The mean peak systolic velocity in the ECA is reported as being 77 cm/sec in normal individuals, and the maximum velocity does not normally exceed 115 cm/sec. This is most commonly caused by excessive transducer probe pressure, which leads to transient reversal of flow that quickly resolves after readjustment of the probe. Homogeneous or echogenic plaques are believed to be stable and are unlikely to develop intraplaque hemorrhage or ulceration. The normal range of velocities in the carotid branches varies as a function of age. Carotid doppler normal values | HealthTap Online Doctor The ECA waveform has a higher resistance pattern than the ICA. Due to the controversy surrounding the definition of biphasic, there is disagreement about whether biphasic flow is normal 2. The two transition zones between the lumen and the intima and between the media and adventitia produce two parallel echogenic lines, with an intervening zone of low echoes that corresponds to the media. Usually, heart blockage in the moderate range does not cause significant limitation to blood flow and so does not cause symptoms. (2019). Specific recordings were also taken proximal to the stenosis, at the stenosis site, and immediately distal to the stenosis in the ICA, as seen on real-time imaging. Dampened or monophasic waveforms, turbulent color flow imaging, and increased velocities in the region of stenosis are characteristic findings of obstruction. The .gov means its official. (2003) Radiographics : a review publication of the Radiological Society of North America, Inc. 23 (5): 1315-27. As your carotids narrow, the velocity of blood increases. endstream endobj 815 0 obj <. 5. Ultrasound Assessment of Carotid Stenosis | Radiology Key As such, Doppler thresholds taken from studies that did not use the NASCET method of measurement should not be used. Bethesda, MD 20894, Web Policies Velocities in normal radial and ulnar arteries range between 40 and 90 cm/s, whereas velocities within the palmar . In addition, on average, the common carotid blood flow velocity in the low neck is 10 to 20 cm/sec higher than near the bifurcation.11 This observation is of considerable importance, as the measured peak systolic velocity ratio (ICA peak systolic velocity/CCA peak systolic velocity; see Chapter 9) will depend on the location where velocities are sampled in the CCA. Cold cranking amp is abbreviated CCA and cranking amp being abbreviated CA. Normal human peak systolic blood flow velocities vary with age, cardiac output, and anatomic site. At the aortic valve, peak velocities of up to 500 cm/sec may be possible. On a Doppler waveform, the peak systolic velocity corresponds to each tall "peak" in the spectrum window 1. High-grade stenoses exhibit higher peak frequencies associated with opacification of the area under the systolic peak caused by elevated flow velocity and dis- turbed flow. Tortuous segments, kinks, or areas of branching disrupt the normal laminar flow pattern. Triphasic high-resistance waveforms are seen in lower limb arteries as in other peripheral arteries (,Fig 9,). This chapter emphasizes the Doppler evaluation of ICA stenosis because it has been extensively studied and is strongly associated with TIA and stroke. Accessibility Peak systolic velocity (PSV) is an index measured in spectral Doppler ultrasound. EDV was slightly less accurate. Reference ranges for middle cerebral artery peak systolic velocity in In one study, PSV and ICA/CCA PSV ratios performed almost identically with regard to the identification of ICA stenoses greater than 70% when compared with angiography ( Fig. 8600 Rockville Pike Blood flow signals are not as strong as at peak systole. 7.8 ). Typically, a 9-MHz linear transducer (or transducer range of 5 to 12MHz) is used. endstream endobj startxref With surgery, blood flow is rerouted across the blockage using a small plastic tube called a bypass graft. Dr. Jason Sample answered General Surgery 26 years experience Sounds normal: These velocities sound normal. 3. The https:// ensures that you are connecting to the Conversely, blood flow velocities in the ICA contralateral to a high-grade stenosis or occlusion may be higher than expected if the vessel is the major supplier of collateral blood flow around the circle of Willis. official website and that any information you provide is encrypted This is probably related to both a true increase in velocity as blood accelerates around a curve and difficulty in assigning a correct Doppler angle. The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). 