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P. Jamieson and A. K. Allouni

tissues to the cuff, therefore preventing line migration. Haemodialysis lines are most commonly two separate lines, with tips placed approximately 3 cm from each other, whereas Hickman lines, used for venous sampling and administration of medication, can be single or dual lumen within a single line.

Ports feature the same silicone or polyurethane line that sits within the chosen vein, but instead is attached to a titanium or plastic chamber with a self-sealing septum that sits immediately below the skin.

Other Components oftheInterventional Radiology Trolley

• Sterile drapes for the procedural trolley.

• Antiseptic scrub for the procedural site, such as chlorhex-

idine soaked gauze, or ChloraPrep sticks.

• Sterile drapes for the patient. Typical these contain a fen-

estration for arterial access, with specic shapes for fem-

oral, brachial or radial access. Standard rectangular drapes

can be used to extend where necessary.

• Sterile coverings for protective lead screens, the image

intensier and any other controls.

• Sterile ultrasound probe covers.

• A closed system with a 3-way tap, connected to heparin-

ised saline, contrast and a waste drainage bag for egress.

• Basin containing heparinised saline for wires/catheters.

• Gauze.

• Syringes.

– At least 2 for heparinised saline ushes, 2 for contrast

and 1 for lidocaine. These syringes should be visually distinct, at a minimum through labelling, but now more commonly by syringe colour or shape.

– Smaller syringes will also be required if microcathe-

ters are in use.

• Scalpel—for skin incision.

• Mosquito/forceps—for use separating supercial soft tis-

sues. Can also be used to x lines to drapes.

• Towel clips, for xation of ultrasound probes, lines,

drapes.

• Flow-switch—device that can be attached to catheters

and opened to allow passage of wires and uids or closed

to prevent this occurring.

• Sharps pad, for safe storage of sharps.

Personal Protective Equipment

• Lead gowns.

– Two piece gowns with a separate top and skirt spread

the load onto the hips and reduce the weight transferred through the back.

– 0.25–0.35mm lead-equivalent thickness, often with a

wraparound design that doubles the protection on the front of the body

• Lead thyroid shield.

• Lead glasses.

• Lead caps and gloves are also available, but their use is more heterogeneous.

• Appropriate radiation monitoring.

• Sterile gloves and gown.

• Face mask or shield to reduce the risk of splash injury.

• Hanging, lead-lined Perspex screen that can be easily re-positioned.

• Floor-standing lead screen.

• Table-mounted lead apron.

Common Medications Used During Endovascular Procedures

Local anaesthetic is adequate for the majority of endovascular procedures, with different agents providing a range of action onset and duration. The same agents can also be administered as regional anaesthesia, such as a sciatic nerve block that can enable a patient with considerable rest pain to remain still during lower limb revascularisation. Co-administration with adrenaline/epinephrine serves to delay absorption (reducing the risk of systemic toxicity) and prolong the duration of action.

– Lidocaine has a rapid onset of action (<5min) and a dura-

tion of action of 1–2h. It is most commonly used as a 1% preparation but exists up to 4% strength. Maximum dose is 4.5mg/kg (300mg in a 67kg individual, or 30mL of 1% lidocaine), or 7 mg/kg when delivered with epinephrine.

– Bupivacaine has a slightly longer onset of action (8min)

and is more painful on administration but provides anaesthesia for 4–8h.

Antiplatelets

There are no clear recommendations regarding the optimal regimen of antiplatelets with regards to peripheral arterial disease, but the Transatlantic Inter-Society Consensus (TASC) guidelines do recommend antiplatelet therapy is started prior to and continued following endovascular or surgical vascular procedures. Many centres will commence 3–6 months of dual antiplatelet therapy following infrainguinal stent placement. Unless the appropriate antiplatelet is commenced 1 week prior to the procedure, a loading dose

5 Basic Tools andTerminology forEndovascular Interventions

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of 300mg of aspirin or clopidogrel should be given on the day of the procedure, followed by a maintenance dose of 75mg daily.

Heparin

– For prevention of thromboembolism. – Often administered during angioplasty or stent deploy-

ment procedures following secured arterial access, due to the risks conferred by temporary occlusion of blood ow during angioplasty and the risks of distal embolisation. Dosing is typically a bolus of 50IU/kg up to a maximum of 5000IU, with 1000IU maintenance dosing hourly, but more accurate maintenance of anticoagulation can be assisted through measurement of activated clotting times (ACT) and maintenance in a range of 300–400s.

