- Diagnostic angiographic catheter properties include size, shape, radiopacity, torque capacity and softness of tip. Larger-lumen/guiding catheters aid placement.
- Bentson catheter – angled tip with distal wire curved in opposite direction, Bentson 3 greater curve than 1. For proximal arch branches.
- Berenstein catehter – stright with angled tip. For distal arch branches.
- Cobra catheter – angled tip with distal wire curved in same direction, Cobra 3 curve more proximal than 1. For anterior abdominal aorta branches.
- DVS A1 and A2 – straight with angled tip. For distal arch branches.
- Headhunter catheters – hooked with anled tip away. For backwards facing branches.
- Hockey stick catheter – hooked with gentle curve away
- Hook catheter – straight with hooked end
- Mani catheter – hook with acute proximal angulation away.
- Pigtail flush catheters
- Renal double curve – hooked with proximal curve in same direction
- Reuter catheter – hooked with tip angulated away
- Shepherds flush catheter – hooked with tip angulated away, gentle proximal curve in same direction
- Shepherds hook catheter – shallow hook with tip angled away so is almost perpendicular to main catheter.
- Sidewinder catheter – pulled back into a backwards facing vessel, only so fast as length of its tip. To make shape pull back wire then push and twist.
- Simmons catheter – S-shaped, hooked with long distal portion and tip angulated away
- Straight flush catheter – straight
- Ultra bolus flush catheter – pigtail-like
- Vertebral catheter – tip angled
- Grollman catheter – multi-sidehole pigtail.
- Hinck catheter – angled 45deg
- Microcatheters are </= 3 French, for neurointerventional, small vessel embolisation/infusion. Distal platinum marker, otherwise relatively radiolucent.
- Drainage catheter properties include size, biocompatibility, radiopacity and shape/retention/softness. Retention for pigtail usually retention suture; straight includes mushroom tip or inflatable balloon.
- Balloon catheters. Soft/pliable occlusion or Fogarty balloons to clear thromboses. Rigid for dilatations/angioplasty utilising guide wires 0.018/0.014 inch (coronary/peripheral/neuro angioplasty) or 0.035 inch (better support, larger balloons; most peripheral intervention). Do not re-wrap well, hence larger access site/introducer sheath required. Noncompliant balloons are firm when reaching stated size for dificult, hard lesions. Compliant catheters increase pressure with dilatation for fine-tuning angioplasty.
- Central venous catheters. Devices for direct puncture without implantation for temporary care/monitoring eg central venous lines, Swan-Ganz. Implanted devices are subcutaneous tunned or have implanted ports in subcutaneous pocket. Tunneled have retaining fabric cuff (Dacron polyester) fusing w connective tissue; less expensive/invasive, but higher infection, less cosmetically desirable; incl cuffed central venous (eg Hickman) and haemodialysis lines (eg PermCath).
Guide wires sizes 0.010 to 0.038 inch.
- Spring guide wires stainless steel wound in spring.
- Bentson wire – floppy atraumatic distal 60mm.
- Nitinol wires from nickeltitanium allow and organic hydrophilic coating which absorbs water and becomes slippery.
- Terumo glidewire
- Self-expanding stainless steel or nitinol. Flexible and can be large, but more difficult to place precisely due to foreshortening.
- Balloon-expandable mostly stainless stell. Less flexible, but more precisely placed.
- Coated stents provide drug delivery.
- Stent grafts covered by fabric (polytetrafluoroethylene). Smallest 7-12 French. Aortic stents large up to 30French, require surgical arterial access.
Embolic agents properties include location of occlusion (proximal/distal), permanence and radiopacity.
- Macrocoils (0.035-0.038in stainless steel/platinum) – proximal, permanent.
- Microcoils (0.010-0.018in, platinum) – proximal, permanent.
- Polyvinyl alcohol sponge (denatured ethanol particles mixed with contrast) – distal (arteriolar level), temporary.
- Detachable balloons (silicone) – inflated with contrast to size, permanent.
- Glue (polymerisation of cyanoacrylate mised with ethiodol and tantalum powder) – distal (depending on rate of polymerisation), permanent.
