Peripheral arterial disease (PAD) comprises a host of noncoronary arterial syndromes due to various pathophysiological mechanisms resulting in stenosis or aneurysms in various vascular beds. Atherosclerosis (AS) remains by far the most common cause of this disease process. According to the recently released ACC/AHA guidelines for the management of patients with PAD, it is a major cause of decrement of functional capacity, quality of life, limb amputation, and increased risk of death.¹

Millions of people worldwide are afflicted with this syndrome.^2,3 While awareness for coronary artery disease (CAD) has significantly increased in the last decade, the awareness, diagnosis, and treatment of PAD remain much underappreciated. With improvement in catheter-based and imaging technology, it was only natural that all specialties involved in the management of vascular disease would involve endovascular therapy of this potentially disabling and lethal disorder.^4,5,6

Excellent reviews on PAD are already available in the literature. The ACC/AHA guidelines, Trans Atlantic Society Conference (TASC) Working Group document,⁷ the ACC COCATS-2 Paper,⁸ provide the basic fundamental material for a physician interested in the management of patients suffering from PAD. Based on literature review and our own experience at the Washington Hospital Center, Washington, DC, and University of Louisville, Louisville, KY, we have tried to focus in this chapter on the general principles of performing invasive peripheral angiography. We have also briefly described noninvasive imaging modalities of computed tomographic angiography (CTA), magnetic resonance angiography (MRA), and carbon dioxide (CO₂) angiography as their utility relates to each vascular bed. The full details of these other modalities are, however, out of the scope of this chapter. We hope that this chapter will provide the basic understanding in catheter angiography to an operator interested in treating patients with PAD.

Training Requirements

There are considerable differences of opinion that exist among various specialties regarding the optimal training required before certifying operators to safely perform peripheral vascular procedures.^{9,10,11,12,13,14,15,16} Specialties including interventional cardiology, interventional radiology, vascular surgery, interventional neuroradiology, interventional nephrology, and interventional neurosurgery all possess basic and unique knowledge that positions them to advance their skills into peripheral angiography and interventions. The ACC COCATS-2 (Tables 20-1 and 20-2) provides guidelines for a cardiovascular trainee who wishes to be certified in the performance of such procedures.

A minimum of 12 months of training is required. Completion of 100 diagnostic angiograms and 50 peripheral vascular interventions has been recommended for unrestricted certification. Fifty percent of such procedures should be performed as “primary operator” under the guidance of a mentor who is certified in peripheral vascular interventions. Prior to the performance of invasive procedures, this physician should be knowledgeable in vascular medicine and noninvasive modalities in the diagnosis of peripheral vascular disorders. Before signing off the certificate, the mentor should require the trainee to have exposure in the angiography of various vascular beds. This should also include cases of vascular thromboses and their treatment. Carotid and vertebral artery angiography is excluded from most general guidelines and added skills are required in this vascular territory. The ACC/ACP/SCAI/SVMB/SVS Clinical Competent Statement outlines these requirements (Tables 20-3 and 20-4).

Restricted certificates can be awarded to physicians who achieve satisfactory skills in only certain vascular territories. Maintenance of certification is also required by continuous medical education and performance of 25 peripheral vascular interventions per year. For full details, the reader may refer consensus conference guidelines.¹⁷

Noninvasive imaging is improving at a rapid pace and is replacing routine catheter angiography in many cases.

