Field GuideSharpen up
Quick reference
Every table, classification and number worth memorizing, on one page and built to be screenshotted on rounds. Each section points back to the chapter that explains it, because a number is easier to keep when you know where it comes from.
Perfusion and chronic staging
How to grade a leg with chronic arterial disease. Explained in Foundations and Presentations.
| ABI | Interpretation |
|---|---|
| > 1.40 | Non-compressible, calcified vessels (diabetes, kidney failure); use toe pressures |
| 1.00–1.40 | Normal |
| 0.91–0.99 | Borderline |
| 0.41–0.90 | Mild to moderate PAD (the usual claudication range) |
| ≤ 0.40 | Severe PAD; rest pain and tissue loss are common |
| TBI < 0.70 | Abnormal toe-brachial index; use it when the ABI is unreliable |
A toe pressure (or TcPO2) under 30 mmHg predicts poor wound healing. When the resting ABI is normal but the story is claudication, an exercise ABI that falls by more than about 20 percent supports PAD.
| Fontaine | Rutherford | Clinical |
|---|---|---|
| I | 0 | Asymptomatic |
| IIa | 1 | Mild claudication (walks more than about 200 m) |
| IIb | 2–3 | Moderate to severe claudication (under about 200 m) |
| III | 4 | Ischemic rest pain |
| IV | 5–6 | Tissue loss: minor (5, ulcer or focal gangrene) or major (6, beyond the transmetatarsal level) |
Rutherford 4 to 6 (Fontaine III and IV) is chronic limb-threatening ischemia, staged with WIfI below.
WIfI at a glance
The SVS threatened limb classification used by the Global Vascular Guidelines to stage CLTI. Grade wound, ischemia and foot infection 0 to 3 each; the combination maps to clinical stages 1 to 4, which estimate the one-year amputation risk and the likely benefit of revascularization. Use a WIfI chart or calculator for the stage. Explained in Presentations.
| Grade | Wound |
|---|---|
| 0 | No ulcer and no gangrene (ischemic rest pain only) |
| 1 | Small, shallow ulcer on the distal leg or foot; no exposed bone unless limited to the distal phalanx; no gangrene |
| 2 | Deeper ulcer with exposed bone, joint or tendon, not involving the heel, or a shallow heel ulcer without calcaneal involvement; gangrene limited to the digits |
| 3 | Extensive deep ulcer of the forefoot or midfoot, or a deep full-thickness heel ulcer with or without calcaneal involvement; extensive gangrene of the forefoot or midfoot, or full-thickness heel necrosis |
| Grade | ABI | Ankle pressure | Toe pressure or TcPO2 |
|---|---|---|---|
| 0 | ≥ 0.80 | > 100 mmHg | ≥ 60 mmHg |
| 1 | 0.60–0.79 | 70–100 mmHg | 40–59 mmHg |
| 2 | 0.40–0.59 | 50–70 mmHg | 30–39 mmHg |
| 3 | ≤ 0.39 | < 50 mmHg | < 30 mmHg |
When the vessels are calcified and the ABI or ankle pressure is unreliable, grade ischemia by toe pressure or TcPO2.
| Grade | Foot infection |
|---|---|
| 0 | No signs of infection |
| 1 | Local infection of skin and subcutaneous tissue only; erythema 0.5 to 2 cm around the wound |
| 2 | Local infection with erythema over 2 cm, or involving deeper structures (abscess, osteomyelitis, septic arthritis, fasciitis); no systemic signs |
| 3 | Local infection with systemic inflammatory signs: two or more of temperature over 38 or under 36 °C, heart rate over 90, respiratory rate over 20 (or PaCO2 under 32 mmHg), white count over 12,000 or under 4,000 (or 10 percent bands) |
Infection is present when there are at least two of: local swelling or induration, erythema, tenderness or pain, warmth, and purulent discharge. Arterial anatomy is staged separately with GLASS, which grades the femoropopliteal and infrapopliteal disease along the target path.