- Alcohol (sclerosing agent mixed with contrast powder) – distal (capillary level), permanent.
- Gelatin sponge (derivative of pork skin) – proximal, radiolucent, temporary.
- Microspheres (acrylic polymer mixed with contrast) – distal (arteriolar level), unknown permanence.
- Fentanyl – synthetic opioid. 25-100mcg initial, 25-75mcg boluses. Rapid onset, short duration.
- Naloxone – narcotic antagonist. 0.1-0.4mg IV boluses titrated slowly. Sudden arousal and pain if too much given. t1/2 short ~20min.
- Midazolam (Hypnovel) – benzodiazepine (anxiolytic, sedative, muscle relaxant, anti-convulsant). Unpredictable dosing, initial 0.5-2mcg then 0.5-1mg boluses, max total 5mg. Smaller dose with elderly, COPD, CRF, CHF. Onset rapid ~2min, t1/2 short 1.5-2.5hrs (may be up to >10hrs). Contraindications myasthenia gravis, allergy. Potentiation of resp depression w narcotics, antipsychotics, hypnotics, anxiolytics, antidepressants, antiepileptics, sedative antihistamines. Prolonged effect (altered hepatic metabolism) w Cimetidine, erythromycin, diltiazem, verapamil, ketoconazole, intraconazole (prolonged observation before discharge). ‘Unforeseeable’ reactions w alocohol, avoid within 12hrs. Observe at least 2hrs post. No driving/operating machinery for 12hrs.
- Flumazenil (Anexate) – benzodiasepine antagonist. 100mg/mL in 5 or 10mL ampules. Initially 200mg over 15sec, 100mg as needed avery minute. t1/2 <1hr.
- Antibiotics contraversial, used for contaminated (inflammation without pus) or dirty (purulent or infected GI/GU site) procedures.
- Vasodilators (Rx vasospasm from iatrogenic/catheter-induced, trauma, meds etc) nitriglycerin (100mcg intra-arterial) and papaverine (25-100mg intra-arterial).
- Vasoconstrictor (piteressin/Vasopressin)
- Anticoagulants (inhibit thrombin generation) heparin IV, warfarin po, direct thrombin inhibitors (bivalirudin, hirudin, argatroban).
- Antiplatelet (reduce thrombus formation) aspirin po, thienopyridines (ticlipidine 250mg po, clopidogrel 75mg po), glycoprotein IIb/IIIa antagonists (abciximab IV).
- Thrombolytic (lyse/dissolve existing thrombi) directly into thrombus (faster and less dose than IV) streptokinase, tissue plasminogen activator (urokinase, alteplase, reteplase).
Sutures, Needles and Knots
Suture properties include strength, uniformity, hand (feel/smoothness, how a knot sets/snugs down, firmness/body), and extensibility (stretching slightly w knot tying then recovering, indicating knot snugness).
Length of suture support required for healing is few days for muscle, subcutaneous; several days for skin; weeks-months for fascia and tendon; long-term stability for vascular prosthesis. This alters with patient factors (infection, debility, resp problems, obesity, diabetes etc).
- Absorbable sutures are biological origin (eg surgical gut, digested by tissue enzymes) or synthetic polymers (broken with hydrolysis in tissue fluids). Some types provide provide extended support up to 6/12. Include surgical gut (absorption dependent on pt factors), coated Vicryl (polyglactin; braided or monofilament, 50% strength at 3/52), coated Vicryl Rapide (braided, 50% @5/7), Monocryl (poliglecaprone; monofilament, 50% @1/52), PDS II (polydioxanone; monofilament, 50% @ 4/52), Panacryl (braided synthetic, 60% @6/12).
- Nonabsorbable sutures become encapsulated or walled off by fibroblasts. Include Perma-hand (silk; braided), surgical stainless steel (mono or multifilament), Ethilon (nylon; monofilament), Nurolon (nylon; braided), Mersilene (polyester; braided or monofilament), Ethibond Excel (polyester; braided), Prolene (polypropylene; monofilament), Pronova Poly (hexafluoropropylene; monofilament)
Construction of sutures include:
- Multifilaments are several strands braided or twisted together. Generally easier to handle and tie, increased friction with good tying qualities.
