Gretchen

A. W. Gooding,

MD

Sandra

Perez,

#{149}

RN

Joseph

H. Rapp,

#{149}

MD

William

C. Krupski,

#{149}

MD

Lower-Extremity Vascular Grafts Placed for Peripheral Vascular Disease: Prospective Evaluation with Duplex Doppler Sonography’ Eighty-five men with 92 vascular grafts placed for peripheral vascular disease of the lower extremity underwent a total of 264 examinations with duplex Doppler over a 2.5-year penod. In 64 patients who underwent more than one examination, the total follow-up encompassed 740 months. In 220 native femoral arteries (96.0%) the peak systolic velocity (PSV) was higher than that in the graft. Arteriovenous shunting was associated with a normal PSV and a markedly elevated diastolic component at spectral analysis. Focal fluid collections were common initially near the graft and usually disappeared uneventfully. An average PSV of 32 cm/sec or less was always associated with impending occlusion. The sensitivity of an average PSV of 40 cm/sec or less to indicate impending graft occlusion by the next visit was only 33%; the specificity, 94%. At initial examination, stenoses were associated with high PSV focally in the graft or low PSv with absent diastolic flow. Index

terms:

Arteries,

teries, grafts and Arteries, stenosis teries, US studies,

supply,

92.7214

femoral,

prostheses,

or obstruction, 92.12984

92.7214

92.45,

#{149} Ar-

92.7214

92.7214 #{149}ArExtremities, blood (US), Doppler

#{149}

Ultrasound

#{149}

T

advent

HE

lows

of more

(US)

definition

of both

astolic

forward

flow

tients

who

had

of a vascular cular disease

pler

unit

(SPA

Calif). Their years

1000;

(average

age,

study

after

and

surgery.

Of the

85 patients underwent

the initial

Received

requested ceived

March

dress

reprint

C

November

February

RSNA,

29, 1989;

revision

20, 1990; final revision

25, 1991;

accepted

requests

to G.A.W.G.

1991

from April

April

re-

1. Ad-

one.

6 weeks, during

3

21

92

264

3 months,

6

what

actu-

64 pa-

examinations

than

In these

64 patients, the encompassed 740 months

total follow-up (average follow-up per graft, 11.6 months). The range of follow-up in these 64 patients

was

2 days

Imaging tient distal

the native

(with

at

the dorsalis

pedis

of these

specffic

were

performed:

artery.

levels,

seven

1. An image of the graft was generated. 2. A measurement of peak systolic velocity (PSV) in centimeters per second was obtained from this image. 3. A measurement of time-average yelodty (TAV) was also obtained from this image. The TAV measurement was generated with the range gate opened the width of the vessel on longitudinal scan. With range-gated black-and-white duplex which

was

used

in this

study,

abnormal sites of altered flow dynamics can be detected only by actual sampling of the flow velocity with analysis of the spectral data. It is possible that focal stenosis or other abnormalities were present but undetected in areas of the graft not specifically examined. Color-coded Doppler would changes

eliminate in color

this deficiency because indicate significant ab-

normalities in velocity or direction visually (3). The angle of insonation was 40.-60.

the pa-

vessel

to the

at specific areas along The graft was visualized its course with sonography,

anastomosis

the graft. throughout

from

and spectral only at desigfemoral artery;

to 27 months.

was performed

supine)

36

examination

was

Doppler,

to undergo

in Table 1. with 92 grafts,

more

1987 study,

the second

However,

is seen

imag-

lower-extrem-

patients

tients

of Radiology

7

calculations

separate

prospective

1 week,

Studies 23 42 60 52 30

At each

Milpitas,

grafts were performed to October 1989. In this

1 year,

Total No. of

the proximal, middle, and distal thigh; at the popliteal fossa; and, in more distal grafts, at the proximal, middle, and distal calf and at the anastomosis, which most

69.2 years).

in the

with

23 21 20 13 6 6

analysis were performed nated sites: at the native

from 56 to 92

of 92 peripheral

ally occurred

94121.

Diasonics,

sixty-four

enrolled

Graft

1 2 3 4 5 6

but Doppler

METHODS

ages ranged

No. of Graft Examinations

Total

Eighty-five men with peripheral grafts of the lower extremity underwent examination with a high-resolution (10-MHz imaging, 4.5-MHz Doppler) duplex Dop-

year

Departments

No. of US Studies

distally

months,

the

Infrainguinal

placement

AND

and in 85 Patients Grafts

a prognostic

ity

(G.A.W.G.) and Surgery (S.P., J.H.R., W.C.K.), San Francisco Veterans Administration Medical Center, 4150 Clement St. San Francisco, CA

of US Studies

Examinations

graft for peripheral vasof the lower extremity.

examination

From

are

1

Number

morphol-

undergone

PATIENTS

ing studies

180:379-386

the

Table

al-

indicator of poor graft survival (1,2). Our study prospectively examined the utility of duplex US to determine morphology and flow characteristics of 92 infrainguinal grafts in 85 pa-

Two hundred 1991;

technology

ogy and dynamics of flow in arteries and veins. The utility of this technology in the surveillance of infrainguinal vascular grafts placed for the treatment of peripheral vascular disease is a subject of great interest that holds promise in the delineation and detection of abnormal flow patterns to predict impending graft failure. Bandyk et al have shown that low graft blood velocities with absent di-

studies Radiology

sophisticated

ultrasound

Abbreviations: peak systolic

AV velocity,

=

arteriovenous, PSV = TAV = time-average ye-

locity.

