surgery, procedures, QA, physics

ICA endar stenosis after >1yr is bc…

atherosclerotic disease

NASCET angiographic ICA stenosis calculation

%ICA stenosis = (1-[narrowest ICA d/normal distal cervical ICA d])x100

%ICA stenosis = (1-[d/D])x100

Reynolds # equation

Reynolds # = (average flow speed x tube d x density)/viscosity

# of crystals in CW doppler

2

how to increase sensitivity & accuracy

increase packet size (ensemble length)

• # of pulses per scan line

magnitude & direction describe…

velocity

FFT

spectral analysis (PW)

• convert frequency shift into spectral waveform

• display ALL frequencies

**zero analog (CW)

rayleigh scattering

soundwave hits structure smaller than wavelength

frequency^4

reflector (RBC) velocity equation

propagation speed x doppler freq shift / (2 x operating freq)

range resolution

ability to determine depth of reflector by timing how long it takes for sound to go transducer-reflector-transducer

only in PW

autocorrelation

estimate V in color flow imaging

bidirectional flow

detect blood flow toward & away from transducer

normal dialysis flow volume in outflow veins

increased flow volume

endoleak types after AAA EVAR

type I: incomplete seal at ends

type II: sac fill via branch vessel (retrograde)

type III: stent defect/tear

type IV: porous graft

type V: AAA expansion w/out leak site

mc type of endoleak AAA EVAR

type II

• sac filling via branch vessel (retrograde)

renal transplant rejection S&S

high serum creatinine

100+ degree fever

‘flu-like’

tender kidney

swelling

low urine output

mc anastomoses for kidney transplant

renal artery-EIA

mc post-op renal transplant complication

lymphocele formation

• 2-6M post-op

TIPS

create shunt btwn PV & HV

• treat portal HTN

• normal V: 120cm/s

segmental P can not be correlated w…

MRI

mc treatment for single-level disease found w segmental P

angioplasty (balloon) or stent

spectral broadening

increased bandwidth bc turbulence

vertical thickening during systole

seen at…

• high flow V

• vessel branching

• small d

needle becomes more visible during US when…

heel-toe to increases incidence angle

• optimal angle is 90 degrees

“low flow” in insitu venous bypass that predicts early failure

PSV<40cm/s

insitu bypass graft stenosis at vein valve

PSV>180cm/s & ratio>2.5

*should do repeat valve lysis

remaining graft branches at AV fistula should be fixed by…

ligation

mc peripheral artery intervention failure <1yr old

myointimal hyperplasia

surveillance of peripheral bypass graft or EVAR is initiated w/in…

1M

surveillance of CEA or stent-angio is initiated w/in…

2-3M

bypass/graft procedure most likely to result in problems (AV fistula, retained valves)

in-situ saphenous vein bypass

• leave vein in place, lysis valves, ligate branches, attach ends to native arteries

in fem pop reversed vein graft which anastomosis has highest velocity?

fem a & smaller vein end

• bc goes large fem a to small vein

kissing stents

treat aortoiliac occlusion (AO BIF or prox CIA)

2 stents deployed…1 in each iliac a w prox end of stent ‘kissing’ AO

when to use fem-fem bypass?

occluded unilateral ilac a

3 mc AV fistulas

radiocephalic, brachiocephalic, brachiobaslic

*start as far distal as possible

early graft failure bc…

1M-1yr graft failure bc…

>1yr graft failure bc…

technical error

intimal hyperplasia

atherosclerotic disease

inflow artery flow prox to AV fistula has…

high diastolic flow

• bc flow from high P artery to low P vein

significant stenosis w hyperpulsatile AVF & arm edema is bc…

radialcephalic outflow stenosis

physical sign dialysis fistula central stenosis

edema

normal radial a waveform peripheral to AVF

multiphasic & antegrade

normal afferent a (towards) flow prox to AVF

high diastolic flow

• bc flow high P artery to low P vein

characteristics when AFV is mature & ready for hemodialysis

flow volume: >600mL/min

draining vein d: >6mm

skin-vein distance: <6mm

brescia-cimino fistula

mc AVF

• radiocephalic @wrist

**common place for cephalic stenosis is at cephalic arch over shoulder

significant ABI improvement 3M post-op

ABI increase >0.15

leading cause of mature fistula failure

thrombosis

sclerotherapy treats…

spider veins

when to use IVC filter

prevent PE in patients w DVT w contraindication for anticoagulants

sensitivity

ability to correctly identify disease

• true positive

specificity

ability to correctly identify no disease

• true negative

after endarterectomy, ICA may be…

wider w stitches visible

stenosis development >1yr post-op likely bc…

atherosclerotic disease

resistance equation

poiseuilles law

how much fluid is moving thru vessel

• ONLY straight, rigid tube

*Q=P/R

reynolds number equation

types of energy

potential: stored up energy

kinetic: motion & work

hydrostatic: gravitational

bernoulli equation

says, “total energy along streamline is constant”

quantifies doppler

V & P are inversely related

*in stenosis…V is high & P is low (r is low & Q is low)

area reduction will cause…

V increase (V & r inversely related)

distal P decrease

prox to stenosis…

diastolic flow reversal disappears & becomes monophasic

• bc increased R

arterial symptoms vs venous symptoms

radial a vs GSV for CABG

radial artery pros

• appropriate vessel caliber

• thicker walls, less hyperplasia

• more available

radial artery cons

• incomplete palmar arch

AO-bifem graft

AO to distal iliac or CFA (bilaterally)

to bypass distal AO

to bypass iliac artery disease mc

fem-fem ‘jump’ graft

bypass 1 iliac artery stenosis/occlusion

1 iliac artery supplies both legs

axillo-fem graft

axillary artery to distal EIA or CFA

bypass severe AO disease

in situ vein graft

CFA to distal PTA

bypass fem-pop occlusion

*use GSV & remove valves; cut perforators

*connect prox v to CFA & distal v to PTA

reversed vein graft

CFA to distal PTA

bypass fem-pop occlusion

*remove GSV & flip upside down; cut perforators

*connect prox v to CFA & distal v to PTA

• vein small end to artery large end

***V decreases distally bc diameter increases

PTFE grafts

contains air

‘christmas’ lights

EVAR

repairs AAA w stent graft thru groin-to-AO

hemodialysis fistula vs graft

fistula:

• most effective

• must mature

graft:

• synthetic tube for small veins

• more likely to infect/clot

• no maturation (1 wk)

catheter:

• only use for immediate access

hemodialysis fistulas

radial a - cephalic v (wrist)

brachial a - cephalic v (AC)

brachial a - basilic v (upper)

doppler equation

big or small drop in P from AO to distal arteries?

small P drop

• so low resistance

prox to stenosis

triphasic

plug flow

high resistance

w/in stenosis

high V

low P

distal to stenosis

dampened pattern & delayed upstroke

no pulsatility

no triphasic & low resistance

turbulence; flow reversal & eddies

spectral broadening

Wells criteria estimates probability of…

PE

how much more likely is DVT than PE?

3x

low systolic flow V (28cm/s) in graft means…

graft thrombosis

**low V & low volume increase thrombosis risk

percutaneous transluminal angioplasty PTA

treat narrow LE vessels

puncture FA & stretch open w balloon

surgery to remove plaque in vessel

*more invasive than PTA