24. These are some common normal peak systolic velocities: Peripheral artery stenosis is considered significant when the diameter reduction is 50% or greater, which corresponds to 75% cross sectional area reduction. Off-axis view of the carotid wall. Carotid Ultrasound: An elevated peak systolic velocity (psv) would suggest a narrowing of the carotid artery, however this is only one of the criteria used to determine t. Read More. 2008 Jul;48(1):104-12; discussion 112-3. doi: 10.1016/j.jvs.2008.02.068. ICA velocities decrease with age, reaching typical values between 60 and 90 cm/sec for ages 60 years and above. Optimal carotid duplex velocity criteria for defining the severity of carotid in-stent restenosis. [PSV = peak systolic velocity; EDV = end-diastolic velocity; ICA = internal carotid artery; CCA = common carotid artery] normal. (PDF) Normal Reference Values of Ratios of Blood Flow Velocities in The lumen-intima interface is best seen on longitudinal images when the image plane passes through the center of the artery and the ultrasound beam forms a 90-degree incident angle with the wall interfaces (Figure 7-2; see Video 7-1). The bulb is defined as being the zone of dilatation of the common carotid artery (CCA) to the level of the flow divider (the junction of internal carotid artery [ICA] and external carotid artery [ECA]). There is wide variability in the peak systolic velocities seen in normal patients, with a range of 20 to 60 cm/s, with an even wider range noted at the vertebral artery origin (also called segment V0). Values up to 150 cm/sec can be seen without a significant lesion being present (Figure 7-8). Page 4. Uppal T, Mogra R. RBC motion and the basis of ultrasound Doppler instrumentation. What does Enterococcus faecalis look like? Carotid Sonography: Protocol and Technical Considerations Before What is the function of lamellae in bone? Although this is an appropriate method in most vessels, there are several unique features of the proximal ICA that render this measurement technique problematic. Average peak and mean blood velocities were 66 and 11 cm/sec in the ascending aorta, 57 and 10 cm/sec in the pulmonary artery, 28 and 12 cm/sec in the superior vena cava, and 26 and 13 cm/sec in the inferior vena cava. Di Pino L, Franchina AG, Costa S, Gangi S, Strano F, Ragusa M, Costanzo L, Tamburino C, Capodanno D. Int J Cardiovasc Imaging. 2021 Nov;74(5):1609-1617.e1. Up to 30% of all major hemispheric events (stroke, transient ischemic attacks [TIA], or amaurosis fugax) are thought to originate from disease at the carotid bifurcation. Although the peak systolic velocity in the right ICA is slightly elevated to 130cm per second, there is normal ICA/CCA ratio measuring 0.95. Ultrasound Assessment of Lower Extremity Arteries The SRU criteria were derived from multiple studies reflecting different velocity parameters including the PSV, the ratio of PSV in the ICA to that in the ipsilateral distal CCA (i.e., the ICA PSV/CCA PSV ratio), and end-diastolic velocity (EDV). Would you like email updates of new search results? Moderate (50% to 69%) internal carotid artery (, Receiver Operating Characteristic (ROC) curves for three Doppler velocity measurements to detect 70% or greater internal carotid artery (ICA) stenosis: peak systolic velocity (PSV =, 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 Ultrasound Assessment of Carotid Stenosis, Ultrasound Assessment of Carotid Stenosis, Carotid Sonography: Protocol and Technical Considerations, Normal Findings and Technical Aspects of Carotid Sonography, Ultrasound Assessment of Lower Extremity Arteries, Ultrasound Assessment of the Vertebral Arteries. We provide reference data for the V ICA /V CCA ratios for the peak systolic velocity (PSV), mean velocity (MV), and end-diastolic velocity (EDV) . B, This diagram shows a more typical anatomic definition of the carotid bifurcation. What is the difference between CA and CCA? - Bigtime Battery no, leaving open to variability; the 150 cm/sec addressed later>, likely a reflection of a higher cardiac output. The wall of every artery is composed of three layers: intima, media, and adventitia. Given that the two velocity values are taken from the same vessel involved by the stenosis, Hathout etal. The average PSV in normal volunteers is between 30 and 40 cm/s. However, during the first 16 weeks, a reversal in end-diastolic flow can be a normal finding due to the low resistance arcuate arteries and intervillous spaces not yet being formed. Flow velocity may vary based on vessel properties and pathological changes 3,4. This is caused by too little blood flow to your legs or arms. This consensus developed recommendations for the diagnosis and stratification of ICA stenosis 2. As a result of improved high-resolution ultrasound imaging of the carotid arteries with supplemental imaging from MRA or CTA, the role of conventional angiography as a diagnostic technique has significantly decreased. 