Setting: ambulatory care center
CC: “My legs hurt when I walk.”
VS: R: 14 breaths/minute; BP:145/86 mm Hg; P: 70 beats/minute; T: 99.8°F
HPI: A 74-year-old man comes to your clinic with pain in his left leg that he says he has felt for the past few months. The pain localizes predominantly to the calves and is related to walking and is relieved when he sits down to rest. The pain is described as “soreness” and “aching” or “like being punched.” He is able to walk for three to four blocks before it occurs and until recently, has not been overly limited in his mobility.
PMHX:
Hypertension
Diabetes
Tobacco smoking
Medications:
Metformin
Nifedipine
PE:
Cardiovascular: S4 gallop
Extremities: pale, pulses are palpable in dorsalis pedis area
Which physical finding should you check for?
a. Enlarged liver
b. Loss of hair and sweat glands in legs
c. Enlarged spleen
d. Ascites and hemorrhoids
Answer b. Loss of hair and sweat glands in legs
Peripheral arterial disease (PAD) predisposes to loss of skin appendages such as hair follicles and sweat glands. Pulses are lost in very late disease.
S4 is heard with atrial systole into a noncompliant left ventricle.
What is the best initial step?
a. Angiography
b. Ankle-brachial index (ABI)
c. Refer to vascular surgery
d. Doppler ultrasounds of lower extremities
Answer b. Ankle-brachial index (ABI)
ABI is the clear first choice in the evaluation of PAD. It serves to establish a diagnosis, although it does not determine the precise location of the lesion. An ABI <0.9 indicates vascular disease.
It is premature to go straight to angiography. Angiography is the most accurate test, but it is not the one to establish an initial diagnosis of PAD. It can reveal the anatomic location to determine the site of repair.
Doppler ultrasounds are not needed if you can feel a pulse. They are also not as important as determining the difference in BP between upper and lower extremities. You should not refer to vascular surgery for a simple diagnostic procedure such as ABI, which you can do.
In the upright position, where is BP the highest?
a. Brain
b. Carotid
c. Brachial
d. Legs
Answer d. Legs
BP is greater in the legs than the arms when standing because of the effect of gravity. The difference is based on a patient’s height, but it would be expected to be at least 60 to 80 mm Hg greater in the lower extremities. When lying flat, BP should be equal in the arms and legs. If, when lying flat, BP is more than 10% less in the legs than in the arms (ABI <0.9), obstruction to flow is present. Severe PAD is an ABI <0.6.
Initial Orders:
ABI
Lipid panel (low-density lipoprotein [LDL], total cholesterol)
CHEM-7
CBC
ECG
Glycated hemoglobin (HbA1c)
The patient returns the following week to discuss the results of the ABI. His value is 0.7. His symptom of pain when walking several blocks is the same.
Laboratory Test Results:
CBC: normal
CHEM-7: normal
LDL: 145 mg/dL
ECG: LV hypertrophy
HbA1c: 7%
Which BP medication is best for PAD?
a. ACE inhibitor
b. Beta-blocker
c. CCB
d. Diuretic
e. Alpha-1-antagonist
Answer a. ACE inhibitor
ACE inhibitors have some impact in modifying the progression of disease in PAD. CCBs are not particularly effective in PAD. The benefit of a CCB, alpha-antagonist, and diuretic are not more than the benefit of simply controlling BP. There is no disease-modifying effect of the medications listed above on PAD.
CCBs do not benefit the atherosclerotic plaque in the intimal lining of vessel.
Smooth muscle in arteries is exterior to the intimal lining; relaxing it does not open the vessel in PAD.
You switch the nifedipine to lisinopril and add aspirin. You begin the discussion of tobacco cessation by asking if the patient has a goal to stop smoking and try to arrange follow-up to set a quit date. On CCS, remember to always do patient counseling on all lifestyle issues such as weight loss, exercise, diabetic diets, and tobacco cessation. All “population health” issues are major concerns of the Step 3 examination. This can be very difficult to remember for residents trained to focus only on current symptoms in a patient.