379

Table 2 Average Values Value

of All Patent PSV

TAV

(crn/sec)

(cm/sec)

(cm)

(mL/min)

74.8

18.2 3-89

.48 .3-.8

175.6 23-646

Mean Range

34-118

Table 3 Average Values Figure 1. A longitudinal mal triphasic distal thigh

sonogram of a norsegment of graft

demonstrates a TAV measurement. The markers are on an initial peak systole and final peak systole. The range gate is open the entire vessel. DTG = distal thigh graft.

of G rafts

Diameter

0 cclusions

with

TAV

PSV

a to

Grafts

Value

(cm/sec)

(cm/sec)

Mean Range

61.4 21.7-120

9.4 2.3-27.7

this

diameter,

milliliters calculation

[cubic

a flow

measurement

was on

calculated. the formula:

per minute was based

centimeters

velocity

per

[centimeters

second] per

second]

(This flow

of arterial 6. Then

lumen [square the technologist

centimeters]).

cumference

of the graft

on a transverse

scan, and an area of the graft ously

defined

7. The

levels

machine

per minute)

liters

images

were

was

each

and on the the machine

flow

locity require

(Fig 1). TAV the range

compass

the

that the parabolic central

under and

adjacent

cluded.

The

of both

lower

to the

following

Germany) (n = 28); (n = 47);

wall

A specific diastole, but

whether present base, systolic

(millimeters

per

value was a notation

a diastolic or absent, or (c) elevated

en-

so

are

in-

was

used:

minute)

component compared

(4).

subject

to many

tamed to determine had any relevance

but

ours

The

same and

every

380

obtained

case

The in the

technician

did

Radiology

femoroanterior femoroposterior

Putzbrunn,

Area Flow (mL/min)

.22 .12-39

145.9 10-312

in situ

During

the

tients died unavailable

ob-

all the examiperiod. performed femo-

61-80

81100

1o2o1214:

PSV (in centimeters

per

second; values shown at bottom) in grafts that were occluded by the time of the subsequent examination (diagonal bars) (20 examinations) compared with average PSV in patent grafts (black bars) (233 examinations). In a total of 264 graft examinations, PSV was

in two examinations;

no PSV

was calculated and a 2#{176} occlusion was noted in nine examinations; grafts were patent in 233 examinations; and in 20 examinations, occlusion was shown in the next study.

tibial in situ tibial, reversed

saphenous pedis

in

phy,

grafts.

36 grafts;

in

study,

17 of the 85 pa-

(20%) and follow-up was in five patients. Thirty-

two graft examinations formed in those who

were perdied, 11 in the

five

follow-up;

patients

patient

was

without

lost

to follow-up

after

six

examinations over 1.5 years. At the conclusion of the study, 51 grafts were functioning (55%), 21 had occlusion (23%), and six had been re-

done

(6%).

performed

Thrombectomy in eight

grafts;

had angiogra-

been

angioplasty,

eight

This

grafts in which angioplasty had been performed. Of the eight grafts that required thrombectomy, seven continued to function; occlusion occurred

other.

Of the

six grafts

occlusion

that

occurred

had in

four, and two continued to function. In 230 of a possible 253 femoral arteries, the mean PSV was 124 cm/sec. Psv was not calculated in 23 femoral arteries wound,

one

and

left 50 patients with 51 grafts. At the end of the study, occlusion had occurred in all but two of the

in the

RESULTS

are

were

measurements

over a 30-45-minute 264 examinations were following types of grafts:

#{149}

polytetrafluoroethylene

41-60

Average

not calculated 28);

=

(n = 4); femoroposterior tibial, vein (n = 1); femoroposterior ribial in situ (n = 38); femoroperoneal in situ (n = 27); femoroperoneal, reversed saphenous (n = 3); femorodorsalis pedis, reversed saphenous (n = 6); femorodorsalis pedis in situ (n = 57); popliteal-posterior tibial, reversed saphenous (n = 3); popli-

the the

whether or not they to the diagnosis of graft

the

(n

21-40

3.

to be redone,

failure. nations

saphenous

Gore & Associates, (n = 14); femoropopliteal

was (a) or below with

in this study, errors,

of

for as to

measurements of graft obtained as meticulously

as the measurements

were ocat the top

of examinations.

teal-dorsalis pedis, reversed (n = 5); and popliteal-dorsalis situ (ti = 3).

component.

Such calculated flow, even those

PSV

cephalic

higher

not recorded was made

(b) above

Area (cm2)

saphenous

peripheral

formula

reversed

(Gore-Tex;

=

flow

nine grafts 2-7, numbers

femoropopliteal

TAV (centimeters per second) x the area of the vessel in cross section x 60 estimated

examinations

two

bar are the number

ropopliteal

from ye-

examination,

flows

velocities

velocities

systole, a mean

calculations initially gate to completely

vessel

In

-20

(in milli-

on film.

final peak calculates

132 8.7-327

Figure

grafts

measured.

