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Across countless studies globally, it has been found that individuals with chronic kidney disease are more likely to develop or show signs of peripheral arterial disease than individuals with normal or average kidney function. Nephrology clinical practice of today is often adversely affected by peripheral arterial disease diagnostic challenges, all while patients with kidney disease typically tread a slow path to treatment for peripheral arterial disease. For these reasons, a peripheral vascular specialist and nephrologist partnering with one another can have a powerful positive impact on the health and longevity of their patient by addressing underlying causes which may inhibit their ability to get treatment.

How are Kidney Disease and PAD related?

It is vital to understand the pathology of these diseases in order to properly advance both of their treatments. Peripheral arterial disease is a progressive circulatory condition “caused by narrowing and blockages of the arteries, usually in your legs.” This disease affects “approximately 10 million adults in the United States and more than 200 million adults throughout the world,” and is most commonly brought on as a result of atherosclerosis — the build-up of plaque on the inner walls of the artery. However, chronic kidney disease also contributes to atherosclerosis. Atherosclerosis recognized as a “frequent cause of morbidity in patients with end-stage renal disease.”

Moreover, patients dealing with peripheral arterial disease often experience complications, such as a reduction of blood flow to the extremities, which in turn leads to the slowed or stunted healing of wounds. As a result, individuals living with peripheral arterial disease are prone to infections that may ultimately result in the amputation of limbs. Conversely, chronic kidney disease manifests itself in the form of reduced kidney function.

Risk Factors and Population Trends

Classic risk factors of peripheral arterial disease, such as age, smoking, diabetes, hypertension, and hyperlipidemia are incredibly common in patients with kidney disease. And the presence of peripheral arterial disease in patients “is a strong independent risk factor for increased cardiovascular disease mortality and morbidity, including limb amputation” in individuals with chronic kidney disease. On the other hand, kidney disease also “imposes additional unique risk factors that promote arterial disease,” like “chronic inflammation, hypoalbuminemia, and a pro-calcific state.”

The presence of peripheral arterial disease in individuals afflicted by chronic kidney disease “markedly increases the short term risk of heart attack and stroke, and serves as the key cause of limb loss and mortality, with such rates being much greater than that of the general population.” And the prevalence of both symptomatic (i.e., intermittent claudication and critical limb ischemia) and asymptomatic peripheral arterial disease is greater in individuals with chronic kidney disease, in comparison to the general population as well. In order to properly detect peripheral arterial disease, “health care providers should be aware of the importance of evaluating feet, especially when patients have any symptoms or signs indicative” of peripheral arterial disease. Nevertheless, regular screenings are necessary as many peripheral arterial disease patients are asymptomatic.

As of 2014, the prevalence of peripheral arterial disease amongst American individuals was high, afflicting nearly 4.3% “of the general adult population over 40 years of age.”  Moreover, peripheral arterial disease rates are often significantly higher in patients with chronic kidney disease, specifically end-stage renal disease, who require dialysis.

Additionally, in a 2005 study conducted by the joint efforts of researchers at Johns Hopkins, Duke University, and the University of Minnesota that examined more than 14,000 patients over an average timespan of about 14 years, it was found that patients with chronic kidney disease developed peripheral arterial disease at nearly double the speed of those without chronic kidney disease. This allowed these researchers to confidently conclude that patients with chronic kidney disease are, in fact, at a higher risk for peripheral arterial disease.

There are many hurdles that come along with managing to serious comorbid diseases. Individuals with chronic kidney disease “are less likely to be provided recommended ‘optimal’ PAD care,” but nephrologists can serve as a force for positive change.

Overall, peripheral arterial disease continuously goes undiagnosed and untreated, making it one of the “potent risk markers for cardiovascular morbidity and mortality in patients with kidney disease”. The widespread presence of peripheral arterial disease, combined with the “significant mortality, morbidity, and quality-of-life reduction associated with both diseases,” shines a light on the unavoidable need for nephrologists around the world to comprehend the prospective advantages of both early diagnosis and dynamic management of both diseases. However, although early detection and treatment are imperative to avoiding infections and amputations and to achieving the best outcomes for patients, it is vital to note that “nearly half of all peripheral arterial disease patients have no apparent symptoms, it can be very difficult to know if someone has the disease.”

Nephrologists and Cardiologists make a great Care Team

The teaming up nephrologists and peripheral vascular specialists is the clearest route to more accurate, higher-quality treatment for patients that are affected by both chronic kidney disease and peripheral arterial disease. According to the American Journal of Kidney Diseases, “aggressive risk-factor modification, including treatment of diabetes, hyperlipidemia, and hypertension and smoking cessation, should be mandatory in all patients.” The American Journal of Kidney Diseases also strongly recommends that future investigation be completed to properly evaluate the benefit of “earlier treatment strategies” within the population of chronic kidney disease patients, who are often at high risk for cardiovascular diseases like peripheral arterial disease. Early detection of asymptomatic peripheral arterial disease in patients with chronic kidney disease may also “improve both patient and clinician awareness of the potential significance of future exertional leg symptoms or signs of more advanced” peripheral arterial disease. By working together to increase early-stage detection and care, as well as to better understand how to properly treat the two comorbid diseases concurrently, nephrologists and peripheral vascular specialists worldwide may hope to bring better care and quality of life to their patients.

