help raise suspicion for the diagnosis of acute aortic dissection. The high mortality associated with surgical therapy has led to investigation of alternative approaches. Endovascular therapy has emerged as a viable option in patients with type B dissection who are too unstable for surgery. However, long-term follow up is required to validate this procedure.

What to Do When Evidence is Lacking — Implications on Treatment of Aortic Ulcers, Pseudoaneurysms and Aorto-Enteric Fistulae

Present knowledge on natural history and how to treat penetrating aortic ulcers or different forms of pseudoaneurysms with or without infection is limited as there are only case reports and small series of unusual aortic pathology and its treatment available.

Material:

From our centre we collected 65 patients treated with open (n=15) or endovascular reconstruction (n=50) during a 20-year period in the abdominal aorta. These patients are presented including a review of contemporary treatment.

Results:

Endovascular reconstructions seem to reduce morbidity and mortality compared to otherwise extensive open surgery. Even for patients with infectious etiology (mycotic aneurysms, aorto-enteric fistula) endovascular treatment may be a first-hand option bridging to a more elective open repair. However, a large proportion of patients being unfit for further open surgery were solely treated endovascularly and had no major infectious complications in the follow-up. Registers of cases with unusual aortic pathology, not only of those treated but also of those managed conservatively, are needed to define who to treat and if endovascular or open repair should be recommended.

Conclusion:

Endovascular technique is a promising technique for treatment of aortic pseudoaneurysms of different etiologies. We firmly recommend, despite the lack of evidence, that the work up of patients with penetrating aortic ulcers, mycotic or other types of pseudoanerysms as well as aorto-enteric fistulae should enclose both endovascular and open (or combined) treatment modalities. However, our knowledge of the natural history is limited. Therefore, registers of cases with unusual aortic pathology, not only of those treated but also of those managed conservatively, are needed to define who to treat and if endovascular or open repair should be recommended.

International Heterogeneity in Diagnostic Frequency and Clinical Outcomes of Ascending Aortic Intramural Hematoma

BACKGROUND

Differing diagnostic frequencies and management strategies for intramural hematoma (IMH) have been described in North American (NA)/European and Japanese/Korean studies.

METHODS

All publications including type-A aortic IMH were reviewed for details on patient demographics, treatment strategy, and clinical outcomes. Publications were stratified by the geographic region (NA/Europe or Japan/Korea).

RESULTS

IMH, as a percentage of aortic dissection, occurs more frequently in Japan/Korea versus NA/Europe (31.7% vs 10.9%, P < .0001). The proportion of patients treated with early medical therapy is greater in Japanese/Korean studies (77.9% vs 48.8% in NA/Europe, P < .0001). However, the overall mortality is significantly lower in Japan/Korea compared with NA/Europe (9.4% vs 20.6%, odds ratio = 2.80, P = .003) in part because of the lower mortality with early medical therapy (7.8% vs 33.3%, P < .0001).

CONCLUSION

There is significant international heterogeneity in the diagnosis and clinical outcomes of ascending IMH. IMH is diagnosed more frequently and has better overall outcomes in Japan/Korea.

Periaortic lymphoma as a mimic of posttraumatic intramural hematoma

Computed tomography (CT) of an 87-year-old man who presented to the emergency department with chest pain after a motor vehicle collision demonstrated multiple broken ribs and a thoracic periaortic soft tissue mass which was high density on precontrast images and enhanced postcontrast. The scan also demonstrated a mass encircling the left ureter and masses in the axilla and pelvis. The enhancement of the periaortic lesion and the presence of the additional soft tissue masses suggested lymphoma as opposed to intramural hematoma (IMH). The diagnosis of follicular B-cell lymphoma was rapidly confirmed with fluorodeoxyglucose-positron emission tomography/CT and excisional biopsy of the axillary lymph node. While this is an atypical presentation, lymphoma and other extravascular pathology must be considered in the evaluation of a periaortic high attenuation mass seen on CT.

Gene expression in acute Stanford type A dissection: a comparative microarray study

Background

We compared gene expression profiles in acutely dissected aorta with those in normal control aorta.