Acute limb ischemia Emergency
Grade the limb first, because the category decides how fast you move. Explained in Presentations and On call.
| Category | Sensory and motor loss | Doppler (artery / vein) | Implication |
|---|---|---|---|
| I, viable | None; none | Audible / audible | Not immediately threatened; time to image |
| IIa, marginally threatened | Minimal (toes) or none; none | Often inaudible / audible | Salvageable if treated promptly |
| IIb, immediately threatened | More than toes, with rest pain; mild to moderate weakness | Usually inaudible / audible | Salvageable only with immediate revascularization |
| III, irreversible | Profound, anesthetic; paralysis, rigor | Inaudible / inaudible | Major tissue loss or permanent nerve damage; primary amputation |
| Feature | Embolic | Thrombotic |
|---|---|---|
| Onset | Sudden, dramatic | More gradual, acute on chronic |
| Source and history | Heart (atrial fibrillation, mural thrombus after MI); no prior claudication | Plaque or graft; known claudication or PAD |
| Other leg | Normal pulses | Often diminished |
| Classic site | Common femoral bifurcation | Site of prior stenosis or graft |
| Collaterals | Few (no time to form) | Often well developed |
| Usual treatment | Fogarty embolectomy | Imaging, then lysis, endovascular therapy or bypass |
Aorta and carotid
Repair thresholds, dissection and carotid revascularization. Explained in Presentations (aneurysm, dissection and carotid).
| Trigger | Threshold |
|---|---|
| Aneurysm definition (infrarenal) | ≥ 3.0 cm, or 1.5 times the expected normal diameter |
| AAA, men | ≥ 5.5 cm |
| AAA, women | ≥ 5.0 cm (SVS: consider from 5.0 to 5.4 cm) |
| Rapid growth | ≥ 1 cm in a year (some also use 0.5 cm in 6 months) |
| Symptomatic or ruptured | Any size |
| Common iliac aneurysm | ≥ 3.5 cm |
| Popliteal aneurysm | ≥ 2.0 cm, or smaller with mural thrombus |
| Splenic artery aneurysm | ≥ 3 cm, growing or symptomatic; any size in a woman of childbearing potential |
| Stanford | DeBakey | Involves | Default |
|---|---|---|---|
| A | I | Ascending, arch and descending | Emergency surgery |
| A | II | Ascending only | Emergency surgery |
| B | III | Descending only, beyond the left subclavian | Anti-impulse therapy first; TEVAR if complicated |
Complicated type B means rupture or malperfusion; most definitions add refractory pain or hypertension and rapid expansion. Anti-impulse targets (2022 ACC/AHA) are a heart rate of 60 to 80 and a systolic pressure under 120 mmHg, beta-blocker first; older teaching used a heart rate under 60. The SVS/STS reporting standards time a dissection as hyperacute (under 24 hours), acute (1 to 14 days), subacute (15 to 90 days) or chronic, and describe its extent using the aortic zones below.
| Group | Stenosis | Recommendation |
|---|---|---|
| Symptomatic | 70–99% | Clear benefit; treat within about 2 weeks of the event |
| Symptomatic | 50–69% | Moderate, individualized benefit |
| Symptomatic | < 50% | Medical therapy |
| Asymptomatic | ≥ 60–70% | Selective: low procedural risk and good life expectancy; intensive medical therapy for everyone |
Intervention assumes a perioperative stroke and death rate under about 6 percent for symptomatic and 3 percent for asymptomatic patients. Duplex grading is in Duplex criteria; CREST-2 is in Landmark trials.
