I.
Review of Vascular Anatomy
Fig. 1: Common femoral artery (1), Superficial femoral artery (2), Deep femoral artery (3), Lateral circumflex artery (4), Descending genicular artery (5), Popliteal artery (6), Anterior tibial artery (7), Posterior tibial artery (8), Fibular artery (9), Dorsalis pedis artery (10), Plantar arch (11), Plantar metatarsal arteries (12), Lateral plantar artery (13).
References: Department of Diagnostic Radiology, University of Puerto Rico
Fig. 2: Left vertebral artery (1), Thyrocervical trunk (2), Internal thoracic artery (3), Thyroicervical trunk (4), Thoraco-acromial artery (5), Subclavian Artery (6), Anterior circumflex artery (7), Posterior circumflex artery (8), Subscapular artery (9), Circumflex scapular artery (10), Lateral thoracic artery (11), Brachial artery (12).
References: Department of Diagnostic Radiology, University of Puerto Rico
Fig. 3: Brachial artery (1), Radial artery (2), Common interosseous artery (3), Anterior interosseous artery (4), Recurrent interosseous artery (5), Posterior interosseous artery (6), Ulnar artery (7). Left hand arteriogram (b): Deep palmar arch (1), Superficial Palmar arch (2), Princeps pollicis artery (3), Proper digital arteries of thumb (4), Palmar metacarpal arteries (5), Proper palmar digital arteries (6).
References: Department of Diagnostic Radiology, University of Puerto Rico
II.
Epidemiology and Risk Factors
Fig. 4
References: Adapted from Lee, Y. E., Patel, P. M., & Ferri, F. F. (n.d.). Peripheral artery disease. In Ferri's Clinical Advisor (pp. 1052-1056). Philadelphia, PA: Elsevier.
III.
Clinical Presentation
Fig. 5
References: Adapted from Lee, Y. E., Patel, P. M., & Ferri, F. F. (n.d.). Peripheral artery disease. In Ferri's Clinical Advisor (pp. 1052-1056). Philadelphia, PA: Elsevier.
Though the majority of patients are asymptomatic,
the classic presentation of PAD is intermittent claudication.
Patients complain of lower limb muscle pain,
cramping or weakness induced by walking a consistent distance,
that is relieved after 10 to 15 minutes of rest.
Symptoms arise in the muscle groups located one joint level below the region of arterial occlusion.
Calf claudication is most common,
given that the superficial femoral artery is the most frequently affected by atherosclerosis.
Nonetheless,
thigh or buttock pain may also arise as a result of proximal aortiliac disease.
Critical limb ischemia (CLI),
on the other hand,
is the most severe form of disease.
It involves lower limb pain present even at rest,
or tissue loss via non-healing ulcers and gangrene.
Pain is exacerbated at night when the foot is in a non-dependent position and is only responsive to narcotics.
About 25% of patients with CLI require a major amputation at 1 year (20).
IV.
Staging of Disease Severity
Fig. 6
References: Adapted from Fontaine R, Kim M, Kieny R. Surgical treatment of peripheral circulation disorders [in German] Helv Chir Acta. 1954;21(5–6):499–533; Rutherford R B, Flanigan D P, Gupta S K. et al. Suggested standards for reports dealing with lower extremity ischemia. J Vasc Surg. 1986;4(1):80–94; Rutherford R B, Baker J D, Ernst C. et al. Recommended standards for reports dealing with lower extremity ischemia: revised version. J Vasc Surg. 1997;26(3):517–538.
V.
Diagnosis
Diagnosis of peripheral artery disease may be evident from a history of risk factors,
clinical presentation and relevant physical exam findings.
Non-invasive,
lower extremity arterial testing may then be performed to support the diagnosis and aid in localizing the site of stenotic lesions.
A.
