Chap 144-148 Renal Artery Stenosis/Aneurysm Flashcards
What is the natural hx of RAS?
3 years
about 8% of normal and 40% subcritical blockage progress to >60% stenosis
7% of >60% progressed to occluded
> 60% will have decline in renal function, decrease renal size
10% progress to dialysis in 4 years
How many patients have bilateral RAS? Have complete occlusion?
12%
12%
What factors are associated with progression?
age, high SBP, smoking, female, poorly controlled HTN
What is the pathogenesis of RAS?
athero 80%
FMD 15%
dissection 1%
How dose RAS cause HTN?
renal blood flow reduced, juxtaglomerular cells convert prorenin into renin and secrete into circulation.
renin converts angiotensinogen to angiotensin I then to angiotensis II by ACE.
AII causes blood vessel constriction and HTN. also secretes aldosterone which causes renal tubules to reabsorb NA and water into the blood (volume expansion).
What are the clinical presentations of RAS?
50% have no symptoms
ARF when starting ACEi if bilat RAS
HTN crisis
flash pulmonary edema
What blood work can support RAS?
urea and cr may be elevated
strain pattern on EKG
LVH
elevated plasmin renin
What findings on duplex can support RAS?
critical stenosis = peak systolic velocity in main RA >1.8-2.9 m/sec with post stenotic turbulence >60%
ratio renal artery to aortic peak systolic >3.5 =60%
blunted waveforms with delayed systolic upstroke are indicative of a proximal stenosis
acceleration time >100msec indicates critical stenosis within prox renal artery
resistive index
peak sys gel-end diastolic velocity/peak sys vel
>0.8 may be critical RAS
what is medical management in RAS?
ACEi-first line/ARB
then CCB/BB
statin (decrease risk of progression)
RF modification
What are indications for revascularization if RAS asymptomatic? (AHA)
IIb percutaneous
if bilat or solitary kidney and hemo signify RAS
What are indications for revasc in HTN? (AHA)
IIa
perc
hemo signif RAS, accelerated HTN, resistant HTN, malignant HTN, unexplained unilateral kidney and HTN with med intolerance
What are indications for revasc in renal dysfunction? (AHA)
IIa
progressive kidney disease and bilat or solitary kidney
IIB
chronic renal insuff and unilat RAS
What are indications for revasc in CHF/angina? (AHA)
I
percutaneous with RAS and recurrent unexplained CHF or sudden unexplained pulmonary edema
IIA
RAS and unstable angina
What do you consider open surgery?
not amenable to endovascular
early branching, segmental arteries
patient needs pararenal reconstruction
failed endo esp FMD
During open bypass what adjuncts can be administered/done to protect kidney?
mannitol 12.5 mg early in operation
repeat dose before and after ischemia 1g/kg
mannitol increase GFR and renal plasma flow without increase in blood volume
intermittent perfusion
cold perfusate
slush/ice
Who benefits most from interventions?
with rapid decline in prep GFR with severe bilat RAS and severe HTN
During open bypass what adjuncts can be administered/done to protect kidney?
mannitol 12.5 mg early in operation
repeat dose before and after schema 1g/kg
mannitol increase GFR and renal plasma flow without increase in blood volume
intermittent perfusion
cold perfusate
slush/ice
what is treatment for renal vein thrombosis? when to consider sx?
3-6 months of anticoagulation
thrombectomy reserved for bilat thrombosis, PE, single kidney, caval thrombosis, ARF, persistent serve symptoms, CI to AC
What are result for open repair for RAS?
patency for bypass at 3 years 97% 85% improvement of HTN (variable) 3.3% re-stenosis declinig renal function 4% morbidity 10-20% mortality 5% 70% removed from dialysis
For acute renal ischemia, how long before irreversible ischemia?
1 hour 70-80% can recover with weeks
3-4 hours irreversible
What are consequences of thromboses renal vein?
acute renal ischemia from
congestion and edema
what are the symptoms of renal vein thrombosis?
capsular distention leading to pain
triad, flank pain, hematuria, thrombocytopenia (13%)
what is treatment for renal vein thrombosis? when to consider sx?
3-6 months of anticoagulation
thrombectomy reserved for bilat thrombosis, PE, single kidney, cabal thrombosis, ARF, persistent serve symptoms, CI to AC
What is treatment for RA embolism or thrombosis?
AC alone unless bilat or solitary kidney
What are the results of AC for RA thrombosis? for OR?
1 month mort 10%
60% normal renal function at long-ten follow-up
8% required dialysis
25% mortality with open
What is middle aortic syndrome?
coarctation of the abdominal aorta
What causes middle aortic syndrome?
over fusion of the two dorsal aortas during 4th week of gestation
What disease associated with MAS?
NF-1 williams syndrom maternal rubella takayasu umbilical artery catheterization
What stenosis are associated with MAS?
splanchnic 90%
RA 60%
usually ostial
What are clinical features of MAS?
HTN (HA, seizure, AKI, bell's palsy,) lower extremity fatigue (uncommon) FTT intestinal angina LVH, flash PE,
What is the definition of HTN in children?
SBP or DBP >95th percentile for sex age and hgt
What is management of MAS?
anti htn
patch angioplasty
reimplant viscerals
thoracoabdominal bypass
What sized graft to use for TA bypass for children, adolescents and adults?
8-12mm children
12-16 early adolescents
14-20 late adol, adults
whats the repp rate at 5-10years?
10%
axial growth not significant after10 yo
What is the usual appearance/location of RA aneurysms?
true
90% extraparenchymal
75% saccular
usually at main renal artery bifurcation
What are causes of RAA?
