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Endovascular access

From Surgopaedia

Choice of site

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  • Consider:
    • Appropriateness for procedure - size, location
    • Ability to obtain haemostasis afterwards - seal with manual compression/closure device
      • Difficult factors: significant calcification; small diameter vessels
    • Ability to safely convert to open if there is a complication
    • Ensuring that cannulation of that site will have minimal adverse effects on the tissue being supplied by the access vessel
      • Rarely an issue for diagnostic procedures
  • Options:
    • CFA most common, followed by brachial and radial artery (when a smaller-calibre device can be used and femoral access is disadvantageous)
    • Popliteal and tibial can be used for lower extremity interventions, but rarely first choice, and not considered for diagnostic-only procedures
    • Others: carotid, subclavian, axillary, iliac

Vessels:

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  • Axillary
    • Easier to use brachial, since it's easier to access and there's minimal difference in calibre
    • Technique
      • Upper arm in abduction and flexion
      • Locate intramuscular groove between triceps and coracobrachialis
      • Haemostasis by compression against the humerus (bleeding can create a compartment syndrome for the median nerve)
  • Iliac artery
    • Open surgical approach is easiest
    • Percutaneous techniques are contraindicated due to difficulty in establishing haemostasis
  • CFA
    • Can be compressed against femoral head
    • Can be converted to an open approach easily with a groin cut-down
    • Can accommodate devices as large as 26F and suture-based closure devices
    • Anatomy:
      • Continuation of EIA as it crosses under the inguinal ligament, giving off circumflex iliac and superficial epigastric branches
      • 5-8cm long
      • Bifurcates into SFA and PFA
      • Medial to femoral nerve, lateral to CFV
      • Overlies medial aspect of femoral head
    • Antegrade access:
      • Harder than retrograde, as you need to enter CFA above the bifurcation, which means a steep downward angle
      • In obese patients, might need someone to retract the pannus
      • Entering too close to the bifurcation means it will be difficult to selectively cannulate the SFA
    • Retrograde access:
      • Aim to obtain access over the femoral head, just above the femoral bifurcation but below the inguinal ligament with the needle pointing cranially
      • Punctures cranial to the IL may be difficult to seal
      • Punctures too distally increase risk AVF from PFA or plaque dissection of the proximal SFA
  • Brachial artery
    • Can be compressed against the humerus - can be challenging though
    • 6F sheaths can be used safely in most patients
    • Anatomy
      • Palpable just over the olecranon process when the arm is supinated
      • Use USS in combination with micropuncture technique
      • Risk of median nerve compression with a haematoma
    • Technique
      • Need to delineate the bifurcation prior to attempting access, so that entry into the largest part of the vessel is achieved
  • Popliteal artery
    • USS very useful in differentiating from popliteal veins
    • Haemostasis can be difficult, as effective compression in the fatty popliteal space is hard
    • Anatomy:
      • Continuation of the SFA as it exits Hunter's canal in the distal medial thigh
      • Divides into ATA and TPT
      • Flanked on each side by dupicated popliteal vein
      • Can be accessed medially either above or below the knee, or posteriorly using a prone position
  • Tibial arteries/peroneal arteries
    • Commonly accessed using micropuncture technique assisted by USS
    • Small sheaths and soft wires
    • Anterior tibial artery
      • Anatomy
        • Anterior compartment of leg, dorsal surface of the foot (dorsalis pedis)
    • Posterior tibial artery
      • Anatomy
        • Palpable near the ankle, and amenable to access here as it is easily compressed
    • Peroneal artery
      • Anatomy
        • Deep posterior compartment of the leg
        • Generally travels between tibia and fibula
        • Hard to reach, rarely used
  • Radial artery
    • Can accommodate sheaths between 4F and 6F

Adjuncts to obtain access

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  • Manual palpation of pulse
    • Two fingers - one proximal and one distal, spread out by a few centimetres
    • Access needle inserted directly between the two fingers
  • Radiographic guidance
    • Useful when a pulse is either absent, or not able to be appreciated due to overlying scarring
  • USS guidance

