Quantitative Ultrasonographic Studies ofLower Extremity Flow Velocities

in Health and DiseaseA. FRONEK, M.D., M. COEL, M.D.,

AND E. F. BERNSTEIN, M.D.

SUMMARY Quantitative Doppler ultrasonographic flow velocitydeterminations are reported from 39 normal control subjects and 80patients with angiographically documented peripheral arterial dis-ease, in whom femoral, posterior tibial and dorsalis pedis arterieswere studied. The mean control values of the most useful parameterswere: femoral artery: peak forward velocity (PFV) cm/sec:40.7 ± 10.9, deceleration (Dec.) cm/sec 2: 250.9 ± 60.0, peak/meanvelocity (P/MV): 4.8 ± 1.6; posterior tibial artery: PFV:

CLINICAL EVALUATION of peripheral arterial occlu-sive disease depends upon the history, physical examination,certain noninvasive techniques and angiography especiallyin cases where vascular reconstruction is considered. Anumber of noninvasive methods have been developed toassist the functional assessment of the circulatory con-

ditions of the peripheral arterial system. One recently in-troduced technique is the ultrasonic determination of flowvelocity using the Doppler principle.' 2 The diagnostic valueof this technique has been demonstrated by a number ofauthors.3 In most studies, only qualitative aspects of theDoppler velocity ultrasonogram have been observed,primarily because earlier Doppler devices were in- --able ofdirectional sensitivity. Based on the contributions ofMcLeod," a directionally sensitive Doppler velocity meterwas developed, permitting quantitative noninvasivemeasurements of peripheral arterial velocity. A preliminarystudy describing calibration and correlation studies with an

electromagnetic flow meter was previously reported fromthis laboratory.9

Directional sensitive ultrasonic Doppler measurementshave been used as a part of a noninvasive diagnostic testpanel in over 1800 patients in the UCSD Vascular Diag-nostic Laboratories since 1971.10 Observations in thirty-ninehealthy volunteers and eighty patients with angiographical-ly documented arterial disease have been analyzed to pro-

vide information regarding the reproducibility of the meas-

urements and their sensitivity in demonstrating and quanti-tating arterial disease of the lower extremity.

Method

In these studies, the Parks 806 Doppler Directional Ve-locity Meter was used following in vitro calibration with an

excised canine vessel as previously described.9 The can-

From the Departments of AMES-Bioengineering, Radiology and Surgery,School of Medicine, University of California-San Diego, La Jolla, Cali-fornia.

Supported by grant HL 18977-01 from the NIH.Address for reprints: Dr. A. Fronek, AMES-Bioengineering, School of

Medicine, Basic Science Building, Room 5028, UCSD, La Jolla, California92093.

Received December 19, 1975; revision accepted for publication January 26,1976.

16.0 ± 10.0, Dec.: 129.8 + 75.7, P/MV: 4.8 ± 2.5; dorsalis pedisartery: PFV: 168 ± 5.7, Dec.: 137.9 ± 54.5, P/MV: 6.0 ± 4.1. Thevalues of these measurements in the patients with arterial occlusivedisease were all significantly lower, and also permitted distinguishingthose with multilevel disease from those with a single site of occlu-sion. Quantitative evaluation of the Doppler ultrasonogram permitsobtaining detailed functional information on the degree of arterialflow impairment in patients with peripheral arterial occlusive disease.

