12.2: Cardiovascular Diseases

The cardiovascular system is an intricate system and each part of the system plays an important role in ensuring your body receives the oxygen and nutrients it needs. Diseases of the cardiovascular includes diseases effecting the various elements of the heart and diseases impacting the ability of blood to move through the blood vessels.

The term “heart disease” refers to several types of heart conditions. The most common type of heart disease in the United States is coronary artery disease (CAD). The coronary artery is the artery that feeds oxygenated blood to the heart muscle itself. If the coronary artery is partially or fully blocked it affects the blood flow to the heart. When the heart muscle does not get oxygenated blood this is called a heart attack.

Sometimes heart disease may be “silent” and not diagnosed until a person experiences signs or symptoms of a heart attack, heart failure, or an arrhythmia. When these events happen, symptoms may include:

• Heart attack: Chest pain or discomfort, upper back or neck pain, indigestion, heartburn, nausea or vomiting, extreme fatigue, upper body discomfort, dizziness, and shortness of breath.
• Arrhythmia: Fluttering feelings in the chest (palpitations).
• Heart failure: Shortness of breath, fatigue, or swelling of the feet, ankles, legs, abdomen, or neck veins.

The risk factors for the majority of cardiovascular diseases are high blood pressure, high blood cholesterol, and smoking. About half of people in the United States (47%) have at least one of these three risk factors. Several other medical conditions and lifestyle choices can also put people at a higher risk for heart disease, including:

• Diabetes
• Overweight and obesity
• Unhealthy diet
• Physical inactivity
• Excessive alcohol use

Coronary Artery Disease

Coronary artery disease (CAD) is the leading cause of death worldwide and the most common type of heart disease in the United States. It is sometimes called coronary heart disease or ischemic heart disease. CAD is caused by plaque buildup in the walls of the arteries that supply blood to the heart and other parts of the body, this build up is called Atherosclerosis. As the coronary blood vessels become occluded, the flow of blood to the tissues will be restricted, a condition called ischemia that causes the cells to receive insufficient amounts of oxygen, called hypoxia. Angina, or chest pain and discomfort, is the most common symptom of CAD. Although angina is the most common symptom of CAD, for some people, the first sign of CAD is when they have a heart attack.

Over time, CAD can weaken the heart muscle. This may lead to heart failure, a serious condition where the heart can’t pump blood the way it should.

Arteriosclerosis and Atherosclerosis

Both atherosclerosis and arteriosclerosis negatively impact the ability of blood to flow freely throughout the body. Arteriosclerosis is known as the hardening of the artery and atherosclerosis is known as the thickening of the artery. Aging is a common factor in the hardening of the artery where the artery is losing elasticity and flexibility over time, however, lifestyle choices are a common factor in the thickening of the artery where plaques are building up in the artery.

Atherosclerosis is caused by an accumulation of plaque deposits of cholesterol and other substances in the artery. Plaque buildup causes the inside of the arteries to narrow over time, which can partially or totally block the blood flow. Atherosclerosis progresses slowly and often beginning in childhood and gradually progressing throughout life.

Well-documented risk factors include smoking, family history, hypertension, obesity, diabetes, high alcohol consumption, lack of exercise, stress, and hyperlipidemia or high circulating levels of lipids in the blood.

Figure \(\PageIndex{7}\): Atherosclerosis

Have you ever used a plunger

Take a moment to think about how the plumbing in a house or building works. When it works well, water comes into the house freely and waste from flushing the toilet or washing dishes flows out of the house. However, if the plumbing of a house get blocked by debris, then a backup occurs. Just like in a house, debris that blocks flow causes problems.

Angina

Angina, or chest pain and discomfort, is the most common symptom of CAD. Angina can happen when too much plaque builds up inside arteries, causing them to narrow. Narrowed arteries can cause chest pain because they can block blood flow to your heart muscle and the rest of your body.

Myocardial Infarction or “heart attack”

Myocardial infarction (MI) is the formal term for what is commonly referred to as a heart attack. It normally results from a lack of blood flow (ischemia) and oxygen (hypoxia) to a region of the heart, resulting in death of the cardiac muscle cells. An MI often occurs when a coronary artery is blocked by the buildup of atherosclerotic plaque. It can also occur when a portion of an unstable atherosclerotic plaque travels through the coronary arterial system and lodges in one of the smaller vessels. The resulting blockage restricts the flow of blood and oxygen to the myocardium and causes death of the tissue. MIs may be triggered by excessive exercise, in which the partially occluded artery is no longer able to pump sufficient quantities of blood, or severe stress, which may induce spasm of the smooth muscle in the walls of the vessel.

For many people, the first clue that they have CAD is a heart attack. Symptoms of heart attack include

• Chest pain or discomfort (angina)
• Weakness, light-headedness, nausea (feeling sick to your stomach), or a cold sweat
• Pain or discomfort in the arms or shoulder
• Shortness of breath

MIs may trigger cardiac arrest, but the two are not synonymous.