7.1 ). The time average of any other quantity can be defined in this manner. 16 (3): 339-46. 141516 The proximal CCA diameter must be multiplied by 1.2 to estimate the diameter of a normal ICA bulb, or a distal disease-free CCA diameter can be taken as a denominator to calculate No external carotid artery stenosis is demonstrated. For ICA/CCA Peak Systolic Velocity ratio, use the highest PSV in the internal carotid artery and . The two transition zones between the lumen and the intima and between the media and adventitia produce two parallel echogenic lines, with an intervening zone of low echoes that corresponds to the media. You usually wont have atherosclerosis symptoms until an artery is so narrowed or clogged that it cant supply enough blood to your organs and tissues. The ICA/CCA PSV ratio was calculated by dividing the PSV of the ICA, which was selected for analysis by the PSV of the CCA. Normal doppler spectrum. The ICA (located inferiorly and to the right) is typically larger than the ECA (located to the left and upward). A 20mmHg pressure difference between right and left extremities denotes disease. Reference article, Radiopaedia.org (Accessed on 01 May 2023) https://doi.org/10.53347/rID-78164. The CCA peak systolic velocity should therefore be obtained before the beginning of the bulb, ideally 2 to 4 cm below. This study proposed the incorporation of distal ICA flow velocity information on the conventional carotid Doppler study improving the diagnostic accuracy of PSV 1. deceleration spectral broadening with a peak systolic velocity (PSV) <125 cm/s, pansystolic spectral broadening with a PSV <125 cm/s, pansystolic spectral broadening with a PSV of >125 cm/sand, end diastolic velocity (EDV) <110 cm/s or ICA/CCA PSV ratio >2 but <4, pansystolic spectral broadening with PSV >270 cm/s, complete occlusion: no flow; terminal thump. Portnova GV, Maslennikova AV, Proskurnina EV. high CCA: Waveforms in the common carotid artery close to the bifurcation show moderately broad systolic peaks and a moderate amount of blood flow throughout diastole. Normal reference values of ratios of blood flow velocities in internal On a Doppler waveform, the peak systolic velocity corresponds to each tall peak in the spectrum window 1. Summary. [PSV = peak systolic velocity;EDV = end-diastolic velocity; ICA = internal carotid artery; CCA = common carotid artery], ICA PSV is <125 cm/sec and no plaque or intimal thickening is visible sonographically, additional criteria include ICA/CCA PSV ratio <2.0 and ICA EDV <40 cm/sec, ICA PSV is <125 cm/sec and plaque or intimal thickening is visible sonographically, ICA PSV is 125-230 cm/sec and plaque is visible sonographically, additional criteria include ICA/CCA PSV ratio of 2.0-4.0 and ICA EDV of 40-100 cm/sec, 70% ICA stenosis but less than near occlusion, ICA PSV is >230 cm/sec and visible plaque and luminal narrowing are seen at gray-scale and color Doppler ultrasound (the higher the Doppler parameters lie above the threshold of 230 cm/sec, the greater the likelihood of severe disease), additional criteria include ICA/CCA PSV ratio >4 and ICA EDV >100 cm/sec, velocity parameters may not apply, since velocities may be high, low, or undetectable, diagnosis is established primarily by demonstrating a markedly narrowed lumen at color or power Doppler ultrasound, no detectable patent lumen at gray-scale ultrasound and no flow with spectral, power, and color Doppler ultrasound, there may be compensatory increased velocity in the contralateral carotid. AREDV in the umbilical artery is associated with intraventricular hemorrhage, bronchopulmonary dysplasia, and perinatal mortality. We compared the performance of two independent laboratories using similar equipment (ATL-HDI Ultramark 9 . Normal CCA and ICA Images. 