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2023 European Society of Cardiology. Flow velocity . This is more often seen on the left side. [8] In contrast to what is observed in the vasculature, hydroxyapatite deposition and leaflet infiltration are the main mechanisms for leaflet restriction and haemodynamic obstruction. This artery segment is typically quite straight, with minimal tortuosity and does not have any significant diameter changes. Is 50 blockage in carotid artery bad? Subaortic stenosis produces a high-velocity jet and a mean transvalvular pressure gradient (TMPG), and LVOT systolic blood flow disorder forms rich and complex vortex dynamics . Aortic valve calcium scoring is a quantitative and flow-independent method of assessing AS severity (recommended thresholds are 2,000 in men and 1,250 in women). It has been shown that peak systolic velocity decreases as the distance from the circle of Willis increases. 2010). Occasionally (in 3% to 5% of cases) the left vertebral artery has its origin from the aorta and not from the left subclavian artery. Average PSV clearly increases with increasing severity of angiographically determined stenosis. Uncertainties regarding incidence and outcome of these patients are the consequence of the use of a different nosology between papers and possibly error measurements. Patients on the left part of the figure are easily classified as severe AS, whereas rest echocardiography remains inconclusive in the other two groups, namely patients with low gradient and normal or low flow. Kamperidis V., van Rosendael P. J., Katsanos S., van der Kley F., Regeer M., Al Amri I., Sianos G., Marsan N. A., Delgado V., & Bax J. J. Messika-Zeitoun D., Aubry M. C., Detaint D., Bielak L. F., Peyser P. A., Sheedy P. F., Turner S. T., Breen J. F., Scott C., Tajik A. J., & Enriquez-Sarano M. Cueff C., Serfaty J. M., Cimadevilla C., Laissy J P., Himbert D., Tubach F., Duval X., Lung B., Enriquez-Sarano M., Vahanian A., & Messika-Zeitoun D. Aggarwal S. R., Clavel M. A., Messika-Zeitoun D., Cueff C., Malouf J., Araoz P. A., Mankad R., Michelena H., Vahanian A., & Enriquez-Sarano M. Simard L., Cote N., Dagenais F., Mathieu P., Couture C., Trahan S., Bosse Y., Mohammadi S., Page S., Joubert P., & Clavel M. A. Clavel M. A., Messika-Zeitoun D., Pibarot P., Aggarwal S. R., Malouf J., Araoz P. A., Michelena H. I., Cueff C., Larose E., Capoulade R., Vahanian A., & Enriquez-Sarano M. Baumgartner H., Falk V., Bax J. J., De Bonis M., Hamm C., Holm P. J., Lung B., Lancellotti P., Lansac E., Munoz D. R., Rosenhek R., Sjogren J., Tornos Mas P., Vahanian A., Walther T., Wendler O., Windecker S., & Zamorano J. L. Bichat Hospital and University Paris VII, Paris, France; Barts Heart Centre, St. Bartholomews Hospital, West Smithfield, London,United Kingdom. Modified from Grant EG, Benson CB, Moneta GL, etal. Prior to the 1990s, the degree of carotid stenosis was measured by angiography and estimated where the artery wall should be so that the local or relative degree of stenosis can be estimated. On the left, there is no elevation of peak systolic velocity with a normal ICA/CCA ratio of 0.84. Therefore, the best way to address this issue is to use a quantitative and reliable flow-independent method for the assessment of AS severity, which is the remarkable characteristic of calcium scoring. Guy Lloyd: speaking engagements and advisory boards, Edwards, Philips, GE. [6] Among 1,704 patients with a valve area below 1 cm, 24% presented with discordant grading (AVA <1 cm and MPG <40 mmHg). Although ultrasound evaluation of the vertebral arteries is recognized as a routine part of the extracranial cerebrovascular examination by various accrediting organizations, this assessment is typically limited to documenting the absence, presence, and direction of blood flow. Sex differences in aortic valve calcification measured by multidetector computed tomography in aortic stenosis. Pulsatility is important to maintain blood flow around another stenotic or occluded vessel 7. With the use of computed tomography in the workup evaluation before TAVI, the anatomy of the aortic annulus has been well described. We will not discuss the assessment of AS severity in patients with depressed ejection, but will focus on patients with normal/preserved ejection fraction. We have shown that calcium scoring is highly correlated to echocardiographic haemodynamic severity and have validated its diagnostic value for the diagnosis of severe AS. 