Free educational reference
This site is a free educational reference for vascular surgery trainees. Its calculators provide educational estimations only and do not replace clinical judgment.
myvascularrotation · field guide
The vascular rotation, within reach.
Twenty-five high-yield tools for bedside classification, hemodynamic interpretation, perioperative risk assessment, intervention planning, infection triage, and surveillance.
Perioperative cardiac risk
Calculate the Revised Cardiac Risk Index (RCRI), then place it in the context of surgical urgency, active cardiac instability, and functional capacity.
01
Emergency surgery should not be delayed for routine testing that will not change immediate management.
02
Examples include acute coronary syndrome, decompensated heart failure, unstable arrhythmia, or severe symptomatic valvular disease.
03
Intraperitoneal, intrathoracic, or suprainguinal vascular surgery. Infrainguinal and endovascular procedures are not automatically counted by this original definition.
04
05
06
07
08
Equivalent to greater than 176.8 µmol/L.
09
Functional capacity is not part of the RCRI score, but it changes the next step in a perioperative evaluation.
Pseudoaneurysm repair triage
Select the location and high-risk findings. The result separates emergency repair, prompt treatment, and the narrow group of access-site lesions that may be observed.
01
02
cm
The 2 cm observation threshold applies only to uncomplicated post-catheterization femoral pseudoaneurysm.03
04
Examples: fever, cellulitis, drainage, gas, bacteremia, or perigraft inflammatory change.
05
06
For femoral access lesions, ongoing anticoagulation lowers the chance of spontaneous thrombosis and favors intervention.
Location guide
Femoral accessObserve only when stable, asymptomatic, <2 cm, and off anticoagulation; otherwise treat.
Visceral / renalTreat pseudoaneurysms promptly regardless of diameter because rupture risk is not size-dependent.
Aortic / anastomoticNeeds aortic or vascular-team repair planning; infection and rupture demand urgent source control.
Cervical / traumaticSymptoms, progression, hemorrhage, embolic events, or threatened perfusion favor open or endovascular repair.
Dialysis accessRepair for growth, infection, pain, skin thinning/erosion, bleeding, thrombosis, or access dysfunction.
Any locationActive bleeding, shock, ischemia, infection, skin loss, or neurologic compression overrides size.
Rutherford chronic ischemia
Choose the most advanced symptom or tissue-loss finding. The result gives the chronic lower-extremity ischemia category and its clinical meaning.
01
Endoleak pattern
Identify the source of sac flow, then refine the subtype when applicable.
01
02
SVS WIfI stage
Grade wound, derive ischemia from pressure data, and grade infection. The official 64-cell matrix returns stage 1–4 and estimated 1-year amputation risk.
01
02Toe pressure is used preferentially when entered; especially useful when ABI is noncompressible.
ABI
toe mmHg
03
Rutherford acute limb ischemia
Answer each bedside question. The result combines neurologic findings and Doppler signals to estimate limb viability.
01
02
03
04
05
06
07
This distinguishes irreversible-grade sensory loss from paresthesia or limited sensory change.
08
Grade III requires profound motor loss or rigor, not venous silence alone.
09
10
Aneurysms
Start with the exact location or screening pathway. Only the relevant questions appear, so every aneurysm type stays easy to find.
Find the right pathway
Choose screening or an aneurysm location.
AAA screening — USPSTF
Enter age, sex, smoking exposure, and family history to generate the USPSTF one-time screening recommendation.
01
02
03
04
Popliteal artery aneurysm
Enter the largest diameter. Symptoms override the routine elective size threshold.
01
02
cm
03
03
Carotid intervention
Combine recent ipsilateral symptoms with NASCET stenosis. The result frames evidence-based candidacy, not procedural choice.
01
02
%
03
Traditional thresholds: <6% perioperative stroke/death for symptomatic disease; <3% for asymptomatic disease.
Chronic mesenteric ischemia
Combine the classic symptom pattern with anatomic disease. Diagnosis requires compatible symptoms and significant mesenteric occlusive disease—not imaging alone.
01
CMI should also remain in the differential for unexplained weight loss, diarrhea, nausea, or exercise-induced abdominal pain after other causes are assessed.
