Endovascular Diagnostic Technique

Common Femoral Artery

Understanding the anatomy of each vessel is key to avoiding potential complications.

Anatomically, the CFA begins as the external iliac artery emerges from under the inguinal ligament. One can note the origins of the superficial epigastric and circumflex iliac arterial branches at its most proximal aspect as it overlies the medial aspect of the femoral head. It courses for a short distance of 5–8 cm and then bifurcates into the superficial and deep femoral arteries. Within the femoral sheath, the CFA is immediately medial to the femoral nerve, and lateral to the CFV. The inguinal ligament is a useful landmark that can be identified using surface anatomy, but it is critical to recognize that this anatomy can be easily distorted by body habitus or prior surgical procedures. The use of fluoroscopy can assist in identifying the femoral head as well as bony landmarks of the superior iliac spine and pubic tubercle which may be less than easy to palpate. Identification of these bony landmarks are helpful in delineating the superior-most extent of the common femoral artery prior to its transition into the external iliac above the inguinal ligament ( Fig. 62.1 ). Using a skin marker may be useful to define inguinal ligament.

The CFA is an ideal choice for cannulation. It provides direct retrograde access to the aortoiliac system as well as most any arterial bed in the body. Its large caliber permits large devices introduction as well as safe room for most marketed percutaneous closure devices. Probably most importantly, the underlying femoral head allows easy compression and safe hemostasis even in the event of closure device failure. Most commonly, the CFA is accessed in retrograde fashion over the medial aspect of the femoral head. The location of the puncture is critical (see later). If puncture occurs too cephalad, either through or above the inguinal ligament, inadvertent puncture of the external iliac artery occurs, and a life-threatening retroperitoneal hematoma can result. Alternatively, if puncture is too distal, occurring in the superficial femoral artery (SFA), the risk of developing a pseudoaneurysm is quite high. SFA access can also result in an AV fistula from the profunda femoris artery or plaque dissection of the proximal SFA.

In certain circumstances, antegrade CFA access may be desired, more often for interventional rather than diagnostic purposes. Antegrade access may be chosen if the patient has a raised bifurcation in the setting of kissing iliac stents, causing difficulty with pushing a sheath over the aortic bifurcation. Antegrade access has the advantage of working in a single plane with excellent push ability for distal extremity procedures. Antegrade access into the CFA, however, can be more challenging than retrograde access. Needle puncture must still enter the CFA, but in antegrade access, the location is generally more on the proximal CFA to allow room to navigate wire and sheath into the SFA rather than the profunda artery. As such, this requires having a steep downward angle. In larger patients, this can be facilitated by retracting the pannus with tape.

Popliteal Artery

Anatomically, the SFA becomes the popliteal artery when it exits Hunter’s canal in the distal medial thigh. Fluoroscopically, this is often defined as the point when the femoral artery passes posterior to the medial aspect of the distal femur. The popliteal artery travels behind the knee and bifurcates into the anterior tibial artery and tibioperoneal trunk. The latter subsequently divides into the peroneal artery and posterior tibial artery (together, the so-called trifurcation). The popliteal artery is flanked on each side by the duplicated popliteal vein.

While almost never done for diagnostic purposes, retrograde access of the popliteal artery while in a prone position can be used to attempt to cross and re-enter an occlusion of the SFA. Ultrasound guidance is paramount to distinguish the artery from its accompanying popliteal veins. This method has been largely abandoned as compression in the fatty popliteal space is often ineffective and pedal access has become more attractive.

Infrageniculate Arteries

Pedal access has gained favor in some fields especially for recanalization of severe tibial disease when antegrade attempts fail. Ultrasound guidance and micropuncture needles are universally used. Once arterial access is confirmed, work is often completed without a sheath, using wires and catheters directly.

Anatomically, the anterior tibial artery courses anterolaterally from the below-knee popliteal and traverses deep within the anterior compartment of the leg. It becomes more superficial at the ankle and becomes the dorsalis pedis artery. The dorsalis pedis is the ideal pedal access point for its superficial location and ease of compression for hemostasis. The posterior tibial artery courses posteromedially from the tibioperoneal trunk and is located in the deep posterior compartment of the leg. It becomes palpable near the ankle. This relatively superficial location is also amenable to percutaneous access and can be compressed readily for hemostasis. The peroneal artery is rarely used for percutaneous access. Coursing straight inferiorly from the tibioperoneal trunk, it is difficult to reach in its deep location within the deep posterior compartment of the leg, between the tibia and fibula.

Iliac Artery

Because of inability to manually compress, as well as vital surrounding structures, percutaneous iliac artery access is contraindicated. If these arteries are needed for device deployment, open surgical approach is required. Often these are cases in which a conduit is sewn end-to-side to the iliac artery to allow introduction of large bore sheaths and devices. Alternatively, endo-conduits can be used within the iliac system to allow larger delivery systems of TEVAR and TAVR devices using femoral access (see Ch. 80 , Thoracic Aortic Aneurysms: Endovascular Treatment).