Aortic zones, surveillance and endoleaks
The vocabulary of TEVAR planning, aneurysm follow-up and the post-EVAR scan. Explained in Endovascular and Open operations.
| Zone | Location | Landing here means |
|---|---|---|
| 0 | Ascending aorta, up to and including the innominate origin | All arch branches covered; needs debranching or a branched or total arch repair |
| 1 | Between the innominate and left common carotid, covering the left carotid origin | Left carotid (and usually left subclavian) revascularization |
| 2 | Between the left common carotid and left subclavian, covering the left subclavian origin | Left subclavian covered; usually revascularized electively |
| 3 | Proximal descending thoracic aorta just beyond the left subclavian | No arch branch covered |
| 4 | Descending thoracic aorta beyond zone 3 | No arch branch covered |
Left subclavian revascularization is essential when the left internal mammary feeds a coronary graft, the left vertebral is dominant, or there is a left arm dialysis access. The SVS/STS reporting standards continue the numbering down the aorta to the external iliac (zones 5 to 11).
| Diameter | Repeat imaging |
|---|---|
| 2.5–2.9 cm | Rescreen in about 10 years |
| 3.0–3.9 cm | Every 3 years |
| 4.0–4.9 cm | Every 12 months |
| 5.0–5.4 cm | Every 6 months |
ESVS intervals differ slightly; follow the local protocol. After EVAR, the SVS suggests imaging in the first month and at 12 months, then yearly duplex if there is no endoleak and the sac is stable.
| Type | Source | Action |
|---|---|---|
| I | Seal failure at an attachment site: Ia proximal, Ib distal, Ic iliac occluder | Treat promptly; the sac is pressurized |
| II | Back-filling from lumbar arteries or the IMA; the most common | Observe; treat if the sac keeps growing |
| III | Component separation or fabric defect | Treat promptly; the sac is pressurized |
| IV | Graft fabric porosity, seen at completion | Self-limited once anticoagulation wears off |
| V | Endotension: sac growth with no visible leak | Closer surveillance; reintervene if enlarging |
Duplex criteria
Velocity thresholds for the two duplex reports you will read most. Criteria vary by lab and by machine, and accredited labs validate their own, so quote the category on the report and check your lab's criteria before quoting a number.
| Stenosis | ICA peak systolic velocity | Supporting findings |
|---|---|---|
| Normal | < 125 cm/s | No visible plaque; ICA/CCA ratio < 2.0; EDV < 40 cm/s |
| < 50% | < 125 cm/s | Visible plaque; ratio < 2.0; EDV < 40 cm/s |
| 50–69% | 125–230 cm/s | Ratio 2.0–4.0; EDV 40–100 cm/s |
| ≥ 70%, short of near occlusion | > 230 cm/s | Ratio > 4.0; EDV > 100 cm/s |
| Near occlusion | High, low or undetectable | Markedly narrowed lumen on color Doppler; ratio and EDV unreliable |
| Occlusion | Undetectable | No patent lumen |
Peak systolic velocity and visible plaque are the primary criteria; the ratio and end-diastolic velocity (EDV) support them. A contralateral occlusion raises velocities on the open side, and stented arteries need their own, higher thresholds.
| Category | Duplex findings | Action |
|---|---|---|
| Normal | PSV < 180 cm/s, velocity ratio < 2.0, mid-graft velocity > 45 cm/s | Routine surveillance |
| Moderate stenosis | PSV 180–300 cm/s, ratio > 2.0 | Repeat duplex in weeks; intervene if progressing |
| High risk | PSV > 300 cm/s, ratio > 3.5, mid-graft velocity < 45 cm/s, or ABI drop > 0.15 | Angiography and repair before the graft occludes |
The velocity ratio compares the peak systolic velocity at the lesion with the segment just upstream. Vein graft surveillance commonly runs at a baseline study soon after surgery, then about 3, 6 and 12 months, then yearly; a failing graft is far easier to save than a failed one. In a native artery, a ratio of 2.0 or more generally means a stenosis of 50 percent or more.