- Monofilament made from single strand. Reisits harboring micro-organisms and ties down smoothly. Coefficient of friction low (loosening knots) and position memory (returning to shape set by extrusion process or packaging), may break with repeated bending (eg instrument tie).
Absorbable monofilament used in contaminated regions to prevent conversion to infection. Best cosmetiis results from close prolonged apposition of wound with avoidance of irritants – smallest inert monofilament (nylon, polypropylene), SC closure (cf skin), topical skin adhesive or skin closure tape.
Suture size is smallest with increased number of 0’s (eg 5-0 = 00000).
Most surgical needles are stainless steel. Ductility is ability to bend before breaking (indicating excessive force). Strength is ease of bending. Swaged sutures join the needle and suture together as a continuous unit. Body/shaft of the needle may be straight, half-curved, curved or compound curved. Cross section may be round, oval, side-flattened rectangular, triangular or trapezoidal; different shapes provides greater stability in the needle holder. Needle points are cutting, tapered or blunt.
Ideal knot is firm (slippage impossible), small (reduce tissue irritation), not excessively tense (suture breakage, tissue damage). During tying friction/sawing between strands should be minimised (can weaken structure), avoid crushing/crimping during handling (hold free ends), maintain traction after 1st loop to prevent loosening of the throw, final tension of final throw should be as horizontal as possible. Extra ties do not add strength of a knot, only to increased bulk.
- Two-handed square/reef knot
- One-handed square/reef knot
- Surgeon’s/friction knot (two- or one-handed) – double 1st loop
- Instrument tie
- Granny knot occurs with incorrect crossing of strands, slips with subject to pressure
Biopsy and Fine Needle Aspiration
US or CT guided.
For FNA can use needle through a guide needle, needs to be at least 3cm longer. 20G 9cm spinal needle guide takes a 25G 15cm needle. 20G 15cm guide takes a 25G 20cm needle. 17G guide needle takes an 18G core biopsy needle. Steristrips to mark needles at point where they just protrude through guide needle.
Lung biopsies O2 30min prior to biopsy.
Gastrointestinal and Hepatobiliary Intervention
Nasogastric Tube Insertion
Sniff anaesthetic gel into best nostril, spray throat w anaesthetic spray, if anxious mild sedation. Cross-table lat pharynx during insertion. If difficult, Hinck catheter angled post and larynx, may catch in pyriform fossae; when in stomach moistened exchange wire then NGT. Glidewire may be needed for soft silicone NGTs, with some tap water into tube to keep it slippery.
Liver biopsy principles and techniques
Get patient to breathe in and hold. Usually go into right lobe of liver subcostally, avoiding vessels/biliary tree. Liberal LA at liver capsule. 16G Quick-core, at least 1 good sample. Difficult to breach liver capsule, need to make sure breach capsule before taking biopsy to avoid tenting and thus stretching the capsule too much = painful.
Percutaneous Biliary Drainage
For relief of obstructive jaundice assoc w pruritis, cholangitis w sepsis, brachytherapy access, failed endoscopic biliary drainage or surgically altered anatomy . Obstruction from extraluminal compression or intraluminal calculus, sclerosing cholangitis, prev procedure, ischaemia, cholangiocarcinoma, pancreatic Ca, ampullary Ca, mets, lymphadenopathy. Prophylactic ABs (high risk of bacteraemia). Approach 2cm post to midaxillary line @ 11th intercostal space, or subxiphoid > peripheral bile duct. Guidewire insertion and dilation of tract. Locking loop catheter if biliary tree not traversed, drainige for >1day to resolve local oedema and distension before further attempt. Past obstruction, biliary drainage catheter inserted w locking loop in duodenum. Flushed BD-TDS w 10mL sterile saline, catheter exchange every 3/12. Cx sepsis (overdistended infected biliary system), haemorrhage, bile leak, cholangitis, catheter dislodgement, malfunction, fluid/electrolyte imbalance, Px.