02
CTA is the preferred definitive study; fasting duplex is an appropriate screening test when performed in a validated vascular laboratory.
03
An acute change overrides the elective chronic pathway.
High-yield guide
Typical presentationPostprandial pain, food fear, and weight loss are classic, but the full triad is not required.
Confirm anatomyCTA defines stenosis, occlusion, collaterals, and treatment anatomy; duplex is a screening examination.
SMA is primaryThe SMA is the preferred revascularization target; endovascular treatment is generally first-line when anatomy is suitable.
Single-vessel diseaseIsolated celiac disease requires careful clinical correlation and evaluation for alternative diagnoses.
Asymptomatic diseaseDo not revascularize an incidental single-vessel stenosis routinely; manage atherosclerotic risk and follow selectively.
Acute changeContinuous pain, peritonitis, or instability requires the acute mesenteric ischemia pathway.
CEAP classification
Build the full clinical, etiologic, anatomic, and pathophysiologic descriptor.
01
02
03
04
If none are selected, the calculator reports An.
05
Aortoiliac TASC II
Select the closest lesion pattern. The result returns an anatomic grade and the original TASC treatment direction.
01
CIA = common iliac; EIA = external iliac; CFA = common femoral.
Aortic dissection
Locate the dissection and flag complications to classify Stanford/DeBakey type and management urgency.
01
02
03
IVC filter indications
Identify when temporary mechanical pulmonary-embolism protection may add benefit—and when anticoagulation remains the preferred treatment.
01
02
03
Consider thrombus burden, cardiopulmonary reserve, expected duration without anticoagulation, and whether the acute VTE can embolize.
High-yield guide
Classic indicationAcute proximal DVT or PE with an absolute or temporary contraindication to therapeutic anticoagulation.
Do not add routinelyWhen acute VTE is being treated successfully with therapeutic anticoagulation, routine filter placement is discouraged.
Anticoagulation “failure”Confirm recurrence, adherence, dose, interactions, and the underlying cause rather than automatically adding a filter.
Primary prophylaxisRoutine filters are not recommended for trauma, major surgery, or immobility without documented acute VTE.
Plan retrieval at placementUse structured follow-up; remove a retrievable filter once PE risk is mitigated unless removal risk outweighs benefit.
Resume anticoagulationStart or restart therapeutic anticoagulation as soon as bleeding risk and the clinical situation safely allow.
Acute mesenteric ischemia
Rapidly triage suspected AMI by mechanism, physiology, and peritoneal findings. A normal lactate does not exclude early ischemia.
01
CTA should be obtained without delay when AMI is suspected; do not wait for lactate elevation.
02
Peritoneal signs imply bowel necrosis until proven otherwise and require immediate operative evaluation.
03
04
Anticoagulation is commonly started early, but active bleeding and operative context require individualized judgment.
Do not miss
DiagnosisObtain biphasic CTA without delay. Oral contrast is not indicated and can obscure evaluation.
ResuscitationCorrect volume and electrolyte deficits, begin broad-spectrum antibiotics, decompress the stomach, and trend perfusion.
Arterial AMIRestore SMA flow urgently; an endovascular-first approach is reasonable when expertise is available and no laparotomy indication exists.
Venous AMITherapeutic unfractionated heparin is first-line when there is no peritonitis or bowel necrosis.
NOMIReverse the precipitating low-flow state, minimize vasoconstrictors when feasible, and consider catheter-directed vasodilator therapy.
PeritonitisProceed to emergency exploration, resect nonviable bowel, restore flow when indicated, and plan second-look assessment when viability is uncertain.
Mesenteric duplex
Interpret a fasting native-vessel PSV using either traditional or AbuRahma validation thresholds.
01
02
cm/s
03
Renal artery stenosis
Combine renal duplex criteria with the clinical syndrome to separate medical management from selective revascularization evaluation.
01
Revascularization benefit is selective; anatomy alone is not an indication.
02Enter aortic PSV to calculate the renal-aortic ratio; complete waveform and anatomic review still matters.
cm/s
cm/s
03
04
Intervention guide
Medical therapy firstMost stable atherosclerotic renal artery stenosis is treated with blood-pressure, lipid, antiplatelet, diabetes, and smoking-risk management.