Magnetic Resonance Angiography

According to the ACC/AHA guidelines, MRA with gadolinium contrast is now a Class I indication (conditions for which there is evidence for and/or general agreement that a given procedure or treatment is beneficial, useful, and effective) and level of evidence A (data derived from multiple randomized trials or meta-analysis) to diagnose the anatomic location and degree of stenosis in the lower extremity PAD; and to select patients who are candidates for endovascular or surgical revascularization. MRA has Type IIb indication (conditions for which there is conflicting evidence and/or divergence of opinion about the usefulness/efficacy of a procedure or treatment. Weight of evidence/opinion is in favor of usefulness/efficacy) and level of evidence B (data derived from a single randomized trial or nonrandomized trials) in patients with PAD to select surgical sites for surgical bypass and for postsurgical and postendovascular revascularization surveillance. Gadolinium is less nephrotoxic and there is no exposure to ionizing radiation. Currently utilized techniques of MRA include time of flight (TOF), three-dimensional imaging, contrast enhancement with gadolinium subtraction, cardiac gating and bolus chase.¹⁸ With the contrast-enhanced MRA (CE MRA), the sensitivity is 90% and specificity 97% in lower extremities PAD as compared to digital subtraction angiography (DSA).^19,20,21 Runoff vessels may, in fact, be better visualized with MRA than DSA.^22,23 In the patients diagnosed with critical limb ischemia (CLI), with intra-operative angiography as the standard, MRA had comparable accuracy to standard catheter angiography. Sensitivity and specificity for patent vessels was 81% and 85%, respectively. For the identification of segments suitable for bypass grafting, the sensitivity of contrast angiography was less than MRA (77% vs. 82%), but the specificity was better (92% vs. 84%).²⁴ A meta-analysis of MRA compared to catheter angiography for stenoses >50% showed that the sensitivity and specificity were 90% to 100%, especially when gadolinium was used.²⁵ Recent studies also show an agreement of 91% to 97% between MRA and catheter angiography.²⁶

MRA, however, tends to overestimate the degree of stenosis and occlusions. It might also be inaccurate in assessing lesions with stents. Another limitation is in patients who have been implanted with automatic defibrillators, permanent pacemakers or who have intracranial coils or clips.^27,28 In these patients, MRA is generally contraindicated. Gadolinium is generally considered nonnephrotoxic, but one study reported nephrotoxicity in patients with baseline renal dysfunction.²⁹ A significant number of patients are also severely claustrophobic during imaging and require alternative testing.

Computed Tomographic Angiography

CTA is considered by ACC-AHA guideline committee to merit a Type IIb indication (usefulness/efficacy is less well established by evidence/opinion) and level of evidence B for diagnosing the anatomic location and presence of stenoses in patients with lower extremity PAD. It is considered as a substitute for MRA in patients who have contraindication to MRA.^{30,31,32,33,34}

This technique was first started in 1992. Image acquisition is very rapid. Images can be rotated in three dimensions, thus bringing into view eccentric lesions that might be missed by two-dimensional catheter angiography. Older scanners had a single detector that acquired one cross-sectional image at a time and was very time-consuming. It also required more contrast load and there was overheating of the X-ray tube. The currently available multidetector CT (MDCT) scanners can acquire 64 slices simultaneously.^{34,35,36,37,38,39} Abdominal aorta and the entire lower extremity can be imaged in less than 1 minute.⁴⁰ One hundred to one hundred eighty milliliters of iodinated contrast is injected at 1 to 3 mL per minute via a peripheral venous line. The radiation exposure is typically one-quarter of that in catheter angiography.

With the single detector scanners, the sensitivity for occlusions was 94% and specificity was 100%. For stenoses greater than 75%, the sensitivity and specificity dropped significantly to 36% and 58%, respectively, when maximum intensity projection was used and improved to 73% to 88% when each slice was individually analyzed. With the MDCT, the sensitivity for stenoses greater than 50% was 89% to 100% and the specificity was 92% to 100%.

CTA is useful in selecting patients who are candidates for endovascular or surgical revascularization. It also provides useful information about associated soft tissue structures that may affect decision making in the optimal endovascular treatment of PAD, e.g., vascular aneurysms. In one study, it showed that popliteal artery stenosis and occlusions occurred because of aneurysms, cystic adventitial disease, or entrapment.⁴¹ Other advantages are patient comfort, and compared to DSA, it is noninvasive, less expensive, delivers less radiation (approximately one-fourth) and has better contrast resolution.⁴²

The major limitation of CTA is the risk of contrast-induced nephropathy (CIN). Other drawbacks include lack of accuracy with single detector scanners, lower spatial resolution than DSA, venous filling obscuring arterial imaging, decreased accuracy in calcified vessels, and asymmetrical opacification of legs. The accuracy and effectiveness of CTA is not as well delineated as that of an MRA. Treatment plans based on CTA have not been compared with those of contrast angiography in lower extremity PAD.