Self-expanding metal stent for malignant disease to negate need for external drainage. Balloon dilatation w high pressure or cutting balloon prior (very painful). Tumour ingrowth via interstices or margin overgrowth > recurrent obstruction.
Biliary drainage post lapraoscopic cholecystectomy injury for bile diversion from leak. May be diffuclt with decomressed biliary tree from CBD transection. Drain into biloma.
For calculus/acalculous cholecystitis in unstable patients, usually temporary until cholecystectomy performed. Prophylactic ABs. Transhepatic approach preferred so leak around needle/catheter is extraperitoneal. If pt not for surgery, leave for 6/52 for tract maturation prior to tube cholangiogram (ensuring cystic duct and CBD patency, absence of calculi) prior to removal.
Transarterial Chemoembolisation (TACE)
For inoperable tumours to prolong survival, not for cure. Most mets receive blood from hepatic aa. N parenchyma 70% from portal vein, hence need to check PV patency and hepatopetal flow to preserve hepatocytes. Responsive tumours include HCC, neuroendocrine, melanoma, sarcoma, colorectal. Contraindications include PV thrombosis, biliary obstruction,; relative contraindications tumour burden >50% of liver, liver failure. Super-selective catheterisation. Distal agents (polyvinyl alcohol, calibrated gelatin microspheres) +/- cytotoxic agents, most add iopamidol and ethiodised oil. May use temporary embolic agents eg foam. Lipiodol may stay in hepatomas for 1yr, N cells <4/52. Doxorubicin for neuroendocrine tumours. Fluorouracil and mitomycin for colorectal mets. Post embolisation syndrome – release of cytokines causing pain, nausea, fever, gas; selflimiting in <5 days.
Hepatic aa injury -> proximal agents w coil embolisation as selectively as possible (to reduce infection, ischaemia, biliary stricture). Cx pseudoaneurysm, fistula, haemobilia.
(Radiofrequency RF ablation). Used for cure or debulking. RF waves -> ionic agitation -> heating >60deg -> coagulative necrosis and cell death. performed via US, CT or MRI guidance. Relative contra-idications is proximity to diaphragm/kidnesy/gallbladder (can infuse dextrose between), vessels (acting as a heat sink, cann perform hepatic vein balloon occlusion).
Transjugular Intrahepatic Portosystemic Shunt (TIPS)
For life-threatening portal venous HTN (variceal bleeding, intractable ascites), hepatic hydrothorax, hepatorenal syndorme, Budd-Chiari syndrome. Side-to-side anatomosis, usually betw right hepatic and portal veins. R hepatic vein accessed via R internal jugular, curved needle passes made anteriorly to R portal. From middle hepatic passes made post. Pressure gradient measured. Portal venography to assess access point and length of tract. Balloon dilatation of tract, then stent deployment (typically 10mm covered stent). Covered stents prevent thrombosis from exposure to parenchymal tract, but may trap bronches of portal vein or IVC. Portosystemic pressure gradient and venography repeated. Aim to reduce to <12mmHg to prevent filling of varices, <15mmHg for ascites. Varices may also be embolised w coils. Contraindications severe hepatic failure, severe right heart failure; relative in polycystic liver, hepatic CA, hepatic encephalopathy, portal vein thrombosis. Cx intraperitoneal haemorrhage, haemobilia, sepsis, transient renal failure, worsening encephalopathy (in 25%, but controlled medically in most). <br>
1yr patency 20-66%. Early shunt malfunction often asymptomatic. US surveillance for shunt stenosis or occlusion (US pre-TIPS for anatomy/haemodynamics, within 24h of procedure, 3/12, then every 6/12), transjugular portal venograms at 6/12, 1yr then annually. US using 2.5-3.5MHz, greyscale for size/echotexture of liver and spleen; spectral and colour of main/right/left portal veins, hepatic veins and IVC for patency and direction of flow; velocity measurements in main portal vein and hepatic aa; check for enlarged colateral vessels, ascites; duplex interrogation of stent (PSVs and portal ven end, mid-stent and hepatic vein end). Normal postshunt velocities 100-200cm/s. In 2/3 blood flow in R and L portal veins reverse (hepatofugal) with diversion to stent. Portal vein velocities increase. Shunt malfunction from thrombosis or pseudointimal hyperplasia (within few weeks, ->stenosis within 6/12, usually focal commonly hepatic vein end). Almost all stenoses cause reduced velocity (preferential shunting through collateral veins), but may be high-velocity. Duplex ~100% sensitive for occlusion. Transjugular portograph +/- shunt revision if temporal stent velocity change >50cm/s, shunt velocities <90 or >190cm/s, portal ven velocity <30cm/s, recurrent/new/incraesed of ascites or collateral pathways, return of hepatopetal flow in R/L portal veins.
