Challenging Endovascular Treatment of Coral Reef Aorta and a Literature Review

Abstract

Coral reef aorta is a rare type of atherosclerotic disease that causes severe calcification in the abdominal aorta.

We present a case of coral reef aorta with hemodynamically significant symptomatic aortic stenosis causing intermittent claudication and bilateral cyanosis of the toes.

Despite the challenging anatomy for endovascular treatment, the patient underwent successful transfemoral endovascular stent-graft placement.

The endovascular intervention with stents is a viable alternative method and, in many cases, constitutes the first choice for the treatment of coral reef aorta.

The first description of coral reef aorta (CRA) was by Qvarfordt et al in 1984, ¹ which is characterized as a rare condition of nonnormally distributed aortic calcification leading to severe stenosis of the vessel lumen and resulting in the obstruction of the aorta and its branches.

The indication and treatment of CRA are still unclear; in symptomatic patients, surgical treatment is challenging with high morbidity and mortality rates, while the endovascular method can be useful because it is less invasive, especially in elderly patients with multiple comorbidities. ^{2 3} Only a few cases, which were treated with endovascular technique, have been published in recent literature.

Herein, we describe an elderly man with CRA-associated limb ischemia, who was successfully treated with endovascular stenting. The clinical picture, imaging investigations, and surgical treatment are discussed in this report, along with a review of similar published cases.

Case Report

A 68-year-old heavy smoker man was admitted to our clinic with a 1-year history of intermittent claudication with progressive worsening and bilateral cyanosis of the toes a few days before his admission. He was confined to a wheelchair and could barely walk a distance of 50 m. He had a history of hypertension, dyslipidemia, chronic obstructive pulmonary disease, depression, and daily alcohol consumption. Physical examination revealed the bilateral absence of femoral and distal pulses. There was no evidence of renal dysfunction. Computed tomography angiography (CTA) revealed an irregular, extensive, subtotal stenotic lesion of the infrarenal aorta ( Fig. 1 ).

Fig. 1.

Computed tomography angiography (CTA): ( A ) axial, ( B ) coronal, and ( C ) sagittal view showing stenotic calcified lesion into the lumen of the infrarenal aorta.

The intervention was performed under general anesthesia with right-side femoral access. It was impossible to access the wire due to the great stenosis of the aorta to perform angiography, so a surgical approach via the left brachial artery was necessary; the angiography confirmed the high-grade stenosis and the resulting reduction in blood flow speed ( Fig. 2A ). Ergodic crossing of wire from the nearly occluded aorta below the renal arteries with a 0.018-inch guidewire was achieved ( Fig. 2B ). Following a 6 × 40 mm balloon dilatation of the stricture ( Fig. 2C ), which appeared to be necessary, a Bentley BeGraft 14 × 60 mm is used to stent the lesion. Postdilation was performed using an 18 × 20 mm semi-compliant nylon balloon, resulting in a good expansion of the stent and the absence of residual stenosis. The stent positioning and expansion were optimal. There were no peri- or postoperative complications, and the patient was completely asymptomatic after the procedure.

Fig. 2.

( A ) Angiography shows severe stenosis of the infrarenal aorta ( arrow ). ( B ) Difficult catheterization of the severely stenotic aorta ( arrow ). ( C ) Predilation is performed using a balloon catheter. ( D ) The covered balloon-expandable stent graft is placed and inflated to the stenotic lesion at the infrarenal aorta showing a satisfactory expansion and with no obvious aortic dissection.

Discussion

In 1984, Qvarfordt et al ¹ first reported a strange pathological entity, due to the unusual atheroma that demonstrated extensive calcification of the aorta with an unknown etiology. Almost 40 years later, the pathophysiological causative factor remains uncertain, although the most likely hypothesis is the secondary calcification of a thrombus and the implication of inhibitions of insufficient calcification such as serum fetuin-A and uncarboxylated matrix Gla protein. ^{4 5}

CRA affects between 0.6 and 1.8% of the population with a predominance of women over men in a ratio of 1.6:1. It seems to be associated with comorbid conditions such as syphilis, rubella, amyloidosis, and neurofibromatosis. ⁶

The patient we describe here is not related to any of the above-mentioned factors but is associated with generalized atherosclerosis such as hypertension and tobacco and alcohol use. ⁷

The symptoms depend on the extent of the disease and involvement of aorta branches, causing mainly intermittent claudication and critical ischemia of the lower limbs and the viscera, while symptoms such as heart failure, renovascular hypertension, abdominal angina, acute kidney injury, and congestive heart failure have also been reported in the literature. ^{6 7 8}

The main symptom of our patient was the critical ischemia of the extremities, in the context of peripheral arterial disease, which led the patient to the hospital for the first time for further treatment. Although the patient met almost all the risk factors for atherosclerotic disease, he was not receiving any medication with aspirin and statin.

