Peripheral Vascular Intervention

14 Peripheral Vascular Intervention



Peripheral arterial disease (PAD) refers to stenotic, occlusive, and aneurysmal diseases of the aorta and branch arteries that include the lower extremity, upper extremity, renal, mesenteric, and carotid arterial beds. PAD is a common manifestation of atherosclerosis, and its prevalence increases with age and concurrent cardiovascular risk factors such as diabetes and tobacco use. As with coronary artery disease (CAD), PAD has a natural history, progression pattern, and susceptibility for developing vulnerable and complex plaques with a strong positive correlation to cardiovascular events and mortality.


Cardiovascular disease is the major cause of death in patients with intermittent claudication. Patients with newly diagnosed PAD are six times more likely to die within the next 10 years when compared with patients without PAD.


In 2006 the American College of Cardiology and American Heart Association (ACC/AHA) developed guidelines to aid in the diagnosis and management of patients with PAD. These guidelines suggest that individuals with the following characteristics would be at risk from PAD:




Patient Selection for Peripheral Endovascular Intervention


When considering patients for peripheral endovascular intervention (PVI), an accurate history and physical exam are most important. Initial risk factor assessment and screening tests for cardiovascular disease, should be obtained. Patients should be medically optimized. The review of symptoms and family history is an essential component of the vascular history. The key component to the diagnosis of PAD is the presence of symptoms. However, <20% of PAD patients report the typical symptoms of intermittent claudication. Many patients present with atypical symptoms. These include:



The patient history should include questions that try to distinguish PAD from diseases that have a non-PAD etiology (Table 14-1).


Table 14-1 Questions Used to Distinguish PAD Symptoms From Non-PAD


















Pain and location Do you have pain or discomfort?
Where is the discomfort?
Consistency Is the pain the same every time?
Severity How much can you do before the pain starts?
Have your activities changed because of the pain?
Character and quality What does the discomfort feel like?
Can you describe it?
Exacerbation What makes the pain worse?
What relieves the pain?

PAD, peripheral arterial disease.


Intermittent claudication is the most classic manifestation of PAD. In 1962 epidemiologist Geoffrey Rose designed a questionnaire to assess the incidence and prevalence of intermittent claudication in large epidemiologic studies. The sensitivity of the Rose claudication questionnaire approaches approximately 10% to 30%; however, similar questions (and modifications to the Rose questionnaire) are still very helpful in diagnosing intermittent claudication (Table 14-2).


Table 14-2 Rose Questionnaire: Symptoms of Classic Intermittent Claudication





Calf pain caused by exertion that:

True vascular claudication must be distinguished from “pseudoclaudication” caused by severe venous obstructive disease, chronic compartment syndrome, lumbar disease and spinal stenosis, osteoarthritis, and inflammatory muscle diseases. The characteristic features of pseudoclaudication that distinguish it from claudication are summarized in Table 14-3.


Table 14-3 Distinguishing Characteristics Between Claudication and Pseudoclaudication



































  Claudication Pseudoclaudication
Characteristic of discomfort Cramping, tightness, aching, fatigue Same as claudication plus tingling, burning, numbness
Location of discomfort Buttock, hip, thigh, calf, foot Same as claudication
Induced by exercise Yes Variable
Reproducible with distance walked Consistent Variable
Occurs with standing No Yes
Actions that provide relief Standing Sitting, changing position
Time until relief <5 min <30 min

Symptoms of intermittent claudication classically start distally within a muscle group (below the stenosis) and then ascend with continued activity. Rest pain that occurs with leg elevation and is relieved paradoxically by walking may suggest severe PAD (as the effects of gravity increase arterial perfusion of muscle groups). Critical PAD may present as tissue ulceration and gangrene. The ACC/AHA guidelines suggest that individuals with PAD present in clinical practice with distinct syndromes (Table 14-4).