Partial Splenic Infarction
Indications splenomegaly (haemolytic anaemia, splenic vein thrombosis, PV HTN, tumour, infiltrative diseases, myelofibrosis, polycythaemia vera) causing anaemia, thrombocytopaenia, discomfort, gastric varices from splenic vein thrombosis. Pneumococcal vaccine prior. Embolisation distal to pancreatic brancheswith distal agent to ablate 60-70% of splenic tissue. Cx pancreatitis, splenic abscess (> surgical splenectomy).
Indications ureteral obstruction, renal stones, for dilatation of strictures, brush biopsies, urinary diversion for closure of fistulas, pyelonephritis to prevent overdistension > bacteraemia. US + fluoroscopy or CT guidance. Requires renal dilatation to proceed. Always give IV ABs, sedation (if able), pulse oximeter (O2 if sats <90). Prone. LA esp under skin and renal capsule w spinal needle. Puncture in middle of lumbar window (borders paraspinal ms, iliac crest, 12th rib, post ax line) down barrel of post calyx directing towards renal pelvis @ 30-450 to vertical (avalscular plane of Brodel, usually ant-med-sup) of mid/lower pole, below 12th rib or lower 11th intercostal space to avoid Px. Nick skin then puncture calyx w 18G needle (21G requires more catheter/wire exchanges). Ensure needle tip positioned within calyx, aspirates urine, confirm with nephrostogram. Guidewire placed as far as possible (ensure at least all of floppy part inside kidney). Dilate to 1Fr more than nephrostomy catheter (usually 10Fr tube, 11Fr dilator). Cope-lock catheter into renal pelvis, pull out wire, pull string and twist to allow loop formation, lock string. Antegrade nephrostogram for confirmation, detect leak and cause of hydronephrosis. Anchor suture. Usually changed every 12 weeks to prevent encrustation and occlusion. Cx haemorrhage, sepsis, pneumothorax, urinoma, visceral injury (colon, liver, spleen), catheter malfunction.
To replace tube cut catheter just below rubber flange, insert 0.038 Bentson wire (usually straightens loop), later inserting as same time as withdrawing catheter. May need stiffer guide. Cope-lock catheters have string inside maintaining loop, if encrusts catheter can be hard to remove. Difficult cases peel-away sheath 1 Fr larger than neph tube cut just shorter than amount of tube protruding; rotate down over the tube and pull tube through it. If wire doesn’t pass through use stiffer wire (Extra/Super-stiff Amplatz), if still not then can try peel-away sheath or try stiff end of wire advancing as far as it will go then pull back tube to puncture tube and remove. If string from Cope loop catheter lodged in tract, cut end of 5 Fr Hinck 10mm shorter than protruding thread, pass it down thread as far as possible which usually then loosens and able to be removed. May require extra suture tied to thread end to make it long enough. If wire lost out of tract, can retreive tract if >3/7 old – outline w contrast into skin hole, Terumo glidewire (held by wet gauze) manipulated/rotated down visible tract, then catheter.
Percutaneous Stone Extraction
(Percutaneous nephrolithotomy). Calyx with best access to stone chosen. May need two sites if large staghorn calculus. Distension may be needed via contrast via retrograde ureteral stent or antegrade nephrostomy. ‘Saftey wire’ through to bladder before dilatation of tract up to 30F.
