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Rofsky NM, Adelman MA. Because of the multiple etiologies of upper extremity arterial disease, consider: to assess the type and duration of symptoms, evidence of skin changes and differences in color. MR angiography in the evaluation of atherosclerotic peripheral vascular disease. The relationship between calf blood flow and ankle blood pressure in patients with intermittent claudication. Although stenosis of the proximal upper extremity arteries is most often caused by atherosclerosis, other pathologies include vasculitis, trauma, or thoracic outlet compression. COMPARISON OF BLOOD PRESSURES IN THE ARMS AND LEGS. A meta-analysis of 20 studies in which MDCT was used to evaluate 19,092 lower extremity arterial segments in 957 symptomatic patients compared test performance with DSA [49]. The test is performed with a simple handheld Doppler and a blood pressure cuff, taking. Introduction to Measuring the Ankle Brachial Index This finding may indicate the presence of medial calcification in the patient with diabetes. 13.20 ). (A) Note the low blood flow velocities with a peak systolic velocity of 12cm/s and high-resistance pattern. A venous signal can be confused with an arterial signal (especially if pulsatile venous flow is present, as can occur with heart failure) [11,12]. Well-developed collateral vessels may diminish the observed pressure gradient and obscure a hemodynamically significant lesion. Diabetes Care 2008; 31 Suppl 1:S12. ). ABI >1.30 suggests the presence of calcified vessels. The steps for recording the right brachial systolic pressure include, 1) apply the blood pressure cuff to the right arm with the patient in the supine position, 2) hold the Doppler pen at a 45 angle to the brachial artery, 3) pump up the blood pressure cuff to 20 mmHg above when you hear the last arterial beat, 4) slowly release the pressure ABPI was measured . Mild disease is characterized by loss of the dicrotic notch and an outward bowing of the downstroke of the waveform (picture 3). Decreased peripheral vascular resistance is responsible for the loss of the reversed flow component and this finding may be normal in older patients or reflect compensatory vasodilation in response to an obstructive vascular lesion. The clinical presentations of various vascular disorders are discussed in separate topic reviews. When performing serial examinations over time, changes in index values >0.15 from one study to the next are considered significant and suggest progression of disease. The following transition points define the major arteries supplying the arm: (1) from subclavian to axillary artery at the lateral aspect of the first rib; (2) axillary to brachial artery at the lower aspect of the teres major muscle; (3) trifurcation of the brachial artery to ulnar, radial, and interosseous arteries just below the elbow. Surgery 1995; 118:496. The triphasic, high-resistance pattern is now easily identified. Note that although the pattern is one of moderate resistance, blood flow is present through diastole. 13.7 ) arteries. (See 'Continuous wave Doppler'below and 'Duplex imaging'below.). It is therefore most convenient to obtain these studies early in the morning. Interventional Radiology Sonographer Vascular Ultrasound case: Upper Extremity Arterial PVR, Segmental Pressures and wrist brachial index interpretation. AbuRahma AF, Khan S, Robinson PA. Vasc Med 2010; 15:251. 2012; 126:2890-2909. doi: 10.1161/CIR.0b013e318276fbcb Link Google Scholar; 15. The smaller superficial branch continues into the volar (palmar side) aspect of the hand (, Examining branches of the deep palmar arch. However, the intensity and quality of the continuous wave Doppler signal can give an indication of the severity of vascular disease proximal to the probe. Adriaensen ME, Kock MC, Stijnen T, et al. A normal toe-brachial index is 0.7 to 0.8. Cuffs are placed and inflated, one at a time, to a constant standard pressure. Generally, three cuffs are used with above and below elbow cuffs and a wrist cuff. The Toe Brachial Pressure Index is a non-invasive method of determining blood flow through the arteries in the feet and toes, which seldom calcify. Screening for asymptomatic PAD is discussed elsewhere. Wound healing in forefoot amputations: the predictive value of toe pressure. the left brachial pressure is 142 mmHg. If any of these problems are suspected, additional testing may be required. Mohler ER 3rd. Aesthetic Dermatology. (See "Treatment of lower extremity critical limb ischemia"and "Percutaneous interventional procedures in the patient with claudication". J Cardiovasc Surg (Torino) 1982; 23:125. Normally, the pressure is higher in the ankle than in the arm. 13.1 ). Accurate measurements of Doppler shift and, therefore, velocity