Table 14-4 Distinct syndromes of PAD















Individuals with peripheral arterial disease (PAD) present in clinical practice with a variety of distinct syndromes:
Asymptomatic: Without obvious symptomatic complaint (but usually with a functional impairment)
Classic claudication: Lower extremity symptoms confined to the muscles with a consistent (reproducible) onset with exercise and relief with rest
“Atypical” leg pain: Lower extremity discomfort that is exertional but that does not consistently resolve with rest, consistently limit exercise at a reproducible distance, or meet all Rose questionnaire criteria
Critical limb ischemia: Ischemic rest pain, nonhealing wound, or gangrene
Acute limb ischemia: The five “P”s, defined by the clinical symptoms and signs that suggest potential limb jeopardy: pain, pulselessness, pallor, paresthesias, paralysis (and polar, as a sixth “P”)

The physical exam defines the location, severity, and etiology of PAD and its symptoms. Arterial pulse intensity should be assessed and should be recorded numerically, as shown in Table 14-5. Table 14-6 outlines some of the important findings on the physical exam of the legs.


Table 14-5 Gradation of Arterial Pulse


















Numerical Gradation Clinical Assessment
0 Absent
1 Diminished
2 Normal
3 Bounding

Table 14-6 Physical Exam Findings of Peripheral Arterial Disease





Limb examination (and comparison with the opposite limb) includes:


Diagnostic Testing







Peripheral Vascular or Endovascular Intervention


Endovascular procedures, or percutaneous catheter-based revascularization techniques, is the group name for techniques used to achieve the nonsurgical revascularization of PAD patients. Endovascular therapy offers several distinct advantages over surgical revascularization:



Problems secondary to endovascular intervention are generally related to bleeding and vascular access.


The evaluation prior to performing endovascular intervention is identical to that for a patient undergoing cardiac catheterization and includes a complete blood count, serum electrolytes, coagulation panel (activated partial thromboplastin time, prothrombin time, international normalized ratio), serum creatinine, glomerular filtration rate, stool guiac, fasting glucose, and an electrocardiogram.




Vascular Access


Successful endovascular intervention requires appropriate choice of vascular access. In most cases, access is obtained using a 21-gauge needle and 0.18-inch wire (4F micropuncture set). The retrograde approach to the common femoral artery (CFA) is the most frequently used vascular access. The inguinal crease is highly variable in relation to the CFA bifurcation in up to 75% of patients. Identifying the femoral head under fluoroscopy is very helpful (Fig. 14-1), as this will help ensure puncture of the vessel above the CFA bifurcation and below the inguinal ligament. Vascular access with the use of ultrasound imaging is also safe and effective as this allows direct imaging of the vessel.



The majority of PVIs can be performed from several access sites (Table 14-7). On most occasions the location of the lesion (to be intervened upon) will determine the most appropriate access site.


Table 14-7 Arterial Access for Different Vascular Territories





















Vascular Access Artery(ies) to Revascularize
Retrograde CFA Arch vessels, renal, & mesenteric
Contralateral CFA Contralateral iliacs, CFA, PFA, SFA, popliteal
Antegrade CFA Mid-distal femoral, popliteal, infrapopliteal
Brachial/radial artery Renal (caudal takeoff), mesenteric, iliac arteries
Retrograde popliteal artery SFA and iliac artery

CFA, common femoral artery; PFA, profunda femoris artery; SFA, superficial femoral artery.


Retrograde CFA access permits selective angiography and intervention of the contralateral pelvic and lower extremity vessels. After gaining retrograde access (Fig. 14-2) to the CFA, the contralateral iliofemoral system is reached by placing a diagnostic catheter with an acute bend at the tip (usually an internal mammary artery [IMA] or Simmons catheter) at the aortic bifurcation. The catheter is manipulated so that the tip “engages” the ostium of the contralateral common iliac artery. A stiff-angled 0.035-inch Glidewire (Terumo Medical Corporation, Somerset, NJ) is then carefully steered to the femoral artery and the diagnostic catheter is advanced over the Glidewire into the CFA. The Glidewire is then exchanged through the diagnostic catheter for a stiff guidewire (Amplatz extra-stiff, Cook, Bloomington, IN), which is advanced into the distal femoral artery. The diagnostic catheter is then removed, leaving the extra-stiff wire in place. A crossover sheath (6 F–8 F) may then be advanced over the stiff guidewire and positioned in the contralateral CFA. This allows contrast injection during lesion dilation and backup support for crossing lesions. This type of sheath manipulation may be very difficult with individuals who have an acute angle between the origin of the common iliac arteries or those who have aortofemoral bypass grafts.



