Fistulogram and Declots

Procedures

Access Planning Venography

• Obtain bilateral distal UE PIV access, e.g., back of hand

• Perform venography with 3 views per arm. The most central run can be tricky and requires quick injection followed by flushing, arm elevation, or use of a tourniquet

• Watch out for “pseudocompression” in patients with large body habitus. The soft tissues can create an apparent stenosis with the arm adducted that resolved with abduction.

Fistulogram and Declot

• Obtain access based on symptoms and history (e.g. may only need access towards venous outflow). Declots often require two access points to address the inflow and outflow.

  • Don’t necessarily need PIV access for fistulograms that can be challenging in these patients. Some sedate after obtaining venous access via the sheath.

  • Avoid access at buttons (locating of repeat access) since disease is often there and anastomoses.

  • Leave sufficient room for inflow access so sheath don’t overlap (“dueling sheaths”)

  • Can use ultrasound guidance or by feel since vessels are often superficial (sometimes easier without the ultrasound). Choose sheath size based on planned intervention, e.g., 7F towards outflow and 6F towards inflow.

• Heparinize - people often give 3000-7000 IU to start if planning to do more than venography. Monitoring ACT levels throughout the case can also be helpful to guide giving additional heparin.

• Declot

  • Access clotted fistula/graft towards the outflow close the arteriovenous/arterial anastomosis.

  • Gain wire access passed the clot, e.g., glidewire or Nitrex.

  • Advance curved catheter (e.g. Kumpe) with contrast injection to access where clot stops. Can also do the central venogram at this time.

  • Administer tPA and heparin into clot via pulse-spray or lyse and wait technique.

    • Dose varies, usually 3-6 mg t-PA and 1000-5000 U heparin. Some also give heparin systemically, e.g., 1000 U into the clot and 3000 U systemically.

    • Pulse-spray technique - infusion catheter such as a McNamara is placed throughout the clotted portion. 1 mL of mixture is forcefully infected every 60 sec.

    • Lyse and wait technique - inject mixture via sheath or lace throughout with Kumpe and wait 15-30 minutes (most people don’t have the patience to wait this long).

  • Advance working wire centrally, e.g., Amplatz, Benton, Coons

  • Balloon maceration of clot back to the access, e.g., 8 mm balloon is a good size for many grafts.

  • Second access towards the inflow to as much space as possible between the two access points to avoid “dueling sheaths.”

  • Gain access to inflow artery with similar wire and curved catheter combination, ideally retrograde.

  • Exchange wire for working wire.

  • (Optional) Balloon maceration from anastomosis back using a smalling balloon being careful not to over distend the artery or anastomosis.

  • Advance balloon catheter, e.g., Python, Fogarty, and pull inflated balloon back across the anastomosis three times.

  • Advance curved catheter into the inflow artery and perform fistulogram.

  • If residual clot is present, can use thrombectomy devices or devices to disrupt the clot (e.g. Cleaner). Can also inflate a balloon close to the anastomosis to occlude the inflow and flush saline through the other sheath to flush the clot out.

  • Next steps similar to fistulogram to address underlying issue.

• Fistulogram - lots of variation, common efficient approach is “outflow, inflow, polish”

  • Initial venography, often just through the access sheath in station to access the entire outflow to the heart. Inflow can be accessed via timed “recirc” run or inflating a BP cuff centrally to 10-20 mmHg above the systolic BP during the run to cause reflux.

  • Gain wire access across areas of stenosis

    • Often a glidewire and bern, Kumpe, or glidecath are sufficient. More refractory lesions many require crossing catheters or microwires and microcatheters.

    • Ultrasound is sometimes more helpful than fluoro for navigating the wire/catheter through tight stenoses particularly those adjacent aneurysmal portions of a fistula

  • (Optional) Pull back venography or pressure measurement to assess whether an area of stenosis is significant. Generally teaching is to “treat the patient not the imaging,” i.e., only treat clinically significantly lesions as plasty causes trauma and can start an unnecessary cycle of restenosis.

  • Angioplasty - often tried first to avoid stenting

    • For tight stenoses, good to serially dilate with balloon sizing to try to avoid rupture. The venous outflow can often be oversized 10-20% whereas the AV anastomosis should not be oversized, particularly if the balloon extends at all into the inflow artery to avoid arterial trauma/injury.

    • Often requires high pressure balloons such as Conquet, Gladiator/Mustang, or Dorado. Some suggest prolonged inflation (e.g. 3 minutes) but data is mixed with similar reintervention rates.

    • For refractory lesions, cutting balloons or more commonly drug-eluting balloons can be considered. Downside is reimbursement issues. Probably good for refractory lesions particularly in areas where stenting is not ideal.

  • Stenting - good for resistant areas of stenosis with substantial recoil, particularly at venous anastomosis (well-proven in FOUR RCTs and tends to be cost neutral to cost saving), pseudoaneurysms at access site, and vein rupture

    • Stent grafts are superior to bare metal stents.

    • Try to avoid if possible as it cages off anatomy for future access and it a temporary fix in a chronic condition. Also avoid stenting in areas such as between the clavicle and first rib which is likely to be crushed compromising long-term patency.

  • Inflow - if stenosis/clot, two to three passes with Fogarty balloon. If resistant, can angioplasty with 1:1 sizing

  • Check flow and anatomy with angiogram/venography and polish as needed.

  • End points

    • Palpable thrill - best predictor of long-term success

    • <30% residual stenosis (KDOQI/SIR/ACR)

    • Normalized pressure ratio (NPR) <0.33 = venous limb pressure / contralateral arm pressure

    • Pressure gradient measurements tend to be unreliable.

• Some give additional 3000-5000 IU heparin at the end

• Obtain hemostasis: e.g. Stat seal and dressing or Woggle technique: (throw stitch near access site -> cut off needle -> thread both ends through a flowstopper -> remove sheath while synching down and locking in place -> remove in post-op before discharge)