– Short-acting heparin is also used as bridging therapy for

patients on long-term anticoagulation, or for treatment for those with acute ischaemic events, and cessation of these takes place in the hours prior to the procedure, depending on the mode of administration.

– A rare but signicant complication of heparin administra-

tion is immune-mediated heparin-induced thrombocytopaenia, which can cause life-threatening thromboembolic complications. Bleeding is a risk, as with any anticoagulant.

Heparinised saline is used for irrigation of angiographic equipment and the ushing of angiographic catheters and sheaths. It is formed by mixing 1IU of heparin per mL of normal saline. It can be set up with a pressure bag for continuous ushing, with particular utility when long sheaths are used.

Tissue plasminogen activator (TPA, Alteplase) is a thrombolytic medication used in the treatment of acute limb ischaemia, as well as for acute myocardial infarction, pulmonary embolism and ischaemic stroke. It can be infused directly into thrombus through use of a side-holed catheter that ideally traverses the thrombus. Thrombolysis is contraindicated in patients with known active bleeding, recent surgery or a known intracranial neoplasm. Streptokinase and urokinase are older brinolytics, but its use is more historical due to the signicant risk of allergic reactions.

Antibiotics may be required as prophylaxis, most commonly in the context of interventions involving a prosthetic graft, or in some centres, for tunnelled line insertions. Local policy for antibiotic choice should be consulted.

Vasodilators can be used therapeutically to treat arterial or venous spasm, or prophylactically prior to intervention within vessels high-risk for spasm, typically smaller vessels such as the infrapopliteal or visceral arteries.

– Glyceryl Dinitrate (Isoket) – Glyceryl Trinitrate (GTN)

Antihypertensives

Hypertension is common in patients with peripheral arterial disease (PAD) and is more likely to be poorly treatment is PAD patients than the general population. It presents a considerable cardiovascular risk factor and contributes to progression of PAD.

Conscious Sedation

• Midazolam—benzodiazepine—induces sedation, anxiolysis and causes amnesia. Can be administered IV, typically as a bolus of 0.5–2mg and maintained with further boluses 25% of the original dose every 30–60min. It can also be given intramuscularly pre-procedure.

• Fentanyl citrate—a potent analgesic and sometimes coadministered with benzodiazepines for sedation—administered IV, typically in 25–50μg aliquots every 15–70min. Use with caution in patients pre-disposed to respiratory depression.

• Safety—conscious sedation, judicious use, especially when benzodiazepines and opiates are used in conjunction, as there is considerable risk of respiratory depression.

– CO2 capnography, or end-tidal carbon dioxide, pro-

vides earlier warning signs of respiratory depression than oxygen saturation and should be utilised when sedatives are administered.

– Oxygen should be available along with masks and

delivery conduits such as masks or nasal prongs.

– Airway adjuncts and/or supraglottic airway devices

and ventilation equipment may be required in the event of over-sedation.

– Reversal agents—naloxone 0.4–2mg IV, repeated at

2–3 min intervals (opiates), umazenil (benzodiazepines).

Contrast Media

The most common contrast media used during endovascular procedures are low-osmolality iodine-based, such as Iohexol (Omnipaque, GE Healthcare), often used at strengths of 240–350 mg of iodine per mL. These agents provide the highest quality invasive angiographic imaging. Consideration the patient’s allergy history and have access to medication and equipment required in the treatment of anaphylaxis.

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P. Jamieson and A. K. Allouni

Consider the patient’s renal function and the need for preand post-procedural hydration.

Carbon dioxide-based angiography is an alternative to iodinated contrast in patients with iodinated contrast allergy or renal dysfunction, but is more complex to use, incurs higher radiation dose, is limited by overlapping bowel gas and is often more uncomfortable for patients.

Gadolinium-based contrasts agents, such as those used in MR imaging (e.g. Dotarem, Guerbet), can be used in a similar manner to iodinated contrast in patients that are iodineallergic, but is of lower density and only safe in much smaller volumes (10–20mL). It is not safe in patients with signicant renal dysfunction due to the risk of nephrogenic systemic brosis.