Antegrade CFA access allows for easier treatment of lesions located in the arterial tree just at or below the knee. It is more technically demanding than retrograde CFA access, particularly in obese patients. Antegrade CFA access may carry a higher complication rate than retrograde CFA access. When entering the CFA in an antegrade fashion, it is helpful to identify the femoral head under fluoroscopy. Depending on the amount of subcutaneous tissue, a skin incision is made 1 to 2 cm cephalad to the middle of the femoral head. After the CFA pulse is located at the middle of the femoral head, the percutaneous needle is introduced through the skin incision and directed obliquely and caudally toward the center of the femoral head. Once the CFA has been entered, a steerable guidewire (Wholey, Mallinckrodt, St. Louis, MO) is advanced under fluoroscopic guidance toward the superficial femoral artery (SFA) which runs medial to the profunda femoris artery (PFA). It is important to emphasize that, at their origin, the SFA and PFA overlap in the anteroposterior (AP) fluoroscopic view. To separate them, a lateral oblique view (20–40 degrees) is used. Relative contraindications for the use of this vascular access site include atherosclerotic disease of the CFA or proximal SFA, and extreme obesity.


Retrograde popliteal artery access can be useful when trying to cross an occluded SFA. It is important to be aware of the anatomical relationship between the popliteal artery and vein. At the level of the joint space, the artery courses anterior to the vein, whereas, at approximately 6 cm cephalad to the joint space, the artery is medial to the vein (Fig. 14-3). For popliteal arterial puncture, the vessel should be free of significant disease and larger than 4 mm in diameter. Prior angiography and/or color-flow duplex imaging may provide useful information regarding puncture of this vessel. The first step is to gain contralateral CFA access in order to provide contrast injections to help visualize the target popliteal artery. The CFA sheath is secured in place and the patient is turned to the prone position. Contrast injections performed through the contralateral CFA sheath allow fluoroscopic visualization of the popliteal artery. In this way a micropuncture needle is directed obliquely from medial to lateral so that the artery is entered approximately 5 to 6 cm above the joint space. A 0.035-inch floppy guidewire is then advanced into the popliteal artery, and a 4F to 6F sheath is then inserted.




Nonselective Abdominal Angiography


Vascular access for initial aortoiliac intervention may be performed via brachial, axillary, or femoral artery access. After insertion of a 4 F to 6 F sheath, a pigtail or other “flush” angiographic catheter can be advanced to the level of the mesenteric or renal arteries (approximately lumbar level L1 at the spine) to perform nonselective angiography. The “flush” catheters have multiple side holes and include the tennis racket, straight, and universal (e.g., SOS Omni; AngioDynamics, Latham, NY) catheters. These catheters should generally be advanced over a 0.035-inch wire with a gentle, floppy tip such as a Wholey or other type of steerable wire. This type of 0.035-inch wire is more maneuverable and ultimately more forgiving in patients with severely stenotic or calcified vessels. If there is some difficulty navigating past severely stenotic lesions with these wires, then a 0.035-inch angled and tapered Glidewire may be able to perform this task. Because angiographic contrast is delivered under force, using end-hole catheters during nonselective power injection may damage more fragile, smaller side branch arteries or atherosclerotic plaque, increasing the risk of vessel dissection and trauma. Operators should not inject into small branches of the aorta and should position their catheters safely (below T12), and not directly against the aortic wall. Positioning of catheters above T12 can result in accidental power injection into the artery of Adamkiewicz, which may cause paralysis. The operator should also be aware of the catheter’s maximal flow tolerance, number of side holes, tapering of the tip, and internal diameter of the catheter.


