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

Abstract

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

Keywords

Intramural hematoma penetrating aortic ulcers atherosclerosis descending ascending aorta aneurysm dissection acute aortic syndrome

Introduction

Acute aortic syndromes (AAS) include a number of diseases that should be precisely diagnosed by a vascular specialist. The most common is aortic dissection, however intramural hematomas (IMH) and penetrating aortic ulcers (PAU) are uncommon variants that may represent subcategories to aortic dissection (AD) and are, most likely, early stages in the pathology of AD. Early recognition of IMH and PAU was credited to Shennan in 1934; however, more characterized reports were outlined by Stanson in 1986,¹ Cooke in 1988,² and Vilacosta in 1996, who described these syndromes and distinguished their appearance from classic dissection.³ The majority of these lesions occur in the descending thoracic aorta (90%), however up to 10% may occur in the ascending thoracic aorta.^1,2,4,5

Pathophysiology

The etiology is not well defined, but all patients have evidence of atherosclerosis. Hypertension, smoking, cystic medial necrosis, Marfan syndrome, and Ehler–Danlos syndrome are all predisposing factors.⁶

A PAU is a disruption in the intima with invasion of the media that can occur in arterial territory and appears as an outpouching (crater), but with no obvious dissection. On the other hand, IMH is a localized thickening of the aortic wall secondary to rupture vasa vasorum and localized bleeding within the media, without obvious intimal disruption that can result from a PAU, but not vice versa. Pathology details were outlined by Stanson¹ and Cooke,² who reported on 16 patients with atheromatous ulcerations in the descending thoracic aorta that penetrated the internal elastic lamina and resulted in the formation of IMH. Almost 50% of their patients experienced failed medical therapy, which included control of hypertension, pain medication, and antiplatelets. That group of patients underwent surgery for a contained rupture. Based on these results, the authors recommended aggressive surgical intervention for these pathologies, even more so than with dissecting aneurysms. Whether or not a PAU leads to progression of an IMH or AD, or is entirely distinct is unknown. However, both entities occur exclusively with atherosclerotic disease and, more commonly, in the descending thoracic aorta.

Incidence and nature of the disease

It is estimated that 2–8% of AAS consist of PAU and can occur in parallel (on the opposite arterial wall) or in series (in sequence). Stanson et al. reviewed 684 aortograms to indicate the prevalence and found PAU in 16 patients (2.3%).¹ Quint and associates reviewed the natural history of 56 PAU in 38 patients with a mean follow-up of 18.4 months.⁷ Computed tomography angiogram (CTA) was available for 33 lesions: 21 lesions remained stable, two lesions were unchanged, and 10 lesions showed a mild to moderate increase in aortic diameter. Associated IMHs regressed over 1–2 months, and 37 remained clinically stable, two were associated with recurrent chest and/or back pain, eight underwent surgical resection or thoracic endovascular aneurysm repair (TEVAR) (thoracic endograft), and two patients died. This study showed that no initial CTA finding was predictive of outcome, however pleural effusion was correlated with clinical instability. The authors concluded that most PAUs were asymptomatic and did not enlarge, but those that did were associated with ectatic aortic disease, defined as a dilation less than 1.5 times of the adjacent normal diameter area.⁷

Other reviews have indicated that PAUs can lead to saccular or fusiform aneurysm formation with a mean growth of 10% a year and rupture in up to 40% (ulcer > 12 mm in diameter).⁸ Presentation usually occurs in patients a decade older than those with AD. The most common presentation is chest pain radiating to the back (90% of patients). Other uncommon presentations include thromboembolism, abnormal chest x-ray, or incidental findings on computed tomography (CT) angiography or magnetic resonance angiography.^1,2,4,5,8

Diagnosis

The most reliable and sensitive diagnostic tool is CT angiography, which can accurately provide the nature and extent of the disease; therefore, its dominant role cannot be underestimated (Figures 1 and 2).⁵ Transesophageal echocardiography plays a complementary role in establishing a diagnosis and is imperative in regards to ascending thoracic pathology.⁹

Figure 1.

CTA axial view demonstrating an intramural hematoma (IMH).

Figure 2.

CTA sagittal view of a penetrating aortic ulcer (PAU).

Both IMH and PAU occur more commonly in the descending thoracic aorta compared to the ascending thoracic aorta, and both are associated with atherosclerosis, but especially PAUs. Another interesting clinical association is that 40% of patients with a PAU have been treated previously for an abdominal aortic aneurysm. These two entities may coexist, and both are more worrisome when seen in an already dilated aorta, particularly greater than 4 cm.

Discussion

To clarify the differences between IMH and PAU, Ganaha et al.¹⁰ analyzed 65 symptomatic patients with IMH. In this cohort, 34 patients were associated with PAU (Group A) and 31 patients had IMH (Group B). The ascending aorta (type A) was more frequently involved in Group B (eight of 31, 26%), whereas most of the patients in Group A had exclusive involvement of the descending aorta (type B, 31 of 34, 91%). Patients were subdivided into two categories, those with clinical progression and those with stable disease. Forty-eight percent of patients in Group A and 8% in Group B were in the progressive category (P = 0.002). They concluded that patients with both IMH and PAU were associated with disease progression, while patients with only an IMH had a more stable course.

