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| Fibromuscular Dysplasia By Josh Lee |
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Abstract
Fibromuscular Dysplasia (FMD) is a non-atherosclerotic segmental disease of unknown etiology primarily affecting muscular arteries of small to medium size. This disease affects women more than men at a three to one ratio. This disease can present in many different ways, as this article will outline. Diagnosis of FMD can be tricky at times but may also jump right out at the sonographer. These few case studies will display many different types, onsets, diagnoses, and treatments for FMD. This article should prove that the sonographer should have a great deal of knowledge and skill to aid in the diagnosis of Fibromuscular Dysplasia. |
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Keywords
Fibromuscular Dysplasia (FMD), Hyperplasia, Renal Artery Stenosis, Carotid Artery Stenosis, Renovascular Hypertension, Renal Infarction. |
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| [fig 1] Carotid FMD |
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Introduction
Click here for figures 1-3
Fibromuscular Dysplasia (FMD) is a disorder of unknown etiology that affects medium-sized arteries. This disorder normally presents in adults ages 25-50 years old. Women are affected by the disease three times more commonly than men [1]. FMD is categorized into three different types based on histological and angiographic findings in the arteries. Type one is most common and is characterized by medial fibroplasia; these cases exhibit a string-of-beads appearance on angiography [fig 3]. Type two is much less common than type one, and the primary abnormality is intimal fibroplasia. The affected arteries show long segments of concentric cylindrical narrowing [fig 3]. Type three is rare and features subadventitial fibroplasia. It is characterized by involvement of only one side of an artery wall [fig 3] [2]. The renal artery is the artery most commonly affected by FMD, followed by the carotid artery [fig 1 & 2]. Other less common arteries that may be affected are the iliac, mesenteric, and vertebral arteries [3]. FMD accounts for 25-33 % of renovascular hypertension cases, 10 % of which are bilateral. Percutaneous transluminal angioplasty with or with out a stent is the most common treatment for FMD [4]. In this paper different types of FMD case studies will be review to show how important it is for a sonographer to know the signs, symptoms, and complications of FMD. |
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Case Reports of Fibromuscular Dysplasia |
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| [fig 4] MR angiography shows a narrowing of the left internal carotid artery extra cranially. |
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Case 1
Click here for figures 4-5
A 34-year-old right-handed female was admitted to the department of neurological science of La Sapienza University of Rome with severe headaches. The patient did not present with any cerebrovascular risk factors such as cigarette smoking, diabetes, high blood pressure or oral contraceptive use. When she was 27-years-old she began suffering from migraine headaches associated with nausea and occasionally vomiting, characterized by temporal and/or frontal left pain. The patient experienced a worsening of her symptoms, which were accompanied with blurred vision, and consulted an ophthalmologist who did not notice any visual deficit but a mild ptosis and miosis in the left eye. She was admitted to the neurological department for further examination. Her blood pressure was 130/80, and the remainder of her clinical examination was normal. She underwent electrocardiography, cardiologic examination, and chest X-ray, which were all normal. Then the patient underwent Brain magnetic resonance imaging (MRI), duplex scanning, and MR angiography of the extracranial and intracranial vessels, which showed a narrowing of the left internal carotid artery (ICA) in both proximal intracranial tracts, suggestive of FMD and arterial dissection [fig 4 & 5]. The patient’s treatment consisted of intravenous heparin followed by oral anticoagulants. Within two weeks all symptoms had resolved. A duplex scan was preformed two months later, which showed complete reperfusion, and the patient began antiplatelet therapy. The patient remained asympotomatic throughout the seven-month follow-up period [5]. |
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| A. External Iliac arteries. |
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Case 2
Click here for figures 6-10
A 47-year-old female was referred to the vascular center with a 15-year history of bilateral calf pain with rapid resolution upon standing. She denied symptoms with weight bearing or prolonged standing. Her symptoms of claudication were very reproducible with exercise that consisted of two flights of stairs or less than one block at a rapid pace. Her only cardiovascular risk factor was high cholesterol. She had no family history of arterial disease, no diabetes mellitus, no hypertension and no history of tobacco use. Her physical findings consisted of a normal pulse exam with harsh bruits over the iliac and femoral arteries bilaterally. The indirect arterial studies were normal at rest. Following low-level exercise the ankle-brachial indices dropped significantly for both legs. A Subtracted aortogram was done, which depicted the classic “beads on a string” lesions of FMD involving the iliac arteries bilaterally, with less extensive involvement of both tiboperoneal trunks and the right renal artery [fig 6, 7 & 8]. Treatment used to correct the FMD was angioplasty [fig 9 & 10]. The intervention was deemed a success upon follow-up non-invasive arterial studies. The ankle-brachial indices and Doppler signals at rest and following standard exercise protocol were normal [6]. |