Carbon Dioxide Angiography

CO₂ angiography is not available in most centers and generally reserved for patients with history of contrast allergy or renal dysfunction with creatinine clearance less than 20 mL per minute. The use is generally limited to arteries below the diaphragm to minimize the risk of cerebral embolism. DSA equipment is required for CO₂ angiography.^{43,44,45,46,47,48,49,50}

In spite of tremendous improvements in noninvasive imaging, catheter-based invasive iodine contrast catheter angiography remains the gold standard for the diagnosis of PAD in patients considered for endovascular intervention. It is the most widely available modality for the imaging of the vasculature. It is the only universally accepted technology for guiding percutaneous peripheral vascular interventions. Millions of angiographic procedures have been performed worldwide since William Forssman in 1929 passed a catheter from his own arm vein into his right atrium.⁵¹ In the early period, direct punctures of the vessels of interest were performed.⁵² This technique has essentially been abandoned and replaced by percutaneous needle access. Safe and good quality angiography requires adequate equipment, well-trained team of staff, and strict adherence to well-established principles.

Catheter angiography has a Class I ACC/AHA indication for delineating the anatomy in patients who require revascularization. Modern technology has permitted the use of smaller diameter sheaths and catheters, less toxic contrast agents, better imaging equipment in angiographic suites requiring less contrast load, thus decreasing the risks to the patient for adverse effects. Invasive angiography procedures, however, are still associated with rare but potentially devastating complications. The risk of severe contrast induced reaction is 0.1%.^53,54 There is significant risk of CIN in patients with baseline renal dysfunction, patients with diabetes mellitus, those with low cardiac output states or those who are dehydrated. Any combination of these is more adverse than an individual risk factor.

Informed consents should be obtained prior to the procedure from all patients after fully explaining all the risks, benefits, and alternatives. History of contrast-related allergic reactions should be documented and appropriate pretreatment should be administered. Decisions regarding revascularization should be made with complete anatomic assessment of the affected arterial territory including imaging of the occlusive lesion as well as of the inflow and outflow vessels. Noninvasive imaging techniques should be combined with vascular imaging for the information. DSA should be used to eliminate dense background tissues. Selective and superselective catheter placement should be done for better enhancement of vasculature and to reduce the contrast load and radiation exposure. Imaging should be done in multiple angulations to uncover vessel overlap, and transstenotic pressure gradients be measured in ambiguous lesions. In patients with renal dysfunction, appropriate hydration should be given prior to the procedure. Patients should be followed up within 2 weeks of the procedure to assess their renal function, the access site, and to make sure that they have not suffered adverse effects like atheroembolism.

Radiological Equipment

Peripheral angiography frequently requires imaging of large areas, which in the absence of a large field of view, will require multiple injections and significant contrast load. A 14-inches (36-cm) image intensifier is recommended (Figure 20-1). Cineangiography at 15 to 30 frames per second (FPS) is excellent for imaging of the moving beating heart.⁵⁵ Imaging of static structures with radioopaque bones in the background, e.g., blood vessels, especially the smaller branches will be suboptimal with this technique. Therefore, the technique of DSA should be utilized for peripheral angiography. In this technique, the patient is required to stay motionless during images; otherwise the image will be distorted. In carotid angiography, the patient should also be instructed not to swallow to prevent motion. In modern angiographic suites, ability to acquire DSA images has cut down on the contrast and radiation exposure. In DSA, a precontrast “mask” image is first obtained. Following contrast injection, subtraction of this image allows enhanced filling of the vasculature with masking of nonvascular structures like bones, air, and calcium. Gadolinium or CO₂ angiography should be done in laboratories equipped with DSA; otherwise, the image quality is likely to be poor. “Road mapping,” also called “trace subtract fluoroscopy,” is usually available in catheter laboratories equipped with DSA capability. This is a very useful technique during interventional procedures. This can be conceptualized as fluoroscopy without the radioopaque background. A small amount of contrast is first injected to fill the vessel and the image is stored in memory as a mask. When the catheter is advanced under normal fluoroscopy, this mask is subtracted, thus allowing visualization of both the moving catheter and the vessel. The image in road mapping will appear white in contrast to DSA, where it will be black. Additional software, enabling quantitative angiography to measure lesion length and diameter should also be ideally available in current angiographic suites.

Examination Console

Highest kilovoltage peak (KVP) is required for cerebral and abdominal angiography, lowest for the extremities, and intermediate for the thorax. Frame rate is generally 2 to 3 FPS for arterial imaging. It is decreased for venous imaging due to long cine runs. Frame rate is increased for cases requiring gadolinium contrast. Newer laboratories will typically have the settings on the console that can be adjusted to optimize adequate imaging of each vascular bed.