A TAV is obtained from spectral analysis of a group of whole waveforms in series, with the cursor placed on the initial peak systole which

flow.

was not calculated; cluded. In Figures

cir-

on the basis of area. The

recorded

Flow

cmis#{149}c

Number of graft examinations by average PSV in the 253

that showed

the

PSV

Asr.g#{149}

Figure 2. categorized

at the previ-

calculated

157.5 26-816

S

x area

drew

(mL/min)

.18 .1-.6

(mL/min)

.5 .5

Area Flow

(cm2)

to the Last US Examination

Diameter

(cm)

Area

in

mean

=

Flow

S ubsequent

Diameter

4. A diameter of the graft at the previously defined levels was measured on a transverse image by means of a cursor placed by the technician. 5. After the computer calculated an area from

Diameter

because of occlusion, or incomplete data.

open Only

nine of 230 native femoral arteries (3.9%) had a PSV lower than that of the proximal graft. When the average of all the PSVs along the graft in the initial study was compared with the average at the last follow-up study 2 days to 27 months after imaging, the PSV fell in 168 femoral

arteries

(73.0%)

by

an

average

of

August

1991

4); femo1); femo= 4); femoropostibial in situ (n = 2); femoroperin situ (n = 1); femorodorsalis reversed saphenous (n = 1);

reversed

saphenous

ropopliteal ropopliteal

terior oneal pedis, femorodorsalis

a..

]

and (n

Area

Figure

4.

Flow

Average

In

area

flow

=

pedis

(in milliliters

per minute) in all grafts that had flow amination (n = 251). No area calculations were performed in four examinations; grafts were occluded.

Figure 6. Average diameter flow (in milliliters per minute) of all 252 grafts with flow at examination. In three examinations the di-

at exnine

ameter

was not calculated.

Nine

grafts

were

occluded.

patent

grafts.

Black

bars

examinations

=

showing patent grafts (,i = 231), diagonal bars = graft examinations performed before detection of occlusion in the next study ( n = 20). In one examination, no reading was performed because the artery was occluded at the initial study.

21 grafts,

(range,

femoral

2%-78%)

arteries

and

(27.0%)

rose

by

in 62

an

Figure 7. The distinguished basis of diameter tions of patent

Diameter

Flow

grafts

that

In

mi/mn

failed

from the patent

could

not

be

grafts on the

flow. Black bars = examinagrafts (n = 232), diagonal bars

= examinations of grafts performed before detection of occlusion in the next study (n = 20). In one examination, no reading was

performed because at the initial study.

the

artery

was

occluded

just

curred. whether revealed ure.

2 weeks

afterward,

tamed.

from

The

average

values

the last US examination

with subsequent shown in Table

erage

PSV

are

the numbers categorized

in the

grafts

an average the average

greater Graft

fined which

grafts

PSV

failure

in this

as graft

occlusion.

depicts

with

compared

group, confined

Volume

the

with

shows

that

study

de-

3, of PSV

eventually in the

this

group

particular

#{149} Number

but

0 to was

Figure

those

that

to any

180

cm/sec.

from

categories

flow

that

flow at the (77%) had

of 41-100

PSV ranged 141 cm/sec.

than

of by av-

examined

had flow. Most grafts with time of the US examination

failed patent

is not category.

2

the

nine

tamed

before

weeks

to 6 months

in four

3.

Figure 2 depicts graft examinations

for

Figure

of grafts

occlusions

in

the

before

the

grafts

occluded

subsequent

4 shows

at

these ob-

occlusion

2

later. the

average

area

examinations;

nine

grafts

were

occluded. In 168 examinations (67%), flow was 51- 200 mljmin. Figure 5 shows the relationship between grafts with flow that failed and the area flow of all the patent grafts; the group with impending graft occlusion could not be differentiated from the overall group on the basis of area flow alone. Figure

6 shows

the

average

diame-

occlusion

of oc-

In these cases, one wonders closer follow-up might have a cause for impending fail-

In patients

with

Increased

was

flow (in milliliters per minute) in all the grafts with flow at examination. No area calculations were performed

obtained

and

an

average

PSV

of

1-32 cm/sec. four graft examinations were done; all of the grafts had occlusion at the subsequent examination.

None

the time of their examination, studies were the last sonograms

of 101% (range, 1.5%-182%). Several of the grafts with a PSV that rose over time had developed marked stenosis. The average values obtained from the examinations of all the patent graft are shown in Table 2. Nine grafts were occluded at the time of the US examinations, one before any PSV values had been ob-

aver-

an occlusion after a norwas obtained, one pa-

sonography

Except

average

the

[38%]) and distal pseudoaneu(one graft [5%]). Five patients

flow

present

above

400

in 11 graft

of these

grafts

with occlusion, but ciated with increased 20%

7);

four other patients had an occlusion several months later; no indication potential failure was identified at

: the

=

in situ

or lower, and PSV was 45 cm/sec with no forward diastolic flow. Other contributing factors noted at sonography were stenosis (eight

tient

grafts with of all

(n

pedis

of these

(23.8%) had mal sonogram

between area flow

=

age PSV was 40 cm/sec in one graft the average

grafts rysm

Figure 5. Relationship flow that failed and

=

in situ

popliteal-dorsalis 1).

