Understanding Peripheral Artery Disease: Causes and Implications

Danielle Duchaine

Cardiopulmonary Diseases and Disorders

Peripheral Artery Disease

Introduction & Thesis statement

Pathophysiology: the disordered physiological processes associated with PAD, abnormal functioning of diseased vasculature with applications to medical procedures and patient care, emphasizes quantifiable measurements, looks at the specific malfunctioning that comes from or causes disease

Peripheral artery disease is a narrowing and hardening of the blood vessels that supply oxygen and nutrients to the periphery of the body. Arterial occlusion from atherosclerosis could be found in many locations throughout the body; however, the lower extremities are affected more often than the upper extremities. This narrowing is caused by the

buildup of plaque on the arterial walls. Arteries that are affected by PAD become more fibrotic and inflexible, preventing them from widening effectively. This prevents them from dilating to allow greater blood flow when the local oxygen demand increases. This ischemia, or inability to meet oxygen demand, causes pain, and can be classified as being either functional or critical pain. If a patient has functional ischemia, their legs get enough blood supply at rest, but not during exercise. They will have pain with exercise, which will limit their activities, and force them to rest until the pain goes away. (Intermittent Claudication) If the ischemia is classified as critical, the patient will have pain at rest, and may have trophic lesions on their legs or feet.
Incidence: occurance, rate, or frequency of a disease
Approximately 20% of people over the age of 70 have been diagnosed with peripheral artery disease.3 Age decreases the elasticity and integritiy of the arteries, and is therefore an important factor in determining risk for PAD. Gender is also a contributing factor; males are at a higher risk for developing PAD sooner than females.2 Males also are at a higher risk of developing more severe forms of PAD.
Etiology: the cause, set of causes, or manner of causation of PAD, organisms that may cause the disease, risk factors, genetic predisposition. Etiology puts into perspective the causes of disease
There are many conditions that can contribute to the buildup of plaque in arteries, and the hardening of the arterial walls. Tobacco use in any form is the most important contributor to PAD, as smoking promotes atherosclerotic changes in the endothelium of blood vessels. Almost 90% of patients diagnosed with PAD are current or former smokers; smokers’ risk of PAD is positively correlated with the number of cigarettes they smoked each day, and the number of years they smoked for.
Diabetes also increases the risk of PAD by causing dysfunction of the smooth muscle and endothelium of the arteries. The risk of developing PAD is positively correlated with the duration and severity of the patient’s diabetes. Dyslipidemia accelerates the progression of PAD, and hypertension can increase the incidence of intermittent claudication.
Clinical Manifestations: signs and symptoms seen in clinic.
Perpherial Artery Disease typically manifests in the clinic as Intermittent Claudication.
Stages. Around 50%4 individuals with PAD may be asymptomatic.
The symptoms of Peripheral Artery Disease are classified into four different stages. It is important to recognize these stages, as
In stage one, the patient is asymptomatic.

They may not have pain with exercises, however, their distal lower extremity pulses may be weak or absent. In stage two, the patient will have consistently reproducable pain with exercise. Exercise may cause burning and cramping muscle pain, which alleviated by rest. If a patient is in stage three, their symptoms will happen with exercise and at rest. In this stage, the pain may wake the patient up at night, and may be relieved by hanging the leg off of the side of the bed. These patients will prefer sitting with their legs low, as in a recliner, because gravity will help force blood down into their distal lower extremities. This could cause some edema. Pain in stage three is often described as numb, burning, or a toothache-type

pain.
Stage four is the most severe stage, and is categorized by necrosis. The combination of ischemia and edema kills tissue on the toes, forefoot, and heels, causing ulcers. There is often a gangrenous odor emitted by the necrotic tissues.
Medical Diagnosis
Diagnosis of PAD is done by comparing the systolic pressure of the brachial artery to the systolic pressures obtained at the upper thigh, lower thigh, calf, and ankle. The ankle brachial index (ABI) is the ratio of the leg blood pressure to the arm blood pressure. If the pressure in the leg is lower than the arm, the ABI indicates the patient has PAD. By taking the pressure of many locations on the leg, it allows the physician to locate where symptoms are most severe. An ABI between 0.9-1.2 is considered a normal, while a value below 0.9 indicates PAD. If the value is below 0.5, the patient has severe arterial disease with possible tissue necrosis. 3,4
Measurement of ABI can be taken by sphygmomanometer or by Doppler ultrasound, If the patient’s arterial calcification makes it difficult to reliably determine systolic pressure in the leg, the physician can also use plethysmography to graph the patient’s pulse wave velocity.
Prognosis
PAD significantly increases a patient’s risk of ischaemic heart failure, myocardial infarction, unstable angina, cerebrovasuclar disease, and sudden death.4 Approximately 30% of patients diagnosed with PAD die from either a stroke or a heart attack within 5 years.3
7% of PAD patients will need surgical intervention of their affected arteries.

This could involve revascularization procedures like endarterectomy or arterial bypass, or percutaneous catheter interventions involving angioplasty and stent placement. 4% of patients with PAD will need major amputation, and 16% will see an increase in the severity of their intermittent claudication over time.3

Brief Overview of medical and pharmacological Management

Pharmacologic management of PAD typically involves statins, which help manage cholesterol, and antihypertensives to decrease blood pressure. Anti-platelets including aspirin (for later stages) and clopidogrel (Plavix) can be used to reduce the risk of vascular accidents in patients with PAD.4

Cliostazol (Pletal) and pentoxifylline (Trental) are both newer drugs for treating intermittent claudication; they inhibit platelet aggregation and dialate arteries to decrease platelet coagulation and increase blood supply to the lower extremities. 4

Lifestyle changes may also be beneficial to the patient. They should quit smoking, and exercise regularly to improve collateral circulation in the lower extremities.5 If the patient is diabetic, it is important to ensure that their diabetes is well

managed.

References (AMA, minimum 4 peer reviewed)

1) Hernando FJS, Conejero AM. Peripheral Artery Disease: Pathophysiology, Diagnosis, and Treatment. Rev Esp Cardiol. 2007;60:969-82.
2) Hooi JD, Kester AD, Stoffers HE, Overdijk MM, van Ree JW, Knottnerus JA. Incidence of and risk factors for asymptomatic peripheral arterial occlusive disease: a longitudinal study. Amer Jour Epid. 2001;153:7:666-672.
3) Shammas NW. Epidemiology, classification, and modifiable risk factors of peripheral artery disease. Vasc Health Risk Manag. 2007;2:229-34.
4) Violi F, Basili S, Berger JS, Hiatt WR. Antiplatelet therapy in peripheral artery disease. Handb Exp Pharmacol. 2012;210:547-63.
5) Watson L, Ellis B, Leng GC. Exercise for intermittent claudication. Cochrane Database Syst Rev. 2008.