By Joe F Lau and Jeffrey W Olin
Physicians who perform percutaneous endovascular procedures encounter a multitude of vascular diseases that may masquerade as obstructive atherosclerotic arterial disease. While atherosclerosis is clearly the most common condition seen, complex inflammatory, genetic or structural processes may either not be amenable to an endovascular approach or actually be harmful and thus lead to outcomes that are not satisfactory.
The vasculitides are a group of heterogeneous disorders characterised by inflammatory destruction of blood vessels, and are usually grouped by the vessel size affected and pathology. The inflammatory process may result in stenosis, occlusion, dissection, or aneurysm.
The most commonly encountered by the vascular specialist are the large artery vasculitides such as giant cell arteritis (GCA) and Takayasu arteritis. The histopathology is virtually identical in these two diseases. Giant cell arteritis typically affects patients older than 60 years old, whereas Takayasu arteritis afflicts individuals less than 40, and both predominate in women. The large arteries such as the subclavian, carotid, renal, and occasionally leg arteries may develop stenosis or occlusion that can lead to decreased peripheral pulses, discrepancy in blood pressures between the two arms, inability to measure blood pressure, hypertension (from renal artery involvement), claudication, transient ischaemic attack or stroke. The coronary arteries may be involved, producing angina or myocardial infarction.
The long, smooth-narrowing appearance of the arteries is a distinctive angiographic feature. About one-fifth of these patients may develop aneurysms. The interventionalist should be wary of intervening during the active phase of disease. Intervention under these circumstances may lead to early restenosis or abrupt closure of the vessel. The first-line treatment for both entities is immunosuppression initially with high dose corticosteroid therapy. When the inflammatory component is resolved, percutaneous or surgical revascularisation can be undertaken if clinically warranted.
Thromboangiitis obliterans, also known as Buerger’s disease, is a non-atherosclerotic, non-inflammatory disease that typically affects small and medium-sized vessels. This vasculitis is differentiated from other vasculidites in that the vessel wall is relatively spared and there is a highly cellular thrombus. This is a disease that affects young men and women smokers. It is most often infrapopliteal and infrabrachial in distribution. Most patients present with critical limb ischaemia. There is a characteristic angiographic appearance of vessel occlusions, with normal vessels interspaced and the presence of corkscrew collaterals. The only effective therapy is complete tobacco cessation. Percutaneous therapy or surgical bypass almost always leads to failure due to the marked inflammation that is present in patients with active disease. Virtually all patients with thromb-oangiitis obliterans can be managed medically.
Behcet’s disease is a rare vasculitis of unclear etiology. Patients may present with recurrent oral aphthous ulcers, genital ulcers, uveitis, and skin lesions. The most frequent vascular abnormalities are aneurysm formation, and arterial and venous thrombosis (including coronary involvement that may lead to myocardial infarction). Endovascular procedures (i.e. thrombectomy and stent placement such as in cases of iliofemoral deep vein thromboses) performed during the active phase of this disease often leads to early re-thrombosis even when appropriate anticoagulation is used. Treatment regimen includes corticosteroids and immunosuppressive medications. Aneurysms can be treated with covered stents or surgical resection.
Fibromuscular dysplasia is a non-inflammatory, non-atherosclerotic disease that affects small and medium-sized arteries. The most common type of fibromuscular dysplasia is medial fibroplasia which is characterised by the “string of beads” appearance of the involved artery. The renal and carotid arteries are most commonly involved, but fibromuscular dysplasia has been reported in almost every other artery in the body (except the aorta). Approximately 10% of patients with fibromuscular dysplasia may also have intracranial aneurysms or aneurysm in other locations.
All patients with carotid or vertebral fibromuscular dysplasia should be screened with brain CT or MR angiography. Patients with renal artery fibromuscular dysplasia and hypertension may undergo percutaneous angioplasty, with the goal of improvement or cure of hypertension, or improvement in blood pressure control. Patients with carotid artery involvement may experience headaches, tinnitus, amaurosis fugax, transient ischaemic attack, or stroke. Angioplasty is indicated in patients who present with focal neurological involvement (transient ischaemic attack or stroke). Stent implantation should be reserved to treat dissection which can be associated with fibromuscular dysplasia. Aneurysms can be treated with coil embolization, covered stent, or surgical resection.
Two inherited connective tissue diseases, Ehlers-Danlos syndrome and Loeys-Dietz syndrome should be considered in individuals who present with aneurysm and/or dissection, particularly in those with a family history of similar vascular problems. There are several known subtypes of Ehlers-Danlos syndrome, each caused by a different gene allele with variable phenotypes and penetrance. The type that primarily involves the blood vessels (type IV) has the COL3A1 gene mutation. Patients with this genetic abnormality have very fragile blood vessels and are prone to dissection or perforation with catheter manipulation, and therefore, extra care must be taken during endovascular procedures. Aneurysms can be treated with covered stents or surgical resection.
Patients with Loeys-Dietz syndrome also present with aneurysms and dissections. The aneurysms may be rapidly expanding and are prone to rupture at smaller sizes. There is often extreme arterial tortuosity present. These patients may have widely spaced eyes (hypertelorism), a cleft palate, and/or a bifid uvula. These patients have abnormalities in transforming growth factor beta (TGF-beta 1 and 2) receptor gene mutation. While there is no cure for this disease, aneurysms should be treated promptly and the patient should be referred for genetic counselling. Clinical trials are underway using the angiotensin receptor blocking agent losartan to slow the growth of aneurysms.
Popliteal artery entrapment syndrome presents with claudication in young patients who otherwise do not have atherosclerotic risk factors. On physical exam, the foot pulses are normal, but may disappear upon passive foot dorsiflexion or active foot plantar flexion. Whereas in normal patients, in which the popliteal vessel courses between the medial and lateral heads of the gastrocnemius, the most common popliteal artery entrapment syndrome variant is the medial displacement of the popliteal artery, making it susceptible to extrinsic compression. Repeated compression and injury of the vessel may cause occlusion or aneurysm formation. Treatment involves resection of the aberrant muscle to relieve the compression, and a short surgical bypass of the occluded segment.
Cystic adventitial disease also causes claudication, particularly in young to middle-aged men. The claudication usually rapidly progresses over several months. On physical exam, the foot pulses may disappear on knee flexion (Ishikawa sign). Imaging by duplex ultrasound, CTA or MRA will demonstrate popliteal arterial stenosis cause by compression from the adventitial cyst. The disease process involves the formation of mucin-containing cysts within the adventitia of the popliteal artery wall. Initial treatment options include ultrasound or CT-guided needle aspiration of the cysts. Ultimately, because the cysts often reappear, surgical cyst excision, resection of the affected arterial segment, and placement of an interposition graft, may be necessary for severe cases. Angioplasty alone results in nearly 100% recurrence.
Joe F Lau has recently completed his cardiology fellowship and is currently the Hertzberg Fellow in Vascular Medicine and Imaging at the Mount Sinai School of Medicine, New York, USA. Jeffrey W Olin is professor of Medicine (Cardiology) and director of Vascular Medicine in the Zena and Michael A Wiener Cardiovascular Institute and the Marie-José and Henry R Kravis Center for Cardiovascular Health at the Mount Sinai Medical Center, New York, USA