Medical management of coral reef aorta through optimised diuretic use and angiotensin receptor blockade
- 1 Department of Rehabilitation Medicine, Singapore General Hospital, Singapore
- 2 Department of Internal Medicine, Singapore General Hospital, Singapore
- Correspondence to Dr Krithikaa Nadarajan; krithikaa.nadarajan@singhealth.com.sg
Abstract
Coral reef aorta (CRA) is a rare condition with potentially devastating complications. It is characterised by atherosclerotic calcification and stenosis of the visceral part of the aorta, usually occurring at the juxtarenal or suprarenal locations, and causing refractory hypertension and renal dysfunction. Surgical intervention, which is the recommended definitive treatment, is associated with significant morbidity and mortality. Endovascular stenting has been reported to be an alternative management option. To the best of our knowledge, this is the first case report to describe medical management of a patient with CRA with diuretics and angiotensin receptor blockade without surgical treatment.
Background
Although surgical management and endovascular treatment have been shown to be effective in previous studies of the rare condition known as coral reef aorta (CRA), this is the first case report to describe in detail medical management of CRA using solely diuretics and antihypertensive agents. We report here a case of CRA treated medically through careful longitudinal optimisation of antihypertensive medications of different classes including angiotensin receptor blockade. Optimised medical therapy therefore may serve as an alternative for patients who refuse invasive procedures.
Case presentation
A 50-year-old woman presented with severe giddiness and was found to have uncontrolled hypertension despite being on three antihypertensive agents, namely, nifedipine, hydrochlorothiazide and losartan. Her blood pressure on arrival was 200/63 mm Hg. Physical examination which included a funduscopy was normal. Her blood pressure, however, remained high despite increasing the dose of her antihypertensives, and she developed acute pulmonary oedema on the second day of hospitalisation. She was a non-smoker. She had a history of hypertension and a review of her medical records showed that she had multiple attendances to the emergency department for hypertensive urgency for which there had been no prior attributable cause.
Investigations
Initial blood tests revealed a raised creatine level of 107 μmol/L (37–75 μmol/L) and urea of 7.6 mmol/L (2.7–6.9 mmol/L) whereas the patient’s serum electrolytes were within normal range: serum sodium was 137 mmol/L (136–146 mmol/L), potassium was 4.4 mmol/L (3.6–5.5 mmol/L), bicarbonate was 21.2 mmol/L (19.0–29.0 mmol/L) and biochemical workup for secondary causes of hypertension was unremarkable. Other basic investigations, which included a full blood count, liver function tests and thyroid function tests, were normal. Cardiac-sensitive troponin remained within normal limits.
An ECG showed evidence of left ventricular hypertrophy, which was confirmed on the echocardiogram. Chest X-ray showed suggestions of fluid overload, which quickly progressed to florid pulmonary oedema on the next day. A renal artery doppler done as part of the workup for uncontrolled hypertension revealed a thickened abdominal aorta with up to 60% narrowing at and above the coeliac artery, with possible dissection flap at and above the inferior mesenteric artery. A referral was made to the vascular surgeon who noted poorly felt distal peripheral pulses in the bilateral lower limbs and advised for an urgent CT aortogram, which revealed a heavily calcified circumferential plaque at the thoracoabdominal-suprarenal abdominal aorta with at least moderate circumferential stenosis (figure 1).
Coronal and axial sections of the CT aortogram showing severe circumferential calcified plaque at the level of the suprarenal abdominal aorta.

Differential diagnosis
The main differential diagnosis of the patient’s flash pulmonary oedema was renal artery stenosis, of which the possible aetiologies included atherosclerosis, fibromuscular dysplasia, rheumatological diseases such as Takayasu’s arteritis, among others. However, given the extremely calcified lesions in her suprarenal aorta, the cause of her uncontrolled hypertension was deemed to be due to a functional bilateral renal artery stenosis caused by an extensively calcified lesion occluding the suprarenal abdominal aorta: a condition that is also known as CRA.
Treatment
A multidisciplinary team meeting involving vascular surgery, renal medicine and interventional radiology was held after which the patient was extensively counselled on various surgical or endovascular treatment options to relieve the obstruction. However, the patient declined all surgical and endovascular options offered.