Antegrade Ureteral Stent/Dilatation
For identification of ureter during surgery, bypass of obstruction. Ureteric strictures from trauma, tumour, TCC in trigone, cervical Ca. Access via midpole calyx easier for ureteric access. May need to wait for few days of drainage after nephrostomy if significant bleeding, oedema, ureteric tortuosity or difficult crossing of obstruction. Double J stent requires cystoscopic exchange every 3/12. May need balloon dilatation w 5-6mm high-pressure balloon +/- cutting balloon, allowing passage of stent. Cx perforation, bladder irritation, catheter dislodgement, encrustation/occlusion, incorrect positioning.
Uterine Fibroid Embolisation
Uterine artery embolisation for symptomatic (bleeding, bulk-related Sx, pain_ leiomyomas (cf myomectomy, hysterectomy). MR for size and position of fibroid and other patholagies, incl contrast for vascularity. Bleeding assoc w submucosal component of fibroid or adenomyosis. Pain/bulk-related Sx assoc w transmural/subserosal fibroids. Branches of uterine a (cervical, ovarian) evaluated to prevent nontarget embolisation. Particles used to spare supply to N myometrium. High risk of postembolic syndrome (pain, fever), Rx anti-inflammatory agents, narcotics. Follow-up MR for vascularity, size change w 20-40% reduction and lack of enhancement in 3/12 expected for success. Cx elayed infection w submucosal fibroids (esp large pedunculated fibroids), early menopause, uterine necrosis, nontarget embolism, unknown fertility effects.
- Pulmonary angiography – 5/7Fr multi-sidehole pigtail catheter in right ot left PA via CFV, IJV or brachial/axillary vein. PA pressure reflects RH function. Non-ionic, low osmolar contrat has reduced complicatiosn and cough reflex. At least 6 frames/sec. Cx increased with PA HTN (SP>30mmHg) incl RH strain, arrhytmias, cardiac perforation, cardiac arrest, respiratory insufficiency. Contraindicated in high PA pressures and LBBB (risk of RBBB entering RH > total heart block). Indications trauma, congenital anomalies, tumour encasement, primary PA HTN, vasculitis, stenosis, PE, PAVMs. 2-5% morbiditly, <0.5% mortality from sudden RV failure due to increased PA pressure with contrast injection.
- Bronchial arteriography – Bronchial anatomy very variable, 1 R 2 L in 40%, 1R 1L in 30%, 2R 2L in 25%, transpleural arterial collaterals (from intercostals, SCA braonches, internal mammary, axillary a brainches, esp prior bronchial embolotherapy, cause of massive haemoptysis in 50%). Arise from T4-T9 thoracic aorta or with intercostal artery (broncho-intercostal artery, beware artery of Adamkiewicz). Indications haemoptysis (planning for embolotherapy), embolic obstruction of PAs, congenital cardiopathy w interrupted PAs, Ix for lung transplant, pulmonary sequestration.
- Bronchial embolotherapy usually using coaxial system microcatheter or directly. Usually particles (polyvinyl alcohol sponge > precapillary level) reducing shunting > PV and preseve capillary flow to critical organs (lungs, tracheobronchial tree, visceral pleura, oesophagus). Coil embolisation promotes collateral flow distally. Repeat pulmonary haemorrhage in 15-25% in 1st yr.
- Cerebral arteriogram – Catheterisation of internal carotids and usually L vertebral. Hinck with Bentson or Terumo. Unfolded aortas have more acute angle into great vessels > Mani or sidewinder catheter w Terumo glidewire well in carotids to angle of jaw. In difficult catheterisations, deep breath helps straighten carotid aa. Double flush with heparinised saline. The longer contact time of iodinated contrast with vessl increases risk of seizure and thrombus etc. 0.5-1% risk of permanent stroke.
- Carotids – roadmap of bifurcations in lat > guidewire then catheter into ICA 30-40mm (if not stenotic). If narrowed do injection in CCA. 8mL@6mL/s.
