unit 2- renal vascular

the main renal arteries arise

laterally off AO and distal to SMA

the RRA is longer and

courses posterior to IVC

the LRC is longer and

courses anterior to AO

the main RA's divide into multiple branches as they enter the kidney and supply blood to (3)

kidney, adrenals, ureters

segmental arteries

divide into multiple branches as the enter the hilum

interlobar arteries

divide between the renal pyramids and penetrate renal parenchyma

arcuate arteries

run parallel to renal cortex and become interlobular arterioles

main renal arteries from prox to distal

segmental, interlobar, arcuate

renal parenchyma

actual functional tissue of the kidney

renal intraparenchymal

located within or inside the functional tissue

each RV is formed from

tributaries that join at the renal hilum

renal veins are best seen in

transverse, RV being anterior to RA

Accessory renal arteries (multiples)

12-22% of patients, left being more common, may arise from AO below or above main renal arteries, may also arise from SMA or illiac arteries, may pass anterior to the IVC

what percent of patients have the L renal vein go behind the AO

2-5%

approximately 10 million people with

uncontrolled HTN is caused by chronic kidney disease, renal artery disease, renovascular hypertension

renovascular hypertension etiologies

atherosclerosis, fmd, aorta disease and others such as aneurysms and extrinsic compression

atherosclerosis is the

most common cause with proximal RA being more common, more common in men than women, typically older and bilateral lesions in over 30% of patients

FMD is

string of beads appearance,segmental narrowing and dilation, mid to distal RA (bilaterally), more common in women than men, 25-50 y/o,

aorta disease is

aortic dissections continuing into the RA's or aortic coarctation proximal to the RA's

decreased renal function can lead to

azotemia, unexplained venous insufficiency, pulmonary edema and hypertensive children

decreased renal function can lead to what sound

abdominal bruit

for a renal doppler exam, patients should be NPO for

8-12 hours

what is the primary diagnostic tool for diagnosing renovascular hypertenion

duplex ultrasound

what is MRA and CTA is used for for diagnosis

secondary confirmation

what is the direct method for renal doppler exams

evaluated entire renal artery from AO to renal parenchyma with dopplers obtained at orgin, prox, mid, distal and hilum

what is the indirect method for renal doppler exams

evluated segmental, interlobar and arcuate arteries at superior, mid and inferior poles with a total of 9 doppler waveforms. Any abnormalities associated with RA stenosis or occlusion

what is the phrase to remember the difference between the methods for exams

direct is blood from into the kidneys, indirect is the blood flow within the kidneys

Within the direct protocol you must obtain

all 5 but you NEED at least 3

what will you measure on the waveforms with the direct method

PSV, EDV and AT

what is a major landmark within the direct protocol

left renal vein, your entire image should look like a spider

within the direct protocol, what is the normal range for the renal artery

low resistive, PSV should be 100 +/- 20 cm/s and EDV at 30 +/- 5 cm/s

direct method technical limitations

high failure rate, accessory renal arteries, poor doppler angles, long exam times and requires a very skilled sonographer

what is the indirect method protocol

transverse sweep (superior to inferior) and measure in longitudinal 3 TIMES

comparing side of the kidney there should only be <__ difference between R and L

2 cm

what are the normal values of kidney measurements

length: 8-13, width: 5-7, decreases with age

indirect spectral doppler changes

lowest velocity scale, small sample volume, wall filter low

what do we measure on an indirect protocol waveform

PSV, EDV, AT, and RRI

accuracy of the indirect method improves when

MRA is >80% stenosis

normal renal waveforms

presence of ESP, AT: <0.07 s, RRI <0.7 and low resistance flow

criteria for >60% stenosis (abnormal waveform)

loss of ESP, AT: >0.07s, flattened systolic upslope, tardus parvus waveform, reduced flow within kidney

tardus parvus waveform

A specific Doppler ultrasound pattern seen in arteries that are distal to a significant narrowing or blockage. Has a slow, wide and weak peak

RRI value normal

<0.7

RRI value boarderline

0.7-0.8

RRI value increased

>0.8

the lower the RRI

the more healthy the kidney is

the higher RRi

the more restricted blood flow

formula for RAR

renal artery PSV/Aorta PSV

criteria for RAR

<3.5 = 0-59% stenosis

>3.5 = 60-99% stenosis

PSV > 150 cm/sec may be consistant with > 80% stenosis

PSV >200 cm/sec with post stenotic turbulence = 60-99%

<60% stenosis

•PSV <180cm/sec, no post-stenotic turbulence, RAR <3.5

•PSV <180-200cm/sec, possible post-stenotic turbulence, RAR 2-3.5

>60% stenosis

•PSV >180cm/sec, post-stenotic turbulence, RAR >3.5

•PSV >180-200cm/sec, post-stenotic turbulence; RAR >3.5

the indirect method should be used ___ __________ _____ the direct method

in conjuction with

IF RI IS HIGH ON YOUR INDIRECT YOU NEED TO

ASSESS THE RENAL ARTERIES!!

renal artery occlusion

now flow in a well visualized MRA, low amplitude, low flow within parenchymal vessels and small kidney size (less than 9cm)

renal vein thrombosis (acute)

pain and hematuria (blood in the urine)

renal vein thrombosis (chronic)

asymptomatic, hematuria, renal failure

causes of renal vein thrombosis

intraluminal tumar, thrombosis, extrinsic compression

renal vein thrombosis is associated with

pre-existing renal disease, trauma, dehydration, renal cell carcinoma

acute rv occlusion ultrasound findings

enlarged kidney, parenchymal echogenicity changes, RV becomes enlarged, absent color and spectral doppler signals

Allograft

any tissue transplanted from one human to another

renal transplant sonographic evaluation

baseline within 48 hours: renal size, hydrophrosis, external fluid collection, rejection

hydropnephrosis

swelling in one or both kidneys, or transplanted kidney cause by a buildup of urine

renal transplant rejection patterns (5)

enlargement and decrease echos in pyramids, hyperechogenic cortex, localized area of renal parenchyma with anechoic area in polar areas, distortion of renal outline, patchy sonolucent areas in cortex and medulla

renal transplant vascular complications

arterial stenosis, arterial occlusion, AV fistula and pseudoaneurysm

post renal transplant arterial stenosis occurs:

most common vascular complication of renal transplants (12%) and lesion within 1 cm of the anastomsis

doppler in post renal transplant arterial stenosis

increased spectral broadening, post-sten turbulence, dampened waveforms distally, decreased AT

clinical findings in post renal transplant arterial stenosis

rise in creatine, htn, bruit over graft

treatment for post renal transplant arterial stenosis

angioplasty

kidney stones

hard pebble-like deposits of minerals and salts that form in your kidneys

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