Treatment of symptomatic coral reef aorta by a nitinol self-expanding stent

Abstract

Coral reef aorta (CRA) is a rare condition, characterised by rock-hard calcification of the juxta-renal and supra-renal aorta with luminal encroachment causing significant stenosis of the aorta and its branches. It usually presents as resistant hypertension, renal dysfunction, mesenteric ischaemia, limb claudication or embolic manifestations. Although surgical thrombo-endarterectomy along with bypass graft to the affected visceral arteries remains the cornerstone of treatment, it is associated with considerable mortality and morbidity, especially in patients with pre-existing comorbidities. Here we report an elderly female of resistant hypertension, who had successful endovascular aortic stenting using a non-graft self-expanding stent. Her blood pressure dramatically improved following endovascular management. In comparison to the conventional surgical approach, endovascular stenting can be an alternative, less invasive approach in selected CRA patients.

Background

Coral reef aorta (CRA) is a rare disease of the thoracoabdominal aorta, characterised by heavy, eccentric, circumferential calcification of juxta-renal and supra-renal aortic wall with intraluminal protrusion resulting in obstruction of the aorta and its adjacent visceral arteries. Clinical manifestations depend on the severity of obstruction of the aorta and its visceral branches.^{1 2} The conventional treatment of CRA is thrombo-endarterectomy, along with bypass grafting to the affected vessels. Here we describe an elderly female of CRA-associated resistant hypertension, who was successfully treated with endovascular stenting.

Case presentation

A 71-year-old non-diabetic woman presented with long-standing uncontrolled hypertension (blood pressure 180/70 mm Hg) despite taking four drugs—olmesartan, indapamide, amlodipine and metoprolol. Bilateral lower limb pulses were feeble and the ankle-brachial index was 0.60 (normal value 0.91–1.30).

Investigations

Routine serum biochemistry including liver and renal function tests were normal. CT angiography revealed a focal eccentric densely calcified stenosis of the abdominal aorta, 10 mm above the origin of celiac artery (figure 1A,B). The minimal luminal diameter was 6.2 mm, while the aortic diameter was 19 mm (figure 1C).

Figure 1.

CT angiogram showing heavy calcification of the supra-renal aorta (A and B, white arrows), with a 70% eccentric luminal stenosis (C).

Treatment

After our institutional multidisciplinary team meeting, and informed patient consent, an endovascular approach was considered to relieve the aortic obstruction. Contrast angiogram revealed an eccentric calcified focal stenosis of the aorta (figure 2A,B), above the origin of the celiac artery, with a pressure gradient of 80 mm Hg. Mesenteric and renal arteries were normal. Following a 14×40 mm balloon dilatation (figure 2C) (Atlas balloon, Bard Peripheral Vascular, Tempe, Arizona, USA), there was a focal dissection of the aorta (figure 2D), which was covered by a 28×100 mm nitinol self-expanding non-graft stent (Sinus XL stent, OptiMed Medizinische Instrumente GmbH, Ettlingen, Germany).

Figure 2.

Contrast angiogram showing an eccentric, calcified focal aortic stenosis (A, black arrow and B). After dilatation with a 14×40 mm balloon (C), there was a focal aortic dissection (D, two black arrows for extent of dissection), which was covered by a 28×100 mm nitinol self-expanding stent with a good flow (E) and no residual gradient.

Outcome and follow-up

Postdilatation of the stented segment with a 16×40 mm balloon (Atlas balloon, Bard) resulted in a good expansion of the stent and no pressure gradient across it (figure 2E). Local femoral artery hemostasis following 11F sheath removal was achieved with a Perclose Proglide suture-based closure device (Abbott Vascular Devices, Redwood City, California, USA). Her blood pressure gradually normalised in the next 48 hours after the intervention and remained normal (120/60 mm Hg) without any antihypertensive drugs during 4 months of follow-up.

Discussion

CRA is characterised by extreme exophytic growth of vascular calcification of abdominal aorta at the level of diaphragm. The initial involvement is of the posterior wall of the aorta, which gradually progresses in a circumferential manner encroaching the intraluminal space and adjacent visceral arteries. The pathophysiology of this rare entity is not fully elucidated. Atherosclerosis and deficiency of calcification inhibitors such as serum fetuin-A and uncarboxylated Matrix Gla-Protein have been postulated as the cause for this extensive focal vascular calcification of aorta.³ The clinical manifestations of CRA depend on the severity and extent of aortic obstruction and involvement of visceral arteries. Hypertension is a common clinical presentation, while other symptoms are related to renal dysfunction, chronic mesenteric ischaemia, bilateral lower limb claudication and embolic manifestations.^{1 2} The index case had resistant, secondary hypertension due to aortic obstruction, which dramatically improved following percutaneous intervention. The conventional management of CRA is to perform trans-aortic endarterectomy with bypass graft to affected visceral arteries via an extensive thoracoabdominal approach.^{1 2} The operative mortality varies from 11.6%–14.2%, while a repeat corrective surgery is required in 16% of cases for postoperative complications.^{1 2}

Endovascular intervention can be an alternative approach in selected patients of CRA who have a focal aortic disease, and without any visceral arterial involvement. Compared with the conventional surgical approach, endovascular stenting is less invasive, associated with fewer vascular complications, shorter hospital stay and lower morbidity and mortality. Aortic graft stent has been used by a few authors to treat CRA.^{4 5} Its advantage includes adequate covering of calcified endoluminal surface to prevent downstream embolism and prevent the leak in case of aortic perforation. It also requires an adequate landing zone (15–20 mm) at supra-renal aorta to avoid covering of visceral arteries. An inadvertent coverage of thoracoabdominal spinal arteries during graft stent placement can result in spinal cord ischaemia and paraparesis. We preferred non-graft stent in the index case as there was an inadequate landing zone between CRA and the origin of celiac artery, that is, 10 mm, and a few spinal arteries were arising just above the CRA site. Few authors have used non-graft balloon expandable stent in CRA,^{6 7} which can have the risk of rupture of the calcified aorta.⁸ We preferred nitinol self-expanding stent to cover the CRA and also iatrogenic aortic dissection following balloon dilatation. There is only one published case report about the use of self-expanding stent in CRA,⁹ similar to the index case.

In conclusion, we describe an elderly female with resistant hypertension who was found to have a rare disease that is CRA. Successful endovascular stenting by a self-expanding stent could dramatically improve her resistant hypertension.

Learning points.

• Coral reef aorta is a rare disease of juxta-renal and supra-renal aorta, that presents as resistant hypertension, limb claudication, renal dysfunction, mesenteric ischaemia and peripheral embolism.

• Surgical trans-aortic endarterectomy with visceral arterial bypass remains the cornerstone of treatment, however, it carries significant morbidity and mortality.

• Percutaneous endovascular stenting can be an alternative, less invasive therapy in selected patients who have focal instead of diffuse aortic calcification, and visceral arteries are not involved. It is associated with fewer vascular complications, shorter duration of hospital stay and lower morbidity and mortality compared with conventional surgery.

• Graft or non-graft, balloon or self-expanding stent can be used for endovascular therapy. Each type of stent has its merits and demerits.