FMD EDS dissections iatrogenic trauma post-stenotic dilation polyarteritis nodosa (intrarenal)
what is presentation of RAA?
asympto
1/3 with symptoms
HTN, flank pain, hematuria, rupture
RI with distal emboli or compression
What are indications for intervention?
>2-3cm rupture (10% mortality) consider if pregnant HTN---DBP >90 despite 3 anti-HTN Dissection if viability threatened
What is mortality and patency of open repair?
1.7%
96% 4 year patency
What are components of cold perfusion preservation solution?
KCL, NA, phosphate, Bicarb, chloride
what is polyarteritis nodosa?
medium sized arterial vessel vasculopathy that cause small aneurysms that are strung like beads (rosary sign)
tx cyclophosphamide and steroids
What is the presentation of renal AVM?
hematuria (70%) HTN RI high output CHF, rupture vague abdo/flank pain
Which more common r or l?
right
what are causes of renal AVM?
congenital acquired (biopsy 1-10% incidence, trauma, iaotro) FMD aneurysm/malignancy erosion nephrectomy
What is appearance of renal AVM on CT?
filling defect in kidney with dilated vessels
When to tx? and what tx?
after bx most close spon within one year
most don’t require tx
consider if HTN
What is difference in pathophys in bilateral and unilateral RAS and RV-HTN?
Juxtaglomerular cells release rennin—angiotensinogen to AI, ACE then cleaves to AII.
AII causes vasoconctriction and stimulates reabsorption of NA and H2O
Angio recep type I activation leads to hyperplastic remodeling of wall of periph arteries and arterioles
AII promotes volume expansion by activating ATR1 on renal tubules wo increase NA reabs and stimulating release of aldosterone (promotes renal tubular NA reabsorp)
In paient with one functional kidney, this volume expansion can be blunted
In bilat RAS or solitary kidney cannot compensate and result in Goldblatt volume dependent HTN
what are clinical characteristics of RV-HTN?
Bilat RAS may present with acute RF with ACEi trial (increased efferent arteriolar tone from AII critical compensation mechanism to maintain filtration pressure)
Flash pulmonary edema/CHF
Recalcitrant HTN previously well controlled
Slowly increasing serum
cr levels
Unprovoked hypoK
Abrupt onset of HTN
list causes of RV-HTN. which are 3 most common?
RAS
FMD
dissection
Takayasu (sub-continent and far east
hypoplastic/MAS in children Emboli Trauma Ligation during surgery Extrinsic compression
How does captorpil renogram work? what abnormal/normal rest?
Captopril ACEi
In reduced perfusion, kidney respond with efferent arteriole constriction caused by AII. If this is blocked then decline in renal function due to loss of compensatory efferent arteriolar contriction.
If contra kidney normal will show enhanced excretory functio after ACEi and efferent arteriolar dilation leads to increase GFR in setting of normal perfusion.
What are signs/symptoms of RV-HTN?
Bilat RAS may present with acute RF with ACEi trial (increased efferent arteriolar tone from AII critical compensation mechanism to maintain filtration pressure)
Flash pulmonary edema/CHF
Recalcitrant HTN previously well controlled
Slowly increasing serum cr levels
Abdominal bruit
What are RF for contrast-induced nephrotoxicity?
Age CKD Diabetes mellitus Hypertension Metabolic syndrome Anemia Multiple myeloma Hypoalbuminemia Renal transplant Hypovolemia and decreased effective circulating volumes Urgent Volume of contrast
Define resistive index?
how do yo calculate?
What are normal values?
Sonographic index used to asses for renal arterial disease
(Peak systolic velocity-end diastolic velocity)/peak systolic velocity
Normal 0.7
>0.8 may be critical RAS but not specific for stenosis
What are the mechanisms by which AII causes HTN?
vasoconstriction
increase renal tubular cell absorption of sodium
release of aldosterone which promotes renal tubular sodium absorption
acts on nuclei of the brain responsible for BP regulation (stimulates thirst)
What are the effects on the unaffected kidney in RAS?
exposure to sustained HTN and circulating ATII and aldosterone
efferent and afferent arteriolar vasoc
sustained decrease in glomerular filtration
afferent arteriolar hypertrophy and arteriosclerosis
How does renal vein renin assays work?
stop antiHTN
give lasix night before
catheter in each renal vein and one in IVC
reference sample then samples q5mins x2
What are abnormal values for renal vein renin assay?
renal vein to systemic ration
>1.5 is positive
What is the difference in stenting vs surgery for RAS
MA
BP control equivalent
Who to treat for RAS?
uni-if severe HTN and low risk
bilat but one kidney sever-treat like uni disease
bilat severe-htn severe and renal dysfunction
What are open techniques for RAS?
aorto renal bypass
thromboendarterrectomy
renal artery reimplantation
hepatorenal bypass
splenorenal bypass
ex vivo reconstruction
What are the results of the CORAL trial?
stenting showed no benefit over PMT in reducing death or MACE in RAS
STAR and ASTRAL trial demonstrated the same
What are components of cold perfusion preservation solution?
K sodium phosphate chloride bicarb
What is a cortical rim sign?
on CTA the cortical rim is capsular perfusion from collaterals
What are catheters that can be used to select the renals?
KMP Sos Omni C1, C2 shepherd hook simmons JB1
What are endovascular treatments for RA embolism?
CDT
aspiration
covered stent
Which RA embolism to offer intervention?
acute and potentially salvageable renal function esp. bilateral embolism
What is the mortality of surgical management for RA embolism?
25%
How is the management of RA thrombosis different to Renal artery embolism?
Will need angioplasty and stenting
need bypass or endart