Anaphylaxis

– Indicated by soft tissue angio-oedema, bronchospasm,

rash and cardio-respiratory compromise.

– Call for help and the local resuscitation team. – 0.5mg Adrenaline IM (0.5mL of a 1:1000 preparation).

Repeat after 5min if no response. Lower doses in children

<12years.

– Give oxygen and maintain the airway with adjuncts if

required.

– IV uid bolus of 500–1000mL. – Nebulised adrenaline or nebulised salbutamol/ipratro-

pium may be required for persistent upper airway obstruc-

tion or bronchospasm respectively.

Imaging Equipment

Do we want to include this? E.g. generators, X-ray tubes, tables, c-arms.

While ultrasound is used for vascular access, and occasionally for other percutaneous procedures such as the injection of thrombin, most endovascular procedures are performed under the guidance of uoroscopy. Pulsed uo- roscopy, typically between 2–7 frames per second, provides “real-time” X-rays images. Digital subtraction angiogra- phy is a technique by which an initial mask image is subtracted from the live image, therefore showing only what is new or has changed since the mask image, most importantly contrast agents.

Generators provide electrical energy for X-ray generation and control X-rays. The quality of images is determined by various factors such as tube voltage, tube current, pulse width, pulse rate, focal spot size, beam ltration and dose rate. Dose rate (measured in μGy per image) is determined by kVp, mA and pulse width, changes in which reduce image noise but

increase dose to the patient (and the operator). Generators adjust radiation by adjusting tube current, pulse width and tube voltage, in that order, optimising radiation output for different types of angiographic studies and patient sizes.

X-ray tubes are formed of a tungsten lament cathode and a tungsten anode disc, converting kinetic energy of electrons into X-rays (and heat). Collimators are attached to the X-ray tube and comprise beam-blocking facets that shape the beam at exit from the tube, and wedge lters that can alter the strength of emitted radiation to optimise image quality and reduce patient dose. The image chain is more often a at-panel detector than an image intensier on more modern machines. It converts the received pattern of transmitted X-rays into a live image that is displayed in real time.

The gantry stand holds the X-ray tube and the image chain. The C-arm is the most common design used for new equipment. Single-plane gantry stands can be ceiling or oor-mounted, while in biplane congurations the lateral plane is mounted on ceiling rails and the frontal plane assembly is mounted on the oor. Rotational angiography and cone-beam CT are possible with gantries that have a true isocenter.

Patient tables are often composed of carbon bre to permit maximal strength with minimal beam attenuation. Tabletops move axially relative to the patient and can be raised or lowered, which alters magnication, eld of view and dose. Many tables also permit a degree of tilt.

Displays should show live uoroscopy with a second screen or partition that displays a reference image or roadmap, with information on patient dose and screening times. A biplane system will require live and reference imaging for both the frontal and lateral projections. There should also be provision to display patient observations, and some will offer display or alternative imaging such as previous crosssectional imaging or radiographs.

A contrast pump injector can control contrast injection for angiography. On modern machines, it is linked to the X-ray machine to allow synchronisation for digital subtraction angiography, with the ability to alter pump or X-ray delay to match DSA timing with the expected progression of contrast. The machine can control injection volume and injection rate.

Basic Terminology

Acute Limb Ischaemia Plaque rupture or an embolus leads

to abrupt lack of blood ow to the arms or legs, presenting

with symptoms such as pain, coldness and pallor.

Amputation Surgical removal of a limb or other body part. Aneurysm A bulge or swelling in a blood vessel that can

rupture and cause life-threatening bleeding. A true aneu-

5 Basic Tools andTerminology forEndovascular Interventions

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rysm is contained by all three layers of wall; a pseudoaneurysm is not.

Ankle Brachial Pressure Index (ABPI) A test used to

diagnose peripheral artery disease by comparing blood pressure measurements in the arm and ankle.

Angiodysplasia A condition in which abnormal blood ves-

sels in the gastrointestinal tract can cause bleeding.

Angiography A medical imaging technique used to visual-

ise blood vessels using X-rays, CT or MRI. X-ray and CT angiography utilises a contrast agent, MR angiography can be performed with or without a contrast agent.

Angioplasty A procedure used to widen the lumen of nar-

rowed or blocked blood vessels using a balloon catheter that is inated at the site of the stenosis or blockage. Short for percutaneous transluminal angioplasty (PTA).