Which medication is most effective in PAD?
a. Ticlopidine
b. Cilostazol
c. Pentoxifylline
d. ACE inhibitors
Answer b. Cilostazol
The single most effective medication in PAD is cilostazol. This is a medication that is used for only this single indication. It is not used for coronary, carotid, or cerebrovascular disease. Ticlopidine is a nearly extinct drug to inhibit platelets. It is a P2Y ADP receptor antagonist like clopidogrel, but should rarely be used because of neutropenia and thrombotic thrombocytopenic purpura (TTP). Pentoxifylline is an older medication for PAD that has been replaced by cilostazol.
Ticlopidine can be offered as a wrong answer choice on the Step 3 examination. Ticlopidine causes neutropenia and TTP.
What is the mechanism of cilostazol?
a. Thrombin inhibition
b. Decrease cyclic adenosine monophosphate (cAMP)
c. Increases plasmin activation
d. Phosphodiesterase inhibition
e. Inhibits calcium activation of clotting cascade
Answer d. Phosphodiesterase inhibition
Cilostazol inhibits phosphodiesterase. This increases cAMP. There is both inhibition of platelet activation and some inhibition of vascular smooth muscle. It both prevents platelet aggregation and has some vasodilatory effect.
Pentoxifylline increases “rheology” or diapedesis of red blood cells—great mechanism, no clinical benefit.
Metformin is fine in PAD. No disease management (DM) regimen is superior to another in PAD.
End all ambulatory cases with education, counseling, or advising on lifestyle issues:
• Obesity: weight loss
• Diabetes: diet and exercise
• Hypertension: diet and sodium restriction
• Hyperlipidemia: weight loss
The results of the repeat LDL test is 142 mg/dL. The patient has started lisinopril and aspirin and continued his metformin.
What should be done about his LDL level?
a. Diet and exercise alone for 3 to 6 months and repeat
b. Statin
c. Niacin
d. Ezetimibe
Answer b. Statin
PAD is equivalent to coronary disease, so it is important to lower the LDL to <100 mg/dL in patients with PAD. With an LDL of 142 mg/dL, diet, exercise, and weight loss are insufficient to control the level. Statins are therapeutically equivalent for use on Step 3. Niacin is not as effective as a statin. Niacin is relatively contraindicated in diabetes because it can cause glucose elevation.
Ezetimibe lowers LDL, but has no proven mortality benefit or proof that it alters the natural history of any form of vascular disease.
Get LDL cholesterol <100 mg/dL in PAD—the same as in coronary disease.
Which is most effective to help stop smoking?
a. Education methods
b. Nicotine gum
c. Nicotine patch
d. Bupropion
Answer d. Bupropion
Nicotine patches and gums are more effective than education alone, but bupropion or varenicline is more effective than nicotine replacement.
Advance the clock 2 to 4 weeks. The patient returns using an ACE inhibitor, cilostazol, metformin, and aspirin. He wants to try to stop smoking and agrees to start bupropion and return for follow-up in 2 weeks. The pain is unchanged. Over the next 6 months, the patient stops smoking. Repeat LDL is 85 mg/dL and BP 124/78 mm Hg. On CCS, you never know where the case will stop. Keep advancing the clock. Your case may not have the happy ending this one does. If symptoms worsen in your case despite maximum medical therapy, do an angiogram in preparation for revascularization angioplasty or bypass.
BP goal with PAD is <130/80 mm Hg.
Which of these is a standard preventive measure in this patient?
a. Abdominal aorta ultrasound
b. Chest computed tomography (CT)
c. Exercise tolerance test
d. Renal artery stenosis screening
e. Prostate specific antigen (PSA)
Answer a. Abdominal aorta ultrasound
All men who were ever smokers need an ultrasound to exclude aneurysm. This should be done once between the ages of 65 and 75 years. This is not true for women or nonsmokers. PSA is not recommended for any group. There is no lung cancer screen with chest CT for smokers that is clearly effective or recommended.
Exercise tolerance testing is not a screen for asymptomatic patient. Abdominal aortic aneurysm (AAA) screening is standard for asymptomatic persons.
For statins, liver function tests are standard, not creatinine kinase (CK) levels.