In seven

mI/mln

(n (n

Gore-Tex in situ (n

mL/min

examinations. was

associated

several were assodiastolic veloc-

ity, which was suspect for arteriovenous (AV) shunting. Findings in grafts with an average

PSV

of 40 cm/sec

or less are listed

in

Table 4. Only one occlusion occurred in grafts with an average PSV of 120 cm/sec or greater (Table 5). In the calculations of sensitivity,

true-positive cases were those grafts with occlusions that occurred within the criteria set forth herein. True-negative cases had no occlusion. Falsenegative cases were grafts with occlusion

that

occurred

outside

the

criteria,

and false-positive cases were grafts without occlusion but which would have been expected to have occlusion according to the previously defined criteria (average PSV of 40 cm/sec less) because they fell within the

ter flow (in milliliters per minute) of all the grafts with flow at examination; 158 grafts (63%) had flow of 51-

guidelines

200

sion occurred in 11 of these grafts (Table 6). In the 87 patients with an area flow of 1-100 mljmin, 10 occlusions occurred (Table 7).

mL/min.

Figure that failed from the diameter Failure grafts

(Figs

7, too, shows that the grafts could not be distinguished patent grafts on the basis of flow. (occlusion) occurred in 21 8, 9): femoropopliteal

of the

or

Ninety-two diameter flow

In the stenosis

the

criteria.

patients of 1-100

eight grafts had a focal

stenosis

from

that range

had

grafts

cmJsec;

with occlu-

failed, graft of PSV at

117 to 225 cm/sec;

Radiology

381

#{149}

.

Table

J.

:

-

;i/-1

4

Findings

in

Grafts

with

an

Average

PSV of4O cm/sec

or Less

,17’#{149}

Graft Occlusion Finding

at US

Present

Absent

Total

Positive

7

14

21

Negative

14

218

232

Total

21

232

253

Note-Numbers

tive predictive

value

are number ofgrafts. Sensitivity = 7/21 = 33.3%; specificity = 21&232 = 7121 = 33.3%; negative predictive value = 2181232 = 94%; accuracy

:!

/

fM

irivttir

I

PTG

94%; posi(7 + 218w

= =

233=89%. Figure MHz)

Table

nant

5

Findings

in

Grafts

an Average

with

PSV of Graft

at US

Finding

Total

were middle

proximal in one

were

six patients had been nation, months

in the

with normal

in one graft,

normal

6

247

21

232

253

at spectral

In

PSV exami-

analysis

(Figs 11, 12). In two patients, this was proved with angiography to have been caused by AV shunting and was associated with a normal PSV. Transient increase 13) after graft

in diastolic implantation

velocity had

4.76%, specificity = 227/232 = 227,247 = 91.9%, accuracy

=

value

that

has

the

communication

performed an average of 3 prior to diagnosis. One pa-

waveform

1/21

graft

in

range.

focal stenosis, at the prior

Total

5

graft,

distal

Absent 227

tient had had increased PSV at a focal stenosis in the same location on a prior visit. One patient had a focal increase in PSV with stenosis on his first visit. Seventeen patients showed focal elevation of the diastolic component of the

Occlusion

1

two grafts, and present in two or more sites in four grafts (Figs 10, 11). The PSVs proximal and distal to the stenosis

or Greater

cm/sec

(Fig spon-

97.8%,

=

seen

seen

at US. In one

tient with a femoropopliteal a pseudoaneurysm of the

patients

graft peroneal

distal

initially

to the had

had

26 of 85 patients (31%) and usually resolved completely over an average of 4.9 months (range, 0.5-12 months)

distal

All patients was increased 382

Radiology

#{149}

disease

beyond

the

graft.

in whom diastolic flow at US had an in situ

hindered

portion

US. Only

this group had a graft surgery with an open

inguinal with

area

that

US because

of the

one

was

not

graft

patient

infection wound

access

in

monly

fluid seen

collections initially

examined

was

were near

was

functioning

well.

(Figs

12c,

These

difficult.

the

corngraft

in

16).

fluid

collections

were rorna.

attributed to hematoma or seNo instance of fluid tracking along the graft was noted. The fluid collections caused no particular prob-

attributed

to edema

fluid,

after at the

In all other instances, both proximal and distal anastomoses were well seen, as were the interval areas of the graft (Figs 14, 15). Focal

is very faint on later, this graft DCG = distal calf graft.

immediately adjacent the compressing fluid. In nine patients, focal areas of decreased echogenicity in the soft tissues of the lower extremity were

an open

critical

that

saphe-

lems, except in one case in which the waveform of the graft was focally highly resistant just in the area of the