Materials and methods

Ascending aorta specimen from patients with an acute Stanford A-dissection were taken during surgery and compared with those from normal ascending aorta from multiorgan donors using the BD Atlas™ Human1.2 Array I, BD Atlas™ Human Cardiovascular Array and the Affymetrix HG-U133A GeneChip^®. For analysis only genes with strong signals of more than 70 percent of the mean signal of all spots on the array were accepted as being expressed. Quantitative real-time polymerase chain reaction (RT-PCR) was used to confirm regulation of expression of a subset of 24 genes known to be involved in aortic structure and function.

Results

According to our definition expression profiling of aorta tissue specimens revealed an expression of 19.1% to 23.5% of the genes listed on the arrays. Of those 15.7% to 28.9% were differently expressed in dissected and control aorta specimens. Several genes that encode for extracellular matrix components such as collagen IV α2 and -α5, collagen VI α3, collagen XIV α1, collagen XVIII α1 and elastin were down-regulated in aortic dissection, whereas levels of matrix metalloproteinases-11, -14 and -19 were increased. Some genes coding for cell to cell adhesion, cell to matrix signaling (e.g., polycystin1 and -2), cytoskeleton, as well as several myofibrillar genes (e.g., α-actinin, tropomyosin, gelsolin) were found to be down-regulated. Not surprisingly, some genes associated with chronic inflammation such as interleukin -2, -6 and -8, were up-regulated in dissection.

Conclusion

Our results demonstrate the complexity of the dissecting process on a molecular level. Genes coding for the integrity and strength of the aortic wall were down-regulated whereas components of inflammatory response were up-regulated. Altered patterns of gene expression indicate a pre-existing structural failure, which is probably a consequence of insufficient remodeling of the aortic wall resulting in further aortic dissection.

A case report of type I acute aortic intramural hematoma with localized dissection as a complication of renal artery stenting

Percutaneous renal artery stenting has been demonstrated as an effective procedure to improve blood pressure control and preserve renal function of patients with artherosclerotic renal artery stenosis. Although it is a relatively safe procedure, some serious complications, including retroperitoneal hemorrhage, atheroembolism, and arterial dissection, can occur. However, development of aortic intramural hematoma (AIH), a different clinical disease entity from the aortic dissection, has not been reported as a complication of the procedure. We report a unique case with AIH that was successfully treated with medication. A 71-year-old woman with uncontrolled hypertension underwent percutaneous renal artery stenting for treatment of the ostial stenosis of the right renal artery. Immediately after implantation of the stent, she complained of severe back pain and her systolic blood pressure dropped from 170 to 80 mm Hg. Aortography showed about 5 cm-sized localized dissection arising from the ostium of the right renal artery; however, computerized tomography (CT) scans taken immediately after the procedure revealed DeBakey type I AIH with a localized dissection from the right renal artery and pericardial effusion. Because of her refusal to take surgical intervention, which is a standard treatment, she was stabilized with intensive medical treatment. After 14 days of stabilization, AIH and pericardial effusion resolved on the follow-up CT scans. Her blood pressure was well controlled with oral antihypertensive medications and she was discharged without other complication.

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.

Multidetector CT of the thoracic aorta

Recent advancement of MDCT provides high-resolution axial images with optimal contrast enhancement and 3D reformatted images of the thoracic aorta. MDCT is now playing a dominant and critical role in the evaluation of thoracic aortic disease. This article will focus on procedural considerations of MDCT: acquisition parameters, contrast injection and post-processing techniques and imaging findings of thoracic aortic diseases including, aortic dissection, intramural hematoma, penetrating atherosclerotic ulcer, aneurysm, and traumatic injury.

Role of MRI in clinical cardiology

Rapid progress has been made in cardiac MRI (CMRI) over the past decade, which has firmly established it as a reliable and clinically important technique for assessment of cardiac structure, function, perfusion, and myocardial viability. Its versatility and accuracy is unmatched by any other individual imaging modality. CMRI is non-invasive and has high spatial resolution and avoids use of potentially nephrotoxic contrast agent or radiation. It has been extensively studied against other established non-invasive imaging modalities and has been shown to be superior in many scenarios, particularly with respect to assessment of cardiac and great vessel morphology and left ventricular function. Furthermore, its clinical use continues to expand with increasing experience and proliferation of CMRI centres. As worldwide prevalence of cardiovascular disease continues to rise, CMRI provides opportunity for improved and cost-effective non-invasive assessment. Continued progress in CMRI technology promises to further widen its clinical application in coronary imaging, myocardial perfusion, comprehensive assessment of valves, and plaque characterisation.