Technique

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  • Needles
    • Single-wall: almost universally used for percutaneous access. 18-gauge needle for 0.035-inch guide wire. 21 gauge needle for 0.018-inch guide wire.
    • Double-wall: blunt-tipped hollow needle with an inner bevelled stylet. Historically used to puncture both anterior and posterior walls, then inner stylet removed, then needle slowly withdrawn until blood comes back.
  • Micropuncture needle technique
    • Vessel identified with USS
    • 21-gauge needle inserted at 30-45 degrees, so it enters the vessel at site of visualisation
    • 0.018-inch floppy tip guidewire inserted into the vessel
    • Needle removed from over the wire
    • 4F introducer sheath
    • Inner canula of sheath removed, along the guidewire
    • 0.035-inch wire can be inserted at this point and sheath upsized to 5F or 6F if needed for definitive access
  • Standard needle technique (for easily palpable femoral pulses in otherwise uncomplicated anatomy)
    • 18-gauge needle and 0.035-inch J-tip moveable core steel guidewire (don't use hydrophilic-coated guidewire for initial entry as the coating can shear off and embolise from the needle)
    • Straight to 5F or 6F sheath
    • This technique is helpful in situations where tracking the 4F sheath over the less supportive 0.018-inch wire can be hard, like in scarred groins or when accessing a Dacron graft
  • Sheaths
    • Inside calibre measured by French size, from 4F to 11F
    • Have a haemostatic valve at the end
    • Braided sheaths can be used when cannulating a vessel through dense tissue or making sharp turns that can lead to kinking of the sheath
    • Most commonly 10cm length for diagnostic purposes, but available 5-100cm
    • 45cm sheath typically used working on the contralateral iliac system or beyond, and a 90cm sheath used to work on the carotids. Chosen sheath should be no longer than necessary.
  • Guidewires
    • Jagwire (Boston Scientific) commonly used at Austin
      • Nitinol with Endo-Glide coating
      • 5cm hydrophilic tip
      • 0.025 or 0.035-inch diameters
      • 260 or 450cm length
      • Straight or angled tip
      • Good for use in biliary duct cannulation from top or bottom
  • Catheters
    • Vehicles used to deliver the radiographic contrast agent to the area of interest
    • Most catheters 2F-6F
    • 2F and 3F are microcatheters for delivery of embolisation coils
    • Types of diagnostic catheters:
      • Non-selective - used to inject a high volume of contrast into relatively large blood vessels, typically using power injection. Multiple side holes along the last 15mm to reduce the 'jet effect'.
      • Selective - their shape facilitates engagement in the orifice of a branch vessel, for either direct injection or subsequent guidewire passage. Generally have an end hole only (no side-holes), and therefore can't inject with too much pressure. Divided into single-curved, double-curved and reverse-curved configurations.
        • Single-curved: ideal for cannulating a side branch vessel coming off at less than 45-degree angle from the aorta.
        • Double-curved: angle up to 90 degrees or greater.
        • Reverse-curved: typically have a 180-degree curve, for vessels that come off steeply.
    • Interventional catheters:
      • Crossing
        • Used for crossing occluded/stenotic vessels
      • Guiding catheters - essentially sheaths with tips with different lengths and shapes to permit selective cannulation
  • Closure devices
    • Simple manual compression
      • Not too tight - lead to thrombosis
      • Hold for 5-20 minutes
      • 6 hours mandated bedrest
    • Closure devices
      • Seal the access hole in some way or another
      • Minimise need for compression and bed rest
      • Increase risk of groin infection and leg ischaemia.
      • Angio-Seal - intra-arterial absorbable anchor is placed against an externally placed collagen sponge, and these are sandwiched together. Good for arteries >5mm without significant calcification, and can be used to close sites up 8F. Can get ischaemic complications when deployed incorrectly.
      • Mynx - polyethylene glycol polymer closes the tissue track over the puncture site, which dissolves within 30 days. Haemostasis for up to 6F. Higher risk of ischaemic and bleeding complications.
      • ProGlide - single polypropylene stitch to suture close arteriotomy sites up to 6F. Can be used off-label to close large arteries by putting two of them together. Device failure - manual compression, additional ProGlide use, or open repair.