- L vertebral – roadmap of L SCA. Proxiaml vertebral aa can be very tortuous, hence best not catheterised unless essential. 8mL@6mL/s.
- Arch and carotid arteriogram – 5Fr pigtail catheter > mid asc aorta. Injection 40mL@20mL/sec. Carotid catheterisations as per cerebral angiograms, but tip 40mm below angle of jaw.
- Trauma arch – always use Bentson wire, if catches in prox desc aorta is very suspicious of a tear (hence may stop). Keep at lesat 80mm wire out at end of catheter, only advancing catheter near arch if wire in asc aorta. May need eschange wire to get pigtail catheter in. Injection 40mL@20mL/sec, LAO 30 and RAO 20 +/- AP, lat.
- Axillary arteriogram – Femoral puncture, Hinck + guidewire > SCA 20m distal to vertebral. For vertebral origin visualisation rely on reflux rather than pulling back as cather tends to recoil into arta during injection. 16mL@8mL/sec.
- Brachial arteriogram – Hinck catheter. SCA to check for thoracic outlet lesion (assopc embolism) w sohulder abduction views. Catheter needs to be prox to upper 1/3 humerus (brachial aa and branches prone to spasm). Check before injection as is easy to inadvertebtly enter branches. Distalforearm and hand do long series of films ans flow can be slow esp Reynauds.
- Renal arteriogram – Initial aortic injection (upper L1, 30mL@15mL/sec pigtail or 24@12 for Halo catheter; true AP placing SMA over aorta) may be sufficient to exclude renal artery stenosis, selective injections only if required (R&L required for donor kidney workup). If SMA obscures renal aa, can withdraw 20-40mm or slow injection (20@12 for pigtail). Best view of renal aa origins is LAO 15-30. Selective renal aa injections using Sim 1 or Cobra 10-20mm into a; 10@6.
- Mesenteric arteriogram – For ?ischaemia lat aortogram for coeliac/SMA origins, pigtail catheter 30mL@15mL/sec, then > selective angiograms with Sim 1, 10-20mm into coeliac, 20-30mm into SMA. Obesity better with Cobra or Visceral. Consider Buscopan IV to reduce peristalsis. Coeliac and SMA ischaemia 20mL @ 7mL/sec, GI bleed 28mL @7mL/sec. IMA flow slower, tends to spasm, 10-15mL @2-4mL/sec.
- Femoral arteriogram – 4F pigtail catheter 15mL@12mL/sec (incr to 20@12 for tibial vessels). Puncture side contralateral to weak femoral pulse or calf claudication, or for thrombolysis or angioplasty. Can use initial pigtail catheter pulling loop from lower thoracic to lower aorta directing wire down contralateral iliac. Otherwise Omni catheter, or Sm 1 for acutely angled bifurcations.
In trauma it is easiest to do ipsilateral upstream (downstream may > profunda), alternatilvely contralateral puncture (>Omni or Sim1 with exchange for Hinck to pass below groin).
Haemodialsis via ateriovenous fistula (AVF, Cimino-Brescia fistula, usually in forearm), bridge graft fistula (loop or straight using PTFE/polytetrafluoroethylene or bovine vein when native veins inadequate), central venous catheter of dialysis port. AVFs use native veins, last for years; Cx haematoma, pseudoaneurysm, stenosis, thrombosis.
AV or bridge graft fistulas require monthly monitoring recommended with aim to intervene prior to thrombosis. High venous pressure suggests venous anastomotic stenosis. Percutaneous thrombectomy of grafts with mechanical thrombectomy devices, balloon thrombectomy or thrombolytic agents.
Percutaneous Venous Access
Temporary or ‘permanent’, tunnelled or non-tunnelled. Cx venous thrombosis, obstruction by impingement againse wall, cava stenosis, occlusion of catheter, air embolism, access site bleeding, vessel injury, pneumothorax.
- Triple lumen catheters.
- Peripherally inserted central catehters (PICCs) via brachial, basilic or cephalic vv > cavoatrial junction to reduce subclavian venous thrombosis, for up to 4/52 use.