Venous and ulcers
The venous classification and the ulcer comparison. Explained in Presentations and Foundations.
| Class | Finding |
|---|---|
| C0 | No visible or palpable venous disease |
| C1 | Telangiectasias or reticular veins |
| C2 | Varicose veins (C2r if recurrent) |
| C3 | Edema |
| C4 | Skin changes: C4a pigmentation or eczema; C4b lipodermatosclerosis or atrophie blanche; C4c corona phlebectatica |
| C5 | Healed venous ulcer |
| C6 | Active venous ulcer (C6r if recurrent) |
E, A and P add etiology (primary, secondary, congenital), anatomy (superficial, deep, perforator) and pathophysiology (reflux, obstruction). A suffix of s or a marks the limb as symptomatic or asymptomatic.
| Feature | Venous | Arterial |
|---|---|---|
| Location | Medial malleolus (gaiter area) | Toes, heel, pressure points, lateral malleolus |
| Appearance | Shallow, irregular, exudative, granulating | Punched-out, dry, pale base |
| Pain | Mild; better with elevation | Severe; worse with elevation, better dependent |
| Surrounding skin | Hemosiderin staining, lipodermatosclerosis, warm | Shiny, hairless, cool |
| Pulses | Present | Diminished or absent |
| Cornerstone | Compression, after excluding arterial disease | Revascularization |
Scores
Three scores you will be asked to calculate on the spot: DVT probability, HIT probability and cardiac risk before surgery.
| Criterion | Points |
|---|---|
| Active cancer (treated within 6 months, or palliative) | +1 |
| Paralysis, paresis or recent plaster cast of the leg | +1 |
| Bedridden 3 days or more, or major surgery within 12 weeks | +1 |
| Localized tenderness along the deep veins | +1 |
| Entire leg swollen | +1 |
| Calf 3 cm or more larger than the other side (10 cm below the tibial tuberosity) | +1 |
| Pitting edema confined to the symptomatic leg | +1 |
| Collateral superficial veins (not varicose) | +1 |
| Previously documented DVT | +1 |
| Alternative diagnosis at least as likely | −2 |
A score of 2 or more means DVT is likely: get a duplex. Under 2 means unlikely: a negative high-sensitivity D-dimer rules it out without imaging.
| T | 2 points | 1 point |
|---|---|---|
| Thrombocytopenia | Fall over 50% and nadir 20 or more (×10⁹/L) | Fall of 30–50%, or nadir 10–19 |
| Timing | Clear onset on days 5–10, or within 1 day if heparin was given in the past 30 days | Probably days 5–10 but unclear, onset after day 10, or within 1 day with heparin 30–100 days ago |
| Thrombosis | New proven thrombosis, skin necrosis at injection sites, or a systemic reaction to an IV heparin bolus | Progressive or recurrent thrombosis, red skin lesions, or suspected but unproven thrombosis |
| Other cause | None apparent | Possible |
Score 0 for a T when neither column fits (for example a fall under 30%, a fall before day 4 with no recent heparin, or a definite other cause). Total 0 to 3 is low probability, 4 to 5 intermediate and 6 to 8 high. At intermediate or high probability, stop all heparin, start a non-heparin anticoagulant and send the PF4 immunoassay.
| Factor | Counts when |
|---|---|
| High-risk surgery | Intraperitoneal, intrathoracic or suprainguinal vascular |
| Ischemic heart disease | Prior MI, positive stress test, angina, nitrate use or pathologic Q waves |
| Heart failure | History, or signs on exam or chest film |
| Cerebrovascular disease | Prior stroke or TIA |
| Diabetes | Treated with insulin |
| Kidney disease | Creatinine over 2.0 mg/dL |
Two or more points means elevated risk, which prompts an assessment of functional capacity, with further testing only if it would change management. The RCRI tends to underestimate risk in vascular surgery patients, and vascular-specific tools exist.
Anticoagulant reversal at a glance
What reverses what, for bleeding or an urgent operation. Doses are the commonly taught ranges; the hospital pharmacy protocol governs. Explained in Foundations.