Abdominal angiography is performed in order to evaluate the abdominal aorta, mesenteric vessels, renal arteries, and other visceral vessels. Digital subtraction angiography may be preferred over standard cineangiography. The angiogram can be performed in an AP projection. If there is a specific interest in the renal arteries and the aortorenal junction, then a left anterior oblique (LAO) projection of approximately 5 to 30 degrees may provide better visualization of the origin of both renal arteries. In this particular case the universal and tennis racket catheters may be preferred, as they deploy contrast dye in a caudal direction (rather than the cephalad direction of the pigtail catheter), and so prevent the dilution that may occur with illumination of the celiac trunk and superior mesenteric artery.


Nonselective angiography requires knowledge of image angulations and vascular anatomy to better define disease involving the aortovisceral vessel junction, and other ostial disease. Table 14-8 depicts some useful angiographic views for different vascular territories.


Table 14-8 Most Useful Angiographic Views for Different Vascular Territories







































Artery or Vascular Territory Angiographic View
Aortic arch 30–60 degrees LAO (with slight cranial angulation)
Brachiocephalic vessels (origin) 30–60 degrees LAO
Subclavian AP, ipsilateral oblique with caudal angulation
Vertebral origin AP, ipsilateral oblique with cranial angulation
Carotid extracranial Lateral, AP, ipsilateral oblique
Renal arteries (origin) AP, 5–30 degrees ipsilateral oblique
Mesenteric arteries (origin) Lateral or steep RAO
Iliac artery Contralateral 20–45 degrees oblique and 20o caudal
CFA, SFA, and PFA arteries Ipsilateral 30–60 degrees oblique
Femoropopliteal AP
Infrapopliteal trifurcation and runoff AP

AP, anteroposterior; CFA, common femoral artery; LAO, left anterior oblique; PFA, profunda femoris artery; RAO, right anterior oblique; SFA, superficial femoral artery.




Aortoiliac Intervention


There are various types of aortoiliac occlusive disease and procedures to surgically treat them. The patency rate for these procedures is documented in Table 14-9. Most commonly, the lesions of greatest hemodynamic consequence are located in the iliac arteries. The most effective surgical procedure for the treatment for this type of atherosclerotic disease, and the resultant buttock and thigh claudication, is aortobifemoral bypass. If the aortoiliac lesions are confined to the area of the aortic bifurcation, localized aortoiliac endarterectomy may be considered. Less invasive approaches may be appropriate for patients with adequate aortic flow but stenosis or occlusion of both iliac vessels. Such patients may not be candidates for aortobifemoral bypass because of comorbid cardiovascular disease. If endovascular treatment of one iliac artery is possible and can achieve good results, then a subsequent endarterectomy, unilateral iliofemoral bypass, or femoral-femoral bypass can be considered. In the absence of an inflow stenosis within the iliac arteries, this procedure can provide flow to both lower extremities and eliminate the symptoms of claudication.



Patients with severe distal aortic atherosclerosis who are at high cardiovascular or surgical risk for open aortobifemoral bypass may be treated with axillofemoral-femoral bypass. Because of lower patency rates, such bypasses are reserved for those who have no alternatives for revascularization. Unilateral iliac occlusions that cannot be effectively treated by angioplasty and stent placement can be treated by iliac artery endarterectomy, aortoiliac bypass, aortofemoral bypass, or iliofemoral bypass if the origin of the iliac artery is free of disease. Disadvantages of the surgical method include higher morbidity compared with endovascular therapy.