Antiplatelets Medications such as aspirin, clopidogrel and

ticagrelor that prevent platelets from sticking together and forming clots.

Arteriovenous Fistula An connection between an artery

and a vein, which can be intentional, typically used for dialysis access, or can be abnormal and cause problems such as bleeding or cardiac failure.

Artery A blood vessel that carries oxygenated blood away

from the heart to the body’s tissues and organs.

Atherectomy A procedure used to remove plaque from the

walls of arteries, typically using a catheter-based device.

Balloon Catheter A catheter with a balloon at the end that

can be inated to widen the lumen of narrowed or blocked blood vessels during angioplasty, to occlude vessels or to mould stent grafts.

Bypass A surgical procedure used to reroute blood ow

around a blocked or narrowed blood vessel. Autologous veins or prosthetic grafts of plastics such as PTFE are used.

Catheter A thin, exible tube normally advanced over a

guidewire, used to deliver contrast agents, uid, or medications and to provide support for guidewires.

Chemoembolisation A treatment for cancer in which

chemotherapy drugs are delivered directly to a tumour through arteries, often through use of embolisation particles impregnated with the chemotherapy agent, commonly used for hepatocellular carcinoma. Also known as transarterial chemoembolisation, or TACE.

Chronic Limb Threatening Ischaemia (CLTI) Also

known as critical limb ischaemia. Longstanding peripheral artery stenoses or occlusions lead to ischaemic symptoms in the limbs such as pain at rest, non- healing wounds or gangrene.

Claudication Pain or cramping in the legs caused by inade-

quate blood ow to the muscles during exercise. It ceases when resting.

Coil Embolisation A procedure used to treat bleeding, aneu-

rysms, or other vascular abnormalities, in which small

metal coils are deposited, causing mechanical obstruction

and promoting clotting in order to block blood ow. Computed Tomography (CT) A medical imaging tech-

nique that uses X-rays and computer processing to create

detailed cross-sectional images of the body. In the con-

text of endovascular imaging, iodinated contrast is almost

always given. Contrast Agent A substance injected into the body to make

certain tissues or blood vessels more visible during medi-

cal imaging. Iodinated contrast is used for CT, whereas

gadolinium-based contrast is used for MRI. Catheter

angiography is normally performed with iodinated con-

trast, though gadolinium can also be used, a carbon diox-

ide can be used as a negative contrast agent. Catheter-Directed Thrombolysis A procedure to dissolve

blood clots using a catheter and a brinolytic agent such

as alteplase. This is often through a slow infusion that

lasts for 24h or more. Central Venous Catheter A catheter placed in a large vein

in the neck, chest, or groin to administer medications, u-

ids, or nutrition, the facilitate dialysis, or to permit venous

sampling. Central venous catheters can be tunnelled under

the skin for a short distance to reduce infection risk and

increase longevity. Deep Vein Thrombosis A blood clot that forms in a deep

vein, most commonly in the legs, presenting with pain,

limb swelling and/or erythema. Digital Subtraction Angiography A type of imaging that

involves the computerised subtraction of a mask image

from future images that contain a contrast agent, demon-

strating the contrast ow in more clarity. Dissection A tear in the intima, the inner layer of an artery

or vein. This can cause separation of the intima from the

other layers of the vessel wall, potentially narrowing or

obstructing the lumen. Embolisation A procedure used to block or reduce blood

ow to a selected part of the body, using substances such

as particles, coils or plugs. Embolectomy A surgical procedure used to remove a blood

clot from an artery, often using a balloon catheter. Embolus A blood clot, air bubble, fat locule or foreign

material that travels through the bloodstream and blocks

a blood vessel. Endoleak A complication that can occur after endovascular

repair of an aneurysm, most commonly abdominal aortic

aneurysms, in which perfusion of the aneurysm sac per-

sists following treatment and can present a continued risk

of rupture. Endovascular Aneurysm Repair A minimally invasive

procedure used to repair an aneurysm from within the

blood vessel, typically using a stent graft (covered stent). Fibroid A non-malignant tumour that grows in the uterus

and can present with menorrhagia or pressure symptoms.

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P. Jamieson and A. K. Allouni

In some circumstances, they can be treated with uterine artery embolisation.

