We have two types of blood vessels: arteries and veins. Arteries carry oxygenated blood that is pumped from the left side of our heart to be delivered to all parts of our body. Veins return blood from all parts of our body to the heart. Arteries have thicker walls than veins as arterial blood contain blood pressure that is generated by the heart. Arteries have three layers in the construct of its wall; an inner most lining (endothelium) that is in contact with blood flow, a middle muscular layer (media) that allows the elastic tube to constrict and dilate, and an outermost layer (adventitia) that is the strength layer that holds everything together. Other than life-giving oxygen, arterial blood also delivers nutrients to every cell in our body for normal metabolism and function.
Atherosclerosis is the abnormal process where cholesterol is deposited between the endothelial and media layers of arterial wall. This incites repeated inflammation and pathological deposition of calcium, leading to bulky plaque formation that can narrow or block the flow channel (lumen) of the artery. Consequently, flow to the vascular bed downstream is reduced and the organ involved can be damaged. The atherosclerotic plaque surface on the luminal side that is in contact with blood flow can be unstable and ulcerate or rupture. Fatty cholesterol-calcium debris can break off and travel downstream (embolize) with blood flow to block and cut-off blood supply to a vital organ. The ruptured and denuded plaque surface is also prone to clot (thrombus) formation, which can either embolize or occlude the already narrowed part of the diseased artery, both which impair blood flow distally. Risk factors for atherosclerosis and development of disease include: aging, high blood pressure, diabetes, smoking, high blood cholesterol and lipid levels.
Atherosclerosis can affect any vascular bed and are known as different conditions. Coronary Artery Disease is where the blood supply to the heart muscle (coronary arteries) develop narrowings/blockages that reduce blood flow to the muscle of the heart (myocardium). This can cause chest pain (angina pectoris) during physical exertion, or if a coronary artery suddenly and completely clots off (thrombus formation)- can lead to acute coronary syndrome (ACS), heart attack (acute myocardial infarction/AMI), or sudden cardiac arrest. Carotid Artery Disease affects neck and brain arteries (in the neck and skull), where narrowings and turbulent flow cause small clots to form. Similarly, plaques can ulcerate and clots/cholesterol debris can flow into the brain to cause strokes. Mesenteric Ischemia can be acute or chronic and they affect the blood supply to the digestive (gastrointestinal) system. Acute mesenteric ischemia can lead to segmental necrosis (death) of the intestines that require emergency surgery for resection and survival. Chronic mesenteric ischemia can lead to severe abdominal pain after meals, food fear, weight loss and failure to thrive. Peripheral Arterial Disease affects arteries of the lower extremities where reduced blood flow can cause pain the calves, thighs or buttocks, which impairs one’s walking ability. In severe chronic limb threatening ischemia (CLTI), the blood supply is so low and critical that spontaneous wounds or ulcers develop, infections spread rapidly, and frank gangrene can occur in toes, feet, or legs. CLTI carries a high risk of amputation (20% – 40%) and mortality (up to 20%).
Aneurysms are bulges in an artery where the wall is weakened and blood pressure that is normally contained within threatens to burst the vessel. Aneurysmal rupture causes rapid and severe bleeding (exsanguination), and acute reduction of blood flow to the vascular bed/organ that the affected artery normally supplies. Aneurysms can occur in the largest artery in the body, the aorta, or any artery branch including the cerebral (brain) arteries, mesenteric (gastrointestinal), renal (kidney), and peripheral (lower extremity) arteries. Therefore, aneurysm ruptures can cause, strokes, internal bleeding, kidney failure, and limb loss.
Dissections are tears in the endothelium or media layers of the arterial wall, and blood flow can seep in between the torn layers. Driven by blood pressure, the trapped blood can cause further tears that propagate along the course of the vessel. This can lead to weakening of the arterial wall with ensuing rupture and exsanguination, or blockages of blood flow at arterial branching points. Like aneurysms, acute arterial dissections can lead to massive bleeding, strokes, heart attacks, organ failure, or limb loss if not treated in a timely fashion. Aortic dissections are surgical emergencies.
Thrombosis occurs when liquid flowing blood within arteries and veins clots off, and flow ceases. This can occur at sites where the vessel is diseased (e.g., atherosclerosis and plaque rupture, severe critical narrowing). Thrombus (clots) can originate from a remote site such as the chambers of the heart (e.g., abnormal heart rhythm – atrial fibrillation, or valvular heart disease) and embolize into an artery that then gets blocked, cutting off blood supply distally. Diseased arterial plaques can cause thromboembolism of small clots into smaller distal branches, similarly cutting off the blood to vital organs, e.g., carotid artery disease and stroke.
Venous thromboembolism (VTE) occurs on the side of the circulation where blood returns from all parts of the body to the heart. Patients can develop deep vein clots (deep vein thrombosis/DVT) in their lower extremities and if the clot breaks off, it will embolize towards the right heart circulation where blood is normally pumped to the lungs for gas exchange. This is called pulmonary embolus (PE) that can cause chest pain, shortness of breath, and coughing up of blood (hemoptysis). DVT and PE are medical emergencies that warrant expedient treatment with blood thinners to prevent more clots from forming. If large clots form, massive PEs can cause cardiac arrest and sudden death.
Doctors at PanAsia Surgery are available to help care for patients with atherosclerosis and other vascular diseases. Along with counseling for lifestyle modifications such as healthy diet, regular exercise, maintaining appropriate body-mass-index/BMI, smoking cessation and good diabetes control, our vascular specialists can offer expert vascular or endovascular (minimally invasive) interventions for specific treatments.