Ankle-Brachial Index (ABI) (2)
- Preferred non-invasive arterial testing modality
- Sensitivity ~ 95%
- Specificity ~ 100%
-
Cost-effective
-
Office-based
- Calculated as a ratio of the higher systolic blood pressure measured at the ankles (dorsalis pedis and posterior tibial arteries) to that of the arms (brachial arteries),
after the patient has been supine for five to ten minutes
Other non-invasive arterial testing modalities include:
- Segmental Blood Pressures
- Continuous Doppler Waveforms
B.
Imaging
1.
Duplex Ultrasonography
- Combines ultrasonography with Color Doppler
- Identifies turbulent blood flow and doppler ‘aliasing’ to localize luminal narrowing
- Measures Peak Systolic Velocity (PSV) interval changes.
- Stenosis of ≥50% is identified upon measurement of PSV in a diseased segment that is more than twice the PSV in the proximal segment.
- Sensitivity of 88% and Specificity of 96%,
as compared to angiography
- Disadvantages: Time-consuming and operator-dependent
Fig. 7: Color and spectral Doppler (a), (b) and (c) shows a focal high-grade stenosis in the mid left Superficial Femoral Artery (SFA), with pre-stenotic maximum velocities of 75.6 cm/s and post-stenotic maximum velocities of 194 cm/s. Left lower extremity angiogram demonstrate a high-grade stenosis (more than 90%) in the mid to distal portion of the left SFA, correlating with Doppler findings.
References: Department of Diagnostic Radiology, University of Puerto Rico
2.
Computed Tomography Angiography (CTA) and Magnetic Resonance Angiography (MRA)
Fig. 8
References: Department of Diagnostic Radiology, University of Puerto Rico
3.
Conventional angiography
- Remains the gold-standard imaging modality for PAD
- Allows detailed visualization of arterial anatomy and extent of disease due to iodinated contrast injection
- Disadvantages:
- Requires use of iodinated contrast agents
- Exposure to ionizing radiation
- Invasive nature
VI.
Management
Fig. 9
References: Adapted from Kullo, I. J., Kellerman, R., & Bope, E. (2018). Peripheral artery disease. In Conn's current therapy 2018 (pp. 141-146). Philadelphia, PA: Elsevier.
- Dependent of clinical presentation and impact on quality of life
- First-line therapy for patients with intermittent claudication relies on:
-
Medication
- Goal: reduce cardiovascular morbidity and mortality and improve lower extremity outcomes
- Involves use of lipid-lowering agents,
antihypertensives and antiplatelet therapy
- Risk Factor Modification
- Smoking cessation
-
Supervised Exercise Rehabilitation Program
- Minimum of three 30-45 minute sessions per week,
for 12 weeks (TASC II and ACC/AHA)
- Goal: improve walking distance and stabilize symptom progression with development of collateral flow and gait alterations (4)
- Patients with persistent symptoms (Rutherford Class 2 or 3) despite medical therapy are then evaluated for revascularization procedures.
- First-line therapy for patients who instead present with critical limb ischemia or gangrene (Rutherford Class 4,
5 or 6) are evaluated for revascularization initially,
bypassing trial of medical therapy and exercise rehabilitation program.
- Given increased perioperative cardiovascular morbidity in these patients,
revascularization through surgical bypass should be employed when an endovascular approach has failed or is not anatomically feasible (9).
VII.
Endovascular Management of PAD
A.
Aortoiliac Disease (Fig. 19)
-
Percutaneous revascularization is now considered first-line treatment
-
Majority of interventions involve stent placement:
- About 40-50% of patients require stent placement after balloon angioplasty of iliac artery stenosis (14)
- Balloon-expandable stents generally preferred (8)
- Placement of “Kissing stents” is an alternative for disease involving one or both ostia of common iliac arteries and distal aorta; it is avoided when possible to preserve contralateral access for potential need of limb arterial intervention in the future (8)
B.Femoropopliteal Disease (Fig. 23)
Superficial femoral artery (SFA): most common site for atherosclerosis in the lower limbs
Endovascular approach is dependent on anatomic considerations and length of occlusive lesions:
- Balloon Angioplasty
- Modality of choice for short segment stenosis (20)
- Stent Placement
- Preferred for longer lesions (>100mm)
- Self-expanding Nitinol stents are favored in this territory (20)
- Increased risk of stent fracture due to biomechanical stress
- Trials with drug-eluting stents have shown less restenosis rates than balloon angioplasty both with and without provisional stenting (8)
C.