Fluoroscopy A medical imaging technique that uses X-rays

to create real-time images of the body.

Gastrointestinal Bleeding Bleeding that occurs in the

digestive tract, typically due to ulcers, angiodysplasia or cancer. It can present with haematemesis, rectal bleeding or haemodynamic instability.

Graft A synthetic or natural material used to replace or

repair damaged tissue or blood vessels. This can refer to surgical bypass grafts or to covered stents that are often referred to as “stent grafts”.

Haematoma A collection of blood outside of a blood ves-

sel, typically caused by vessel injury.

Haemorrhage Excessive bleeding, either internally or

externally.

Heparin A medication that prevents blood clots from form-

ing by inhibiting the activity of clotting factors.

Hypertension High blood pressure, which can cause dam-

age to blood vessels and increase the risk of cardiovascular disease.

Inferior Vena Cava (IVC) Filter A device placed in the

IVC to prevent blood clots from reaching the lungs and causing a pulmonary embolus.

Interventional Radiology A medical specialty that uses

imaging techniques to guide minimally invasive procedures to diagnose and treat a variety of conditions.

Intravascular Ultrasound (IVUS) An imaging technique

that uses an ultrasound probe on the tip of a catheter to create images of the inside of blood vessels.

Ischaemia A lack of blood ow to a part of the body, lead-

ing to hypoxia, typically due to narrowing or occlusion of blood vessels or due to hypovolaemia.

Magnetic Resonance Imaging (MRI) A medical imaging

technique that uses a strong magnetic eld to create signal emission from the body, which is captured and processed to form cross sectional images. It provides better contrast resolution than CT without the limitation of ionising radiation, but images are of lower spatial resolution and take longer to acquire.

Mycotic Aneurysm An aneurysm caused by a bacterial

infection.

Necrosis Death of tissue due to lack of blood ow and tissue

hypoxia.

Percutaneous A medical procedure that is performed

through the skin rather than through an open incision.

Peripheral Arterial Disease (PAD) A condition in which

the blood vessels in the legs or arms become narrowed or blocked, causing pain, numbness or tissue loss.

Plaque A build-up of cholesterol, calcium, and other sub-

stances in the walls of arteries, leading to luminal narrowing and reduced blood ow.

Portal Hypertension A condition in which high blood

pressure in the portal vein which carries blood from the

digestive tract to the liver can cause complications such

as variceal bleeding. This is most commonly secondary

to liver cirrhosis, but can also occur due to portal vein

thrombosis. Transjugular intrahepatic portosystemic

shunt (TIPSS) (see below) is a potential treatment. Pulmonary Embolism (PE) A blood clot that travels to the

lungs, causing shortness of breath and chest pain and can

be life-threatening. Renal Artery Stenosis Narrowing of the renal arter-

ies, which can lead to reduced renal function and/or

hypertension. Sclerotherapy A treatment that uses an injection of a scle-

rosing agent to obliterate vascular abnormalities such as

varicose veins, varicocoeles or vascular malformations. Selective Internal Radiation Therapy (SIRT) A proce-

dure used to treat hepatocellular carcinoma by delivering

radioactive particles directly to the tumour through the

hepatic arteries. Sheath A thin, hollow, rigid plastic tube that sits within a

vessel to provide secure vessel access, reduced vessel

trauma during wire and catheter exchange, maintain hae-

mostasis and permit injection of saline, contrast or other

medications. Stent A small metal or plastic mesh tube that can be left

within a narrowed or blocked blood vessel to hold it open.

Vascular stents are metal and can be covered (with a PTFE

covering) or uncovered. Thrombectomy A procedure to remove a blood clot from a

blood vessel, often using an aspiration catheter or stent-

based system. Mechanical thrombectomy devices exist

for use in the peripheral vasculature.

Transjugular Intrahepatic Portosystemic Shunt

(TIPSS) A procedure to re-direct blood ow from the

portal venous system into the systemic veins, with the

intention of reducing portal pressure and mitigating the

potential complications of portal hypertension such as

variceal bleeding. A stent between a portal and hepatic

vein is used to achieve this. Tumour Embolisation A procedure used to block the blood

supply to a tumour, typically using small beads or other

particles that are injected into the arteries feeding the

tumour. Chemoembolisation is a form of this, but bland

embolisation is also useful, such as pre- operative emboli-

sation of hypervascular tumours or metastases to reduce

bleeding during surgery. Ultrasound A medical imaging technique that uses sound

waves to create images of the body, displayed in real

time. It can be used to guide procedures, such as vascular

access, and for assessments, such as lower limb vascular

assessments or monitoring of aneurysms.

