arterial fibrodysplasia encompasses a heterogenous group of arterial dysplastic lesions affecting...

55
Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described in every artery Most common: Renal

Upload: taylor-shingler

Post on 29-Mar-2015

215 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Arterial Fibrodysplasia

•Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries

•Unknown etiology

•Described in every artery

•Most common: Renal

Page 2: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Arterial Fibrodysplasia

•Dysplastic process usually results in stenosis, but can also cause aneurysms

•Occlusive renal artery lesions: most common cause of surgically correctable HTN

•Renovascular HTN:

•Goldblatt H 1934: Established link between renal ischemia and hypertension using constricting clamp

•Atherosclerotic disease most common (>90%)

•Fibrodysplastic disease second (0.5% of general population)

Page 3: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Arterial Fibrodysplasia

•Renal artery fibrodysplasia:

•Pathology

•Clinical manifestations

•Indications for therapeutic intervention

•Drug Therapy

•PTRA

•Role of surgery

Page 4: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Pathology

•Arterial dysplasia: categorized according to layer of wall involved

•1) intimal fibroplasia

•2) medial hyperplasia

•3) medial fibroplasia

•4) perimedial dysplasia

•5) developmental stenoses

Distinct pathologic processes

Continuum of same disease

Page 5: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Pathology

•Intimal fibroplasia:

•5% of all fibrodysplastic renal artery lesions

•Affects children and adults equally

•Occurs as long tubular stenosis in children, smooth focal stenoses in adults

•Progression slower than medial fibroplasia

Page 6: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Pathology

•Medial hyperplasia:

•1% of fibrodysplastic renal artery lesions

•Angiographically similar to intimal hyperplasia

•Most often in women (30 to 50 y.o.)

•Usually as isolated lesion in midportion of main renal artery

Page 7: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Pathology

•Medial fibroplasia:

•85% of all dysplastic renal artery lesions

•White women (30-40 y.o.)

•Bilateral in 55%, when unilateral 80% are on the right

•Angiographic appearance: classic “string of beads”

Page 8: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Pathology

•Perimedial dysplasia:

•Accumulation of elastic tissue at media-adventitia junction

•10% of arterial dysplastic lesions

•Younger women

•Either focal stenoses or multiple stenoses of main renal artery

Page 9: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Etiology

•Unknown

•3 factors:

•Hormonal influences

•Arterial wall ischemia

•Mechanical stresses

Page 10: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Pathology

•Higher incidence of arterial dysplasia in women of reproductive years: role of estrogen

•?Ischemia of artery wall secondary to injury of vasa vasorum of vessels

•Repeated stretching of vessels may trigger a fibroproliferative response (right renal artery is longer and may be subject to greater axial stretch)

Page 11: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Clinical Manifestations

•Prevalence of renovascular HTN in patients with HTN is low (2-5%)

•HTN caused by arterial fibrodysplasia is even less common

•First lesson in dx renovascular HTN: recognizing clinical cues

Page 12: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

160 180

Page 13: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Pathology

•Stanley JC et al.

•U Mich series

•88% with renal arterial fibrodysplasia causing renovascular HTN showed atypical media-perimedial dysplasia

•33 boys (mean age 9.5), 24 girls (12)

•Average duration of HTN(14.2 months)

•Mean BP before drug therapy: 181/117

•Mean BP after drug therapy: 158/104

Page 14: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Pathology

•Stanley JC et al.

•U Mich series

•133 women, 11 men

•Mean age: M 31; F 39

•Average duration of HTN: 43 months

•BP before therapy: 206/122

•BP after durg treatment: 184/111

Page 15: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Depend largely on age at presentation

•Pediatrics: incidence of essential HTN is negligible

•Most instances of HTN in this patient population represent a renovascular etiology

•Mod to severe BP elevations in this patient population: detailed diagnostic studies warranted in search of correctable cause of HTN

Page 16: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Indications for intervention in adults:

•Presence of moderate to severe HTN

•HD significant renal artery stenosis

•Evidence of the functional importance of the stenosis

Page 17: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Dramatic improvement in drug therapy for HTN has raised the threshold for intervention in renovascular HTN

•Has led to older age at presentation and duration of HTN

•Functional significance of fibrodysplasia is more challenging since these older patients have higher incidence of essential HTN, atherosclerotic disease

Page 18: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Screening Tests

•Most commonly used screening studies:

•Renal duplex u/s

•MRA

•Radionuclide scan (Renal scintigraphic captopril test)

•Captopril: efferent arteriolar vasodilation reduces driving pressure across glomerulus, reducing GFR

•Glomerular radionuclide tracer uptake by kidney is markedly decreased

•CTA

Page 19: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Vasbinder GB et al. Diagnostic tests for renal artery stenosis in patients suspected of having renovascular HTN: a meta-analysis. Ann Intern Med 2001; 135:401-11