nulated vessel is perfused with blood and the time collec-tions are taken. The output voltage is plotted against flowvelocity (obtained by dividing the flows by the measured in-ternal cross-sectional area of the excised vessel). Signalswere studied from the femoral, posterior tibial and dorsalispedis arteries, and recorded on a Hewlett-Packard model7788A multichannel recorder.To obtain the most reproducible results, the recorded

signal is scanned for maximum amplitude by moving theprobe horizontally in the area of the expected signal. Afteridentifying the maximum signal, the angle of the probe posi-tion is varied again for maximum signal recovery, which isusually at approximately 450 to the inflow. The probe is thenfixed in position with a magnetic clamp.*The following control studies were performed to evaluate

the reproducibility of the data. Ten healthy volunteers(20-27 years) were studied by measuring the flow velocitiesin the femoral, posterior tibial and dorsalis pedis arteries.After the first measurement, the probe was removed and thestudy repeated twice, at 15-minute intervals. Left and rightleg values were compared. Peak forward and reversevelocity, mean velocity (obtained electronically using the 0.1c/s upper frequency cut-off filter of the HP BioelectricAmplifier), pulse rise and decay time (from the onset to thepeak and from the peak to baseline, respectively) weremeasured directly from the recorded velocity tracings (fig.1). The following values were then calculated: acceleration(first derivative of velocity, therefore: peak velocity/pulserise time), deceleration (peak velocity/pulse decay time), ac-celeration/deceleration ratio (ADR), and the peak ve-locity/mean velocity ratio (PMR).

Eighty patients with angiographically documentedarterial disease were divided into the following groups:Group I - Isolated aorto-femoral obstruction;Group II - Obstruction limited to femoro-popliteal

segment or distal to the popliteal trifur-cation;

Group III - Significant aorto-femoral disease com-bined with femoral, popliteal or,distal tibio-peroneal obstruction (multilevel disease).

*Flex-O-Post Indicator Holder with Magnetic Base, Starrett Company,Athol, Massachusetts.

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VOL. 53, No. 6, JUNE 1976

FORWARD VELOCITY

\MEAN VELOCITYPULSE RISE TIME

PULSE DECAY TIME SPEAK REVERSE VELOCITY

ACCELERATION =

PULSE RISE TIME

DECELERATION = PEAK VELOCITYPULSE DECAY TIME

FIGURE 1. Diagram of a normal flow velocity pulse.

Statistical Analysis

The reproducibility of repeated measurements, and thedifference between the left and right leg values were analyzedby means of the paired t-test.1' The three patient groupswere compared with the control group and with each other.

Results

Reproducibility. Three consecutive measurements at 15-minute intervals with repositioning of the probe each timeyielded measurements within one standard deviation of themean, when all recorded and calculated data obtained from

the left and right leg were compared. The differences werebelow the level of statistical significance (table 1).

Table 2 summarizes the velocity data obtained from 39healthy control subjects (19-32 years), with the correspond-ing mean values and standard deviations. Figure 2 repro-duces a normal ultrasonogram shown with a simultaneouslyrecorded ECG.

Table 3 summarizes the results obtained in all threegroups of patients with arterial occlusive disease. By com-

paring these results with those obtained from the controlgroup, it can be recognized that some parameters have a

higher diagnostic value than others. Deceleration, peakvelocity/mean velocity and peak forward velocity were themost sensitive parameters differentiating the control groupfrom the groups of patients with arterial occlusive disease.Similarly, these parameters, and the peak reverse velocity,were most helpful in differentiating multilevel (Group III)from single level disease (Groups I and II).

Figure 3 depicts velocity ultrasonograms from a patientwith aorto-iliac stenosis, while figure 4 documents an almostnormal femoral artery flow velocity tracing with depressedposterior tibial and dorsalis pedis artery velocities in a pa-tient with superficial femoral artery stenosis.

Discussion

It is difficult to compare results of flow velocity measure-

ments (velocity = flow/cross-sectional area) with venous

occlusion plethysmographic blood flow determinations (ex-pressed in volume/time/limb volume). However, it is per-tinent to point out that this report demonstrates essential

TABLE 1. Reproducibility TestPeak forward Peak reverse Peak vel. Accel.velocity velocity Mean velocity Acceleration Deceleration Peak vel. Accel.

(cm/sec) (cm/see) (cm/sec) (cm/sec2) (cm/sec2) Mean vel. Decel.