| Agent | Reversal | Practical points |
|---|---|---|
| Unfractionated heparin | Protamine about 1 mg per 100 units given in the last 2 to 3 hours; maximum about 50 mg per dose | Give slowly: hypotension, bradycardia and anaphylaxis, more likely with prior protamine, NPH insulin or fish allergy. Recheck ACT or aPTT. |
| Enoxaparin | Protamine 1 mg per 1 mg enoxaparin within 8 hours of the dose; 0.5 mg per 1 mg at 8 to 12 hours | Only partial reversal of anti-Xa activity |
| Warfarin | Vitamin K 5 to 10 mg IV plus 4F-PCC (dosed by INR and weight, or a fixed dose, per protocol) | PCC works in minutes, vitamin K over hours; plasma only if PCC is unavailable |
| Apixaban, rivaroxaban | Andexanet alfa or 4F-PCC (often about 50 units/kg), per local protocol | Choice and availability vary. Time of last dose and renal function decide whether reversal is needed. |
| Dabigatran | Idarucizumab 5 g IV | Also removed by hemodialysis |
| Argatroban, bivalirudin | None; stop the infusion | Short half-lives: argatroban about 45 minutes (liver), bivalirudin about 25 minutes (kidney) |
| Alteplase (catheter-directed lysis) | Stop the infusion; cryoprecipitate and an antifibrinolytic per protocol | Check fibrinogen; stop any heparin running with it |
| Aspirin, P2Y12 inhibitors | No specific reversal | Platelet transfusion only for life-threatening bleeding or urgent surgery, per protocol; it works poorly against ticagrelor |
4F-PCC is four-factor prothrombin complex concentrate.
Conduits and access
The defaults worth stating without hesitation. Explained in Open operations (bypass and dialysis access).
| Conduit | When and why |
|---|---|
| Ipsilateral great saphenous vein | First choice for infrainguinal bypass, especially below the knee; single segment, generally at least about 3 mm; reversed, non-reversed or in situ |
| Contralateral great saphenous vein | Next, unless the other leg is likely to need its own bypass |
| Arm vein, small saphenous or spliced vein | When the saphenous vein is absent or inadequate; spliced vein still beats prosthetic below the knee |
| Prosthetic (PTFE, Dacron) | Acceptable above the knee and for aortic and iliac reconstruction; poor patency to below-knee and tibial targets |
| Access | Notes |
|---|---|
| Radiocephalic fistula (Brescia-Cimino) | Wrist; non-dominant arm and most distal site first |
| Brachiocephalic fistula | Elbow; when the forearm vessels are unsuitable |
| Brachiobasilic fistula with transposition | The deep basilic vein is brought to the surface, in one or two stages |
| Arteriovenous graft | When no vein is suitable; usable sooner (about 2 to 3 weeks, or within days for early-cannulation grafts) but lower long-term patency and more infection |
| Tunneled catheter | Last resort or bridge; highest infection and central venous stenosis risk |
Fistula first, with a nuance: an autogenous fistula has the best long-term patency and lowest infection rate, but the 2019 KDOQI guideline frames access as an individualized life plan (the right access for the right patient at the right time), so a graft can be the better choice for some. Typical mapping minimums are a vein of about 2.5 mm and an artery of about 2 mm, though thresholds vary. Save the veins: no IVs, blood draws or PICCs in the non-dominant arm of a patient with advanced kidney disease.
| Decision | Default answer |
|---|---|
| CEA closure | Patch angioplasty over primary closure, to lower restenosis |
| Amputation level for walking | Below-knee over above-knee whenever it will heal |
| Acute embolic occlusion | Fogarty balloon embolectomy |
Landmark trials in one line each
The headline result of each trial you will hear named on rounds. These are summaries for orientation; the details, subgroups and limitations matter when you apply them.
