Pathophysiology: Coronary arteries are responsible for delivering oxygen to the heart. CAD occurs when plaque forms in the arteries. This plaque narrows the arterial space or the lumen. This narrowing causes blood flow to be impaired. When the blood flow is impaired oxygen delivery is inadequate. Oxygen can not supply the heart adequately. When oxygen is not sufficiently and adequately supplied to the heart tissue, ischemia occurs.
For more information, visit www.nursing.com/cornell
Get unlimited access to lessons and study tools
Hey guys! Welcome to the lesson on coronary artery disease where I will help you understand what coronary artery disease is, what the effects are, and how it is treated.
So, coronary artery disease involves the buildup of plaque in the main vessels that supply the heart. The primary causes include high blood pressure and high cholesterol. A sign of coronary artery disease is chest pain. Here is a picture that shows the buildup of plaque on the vessel wall creating a narrowed artery making it difficult to sufficiently supply oxygen to the heart resulting in heart complications such as a heart attack.
I’m going to give you an explanation of how coronary artery disease occurs using a timeline. First, the inner walls of the vessels are damaged. In this case, it is the inner walls of the vessels supplying the heart. The damage may occur from increased pressure on the walls such as in hypertension that causes injury to the vessel wall tissues.
During the second phase, the inflammation process occurs within the vessel walls. Inflammation irritates the walls making the body react by trying to heal that area. This results in swelling, thickening, and scarring of the tissue which narrows the vessel.
So the walls are damaged, the inflammation process is occuring, and plaque now begins to stick to the inner walls. The plaque in the bloodstream is made up of fat and cholesterol. Our patients may have more plaque due to unhealthy diets and low physical activity.
So, the plaque builds up and narrows the vessel openings making it hard for blood to get through to the heart muscle itself. The plaque may eventually break off, which causes the blood to begin the clotting process. The free flowing plaque and blood clots may lead to complete occlusion, cutting off oxygen perfusion to the heart muscle.
If you are trying to decide what may cause coronary artery disease, just think about what affects the vessels. Smoking raises the blood pressure, damaging the artery walls. Obesity doesn’t cause coronary artery disease itself, but the higher levels of fat in the blood and higher blood pressure that typically occurs in obese patients causes damage the vessel walls and the buildup of plaque. Diabetes causes inflammation and the slowing of the blood vessels. Hyperlipidemia means there is a high amount of lipids in the blood that may stick to the walls when damaged. Those with a family history of coronary artery disease are more likely to have it as well.
The damage, buildup of plaque, and blockage in the coronary artery supplying the heart muscle causes serious complications in the patient. If the blood flow is cut off from the heart, the heart muscle will begin to die. This is what a heart attack, or myocardial infarction is. Acute coronary syndrome consists of three different complications that may occur with coronary artery disease. STEMI stands for ST segment elevation myocardial infarction. STEMI is the most dangerous, and is known as the widowmaker because the patient is very likely go into cardiac arrest. STEMI involves a near or complete blockage of blood flow to the heart. NSTEMI stands for non ST segment elevation myocardial infarction. NSTEMI involves the partial blockage of the blood flow to the heart. Unstable angina is similar to NSTEMI in that there is a partial blockage and chest pain even while resting.
Next we will look at how the patient presents. Something to understand is that the patient may not have any symptoms until they have an MI. If they do have symptoms, they may have chest pain that can radiate to the left arm. You may notice an irregular heart beat when you listen to their heart and feel their pulses. An EKG will show if the patient has an arrhythmia. They may say they are short of breath while they are resting or getting up to perform activities. The patient with an elevated blood pressure is more likely to have coronary artery disease because that high blood pressure causes damage to the vessel walls.
If the doctor is concerned that the patient has coronary artery disease, they may order different tests. The electrocardiogram, or EKG, will show us the rate and rhythm of the heart, and we will be able to look for an ST segment elevation. Cholesterol levels may be drawn from the patient. Remember, higher cholesterol means more fat in the blood, increasing the risk for coronary artery disease. CT scans help us to visualize vessel occlusion and stenosis. Angiograms show us inside the vessels. A stress test may be done to show the heart’s response to stress during physical activity.
How do we manage coronary artery disease? There are different medications that affect the body differently to help. Cholesterol medications such as statins help to decrease the plaque in the bloodstream. Antiplatelets such as aspirin and Anticoagulants such as rivaroxaban work to decrease blood clotting. Beta blockers like metoprolol decrease the workload of the heart. Calcium channel blockers like amlodipine relax the vessels and allow blood to flow through. Nitroglycerin opens the arteries and allows blood through, decreasing chest pain.
There are different procedures that the doctor may order to help treat the patient with coronary artery disease. An angioplasty is where a doctor goes in through a vessel in the leg or arm and all the way up to the coronary arteries to open up the vessels. Stent placement occurs during or right after the angioplasty where a metal mesh is placed to keep the vessel open. Coronary artery bypass surgery creates a new vessel pathway around the blockage. For more information about these interventions, please check out the lesson titled MI surgical intervention.
It is important to educate our patients to quit smoking, stay active, eat healthy, and control stress. We should emphasize the importance of managing diabetes to avoid the complications that come with coronary artery disease.
The primary nursing concepts for a patient with coronary artery disease are clotting, perfusion, and EKG rhythms.
Here are some key points that I want you to remember. First, coronary artery disease involves major vessel damage. Inflammation occurs, and plaque builds up on the walls creating a blockage. Second, coronary artery disease results in acute coronary syndrome as STEMI, NSTEMI, or Unstable angina. There may be no symptoms until the patient has an MI. Chest pain, arrhythmias, high blood pressure, and shortness of breath are all different symptoms associated with coronary artery disease. The patient may be diagnosed using EKG, cholesterol levels, a CT scan, an angiogram, and a stress test. Treatment for coronary artery disease includes medications such as vasodilators, cholesterol meds, and anticoagulants, and procedures such as angioplasty and coronary bypass surgery.
I’m so glad you came here to learn about coronary artery disease. Check out the lessons on Coronary Circulation, Myocardial Infarction, High Blood Pressure, and Cholesterol for further details on those subjects. Now go out and be your best self today, and as always, happy nursing.