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. Transversely, the CCA is imaged from its proximal to distal aspects with gray-scale and color Doppler imaging. The identification of carotid artery stenosis is the most common indication for cerebrovascular ultrasound. Elevated peak systolic velocity at the stenosis with pansystolic spectral broadening. The proposed threshold of 35 ml/m is now widely accepted, even if its validation has never been carried out properly. The majority of stenotic lesions occur in the proximal internal carotid artery (ICA); however, other sites of involvement in the carotid system may or may not contribute to significant neurologic events. Large, multicenter trials both in North America and Europe confirmed the effectiveness of CEA in preventing stroke in patients with ICA stenoses compared with optimized medical therapy. showed the best accuracy for a 50% stenosis using a cut point of 140cm/s, but did confirm the high accuracy of a peak systolic velocity ratio of 2.0. showed that this method produced superior results in characterizing the degree of ICA stenosis when compared with more commonly applied Doppler parameters. Thus, it is expected that the AVA will increase and the number of patients with MPG <40 mmHg and AVA <1 cm will mathematically decrease. Additional intrarenal scanning permits the diagnosis of RAS without direct imaging of the main renal artery. However, Hua etal. This is why some have suggested combining CT (for the measurement of the LVOT area) and echocardiography for LVOT and aortic TVI in the calculation of the AVA. Measurement of aortic valve calcification using multislice computed tomography: correlation with haemodynamic severity of aortic stenosis and clinical implication for patients with low ejection fraction. It is also possible to collect imaging and Doppler waveforms from the origin of the right vertebral artery in more than 92% to 94% of patients and from the origin of the left vertebral artery in approximately 60% to 86% of patients. Transcranial Doppler (TCD) can be significant in the prevention of stroke under this condition. Each bin represents an average of PSV values over a 10% stenosis range (i.e., the 45% point represents the average between 40% and 50% stenosis). Systolic BP of 180 or higher means that you're in hypertensive crisis and should call your healthcare provider right away. Trials combining CEA with statin therapy started on hospital admission for surgery showed a decrease in neurologic events such as ischemic stroke and decreased mortality after CEA. However, the gray-scale image will typically show the walls of the vertebral artery. Discordant grading is defined either by an AVA <1 cm while MPG is 40 mmHg/PVel <4 m/sec, or by an AVA 1 cm and an MPG 40 mmHg/PVel 4 m/sec, the first situation being much more common. The side-to-side ratio was calculated by dividing contralateral flow parameter by ipsilateral one measured by using carotid ultrasonography. It is the interval between the onset of flow and peak flow. In the coronal plane, a heel-toe maneuver is used to image the CCA from the supraclavicular notch to the angle of the mandible. 7.1 ). The peak-systolic and end-diastolic velocities ranged from 36 to 74 cdsec (mean, 55 cmlsec) and 10 to 25 cdsec (mean, 16 cm/sec), respectively (Table 1). Changes that affect blood velocity like hypertension, pregnancy, overactive thyroid, infection etc could affect the results to a certain extent. LVOT diameter should be measured in the parasternal long-axis view, using the zoom mode, in mid systole and repeated at least three to five times. For 70% ICA stenosis or greater, but less than near occlusion: An internal to common carotid PSV ratio 4.0. Peak systolic velocity in the right renal artery is 173 and the left is 178. Calcium scoring measurements and the above-mentioned thresholds have recently been implemented in the latest version of the ESC/EACTS guidelines on valvular heart disease. Peak systolic velocity (PSV) of the basal segments of the left ventricle from TDI is a robust and user independent parameter. [7] Although attractive, such methodology suffers from important bias. In addition, when statins were started on asymptomatic patients prior to CEA, the incidence of perioperative stroke and early cognitive decline also decreased. More specifically, CT has clearly demonstrated that the LVOT and the aortic annulus are not circular but oval. Normal doppler spectrum. Usefulness of the right parasternal view and non-imaging continuous-wave Doppler transducer for the evaluation of the severity of aortic stenosis in the modern area. what does elevated peak systolic velocity mean. 7. 