Tunnelled access for >4/52, occ >1yr. Via external jugular (size, easy access position). Cx from subclavial access incl pinch-off syndrome (compression betw clavicle and 1st rib), subclavian stenosis.
- Hickman catheter – single lumen adequate for ABs, multi-lumen for TPN. Large catheters (12-16 Fr) for dialysis where high flow req’d. Distal lumens offset to prevent blood mixing (to prevent recirculation of dialysate). US check for vein patency. Analgesia and sedation. LA. Skin nick. Needle with syringe of saline into medial aspect of incision, puncture jugular vein then withdraw while aspirating. Once blood aspirated, angle needle horizontally, pass wire into IVC under fluoro. Remove needle. LA down tract, horizontal incision down tract, forceps down tract, Hickman passed with cuff in mid tract. Line catheter down SVC, cut to length via fluoro. Dilate then peel-away sheath w dilator down wire. Remove dilater and wire holding thumb over sheath. Catheter down sheath, confirm position then remove sheath. Suture neck +/- catheter entrance. Anchor suture. Can use straight away. Sandbag tract 1hr. Skin sutures out 7/7, anchor suture out 10-14/7.
Subcutaneous ports most cost-effective for >6/12. Catheter completely under skin, prolonging life and preventing infection. Need to check for any clot in filter before retrieval. Gooseneck snare to engage hook, then constrained by a sheath before withdrawing.
Percutaneous Angioplasty and Stents
Balloon angioplasty induces media stretching and plaque fracture. Local dissection restores vascular flow. Risk of more extensive disection and thrombosis; hence anticoagulation required. Proliferative restenosis occurs in 30-50% after 4-6/12 from intimal thickening.
Stents provide a larger more regular lumen, tacking down the intinmal flaps and dissections, limit vascualr spasm. Focal erosion and endothelial disruption may induce thrombosis, hence potent anticoagulation required. Intimal thickening may lead to proliferative restenosis, reudced with coated anti-proliferative agents (paclitaxel, rapanycin) which limit smooth muscle hyperplasia.
Synthetic grafts usually polytetrafluoroethylene (PTFE, Teflon frabric), used more in larger vessels (small vessels prone to early thrombosis). Autologous vein grafts may be reversed or stripped.
Inferior Vena Cava (IVC) Filter
90% of PEs from venous thrombosis in lower limbs or pelvis. Indications of filter incl contraindication to anticoagulation, reduced cardiopulmonary reserve, noncompliance, free-floating thrombus in IVC, prophylactic in spinal injury or multiple traumatic injuries.
Insertion via R femoral or jugular vv preferred. IVC-gram for ?thrombus, anatomy, diameter. Placement just inferior to renal veins; if double IVC in each cava or single suprarenal filter. Suprarenal placement if infrarenal IVC or renal vein thrombus, gravid female (avoids compression from uterus, prevents emboli via ovarian vein). Cx recurrence of PE 3-4%, caval thrombosis 3-9%, filter migration, perforation, tilting, filter fracture.
Filter removal in migration of filter, filter infection, retrievable filters (within 10-14/7 to prevent endothelialisation)
Foreign Body Retrieval
Catheters from pinch-off syndrome, catheter exchange, placement misadventure. Coils lost during embolotherapy. Goose-neck snare has snare loop at right-angles to cable.
Stop meds that lower seizure threshold at least 24-48hrs prior (phenothiazines, antipsychotics, TCAs, CNS stimulants, MAOIs, lithium). Prone, needle 20-30mm off midline at L2-3 and angled to course under lamina; or bolster or rotated so needle stright down under lamina. Avoid midline betw spinous processes as when prone needle tip will end up at disk level (usually most stenotic location). 1st pop passing post ligaments, then 2nd pop entering thecal sac. Max 3.06g of iodinated contrast; ~ 12mL of 240mg/mL. Few minutes on each side prior to scanning.
Cervical or thoracic myelography safer to be done via lumbar approach then tilting downward but head in hyperextended position, under fluoroscopic guidance.