Ms. M’s BP monitoring kit was sent to the Biomedical Engineering Department for evaluation and possible recalibration. Meanwhile, because of the recent sudden changes in her BP, we admitted her to the hospital for some diagnostic testing and to refine the medical management of her hypertension.
At a follow-up interview and examination, the consulting cardiologist elicited a soft bruit in the right lateral abdomen. Based on that finding, the differential diagnosis, which had included atherosclerosis and hypertensive heart disease, was expanded to include a rule-out of renovascular hypertension and/or renovascular malignancy.
An abdominal CT, performed later that evening, revealed a narrowing of the right renal artery. Also seen was a “string of beads” or nodular appearance due to focal, annular, repetitive proliferative pathologic changes within the tunica intima and tunica media of the right renal artery (Figure 1). Subsequent arteriography confirmed a moniliform lumen of the mid portion of the right renal artery (Figure 2). Blood-flow measurements obtained during arteriography revealed a significant stenosis gradient (130 mm Hg) within the same artery.
Ms. M was discharged after 48 hours, and a follow-up sequential balloon angioplasty of the right renal artery was performed as an outpatient procedure. This interventional procedure resulted in subsequent improvement in her BP (with no increase in her pharmacologic regimen). She was instructed to continue to have her BP and cardiovascular risk factors monitored at regular intervals. There would also be a plan, at some point, to noninvasively evaluate her carotid arteries for the development of potential fibromuscular dysplasia (FMD) lesions.
According to the American Heart Association, nearly one in three American adults—73 million people—have hypertension, defined as untreated BP >140/90, or are taking antihypertensive medication.1 A compilation of the most recent National Health and Nutrition Examination Survey data—from three surveys conducted between 1999 and 2004—shows the rates of BP control for men and women, various ethnic groups, elderly people, and patients with diabetes never crossing a 45% threshold.2
Hypertension is associated with significant comorbidities. A BP >140/90 is found in about 69% of people with a first MI, 77% of those who experience a first stroke, and 74% of people with heart failure (HF). In fact, high BP precedes HF in 91% of cases, and hypertension is associated with a two- to threefold greater risk for HF.3
FMD is a noninflammatory, nonatherosclerotic disease of small- to medium-sized arteries. It affects primarily young females between the ages of 15 and 50 years; its prevalence has been estimated at between 1% and 4.4%.4,5 FMD has been demonstrated in almost every vascular bed,4-6 with at least two vascular beds being involved in as many as 28% of cases. Most frequently involved are the renal (60%–75%), the extracranial carotid and vertebral (25%–30%), and the visceral (9%) arteries, as well as the arteries supplying the extremities (5%).4 The internal carotid, mesenteric, celiac, hepatic, and iliac arteries are less commonly affected.
In patients with renal artery involvement, only 40% will be affected bilaterally. The middle and distal third of the artery are most often involved. FMD initially presents with hypertension, renal infarction, TIA, and/or stroke. Spontaneous dissection of the carotid, renal, and other visceral arteries has also been well described in the literature.4-7 FMD can be classified into three types according to the dominant arterial-wall layer involved: intimal fibroplasia (<10%), medial dysplasia (85%–90%), and adventitial (peri-arterial) fibroplasia (<1%). Spontaneous dissection has been most frequently associated with medial dysplasia.4,5
The differential diagnosis of FMD includes atherosclerotic disease, Ehlers-Danlos type IV (associated with medial fibroplasia), and vasculitis. Ehlers-Danlos type IV should be suspected only in patients with multiple aneurysms in different vasculatures. Vasculitis is easier to exclude since it is an inflammatory process and is associated with anemia, thrombocytopenia, and elevated acute phase reactants.4-6