Endovascular reconstruction options include the following:



The advantages of using percutaneous interventional procedures over bypass surgery (especially to treat chronic limb ischemia) include:



The efficacy of PTA versus stents for lower extremity arterial stenosis has not been demonstrated in randomized trials. PTA of distal abdominal lesions is effective; however, PTA followed by stenting offers greater advantages of larger vessel lumen gain, long-term patency (>70% at 5 years), high procedural success rates (90%), and less thromboembolism. Factors associated with a poor outcome with endovascular therapy include:




Iliac Artery Intervention


Iliac artery intervention is very important, not only for improving flow to the lower extremities but also for cardiovascular therapies such as coronary artery intervention, insertion of an intra-aortic balloon pump, other cardiac output assist devices, or for treatment of vascular access site complications. Retrograde CFA access is the most frequently used access for percutaneous angiography and intervention for both coronary and noncoronary vessels.



Indications


The indications to perform an intervention of the iliac arteries include vascular access and symptomatic lower extremity ischemia. Iliac intervention may also be appropriate in patients with severe stenosis or occlusion of the femoropopliteal or infrapopliteal arteries and concomitant moderate iliac artery disease, in whom revascularizing the moderately stenosed iliac artery may improve the arterial inflow and lead to symptomatic improvement or salvage of the limb. The following highlights some of the indications for revascularization in the patient with intermittent claudication:



Endovascular treatment of significant iliac artery stenosis with claudication is indicated as follows:




Technique


The retrograde ipsilateral CFA access is the most commonly used vascular access for revascularization of the common and external iliac artery. Occasionally, the contralateral, axillary, or brachial access may be necessary when the distal portion of the external iliac and/or CFA artery is involved. Prior to the procedure, the patient should have had a trial of appropriate medical therapy for PAD including antiplatelet therapy with aspirin and/or clopidogrel. Conversely, these medications (especially clopidogrel) can be held when intervening on the iliac arteries in case of possible procedure complications such as vessel perforation or rupture.


After gaining vascular access, heparin is administered (and maintained to a therapeutic activated clotting time). In many cases direct thrombin inhibitors such as bivalirudin are also acceptable for anticoagulation (especially in patients with, or at risk for, heparin-induced thrombocytopenia [HIT] or HIT with thrombosis [HITT]).


After the target lesion has been identified, the reference vessel diameter (RVD) is determined. Peripheral balloon or stent over sizing may lead to tear or rupture of the external iliac artery, and so the use of quantitative angiography or intravascular ultrasound to measure vessel diameter is encouraged. Visual estimation of vessel diameter is discouraged.


Once the lesion has been crossed with a steerable wire such as a Wholey wire or Glidewire, a catheter such as a hydrophilic Glidecatheter (Terumo Medical Corporation, Somerset, NJ) is positioned immediately above the lesion. Universal or pigtail catheters may also be used, as distal abdominal aortograms will also provide excellent bilateral pelvic vessel angiograms. When the lesion is located in the distal common iliac or proximal external iliac artery, retrograde injections of contrast through the femoral sheath may also be used. One particular angiographic view, which separates the origin of the internal and external iliac arteries, is the contralateral caudal oblique view (20 degrees lateral oblique and 20 degrees caudal).


Next the soft-tip guidewire can exchanged for an extra-stiff guidewire (0.035-inch Amplatz wire, Cook, Bloomington, IN) to provide support and trackability for stent placement. The lesion is dilated with a balloon sized 1:1 with the RVD or using the lowest pressure that will fully expand the balloon. The balloon may also be sized smaller than the RVD. The results are assessed by reinserting the catheter above the lesion or using a hand injection of contrast through the sheath. Although provisional stent placement is indicated for use in iliac arteries as salvage therapy for suboptimal or failed result from balloon dilation (e.g., persistent gradient, residual diameter stenosis >50%, or flow-limiting dissection), most experts believe that stenting is effective as primary therapy for common iliac and external artery stenosis and occlusions.


Balloon-expandable stents are preferred when a precise stent placement is required (ostial lesions), and self-expanding stents are preferred when precision is not a critical factor and the vessel tapers in size (Fig. 14-4

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Jun 5, 2016 | Posted by in CARDIAC SURGERY | Comments Off on Peripheral Vascular Intervention

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