US anas-

wound

some

sonogram. pedis in situ

of these

taneously resolved in six patients on the next visit; follow-up was unavailable in one of these patients. In seven of nine other patients with diastolic elevation, transient increase in diastolic velocity was proved with angiography to be related to distal stenosis and AV shunting was not demonstrated (Fig 11). Three of these grafts had high focal PSV. Four grafts with abnormally low PSV and diastolic elevation had poor runoff from sites of

over

9. A longitudinal a femorodorsalis

third component of diastole the images.) Three months

became the US greater One pa-

artery that was noted at angiography but had not been examined with

it occurred

Figure strates

at angiog-

cases, the graft subsequently occluded. In another instance, scan was considered to show stenosis than the angiogram.

because tomosis. Five

months

flow

of 41 cm/sec. This remote distal ochad undergone graft occluded 4 thigh graft.

nous graft at the distal calf level, which has a PSV of 41 cm/sec but triphasic flow. (The

=

was

diminished

diastole and a PSV suggests significant disease. The patient angioplasties. The later. PTG = proximal

adjacent

=

raphy

very

(10 predomi-

to develop

the

not

flow with

sonogram shows

posi-

veins. Findings in 25 of the 36 angiograms (69.4%) in this group of patients were consistent with findings on US scans: normal flow, n = 5; low flow, n 3; stenosis, n = 12; AV shunting, n 2 (Fig 12); and graft occlusion, n = 3. Discordant findings (n = 11) occurred in two instances in which a stenosis

thigh

=

potential with

proximal

systolic

in early pattern clusive multiple

20

Note.-Nunibers are number ofgrafts. Sensitivity = live predictive value = 1/6 = 16.6%, negative predictive (1+ 227 = 228i253 = 90%.

stenoses

120

Present

Positive Negative

in the

8. A longitudinal in the proximal

which

fully

over

with

focal

spectral tions. Other

irregular patients

also time.

or disappearing

resolved Ten

increased analysis

unevent-

of 17 patients

diastolic also

had

flow fluid

findings

at US

included

rhythm

of the

heart

(Fig

17),

at

collecan

in seven

adenopathy

in six

patients, and a femoral anastomotic aneurysm in one patient. One patient had a retained venous valve that caused

increased

bulence

(Fig

PSV

18). One

and

patient

focal

tur-

had August

a 1991

Table 6 Findings

in Grafts

with

Diameter

Flow of 1-100

mL/min

Graft Occlusion at US

Finding

Present

Positive Negative

11 10

Total

21

Absent

Table

distal

anastomosis

high-grade was with days

with

stenosis

velocity.

At the

the dorsalis

pedis,

a

with a PSV of 163 cm/sec was successfully treated a sonogram obtained 6 that flow had returned to

present. This angioplasty; later showed

normal.

at US

superficial

thrombosis

seen

femoral

on the

vein

sonogram.

The

grafts

merous

tect

were

areas

local

focal either

examined

along

their

abnormalities.

in nupath

to de-

We detected

areas of high and low velocity, systolic or diastolic, or both,

and focal fluid collections. Except in five cases of open wounds overlying some areas of the graft, both proximal and distal anastomoses were well seen. Grafts that had an anastomosis with the dorsalis pedis artery could be just as easily identified as those at the tnfurcation beyond the popliteal artery. The typical normal peripheral yessel has a triphasic waveform at spectral analysis (5). The first systolic cornponent

90#{176} angle. Volume

rises

above

The 180

second Number

#{149}

the

baseline

diastolic 2

at a

corn-

value

specificity 150/160

=

150t231

=

64.9%,

=

93.8%, accuracy

=

=

mllmin

Absent

Total

77

Positive Negative

10 11

154

87 165

Total

21

231

252

= 10/21 predictive

=

47.6%, value

=

specificity 231/252

= =

1541231 = 66.6%, 91.7%, accuracy =

the next examination. However, in this group of 21 patients with a PSV of 40 cm/sec or less, seven of whom

ized

subsequently

as a high-resistance

arteries were

phasic

in diastole. has

not

triphasic.

triphasic, a dip

Biphasic

been

pattern.

were

without explained

regional

hypotension

outflow

resistance

but below

mono-

and

sion

in a graft

as being

related

These to

diminished distal

than

tnphasic

at spectral

arterial

analy-

sis, with some diastolic component above the baseline present but not elevated (Fig 14). Peripheral arteries typically

have

high-resistance

flow

with little diastole, comparable to that of the external carotid artery. Diastolic elevation, when it occurred, was not subtle and was categorized as a distinct abnormality associated with spectral

broadening

(Fig

had

occlusion

by

next visit, two died without and four others eventually

baseline

flow

of the

Most

Most

(1). A normal graft was considered to have an average PSV above 45 cm/sec but not above 115 cm/sec and was more likely biphasic or monophasic rather

DISCUSSION

predictive

Present

bed

concomitant

252

52.3%,

=

ponent descends below the baseline, followed by a final diastolic rise just above the baseline. This is character-

grafts diastolic

11/21

Graft Occlusion

femoral increased

=

with an Area Flow of 1-100

in 87 Patients

Note-Numbers are number of grafts. Sensitivity positive predictive value = 10/87 = 113%, negative (10 + 153 = 163t251 = 64.9%.

and

92 160

7

Findings

Finding

sec

81 150 231

Note-Numbers are number of grafts. Sensitivity positive predictive value = 11192 = 12.0%, negative (150 + 11 = 161)t252 = 63.9%. Figure 10. Contrast the normal spectral analysis of Figure 1 with this spectral analysis of a stenosis of the distal anastomosis in a similar graft where the PSV is 184 cm/sec, diastolic velocity is increased, and spectral broadening is prominent. G TO DP ANAS = graft to dorsalis pedis anastomosis.