Infrapopliteal Disease
- Revascularization of tibial arteries→ indicated in patients with critical limb ischemia
-
Goals: promote wound healing,
relief of pain and limb salvage (13)
-
Intermittent claudication is rarely an indication
- Balloon angioplasty is the preferred endovascular approach
- Limitations
VIII.
Endovascular Tecniques for Revascularization
A.
Balloon Angioplasty (Fig. 17, Fig. 18)
Fig. 10
References: Adapted from Sarin, S. N., Zeitler, E., Loose, R., Vasudevan, P., & Venbrux, A. C. (2014). Angioplasty. In Image-guided interventions (2nd ed., pp. 109-122). Philadelphia, PA: Elsevier
- Based on fracture of atheromatous plaque by expansion of arterial lumen (8)
- Remains mainstay of treatment for revascularization of short arterial occlusions in femoropopliteal disease
- Demonstrated technical success rates of >95% with reduced risk of complications (17)
- There are two types of balloon catheters –depicted in the table below:
Fig. 11
References: Adapted from Sarin, S. N., Zeitler, E., Loose, R., Vasudevan, P., & Venbrux, A. C. (2014). Angioplasty. In Image-guided interventions (2nd ed., pp. 109-122). Philadelphia, PA: Elsevier
- Complications:
- Vessel dissection→rates may be reduced with sustained inflation with low-pressure angioplasty balloon
- Thrombosis
- Possible distal embolization
- Outcomes:
- Success and long-term patency rates of angioplasty will depend on: stage of disease,
anatomic location of obstructive lesions,
extent of disease,
integrity of runoff arteries,
and patient comorbid conditions (ie,
DM,
renal disease,
etc).
- One to three month patency rates after angioplasty (14):
- Iliac artery stenoses: 93%-96%
- Femoropopliteal arteries: Occlusions up to 3cm in length: 82%-87%
Subintimal angioplasty and Subintimal Arterial Flossing with Antegrade-Retrograde Intervention (SAFARI) techniques Fig. 20
Fig. 12
References: Adapted from Hendricks, Nicholas J. et al. Subintimal Arterial Flossing With Antegrade-Retrograde Intervention (SAFARI) and Rertograde Access for Critical Limb Ischemia. Techniques in Vascular & Interventional Radiology. 2014; 17: 203 - 210.
B.
Stent Placement (Fig. 19)
- Preferred approach of management for aortoiliac disease
- Indications for use in femoropopliteal disease (FPD) remain controversial
- Demonstrated superiority (vs PTA) in treatment of long,
heavily calcified atheromatous lesions
- RESILIENT I and II Trials→ compared primary stenting to PTA (with optional stenting) in patients with FPD
- Resulted in 80% of primary patency in stenting group,
vs 38% in the PTA group –as determined by duplex ultrasound (20)
- Two fundamental classes of stents,
based on mode of expansion:
Fig. 13
References: Adapted from Maeda, K., & Ohki, T. (2019). Endovascular therapeutic technique. In Rutherford's vascular surgery and endovascular therapy (9th ed., pp. 762-784). Philadelphia, PA: Elsevier.
- Limitations
- Restenosis
- Suceptibility of fracture
- Thrombosis (Fig. 22)
C.