measurements require proper positioning of the ultrasound probe relative to the direction of flow. The procedure resembles the more familiar ABI. Intermittent claudication: an objective office-based assessment. Hirsch AT, Haskal ZJ, Hertzer NR, et al. (A) Plaque is seen in the axillary (, Arterial occlusion. (A) The distal brachial artery can be followed to just below the elbow. Visceral arteries Duplex examination of visceral arteries, especially the renal arteries, requires the use of low frequency transducers to penetrate to the depth of these vessels. Mortality and cardiovascular risk across the ankle-arm index spectrum: results from the Cardiovascular Health Study. Other studies frequently used to image the vasculature include computed tomography (CT) and magnetic resonance (MR) imaging. At the wrist, the radial artery anatomy gets a bit tricky. Methods: A systematic review was conducted on publications after 1990 in Google Scholar, Scopus, and PubMed databases. Inflate the blood pressure cuff to about 20 mmHg above the patient's regular systolic pressure or until the whooshing sound from the Doppler is gone. In the upper extremities, the extent of the examination is determined by the clinical indication. Low calf pain Pressure gradient from the calf and ankle is indicative of infrapopliteal disease. (See 'Pulse volume recordings'above.). the right posterior tibial pressure is 128 mmHg. A low ABI is associated with a higher risk of coronary heart disease, stroke, transient ischemic attack, progressive renal insufficiency, and all-cause mortality [20-25]. (A) As it reaches the wrist, the radial artery splits into two. J Am Coll Cardiol 2010; 55:342. Hiatt WR. J Vasc Surg 2007; 45 Suppl S:S5. The standard examination extends from the neck to the wrist. Bowers BL, Valentine RJ, Myers SI, et al. ), Provide surveillance after vascular intervention. Ann Surg 1984; 200:159. The ankle brachial index (ABI) is the ratio between the blood pressure in the ankles and the blood pressure in the arms. A . PAD can cause leg pain when walking. Blood pressure cuffs are placed at the mid-portion of the upper arm and the forearm and PVR waveform recordings are taken at both levels. It goes as follows: Right ABI = highest right ankle systolic pressure / highest brachial systolic pressure. Normal upper extremity Doppler waveforms are triphasic but the waveforms can change in response to the ambient temperature and to maneuvers such as making a fist, especially when acquired near the hand ( Fig. PPG waveforms should have the same morphology as lower extremity wavforms, with sharp upstroke and dicrotic notch. 1) Bilateral brachial arm pressures should not differ by more than 20 mmHg 2) Finger/Brachial Index a. Thrombus or vasculitis can be visualized directly with gray-scale imaging, but color and power Doppler imaging are used to determine vessel patency and to assess the degree of vessel recanalization following thrombolysis. (D) The ulnar Doppler waveforms tend to be similar to the ones seen in the radial artery. J Am Coll Cardiol 2001; 37:1381. 13.13 ). The formula used in the ABI calculator is very simple. Interpreting the Ankle-Brachial Index The ABI can be calculated by dividing the ankle pressures by the higher of the two brachial pressures and recording the value to two decimal places. While listening to either the dorsalis pedis or posterior tibial artery signal with a continuous wave Doppler (picture 1) , insufflate the cuff to a pressure above which the audible Doppler signal disappears. The wrist pressure do sided by the highest brachial pressure. Both B-mode and Doppler mode take advantage of pulsed sound waves. The lower the number, the more . Finger Pressure Digit-Brachial Index (DBI) is the upper extremity equivalent of the lower extremity Ankle-Brachial Index. Angel. (See 'Pulse volume recordings'below.). Noninvasive physiologic vascular studies allow evaluation of the physiologic parameters of blood flow through segmental arterial pressures, Doppler waveforms, and pulse volume recordings to determine the site and severity of lower extremity peripheral arterial disease. If the ABI is greater than 0.9 but there is suspicion of PAD, postexercise ABI measurement or other noninvasive options . In general, only tests that confirm the presence of arterial disease or provide information that will alter the course of treatment should be performed. (A and B) Long- and short-axis color and power Doppler views show occlusion of an axillary artery (, Doppler waveforms proximal to radial artery occlusion. The TBI is obtained by placing a pneumatic cuff on one of the toes. Critical issues in peripheral arterial disease detection and management: a call to action. Only tests that confirm the presence of arterial disease,further define the level and extent of vascular pathologyor provide information that will alter the course of treatment should be performed.Vascular testing may be indicated for patients with suspected arterial disease based upon symptoms (eg, intermittent claudication), physical examination findings (eg, signs of tissue ischemia), or in patients who are asymptomatic with risk factors for atherosclerosis (eg, smoking, diabetes mellitus) or other arterial pathology (eg, trauma, peripheral embolism) [1]. Ann Vasc Surg 1994; 8:99. (See 'Exercise testing'above. Compared to the arm, lower blood pressure in the leg suggests blocked arteries due to peripheral artery disease (PAD). 