In the imaging of the legs 12- to 15-inch image intensifier is required. A longer table is also desirable. Where these are not available, the patient can be positioned in reverse with feet facing the head end of the table. Multiple injections maybe required in the legs to image all the arteries. Depending on the operator and the staff experience, either a “stepped mode” method, which requires contrast bolus at each imaging site, or an “interactive” method where a single bolus of contrast is given in the abdominal aorta and the table is automatically set to “chase” down the bolus all the way to the feet are utilized for angiography. In our own experience, the stepped mode technique produces better images with the flexibility of changing the amount of contrast and angles during imaging. It may however require slightly larger contrast load and exposes operators to more radiation.

In the “interactive” method, after the bolus is given, a DSA run of both the lower extremities is obtained followed by a “dry run” used for subtraction. This technique is sometimes limited by unequal visualization of both legs in larger patients or in the patients who have flow-limiting lesions in a segment of the vessel causing delayed filling distally. Patients may also be unable to lie motionless or hold their breath for the entire duration of the time required for imaging of all the segments. If free movement of the table is not confirmed prior to the automatic runs, there is a danger of pulling out of the imaging catheter and the sheath. We recommend suturing the sheath if using this method.

Radiation Exposure

Peripheral angiography procedures are typically more time consuming than coronary procedures. Frustration can easily set in during a difficult case especially if the staff is not completely familiar with the equipment and trouble shooting of the modalities commonly used, e.g., DSA, road mapping, bolus chase etc. Also, many laboratories have trainee fellows and less experienced operators trying to learn this increasingly popular skill. Basic principles to prevent radiation exposure can thus be overlooked.

Maximizing distance from the X-ray source is the best way to reduce exposure. Most procedures by the right-handed individuals are done from the right side of the table. Right anterior oblique (RAO) angulation moves the X-ray tube away from the operators, thus exposing them to less radiation than left anterior oblique (LAO) angles. Protective lead shields, good-quality lightweight aprons, thyroid collars, and leaded eyeglasses should be used as a habit. Use of DSA and road mapping will further cut down on flourotime. Radiation badges should monitor radiation exposure of each operator and staff.

Intravenous Contrast Agents

All current contrast agents are iodine-based. The high atomic number and chemical versatility of iodine makes it ideal for vessel opacification.⁵⁶ They are classified as ionic or nonionic and further differentiated into high-osmolar, iso-osmolar, and low-osmolar based on their osmolality. Low- and iso-osmolar agents cause fewer side effects, e.g., hypotension, bradycardia, angina, nausea, and vomiting. They also cause less heat sensation and are better tolerated in peripheral angiography. The nonionic agents cause less allergic side-effects and may also be less nephrotoxic. The nonionic, hypo-osmolar and iso-osmolar agents are more expensive.^57,58,59,60 Some patients maybe intolerant to pain and heat sensation even with the iso-osmolar agents. A 50:50 mixture with saline using DSA imaging can be used in such cases. Many agents are commercially available in the market based on their ratio of iodine to ions and concentration of sodium (that determines their osmolality).

High-osmolar ionic ratio 1.5 agents contain three atoms of iodine for every two ions, e.g., Renografin (Bracco), Hypaque (Nycomed), and Angiovist (Berlex). Their sodium concentration is roughly equal to that of blood, making their osmolality very high (>1500 mosm/kg). They cause significant pain and are generally not tolerated well by patients undergoing peripheral angiography.

Low-osmolar ionic ratio-3 agents have three atoms of iodine for every one ion and are low osmolality agents. Their osmolality is roughly twice that of blood, e.g., Ioxaglate (Hexabrix, Mallinckrodt).

Low-osmolar nonionic ratio-3 agents are water-soluble and do not have any ions, e.g., Iopamidol (Isovue, Bracco), Iohexol (Omnipaque, Nycomed), Ioversol (optiray, Mallinckrodt). Their osmolality is also twice that of blood and cause burning in many patients.

Iso-osmolar nonionic ratio-6 agents have osmolality equal to that of blood (290 mosm/kg). They are very well tolerated by patients. Most commonly used is Iodixinol (Visipaque, Nycomed). It has fewer incidences of allergic reactions than Ioxaglate and has shown no major increase in adverse coronary events like intravascular thrombosis, vessel closure, or perioperative myocardial infarction.⁶¹ There is also some data suggesting less nephrotoxicity with them.