Total

12).

Abnormal grafts had several different waveforms. Low blood velocity of 32 cm/sec or less was the single factor always associated with graft failure (Fig 8). Bandyk et al (2) initially suggested that low PSV of less than 40 cm/sec. and absence of diastolic flow were associated with graft occlusion, but in our study use of a PSV of only 40 cm/sec or less had a sensitivity of 33% for prediction of occlusion by

rates

(although

not

results are

Diastolic

by

indicate

the

that

the

follow-up had occlunext

visit).

low

flow

ominous.

flow

variations

cators of variance sence of diastolic sign of impending

were

mdi-

from the norm. Abflow was often a graft failure. Eleva-

tion of diastole throughout the graft in the first month after implantation suggested reactive hyperemia and was transient. Blackshear et al (4) showed that, by inflating a thigh cuff above systolic pressure for 3 minutes

and then releasing it, flow in the fernoral artery changed from a triphasic waveform to a transient monophasic one in which reverse diastolic flow disappeared

and

forward

diastolic

flow markedly increased, a response attributed to reactive hyperemia. Just as a transient stolic flow occurs

mesenteric stolic flow temporarily

increase in diain the superior

artery

after

in the after

extremity exercise.

eating,

diaincreases

Diastolic flow increases in AV shunting and also at sites of severe critical stenosis, either at focal areas along

the

graft

or as diffuse

or

increase

in diastolic flow the length of the graft in response to poor runoff (6-8). Diffuse increase in diastolic flow Radiology

383

#{149}

-

*

PAl

VEL

AVG

VEL PNGE

VTL

96

=

CM’

S

:-

.

1 M

iIl1

F1

KJG

a.

Figure 13. One week after graft placement, a longitudinal sonogram of a femorodorsalis pedis in situ saphenous graft at the calf shows normal PSV and increased diastolic velocity suggestive of AV shunting or poor runoff from distal occlusive disease, but these changes disappeared within the month, and

b.

the graft These

developed

findings

hyperemia.

;

normal

are

DCG

=

triphasic

consistent with distal calf graft.

flow. transient

w vtL,lcr

-‘,

-

-wcN 47

-=-

-;

CN”SIC

INVERTED

AFT

Figure 12. (a) Angiogram shows a taintly opacified femorodistal posterior tibial graft, which is outlined below the knee by surgical clips. The graft is shunting significant flow to the femoral venous system. (b) Sonogram of the same patient shows significant AV shunting with a normal PSV but increased diastolic velocity at the knee. Fluid is present anterior to the graft. In b and c, KIG = popliteal fossa. (c) On transverse section of the graft at the knee, the presence of a discrete fluid collection (arrowhead) is corroborated. Perimeter of the graft (A) is outlined. (d) At a site more distal than that in c, the spectral analysis of the graft in the distal calf has a more normal pattern of high resistance. DCG = distal calf graft.

throughout the graft may be transient because of reactive hyperemia in the first month after graft implantation,

but

after

1 month

such

a finding

sug-

gests vasodilatation due to arterial insufficiency from poor runoff. Focal high diastolic flow in associa-

tion

with

high

Normal

PSVs

PSVs

and

suggests focal

stenosis.

high

diastolic

AV

shunting.

velocity suggest AV shunting (two patients) or stenosis (two patients). In our study, in two cases of documented AV shunting, forward dias-

This

tolic flow was markedly but PSV was in large

increased, measure within

45

the

Estimated

range

of normal.

in milliliters

per

creased.

Prior

postocciusive

tive

and

hyperemia

increases

that than

in diastolic

with

ties greater creased

shown

than

Radiology

flow

that

findings

which showed (with a systolic graft associated cm/sec occlusive also found

in a prior

study

that monophasic waveform only) with a PSV less

flow of the than

was a predictor of a remote lesion (1,2). Bandyk et al (1) that a decrease of greater

graft shows monophasic PSV at the anastomosis

component-grafts failed.