In view of her symptoms of acute pulmonary oedema, the patient was treated with intravenous furosemide 40 mg one time per day. During the acute stage of her illness, losartan and hydrochlorothiazide were held off as her creatinine continued to rise. She was started on a beta blocker carvedilol when her symptoms of acute pulmonary oedema improved. She was also prescribed vasodilators—terazosin and hydralazine—in a sequential manner. The dose of furosemide was also gradually tapered down, and she was discharged with oral furosemide 20 mg one time per day being prescribed. The patient’s symptoms improved with medical therapy but her blood pressure on discharge was still suboptimally controlled at 180/80 mm Hg.
Outcome and follow-up
As the patient’s blood pressure control was inadequate, we added the angiotensin receptor blocker valsartan in the outpatient clinic once her renal function had stabilised. Valsartan, which was started at a dose of 40 mg one time per day, was increased sequentially to 80 mg two times per day over a period of 6 months. The patient was closely monitored and reviewed frequently in the outpatient clinic. Her blood pressure control, hydration status and renal function were monitored judiciously. She has remained well 6 months postdischarge and her home blood pressure readings are around 160/80 mm Hg; her renal function has remained stable.
Discussion
CRA is a rare disease characterised by atherosclerotic calcification and stenosis of the visceral part of the aorta. Stenosis usually occurs at the juxtarenal and suprarenal locations of the abdominal aorta.1 2 Most patients present with symptoms of severe hypertension or intermittent claudication secondary to lower limb ischaemia. Surgery which includes (1) open or laparoscopic endarterectomy, (2) insertion of bypass graft or (3) abdominal aortic stenting is recommended to address hypoperfusion-related complications secondary to stenosis of the aorta.1–5 Our patient, however, declined all surgical options offered to her despite being counselled extensively.
The pathophysiology of renal vascular hypertension in these patients is somewhat similar to patients with bilateral renal artery stenosis. Stenosis of the aorta at the suprarenal location results in bilateral renal hypoperfusion and thus induces activation of the renin-angiotensin-aldosterone system and impairs sodium excretion resulting in expansion of the extracellular fluid volume.6
Studies have shown that combination therapy with a diuretic plus an ACE inhibitor or angiotensin II receptor blocker (ARB) can control hypertension in most patients, with bilateral renal artery stenosis possibly being more effective than other antihypertensive drugs. A prospective cohort study by Chrysochou et al showed that the majority of patients (78%) with bilateral renal artery stenosis tolerated ACE or ARBs despite them being contraindicated.7 Numerous studies have proven that initiation of ACE/ARB also confers mortality benefits due to its cardioprotective effect as these patients are at an increased risk of cardiovascular disease.7 8 In accordance with these reports, our patient’s blood pressure control also improved when she was started on the ARB valsartan.
A cross-sectional study by Schlieper et al found that patients with CRA display an extreme exophytic growth of vascular calcification with low serum levels of calcification inhibitors.9 While preclinical studies have also shown that angiotensin receptor blockade can inhibit vascular calcification in a preclinical model,10 further research is needed to investigate its effects on vascular calcification in patients with CRA.
In conclusion, we describe the case of a patient with resistant hypertension secondary to coral reef syndrome whose blood pressure improved with the judicious use of multiple antihypertensive medications including ACE/ARBs. Larger cohort studies are needed to elucidate the long-term benefits of ACE/ARBs for this condition.
Learning points
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Coral reef aorta is a rare condition characterised by heavy circumferential calcification of the juxtarenal or suprarenal aorta, which should be considered in patients who present with resistant hypertension in whom other secondary causes of hypertension have been excluded.
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An examination of peripheral pulses is of extreme importance in the evaluation of patients with refractory hypertension as suprarenal visceral aortic stenosis is a possible cause of functional renal artery stenosis.
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Although surgical aortic endarterectomy, bypass grafting as well as endovascular stenting have been recommended as definitive treatment modalities, medical management should be considered in cases where patients refuse invasive procedures as in this case.
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Long-term medical management of such patients involves careful monitoring of fluid status and renal function while judiciously titrating the doses of diuretics and concurrent ACE/angiotensin II receptor blockers.
Footnotes
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Contributors Dr NEO, Dr KN and Dr HT were involved in the clinical management of the patient and shared equal loads in the writing and revising of the manuscript.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.
References
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