9.4 . This study will define the optimal Doppler-derived peak systolic velocity (PSV) and velocity ratio (VR) to identify >50% lesions in arteriovenous fistulas (AVF) and arteriovenous grafts (AVG). 9.5 ), using combined gray-scale and color Doppler imaging, to assess blood flow hemodynamics in the proximal artery segment. The ascending aorta has the highest average peak velocities of the major vessels; typical values are 150-175 cm/sec. [10] Interestingly, thresholds for severe AS were different between females and males. As threshold levels are raised, sensitivity gradually decreases while specificity increases. With the improvement in echocardiographic systems and combined two-dimensional/Doppler probe, the crystal probe tends to be disused and may appear outdated. (Reprinted with permission from the Radiological Society of North America: Grant EG, Duerinckx AJ, El Saden S, etal. 8 . Peak systolic velocity (PSV) is an index measured in spectral Doppler ultrasound. Up to 60% of patients have a dominant vertebral artery (i.e., with a larger diameter and higher blood flow velocity than the contralateral side [see Fig. Peak systolic velocities Prior to intervention the PSV ECA in both groups was similar, 161.7 cm/s (CAS) versus 150.9 cm/s (CEA). Evaluation and clinical implications of aortic valve calcification by electron beam computed tomography. It is a cylindrical mechanical device which is placed over the penis and pumped; consequently, it creates a negative pressure vacuum to draw blood into the penis. Sex-Related Discordance Between Aortic Valve Calcification and Hemodynamic Severity of Aortic Stenosis: Is Valvular Fibrosis the Explanation? Peak systolic velocity ranged from 1.2 to 3.3 cm/s, and peak diastolic velocity ranged from 1.6 to 4.5 cm/s. Prognosis of the Four Subsets as Defined in Figure 1. Example of Sensitivity and Specificity for Internal Carotid Artery Peak Systolic Velocity Cut Points Corresponding to a 70% Diameter Stenosis. a. pressure is the highest at the carotid . If the velocity is not dampened that strengthens the chance that the second finding is real. Although the surgical treatment of vertebral artery disease can be successful and relatively safe, patient selection may require consideration of internal carotid artery disease because symptoms of posterior circulation ischemia frequently improve following carotid artery endarterectomy or reconstruction. The human cardiovascular system (CVS) undergoes severe haemodynamic alterations when experiencing orthostatic stress [1,2], that is when a subject either stands up, sits or is tilted head-up from supine on a rotating table.Among the most widely observed responses, clinical trials have shown accelerated heart rhythm and reduced circulating blood volume (cardiac output . Patients often present with nonlocalizing symptoms such as blurred vision, ataxia, vertigo, syncope, or generalized extremity weakness. In addition, ulcerated plaque that demonstrates a focal depression or break within the plaque is also more prone to plaque rupture and subsequent embolic event ( Fig. showed that, in most patients, the systolic velocity decreases in the CCA as one goes from proximal to distal within the vessel. 7.2 ). Other studies, both here and abroad, confirmed the benefit of CEA and validated the role of this procedure. Elevated blood flow velocities in the ECA are not considered clinically important except that they can explain the presence of a clinically detected carotid bruit. 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. N 26 The spectral Doppler system utilizes Fourier analysis and the Doppler equation to convert this shift into an equivalently large velocity, which appears in the velocity tracing as a peak2. Dexmedetomidine (DXM) is a sedative, muscular relaxant, and analgesic drug in common use in veterinary medicine. 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. If the Doppler sample is positioned too far from the aortic orifice, it will be responsible for an overestimation of AS severity. [11] For the same degree of aortic valve calcification, females experienced a higher haemodynamic obstruction or, put another way, a mean gradient of 40 mmHg is associated with a lower calcium load in females than in males. be assessed by phase-contrast determination of peak systolic velocity combined with the modified Bernoulli equation [85]. 