In all patients with renal dysfunction, intravenous hydration with normal saline at 1 mL/kg/h along with N-acetylcysteine (mucomyst) 600 mg orally twice a day should ideally be started 12 to 24 hours prior to the procedure. Gadolinium contrast or CO₂ angiography is another option in such patients.

Diagnostic Catheters and Guide Wires

Vascular access is commonly obtained with an 18-gauge needle that will accommodate most 0.038 inch or smaller wires. A smaller 21-gauge needle with a 0.018-inch wire is available in “micropuncture kit” (Cook, Bloomington, IN) that can be used for difficult femoral, brachial, radial, or antegrade femoral approaches (Figure 20-2). For a nonpalpable pulse Doppler, integrated needle (smart needle) can be used. Wires are available in 0.012 to 0.052 inch in diameter. Most commonly used are wires of 0.035 and 0.038 inch. In a standard guide wire, a stainless steel coil surrounds a tapered inner core. A central safety wire filament is incorporated to prevent separation in case of fracture. Typically they are 100 to 120 cm in length but can also be 260 to 300 cm. Wires are available when wire position needs to be maintained for catheter exchanges. Long wires are frequently required in peripheral angiography, more so than in coronary angiography and their use is encouraged when in doubt.

The tip of the wires can be straight, angled, or J-shaped. Some wires have the capability of increasing their floppy tip by having a movable inner core. Varying degrees of shaft stiffness, e.g., extra support, to provide a strong rail to advance catheters in tortuous anatomy versus extremely slick hydrophilic with low friction for complex anatomy have made peripheral vascular angiography and interventions a viable and many times a preferred treatment of PAD.

Every angiographic suite should have an inventory of such wires. The 0.035-inch wires used in our laboratory are standard J-shaped, Wholey, Straight and Angled Glide, Amplatz Super Stiff, and Supracore. Among the 0.018-inch wires inventory are the Steel Core and V18 Control. In addition to 0.014-inch coronary wires, we frequently use Sparta Core wire in renal and other peripheral vascular interventions. Glide wire (Terumo wire) is very useful in tracking most vessels but carries the risks of vessel dissection and perforation. It should not be used to traverse needles because of the potential of shearing.

Numerous catheters are available (Figures 20-3, 20-4 and 20-5) and every operator should develop his own skill and “feel” of catheters he uses in peripheral angiography. An “ideal catheter” should be able to sustain high-pressure injections, to track well, be nonthrombogenic, have good memory, and should torque well.⁶² Catheters are made of polyurethane, polyethylene, Teflon or nylon. They have a wire braid in the wall to impart torquibility and strength. They are available in different diameters and lengths. They can have an end hole, side holes, or both end and side holes. When using the femoral approach, short-length catheters (60–80 cm) are adequate for angiography of the structures below the diaphragm, whereas long catheters (100–120 cm) are needed for carotid artery, subclavian artery, or arm angiography. Five- to six-French catherter (1-F catheter = 0.333 mm) diameter catheters are most commonly used. Three- to four-French catheters are used for smaller vessels. Side-hole catheters are safe and allow large volume of contrast at a rapid rate with power injectors, e.g. pigtail, Omniflush, Grollman. They are commonly used for angiography of ascending aorta, aortic arch, and abdominal aorta. End-hole catheters are very useful in selective angiography using manual hand injections. For DSA, 5-F catheters are sufficient.

Omniflush catheter can be advanced over the wire beyond the aortic bifurcation and then pulled back to engage the contralateral common iliac artery for selective angiography of the leg. For type-1 aortic arch, a 5 F JR4 will be adequate for carotid, vertebral, subclavian artery angiography, and for nonangulated renal arteries. Simmons, Vitek, SOS, and Amplatz catheters are very useful in certain situations but require added skills and careful manipulation. Heparin should be used with the use of these latter catheters. Simple curved catheters, e.g., Berenstein, Cobra, and Headhunter, are also useful in angulated renal arteries and vertebrals.