Cardiac destabilizationRecurrent flash pulmonary edema or recurrent heart-failure syndromes are high-value reasons for specialist revascularization review.
Resistant hypertensionConfirm adherence, out-of-office pressure, and medication optimization before attributing uncontrolled pressure to the lesion.
Renal declineProgressive dysfunction is most concerning with bilateral high-grade disease or stenosis to a solitary functioning kidney.
Duplex contextPSV ≥180 cm/s with supportive findings or renal-aortic ratio ≥3.5 supports ≥60% stenosis; use laboratory-validated criteria.
Do not treat imaging aloneRevascularization should follow a compatible clinical syndrome, hemodynamically important disease, viable renal parenchyma, and multidisciplinary review.
Dialysis access selection & maturation
Choose fistula versus graft using the patient’s ESKD Life-Plan, then check the expected timeline and bedside warning signs for a newly created access.
01
02
03
Site choice should also preserve future options and match anticipated dialysis duration, comorbidity, and prior access history.
02The Rule of 6s is a supportive bedside heuristic, not an absolute substitute for successful two-needle cannulation.
mL/min
mm
mm
weeks
02
weeks
Standard grafts are generally not cannulated for at least 2 weeks and not until postoperative swelling has subsided. Early-cannulation graft timing is device-specific.03
04
05
Fistula versus graft
AV fistulaBest when suitable vessels and time permit: fewer infections and interventions after maturation, but slower and less predictable usability.
AV graftUseful when veins are unsuitable or access is needed sooner; cannulates earlier and has more predictable anatomy, but more infection and thrombosis.
Fistula expectationReview the wound early and evaluate maturation at 4–6 weeks. Some fistulas need several months or a salvage procedure before reliable use.
Standard graft expectationUsually wait at least 2 weeks and until swelling subsides enough to palpate the graft course.
Early-cannulation graftMay be usable sooner, but only according to the specific device instructions and local access-team protocol.
Patient firstKDOQI favors an individualized ESKD Life-Plan—not a universal “fistula first” rule—while preserving future access sites.
Vascular surveillance
Interpret bypass, EVAR, native carotid, post-endarterectomy, or post-stent findings and identify the next surveillance or referral step.
01
02
EDV cm/s
02
02
%
03
04
Includes reasonable life expectancy and acceptable procedural risk after specialist review.
05
Examples require full-study interpretation and may include progression, silent infarction, microemboli, plaque ulceration, or impaired cerebrovascular reserve.
02
PSV cm/s
EDV cm/s
03
04
05
mo since procedure
mo since duplex
06
07
Includes progressive restenosis, abnormal baseline study, contralateral disease, or patient factors such as diabetes, chronic kidney disease, smoking, or female sex.
Two-level Wells DVT score
Answer yes or no for each criterion. The score estimates pretest probability and must be followed by the validated diagnostic pathway.
01
02
03
04
05
06
07
08
09
10
Acute compartment syndrome
Combine the bedside examination with absolute and delta pressure. A clinically clear case should not wait for pressure confirmation.
01
02
03
04
mm Hg
mm Hg
Hard vs soft signs of vascular trauma
Screen an extremity injury for findings that direct immediate exploration versus vascular imaging.
Hard signs
01
02
03
04
Soft signs and screening index
05
06
07
08
Leave blank if the limb is too unstable or the measurement is not reliable.
Heparin and protamine dosing
Calculate an example intraoperative unfractionated-heparin bolus and a time-adjusted protamine range.
01
kg
02
100 units/kg IV
The cited open-AAA study protocol measures ACT after 5 minutes and then every 30 minutes; use the dose, ceiling, exclusions, and ACT target validated by the operative team.03
units
Leave blank to use the calculated bolus. Enter the actual cumulative dose when redosing occurred.04
minutes
The estimate applies the prescribing information’s approximate 30-minute IV heparin half-life.Catheter-directed thrombolysis contraindications
Screen acute limb ischemia for absolute and relative contraindications before considering catheter-directed thrombolysis.
01
02
03
04
05
06
07
08
09
10
11
Vascular graft infection
Separate a superficial surgical-site infection from prosthetic involvement, then identify anastomotic disruption, bleeding, bacteremia, and sepsis that mandate urgent source control.