Axillary Artery

Percutaneous cannulation of the axillary artery has been historically done in the intramuscular groove between the triceps and coracobrachialis muscle with the upper arm in abduction and flexion. This location has until recently been abandoned due to difficulty with adequate compression against the humerus and risk of median nerve compartment syndrome. Since the caliber change as it becomes the brachial artery, most practitioners favor the latter if upper extremity access is desired. However, percutaneous access of the infraclavicular axillary artery more proximal has recently been described. Theoretically, this allows for larger caliber access similar to the CFA if multiple sheaths are required during complex endovascular interventions. This technique is still under review for two reasons. Compression is impossible in the event of closure device failure and quick surgical exposure (unlike femoral access) carries risk of brachial plexus injury.

Brachial Artery

The axillary artery becomes the brachial artery as it passes under the teres minor. It can be easily palpated over the olecranon process when the arm is supinated. Ultrasound-guided access is often used in conjunction with a micropuncture needle to facilitate safe entry into the vessel. One must take care to access the artery over the medial epicondyle to allow for compression and hemostasis. Furthermore, ultrasound guidance is recommended to ensure a single puncture attempt at the 12 o’clock position. Even a small hematoma can cause nerve compression with the tight brachial sheath. Most practitioners comfortably use 6F or 7F sheaths at this location. Brachial artery access is often used for coronary revascularization procedures, dialysis access, subclavian artery disease and some EVAR or complex EVAR procedures (see Ch. 75 , Aortoiliac Aneurysms: Endovascular Treatment). Many favor brachial access for mesenteric vessel cannulation due to the downward angle of their origins.

Radial Artery

The brachial artery bifurcates into the radial artery and ulnar arteries generally at the antecubital fossa. One should note that patients can have a higher bifurcation anywhere along the humerus. The radial artery has become the access of choice for most cardiologists and more recently for peripheral interventions. It is readily palpable in the distal extremity over the distal radius, and thus can be cannulated with ease, with or without using ultrasound guidance. Subsequent hemostasis is relatively straightforward through compression against the radius. Most patients are ulnar-dominant but all patients should undergo Allen’s testing or further imaging to ensure an intact palmar arch. If the patient is radial dominant and this is lost during intervention, the hand may become ischemic without collateral flow from the ulnar artery. The radial artery can accommodate sheaths between 4F and 6F, thus facilitating endovascular procedures that are using a 0.014” or 0.018” platform (see later).

Common Carotid Artery

Percutaneous common carotid artery (CCA) access is rarely performed for purely diagnostic purposes due to the risk of cerebral ischemia or embolization. Hemostasis is also a concern due to the inability to manually compress the carotid. Most practitioners will use CFA access with long guiding catheters or sheaths (see later) to achieve cannulation of the carotid artery. A hybrid technique is relied on for transcarotid artery revascularization (TCAR) when a small surgical incision is made to expose the CCA and direct puncture is then performed for antegrade sheath placement.

Common Femoral Vein

The CFV is commonly used for access when completing diagnostic procedures in the vena cava or its branches, such as the ovarian and internal iliac veins for pelvic congestion syndrome. The CFV is located medial to the CFA and can be compressed over the femoral head. Ultrasound guidance is often used for access to avoid injury to the CFA. This access readily allows catheterization of the contralateral extremity venous system, though navigating against the valves can require patience.

Popliteal Vein

To access the popliteal vein, the patient is generally positioned prone. Popliteal veins are paired, flanking the popliteal artery on each side, and either vein can be used for access. Ultrasound is used for guidance, which is particularly important when cannulating this vessel to diagnose and treat deep vein thrombosis of the extremity veins, as the access location itself may be thrombosed, rendering blood return via the needle meager or nonexistent. Ultrasound visualization of the puncture and guide wire passage can be extremely helpful in this situation. Accessing a thrombosed popliteal vein can require practice as the halting advancement of the guide wire can fool the practitioner into believing they are not intraluminal.

Saphenous Veins

The great and small saphenous veins are often cannulated for diagnostic and therapeutic purposes when treating patients for extremity deep vein thrombosis or for chronic venous insufficiency. Ultrasound guidance is typically necessary for access given their small size and distensibility. Most saphenous veins, both great and small, will typically accommodate at least a 6F sheath. The proximal small saphenous can be accessed to provide direct access to the popliteal vein to facilitate thrombolysis of femoral deep vein thrombosis (see Ch. 149 , Acute Lower Extremity Deep Venous Thrombosis: Surgical and Interventional Treatment).