9.1 ). The ultrasound examination is the first line imaging study for patients undergoing evaluation for carotid stenosis. Intervention is recommended in symptomatic patients with proven severe AS, as in classic severe AS. Aortic Stenosis Grades of Severity as Assessed Using Echocardiography and Computed Tomography (calcium scoring). Vertebral artery dissection is not commonly associated with elevated blood flow velocities in the absence of significant narrowing in either the true or the false lumen ( Fig. It is important to keep in mind that BSA correction should be only undertaken in patients with small and large stature (small, elderly lady or male, professional basketball player), and should be avoided in those who are obese. The SRU panel concluded that elevated PSV in the ICA and the presence of flow-limiting plaque are the primary parameters determining the severity of ICA stenosis. The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) comparing CAS with CEA demonstrated a similar reduction in stroke between the two procedures in symptomatic and asymptomatic patients. Diastolic flow augmentation may represent a novel target for development of reperfusion therapies. Duplex ultrasound has been shown to be an effective noninvasive technique for the evaluation of the extracranial segments of the vertebral arteries. Mean of maximum cerebral velocity readings are obtained, and results are classified . Using semi-automatic software, areas that are considered as calcification (defined by a tissue density >130 Hounsfield units) are highlighted in red. The estimation of the original lumen is further complicated by the presence of a normal, but highly variable, region of dilatation, the carotid bulb. ), have velocities that fall outside the expected norm for either PSV or EDV. PVel and MPG are obtained on the same image acquisition. In contrast, in the SEAS trial [5], the authors considered the discordance between AVA and MPG independently of any flow consideration. A peak systolic velocity of 2.5 m/s or greater is indicative of a significant stenosis. 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). The diagnosis of stenotic disease affecting other parts of the carotid system may be clinically important and will also be discussed. Symptoms and Signs of Posterior Circulation Ischemia. The more reliable approach to assessing the vertebral artery is to visualize it near the mid portion of the cervical spine, at the V2 segment of the vertebral artery, as it courses cranially through the foramina to the transverse processes of C 6 to C 2 ( 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. LVOT, as with any anatomic structure, is correlated to body size. Thus, in the rest of the article we will use the MPG. 7.3 ). Most of the large carotid stenosis studies compared ultrasound with angiography as the gold standard while using the traditional non-NASCET method of grading carotid stenosis. Longitudinal gray-scale image of a normal vertebral artery segment (, Color Doppler image from the V2 segment of a normal vertebral artery and vein, with the artery color coded red (flow from right to left, toward the brain) and the vertebral vein color coded blue. As expected, computed tomography and calcium scoring accurately classified patients with concordant grading, but more importantly 50% of the patients with discordant grading could be considered as having true severe AS, whereas 50% did not fulfil the criteria for severe AS, irrespective of flow calculation. From these, the ICA/CCA ratio can be automatically calculated, typically with the PSV measurement from the distal CCA in the ratio, because velocity measurements in the proximal CCA may be slightly elevated because of the proximity of the thoracic aorta. All three parameters are consistent with a 70% or greater stenosis according to the Society of Radiologists in Ultrasound (SRU) consensus criteria. The fact that discordant grading is common and that low flow is rare but impacts on prognosis is of no help in assessing whether these patients truly presented severe AS. Further cranially, the V4 vertebral artery segment (extending from the point of perforation of the dura to the origin of the basilar artery) may be interrogated using a suboccipital approach and transcranial Doppler techniques (see Chapter 10 ), but segment V3 (the segment that extends from the arterys exit at C 2 to its entrance into the spinal canal) is generally inaccessible to duplex ultrasound during an extracranial cerebrovascular examination. 