Fem-pop occlusive disease

Aetiology

Asymptomatic
Intermittent claudication
Critical limb ischaemia
- Ischaemic rest pain (forefoot pain at rest)
- Ulceration on distal toes/bony prominences
  - Look for arterial-type ulcers
- Gangrene
ABI (ankle systolic pressure in each leg divided by the highest brachial artery systolic pressure
- Normal 0.9-1.1
- <0.9 with a compatible history is diagnostic of arterial occlusive disease (sensitivity of 95% in identifying angiographically confirmed PAD)
- Claudication ABI is typically 0.4 - 0.9
- Rest pain or tissue loss ABI is typically <0.4
- ABI > 1.1 probably reflects calcified arteries (diabetes, ESRF)
  - Need to use arterial waveforms, toe waveforms/Doppler pressures, and transcutaneous oxygen sats in this case
- Claudicants with single-level stenosis may only show a reduced ABI after exercise
  - >20% reduction post-exercise is abnormal

Type A and B: endovascular first

Type C: case by case

Type D: surgery first-line

Ongoing BEST-CLI trial attempting to give a better optimal treatment strategy

Factors required for bypass
- Adequate inflow site
  - Choice based on examination/USS, but needs to be confirmed with angio
  - Address haemodynamically-significant lesions prior to bypass
  - Most common choice in fem-pop bypass is CFA
    - If significantly diseased, consider CFA endarterectomy
  - PFA or SFA are alternative inflow sources
- Adequate outflow site
  - Ideally: normal in calibre, free of stenosis, in continuity with at least one of the arteries supplying the foot
  - Below-knee popliteal is best. If that's occluded, best bet is tibial artery with best foot runoff
  - Can consider ulcer locations sometimes (angiosome theory)
- Adequate conduit (best is great saphenous vein - no sclerosis, at least 3mm in diameter)
  - Vein mapping - diameter, compressibility, wall thickness, flow
  - GSV preferred, otherwise use cephalic/basilic/small saphenous
  - GSV should be reversed, but can also be done in situ
  - Prosthetic is last resort - PTFE. Improved patency rates by using an adjunctive vein cuff (Miller or St Mary's) or Taylor patch
If these are not present, endarterectomy/profundoplasty might be a better alternative
Surgery remains best option for patients with ischaemic rest pain or tissue loss.

PFA supplies blood to thigh, SFA to leg via adductor canal
SFA enters popliteal fossa at apex, where it becomes POPA
CFV just medial to CFA in fem triangle, with GSV entering the CSV at fossa ovalis, and lymphatics medial to that.
- Note PFA generally posterolateral branch of CFA
Below-knee POPA is variable in length before dividing into ATA (which travels laterally, enters anterior compartment, becomes DP) and TPT (branches into peroneal and PT, and enters deep posterior compartment)

GSV HARVEST

Identify GSV in fem triangle. Incise directly over vein to avoid undermining.
Dissect periadventitial tissue away sharply. Ligate tributaries with silk (leave a short stump, don't narrow the conduit)
Continue dissection distally until adequate length is obtained
Place small clamp flush with GSV. Divide. Oversew stump with running monofilament.
Preparation
- Place in a bath of heparinised saline and papaverine
- Clamp proximal end with small bulldog
- Flush heparinised saline from distal end
- Meticulously repair small tears
Store in chilled, heparinised blood until ready to use

SSV HARVEST

SPLICING VEINS

FEM TO ABOVE KNEE POP BG

Incision directly over CFA pulse and dissect down to femoral sheath, use self-retainers
- Expose CFA proximally to inguinal ligament
- Continue dissection distally to proximal SFA
- Identify and expose PFA
AKP exposed from medial thigh - longitudinal incision anterior to sartorius and retract sartorius posterolaterally
Divide deep fascia to expose popliteal fossa. Dissect and mobilise artery.
Identify a healthy section of artery and place proximal and distal clamps
Tunnel conduit - put clamps from groin to popliteal fossa in anatomical plane, and pull vein through
Proximal anastamosis first, then distal

TO BELOW-KNEE POP

INTRA-OP BYPASS GRAFT ASSESSMENT

Confirm graft patency
Establish integrity of conduit
Confirm adequacy of outflow
Identify potential conduit, anastomotic, technical defects that may predispose to thrombosis
Doppler foot

WOUND CLOSURE

Early graft thrombosis (5%)
- Often results from technical error/poor conduit/poor outflow
- Needs return to theatre
Late graft thrombosis (>30 days)
- Intimal hyperplasia
Bleeding (0.4%)
- Bleeding of vein graft can be repaired with direct cut-down onto vein
Infection
- Deep infections require aggressive debridement
Lymphatic leak
Compartment syndrome