0.97 c. 1.08 d. 1.17 b. Obtaining the blood pressure in these two locations allows your doctor to perform an ankle-brachial index calculation that shows whether or not you have reduced blood flow in your legs. Epub 2012 Nov 16. The large arteries of the upper arm and forearm are relatively easy to identify and evaluate with ultrasound. 13.8 to 13.12 ). Selective use of segmental Doppler pressures and color duplex imaging in the localization of arterial occlusive disease of the lower extremity. To differentiate from pseudoclaudication (atypical symptoms). Effect of MDCT angiographic findings on the management of intermittent claudication. In some cases both might apply. Measurement and interpretation of the ankle-brachial index: a scientific statement from the American Heart Association. Graded routines may increase the speed of the treadmill, but more typically the percent incline of the treadmill is increased during the study. A more severe stenosis will further increase systolic and diastolic velocities. The spectral band is narrow and a characteristic lucent spectral window can be seen between the upstroke and downstroke. To investigate the repercussions of traumatic brachial plexus injury (TBPI) on diaphragmatic mobility and exercise capacity, compartmental volume changes, as well as volume contribution of each hemithorax and ventilation asymmetry during different respiratory maneuvers, and compare with healthy individuals. Physiologic tests include segmental limb pressures and the calculation of pressure index values (eg, ankle-brachial index, wrist-brachial index), exercise testing, segmental volume plethysmography, transcutaneous oxygen measurements and photoplethysmography. Schernthaner R, Fleischmann D, Lomoschitz F, et al. BMJ 1996; 313:1440. The patients must rest for 15 to 30 minutes prior to measuring the ankle pressure. The ankle-brachial index is associated with the magnitude of impaired walking endurance among men and women with peripheral arterial disease. Apelqvist J, Castenfors J, Larsson J, et al. The dicrotic notch may be absent in normal arteries in the presence of low resistance, such as after exercise. A three-cuff technique uses above knee, below knee, and ankle cuffs. The principles of testing are the same for the upper extremity, except that a tabletop arm ergometer (hand crank) is used instead of a treadmill. TBPI Equipment ), Ultrasound is routinely used for vascular imaging. If the high-thigh pressure is normal but the low-thigh pressure is decreased, the lesion is in the superficial femoral artery. Intraoperative transducers work quite well for imaging the digital arteries because they have a small footprint and operate at frequencies between 10 and 15MHz. However, the examination is expensive and also involves radiation exposure and the intravenous contrast agents. The axillary artery dives deeply, and at this point, the arm is raised and the probe is repositioned in the axilla to examine the axillary artery. Then follow the axillary artery distally. With a four cuff technique, the high-thigh pressure should be higher than the brachial pressure, though in the normal individual, these pressures would be nearly equal if measured by invasive means. PASCARELLI EF, BERTRAND CA. Does exposure to cold or stressful situations bring on or intensify symptoms? ), For symptomatic patients with an ABI 0.9 who are possible candidates for intervention, we perform additional noninvasive vascular studies to further define the level and extent of disease. MRA is usually only performed if revascularization is being considered. Falsely elevated due to . Surg Gynecol Obstet 1978; 146:337. interpretation of US images is often variable or inconclusive. Segmental pressures can be obtained for the upper or lower extremity. What is the formula used to calculate the wrist brachial index? Signs [ edit ] Pallor Diminished pulses (distal to the fistula) Necrosis [1] Decreased wrist- brachial index (ratio of blood pressure measured in the wrist and the blood pressure [en.wikipedia.org] It is commoner on the left side with L:R ratio of ~3:1. ipsilateral upper limb weak or absent pulse decreased