01
02
03
04
05
Classification and workup
Szilagyi ICellulitis involving the wound without deeper tissue or graft involvement.
Szilagyi IISubcutaneous infection without direct contact with the prosthesis.
Szilagyi IIIInfection reaches or involves the vascular prosthesis.
Samson 3–5Progresses from graft-body involvement to anastomotic involvement, bleeding, or bacteremia.
DiagnosisObtain blood cultures and deep operative or image-guided samples; superficial swabs alone are inadequate.
ImagingCTA is first-line; FDG-PET/CT or labeled-leukocyte imaging can clarify equivocal cases.
Varicose vein treatment selection
Combine symptoms, CEAP class, reflux anatomy, peak reflux velocity, vein diameter, and prior treatment to frame the next treatment option.
01
02
03
04
cm/s
Adjunctive evidence only. Pathologic reflux is defined by reversed-flow duration and anatomy; no validated velocity cutoff selects stripping over ablation.05Diameter is documented, but current guidance advises against using truncal diameter alone to decide whether symptomatic C2 disease warrants ablation.
mm
06
About us
Where surgery meets innovation.
Joe Braham Joseph Chahine is a surgical resident with a particular interest in vascular surgery and innovation. He is the founder and manager of JRCHealthTech, LLC, a company focused on making life better for surgeons and patients.
Privacy Policy
How this free educational reference handles information.
No account or personal details
No account is needed. The site does not ask for or store names, email addresses, or contact details.
Calculator inputs stay in your browser
Inputs are entered by the visitor and processed locally in the browser. Calculator selections and patient-specific inputs are not transmitted to or stored by the site owner.
Google Analytics
This site uses Google Analytics to understand overall traffic and improve the educational reference. Google may collect usage and technical information such as pages viewed, referring source, browser or device characteristics, approximate location, and an IP address, and may use cookies or similar technologies. Calculator selections and patient-specific inputs are not intentionally included in analytics events. Visitors can limit analytics through browser privacy settings or content-blocking tools.
Questions
Visitors with questions can reach the site owner through the information in the About Us section.
References
Clinical criteria and thresholds are keyed from each section to the sources below.
- Rutherford RB, Baker JD, Ernst C, et al. Recommended standards for reports dealing with lower extremity ischemia: revised version. Journal of Vascular Surgery. 1997;26(3):517–538. Clinical classification table and citation.
- Society for Vascular Surgery. Endoleaks (Type I–V). Patient and professional reference. SVS.
- Mills JL Sr, Conte MS, Armstrong DG, et al. The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on wound, ischemia, and foot infection (WIfI). Journal of Vascular Surgery. 2014;59(1):220–234.e2. doi:10.1016/j.jvs.2013.08.003. Open review with original citation.
- Wanhainen A, Van Herzeele I, Bastos Gonçalves F, et al. ESVS 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms. European Journal of Vascular and Endovascular Surgery. 2024. Guideline update.
- Society for Vascular Surgery. Clinical practice guidelines on popliteal artery aneurysms. Guideline summary.
- Chaer RA, Abularrage CJ, Coleman DM, et al. The Society for Vascular Surgery clinical practice guidelines on the management of visceral aneurysms. Journal of Vascular Surgery. 2020;72(1S):3S–39S. Full text.
- Naylor AR, Rantner B, Ancetti S, et al. ESVS 2023 Clinical Practice Guidelines on the Management of Atherosclerotic Carotid and Vertebral Artery Disease. European Journal of Vascular and Endovascular Surgery. 2023;65(1):7–111. Guideline PDF.
- Lurie F, Passman M, Meisner M, et al. The 2020 update of the CEAP classification system and reporting standards. Journal of Vascular Surgery: Venous and Lymphatic Disorders. 2020;8(3):342–352. Full text.
- Norgren L, Hiatt WR, Dormandy JA, et al. Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II). European Journal of Vascular and Endovascular Surgery. 2007;33 Suppl 1:S1–S75. doi:10.1016/j.ejvs.2006.09.024. Citation in ACCF/AHA update.
- Isselbacher EM, Preventza O, Hamilton Black J III, et al. 2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease. Circulation. 2022;146:e334–e482. Full guideline.
