Coronary Artery Disease
CORONARY ARTERY DISEASE
CORONARY ARTERY DISEASE DEFINITION
Coronary artery disease (CAD) is one of the common vascular diseases marked by accumulation of atherosclerotic plaque in the coronary blood vessels. As the plaque thickens, secondary changes may take place like enlargement of size and calcification that may lead to complete occlusion of lumen of the coronary artery, resulting in inadequate supply of oxygen to the heart muscle.
CORONARY ARTERY DISEASE CAUSES
Research suggests that coronary heart disease (CHD) starts when certain factors damage the inner layers of the coronary arteries. These factors include:
- High levels of certain fats and cholesterol in the blood
- High blood pressure
- High levels of sugar in the blood due to insulin resistance or diabetes
- Blood vessel inflammation
Plaque might begin to build up where the arteries are damaged. The buildup of plaque in the coronary arteries may start in childhood.
Over time, plaque can harden or rupture (break open). Hardened plaque narrows the coronary arteries and reduces the flow of oxygen-rich blood to the heart. This can cause angina (chest pain or discomfort).
If the plaque ruptures, blood cell fragments called platelets (PLATE-lets) stick to the site of the injury. They may clump together to form blood clots.
Blood clots can further narrow the coronary arteries and worsen angina. If a clot becomes large enough, it can mostly or completely block a coronary artery and cause a heart attack.
CORONARY ARTERY DISEASE PATHOPHYSIOLOGY
When the arterial endothelium encounters certain bacterial products or risk factors as diverse as dyslipidemia, vasoconstrictor hormones inculpated in hypertension, the products of glycoxidation associated with hyperglycemia, or proinflammatory cytokines derived from excess adipose tissue, these cells augment the expression of adhesion molecules that promote the sticking of blood leukocytes to the inner surface of the arterial wall. Transmigration of the adherent leukocytes depends in large part on the expression of chemoattractant cytokines regulated by signals associated with traditional and emerging risk factors for atherosclerosis. Once resident in the arterial intima, the blood leukocytes—mainly mononuclear phagocytes and T lymphocytes—communicate with endothelial and smooth muscle cells (SMCs), the endogenous cells of the arterial wall. Major messages exchanged among the cell types involved in atherogenesis depend on mediators of inflammation and immunity, including small molecules that include lipid mediators such as prostanoids and other derivatives of arachidonic acid, eg, the leukotrienes. Other autacoids, such as histamine, classically regulate vascular tone and increase vascular permeability. Recently, much attention has focused on protein mediators of inflammation and immunity, including the cytokines and complement components. Virtually unknown by cardiologists a mere decade ago, the cytokines have joined the mainstream of our specialty.
CORONARY ARTERY DISEASE SYMPTOMS
The most common symptom of coronary artery disease is angina (also called angina pectoris). Angina is often referred to as chest pain. It is also described as chest discomfort, heaviness, tightness, pressure, aching, burning, numbness, fullness, or squeezing. It can be mistaken for indigestion or heartburn. Angina is usually felt in the chest, but may also be felt in the left shoulder, arms, neck, back or jaw.
- Pain or discomfort in other areas of the upper body including the arms, left shoulder, back, neck, jaw, or stomach
- Difficulty breathing or shortness of breath
- Sweating or “cold sweat”
- Fullness, indigestion, or choking feeling (may feel like “heartburn”)
- Nausea or vomiting
- Light-headedness, dizziness, extreme weakness or anxiety
- Rapid or irregular heart beats
CORONARY ARTERY DISEASE DIAGNOSIS
- Physical Exam: During a physical exam, your health professional may use a stethoscope to check your arteries for an abnormal whooshing sound called a bruit, which may indicate poor blood flow due to plaque buildup. He or she also may check to see whether any of your pulses (for example, in the leg or foot) are weak or absent, which can be a sign of a blocked artery.
- Diagnostic Tests: Your healthcare provider may recommend one or more tests to diagnose atherosclerosis. These tests can help define the extent of your disease and the best treatment plan.
o Blood Tests check the levels of certain fats, cholesterol, sugar, and proteins in your blood. Abnormal levels may put you at risk for atherosclerosis.
o Ankle/Brachial Index compares the blood pressure in your ankle with the blood pressure in your arm to see how well your blood is flowing. Used to help diagnose P.A.D.
o EKG (Electrocardiogram) detects and records the heart’s electrical activity. It shows how fast the heart is beating and its rhythm (steady or irregular).
o Echocardiography uses sound waves to create a moving picture of your heart. The test provides information about the size and shape of your heart, how well your heart chambers and valves are working, and areas of poor blood flow.
o Computed Tomography Scan creates computer-generated pictures and can show hardening and narrowing of large arteries.
o Stress Testing You exercise (or are given medicine if you are unable to exercise) to make your heart work hard and beat fast while heart tests are done. A stress test can show possible signs of CAD.
o Angiography: Angiography uses dye and special X-rays to reveal the insides of your arteries. It can show whether plaque is blocking your arteries and how severe the blockage is.
CORONARY ARTERY DISEASE TREATMENT
When atherosclerosis is identified at an early stage, medications such as nitrates, beta blockers, calcium channel blockers, aspirin, or cholesterol-lowering drugs (statins) may be prescribed. These medicines may slow the disease’s progress or ease its symptoms.
Coronary artery bypass grafting, or “CABG” (pronounced “cabbage”), is a common heart procedure. A surgeon takes a section of a healthy blood vessel from your leg, chest, or arm. The vessel is then connected (grafted) to your coronary artery slightly past the site of the blockage. This creates a new path for blood to flow around (bypass) the blockage in the artery so it can get to your heart.
Patients undergoing bypass are put under general anaesthetic and are not awake during surgery. Two bypass surgical procedures for coronary artery disease are: (1) beating heart surgery and (2) arrested heart surgery.
- Beating heart surgery – Also known as off-pump surgery, beating heart surgery is done while the heart is beating. This often requires special equipment that allows the surgeon to operate on the heart while it is moving. Beating heart surgery is appropriate for certain patients.
- Arrested heart surgery – Most CABG surgeries are done through an incision in the chest while the heart is stopped and a heart-lung machine takes over the job of circulating the blood. This is called arrested heart surgery or conventional bypass surgery.
Minimally Invasive Treatments
For some patients, minimally invasive coronary artery surgery is an alternative to the CABG surgery. Three minimally invasive treatments for coronary artery disease (CAD) are coronary balloon angioplasty, stenting, and minimally invasive cardiac surgery (MICS) CABG.
- Coronary balloon angioplasty – Coronary balloon angioplasty, also referred to as percutaneous (through the skin) coronary intervention (PCI), uses a tiny balloon to widen the inside channel of the artery and enable blood to flow at a normal or near-normal rate.
- Stenting – Stenting uses a device called a stent to restore blood flow in the coronary artery. A stent is a tiny, expandable, mesh-like tube made of a metal such as stainless steel or cobalt alloy. Like in an angioplasty procedure, a stent mounted onto a tiny balloon is opened inside of an artery to push back plaque and to restore blood flow.
- MICS CABG – The beating heart procedure described above can be performed through a small rib incision rather than through a median sternotomy.