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| [fig 11] Hypodense triangle-shaped area in the right kidney suggestive of renal infarction. |
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Case 3
Click here for figures 11-12
A 60-year-old female presented with epigastric cramping and vomiting. Physical examination and initial laboratory work-up were unremarkable; except for severe abdominal tenderness and elevated lactate dehydrogenase. A CT scan showed a hypodense, triangle-shaped area in the right kidney suggestive of renal infarction[fig 11]. Renal duplex scanning revealed a focal increase of flow velocities followed by turbulence in multiple segments of the right renal artery. Arteriography showed multiple lesions in a “string of beads” pattern and a parenchymal filling defect, establishing the diagnosis of FMD [fig 12] [3]. |
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| [Fig 13] The patient’s angiogram showed an aneurysm on the ascending aorta |
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Case 4
Click here for figures 13-16
A 35-year-old female was brought into the emergency department in a state of acute-onset unconsciousness. There was no history of menstrual irregularity, hypertension, systemic illness or use of oral contraceptives or other drugs. Her initial assessment was a blood pressure reading of 220/120 mmHg and pulse of 96 beats per minute. She had normal brainstem response, including light, corneal and gag reflexes. Computed tomography (CT) of the brain revealed moderate brain edema, and electrocardiography revealed background activity composed of slow theta and delta waves. The echocardiographic examination demonstrated a 5.5 cm aneurismal dilatation of the ascending aorta [fig 13], as well as dissections in the aortic arch [fig 14], the left subclavian artery, the left common carotid artery, and the distal segment of the right common carotid artery [fig 15]. The brachiocephalic and right common carotid arteries had a “string-of-beads” appearance [fig 16]. Abdominal ultrasonography and renal angiography were normal. Based on these findings the patient was diagnosed with FMD. Eighteen hours after hospitalization, O2 saturation decreased and PaCO2 increased. Blood pressure started to decrease. She required mechanical ventilation, and Dopamine infusion was started. To address the elevated Cerebro-spinal fluid pressure due to brain edema, intravenous treatment with mannitol and dexamethasone was administered. Antihypertensive medications that had been applied in previous medical care were not continued. The patient died due to transtentorial herniation on the third day of hospitalization [2]. |
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| [Fig 17] Left common carotid angiography. Frontal view showing the stenosis of the horizontal segment of the middle cerebral artery. |
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Case 5
Click here for figures 17-19
patient was born at thirty-one weeks of gestation by caesarian section. His mother had been managed at the local hospital since one week before delivery because of threatened premature labor and pancreatitis. Her blood pressure and pancreatitis were kept under control. Soon after birth the young patient was managed by mechanical ventilation. His respiratory distress improved drastically at the age of two days but irritability and poor sucking developed on the sixteenth day due to severe hypertension (150/80 mmHg). Ultrasound cardiography revealed hypertensive cardiac hypertrophy. Further examination was completed and ultrasound of the abdomen revealed a small kidney on the right side. From these findings, the diagnosis of renovascular hypertension (RVH) due to congenital stenosis of right renal artery complicated by hypertensive cardiomyopathy was made. Water restriction and administration of an antihypertensive agent failed to normalize his blood pressure and improve cardiac function. On day seventy-six of his life he was moved into the neonatal intensive care unit. He was treated with an intravenous drip of nicardipine hydrochloride but his vital signs were unstable. His pulse rate was 177 beats per minute, respiratory rate was 45/min, and blood pressure was 102/57 mmHg. Chest auscultation revealed heart murmurs but other physical findings were normal. The abdominal ultrasound and CT revealed that the right kidney was 10 mm in length and the left kidney was 41 mm in length. Blood pressure could not be normalized, thus a resectioning of the right kidney was preformed at age 107 days. The resected renal artery was compatible with those of FMD. His medical condition improved and he was discharged on day 124 of his life. At the age of 8 months, he was re-admitted due to a sudden right-sided hemiconvulsion. He was also irritable with a blood pressure of 150/50 mmHg. An antihypertensive agent was