Femoral arteryTest 1 46.9 - 26.4* 4.88 4.9 11.05 - 6.4 406.4 +223.9 282.5 i 156.3 4.76 - 1.6 1.4 = 0.4Test 2 47.6 - 26.9 5.10 4.5 11.25 - 7.5 430.5 287.4 292.0 - 146.8 4.70 - 1.5 1.5 - 0.5Test 3 46.8 - 25.5 6.43 4.9 11.29 - 8.6 388.9 209.4 288.8 - 148.5 4.81 - 1.5 1.3 - 0.4N = 20

Posterior tibial arteryTest 1 15.71 - 10.4 0.91 1.27 3.93 - 3.39 140.5 78.9 126.5 = 73.0 4.69 = 2.51 1.1 - 0.6Test 2 16.63 - 10.5 1.13 1.44 4.00 - 3.50 149.6 73.5 133.8 = 77.5 4.87 = 2.16 1.1 - 0.5Test 3 15.57 - 9.7 1.50 1.76 4.02 = 3.76 149.9 i76.7 129.1 - 82.5 4.97 - 2.89 1.2 - 0.7N = 20

Dorsal pedis arteryTest 1 17.5 - 6.1 0.93 1.7 3.4 1.5 166.6 55.3 135.5 - 56.8 5.99 - 3.3 1.2 i0.7Test 2 16.6 - 5.6 1.33 2.1 3.5 1.8 159.5 56.3 138.4 - 60.3 5.54 - 3.2 1.2 0.7Test 3 16.4 i 5.1 1.18 1.6 3.1 1.4 154.6 51.4 136.4 - 49.62 6.50 - 5.5 1.1 0.9N = 17*Mean 4 SD.

TABLE 2. Normal ValuesPeak forward Peak reverse

velocity velocity Mean velocity Acceleration Deceleration Peak ve]. Accel.(cm/sec) (cm/sec) (cm/sec) (cm/Sec2) (cm/Sec2) mean vel. Decel.

Femoral artery 40.7 - 10.9* 6.5 = 3.6 9.8 - 5.3 353.0 = 113.1 250.9 - 60.0 4.8 i 1.6 1.4 - 0.2N = 78 extremitiesPosterior tibial artery 16.0 - 10.0 2.0 i 2.3 4.0 i 3.5 145.0 = 73.7 129.8 - 75.7 4.8 - 2.5 1.2 - 0.1N = 78Dorsal pedis artery 16.8 - 5.7 1.3 ± 2.2 3.4 = 1.6 160.5 - 55.3 137.9 - 54.5 6.0 4.1 1.3 - 0.5N = 73*Mean + SD.

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FLOW VELOCITIES IN HEALTH AND DISEASE/Fronek, Coel, Bernstein

Pa/lent if 764FEMORAL ARTERY POSTERIOR TIBIAL ARTERY DORSALIS PEDIS ARTERY

EKG-iwo - o-_ -r W ; W

40

VELOCITY \ f A(cm/sec) , ,_ __

FIGURE 2. Normal velocity ultrasonogram. Paper speed 25 mm/sec; lower paper speed (I mm/sec) at the end of eachtracing while recording mean flow velocity.

Pofient 1766FEMORAL ARTERY POSTERIOR TIBIAL ARTERY DORSALIS PEDIS ARTERY

_ ;,

401

VELOCITY(cm /sec)

FiuURE 3. Aorto-iliac stenosis. Paper speeds as above.

TABLE 3. Summarized Table: Normal Compared with Pathological GroupsPeak Peak

forward reverse MIeanvelocity velocity velocity Acceleration Deceleration Peak vel. Aceel.(cm/see) (cm/see) (cm/see) (cm/see2) (Cm/see2) Mean vel. Decel.