•Established the superiority of CTA and MRA over other non-invasive screening tests for renovascular HTN

•98% sensitive, 94% specific

Page 20: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Once patient has been identified on the basis of clinical clues and/or use of screening studies

•Angiography is most useful test for assessing hemodynamic and functional significance of renal artery dysplastic occlusive disease

•Gold standard

Page 21: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Angiographic features to determine hemodynamic significance of dsyplastic renal artery stenosis

•Demonstration of collateral vessels (usually develops when pressure gradient across stenosis approaches 10 mmHg)

•10 mm Hg is generally accepted association with increase release of renin from JXA

Page 22: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Renin assays:

•Have been important in determining functional significance of equivocal renal artery stenoses

•Most useful in patients with medically controlled HTN and older patients with arterial fibrodysplasia and extrarenal atherosclerosis

•Younger patients with poorly controlled HTN or threatened ischemic nephropathy, dx may be made via renin profiling with the renal systemic renin index (RSRI)

Page 23: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Renal systemic renin index (RSRI): alternative calculation of each kidney’s renin secretory activity

•Subtract systemic renin activity from renal vein renin activity and dividing remainder by the systemic renin activity

•Renin hypersecretion: RSRI > 0.38

•Suppression of renin secretion by a kidney defined as RSRI < 0.24

Page 24: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Indications for Tx

•Renal vein renin ratio (RVRR): compares renin activity in venous effluent from ischemic and contralateral kidneys has not been a highly predictive test

•Not reliable largely due to bilateral disease

•Considered abnormal when > 1.48

Page 25: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Drug Therapy

•Renin-angiotensin-mediated vasoconstriction is primary mechanism of hypertension in patients with unilateral renal artery stenosis and normal contralateral kidney.

•In bilateral renal artery stenosis, renin-angiotensin-aldosterone mediated sodium retention and hypervolemia are the dominant pathophysiologic mechanisms for HTN

Page 26: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Drug Therapy

•B-blocker often first drug given (Inhibition of renin secretion by B-blockade)

•In bilateral renal artery stenoses, the addition of diuretic may be used to treat hypervolemic state in these patients

•Thiazide, Lasix

•ACE inhibitor, angiotensin II antagonist (good for LVH, heart failure, diabetic nephropathy)

•Ca channel blockers

•Clonidine

•Hydralazine

Page 27: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Drug Therapy

•Undisputed: optimizing medical therapy reduces cardiovascular morbidity

•Unclear: its role in delaying the progression of nephropathy

Page 28: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Drug Therapy

•At least three randomized controlled trials comparing medical therapy with and without angioplasty

•Van Jaarsveld BC et al. N Engl J Med 2000

•Plouin PF et al. Hypertension 1998

•Webster J et al. Scottish and Newcastle Renal Artery Stenosis Collaborative Group J Hum Hypertension 1988

•No difference in BP control or preservation of renal function

•However, in largest of these studies (Plouin et al), half crossed over to receive angioplasty for poorly controlled BP within 3 months

Page 29: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

PTRA

•Percutaneous transluminal renal angioplasty (PTRA) has become the dominant mode of tx of renal arterial dysplasia at most institutions

•Angioplasty deemed technically successful when preexisting pressure gradients across stenosis are abolished

•Anatomic documentation of an adequate dilatation

Page 30: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

PTRA

•The majority of fibrodysplastic lesions may be treated with PTRA alone

•Stent placement is reserved for rescue in failed PTRA or renal artery dissection

•Mechanism of balloon angioplasty:

•Artery wall stretched, separating intima from underlying structures, splitting media, and stretching adeventitia beyond elastic recoil

•Dilated artery undergoes fibroproliferative reparative process forming neointima

Page 31: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

PTRA

•Approximately 85% of adult patients with renal artery fibrodysplasia and renovascular HTN benefit from PTRA

•Best results with patients with unilateral medial fibroplasia

Page 32: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described
Page 33: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

PTRA

•Mean overall complication rate after renal angioplasty: 11%

•Complications: dissection, perforation

•Contraindicated in associated macroaneurysms, extensive branch vessel disease, or complex dissections

•Failures correlate with longer duration of HTN and older age of patients at time of presentation for tx

•Trends in outcome after PTRA parallel those in surgical management

Page 34: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

PTRA

•Results of PTRA for renal artery fibrodysplasia in pediatric population less encouraging

•Renal artery stenosis associated with neurofibromatosis or aortic anomalies are likely to fail PTRA

•Watson et al. J Pediatr

•60% of unsuccessful angioplasties resulted in nephrectomies

Page 35: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Key: Adequate exposure

•Transverse incision (midclavicular to midaxillary on side of renal artery reconstruction)

•Midline incision

•Right-sided reconstruction:

•Expose renal artery,vein, IVC, aorta by mobilizing right colon and hepatic flexure. Kocher maneuver