Vascular Access

Meticulous technique to achieve vascular access is essential for a successful angiographic procedure. In patients with PAD, the success or failure of a procedure will significantly depend on the correct choice of access site. Every effort should be made to learn the vascular anatomy and direction of blood flow if the patient had previous bypass graft. Prior noninvasive studies like MRA, CTA, and Duplex ultrasonography (US) should be reviewed prior to the angiography. Peripheral bypass grafts in general should not be punctured for 6 to 12 months after surgery.

Most common vascular sites are common femoral artery (CFA) and brachial artery (BA).^63,64 Fluoroscopy should be routinely used to identify bony landmarks to avoid puncturing the artery too low or too high.

Femoral Approach

CFA is ideally suited because of its large caliber that can accommodate up to 14-F sheaths percutaneously and its central location, enabling access to all vascular territories. When compared to the arm approach, there is less radiation exposure but more incidence of bleeding and delayed ambulation. Both retrograde (toward the abdomen) and antegrade (toward the feet) CFA punctures are routinely done. For the antegrade approach, micropuncture technique using 21-gauge needle with 0.018-inch wire is recommended. It should always be done under fluoroscopy and should not be done in very obese patients. It limits arteriography to the ipsilateral leg, but provides a better platform for interventions if needed. Patients are typically placed in reverse with the feet facing the head-end of the table, allowing maximum mobility of the image intensifier around the limbs. The skin puncture is made at the top of the femoral head. A less acute, less than 45-degree angle is usually required for smooth insertion of the sheath and catheters. Long tapered introducer-sheath instruments are sometimes needed. A short 4- to 5-F sheath should be introduced first and a cine angiogram performed to confirm access in the CFA, and wire position in the superficial femoral artery (SFA) before inserting the larger and longer sheaths and initiation of anticoagulation⁶⁵ (Figure 20-6). An ipsilateral 30 to 50 degrees angulation will open up the superficial and deep femoral artery (DFA) bifurcation. Anticoagulation can be reversed at the end of the procedure for early removal of sheath and to decrease the incidence of bleeding.

Brachial and Radial Approach

For radial artery (RA) and 5- to 6-F sheaths and for brachial artery 5- to 7-F sheaths can be used. The biggest advantage with these approaches is less bleeding and early ambulation.^66,67,68 There are however more ischemic complications.⁶⁹ These approaches require crossing the great vessels of aorta and great care should be exercised to avoid causing embolic strokes.

For BA approach, the arm is abducted and the puncture is made at the site of maximum pulsation. Micropuncture technique is recommended. When using this approach, one should be aware of the need for longer length catheters if angiography and intervention of the lower extremities is anticipated. Left brachial approach has approximately 100 mm greater reach than the right brachial approach. Wholey wire, glide wire, and other soft wires should be used with these approaches to minimize trauma and spasm of the vessels.

For RA approach,⁷⁰ more skill is required. RA is superficial and lies against the bone. It has no major veins or nerves in the vicinity. Its smaller size, however, limits the use of some devices and larger stents. Hydrophilic sheaths and guiding catheters of upto 6- to 7-F are now available and can be used with this approach. They can accommodate most current balloons and stents. There is approximately a 3% incidence of RA occlusion postprocedure. Allen’s test⁷¹ should be performed prior to cannulating RA to confirm the ulnar artery patency (Figure 20-7). There is, however, some controversy regarding the absolute value of Allen’s test. The success rate of this approach is 95%.⁷² The wrist is extended and the arm abducted in supine position. Using micropuncture technique, puncture is made 1 to 2 cm proximal to the wrist crease. After sheath insertion, the arm is brought back in the adducted neutral position. Right arm is preferred to preserve left RA for future bypass surgery if needed. Minimal local anesthesia is administered. Five F long hydrophilic sheath is a good choice. Heparin 2500 to 5000 units should be given directly in the sheath. Radial arteries are very prone to spasm and vasodilators should be used. Nitroglycerin 100 to 200 mg and Verapamil 1 to 2 mg is directly given through the sheath. A short cineangiogram should be performed to look for any anomalous arteries. One should look for radial recurrent artery. The sheath should be removed immediately after the procedure. Activated clotting time (ACT) check is not necessary. Compression straps, e.g., Hemoband (Hemoband Corp., Portland, OR) are placed directly over the puncture site. Pressure is maintained for approximately 90 minutes for diagnostic and 180 minutes for interventional procedures. Access site complications are very uncommon.