1. . during systole), red blood cells exhibit their greatest magnitude of Doppler shift. Eighty-five patients (average age, 59 years) with normal ICAs and CCAs formed the cohort for this study. What is the ICD-10-CM code for skin rash. The intimal reflection should be straight, thin, and parallel to the adventitial layer. The normal range of the ICA/CCA ratio was defined in 2966 symptomatic or contralateral carotid arteries with 0% to 49% stenosis. velocity ratio (ICA peak systolic velocity/CCA peak systolic velocity; see Chapter 9) will depend on the location where velocities are sampled in the CCA. PVR Waveform Interpretation: A decrease of 20mmHg in pressure between adjacent levels of the ipsilateral extremity denotes disease. Duplex ultrasound velocity criteria for the stented carotid artery. The innermost layer abutting the lumen is the. The carotid sinus, also known as the carotid bulb, is a neurovascular structure that appears as a dilation at the bifurcation of the common carotid artery, and the beginning of the internal carotid artery. Diagnostic algorithm implementing the inter-common carotid artery ( CCA) peak systolic velocity ( PSV) ratio in the vascular laboratory. On the left, there is no elevation of peak systolic velocity with a normal ICA/CCA ratio of 0.84. Carotid artery duplex velocity criteria might be equivocal after left ventricular assist device implantation. The stenosis PSV to pre-stenotic PSV is 2.0 or greater. The peak systolic velocity is more than double the velocity in the proximal segment. These elevated velocities, are also associated with different degrees of coiling of the artery ultimately leading to kinking. BU-902a: How to Measure CCA - Battery University Although the commonly used PSV ratio (ICA PSV/CCA PSV) performs well, the denominator is obtained from the CCA, which can potentially be affected by extraneous factors such as disease in the CCAs and/or the ECAs. With ACAS and NASCET, the degree of stenosis is measured by relating the residual lumen diameter at the stenosis to the diameter of the distal ICA. Stenoses of the external carotid artery (ECA) are not considered clinically important but should be reported because they may explain the presence of a bruit on clinical examination and need to be considered by the surgeon at the time of carotid endarterectomy (CEA). Reference article, Radiopaedia.org (Accessed on 01 May 2023) https://doi.org/10.53347/rID-9404. The ICA and ECA can be distinguished by the low-resistance waveforms (higher diastolic flow) in the ICA as compared with the high-resistance waveforms in the ECA (lower diastolic flow) ( Fig. Ability to use duplex US to quantify internal carotid stenoses: fact or fiction? The definition of peak systolic velocity varies between examiners when spectral broadening due to turbulence is present. Common carotid artery peak systolic velocity ratio predicts - PubMed View Patrick O'Shea's current disclosures, see full revision history and disclosures, Factors that influence flow velocity indices, fetal middle cerebral arterial peak systolic velocity, end-diastolic velocity (Doppler ultrasound), iodinated contrast media adverse reactions, iodinated contrast-induced thyrotoxicosis, diffusion tensor imaging and fiber tractography, fluid attenuation inversion recovery (FLAIR), turbo inversion recovery magnitude (TIRM), dynamic susceptibility contrast (DSC) MR perfusion, dynamic contrast enhanced (DCE) MR perfusion, arterial spin labeling (ASL) MR perfusion, intravascular (blood pool) MRI contrast agents, single photon emission computed tomography (SPECT), F-18 2-(1-{6-[(2-[fluorine-18]fluoroethyl)(methyl)amino]-2-naphthyl}-ethylidene)malononitrile, chemical exchange saturation transfer (CEST), electron paramagnetic resonance imaging (EPR). Arteries with 70% to 99% symptomatic stenosis and an ICA/CCA ratio below this range were categorized as narrowed. Other studies, both here and abroad, confirmed the benefit of CEA and validated the role of this procedure. 2021 Jul 31;43:18-23. doi: 10.1016/j.athplu.2021.07.020. The degree to which the carotid arteries widen at the carotid bulb varies from one individual to another. Example of Sensitivity and Specificity for Internal Carotid Artery Peak Systolic Velocity Cut Points Corresponding to a 70% Diameter Stenosis. What is normal peak systolic velocity of internal carotid artery? In normal common carotid arteries that are relatively straight, blood flow is, velocities near the vessel wall and faster velocities near the center. 7.1 ). What is CCA prox? Check for errors and try again. What does CM's mean on ultrasound? How do you calculate ICA CCA ratio? - Studybuff As we age, hypertension and small injuries to the blood vessel wall can allow plaque to build up. Sonographic NASCET index: a new doppler parameter for assessment of internal carotid artery stenosis. With the advent of statin (HMG-CoA reductase inhibitors) therapy, studies demonstrated a decreased risk of major vascular events such as stroke and that more aggressive statin treatment further decreased that risk by an additional 16%. Grading Carotid Stenosis With Ultrasound | Stroke Carotid artery stenosis: gray-scale and Doppler US diagnosis-Society of Radiologists in Ultrasound Consensus Conference. The diagnostic strata proposed by the Consensus Conference of the SRU (0% to 49%, 50% to 69%, and 70% but less than near occlusion) represent practical values that are clinically relevant and consistent with the NASCET. There is normal antegrade . Carotid Bifurcation. Considerable patient-to-patient variability occurs in ECA flow velocity in normal individuals because pulsatility varies considerably from one person to another since some individuals have a sharply spiked systolic peak, while others have a more blunted peak. 4. Review of Arterial Vascular Ultrasound. Normal healthy arteries are flexible and have smooth inner walls. ICA: The ICA waveforms have broad systolic peaks and a large amount of flow throughout diastole. Peak systolic velocity (Doppler ultrasound) - Radiopaedia The ascending aorta has the highest average peak velocities of the major vessels; typical values are 150-175 cm/sec. Grading carotid stenosis using ultrasonic methods. The NASCET (North American Symptomatic Carotid Endarterectomy Trial) demonstrated that CEA resulted in an absolute reduction of 17% in stroke at 2 years when compared with medical therapy in symptomatic patients with 70% or greater stenosis. The outermost echogenic (white) area is the adventitia of the artery. The peak systolic velocity is increased 30% to 100% compared with the adjacent proximal segment. To decrease interobserver error, the NASCET and ACAS investigators adopted a different method: comparing the smallest residual luminal diameter with the luminal diameter of the normal ICA distal to the stenosis ( Fig. For that reason, ICA/CCA PSV ratio measurements may identify patients who, for hemodynamic reasons (e.g., low cardiac output, tandem lesions), have velocities that fall outside the expected norm for either PSV or EDV. 17 In every case, the sample gate in the ICA was positioned at the point of the maximum velocity change. The carotid bulb spans the junction of the internal and external carotid arteries and blends into the dilatation of the sinus along the lateral aspect (opposite the flow divider) of the proximal ICA. The lines define the location where IMT measurements are made in one of the protocols used in epidemiologic studies. Reappraisal of velocity criteria for carotid bulb/internal carotid artery stenosis utilizing high-resolution B-mode ultrasound validated with computed tomography angiography. Methods: Patients who underwent both carotid ultrasonography and cerebral angiography during hospitalization were consecutively and retrospectively enrolled. ICA = internal carotid artery. (2013) Interactive cardiovascular and thoracic surgery. J. Vasc. Radiology. The carotid ultrasound examination begins with the patient supine and neck slightly extended with the head turned to the opposite side if needed ( Fig. Therefore one should always consider the gray-scale and color Doppler appearance of the carotid segment in question including the plaque burden and visual estimates of vessel narrowing to determine whether all diagnostic features (both visual and velocity data) of a suspected stenosis are concordant. Triphasic arterial flow is considered normal in peripheral arteries and monophasic flow is considered abnormal 7. Although the so-called NASCET method may not truly reflect the degree of luminal narrowing at the site of stenosis, this method has the advantage of minimizing interobserver error. Purpose: Assessment of Upper Extremity Arterial Disease | Radiology Key Ultrasound assessment of carotid arterial atherosclerotic disease. A, This transverse video shows the zone of flow reversal (blue; arrow) in the proximal internal carotid artery (ICA) at peak systole. At the time the article was created Yuranga Weerakkody had no recorded disclosures. It should be noted that the ECST continued to rely on the conventional method of stenosis measurement, and, although both the original NASCET and ECST confirmed the effectiveness of CEA, their methods of measuring ICA stenosis were quite different. Quantitative vascular measurements in arterial occlusive disease. Hence, if the ICA is extremely tortuous, caution is required when making the diagnosis of a stenosis on the basis of increased Doppler velocities alone without observing narrowing of the vessel lumen on gray-scale and/or color flow imaging and showing poststenotic turbulence on the Doppler spectral tracing. The CCA peak systolic velocity should therefore be obtained before the beginning of the bulb, ideally 2 to 4 cm below. The normal range of the ICA/CCA ratio was defined in 2966 symptomatic or contralateral carotid arteries with 0% to 49% stenosis. ICA velocities decrease with age, reaching typical values between 60 and 90 cm/sec for ages 60 years