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

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

CT and MR imaging of the thoracic aorta: current techniques and clinical applications

Disease of the thoracic aorta can present with a broad clinical spectrum of symptoms and signs. The accepted diagnostic gold standard, selective digital subtraction angiography, is now being challenged by state-of-the-art CT angiography (CTA) and MR angiography(MRA). Currently, in many centers, cross-sectional imaging modalities are being used as the first line of diagnosis to evaluate the cardiovascular system, and conventional angiography is reserved for therapeutic intervention. Understanding the principles of CTA and MRA techniques is essential to acquire diagnostic images consistently. This article reviews current CTA and MRA methods used in the evaluation of thoracic aortic disease.

Aortic intramural hematoma: Current diagnostic and therapeutic recommendations

Aortic intramural hematoma (IMH) is an acute, potentially lethal disorder that is similar to but pathologically distinct from acute aortic dissection. Although hemorrhage into the aortic media occurs in both disorders, an intimal tear with resultant false lumen is not present in IMH. Instead, hemorrhage occurs within the aortic wall either due to rupture of the vasa vasorum or, less commonly, because of an atherosclerotic penetrating aortic ulcer. The most common risk factors associated with IMH are hypertension, atherosclerosis, and advanced age. IMH is life-threatening because the hematoma may extend along or rupture through the aorta, leading to hemothorax, cardiac tamponade, stroke, mesenteric ischemia, or renal insufficiency. Optimal treatment is still somewhat controversial; however, there is no question that hypertension must be treated effectively and immediately. This is usually best accomplished by intravenous infusion of beta-blocking agents, with or without the addition of sodium nitroprusside. Recent studies support surgical treatment (ie, aortic root replacement) for IMH involving the ascending aorta, although some subsets of this population may be at lower risk and may benefit from medical therapy alone. In patients with IMH involving only the descending aorta, medical therapy alone is recommended (unless impending rupture, aortic aneurysm, or end-organ ischemia occurs). Patients who survive the acute event require intensive treatment of hypertension and frequent follow-up examinations. Because this population (especially the subset with penetrating aortic ulceration) is at high risk for aortic aneurysm and rupture, serial imaging studies of the aorta are essential.

Multidetector row computed tomography of the aorta and peripheral arteries

MDCT represents a significant advance on SDCT and the advantages it brings are particularly clear in CTA applications. It allows cost effective assessment of longer segments of vascular territories to be imaged with higher spatial, contrast, and temporal resolution. It has replaced SDCT as the new CT standard and its technical abilities are rapidly approaching the temporal resolution of EBCT. With 3-D post processing tools its main benefit is in imaging studies customized to the patient's pathology, with greater measurement accuracy and reliable longitudinal assessment. MDCTA is increasingly applied not to individual vascular territories but to a complete assessment dictated by the pathology, such as the entire aorta and branch vessels in aneurysm evaluation and the aorta and the coronary arteries in dissection cases or the vascular and non-vascular chest in acute chest pain. Greater accuracy of vessel assessment will lead to a refinement of interventional and surgical techniques for an individual patient and facilitates conservative management of conditions that can be reliably monitored non-invasively and the development of intervention criteria. MDCTA will continue to increase its major role in peripheral vascular evaluation in the future though its reliability in assessing small vessels below the knee and in the foot remains to be conclusively proven to obviate the need for diagnostic catheter angiography.

Aortic intramural hematoma with severe aortic regurgitation

A 71-year-old Japanese woman with severe chest pain was diagnosed with Stanford type A acute aortic dissection. After 3 months of medical treatment, she was operated on under a diagnosis of dissecting aneurysm of the ascending aorta and severe aortic regurgitation. Operative findings showed prolapse of the redundant aortic leaflets and a dilated ascending aorta without intimal tears. Operative and computed tomography findings differed from those of a classical dissection, which was the primary diagnosis of this patient, and were compatible with a diagnosis of aortic intramural hematoma (IMH). Few reports of IMH include concomitant aortic regurgitation. Surgery involved aortic root remodeling and prosthetic graft replacement of the ascending aorta.

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.