Endarterectomy, angioplasty, extra-anatomic bypass, stent placement, and stent-graft placement have already been identified as treatments for CRA. ^{7 8} Surgical treatment is challenging and can result in highly morbid complications and death, while extensive and circumferential calcification lurks difficulties for endovascular therapy. ⁴ However, there is general acceptance that the surgical open technique is associated with high rates of perioperative mortality (8.7–11.6%) and serious postoperative complications. ^{9 10}

A newer alternative technique is stent-graft placement, especially in selected patients. ⁷ In the last decade, the endovascular method seems to make its appearance and is the protagonist in the treatment of selected patients with CRA who cannot be treated with the open method. According to the current literature and platforms, the terms “endovascular stent-graft therapy” and “coral reef aorta” coexist and appear since 2008, and since then, only 13 articles ( Table 1 ) ^{3 4 5 8 10 11 12 13 14 15 16 17 18} have been published, most of them in the past 3 years. This is probably because vascular surgeons' familiarity with the endovascular technique and the appearance of newer and more advanced endovascular tools encourage vascular surgeons to dare to use the method. In these articles, 15 patients are described, mainly women aged over 60 years, with intermittent claudication as the main symptom. Two young people were treated for CRA with improved symptoms in the context of coarctation. All patients were treated with the endovascular technique, using different types of stents, with improvement in their symptoms.

Table 1. Recorded cases of endovascular treatment with stent graft of coral reef aorta reported in bibliographic databases and platforms ^{3 4 5 8 10 11 12 13 14 15 16 17 18} .

No.	Year	Author	Cases	Age/sex	Pathology	Level of aorta	Type of stent	Outcome
1	2008	Holfeld et al	2	76/M 84/M	Abdominal angina, intermittent claudication	Thoracic Abdominal	Gore TAG 34/150 mm prosthesis Gore TAG 28/100 mm prosthesis	Free of symptoms
2	2011	Donas et al	1	52/?	Intermittent claudication	Infrarenal	Self-expanding, balloon-expandable stents	Free of symptoms
3	2015	Bosanquet et al	1	61/M	Unresponsive hypertension	Infrarenal	Balloon-expandable uncovered stent	Free of symptoms
4	2017	Haraguchi et al	1	61/M	Intermittent claudication	Infrarenal	Radial force nitinol stent	Free of symptoms
5	2019	Vijayvergiya et al	1	71/F	Resistant hypertension	Above the origin of celiac artery	Self-expanding graft	Free of symptoms
6	2020	Gatta et al	1	70/F	Bilateral limb ischemia, abdominal pain	Thoracic	21-mm conformable thoracic stent graft	Free of symptoms
7	2020	Isoda et al	1	78/F	Intermittent claudication	Infrarenal	Balloon-expandable stent graft	Free of symptoms
8	2021	Myouchin et al	2	82/F 84/F	Intermittent claudication	Infrarenal	VIABAHN VBX balloon-expandable stent graft	Free of symptoms
9	2021	Sonawane et al	1	25/M	Systemic hypertension, weak femoral pulses	Postsubclavian	Balloon-expandable uncovered stent	Improved symptoms
10	2022	Portugaller et al	1	60/F	Upper back pain	Thoracic, suprarenal	Balloon-expandable 16/59 mm BeGraft aortic stent graft	Free of symptoms
11	2022	Le Bars et al	1	64/F	Heart failure (EF = 10%), abdominal angina, suppression of femoral pulses	Aortic arch	Two covered cobalt chromium stents (BeGraft Peripheral Stent Graft)	Improved symptoms
12	2022	Sekar et al	1	72/F	Uncontrolled hypertension, heart failure, intermittent claudication	Suprarenal	Stenting?	Improved symptoms
13	2022	Herrera Mingorance et al	1	41/F	Intense dyspnea, chest pain	Distal to the origin of the left subclavian artery	Covered BeGraft aortic stent + conformable GORE TAG thoracic stent graph	Free of symptoms

Abbreviations: EJ, ejection fraction; F, female; M, male.

Stent grafts are a different approach to the endovascular technique and, according to Chung and Mukherjee, are more appropriate for cases with severe atherosclerotic “coral reef” lesions. The risk of aorta rupture is always present, which a dangerous scenario in endovascular treatment; therefore, the vascular surgeon must be prepared for its treatment by controlling bleeding with intra-aortic balloon occlusion and then selecting a stent graft or open surgery, depending on the extent and location of bleeding. ¹⁵

Another complication that can occur is the fracture of the stent graft, due to the intensely calcified aorta, but this is restricted by the correct choice of graft size.

Endoleak in this case is not the main complication, because it is not an aneurysm that requires sealing. The possibility for stent migration is present but fortunately is limited by its hooking to the irregularly shaped atherosclerotic plaque of the aortic wall. ³

None of these potential side effects were observed in our patient. The main goal is to minimize morbidity by maximizing effectiveness and durability. However, in each case, a mandatory careful evaluation is required.

Endovascular treatment of CRA is technically possible and exempts the vascular surgeons from the concern of complex and difficult patients, deemed unsuitable for open vascular intervention. ¹²

Conclusion

The endovascular intervention with stents is a viable alternative method in selected patients and, in many cases, constitutes the first choice in hemodynamically significant symptomatic stenosis of the aorta, minimizing the morbidity and mortality and maximizing the efficacy. ¹⁹ Endovascular placement of the covered balloon-expandable stent seemed to be the best choice for us in this case, because the best result was achieved at all levels.