7.1 ). An important technical point to be made when calculating the ICA/CCA PSV ratio is that the denominator must be obtained from the distal CCA approximately 2 to 4cm proximal to the bifurcation. In contrast, if positioned too close, within the flow acceleration, it will be responsible for an underestimation of AS severity. 13 (1): 32-34. Our mission: To reduce the burden of cardiovascular disease. It would therefore seem logical to begin the duplex ultrasound examination in this segment. At the time the article was created Patrick O'Shea had no recorded disclosures. However, the peak systolic velocity can vary between 41 and 64cm/s ( Table 9.2 ). 9.2 ). Results: Maximum hemodynamic condition does not necessarily occurred at peak systole . Mitral E/A ratio The ratio between the E-wave and the A-wave is the E/A ratio. The ratio on the right is 1.6 between the renal artery and the aorta and the left is 1.8. The E-wave becomes smaller and the A-wave becomes larger with age. Unable to process the form. Because of tortuosity, nonlaminar blood flow is commonly seen in the proximal vertebral artery, and kinking of the vessel may occur, causing an elevated peak systolic velocity. Second, the prognostic value of the AVA has been established using echocardiographic evaluation, while the prognostic value of combined AVA calculation is uncertain. Hathout etal. (2010) Australasian journal of ultrasound in medicine. Specific cut-points based on the arteriographic correlative studies need to use the NASCET/ACAS measurement approach ( Fig. Given that the two velocity values are taken from the same vessel involved by the stenosis, Hathout etal. Visible narrowing on a color Doppler image accompanied by high-velocity color Doppler aliasing and poststenotic flow patterns are indicative of vertebral artery stenosis. 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). It is also worth noting that the proposed thresholds are not 'magic numbers', but provide a probability of having or not having severe AS. 7.8 ). We identified 622 patients with isolated, asymptomatic AS and peak systolic velocity > or =4 m/s by Doppler echocardiography who did not undergo surgery at the initial evaluation and obtained . In the SILICOFCM project, a . The carotid ultrasound examination begins with the patient supine and neck slightly extended with the head turned to the opposite side if needed ( Fig. 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. 7.5 and 7.6 ). Hypertension Stage 1 In this setting, a significant reduction in post-stenotic flow velocity is termed trickle flow 5. Peak systolic velocity ( PSV ) exceeds 317 cm/s. 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. This is similar to a 114cm/s cut point proposed by Koch etal. Thresholds adjusted to height are currently missing. The former study used the traditional method of grading stenosis, whereas the latter used the NASCET/ACAS approach. What could cause peak systolic velocity of right internal carotid artery to be elevated to 130cm/s but no elevation in left ica & no stenosis found? Multivariable linear and logistic regression were used to evaluate the relationship of cognitive function with carotid flow velocities and BP. Plaque with strong echolucent elements is generally termed heterogeneous plaque, which is considered unstable and more prone to embolize. . The most commonly used obstetrical applications are the peak systolic frequency shift to end-diastolic frequency shift ratio, (S/D) and the resistance index (RI), which represents the difference between the peak systolic and end-diastolic shift divided by the peak systolic shift. Our understanding of the literature is that flow is a prognostic factor, whatever the reason or the cause of the depressed flow. Of note, the rare cases of discordant grading with an AVA >1 cm and an MPG >40 mmHg are often observed in patients with a bicuspid aortic valve and a large LVOT/annulus size. Prof. David Messika-Zeitoun , Intervention is recommended in symptomatic patients with proven severe AS and low gradient, as for patients with classic severe AS. Peak systolic velocity (Figure 4) increased with advancing gestational age. 7.1 ). The right kidney is 12.2cm in length, the left kidney is 12.3cm. 4. Review of Arterial Vascular Ultrasound. NB: If the stenosis is short, there can be a return to triphasic flow dependant on the ingoing flow and quality of the vessels. A historical end-diastolic cut-point PSV 140cm/s derived from the University of Washington criteria is still used for the presence of 80% stenosis despite the fact that the threshold was measured on non-NASCET graded arteriograms. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. 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. The difficulty in estimating the exact location of the plaque-free lumen of the proximal ICA introduced a great degree of interobserver error in estimating the degree of ICA stenosis. The current management of carotid atherosclerotic disease: who, when and how?. The current parameters used to grade the severity of ICA stenosis are based on the Society of Radiologists in Ultrasound (SRU) Consensus Statement in 2003. Size-adjusted left ventricular outflow tract diameter reference values: a safeguard for the evaluation of the severity of aortic stenosis. A normal sized aorta has a valve area of approximately 3.0cm2 (3.0 centimeters squared) and 4.0cm2. The NASCET technique is currently the standard on which the large clinical North American studies were based and should be used to make clinical decisions about which patients undergo CEA. Heart failure patients with low cardiac output are known to have poor cardiovascular outcomes. Discordant grading is defined based upon the observation that one parameter suggests a moderate AS while the other suggests a severe AS. In stepwise selection of polynomial terms, the linear, quadratic, and cubic correlations of .38, .17, and .22 for N and .45, .24, and .03 for C were found to be significant ( P <.02). It is critical to underline that a 1 mm change in measurement of the LVOT diameter results in 0.1 cm difference in AVA calculation. By the Doppler equation, it is noted that the magnitude of the Doppler shiftis proportional to the cosine of the angle (of insonation) formed between the ultrasound beam and the axis of blood flow 2. At the aortic valve, peak velocities of up to 500 cm/sec may be possible. where they found a ratio of 2.2 to have the best accuracy for stenosis of 50% or more. (2003) Radiographics : a review publication of the Radiological Society of North America, Inc. 23 (5): 1315-27. A precise evaluation of the severity of aortic valve stenosis (AS) is crucial for patient management and risk stratification, and to allocate symptoms legitimately to the valvular disease. If calcium scoring is below the threshold, AS is more likely to be non-severe and probably conservatively managed, although whether an intervention may provide a benefit still needs to be evaluated. Medical Information Search 9.10 ). In the 1990s, many large, well-controlled, multicenter trials both in North America and Europe confirmed the effectiveness of CEA in preventing stroke in patients with ICA stenoses as compared with optimized medical therapy. There is no obvious cut point to indicate an ideal threshold. Similar cut-points had also been validated against angiography and produced a sensitivity of 95.3% and specificity of 84.4%. Fulfilling the precise and rigorous methodology presented above, the rate of patients with discordant grading is still between 20% and 30%, thus representing a common clinical problem. Velocities higher than 180 cm/s suggest the presence of a stenosis of more than 60% (Fig. At the aortic valve, peak velocities of up to 500 cm/sec may be possible. 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. The importance of the third parameter, the LVOT TVI, is often underestimated. The second source of error is the measurement of the aortic valve TVI obtained using continuous Doppler. These authors also proposed an absolute peak systolic velocity above 108cm/s as having good sensitivity and specificity. Thus, a woman with a score of 3,000 is very likely to present with severe AS, whereas a man with a score of 700 is very unlikely to present with severe AS. 9.9 ). The most common, as mentioned earlier, is a dominant vertebral artery, more likely seen on the left side (see Fig. 9.5 ]). The SRU consensus conference proposed the following Doppler velocity cut points: An internal to common carotid peak systolic velocity ratio <2.0, 125cm/s but <230cm/s peak systolic velocity of the ICA, An internal to common carotid PSV ratio 2.0 but <4.0, An end-diastolic ICA velocity 40cm/s but <100cm/s. While this is not a major problem in peripheral arteries when the original lumen is visible on both sides of a stenosis, lesions at the origin of the ICA typically do not have a normal lumen on both sides. In 20%-30% of patients, these parameters are discordant (usually AVA <1 cm and MPG <40 mmHg).