5 Basic Tools andTerminology forEndovascular Interventions

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Ultrasound Duplex A form of imaging that combines ultra-

sound images with Doppler shift, providing information regarding the direction and velocity of ow.

Uterine Artery Embolisation (UAE) A procedure used to

treat uterine broids by blocking the blood supply to them using small particles injected into the uterine arteries.

Varicose Veins Enlarged, tortuous veins that are commonly

found in the legs.

Vascular Malformation An abnormal formation of blood

vessels, typically congenital, but may progress or present later in life, causing symptoms such as pain, swelling, or bleeding.

Vein A blood vessel that carries blood back to the heart.

Venous Insufciency A condition in which the valves in the

veins do not function properly, leading to the pooling of

blood and the development of leg swelling, discolouration

and/or ulceration.

References

1. Kandarpa Handbook. https://www.ncbi.nlm.nih.gov/pmc/

articles/PMC6735447/. https://www.resus.org.uk/library/

additional- guidance/guidance- anaphylaxis/emergency- treatment.

2. TASC. Complex Cases Schillinger. Learning Vascular and

Interventional Radiology, Mun~oz and Ribes. Pocketbook Clinical

IR Warhadpande. https://www.ahajournals.org/doi/10.1161/

CIRCULATIONAHA.122.059606.

Principles, Sites andTechniques

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ofVascular Access

DineshManoharan andNarayanKarunanithy

Case Presentation

A 55-year-old woman presented to the emergency department with severe abdominal pain, cachexia and diarrhoea. Previously, she had been diagnosed with chronic mesenteric ischemia as a result of occlusion of the superior and inferior mesenteric arteries, and had undergone stenting of the inferior mesenteric artery. Following a repeat CT scan and endoscopy, it was conrmed that there was an occlusion of the superior mesenteric artery and evidence of ischemic coli-

Fig. 6.1 (a) Volume rendered image from the CT scan shows aortoiliac and femoral occlusion. (b) Maximum intensity projection images showed long segment stenosis and occlusion of the superior mesenteric artery

tis as a result of poor perfusion. Furthermore, she had bilateral iliac and common femoral artery occlusions making endovascular approach challenging (Fig.6.1). The treatment plan for her was discussed in the multidisciplinary team meeting. In view of the fact that she was an unsuitable candidate for surgery, we decided to perform endovascular stenting of the superior mesenteric artery through the radial approach.

Continued at page 56

D. Manoharan (*) Department of Vascular Radiology, Shefeld Vascular Institute, Shefeld Teaching Hospitals NHS Foundation Trust, Shefeld, UK e-mail: dinesh.manoharan@nhs.net

N. Karunanithy School of Biomedical Engineering and Imaging Sciences, King’s College London, London, UK e-mail: Narayan.Karunanithy@gstt.nhs.uk

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Introduction

In 1847, German physiologist Carl Ludwig succeeded in inserting the rst catheter into an artery to study its waveform [1]. After nearly a century, another German physician, Werner Forssmann, performed the rst human cardiac catheterization by inserting a urinary catheter into his antecubital vein [2]. By the 1950s, angiography by needle puncture had become an established procedure, although it was carried out using large bore needles. As a result, its use was restricted to large arteries, vessel puncture remained difcult, and there were many complications. It was in 1953 when a Swedish interventional radiologist named Sven-Ivar Seldinger developed the technique that bears his name that resulted in the development of a safe method for accessing arteries [3].

The “Seldinger Technique” involves ve steps and is the basis for any vascular access procedure in modern medicine (Fig.6.2).