- Applied Radiology. Chronic mesenteric ischemia: mesenteric artery duplex sonography and the utility of postprandial imaging. 2024. Includes traditional criteria and AbuRahma et al. validation thresholds. Peer-reviewed review.
- Olin JW, Piedmonte MR, Young JR, DeAnna S, Grubb M, Childs MB. The utility of duplex ultrasound scanning of the renal arteries for diagnosing significant renal artery stenosis. Annals of Internal Medicine. 1995;122:833–838. Criteria summarized in Ultrasound Quarterly review.
- Granata A, Fiorini F, Andrulli S, et al. Doppler ultrasound and renal artery stenosis: an overview. Diagnostic review and technical criteria. AORTA review.
- Robbin ML, Greene T, Cheung AK, et al. Arteriovenous fistula development in the first 6 weeks after creation. Radiology. 2016;279(2):620–629. KDOQI maturation criteria summarized in the Hemodialysis Fistula Maturation Study. Open full text.
- Applied Radiology. US evaluation of arteriovenous fistula complications in the emergency setting. Physical examination and dialysis-access steal findings. Peer-reviewed review.
- Zierler RE, Jordan WD, Lal BK, et al. The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures. Journal of Vascular Surgery. 2018;68(1):256–284. Guideline PDF.
- Bandyk DF. Surveillance of infrainguinal bypass grafts. Validated duplex velocity criteria. Clinical chapter.
- Chaikof EL, Dalman RL, Eskandari MK, et al. The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm. Journal of Vascular Surgery. 2018;67(1):2–77.e2. Recommendation summary.
- National Institute for Health and Care Excellence. Venous thromboembolic diseases: diagnosis, management and thrombophilia testing. NICE guideline NG158. Updated 2023. Two-level DVT Wells score and pathway. NICE recommendations.
- American Association for the Surgery of Trauma. Acute Extremity Compartment Syndrome. Clinical signs and pressure criteria. AAST clinical resource.
- US Preventive Services Task Force. Screening for Abdominal Aortic Aneurysm: US Preventive Services Task Force Recommendation Statement. JAMA. 2019;322(22):2211–2218. Recommendation summary.
- Gornik HL, Aronow HD, Goodney PP, et al. 2024 ACC/AHA/AACVPR/APMA/ABC/SCAI/SVM/SVN/SVS/SIR/VESS Guideline for the Management of Lower Extremity Peripheral Artery Disease. American Heart Association guideline hub.
- De Maeseneer MG, Kakkos SK, Aherne T, et al. ESVS 2022 Clinical Practice Guidelines on the Management of Chronic Venous Disease of the Lower Limbs. European Journal of Vascular and Endovascular Surgery. 2022;63(2):184–267. ESVS guideline.
- Huber TS, Björck M, Chandra A, et al. Chronic mesenteric ischemia: clinical practice guidelines from the Society for Vascular Surgery. Journal of Vascular Surgery. 2021;73(1S):87S–115S. SVS guideline record.
- Bhalla V, Textor SC, Beckman JA, et al. Revascularization for Renovascular Disease: A Scientific Statement From the American Heart Association. Hypertension. 2022;79:e128–e143. PubMed record.
- Giannakakis S, Galyfos G, Sachmpazidis I, et al. Thrombolysis in peripheral artery disease. Therapeutic Advances in Cardiovascular Disease. 2017;11(4):125–132. Open full text.
- Fox N, Rajani RR, Bokhari F, et al. Evaluation and management of penetrating lower extremity arterial trauma: an Eastern Association for the Surgery of Trauma practice management guideline. Journal of Trauma and Acute Care Surgery. 2012;73(5 Suppl 4):S315–S320. EAST guideline.
- DailyMed. Heparin Sodium Injection prescribing information: neutralization with protamine sulfate. US prescribing information.
- Hiippala ST, et al. Laboratory assessment of unfractionated heparin with activated clotting time and anti-Xa activity during peripheral arterial angiographic procedures. Diagnostics. 2023;13(8):1489. Open full text.