Other Vascular Access Sites

PA is uncommonly accessed. The patient has to lie prone. Puncture is performed under fluoroscopy and micropuncture technique is recommended. Axillary approach is more popular among interventional radiologists. Left axillary artery is preferred. The patient needs very close monitoring for bleeding after axillary artery puncture because even a medium-sized hematoma can cause nerve compression. BA cut down is very uncommon now. It is used in less than 10% of cases and should be performed only by experienced operators. Lumbar aortic punctures are again sometimes used by radiologists in patients who have extensive PAD.⁷³ Patient is placed prone. This site is only used as a last resort because in case of bleeding complications direct pressure cannot be applied and patient will likely require open surgical repair of the bleeding vessel.

Local Vascular Complications

Society for Cardiac Angiography and Interventions (SCAI) has reported an incidence of 0.5% to 0.6% local vascular complications. These complications comprise vessel thrombosis, dissection (Figure 20-8), bleeding, which can be free hemorrhage, retroperitoneal bleeding, or access site hematoma, arteriovenous fistula (Figure 20-9), distal embolization, or false aneurysm (pseudo aneurysm).

The operator should be well versed in the diagnosis and management of these complications. Adequate specialty care should be readily available at the facility where such procedures are performed.

Thoracic Aorta and Aortic Arch Angiography

Noninvasive modalities like MRA and three-dimensional CTA should be performed if available prior to invasive imaging. Angiography provides 2D imaging and may underestimate the tortuosity of various vessels (Figure 20-10). CTA and MRA will also provide information about the type of aortic arch, and anomalous origin of any vessel from the arch (Figure 20-11).

Thoracic Aorta

Commonly approached via right CFA utilizing 4- to 6-F sheath and diagnostic catheters. Pigtail or tennis racquet catheter is advanced over a soft J-tip guidewire under fluoroscopy. In cases of coarctation of the aorta, anteroposterior and lateral views are obtained with the contrast injected proximal to the coarctation. For cases of patent ductus arteriosus, selective aortic angiography is very sensitive in demonstrating small shunts and supercedes the sensitivity of right heart catheterization with stepwise oximetry. In cases of thoracic aortic aneurysms (TAA), MRA and CTA are again very useful initial tools (Figure 20-12), but catheter angiography is still considered essential to delineate the aneurysm and its relationship to the branches in the chest and abdomen. If endovascular thoracic aneurysm repair (ETAR) or open surgical repair is planned, then coronary, brachiocephalic, visceral, and renal arteriography should also be performed. For the diagnosis of thoracic aneurysms, angiography is performed in the ascending thoracic aorta above the aortic valve using 30 to 40 mL of iodinated contrast at 15 to 20 mL/s using power injection. TAA is less common than abdominal aortic aneurysm (AAA) but the incidence is increasing as the median age of the population is also increasing. It also has a higher incidence of rupture than AAA. Untreated, the mortality is greater than 70% within 5 years of diagnosis.⁷⁴ Open surgical repair has a mortality of 10% to 30%, spinal cord injury 5% to 15%, respiratory failure 25% to 45%, myocardial infarction 7% to 20%, and renal dysfunction 8% to 30%.⁷⁵ Chronic obstructive pulmonary disease (COPD) and renal failure are strong predictors of rupture. In one series,⁷⁶ the rupture rate was high for aneurysms greater than 6 cm. In another series, no rupture was reported in aneurysms less than 5 cm. Mean size for rupture was 5.8 cm. With ETAR, the mortality and the morbidity has been reported to be much less.⁷⁷

In cases of thoracic aortic dissection, angiography has a sensitivity of 80% and specificity of 95%. Noninvasive modalities like CTA, MRA, and transesophageal echocardiography have taken over as the initial diagnostic tools; however, cardiothoracic surgeons will still require an angiogram for additional information about coronary and branch vessel involvement and the competence of the aortic valve prior to aortic repair. A pigtail or tennis racquet catheter is advanced over a soft wire typically via the right CFA approach. Most of the aortic tears are at the greater (outer) curve and to avoid entry into the false lumen, the catheter is used to direct the wire toward the inner curve. Frequent contrast injections should be utilized to check the catheter position. Entry into the false lumen is not uncommon and if that occurs, the catheter should be gently retracted and advanced into the true lumen.