Cardiac Arrest and Arrhythmia

Cardiac arrest occurs when the heart suddenly and unexpectedly stops pumping. If this happens, blood stops flowing to the brain and other vital organs. The main cause of cardiac arrest is having an arrhythmia. An arrhythmia, or irregular heartbeat, is a problem with the rate or rhythm of your heartbeat. When a person suffers from cardiac arrest, there are a number of things that could potentially be happening to their heart: they could have a rapid heart rhythm (tachycardia), a disorganized electrical rhythm that doesn’t allow heart muscles to contract (fibrillation), or they could have no electrical current passing through their heart (asystole).

Nine out of 10 people who have a cardiac arrest outside of a hospital die — often within minutes.

Important risk factors include prior cardiac arrest, coronary heart disease, heart valve disease, congenital heart defects, and arrhythmias caused by faulty gene. However, half of cardiac arrests happen to people who did not know they had a heart problem.

"Clear"

Have you watched medical shows where a doctor grabs paddles, rubs them together, yells “clear,” and then shocks or zaps the patient? They are using a machine called a defibrillator that sends an electrical shock to the heart to try to get the electrical signals in the heart to contract in their regular rhythm. Although you might believe the defibrillator is restarting the heart, it is actually stopping the heart in order to try to get the hearts electrical signal to reset and resumes beating in a normal rhythmic way.

Congenital Heart Defects

Congenital heart defects are problems with the heart that are present at birth. They are the most common type of major birth defect. Examples include abnormal heart valves or holes in the heart’s walls that divide the heart’s chambers. Congenital heart defects range from minor to severe.

Heart Valve Defects

Heart valves prevent the backward flow of blood. They are located between the chambers of the heart and where the blood leaves and returns to the heart. Healthy heart valves can fully open and close the valve during the heartbeat, but diseased valves might not fully open and close. If the heart valves are diseased, the heart can’t effectively pump blood throughout the body and must work harder to pump, either while the blood is leaking back into the chamber or against a narrowed opening. This can lead to heart failure, sudden cardiac arrest (when the heart stops beating), heart palpitations (rapid, fluttering, or pounding), shortness of breath, or swelling in your legs and feet.

Valvular disorders are often caused by carditis, or inflammation of the heart. One common trigger for this inflammation is rheumatic fever, or scarlet fever, an autoimmune response to the presence of a bacterium, Streptococcus pyogenes, normally a disease of childhood.

Congestive Heart Failure

Heart failure is often called congestive heart failure because of fluid buildup in the lungs, liver, legs, and feet. Heart failure is a serious condition that occurs when the heart can’t pump enough blood to meet the body’s needs. It does not mean that the heart has stopped but that muscle is too weak to pump enough blood. Most of heart failure cases are chronic, or long-term heart failures.

The only cure for heart failure is a heart transplant. However, heart failure can be managed with medications or medical procedures.

Stroke or “brain attack”

A stroke is sometimes called a “brain attack” and is formally known as a Cerebrovascular Accident (CVA). Like a heart attack, a brain attack (stroke) occurs because oxygen cannot get to the brain. With a stroke, the oxygen may not be getting to the brain because of a blockage in the blood vessel (likely due to atherosclerosis) or due to a rupture of the blood vessel. In either case, parts of the brain become damaged or die. To work properly, your brain needs oxygen. Your arteries deliver oxygen-rich blood to all parts of your brain. If something happens to block the flow of blood, brain cells start to die within minutes, because they can’t get oxygen. This causes a stroke.

Time lost is brain lost. Every minute counts.

The brain controls our movements, stores our memories, and is the source of our thoughts, emotions, and language. The brain also controls many functions of the body, like breathing and digestion. The impact of a stroke is dependent on the part of the brain that is not getting the oxygen it needs. A stroke can cause lasting brain damage, long-term disability, or even death.

There are two types of stroke:

• Ischemic stroke
  • Most strokes are ischemic strokes. An ischemic stroke occurs when blood clots or other particles block the blood vessels to the brain. Fatty deposits called plaque can also cause blockages by building up in the blood vessels.
• Hemorrhagic stroke
  • A hemorrhagic stroke happens when an artery in the brain leaks blood or ruptures (breaks open). The leaked blood puts too much pressure on brain cells, which damages them. High blood pressure and aneurysms are examples of conditions that can cause a hemorrhagic stroke. Aneurysms are balloon-like bulges in an artery that can cause the artery to stretch and burst.

Figure \(\PageIndex{8}\): Ischemic Stroke

Figure \(\PageIndex{9}\): Hemorrhagic Stroke

A transient ischemic attack (TIA) is sometimes called a “mini-stroke” or a “warning stroke.” It is different from the major types of stroke, because blood flow to the brain is blocked for only a short time—usually no more than 5 minutes.

• A TIA is a warning sign of a future stroke.
• A TIA is a medical emergency, just like a major stroke.
• Strokes and TIAs require emergency care. Call 9-1-1 right away if you feel signs of a stroke or see symptoms in someone around you.
• There is no way to know in the beginning whether symptoms are from a TIA or from a major type of stroke.
• Like ischemic strokes, blood clots often cause TIAs.
• More than a third of people who have a TIA and don’t get treatment have a major stroke within 1 year. As many as 10% to 15% of people will have a major stroke within 3 months of a TIA.