Femoral arteryNormal 40.7 -1= 10.9 6.5 i 3.6 9.8 5.3 353.0 113.1 250.9 60.0 4.8 + 1.6 1.4 0.2N = 78

Group I 25.8 9.4 3.5 3.5 8.9 2.9 260.7 176.6 122.9 73.6 3.1 1.1 2.0 1.1N - 14 +++

Group II 30.3 - 15.4 4.2 4.4 8.9 4.2 352.5 193.8 181.0 117.0 3.6 0.8 2.2 I 1.1N = 27 *** +++ +++ +++ *** +++ *** +++

Group III 20.9 11.2 0.8 1.9 7.9 * 4.2 208.5 166.2 91.0 70.7 2.7 +0.8 2.7 * 1.6N = 70 *

Posterior tibial arteryNormal 16.0 10.0 2.0 2.3 4.0 * 3.5 145.0 - 73.7 129.8 4 75.7 4.8 ^2.5 1.2 0.1N = 78

Group I 13.4 11.5 2.2 2.9 4.4 3.3 165.7 191.8 79.2 62.4 3.0 0.76 1.9 i 0.9N = 14 +++ + +++

Group II 13.3 6.6 1.2 - 1.5 7.4 7.0 121.7 59.5 77.2 82.9 2.8 1.1 1.8 0.7N = 25 + ** ** ++ *** +++ ***

Group III 11.7 = 8.2 0.4 - 1.1 5.2 4.2 89.6 64.7 43.0 = 40.2 2.1 f 0.8 2.5 1.5N 66 * ** *** **

Dorsal pedis arteryNormal 16.8 5.7 1.3 - 2.2 3.4 1.6 160.5 55.3 137.9 - 54.5 6.0 - 4.1 1.3 + 0.5N = 73

Group 1 14.7 L 6.4 2.0 2.4 4.7 2.4 168.2 121.4 79.9 fi50.8 3.4 = 1.5 2.0 0.8N - 13 +++ +++ +++ *** +++ +++

Group II 11.4 9.2 0.9 1.9 4.3 3.2 116.9 93.4 71.8 - 55.0 2.6 0.9 2.0 1.1N = 27 **** *** +t+ *** ±

Group III 6.9 6.5 0.2 - 0.5 3.6 3.4 68.9 65.9 28.9 20.8 2.0 ^ 0.7 2.6 1.4N = 60 *** *** *** *** *** **

* or + = significant at P < 0.01.** or + + = significant at P < 0.005.***or + ++ = significant at P < 0.001.

*Control group vs I, 11 or 111.+ = Group III vs I or II.

EKG

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VOL. 53, No. 6, JUNE 1976

FEMORAL ARTERY POSTERIOR TIBIAL ARTERY DORSALIS PEDIS ARTERY

-t-----.------.-.-.W-------.L.. A A

40i

4°

VELOCITY(em/see)

J

FiG.URE 4. Superficial femoral artery occlufsion. Paper speeds as above.

agreement with a number of venous occlusion plethys-mographic studies12 14 that show resting mean flow velocityis not a reliable index of peripheral arterial occlusive disease.A closer analysis of the results shows that while very ad-vanced arterial disease significantly restricts resting mean

arterial flow velocity, it does not provide reliable separationbetween moderately advanced disease and the control group.

The explanation is probably related to the fact that vaso-

motor adjustment tends to compensate mean flow velocityto a considerable extent, as has been shown in previousstudies with various flow metering techniques.15-18

In contrast, certain components of the velocity pulse are

very sensitive indicators of arterial obstruction. It is pre-

mature to attempt a ranking of sensitivity or reliability ofthese derived values prior to experimental experience.However, based on the present data, peak flow velocity anddeceleration are very sensitive indicators of hemodynam-ically significant arterial obstruction. In addition, both thepeak/mean velocity and acceleration/deceleration ratios are

highly sensitive indices. The decrease of the first ratio withincreasing flow obstruction can be explained by an attenua-tion of the higher harmonic components while the "D.C."component of the flow velocity pulse was not significantly in-fluenced. The change in the flow velocity pattern seems to beresponsible for the sensitivity of the acceleration/decelera-tion ratio: deceleration decreases earlier than accelerationwith increasing flow obstruction.