Intuitively, one of the most significant outcomes is the concern that PAU is thromboembolism caused by debris within the ulcer area. In an interesting review from the University of California at Los Angeles, 10,671 consecutive autopsies were evaluated for thromboembolism; in 48 cases of nonaneurysmal mural thrombus, only eight patients (17%) were diagnosed with thromboembolism secondary to aortic wall lesions as PAU or IMH.¹¹ Interestingly, what was recognized before as cryptogenic aortic lesions, we now have a better definition on etiology, as well as pathophysiology (PAU, IMH, AD). Most of the available literature supports the view that PAUs rarely extend into the internal elastic lamina of the media,^11–13 but if they do, they can predispose to AD (Figure 3).

Figure 3.

Degree of penetrating aortic ulcer (PAU).

According to respected authorities and as outlined earlier, a significant number of patients who experienced failed medical therapy underwent surgery for a contained rupture. Based on their results, they recommend aggressive surgical intervention for these pathologies, especially for dissecting aneurysms. On the other hand, others have recommended medical treatment with proper follow-up as an effective alternative in selected patients.^13–18

Current management of IMH and PAU

There is nothing benign about aortic pathology, as every lesion, even unremarkable lesions, depending on their location, can compress the origin of the anterior spinal artery and result in paraplegia.¹⁹ Retrograde ascending AD²⁰ and degenerative aneurysmal dilation have also been recorded.²¹

Medical therapy

Lifelong aggressive blood pressure control, including β-blockers should be maintained. Almost one-third of patients with IMH will develop AD and should, therefore, follow the standard medical therapy for Stanford type B dissection, limiting surgical interventions to patients with complications. Some experts recommend surgical intervention for patients with an increase in the size of their IMH,²² persistent chest pain in spite of controlled blood pressure, or a large PAU (diameter >20 mm, depth > 10 mm).²³ Although there are sizing criteria for intervention for PAU, there is no objective data on what size we should intervene for IMH. Outcomes for patients with IMH can vary from resolution²⁴ to severe potential sequelae so close surveillance and early intervention is recommended.^25–27

Predictors of disease progression

The predictors of disease progression include sustained or recurrent pain, pleural effusion, and a significant increase in maximum diameter or maximum depth.¹⁰

Surgical intervention

Some authors have discussed the feasibility of open surgical approach in the form of resection and interposition graft placement for descending IMH or PAU with selected presentation as outlined earlier. Because of the significance of a morbid outcome, the procedure should be limited to those who are not candidates for endovascular options.^28,29 TEVAR (thoracic endografts) was first reported by Dake et al. in 1994,²⁴ and its safety, feasibility, and durability have been highlighted in patients with AAS in many other studies.^23,24–26 The sealing of PAUs with TEVAR reduces wall stress and, thus, provides stabilization of the diseased aortic segment. TEVAR is favorable in patients with focal disease in the descending thoracic aorta, especially in those with adequate landing zones ≥2 cm segment of healthy and normal caliber aorta according to the instructions for use; however, the recent and ongoing evolution in fenestrated skin grafts may challenge these criteria in the near future as it will provide an adequate landing zone in a healthy-looking aorta.

In a retrospective review of 54 patients who had TEVAR for PAUs, Eggebrecht et al.^27,28 reported a technical success rate of 96%, paraplegia in 6%, and additional interventions in 2% with Type 1 endoleaks at a median follow-up of 27 months. They concluded that TEVAR is an effective minimally invasive therapy for patients with PAUs and is associated with low procedural morbidity and mortality. Both the acute and mid-term mortality of TEVAR appear to be favorable, compared with the natural course of the disease.²⁹

Follow-up surveillance imaging for all patients with IMH or PAU is imperative secondary to the risk of aneurysmal formation. This should be continued until at least 6–8 months after complete resolution of the hematoma—in case of IMH—or stable size (depth and diameter) for PAU. All respected authorities agree that the most specific study—used for monitoring these lesions—is cross-axial CTA scan with/without contrast. The frequency of surveillance and/or follow-up is up to the physician’s discretion; however, we recommend that this be as frequent as 3 months, as the target lesions (size or depth) approach the limit for intervention.²⁶ It is worth mentioning that Tittle et al. recommended that these lesions carry about 38% risk of rupture and he suggested close follow-up and early interventions, if needed.³¹

Conclusions

These syndromes should be managed differently from a classic dissection. Early diagnosis, prompt medical therapy, and surgical intervention in select patients are essential for a better outcome.

Footnotes

Conflict of interest

None declared.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Acknowledgments

This work has not been previously presented and all authors are conversant with the paper’s contents and approve of its submission.

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