administered. Physical examination revealed weakness of the left limbs and femoral pulsation. To clarify the cause of his incurable seizure and recurrent severe hypertension, angiography was preformed of the intracranial arteries, aorta, and its main branches including the left renal artery. The angiography pictures revealed FMD causing the narrowing of the intracranial carotid arteries at the level of the bifurcation, left mid-cerebral arteries and abdominal aorta with its branches including the root of the left renal artery [fig 17, 18 & 19]. At the age of 9 months FMD was diagnosed, and in an attempt to improve the blood supply to the left temporal lobe, an encephalo-duro-arterio-synagosis was preformed without success. He developed sepsis complicated by disseminated intravascular coagulation via a central venous catheter and died of massive intracranial hemorrhage at the age of 14 months. With parental permission an autopsy was preformed providing the diagnosis of FMD of the small-to middle- sized arteries, which led to involvement of multiple organs. A few of the major arteries diagnosed with extensive FMD were the renal, coronary and splenic, gastric and intestinal arteries. In addition moderate fibrous thickening of the descending aorta was also visible. The parents refused examination of the brain but the bilateral carotid arteries appeared normal. This is the youngest case of FMD published to date [7]. |
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| [Fig 20] PRE ANGIOPLASTY TRANSPLANT RENAL ARTERY |
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Case 6
An 80-year-old woman was brought to the emergency department with accelerated hypertension. Multiple medical regimens failed and a renal arteriogram was ordered which revealed FMD of the right renal artery. Percutaneous transluminal angioplasty was successful in dilating the renal artery and making the blood pressure easier to control. This 80-year-old woman is the oldest publicized person to be diagnosed with FMD up to the year 1996 [8].
A 63-year-old hypertensive female presented at a vascular lab with a 4-day history of numbness, pain, and coolness of her left hand. On physician exam the patient was found to have a normal sinus rhythm and had a cool hand with muffled pulses. The axillary and brachial pulses were normal and flow in the left ulnar artery was detectable with Doppler. Radial artery flow could not be detected with Doppler. Segmental pressures and pulse volume recordings were normal in the proximal arm but were diminished at the level of the patient’s wrist. An arteriogram revealed significant narrowing and irregularity of the brachial artery, with characteristic “beading” and complete thrombosis of the radial artery. The patient was treated overnight with an infusion of urokinase. Upon follow-up of overnight treatment the radial pulse had returned and symptoms had subsided for the patient. Subsequently the patient had a percutaneous transluminal balloon angioplasty of the involved segment of the brachial artery. The patient was followed up after surgery with pulse volume recordings and upper segmental pressures and the findings were normal [9].
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Case 7
Click here for figures 20-21
A 40-year-old male with history of hypertension, diet-controlled type II diabetes mellitus and hypercholesterolaemia, underwent a kidney transplant for end-stage renal failure secondary to hypertensive nephrosclerosis. The kidney was retrieved from a 25-year-old woman with no history of hypertension or vascular disease. The transplant was a success. The surgery had no complications and the patient had no problem controlling his hypertension, which was normal at 130/80 mmHg for ten years post surgery. Then on the tenth year post-transplant the patient was noted to have elevated blood pressure at 180/90 mmHg. The patient displayed features of vascular disease but no bruit was audible at the transplant level. Doppler ultrasound revealed a diagnosis of renal artery transplant FMD with a peak systolic velocity of 639 cm/sec. Angiography confirmed the characteristic beading of FMD in the transplant renal artery [fig 20]. Angioplasty for the region of FMD was preformed by using a 6 mm diameter balloon but without use of an intra-arterial stent [fig 21]. Two years post procedure the patient continues to have a stable blood pressure [10]. |
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Conclusion
Fibromuscular Dysplasia is an uncommon vascular disease, which results in arterial dilation and narrowing of vessel segments. There is no secret to diagnosis of FMD. The sonographer should know the signs, symptoms, and risk factors of the disease and be aware that if carotid FMD is diagnosed a renal duplex scan should be the next step to aid in the treatment of the FMD patient. With the proper knowledge and skill vascular sonographers should be able to demonstrate FMD with color, spectral, and power Doppler. Although angiography is the gold standard for diagnosis of FMD, the improved technology of today has made it possible for an accurate ultrasound diagnosis of FMD. |
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Bibliography
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[8]. Prieto, Linda Reid; Carmel Bitondo Dyer; The Oldest Patient With Fibromuscular
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