Acknowledgment

We express our thanks to Jon Belsha, Nancy Zamfirescu and Robert Garzafor their assistance in this study.

References

1. Satomura S, Kaneko L: Ultrasonic Blood Rheograph. (abstr) London,3rd Internat Conf Med Electron, 254, 1960

2. Franklin DL, Schlegel W, Rushmer RF: Blood flow measured byDoppler frequency shift or back-scattered ultrasound. Science 134: 564,1961

3. Rushmer RF, Baker DW, Stegall HF: Transcutaneous Doppler flowdetection as a nondestructive technique. J Appl Physiol 21: 554, 1966

4. Strandness DE Jr, McCutcheon EP, Rusmer RF: Application of a trans-cutaneous Doppler flowmeter in evaluation of occlusive arterial disease.Surg Gynec Obstet 122: 1939, 1966

5. Strandness DE Jr, Schultz RD, Sumner DS, Rusmer RF: Ultrasonic flowdetection: a useful technique in the evaluation of peripheral vascular dis-ease. Am J Surg 113: 311, 1967

6. McLeod ED Jr: Directional Doppler demodulation. (abstr) Proceedingsof the Twentieth Annual Conference on Engineering in Medicine andBiology 27: 1, 1967

7. McLeod FD: Calibration of CW and pulse Doppler flowmeter.Proceedings of the Twenty-Third Annual Conference in Engineering inMedicine and Biology 21: 2, 1970

8. Strandness DE Jr, Kennedy JW, Judge TP, McLeod FD: Trans-cutaneous directional flow detection: a preliminary report. Am Heart J78: 65, 1969

9. Bernstein EF, Murphy AE Jr, Shea MA: Experimental and clinical ex-

perience with transcutaneous Doppler ultrasonic flowmeters. Arch Surg101: 21, 1970

10. Fronek A, Johansen KN, Dilley RB, Bernstein EF: Non-invasive phys-iologic tests in the diagnosis and characterization of peripheral arterialocclusive disease. Am J Surgery 126: 206, 1973

11. Snedecor GW: Statistical Methods, ed 5. Ames, Iowa State UniversityPress, 1956, ch 10

12. Hillestad LK: The peripheral blood flow in intermittent claudication.Acta Med Scand 174: 671, 1963

13. Bollinger A: Durchblutungsmessungen in der klinischen Angiologie unterbesonderer Berucksichtigung der Venenverschluss-plethysmographie.Bern, Verlag Hans Huber, 1969

14. Ehringer H: Die reaktive Hyperamie nach arterieller Sperre. In Mess-methoden bei arteriellen Durchblutungsstorungen, edited by Bollinger A,Brunner U. Bern, H. Huber, 1971, p 20

15. Agrifoglio G, Thorburn GD, Edwards EA: Measurement of blood flow inhuman lower extremity by indicator-dilution method. Surg Gynec Obstet113: 641, 1961

16. Ganz V, Hlavova A, Fronek, A, Linhart J, Prerovsky 1: Measurement ofblood flow in the femoral artery in man at rest and during exercise bylocal thermodilution. Circulation 30: 86, 1964

17. Lassen NA, Lindbjerg IF, Dahn I: Validity of the Xenon'31 method forthe measurement of muscle blood flow evaluated by simultaneous venous

occlusion plethysmography: observations in the calf of normal man andin patients with occlusive vascular disease. Circ Res 16: 287, 1964

18. Folse R: Application of sudden injection dye dilution principle to thestudy of the femoral circulation. Surg Gynec Obstet 120: 1194, 1965

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A Fronek, M Coel and E F Bersteindisease.

Quantitative ultrasonographic studies of lower extremity flow velocities in health and

Print ISSN: 0009-7322. Online ISSN: 1524-4539 Copyright © 1976 American Heart Association, Inc. All rights reserved.

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