One

that

patient

had

a normal

In one

veloci-

had suggested

distal

occlusive

lesion

in-

longer

curred graft, and This

patient

followed

than 2 years, consistently

with 25

cm/sec.

pattern

focal

readings but

over

up for

a low PSV throughout

oral graft. The stenoses ous

graft

that

bypasses

occur tend

in saphento develop

within 2 years, half of them within the first 8 months after graft placement (1). When stenoses were confirmed

on

angiograms,

the

with

time

as low

as 22

triphasic flow. was associated

range

of

PSV from

stolic

octhe

average

PSV but no diastolic flow throughout the graft. At angiography, he had a severe stenosis of the distal aortofem-

stenosis on US scans in this was 117-225 cm/sec. In two pahowever, focal graft stenoses

confirmed with angiography seen at US as areas of focal

a more

and

subsequently

cated

(1).

flow (ANAS).

with a better prognosis than those of grafts with low PSV and no diastolic

reacvelocity

400 mlJrnin

confirms

saphenous a normal

sonogram (10 pedis (DP) in situ

study tients,

mean velocity rather PSV (6). Several flow

grafts

14. A longitudinal of a femorodorsalis

Figure

MHz)

than 30 cm/sec in PSV compared with initial values postoperatively mdi-

substantial

flow

of these

TO OP

both

in-

with

estimated

diastolic

#{149}

was

postexercise

has

increase the the maximum

patients

384

minute

experience

flow

None

with high flow had occlusion. A low average PSV (32 cm/sec or lower) and absence of diastolic flow were always associated with graft failure in this study and were related to high outflow resistance; but an isolated, single reading of focal low PSV somewhere along the graft was not.

Al*IS

stenoses

flow in

grafts, patients

which (9),

Mild,

moderate,

changes

were

high diawith a normal PSV. Graft in situ saphenous vein occur in 21%-33% may be asymptomatic.

in the

or severe graft

lumen

of

stenotic can

August

be

1991

-

__;

-------

* -

-

-

ANAS

G

OP

A

Figure

15.

dorsalis (ANAS)

(DP) graft (G) anastomosis to indicate how well sonography can these small vessels. Arrowhead mdi-

define cates

Transverse

interface

pedis

scan

shows

a normal

pedis

with A

is circled.

bones graft.

=

of foot.

Dorsalis

.-

b.

a.

Figure 16. (a) Transverse sonogram shows a large fluid collection (arrowhead) anterior to the graft (A). CC = calf graft. (b) Four months after a was obtained, this fluid collection (arrowhead) has significantly decreased in size. A = graft, DCG = distal calf graft.

disease

(5,10).

that

Bandyk

the typical

sociated

et al reported

graft

with

stenosis

a decrease

sessment

was

in PSV

ascorn-

pared with that at the initial examinalion (1); Gngg et al noted that no graft with a severe stenosis had flow with a mean velocity greater than 50 cm/sec (10).

17. the irregular

Longitudinal sonogram shows rhythm of pulsus alternans on

the

analysis.

Figure

spectral

astolic MTG

=

Note

the

absence

flow. This graft subsequently middle thigh graft.

of di-

failed.

:r

cation

occurs

(12).

Of the

stolic

flow

-..

with

(1,10).

Just

a

as

standards have been suggested for reports of lower-extremity ischemia in the vascular surgery literature (11), criteria have been developed for the assessment

severe Volume

of mild,

peripheral 180

moderate,

arterial Number

#{149}

2

and

occlusive

in about

17 grafts pattern

10%

with at US,

of patients

a high

dia-

six eventu-

(14). duplex

of AV

saphenous ously

pulsed

close

in an in situ

graft

(15).

may

Kotval et al docuDoppler, an in-

shunting

vein

closed

with

that

Area

spontane-

and

diameter

flow calculations were not helpful in prediction of graft failure, but marked increases Others

suggested AV have reported

shunting. on both

frau-

matic and iatrogenic fernoral AV fistulas diagnosed with both duplex Doppler and color Doppler (16,17). While a focal high PSV and in creased diastolic velocity focally suggest graft stenosis, this is sometimes a transient pattern in the first weeks after graft placement.

middle-calf PSV of 127 cm/sec. but angiography only showed poor runoff. However, 4 months later these stenoses showed progression at US,

been described by Bandyk et al and attributed to revascularization hyperemia with associated vasodilatation and increased skin temperature (9) (Fig 13). The initial low resistant flow in in situ grafts suggests that flow is shunted until a new pathway of run-

plasty, cessful,

sonography

of all

spontaneously mented, with stance

graft

AV fistulas

Transient locity after

angiography confirmed stenoses were treated which and

them. with angio-

was only partially occlusion occurred.

all increased PSV, an indicator stenosis, leads to graft failure. patient

seen

in 73%

(13).

ally had occlusion

and The

:#{231}

Figure 18. Longitudinal sonogram shows proximal (PROK) in situ saphenous vein graft with a retained valve (arrowheads).

PSV

(35%). One patient was believed to have two graft stenoses at US because of a proximal PSV of 165 cm/sec and a

,

..s

study,

grafts, both normal and abnormal, decreased over time, and stenoses presented as areas of (a) focal high PSV, (b) normal or low PSV with increased diastolic flow, or (c) low PSV with absence of diastolic flow. A retained competent valve cusp was a source of marked focal turbulent flow and high PSV. This compli-

GRAFT*

A

In our

of the

Doppler

has

had

a proximal

sucNot

of One stenosis

with a PSV of 142 cm/sec that has not changed for over 1 year. Although a normal PSV and increased diastolic velocity suggest AV shunting, this pattern was more likely to be related to remote distal occlusive disease. This pattern occurred in in situ grafts only. AV shunting can also be detected

during

intraoperative

as-

off

has

increase in diastolic graft implantation

been

established.

