Peripheral artery disease (PAD) is a common circulatory problem that occurs when there is a narrowing or blockage in the arteries that supply blood to the limbs, most commonly the legs. It is estimated that around 8 million people in the United States have PAD, and the prevalence of the disease increases with age. PAD is a significant risk factor for cardiovascular disease (CVD) and is associated with an increased risk of heart attack, stroke, and other cardiovascular events, such as limb ischemia leading to amputation. In this article, we will discuss how PAD increases the risk of CVD and the underlying mechanisms that link the two conditions.
The Link between PAD and CVD
PAD is a manifestation of atherosclerosis, a condition in which plaque accumulates within the walls of arteries, causing them to become stiff and narrow. Atherosclerosis is a systemic disease that can affect any artery in the body, including those that supply blood to the heart and brain. When plaque accumulates in the coronary arteries that supply blood to the heart, it can cause coronary artery disease (CAD), which is the leading cause of death worldwide. Similarly, when plaque accumulates in the carotid arteries that supply blood to the brain, it can cause carotid artery disease, which is a major risk factor for stroke.
PAD and CVD share many common risk factors, such as age, smoking, high blood pressure, diabetes, and high cholesterol. The accumulation of plaque in the arteries is a complex process that involves inflammation, oxidative stress, and immune dysfunction, which are also involved in the development of CVD. However, the mechanisms by which PAD increases the risk of CVD are not entirely clear and are likely to be multifactorial.
One possible mechanism is that PAD can lead to reduced blood flow to the heart and brain, which can cause ischemia and hypoxia. Ischemia refers to a lack of blood supply, while hypoxia refers to a lack of oxygen supply. These conditions can lead to the development of atherosclerosis, which further narrows the arteries and exacerbates the ischemia and hypoxia. In the heart, this can lead to angina pectoris (chest pain) or myocardial infarction (heart attack). In the brain, this can lead to transient ischemic attack (TIA) or stroke.
Another possible mechanism is that PAD can cause endothelial dysfunction, which is a condition in which the cells that line the arteries (endothelial cells) do not function properly. Endothelial dysfunction is a hallmark of atherosclerosis and is characterized by reduced production of nitric oxide, which is a vasodilator that helps to regulate blood flow and prevent platelet aggregation. When endothelial cells are dysfunctional, they produce less nitric oxide, which can lead to vasoconstriction, platelet aggregation, and thrombosis. These processes can contribute to the development of CVD by causing coronary artery spasm, thrombosis, or plaque rupture.
In addition to these mechanisms, PAD and CVD may also share common genetic factors. Recent genome-wide association studies have identified several genetic loci that are associated with both PAD and CVD, indicating that there may be shared pathways involved in the pathogenesis of the two conditions. However, more research is needed to understand the genetic basis of PAD and CVD and their interactions with environmental factors.
Prevention and Treatment
Given the strong link between PAD and CVD, it is important to prevent and treat PAD as early as possible. Lifestyle modifications, such as smoking cessation, regular exercise, and a healthy diet, can help to reduce the risk of both PAD and CVD. In addition to prevention, there are treatments once the diagnosis of PAD has been established. The common treatments include medications such as statins, antiplatelet and anticoagulation agents, and blood pressure-lowering drugs can help to reduce the risk of cardiovascular events in patients with PAD. For severe atherosclerotic disease with major symptomatic blockages or occlusions, PAD, CAD and CVD are treated with both minimally invasive catheter techniques and surgical procedures.