systolic blood pressure in the . Normal continuous-wave Doppler waveforms have a high-impedance triphasic shape, characteristic of extremity arteries (with the limb at rest). The Toe Brachial Index (TBI) is defined as the ratio between the systolic blood pressure in the right or left toe and the higher of the systolic pressure in the right or left arms. The principal effect is blood flow reduction because of stenosis or occlusion that can result in arm ischemia. Brachial artery PSVs range from 50 to 100cm/s. The infrared light is transmitted into the superficial layers of the skin and the reflected portion is received by a photosensor within the photo-electrode. Ultrasonography is used to evaluate the location and extent of vascular disease, arterial hemodynamics, and lesion morphology [10]. SCOPE: Applies to all ultrasound upper extremity arterial evaluations with pressures performed in Imaging Services / Radiology . TBPI who have not undergone nerve . ABI >1.30 suggests the presence of calcified vessels, For patients with a normal ankle-brachial index (ABI) who have typical symptoms of claudication, we suggest exercise testing. The ankle-brachial index (ABI) is an easy, non-invasive test for peripheral artery disease (PAD). https://doi.org/10.1016/j.jhsa.2013.01.024 Get rights and content Here's what the numbers mean: 0.9 or less. Specialized imaging of the hand can be performed to detect disease of the digital arteries. 13.3 and 13.4 ), axillary ( Fig. Physiologic tests include segmental limb pressures and the calculation of pressure index values (eg, ankle-brachial index, toe-brachial index, wrist-brachial index), exercise . Face Wrinkles. PURPOSE: To determine the presence, severity, and general location of peripheral arterial occlusive disease in the upper extremities. Index values are calculated at each level. When followed, the superficial palmar arch is commonly seen to connect with the smaller branch of the radial artery shown in, Digital artery examination. Single-level disease is inferred with a recovery time that is <6 minutes, while a 6 minute recovery time is associated with multilevel disease, particularly a combination of supra-inguinal and infrainguinal occlusive disease [13]. Murabito JM, Evans JC, Larson MG, et al. It is used primarily for blood pressure measurement (picture 1). (See "Creating an arteriovenous fistula for hemodialysis"and "Treatment of lower extremity critical limb ischemia". Deflate the cuff and take note when the whooshing sound returns. (A) This is followed by another small branch called the radialis indicis, which travels up the radial side of the index finger. Kohler TR, Nance DR, Cramer MM, et al. These two arteries sometimes share a common trunk. Multidetector row CT angiography of the abdominal aorta and lower extremities in patients with peripheral arterial occlusive disease: diagnostic accuracy and interobserver agreement. Environmental and muscular effects. Resnick HE, Lindsay RS, McDermott MM, et al. the PPG tracing becomes flat with ulnar compression. Muscle Anatomy. Circulation 2004; 109:2626. Thirteen of the twenty patients had higher functioning in all domains of . Surgery 1969; 65:763. Hiatt WR, Hirsch AT, Regensteiner JG, Brass EP. These objectives are met by obtaining one or more tests including segmental limb pressures, calculation of index values (ankle-brachial index, wrist-brachial index, toe-brachial index), pulse volume recordings, exercise testing, digit plethysmography and transcutaneous oxygen measurements. Finally, if nonimaging Doppler and PPG waveforms suggest arterial obstructive disease, duplex imaging can be done to identify the cause. An angle of insonation of sixty degrees is ideal; however, an angle between 30 and 70 is acceptable. J Vasc Surg 1993; 17:578. (B) Duplex ultrasound imaging begins with short-axis views of the subclavian artery obtained, Long-axis subclavian examination. The analogous index in the upper extremity is the wrist-brachial index (WBI). A meta-analysis of 14 studies found that sensitivity and specificity of this technique for 50 percent stenosis or occlusion were 86 and 97 percent for aortoiliac disease and 80 and 98 percent for femoropopliteal disease [42]. A threshold of less than 0.9 is an indication for invasive studies or operative exploration in equivocal cases. Authors 2012;126:2890-2909 JAMA 1993; 270:465. The quality of a B-mode image depends upon the strength of the returning sound waves (echoes). Duplex scanning for diagnosis of aortoiliac and femoropopliteal disease: a prospective study. Sumner DS, Strandness DE Jr. (See 'Transcutaneous oxygen measurements'above. Health care providers calculate ABI by dividing the blood pressure in an artery of the ankle by the blood pressure in an artery of the arm. Nicola SP, Viechtbauer