One

yehas

patient

had

an initial high PSV of 274 cm/sec at US, along with high diastolic flow, but only minimal stenosis at angiography, and the PSV eventually returned to normal with no treatment, an mdication that this may have been fransient hyperemia. Pseudoaneurysm

cation

of graft

anastornotic holosystolic

and

below

sociated

raphy motic

is another

placement, aneurysms flow (ie,

the baseline with

defined aneurysm

turbulence

the

and

flow

compli-

these

typically both

have above

in systole) (18).

as-

Sonog-

proximal anastoof the femoral artery, Radiology

385

#{149}

but another aneurysm, distal to the graft, that was seen at angiography was not examined with US. The experience of surveillance with duplex Doppler of the vascular graft placed for peripheral artery disease is limited. Further experience and further refinements, such as the addition of color, promise an even more helpful noninvasive way to monitor the graft and have the potential to increase the sensitivity of predicting graft failure, allowing for intervention before occlusion develops. #{149} References 1.

Bandyk

mal human tents. 5.

6.

7.

8.

CR, Moldenhauer P. of vein graft steno-

et al. Hemodynamics sis. J Vasc Surg 1988; 8:688-695. 2.

Bandyk

DF, Cato

RF, Towne

JB.

A low

flow velocity predicts failure of femoropopliteal and femorotibial bypass grafts. Surgery 1985; 98:799-809. 3.

PolakJF,

nickJA,

4.

386

Donaldson MC, Dobkin CR, O’Leary CH. Early detection

saphenous

vein arterial

sis by color

assisted

bypass

10.

Manof

graft steno-

duplex sonography: AJR 1990; 154:857-861.

a

prospective study. Blackshear WM Jr, Phiffips DJ, Strandness DE Jr. Pulsed Doppler assessment of nor-

Radiology

#{149}

12.

Monata arterial

CL, Strandness duplex scanning.

651. Maher

F, Coen

DE. JCU

Peripheral 1987; 15:645-

11.

Nicholls Phillips

Cave-Bigley DJ, Ackroyd MA, Campbell H, Parry EW, Harris PL Complications associated with in situ vein grafts for femoropopliteal bypass. BrJ Surg 1984; 71:211221.

L,Johansen

KB, Bernstein

13.

UF, Fronek A. Post-ocdusion and postexercise flow velocity and ankle pressures in normals and marathon runners. Angiology 1976; 27:721-729.

9. DF, Seabrook

femoral artery velocity pat-

J Surg Res 1979; 27:73-83.

SC, Kohier TR, Martin RL, Neff R, DJ, Strandness DEJr. Diastolic flow as a predictor of arterial stenosis. Vasc Surg 1986; 3:498-501. Kohler TR, Nicholls SC, Zierler RE, Beach KW, Schubert PJ, Strandness DEJr. Assessment of pressure gradient by Doppler ultrasound: experimental and clinical observations. J Vasc Surg 1987; 6:460-469. Bandyk DF, Kaebnick HW, Stewart CS, Towne JB. Durability of the in situ saphenous vein arterial bypass: a comparison of primary and secondary patency. J Vasc Surg 1989; 5:256-268. Crigg MJ, Nicolaides AN, Wolfe JHN. Detection and grading of femorodistal vein graft stenoses: duplex velocity measurements compared with angiography. J Vasc Surg 1988; 8:661-666. Rutherford RB, Chairman, et al. Suggested standards for reports dealing with lower extremity ischemia. Ad Hoc Committee on Reporting Standards, Society for Vascular Surgery/North American Chapter, International Society for Cardiovascular Surgery. J Vasc Surg 1986; 4:80-94.

14.

Bandyk DF,Jorgensen traoperative assessment

RA, Towne JB. Inof in situ saphenous vein arterial grafts using pulsed Doppier spectral analysis. Arch Surg 1986; 121: 292-299. Bartlett ST. Killewich LA, Fisher REW. Duplex imaging of in situ saphenous vein bypass grafts and late failure reduction. AmJ

15.

tary 16.

17.

Surg

1988;

156:484-487.

Kotval PS, Shah PM, Barakat K. Doppler determination of in situ vein bypass tribufistula

and

its spontaneous

WD, Schwartz RA, Goldberg BB. latrogenic femoral arteriovenous fistula: diagnosis with color Doppler imaging. Radiology 1989; 170:749-752. Helvie MA, RubinJ. Evaluation of traumatic groin arteriovenous fistulas with du-

plex Doppler sonography. Med 1989; 8:21-24. 18.

closure

(letter). AJR 1989; 153:192-193. Igidbashian VN, Mitchell DC, Middleton

PolakJF,

Donaldson

MC,

J Ultrasound Whittemore

AD,

MannickJA, O’Leary DH. Pulsatile masses surrounding vascular prostheses: real-time US color flow imaging. Radiology 1989; 170:363-366.

August1991

Lower-extremity vascular grafts placed for peripheral vascular disease: prospective evaluation with duplex Doppler sonography.

Eighty-five men with 92 vascular grafts placed for peripheral vascular disease of the lower extremity underwent a total of 264 examinations with duple...
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