Neurosurgery notes/Procedures/Cranial procedures/Vascular procedures/Vascular bypass

Vascular bypass

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Parent item
Vascular procedures
Sub-item
Direct revascularization procedures
Indirect revascularization procedures

Bypass

Indication
  • Moyamoya
  • Large Aneurysm
  • Skull base tumour
Trials for bypass
Conclusion
  • EC-IC bypass remains an option in carefully selected patients with ischemic cerebrovascular disease, limited to interdisciplinary and specialized high-volume centers and within the framework of controlled studies.
  • MoyaMoya -useful
  • Carotid occlusive/stenotic atherosclerotic disease not beneficial.
    • Studies still looking for a subgroup that might be helpful
Moyamoya
  • Japan Adult Moyamoya (JAM) Trial
    • Significant difference between surgical and nonsurgical group, suggesting the preventive effect of direct bypass against rebleeding.
    • The difference is pretty minimal and is only significant in the kaplan meier analysis (log-rank test)
    • Class I level A evidence for bypass
      • Significant morbidity
        • Medical rx
          • 34.2%
        • B/L STMC
          • 14.3%
      • Rebleeding
        • Medical rx
          • 31.6%
        • EC-IC bypass
          • 11.9%
    • Details of outcomes and cox regression analysis
        • ㅤ
        Surgical group (n=42)
        Surgical group (n=42)
        Nonsurgical group (n=38)
        Nonsurgical group (n=38)
        Hazard ratio (95% CI)
        P value
        ㅤ
        n
        Rate, %
        n
        Rate, %
        ㅤ
        ㅤ
        Primary end point
        6
        14.3
        13
        34.2
        0.391 (0.148–1.029)
        0.057
        - Recurrent bleeding
        5
        11.9
        12
        31.6
        0.355 (0.125–1.009)
        0.052
        - Completed stroke
        1
        2.4
        0
        0.0
        ...
        ...
        - Crescendo TIA (bypass required)
        0
        0.0
        1
        2.6
        ...
        ...
        Secondary end point (recurrent bleeding or related death/severe disability)
        5
        11.9
        12
        31.6
        0.355 (0.125–1.009)
        0.052
  • Teo 2022 largest single centre series mixture of direct and indirect bypass for both adult and paeds
    • 4.2% per-bypass-procedure (6.8% per patient) 30-day major stroke risk and a 0.6% per-patient-year long-term stroke risk.
    • Adult and paediatric patients had direct revascularization,
      • 4.2% per-bypass-procedure (6.8% per patient) 30-day major stroke risk
      • 0.6% per-patient-year long-term stroke risk.
  • Prospective single center cohort study
    • 113 consecutive patients
      • Combined direct and indirect bypass
      • Stroke and death
        • Periop 0%
        • At 1 year 0%
        • At 2 years 1.9%
    • Annual rebleeding
      • Natural history
        • 6-7%/yr
      • EC-IC bypass
        • 1.9%/yr
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Intracranial ICA trial
  • Japanese EC-IC Bypass Trial (JET):
    • Surgical patients experienced a significant reduction in major stroke or death in the 2-year period after surgery) as compared with the medical patients at 15 months (5.1% vs 14.3%)
  • Carotid Occlusion Surgery Study (COSS)
    • Excellent bypass graft patency and improved cerebral hemodynamics
      • 98% at the 30 day post-operative
    • STA-MCA anastomosis did not provide an overall benefit on ipsilateral two-year stroke recurrence, mainly due to a much better than expected stroke recurrence rate (22.7%) in the medical group in the trial (Surgery had a rate of 21.0%), but also because of a significant peri-operative stroke rate (15%)

Types of graft

      Type
      Comments
      Demand
      Initial flow
      Patency
      Superficial temporal artery
      Pedicle vessel
      Low flow
      15–25 ml/min (may increase with time)
      >95% (e.g. EC-IC bypass trial, COSS)
      Radial artery interposition graft
      Same size as M2 branch. Risk of vasospasm.
      Moderate-High flow
      40–80 ml/min
      >90% at 5 years
      Saphenous vein graft
      Greater length but has valves
      High flow
      70–140 ml/min
      82% patency at 5 years
    • Low resistance circulation, vein graft not a disadvantage
    • Other low flow graft <50ml/min
      • OA
      • MMA
  • The type of graft used depends on preoperative determination of amount of flow augmentation necessary, the size of the recipient graft and the availability of donor vessel:
    • Pedicle arterial grafts: STA, occipital artery
      • Low-flow (15 – 25ml/min)
      • Only one anastomosis required
      • 95% graft patency in superficial temporal artery-middle cerebral artery (STA-MCA) bypasses
    • Radial artery graft
      • Moderate to high flow (40 – 70 ml/min)
      • Advantages:
        • Physiological conduit for arterial blood;
        • Constant location makes it easy to harvest;
        • Lumen size closely approximates that of M2 or P1 and reduces flow mismatch with subsequent flow turbulence and graft thrombosis
      • Disadvantages:
        • Risk of vasospasm (reduced with pressure distension technique)
        • >90% graft patency at 5 years
    • Saphenous vein graft
      • High flow (70 – 140 ml/min)
      • Advantages:
        • Easy accessibility
        • Longer length
      • Disadvantages:
        • Risk of thrombosis at distal anastomosis due to flow mismatch and turbulence;
        • Lower graft patency rates
          • 82% graft patency at 5 years