Consent: bleeding, infection, thromboemboli, failure, additional procedures, contrast allergy or nephropathy, limb loss, anaesthetic, neurovascular


Complications

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  • Access site
    • Risk factors
      • Obesity
      • Diseased access vessels
      • Large sheath size
      • Anticoagulation
    • Bleeding (1%)
      • Initial management:
        • Apply pressure while the patient is stabilised (push against an anatomic structure)
        • Reverse anticoagulation
        • Reassess with imaging (?CTA or USS)
        • Endovascular balloon control as an adjunctive technique while definitive management is obtained
      • Definitive management:
        • Continued bleeding may need open repair
        • Endovascular treatment with peripheral endografting
    • Haematoma (3%)
      • Initial management:
        • Apply pressure while the patient is stabilised (push against an anatomic structure)
        • Reverse anticoagulation
        • Check Hb every 6 hours
        • DUS to exclude pseudoaneurysm
      • Open surgical repair
        • Indications: haemodynamic instability, persistent anaemia despite transfusions, pseudoaneurysm unsuitable for thrombin injection; skin compromised, nerve compression, severe pain
      • Retroperitoneal haematoma:
        • Suspect in hypotension, diaphoresis, groin pain, abdominal pain, bradycardia, back pain
        • CT is best test
        • Indications for intervention - neurologic deficits in the extremity, haemodynamic instability, ongoing blood loss, severe pain
        • Open procedure:
          • Either groin incision or an incision above inguinal ligament
          • Expose arteriotomy and repair
        • Endovascular option would be a covered stent, good in high injuries
    • Thrombosis (2%)
      • Risk factors - significant local atherosclerotic disease, previous groin reconstruction
      • Usually becomes apparent after manual compression is complete
      • Endovascular - mechanical thrombectomy, thrombolysis, atherectomy
      • Surgical - groin exploration with femoral endarterectomy, patch angioplasty, thromboembolectomy
    • AVF (0.9%)
      • Tend to occur with more distal punctures, especially of PFA itself
      • Detected by palpable thrill or continuous bruit
      • Check for distal ischaemia and cardiac dysfunction
      • DUS best test to diagnose
      • Many are asymptomatic and will close spontaneously (38% within 12 months). Need follow-up DUS.
      • Persistent, symptomatic or enlarging AVF should undergo repair
        • Surgical: open cut-down
        • Endovascular - balloon-expandable stent grafts
    • Pseudoaneurysm (0.6%)
      • Pulsatile groin mass, systolic bruit
      • Perform DUS if suspicious
      • If there is significant extension into the retroperitoneum, CT might help to fully define its extent
      • Complications: nerve compression, distal embolisation, skin necrosis
      • Observation alone is reasonable in small PSAs
      • USS-guided compression works 74%-93%. Less effective on anticoagulation, large pseudoaneurysms, patient discomfort.
      • Thrombin injection for pseudoaneurysm
        • Allows fibrin clot to form and thrombose the PSA
        • Indications: persistent, enlarging, symptomatic
        • Needs to be a long pseudo aneurysm with a narrow neck (<0.55cm) to reduce the risk of injecting thrombin into the artery (very difficult to get out if that happens)
        • Anticoagulation use associated with incomplete thrombosis
      • Surgery:
        • Larger PSAs
        • Wide neck
        • Failed alternative treatment
        • Endovascular is a possibility
  • Catheter/guidewire related
    • Perforation
      • Confirm with extravasation of contrast
      • Usually seals with conservative management
      • Management depends on vessel and clinical status
      • Can use covered stents
      • Angioplasty-induced perforation of infra-inguinal vessels isn't life-threatening but can result in pseudoaneurysm or occlusion
    • Dissection (7% after PTA)
      • Balloon inflation causes stretching and disruption of the plaque and overlying intima that results in a tear or dissection. This can be propagated distally and result in flow-limiting obstruction or arterial occlusion.
      • Seen on arteriography - luminal flap with contrast on both sides
      • Usually treated by sustained inflation of low-pressure angioplasty balloon in an attempt to 'tack down' the dissection flap
      • If unsuccessful (>30% or flow-limiting dissection), stent can be used
    • Embolisation (1-3%)
      • Any wire, catheter or sheath manipulation (especially atherectomy though) can result in embolisation, in patients with large-volume atheromatous disease
      • Can result in trashing of runoff vessels, or stroke if in aortic arch
      • Prevention better than cure - institute anticoagulation prior and minimise manipulation across the lesion, and can use embolic prevention devices in setting of large-volume plaque burden, significant thrombus burden or single-vessel runoff
      • Management:
        • Endovascular rescue - heparinise, trial with aspiration catheter, or trial with AngioJet if you think it's thrombus, thrombolytics
        • If unsuccessful and there are signs of acute ischaemia, treat with standard open procedures
  • Systemic
    • HIT
    • Contrast nephropathy
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