Page 36: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

Page 37: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•For left-sided reconstructions:

•Reflection of viscera (mobilization of left colon)

•Exposure of left renal artery usually requires mobilization of the renal vein with ligation and transection of gonadal branch inferiorly and adrenal venous branches superiorly

Page 38: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Right sided aortorenal grafts: retrocaval position usually best

Page 39: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Left sided: grafts usually positioned beneath left renal vein

•Other sites for anastomosis: hepatic, splenic, common iliacs

•For graft-renal artery anastomosis, end-to-end anastomosis is preferred to end-to-side (spatulation of graft posteriorly and renal artery anteriorly)

•In pediatric population, interrupt sutures to allow for anastomotic growth

Page 40: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Autologous vein grafts preferred

•Autologous hypogastric artery grafts are favored bypass procedures in children

•Dacron, PTFE grafts

Page 41: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•For proximal segmental disease pattern, there are three methods of repair:

•Separate implantations of renal arteries into single conduit

•In situ anastomosis of involved renal arteries in side-to-side manner to form common orifice

Page 42: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Remimplantation of an affected artery beyond its diseased segment into adjacent normal artery (end-to-side)

•Ex vivo repairs:

•Require mobilization of entire kidney including accompanying vasculature and ureter to the pelvis

•Renal artery vein transected

•Tourniquet around intact ureter to prevent collateral blood flow

Page 43: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Cold LR to flush kidney of venous effluent

•Kidney connected to perfusion mannifold

•Hypothermic perfusion begun

•Dissection of renal artery to level of visible/palpable disease

•Iliac artery arterial autograft flushed

•Sequential branch anastomoses in end-to-end fashion over metal dilator to prevent narrowing

Page 44: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Perfusion cannulas removed, kidney repositioned in retroperitoneum

•Proximal aortic anastomosis, renal vein anastomosis completed

•In situ repairs:

•Appropriate when patient has 2 kidneys requiring primary repair limited to first bifurcation

Page 45: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Ex vivo repairs:

•Reoperation for failed prior renal arterial repairs

•Multiple branch artery lesions in single kidney

•Extension of branch vessel disease into renal hilum

•Certain branch artery stenoses in children

•Traumatic injuries involving the renal hilum

•Stenoses involving multiple renal arteries

Page 46: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Alternative reconstructions:

•Splenorenal bypass (left-sided); must document normal celiac artery

•Should not be done in pediatric patients

•Complex reconstructions:

•Operative tx of fibrodysplastic renovascular HTN in face of aortic hypoplasia or corarctation

•Thorocoabdominal bypasses and local aortoplasties with concomitant renal artery construction

•Operative mortality 8%, 90% of survivors benefit

Page 47: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described
Page 48: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Incidence of early postoperative aortorenal vein graft thrombosis: 2-7%

•Occurs less often with arterial autografts

•More common in small-diameter arteries and branch vessel reconstructions

•Study of choice to r/o early postoperative graft occlusion: arteriography

Page 49: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Late vein graft stenoses: 8%

•Intimal hyperplasia

•Clamp injury

•Traumatic dilator advancement•Marked aneurysmal change in aortorenal grafts:

•2% in adults

•20% of vein grafts in pediatric population

Page 50: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•“Beneficial outcomes after operative intervention for renovascular HTN are directly proportional to the accurate identification of appropriate surgical candidates and performance of adequate reconstructive procedure”

•Cooperative Study of Renovascular HTN:

•Less than optimal results: ?errors in patient selection and early technical failures

•577 surgeries in 520 patients with all forms of renovascular HTN

•51% cure, 15% improvement, 34% failure

•Renal artery fibrodysplasia more responsive than for atherosclerotic disease

Page 51: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Results for surgical tx of renal artery fibrodysplasia for control of arterial HTN good

Page 52: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

Page 53: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Surgical Therapy

•Change in clinical profile over the years:

•Older age at presentation

•Longer duration of HTN

•Higher prevalence of extrarenal atherosclerosis

Page 54: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Conclusions

•Renovascular HTN should be excluded in young patients presenting with HTN and older patients with resistant HTN, acute renal dysfunction induced by ACE inhibitors, or unexplained episodes of flash pulmonary edema

•Arterial fibrodysplasia as a cause for renovascular HTN is uncommon relative to atherosclerotic disease as a cause for renovascular HTN

•Etiology unknown

Page 55: Arterial Fibrodysplasia Encompasses a heterogenous group of arterial dysplastic lesions affecting small and medium-sized arteries Unknown etiology Described

Conclusions

•PTRA is most successful in renal artery fibrodysplasia in adults

•Less successful in children and for atherosclerotic disease

•PTRA and surgical revascularization for renal artery fibrodysplasia comparable

•A large randomized trial evaluating best medical therapy with and without revascularization using endpoints of BP control, renal outcome and cardiovascular mortality is needed