- Gloviczki P, Lawrence PF, Wasan SM, et al. The 2023 Society for Vascular Surgery, American Venous Forum, and American Vein and Lymphatic Society clinical practice guidelines for the management of varicose veins of the lower extremities. Part II. Journal of Vascular Surgery: Venous and Lymphatic Disorders. 2024;12(1):101670. Guideline PDF.
- Wiersema AM, et al. ACTION-1: study protocol for ACT-guided heparinization during open abdominal aortic aneurysm repair. Trials. 2021;22:565. Open full text.
- Singh K, et al. Peak reflux velocity as an adjunctive duplex marker in lower-limb chronic venous disease. 2020. The study reported 27.4 cm/s as an observational saphenofemoral-junction discriminator, not a treatment-selection threshold. Study record.
- Naylor AR, Rantner B, Ancetti S, et al. ESVS 2023 Clinical Practice Guidelines on the Management of Atherosclerotic Carotid and Vertebral Artery Disease. European Journal of Vascular and Endovascular Surgery. 2023;65(1):7–111. Guideline PDF.
- AbuRahma AF, Avgerinos ED, Chang RW, et al. Society for Vascular Surgery clinical practice guidelines for management of extracranial cerebrovascular disease. Journal of Vascular Surgery. 2022;75(1S):4S–22S. Full text.
- Setacci C, Chisci E, Setacci F, Iacoponi F, de Donato G. Grading carotid intrastent restenosis: a 6-year follow-up study. Stroke. 2008;39(4):1189–1196. Prospective velocity study.
- Szegedi I, et al. Role of carotid duplex in the assessment of carotid artery restenosis after endarterectomy or stenting. Frontiers in Neurology. 2023;14:1226220. Systematic review.
- Krawisz A, Carroll B, Secemsky E. Risk-stratification and management of extracranial carotid artery disease. Cardiology Clinics. 2021. Evidence review summarizing AHA/ASA recommendations for symptomatic carotid stenosis and procedure selection. Open review.
- Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation. 1999;100(10):1043–1049. doi:10.1161/01.CIR.100.10.1043. Full text.
- Thompson A, Fleischmann KE, Smilowitz NR, et al. 2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM Guideline for Perioperative Cardiovascular Management for Noncardiac Surgery. Journal of the American College of Cardiology. 2024. Full guideline.
- Attachaipanich T, Khawaja M, Takahashi EA, et al. Percutaneous coronary intervention and vascular access complications: a contemporary review. 2026. Post-catheterization pseudoaneurysm observation, thrombin injection, and operative indications. Open full text.
- Wahlgren CM, Aylwin C, Davenport RA, et al. ESVS 2025 Clinical Practice Guidelines on the Management of Vascular Trauma. European Journal of Vascular and Endovascular Surgery. 2025;69(2):179–237. Open guideline.
- Pseudoaneurysmatic complication of an arteriovenous graft in a hemodialysis patient. F1000Research. 2013;2:228. Dialysis-access pseudoaneurysm complications and operative treatment. Open full text.
- Kaufman JA, Barnes GD, Chaer RA, et al. Society of Interventional Radiology Clinical Practice Guideline for Inferior Vena Cava Filters in the Treatment of Patients with Venous Thromboembolic Disease. Journal of Vascular and Interventional Radiology. 2020;31(10):1529–1544. doi:10.1016/j.jvir.2020.06.014. Guideline summary and full-text link.
- Bala M, Catena F, Kashuk J, et al. Acute mesenteric ischemia: updated guidelines of the World Society of Emergency Surgery. World Journal of Emergency Surgery. 2022;17:54. doi:10.1186/s13017-022-00443-x. Open guideline.
- National Kidney Foundation. KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update. Patient-centered ESKD Life-Plan, AVF maturation review, and AVG cannulation timing. Guideline PDF.
- Chakfé N, Diener H, Lejay A, et al. ESVS 2020 Clinical Practice Guidelines on the Management of Vascular Graft and Endograft Infections. European Journal of Vascular and Endovascular Surgery. 2020;59(3):339–384. doi:10.1016/j.ejvs.2019.10.016. Guideline record.
Post-CEA and post-CAS velocities require reconstruction-specific criteria, morphology, interval comparison, and local vascular-laboratory validation. Near-occlusion, contralateral occlusion, low cardiac output, tandem disease, and technical factors may require different interpretation.