Peripheral arterial disease, or as it’s more commonly known — PAD, has many causes and is also one of the most under-diagnosed forms of vascular disease. PAD is caused by atherosclerosis — or the build-up of plaque within the arteries inside one’s legs. Atherosclerosis manifests when “the blood vessels that carry oxygen and nutrients from your heart to the rest of your body (arteries) become thick and stiff — sometimes restricting blood flow to your organs and tissues.” Although “healthy arteries are flexible and elastic,” plaque build-up can result in hardening of the arteries over time.  Moreover, atherosclerosis can cause difficulties for patients when walking or performing any physical activity. In more severe cases, PAD can lead to tissue loss, infection, and even limb amputation.  Fortunately, PAD is also easily tested for in the care of a trained vascular surgeon.  Dr. Beheshtian has performed over a thousand PAD cases of varying complexity over her medical career.

Furthermore, patients with PAD are at increased risk for cardiovascular disease. In fact, PAD is often cited as “the major cause of cardiovascular disease.” This is due to the fact that atherosclerosis is a systemic disease that also causes coronary and cerebrovascular problems. The build-up of plaque “narrows the arteries, making it harder for blood to flow through.” The formation of a blood clot can block blood flow and consequently result in a heart attack or stroke.

According to the most recent data from the National Health and Nutrition Examination Survey, 6% of the US population 40 years or older has a low ABI (Ankle-brachial index) of ≤0.9, which indicates the presence of PAD. This translates into approximately 7,000,000 people in the US. ABI is a “simple test that compares the blood pressure in the upper and lower limbs.” By calculating the ratio between “the blood pressure in an artery of the ankle by the blood pressure in an artery of the arm,” medical professionals can determine a patient’s ABI.

The true number of PAD cases has historically been tough to establish. “Even though the American Heart Association estimates that approximately 8 to 12 million Americans have PAD,”  more than half of individuals with a low ABI are asymptomatic (show no symptoms) or express unusual or atypical symptoms.  Population screening methods are done by a wide range of professionals, but it is highly recommended that patients are tested by a doctor with endovascular training to ensure that they’re receiving the best and most accurate diagnosis possible.

PAD Risk Assessment and Symptoms

In addition to older age, major risk factors for PAD include diabetes, smoking, high blood pressure, high cholesterol levels, obesity, and physical inactivity. Currently, smoking and diabetes have shown the strongest association with PAD.  Some signs of disease are:

• Painful cramping in one or both of your hips, thighs or calf muscles after certain activities, such as walking or climbing stairs
• Leg numbness or weakness
• Coldness in your lower leg or foot, especially when compared with the other side
• Sores on your toes, feet or legs that won’t heal
• A change in the color of your legs
• Hair loss or slower hair growth on your feet and legs
• Slower growth of your toenails
• Shiny skin on your legs
• No pulse or a weak pulse in your legs or feet
• Erectile dysfunction in men

Even if you don’t have any of the above symptoms, you should see a doctor — specifically a peripheral vascular specialist — if you are:

• Over the age of 65
• Over the age of 50 and have a history of diabetes or smoking
• Under the age of 50, but have diabetes and other peripheral artery disease risk factors, such as obesity or high blood pressure

Screening Tests by Qualified Doctors

Resting ABI is the most commonly used measurement for the detection of PAD in clinical settings. However, variation in measurement protocols may lead to differences in the ABI values obtained.  This test can often be completed in 10-15 minutes and is best done by a physician with specific training in Peripheral Vascular Disease treatment.

The ankle-brachial index is calculated as the systolic blood pressure obtained at the ankle divided by the systolic blood pressure obtained at the brachial artery while the patient is lying down. A ratio of less than 1 (typically defined as <0.9) is considered abnormal. ABI is typically used to both “diagnose PAD and prevent its progression and [any future] complications.” Moreover, ABI often serves to help “identify people who have a high risk for coronary artery disease.”

PAD Treatment and Interventions

Due to the fact that PAD is a result of systemic atherosclerosis in the lower limbs, treatment of PAD is primarily targeted at (1) reducing morbidity and mortality from lower limb ischemia and (2) preventing cardiovascular disease due to systemic atherosclerosis.

But there is hope for mitigation and/or management of this disease. A patient has the best hope for preventing their condition from worsening if PAD is diagnosed early enough and a treatment plan is adhered to.

In mild cases, there are several ways that an individual can lower their risk of or even reverse PAD. The best remedy is to maintain a healthy lifestyle, which means:

• Quit smoking if you’re a smoker.
• If you have diabetes, keep your blood sugar under control (in normal range).
• Exercise regularly. Aim for 30 to 45 minutes 3-4 times a week after you’ve gotten your doctor’s OK.
• If you have varicose veins in your legs or feet, have them examined beyond their cosmetic considerations
• Lower your cholesterol and blood pressure levels, if applicable.
• Eat foods that are low in saturated fat.
• Maintain a healthy weight (for your age and gender)

In more serious cases of PAD, there are many advanced methods of minimally invasive procedures that, when performed, may reduce or eliminate the instance of PAD.  These cases are best performed by an interventional cardiologist who can give patients a total cardiovascular health solution and help to manage overall risk factors over time.

Dr. Beheshtian is an interventional cardiologist who has trained and performed on over a thousand PAD cases — ranging from mild to extremely complex.  In addition, she has also counseled an abundance of patients on ways to manage their lifestyle — with or without the aid of medication — in an effort to minimize the impacts of PAD on their health and daily life.

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