Atherectomy
-
Involves physical removal of atherosclerotic plaque from the blood vessel (4)
-
Has not proved superior to balloon angioplasty in direct comparisons from most arterial beds (9)
-
Best used as adjunctive procedure→improves recanalization rates in small caliber or heavily calcified vessels,
and those in regions subject to repetitive forces (eg,
over joints)
-
Devices:
- Directional atherectomy
- Rotational atherectomy
- Rotablator
- Orbital atherectomy
Technique:
-
Excisional Atherectomy (Fig. 24)
-
Involves actual removal and collection of obstructive plaque
-
Directional atherectomy device is most commonly used: angulation of catheter tip allows blade to be placed directly against atheroma
-
Use limited by heavily calcified atheromas
2.
Laser Plaque Ablation (Fig. 21)
- Involves fragmentation of plaque into smaller particles
- Excimer Laser is most commonly used laser system
- Converts atheromatous plaque to water and carbon dioxide through process of contact photoablation
Complications:
-
May lead to distal embolization of plaque into microvessels
-
Other complications include pseudoaneurysm,
dissection,
vessel perforation.
(Fig. 25)
D.
Thrombolysis
-
Percutaneous intraarterial thrombolysis is indicated in patients with acute-onset claudication and limb-threatening ischemia.
-
Absolute contraindications includes active bleeding,
irreversible limb ischemia,
recent stroke ( TIA within 2 months or CVA within 6-12 months),
intracranial neoplasm or recent craniotomy and mobile left heart thrombus.
-
Other relative contraindications include history of GI bleeding,
recent major surgery/biopsy and coagulopathy among others.
-
Devices: End-hole vs multi-sidehole catheters are available.
Multi-sidehole catheters vary based on the length of the effective infusion segment.
Technique:
Fig. 14
References: Adapted from Raymond W. Liu, Hani H. Abujudeh, David W. Trost and Krishna Kandarpa. Acute Lower Extremity Ischemia. Image-Guided Interventions 2014 Chapter 33, 172-179.e1
Complications:
IX.
Drug Delivering Technology: A Durable Alternative
Growing prevalence of PAD among an aging population has fueled the advent of innovative solutions to the limitations of current endovascular therapies.
Major challenge of traditional PTA and BMS→Neointimal hyperplasia→ physiologic response to mechanical vascular injury,
leading to:
Alternative
- Incorporation of lipophilic antineoplastic and immunosuppressive agents into balloon and stent devices (eg,
Paclitaxel and Sirolimus)
A.
Drug-Coated Stents
The typical structure of a drug-covered stent (DCS) is outlined in the figure below:
Fig. 15
References: Adapted from Sarode, K., Spelber, D. A., Bhatt, D. L., Mohammad, A., Prasad, A., Brilakis, E., & Banerjee, S. (2014, August). Drug delivery technology for endovascular management of infrainguinal peripheral artery disease. JACC: Cardiovascular Interventions, 7(8), 827-839. doi:10.1016/j.jcin.2014.05.008
-
Ongoing incorporation of bioabsorbable materials into stent design
-
Newer designs have even consisted of a direct coating of the drug into the outer surface of the stent,
foregoing the use of a matrix.
-
Trials comparing the efficacy of DCS to both bare-metal stenting (BMS) and balloon angioplasty show promising results.
B.
Drug-Coated Balloons
Provide an alternative to some limitations of stenting,
including stent fracture and metal or polymer-induced restenosis.
The structure of a typical drug-coated balloon (DCB) is outlined in the figure below:
Fig. 16
References: Adapted from Sarode, K., Spelber, D. A., Bhatt, D. L., Mohammad, A., Prasad, A., Brilakis, E., & Banerjee, S. (2014, August). Drug delivery technology for endovascular management of infrainguinal peripheral artery disease. JACC: Cardiovascular Interventions, 7(8), 827-839. doi:10.1016/j.jcin.2014.05.008
Multiple randomized clinical trials comparing DCB to traditional PTA have shown:
- Reduced target lesion revascularization rates
- Increased primary patency at 6 months,
measured by angiography