Chapter 142 - Fibromuscular dysplasia Flashcards
Fibromuscular dysplasia definition
1) Nonatheromatous noninflammatory proliferative process
2) medium sized conduit (long) arteries most common (renal, ICA)
First description of FMD
1938 String of beads appearance
Epidemiology of FMD
1) women > 90%
2) age 20-60
3) 10% familial
4) caucasians 95%
FMD and renal stenosis key points
1) 2nd most common renal stenosis
2) most common renal HTN in children
FMD associations with other factors and conditions
1) smoking
2) estrogen
3) ACE polymorphism
4) phenochromocytoma
5) Marfan
6) Alport syndrome
7) Takayasu
Pathogenesis of FMD
1) Vasovasorum damage from motion
2) long arteries with less vasovasorum more likely
3) Right renal > left renal to be affected and have ptosis
Differential diagnosis of FMD
1) Neurofibromatosis 1
2) EDS4
3) Williams syndrome
4) vasculitis
Differentiating NF1 and FMD
NF1 has characteristic skin lesions
Differentiating EDS4 from FMD
1) acrogeric dysmorphism
2) skin elasticity
3) distal joint laxity
in EDS4
Differentiating williams syndrome from FMD
1) facial dysmorphism
2) supra-aortic stenosis
3) behaviour changes
in Williams
Angiographic classification of FMD
1) Multifocal string of beads
2) focal with single area of stenosis
Histopathologic scheme of FMD
1) Intima fibroplasia (5-10%)
2) medial fibroplasia (80-85%)
3) periarterial/adventitial fibroplasia (<1%)
Secondary events from dysplastic lesions in FMD
Aneurysm 17% (1/3 in renal)
Dissection 20% (1/5 in renal)
Medial fibroplasia of FMD subdivided classes
1) Medial fibroplasia
2) perimedial fibroplasia
3) medial hyperplasia
Intimal fibroplasia key points
1) young no gender difference
2) collagen deposition in intima
3) disrupted internal elastic lamina
4) focal ring-like stenosis
Medial fibroplasia key points
1) Age 20-70
2) female:male 5-9:1
3) thinned media alrternating with thickened fibromuscular ride with collagen
4) can have secondary intimal hyperplasia
5) string of beads with beads larger than native vessel
6) distal 2/3 of main renal and branches 25%
Perimedial fibroplasia key points
1) young female < 50
2) patchy collagen deposition
3) intact external elastic lamina
4) string of bead but diameter less than native
Adventitial fibroplasia
1) no gender difference
2) collage replace normal adventitia
3) unifocal to long stenosis
Multiple vascular bed rate in FMD
2 vascular bed: 35%
3 vascular bed: 22%
difference in FMD and atherosclerotic lesions affecting renal function
FMD is mainly RAAS driven
Atherosclerosis can also be inflammatory driven
FMD natural history from asymptomatic in 4 years
1) 25% get HTN
2) 40% get FMD progression angiographically (overestimate)
Percentage of secondary hypertension in all HTN
5%
Indications for the evaluation of secondary HTN
1) require 3+ drugs
2) sudden elevation Cr and worsening HTN
3) <50 years old
4) spontaneous hypokalemia
5) bruit
6) flash pulmonary edema
Limitations of MRA and CTA in size of vessels
2mm
Gold standard for FMD diagnosis
Catheter DSA
Indication for treating FMD
1) refractory HTN
2) intolerance/noncompliance to meds
3) impaired renal function
4) renal size decreased > 1cm
BP target in fmd
BP < 140/80
in DM < 130/80
First line antiHTN drugs 5 classes
1) ACEi
2) ARB
3) beta blocker
4) CCB
5) diureticsd
Renal angioplasty in FMD key points
1) 0.15 mg nitroglycerin helps with vasospasm
2) cutting balloons not used unless IVUS shows adequate thickness of wall and not hypoplastic
3) stent usually not needed
Complications following endo treatment of FMD
1) access 3-26%
2) dissection 1.4-6.7%
3) rupture 2-6%
4) branch occlusion 1-5%
Factors that increase need for reintervention endo in FMD
1) branch vessel involvement
2) complex lesions
Indications for treating FMD with open surgery
1) complication following endo
2) concurrent aneurysm disease
Role of mannitol in renal protection
1) diuresis
2) hydroxyl free radical scavenger
Dose of mannitol for renal protection
12.5-20g
Open renal artery repair in FMD key points
1) cannot reimplant because too short
2) conduit GSV, IIA, prosthetic
3) renal protection
Autotransplantation of kidney key points
1) cold perfusion with Saline, Ringers or Wisconsin (4C, 500 ml)
2) Take patch off IVC to ease in anastamosis
Complication of open surgery in FMD
1) morbidity 19-28%
2) post-op occlusion 3.8-13%
3) restenosis 0-16%
4) vein graft dilatation late 20-44%
Pediatric causes of renal artery stenosis
1) FMD
2) developmental RAS
3) NF1
4) Moyamoya
5) Takayasu
6) Alagille syndrome
7) Williams syndrome
Percent of pediatric HTN due to RAS
8-10%
Rate of bilateral carotid FMD
35-85%
Epidemiology of carotid FMD
Female 40-60 make up 60-90% of all cases
Rate of carotid FMD causing emboli, thrombosis, dissection leading to aneurysm
< 10%
Location of lesion of carotid FMD compared to atherosclerotic
more distal in FMD
Rate of kinking in carotid FMD
5%
Rate of concurrent atherosclerotic disease in carotid FMD
20%
Rate of carotid aneurysms in carotid FMD
21.1%
Rate of carotid dissection in carotid FMD
5.6 - 75%
rate of Concurrent vertebral FMD in carotid FMD
7-38%
rate of Intracranial aneurysm and occlusive disease in carotid FMD
51%
80% solitary lesion, 20% multiple
usually same side as carotid lesion
Rate of coexisting renal FMD in carotid FMD
8-40%
Neurological symptoms on presentation in carotid FMD
1) stroke 12-27%
2) hemispheric TIA 31-42%
3) amaurosis fugax 22-28%
4) Horner 12.4%
5) cranial nerve abn 9.4%
6) focal neuro deficit 13.6%
Sensitivity and specificity of carotid bruit for carotid FMD
Sen 45.4%
Spe 93.7%
1st line treatment of asymptomatic carotid FMD
1) antiplatelet
2) monitor
Special considerations for carotid FMD different from atherosclerotic
1) multiple lesions which one to treat
2) concurrent aneurysm intracranial
3) concurrent HTN
4) contralateral asymptomatic lesion what to do
5) cannot use existing evidence on degree of stenosis
Surgical technique in carotid FMD
1) percutaneous angioplasty
2) Open dilation technique
3) open angioplasty
4) interpositional bypass
data limited for all
Open dilation of carotid FMD stroke rate
1.4-2.6%
TIA 1.4-7.7%
Cranial nerve injury 5.1-16.7%