W, Kruidenier LM, et al. Rutherford RB, Baker JD, Ernst C, et al. Monophasic signals must be distinguished from venous signals, which vary with respiration and increase in intensity when the surrounding musculature is compressed (augmentation). A normal arterial Doppler velocity waveform is triphasic with a sharp upstroke, forward flow in systole with a sharp systolic peak, sharp downstroke, reversed flow component at the end of systole, and forward flow in late diastole (picture 5) [43,44]. Indications Many (20-50%) patients with PAD may be asymptomatic but they may also present with limb pain / claudication critical limb ischemia chest pain Procedure Equipment Your doctor uses the blood pressure results to come up with a number called an ankle-brachial index. Resting ABI is the most commonly used measurement for detection of PAD in clinical settings, although variation in measurement protocols may lead to differences in the ABI values obtained. Wrist-brachial index The wrist-brachial index (WBI) is used to identify the level and extent of upper extremity arterial occlusive disease. N Engl J Med 2001; 344:1608. Normal is about 1.1 and less . (See "Screening for lower extremity peripheral artery disease".). InterpretationA normal response to exercise is a slight increase or no change in the ABI compared with baseline. (See 'Physiologic testing'above. (See 'Indications for testing'above. J Vasc Surg 1997; 26:517. or provide information that will alter the course of treatment should be performed. In patients with arterial calcification, such as patients with diabetes, more reliable information is often obtained using toe pressures and calculation of the toe-brachial index, and pulse volume recordings. Patients with diabetes who have medial sclerosis and patients with chronic kidney disease often have nonocclusive pressures with ABIs >1.3, limiting the utility of segmental pressures in these populations. (See 'Ankle-brachial index'above and 'Physiologic testing'above and 'Ultrasound'above and 'Other imaging'above. A four-cuff technique (picture 2) uses two narrower blood pressure cuffs rather than one large cuff on the thigh and permits the differentiation of aortoiliac and superficial femoral artery disease [32]. Vascular Ultrasound case: Upper Extremity Arterial PVR, Segmental Pressures and wrist brachial index interpretation. ABI is measured by dividing the ankle systolic pressure by brachial systolic pressure. The upper extremity arterial system requires a different diagnostic approach than that used in the lower extremity. In this video, taken from our Ultrasound Masterclass: Arteries of the Legs course, you will understand both the audible and analog waveforms of Dopplers, and. (See 'Pulse volume recordings'below.). Pressure measurements are obtained for the radial and ulnar arteries at the wrist and brachial arteries in each extremity. This reduces the blood pressure in the ankle. ProtocolsThere are many protocols for treadmill testing including fixed routines, graded routines and alternative protocols for patients with limited exercise ability [36]. (A) Gray-scale sonography provides a direct view of a stenosis at the origin of the right subclavian artery (, Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), on Assessment of Upper Extremity Arterial Disease, Assessment of Upper Extremity Arterial Disease, Assessment of Upper Extremity Arterial Occlusive Disease, Carotid Occlusion, Unusual Pathologies, and Difficult Carotid Cases, Ultrasound Evaluation Before and After Hemodialysis Access, Extremity Venous Anatomy and Technique for Ultrasound Examination, Doppler Ultrasound of the Mesenteric Vasculature. The right arm shows normal pressures and pulse volume recording (, Hemodynamically significant stenosis. Circulation 1995; 92:720. 0.90); and borderline values defined as 0.91 to 0.99. The ankle brachial index is associated with leg function and physical activity: the Walking and Leg Circulation Study. Higher frequency sound waves provide better lateral resolution compared with lower frequency waves. It then goes on to form the deep palmar arch with the ulnar artery. Subclinical disease as an independent risk factor for cardiovascular disease. Mechanical compression in the thoracic outlet region, vasospasm of the digital arteries, trauma-related thrombi in the hand or wrist, arteritis, and emboli from the heart or from proximal arm aneurysms are pathologies to be considered when evaluating the upper extremity arteries. A 20 mmHg or greater reduction in pressure is indicative of a flow-limiting lesion if the pressure difference is present either between segments along the same leg or when compared with the same level in the opposite leg (ie, right thigh/left thigh, right calf/left calf) (figure 1). Repeat the measurement in