Tibial Interventions for Peripheral Arterial Disease

Introduction

Endovascular treatment for tibial arterial disease has grown in popularity through technological advancement and improvement in techniques, allowing increased success in treating difficult lesions. With growing evidence for decreased morbidity and mortality, as well as equivalent limb salvage rates following endovascular therapy when compared with open bypass surgery, tibial percutaneous transluminal angioplasty (PTA) is now commonly used as first-line treatment for infrapopliteal atherosclerotic disease.

The Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC) guidelines provide recommendations agreed upon by multiple medical, surgical, and radiological societies in Europe and North America for the diagnosis and treatment of peripheral arterial disease. These guidelines are based on disease complexity and anatomic locality, offering treatment recommendations ranging from endovascular therapy for the least severe TASC A lesions to surgical revascularization for the most severe TASC D lesions. Initially, the TASC II classification systems only included aortoiliac and femoropopliteal segment treatment recommendations, but more recently, an updated infrapopliteal classification was created to include management of tibial lesions ( Fig. 35.1 ). However, in these updated classifications, groups such as the Society of Vascular Surgery were not represented. For many vascular specialists, endovascular treatment for TASC C or D lesions is considered because patients with chronic limb-threatening ischemia secondary to tibial disease tend to have multiple comorbidities and may benefit from a less morbid procedure rather than a tibial or pedal bypass. Proper prevention and management of complications will ensure technical success during endovascular treatment of tibial lesions when open bypass is not an option.

Arterial Access

Technique

The most common complication following endovascular interventions is related to arterial access. Using an appropriate technique reduces risks of arterial access complications. For lower extremity endovascular interventions, arterial entry is frequently obtained by contralateral retrograde common femoral access. This access orientation allows full evaluation of inflow aortoiliac vessels without potential visual interference from the sheath. Additionally, it provides the operator more working room, stability, and accessibility to wires and catheters along the patient’s contralateral leg. However, for more severely calcified infrapopliteal lesions, ipsilateral antegrade common femoral access may prove to be beneficial, given more direct pushability of wires and catheters. High or narrow aortoiliac bifurcations can lead to difficulty in advancing sheaths up and over the bifurcation, and antegrade access can be used to avoid this anatomy. Retrograde tibial access is a useful technique for lesions that cannot be crossed in antegrade fashion. Brachial access can be considered for treatment of infrapopliteal lesions when femoral access is contra-indicated; however, for taller patients, the working length of the wires and catheters may be insufficient for treatment of distal lesions.

Retrograde Common Femoral Artery Access

Routine use of ultrasound guidance for arterial entry will help reduce access-site complications. Although arterial access can be obtained with aid of direct palpation of the common femoral artery, practice with ultrasound will prove to be invaluable when more precise access is required. In our practice, we use a micropuncture technique for all arterial access, which involves the use of a 21-gauge needle and a short 0.018″ guidewire. We find this technique especially useful when obtaining access in calcified vessels by being able to place the needle tip accurately into a less diseased part of the artery. Short 21-guage micropuncture needles are also commercially available for use during retrograde tibial or pedal access. Needle entry into the vessel should be at a 45-degree angle, although a steeper angle may be required for more calcified vessels. Dilation of the skin and subcutaneous fat tract with a hemostat will aid successful deployment of the closure device at the end of the case. Please see Chapter 1 for further details regarding femoral access.

Retrograde femoral access and placement of a 4-French sheath is generally sufficient to advance a catheter into the contralateral external iliac artery for initial diagnostic imaging. However, in patients with severe peripheral arterial disease, multilevel disease burden, or poor cardiac output, injection of contrast at the external iliac level may not reach the tibial vessels for clear imaging. Therefore, the catheter will need to be advanced into the superficial femoral artery. For tibial interventions, the sheath will need to be upsized to a least a long 5-French sheath and placed into the superficial femoral artery (SFA) or popliteal artery to allow passage of tibial balloons and/or stents. Once the sheath is in place, it is always flushed and locked with heparinized saline. Alternatively, a continuous infusion of heparinized saline through the sheath may be utilized. Systemic heparinization for a diagnostic procedure is generally not necessary; however, if interventions are to be performed, a systemic bolus of heparin at 100 units/kg is given to prevent thrombosis. Activated clotting times (ACTs) are obtained every 20–30 minutes throughout the case, and heparin is redosed as needed to obtain an ACT level greater than 300 seconds. We recommend achieving these higher levels of ACT, given reported intraprocedural thromboembolism rates during tibial intervention as high as 4%.

Antegrade Common Femoral Artery Access

For ipsilateral antegrade access, precision in placing the arterial puncture over the femoral head is critical in preventing access site complications. Ultrasound visualization is important, not only for arterial entry but to direct the wire into the superficial femoral artery. Upsizing to a sheath should only be done once there is confirmation of SFA selection with the wire. Direct SFA access can be performed in certain situations where common femoral artery access is contra-indicated and the SFA is sufficient in diameter. In patients with a large obstructing pannus, it is helpful to reflect and to secure the pannus cranially with tape prior to prepping, draping, and attempting access.

Part of the difficulty of ipsilateral antegrade access is the directionality of wires toward the patient’s head, resulting in workspace limitations. Using a longer sheath and arching the extracorporeal portion of the sheath to the contralateral side to direct the wires along the contralateral leg is a helpful technique. Securing the sheath to the patient or the drapes will prevent accidental sheath dislodgement. If a sheath is dislodged during a procedure, it is important to replace and reinsert the inner sheath dilator before advancing the sheath into the artery to avoid damaging the tip of the sheath and injuring the artery. Upon completion of the procedure following either retrograde or antegrade common femoral access, manual pressure is usually sufficient to obtain hemostasis, given the small sheath size required for tibial interventions. Following manual compression and hemostasis, we require patients to lie flat for 1 hour per sheath size used.

Retrograde Tibiopedal Access

Retrograde percutaneous tibiopedal access has become an important tool for treating tibial lesions that cannot be crossed from an antegrade approach. Obtaining tibiopedal access can be challenging, given the small size and extensive calcification of these vessels. Initial antegrade run-off angiography will identify the location of distal reconstitution, which will be the target for retrograde access. This arterial entry point is then identified under ultrasound visualization and accessed using a short micropuncture 21-gauge needle ( Fig. 35.2A,B ). If access fails following multiple attempts, the artery may go into vasospasm. Intra-arterial injection of nitroglycerin through the antegrade sheath and warming the leg can help resolve the vasospasm. Nitroglycerin can be administered intra-arterially through the sheath or catheter in 100–200 µg increments. Hypotension is rarely seen when administering nitroglycerin directly to the infrapopliteal arteries.

Alternatively, retrograde access can be obtained under direct fluoroscopy using calcification as a roadmap or handheld contrast injections from the proximal catheter. However, this exposes the interventionalist to higher doses of radiation. Occasionally, patients are unable to remain comfortable and still for these procedures while under monitored sedation, and in those cases, general anesthesia may be useful. Following successful retrograde tibiopedal access with the micropuncture needle, the inner cannula of the micropuncture sheath is used as the tibial sheath ( Fig. 35.2C ). Alternatively, commercially available microsheaths can be used. However, we prefer the inner dilator alone to minimize the profile of the sheath in the tibial vessel. Following completion of the case and removal of all devices, hemostasis can be obtained via direct pressure over the tibial access point. Alternatively, inflation of a blood pressure cuff can be used for deeper accessed tibial vessels (e.g., peroneal) to achieve hemostasis. Closure devices should be avoided in these small vessels, given device-vessel size discrepancy and the risk of vessel narrowing and thrombosis.