15th July 2024

Renovascular disease

Background

Disease of the renal arteries is an increasingly common cause of renal impairment and renal hypertension, particularly in the Western world. Reduced renal perfusion results in the upregulation of the renin-angiotensin-aldosterone system, contributing to hypertension.

There are two main types of renovascular disease:

• Atherosclerosis related renal artery stenosis (most common; 90%)
• Fibromuscular dysplasia (9%)

More rarely, renal artery dissection or embolism may give rise to the same clinical picture.  Moderate renal artery stenosis may be asymptomatic, but hypertension will eventually develop as the condition progresses.

Atherosclerosis related renal artery stenosis

This is predominantly seen in older patients who are also likely to have systemic atherosclerosis.  Patients are likely to have other associated risk factors such as hypertension, diabetes mellitus, ischaemic heart disease, a smoking history or peripheral vascular disease.  Similar to other forms of atherosclerotic disease, mild to moderate stenosis may present with little or no symptoms. In contrast, more severe disease may present with flash pulmonary oedema, hypertension and/or decline in renal function.

Fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is an idiopathic, non-inflammatory, non-atherosclerotic disease affecting the fibrous layers of the arterial walls. FMD has the propensity to affect any vascular bed but medium sized renal and cerebral arteries are the most commonly affected. Multifocal FMD causes a ‘string of bead’ appearance on magnetic resonance angiography or computed tomographic angiography, which corresponds to areas of vascular stenosis alongside areas of ‘bulging.’  A typical patient is a female between the ages of 16 and 50 with early onset or unexplained hypertension. Other symptoms depend on the distribution of vascular beds involved, for example, pulsatile tinnitus or chest pain.

Investigations & diagnosis

Serum electrolytes will be normal or appropriately deranged due to the degree of renal insufficiency. Urinalysis is generally bland; heavy proteinuria, blood or white cells should raise suspicion for an alternative diagnosis.  Screening for causes of secondary hypertension should be undertaken.

Urinary tract ultrasound is an inexpensive and non-invasive imaging technique and so should be used as a starting point.  CT angiography or MR angiography are acceptable detailed imaging modalities but if they are inconclusive and clinical suspicion remains high, catheter angiography may be considered.

Treatment

Both atherosclerosis related renal artery stenosis and fibromuscular dysplasia can be complex to treat. Multiple medications may need to be commenced to control hypertension.  Home blood pressure monitoring and referral to a specialist ‘hypertension’ clinic for monitoring of end organ damage is advised.  Revascularisation techniques such as balloon angioplasty and stent placement may be considered in cases of younger patients to reduce medication burden or in those with ‘difficult to treat’ disease.  Atherosclerotic disease has a particularly high risk of restenosis with angioplasty alone (around 90%); introduction of endovascular stenting has reduced this risk to around 20%.

References

• Herrmann SM, Textor SC. Renovascular Hypertension. Endocrinol Metab Clin North Am. 2019 Dec;48(4):765-778. doi: 10.1016/j.ecl.2019.08.007. Epub 2019 Sep 19. PMID: 31655775; PMCID: PMC7184322
• Faconti L, Morselli F, Sinha M, Chrysochou C, Chowienczyk PJ; British and Irish Hypertension Society. Fibromuscular dysplasia and hypertension-a statement on behalf of the British and Irish Hypertension Society. J Hum Hypertens. 2021 Nov;35(11):1051-1053. doi: 10.1038/s41371-020-00456-6. Epub 2020 Dec 1. PMID: 33262434
• Nair R, Vaqar S. Renovascular Hypertension. 2021 Nov 2. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 31869068