the same manner for the other pedal vessel in the ipsilateral extremity and repeat the process in the contralateral lower extremity. Thus, WBIs are typically measured only when the patient has clinical signs or symptoms consistent with upper extremity arterial stenosis or occlusion. It must be understood, however, that normal results of these indirect tests cannot rule out nonobstructive plaque or thrombus, aneurysm, transient mechanical compression of an artery segment, vasospasm, or other pathologies (such as arteritis). With severe disease, the amplitude of the waveform is blunted (picture 3). Why It Is Done Results Current as of: January 10, 2022 Upper extremity segmental pressuresSegmental pressures may also be performed in the upper extremity. ACC/AHA 2005 Practice Guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): a collaborative report from the American Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease): endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society for Vascular Nursing; TransAtlantic Inter-Society Consensus; and Vascular Disease Foundation. Given that interpretation of low flow velocities may be cumbersome in practice, it . Did the pain or discomfort come on suddenly or slowly? It is generally accepted that in the absence of diabetes and tissue edema, wounds are likely to heal if oxygen tension is greater than 40 mmHg. A metaanalysis of eight studies compared continuous versus graded routines in 658 patients in whom testing was repeated several times [. Segmental volume plethysmography in the diagnosis of lower extremity arterial occlusive disease. These articles are written at the 10thto 12thgrade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon. 13.18 ). Decreased ankle/arm blood pressure index and mortality in elderly women. This study aimed to assess the association of high ABPI ( 1.4) with cardiovascular events in people with peripheral artery disease (PAD). 2012 Dec 11;126 (24):2890-909. doi: 10.1161/CIR.0b013e318276fbcb. MEASUREMENT OF WRIST: BRACHIAL INDICES AND ARTERIAL WAVEFORM ANALYSIS, measurement of radial and ulnar (or finger) and brachial arterial pressures bilaterally using Doppler or plethysmographic techniques, the calculation of the wrist (or finger ) brachial systolic pressure indices and assessment of arterial waveforms for the evaluation of upper This index provides a measure of the severity of disease [10]. 22. Eur J Radiol 2004; 50:303. 1. Facial Esthetics. Signs [ edit ] Pallor Diminished pulses (distal to the fistula) Necrosis [1] Decreased wrist- brachial index (ratio of blood pressure measured in the wrist and the blood pressure [en.wikipedia.org] Physical examination findings may include unilaterally decreased pulses on the affected side, a blood pressure difference of greater than 20 mm Hg . Depending upon the clinical scenario, additional testing may include additional physiologic tests, duplex ultrasonography, or other imaging such as angiography using computed tomography or magnetic resonance imaging, or conventional arteriography. Wolf EA Jr, Sumner DS, Strandness DE Jr. The ratio of the velocity of blood at a suspected stenosis to the velocity obtained in a normal portion of the vessel is calculated. The normal value for the WBI is 1.0. Flow toward the transducer is standardized to display as red and flow away from the transducer is blue; the colors are semi-quantitative and do not represent actual arterial or venous flow. The ABI is recorded at rest, one minute after exercise, and every minute thereafter (up to 5 minutes) until it returns to the level of the resting ABI. Note that time to peak is very short, the systolic peak is narrow, and flow is absent in late diastole. Since the absolute amplitude of plethysmographic recordings is influenced by cardiac output and vasomotor tone, interpretation of these measurements should be limited to the comparison of one extremity to the other in the same patient and not between patients. The pitch of the duplex signal changes in proportion to the velocity of the blood with high-pitched harsh sounds indicative of stenosis. Not only are the vessels small, there are numerous anatomic variations. 13.20 , than on the left because the right subclavian artery is a branch of the innominate artery and often has a good imaging window. The National Health and Nutrition Survey (NHANES) estimated that 1.4 percent of adults age >40 years in the United States have an ABI >1.4; this group accounts for approximately 20 percent of all adults with PAD [26]. There are no universally accepted velocity cut points that determine the severity of a stenosis in the arm arteries; however, when a stenosis causes the PSV to double (compared with the prestenotic velocity), it is considered of hemodynamic significance (50% diameter narrowing).