| Trial | Headline |
|---|---|
| NASCET (1991, 1998) | Symptomatic stenosis: endarterectomy sharply reduced ipsilateral stroke at 70–99% (about 26% to 9% at 2 years), gave a modest benefit at 50–69%, and none below 50%. |
| ACAS (1995) | Asymptomatic stenosis of 60% or more: endarterectomy roughly halved the projected 5-year ipsilateral stroke risk (about 11% to 5%), with very low perioperative risk. |
| ACST-1 (2004, 2010) | Asymptomatic severe stenosis: immediate endarterectomy roughly halved 5-year stroke risk compared with deferral, and the benefit lasted to 10 years in patients under 75. |
| CREST (2010) | Stenting versus endarterectomy: similar overall composite outcome; more periprocedural strokes with stenting, more MIs with endarterectomy, and older patients did better with endarterectomy. |
| CREST-2 (2025) | Asymptomatic stenosis of 70% or more, against intensive medical therapy alone: adding stenting lowered the rate of stroke or death; adding endarterectomy did not show a statistically significant benefit. Event rates were low in every arm. |
| Trial | Headline |
|---|---|
| EVAR-1 (2004 to 2016) | AAA of 5.5 cm or more, fit for open repair: EVAR had lower 30-day mortality, but the survival advantage was lost within a few years, with more reinterventions and higher late aneurysm-related mortality. |
| DREAM (2004, 2010) | AAA of 5 cm or more: EVAR had lower early mortality and complications, with similar long-term survival and more reinterventions. |
| OVER (2009 to 2019) | US veterans: EVAR had lower perioperative mortality, and long-term survival was similar to open repair. |
| Trial | Headline |
|---|---|
| BASIL (2005) | Severe limb ischemia: bypass-first and angioplasty-first had similar amputation-free survival; patients who lived beyond 2 years appeared to do better with bypass first. |
| BEST-CLI (2022) | CLTI suitable for either approach: with an adequate single-segment great saphenous vein, bypass reduced major adverse limb events or death compared with endovascular therapy; without it, outcomes were similar. |
| BASIL-2 (2023) | CLTI needing infrapopliteal revascularization: an endovascular-first strategy had better amputation-free survival than vein bypass first, driven mainly by fewer deaths. |
| COMPASS (2017) | Stable coronary or peripheral artery disease: low-dose rivaroxaban (2.5 mg twice daily) plus aspirin reduced cardiovascular death, stroke and MI, and major limb events in PAD, with more major bleeding. |
| VOYAGER PAD (2020) | After lower-extremity revascularization: rivaroxaban 2.5 mg twice daily plus aspirin reduced acute limb ischemia, major amputation, MI, ischemic stroke and cardiovascular death combined, with more bleeding. |
| Trial | Headline |
|---|---|
| EVRA (2018) | Venous leg ulcers with superficial reflux: early endovenous ablation plus compression healed ulcers faster than compression with deferred ablation. |
| ATTRACT (2017) | Acute proximal DVT: adding pharmacomechanical catheter-directed thrombolysis to anticoagulation did not prevent post-thrombotic syndrome and increased major bleeding, though it reduced its severity. |
Numbers worth memorizing
The figures that come up fast and are expected to be reflexive. Thresholds that already live in a table above (ABI, aneurysm repair, carotid, the Rule of 6s, protamine) are not repeated here.
- 65 to 75AAA screening age: one-time ultrasound in men who have ever smoked (the SVS adds women who have smoked)
- 50% / 75%Critical stenosis: about 50 percent diameter equals about 75 percent cross-sectional area
- Flow ∝ r⁴Poiseuille: halve the radius and flow falls about sixteenfold
- T ∝ P × rLaplace: wall tension climbs as an aneurysm grows
- 80–100 U/kgIntraoperative heparin before clamping, then an ACT above roughly 250 seconds
- 80 U/kg, 18 U/kg/hCommon weight-based heparin bolus and infusion for VTE, per local nomogram
- 4–6 hoursWarm ischemia skeletal muscle tolerates before irreversible injury
- < 30 mmHgCompartment perfusion gradient (diastolic minus compartment pressure) that supports fasciotomy
- > 20 mmHgSustained bladder pressure that, with new organ dysfunction, defines abdominal compartment syndrome
- Day 5–10Typical onset of HIT after heparin starts; sooner with recent exposure
- < 90 minutesSVS door-to-intervention target for a ruptured AAA
- T12 to L4Celiac T12, SMA L1, renals L1 to L2, IMA L3, bifurcation about L4
- 2 of 3Chronic mesenteric ischemia usually needs significant disease in at least two of the celiac, SMA and IMA
- 1 Fr = 0.33 mmSo 3 French is about 1 mm. Catheters are sized by outer diameter, sheaths by inner
- 0.035 / 0.018 / 0.014Wire platforms in inches: workhorse, small vessel, tibial