and above.9,10 Blood flow velocities vary with physiologic state of the individual, being higher with exercise than at rest. 2008 Jan;47(1):63-73. doi: 10.1016/j.jvs.2007.09.038. The CCA shares the appearance of both waveforms. Materials and methods: Normal Doppler waveforms of 24 CCA from 12 healthy individuals of age 22-28. The upper reference limit for the ratio can serve as an aid in the more specific identification of patients with minor or mild ICA narrowing. High-resistance spectral waveforms are characterized by velocities that increase sharply with systole, decrease rapidly with the cessation of ventricular contraction, and show little or no forward flow during diastole (Fig. The normal (triphasic) Doppler velocity waveform is made up of three components which correspond to different phases of arterial flow: rapid antegrade flow reaching a peak during systole, transient reversal of flow during early diastole, and slow antegrade flow during late diastole. Graduated from ENSAT (national agronomic school of Toulouse) in plant sciences in 2018, I pursued a CIFRE doctorate under contract with SunAgri and INRAE in Avignon between 2019 and 2022. 7.7 ). High flow velocity causes Reynolds number to increase beyond a critical point, resulting in turbulent flow which manifests as spectral broadeningon Doppler ultrasound 3. Fourier transform and Nyquist sampling theorem. 4. Blood flow velocities can therefore be artificially elevated as the blood flows into and out of the curved segment. Graduated from ENSAT (national agronomic school of Toulouse) in plant sciences in 2018, I pursued a CIFRE doctorate under contract with SunAgri and INRAE in Avignon between 2019 and 2022. The difference in these two ratings are cold cranking amp is measured at -17.8 degrees Celsius and cranking amp is measured at 0 degrees Celsius. Elevated velocities can also be found with entities other than significant stenosis such as in young athletes, in high cardiac output states, in vessels supplying arteriovenous fistulas or arterial venous malformations, and in patients with carotid stenting. Bookshelf (C) Spectral Doppler suggests a 50% to 69% stenosis based on mildly elevated peak-systolic velocity ( PSV = 139 cm/s) and end diastolic velocity ( EVD = 60 cm/s). [PSV = peak systolic velocity ; EDV = end-diastolic velocity; ICA = internal carotid artery; CCA = common carotid artery] normal ICA PSV is <125 cm/sec and no plaque or intimal thickening is visible sonographically additional criteria include ICA/CCA PSV ratio <2.0 and ICA EDV <40 cm/sec <50% ICA stenosis Examples of a classification of carotid kinks, Carotid Sonography: Protocol and Technical Considerations, Ultrasound Assessment of the Abdominal Aorta, Ultrasound Assessment of Carotid Stenosis, Hemodynamic Considerations in Peripheral Vascular and Cerebrovascular Disease, Introduction to Vascular Ultrasonography Expert Consult - Online. A PSV of 35 cm/s is unequivocally normal, whilst a PSV of <25 cm/s following adequate stimulation indicates definite arterial insufficiency. We provide reference data for the V(ICA)/V(CCA) ratios for the peak systolic velocity (PSV), mean velocity (MV), and end-diastolic velocity (EDV) measured in a large group of healthy subjects. 5. 19 (2): 83-90. FIGURE 7-6 Normal carotid artery Doppler waveforms. PSV is by far the most commonly used parameter because it is easily obtained and highly reproducible. The velocity criteria apply when atherosclerotic plaque is present and their accuracy can be affected by: ICA/CCA PSV ratio measurements may identify patients that for hemodynamic reasons (low cardiac output, tandem lesions, etc. Since the ultrasound transducer typically measures 4 cm, it can be used to help locate this point by placing one end at the level of the bulb and sampling at the mid transducer, or approximately 2 cm below the beginning of the bulb. Epub 2021 May 3. Clipboard, Search History, and several other advanced features are temporarily unavailable. In general, for a given diameter of a residual lumen, the calculation of percent stenosis tends to be significantly higher using the pre-NASCET measurement method when compared with the NASCET method ( Fig. . Hathout etal. In stenosis, a localized reduction in vascular radius increases resistance, causing increased PSV and EDV distal to the stenosed site 3,4. J Vasc Surg. 2012;43 (3): 916-21. Peak systolic ICA velocities as high as 120 cm/sec have been reported in some normal adults, but these values are exceptional, and an ICA velocity exceeding 100 cm/sec should be viewed as potentially abnormal in older individuals.
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