CardioNerds (Drs. Amit Goyal, Jason Feinman, and Tiffany Dong) discuss Beyond the Boards: Diseases of the Peripheral Arteries with Dr. Amy Pollak. We review common presentations of peripheral vascular disease, ranging from aortic disease to the more distal vessels in an engaging case-based discussion. Dr. Pollack talks us through these cases, including the diagnosis and management of peripheral vascular diseases. Show notes were drafted by Dr. Matt Delfiner and episode audio was edited by student doctor Tina Reddy.

The CardioNerds Beyond the Boards Series was inspired by the Mayo Clinic Cardiovascular Board Review Course and designed in collaboration with the course directors Dr. Amy Pollak, Dr. Jeffrey Geske, and Dr. Michael Cullen.

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1. Risk factors for abdominal aortic aneurysm include traditional atherosclerotic risk factors such as age, hypertension, hyperlipidemia, and tobacco use.
   
2. Screening for AAA should be for men over the age of 65 years with a history of tobacco use. If present, medical management includes blood pressure and lipid lowering therapies to decrease the risk of expansion. Decision for surgical intervention relies on size and rate of growth of AAA, with clear indications if it grows> 10 mm in a year or diameter of 5.5 cm in men and 5.0 cm in women.
   
3. When diagnosis of PAD is not straightforward (presence of symptoms but ABI is normal), an exercise ankle-brachial index (ABI) test can be useful. An exercise-induced decrease in ABI by 20% or in ankle pressure by 30 mmHg is consistent with PAD.
   
4. For PAD, treatment with low dose rivaroxaban and aspirin yields lower event rates than with antiplatelet therapy alone. This in combination with lifestyle therapies (diet + exercise) and risk factor management (hypertension and hyperlipidemia) are the cornerstones of therapy. Revascularization is indicated for continued PAD symptoms despite conservative therapy.
   
5. Acute limb ischemia is an “acute leg attack” and is a life-threatening emergency. Common symptoms include pain, pallor, pulselesess, parasthesias, cold temperature (poikilothermia), and paralysis. Restoration of blood flow is paramount, and emergent or urgent revascularization is the first line therapy for those with symptoms < 2 weeks.
   

Learning Objectives:

1. Describe screening and therapeutic strategy for AAA management.
   
2. Understand the risk factors and diagnosis of peripheral arterial disease.
   
3. Compare different management approaches for PAD.
   
4. Be able to recognize acute limb ischemia.
   
5. Describe the overall treatment strategy for acute limb ischemia.
   

Abdominal Aortic Aneurysms

Abdominal aortic aneurysms are a source of high morbidity and mortality. The US Preventative Services Task Force recommends one time screening ultrasound for AAA in men older than 65 years of age with a tobacco use history. Risk factors include age, hypertension, hyperlipidemia, and tobacco use. Patients with AAA between 3-3.9 mm should be monitored every 2-3 years. Sizes 4-5 cm should be re-imaged every 6-12 months.  Additional screening can be done for individuals < 65 years who have a first degree relative with AAA.

Women are more likely to have aortic dissection at smaller diameters than men, which is why intervention (open vs endovascular repair) is recommended at 5 cm diameter for women versus at 5.5 cm for men. Additionally, repair is also warranted if a AAA grows more than 5 mm in 6 months or 10 mm in one year.

Risk factor management is key with AAA, including blood pressure, glucose, and lipid targeting.  The presence of an AAA should be treated as secondary ASCVD prevention like coronary arterial disease, since AAA is an atherosclerotic disease equivalent. Tobacco cessation is of the utmost importance here.

Regarding strategy for repair: if the patient is not a surgical candidate, then endovascular repair is a reasonable option. If they are a surgical candidate, then the location of the aneurysm comes into play. Infrarenal or juxtarenal disease are more likely to require open repair.

Peripheral Arterial Disease

When a patient presents with claudication, in addition to thorough history and physical exam, checking for ABIs is important. Risk factors include known coronary disease, hypertension, hyperlipidemia, and diabetes. Women often report cramping in their calves/legs rather than outright pain.

ABI < 0.9 are consistent with PAD, with > 1.3 consistent with calcified and non-compressible vessels. Toe brachial index (TBI) cutoff is 0.7. If there is strong clinical suspicion but normal ABI, then performing the test after a period of exercise (calf raises, treadmill) can be clinically useful. An exercise induced decrease in ankle pressure by 30 mm or change in ABI by 20% is consistent with PAD.

Therapy for PAD includes supervised exercise training, lifestyle changes (e.g., tobacco cessation) and risk factor modification (blood pressure/lipids/glucose). Additionally, low dose rivaroxaban (2.5 mg twice daily) plus aspirin has been shown to decrease events compared to aspirin alone.

If there are continued symptoms despite the above therapy, then invasive management can be considered. This includes percutaneous or surgical revascularization.  This would be proceeded with CTA imaging for further guidance. Invasive angiography is reasonable for someone with a higher likelihood of a single lesion amenable to percutaneous repair.  Discrete and singular lesions are usually repaired percutaneously while more diffuse or multivessel disease, then surgical management may be indicated.

Acute Limb Ischemia

ALI can present with the 6 Ps: pain, pallor, pulselessness, parasthesias,  poikilothermia, and paralysis. Limbs may (rarely) remain viable, with signs being a clear Doppler-able pulse without sensory or muscle loss. Otherwise, a limb is salvageable if there is a faint arterial Doppler signal. If there is muscle weakness, then the limb is considered threatened. If an arterial Doppler signal is completely lost, then the limb is considered non-viable.

ALI is an “acute leg attack.” The initial therapy is systemic anticoagulation with unfractionated heparin. If symptoms have been present for less than two weeks, then endovascular therapy with either thrombectomy or catheter-directed lysis are indicated. Major contraindications to lytic therapy include recent surgery, any history of intracranial bleeding or neoplasm, or if they are otherwise at a high bleeding risk. Non-viable limbs may better be served with amputation rather than revascularization.

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