Step 1: Puncture the vessel of interest using a Trocar

needle

D. Manoharan and N. Karunanithy

Table 6.1 Suggested toolkit for vascular access

Manufacturer Size/length

Arterial access (CFA/PA/SCA)

Access Needle Any 18G/7cm Micropuncture access set

Standard sheaths Any Depending on the size of the

Fixed Core wire (J tip) Arterial access RA/BA Transradial introducer Kit

Arterial access (Tibials/Pedal) Micropuncture Pedal Introducer access set

Venous access (larger veins) Access Needle Any 18G/7cm Fixed Core wire (J tip) Standard sheaths Any Depending on the size of the

Venous access (smaller veins) Micropuncture access set

Cook Needle 21G/7cm

Wire 0.18 in/40cm Outer catheter 4 F/10cm

vessel and needs

Cook 0.021 in/180cm

Terumo Needle:

22G/21G/20G/38mm Sheath: 4 to 7 Fr/10cm Guidewire:

0.018/0.021/0.25/45cm

Cook Needle 21G/4cm

Wire 0.18 in/40cm Outer catheter 4 F/7cm

Cook 0.021 in/180cm

vessel and needs

Cook Needle 21G/7cm

Wire 0.18in /40cm Outer catheter 4 F/10cm

Step 2: Insert a guidewire and advance it into the lumen Step 3: Remove the trocar needle over the guidewire Step 4: Insert a Sheath/catheter/cannula over the guidewire

into the vessel lumen

Step 5: Remove the guidewire, and use the sheath/cannula/

catheter remaining in-situ to perform the intended procedure.

Nowadays, it is possible to access arteries and veins at various sites throughout the body for a range of procedures. This chapter describes the techniques for safe and reliable vascular access, key tips & tricks and complications to be aware of. A list of suggested hardware required is summarized in Table6.1.

Arterial Access

Common Femoral Artery

Fig. 6.2 The steps of Seldinger technique. (a) Puncture the vessel of

interest using a Trocar needle. (b) Insertion of a guidewire. (c) Removal of the trocar needle. (d) Insertion of a sheath/catheter/cannula over the guidewire. (e) Removal of the guidewire. Reprinted by permission from Cupr78up, CC BY-SA 3.0 <https://creativecommons.org/licenses/

by-sa/3.0>, via Wikimedia Commons. https://commons.wikimedia.org/ wiki/File:Seldinger.png

The common femoral artery (CFA) is the continuation of the external iliac artery under the inguinal ligament after the take-off of the deep and supercial inferior epigastric arteries (also known as the hypogastric artery) [4]. The CFA passes above the medial aspect of the femoral head before

6 Principles, Sites andTechniques ofVascular Access

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 

Fig. 6.3 (a & b): Volume rendered coronal (a) and sagittal (b) images of the right common femoral artery (CFA, between the white lines) over the femoral head. The inferior epigastric artery (white arrow) and profunda femoral arteries (arrowheads) are shown. The external iliac artery

dividing into the supercial and profunda femoral arteries. The ideal access site for the CFA is over the femoral head, which can be used to compress against for haemostasis after the procedure (Fig. 6.3). Additionally, the presence of a brous femoral sheath overlying this segment contributes to the prevention of pseudoaneurysm formation. It is important to note that access above this site has no posterior support (artery dives into the pelvis) and thus the risk of haemodynamically signicant bleeding after a suprainguinal puncture is much higher (Fig.6.3b). Typically the CFA lies between the femoral nerve laterally and the common femoral vein (CFV) medially. However, the CFA can overlap the CFV and hence posing a potential risk of arteriovenous stulas [5].

Technique

Access can be obtained by palpation only, using ultrasound or uoroscopy [6]. Blind access is done by puncturing the CFA at the point of maximum pulsation. This site corresponds to the midpoint of CFA in 92.7% of cases [7]. Use of ultrasound (US) or uoroscopy is more accurate to locate the femoral head with US-guided access proven to have fewer complications [8, 9]. Local anaesthesia (lidocaine only for short procedures and lidocaine mixed with bupivacaine for prolonged procedures) is administered to the skin and soft tissues up to the adventitia of the anterior wall of the artery. Typically, 18 G needles are used for access, and the skin entry site is 2cm below the middle third of the femoral head. From this site of skin entry, the access needle should penetrate the CFA over the middle

(star in b) can be seen diving deep into the pelvis superior to the femoral head. (c) Fluoroscopic image showing the ideal access site of the CFA over the femoral head (Black box)

third of the femoral head at about a 45-degree angle for typical ‘retrograde access’(Fig. 6.3c). A double wall penetration technique that penetrates the posterior wall of the artery and hits the femoral head is useful when performing access without US.Following this, the needle is withdrawn until blood ows back and the guidewire is inserted. A single wall puncture can now be easily performed with US guidance, which reduces the possibility of bleeding during a puncture. Furthermore, US can help avoid diseased segments of vessels to prevent complications such as dissection, plaque shift and closure device-related events [9]. US guidance also has a greater rst-attempt success rate, lower risk of venous puncture, shorter time to access and lower number of attempts [10].

Tips andProblem Solving

There is an increased risk of bleeding complications following the procedure in patients with a large body habitus [11, 12]. It may be possible to reduce complications in such patients by taping the belly so that it does not overhang the groin (or using dedicated panniculus retractor kit), using contralateral access rather than antegrade access, and using closure devices.

When accessing arteries, it is best to avoid heavily calcied wall segments. This is because achieving haemostasis after a procedure is more difcult as the arteries are more rigid, the needle makes irregular tears in the vessel wall and closure devices do not work or will be suboptimal. Additionally, displacement of plaques could result in arterial occlusion.

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For antegrade access, in addition to the above challenges, the possibility of the wire entering the profunda femoral rather than the supercial femoral artery can be encountered. Use of US guidance is highly recommended. Under US guidance, the wire can be manipulated into the SFA.Alternatively, an angiogram through the dilator to show the bifurcation point, slowly withdrawing the dilator to just above the bifurcation and then manipulating an angled hydrophilic wire into the SFA will allow suitable access to be achieved.

Radial Artery

Since Campeau rst described radial artery access in 1989, it has become increasingly popular for cardiac and neurological interventions. [13]. In recent years, it has gained wide usage for body interventions as well as more studies have shown it to be safe and effective. In RIVAL, ACCESS, RIFLE-STEACS, and MATRIX randomized trials involving more than 16,000 patients, radial artery access was associated with fewer access-related complications without any difference in stroke incidence [14–18]. As it is very easy to achieve haemostasis, radial access is particularly benecial for patients with large body habitus, thrombocytopenia, or taking anticoagulants [19]. Further, placing the arm abducted 45–90° on an arm board has been shown to reduce the radiation exposure to the operator threefold, and radial access has also been associated with better patient satisfaction, likely as a result of early mobility after the procedure [20].

Radial access does have some limitations. As a result of the smaller calibre of the artery resulting in a greater sheath/ vessel ratio, there is a slightly higher risk of vessel thrombosis and spasm. The risk is negated using the techniques described below. Another limitation is the relatively lower pushability and torqueability owing to the longer device lengths. However, newer dedicated devices are in development to address these challenges. Additionally, performing intra-procedural dynaCT may not be possible with the arm abducted and hence it may be more appropriate to keep the hand across the body during this segment of the procedure. (Fig.6.4).

Pre-Procedure Assessment

While Allen Test and Barbeau Test were historically used to assess the palmar arch, recent studies have shown that there is no significant difference in thumb capillary lactate levels, grip strength, or incidence of ischemia between individuals with normal and abnormal results [17, 21]. Hence, an abnormal Allen or Barbeau test should not preclude radial access. Nonetheless, before

D. Manoharan and N. Karunanithy

Fig. 6.4 Illustration showing alternate room set-up for left distal radial artery access. Reprinted by permission from Springer Nature: Springer Nature, CardioVascular and Interventional Radiology, Left Distal Transradial Access (ldTRA): A Comparative Assessment of Conventional and Distal Radial Artery Size, Anastasia Hadjivassiliou etal, License number: 5391931202441(2020)

access can be gained, a US evaluation must be performed to determine the calibre and rule out radial loops and blocked arteries.

Technique

Choosing between right and left radial access depends on the operator's preferences and the procedure involved. Usually, left radial access is used since it follows a straighter path into the thoracic aorta and avoids the arch, reducing the risk of stroke. It is possible to access the radial artery proximally (at the wrist) or distally (at the snuff box) (Fig.6.5). As a result of its larger calibre, it is more common to use the proximal artery, but some cases of radial occlusion have been associated with it since it causes complete occlusion of the outow throughout the procedure [22]. Since the supercial palmar arch arises before the access site, radial occlusion is rare in the distal radial artery access.

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