Module 3: The Cardiovascular System

Transcription

1 Module 3: The Cardiovascular System Module Aim This module is an overall introduction to the cardiovascular system, its components, and their functions and some related diseases. This will help you understand underlying causes of risk factors outlined in Module 4 that lead to cardiovascular diseases. This module is important to understand, as further modules will build on this basic knowledge. This module contains the following sections: Section 3.1: Structure and Function of the Cardiovascular System Section 3.2: Diseases of the Cardiovascular System Section 3.3: Burden of Cardiovascular Disease Final September-17 Page 1 of 20

2 Contents Module Aim... 1 Module 3 Pre-test... 3 Section 3.1: Structure and Function of the Cardiovascular System Introduction to the Cardiovascular System Blood... 5 I. Red blood cells (RBCs)... 5 II. White blood cells (WBCs)... 5 III. Platelets... 6 IV. Plasma... 6 Functions of Blood Heart... 7 Chambers and Valves... 7 Flow of Blood... 8 Beating of the Heart... 8 The Cardiac Cycle Blood Vessels... 9 I. Arteries II. Capillaries III. Veins Section 3.2: Diseases of the Cardiovascular System Heart Attack, Angina, and CHD Stroke Peripheral Vascular Disease Congestive Heart Failure (CHF) Section 3.3: Burden of Cardiovascular Disease Socio-Economic Burden Module 3 Post-Test Final September-17 Page 2 of 20

3 Module 3 Pre-test Instructions: Read the following statements carefully and tick [ ] the appropriate column. If you are unsure of any answer you may tick the Don t Know column. The time allotted to you is 5 minutes. Number Question True False Don t Know 1 Blood delivers oxygen throughout the body. 2 The heart normally contains 5 chambers. 3 4 Blood pressure is created by the lungs putting pressure on blood vessels. A heart attack is caused by a clot in the blood vessels of the heart. 5 A stroke occurs when the brain is deprived of oxygen. 6 7 Congestive heart failure means the heart stops beating. Cardiovascular disease primarily affects higher income countries and groups. Final September-17 Page 3 of 20

4 Section 3.1: Structure and Function of the Cardiovascular System In this section, you will learn about the structure of different parts of the cardiovascular system (CVS) as well as their functions. It is important to have a clear idea of the CVS structures and functions discussed in this section in order to understand the ways cardiovascular diseases can occur, which are discussed in the next sections. This section will also help you understand the CVS, so if/when a participant or their treatment supporter has questions, you will be able to discuss the participant s CV conditions. The body is made up of a number of systems that control different functions, such as the respiratory system for breathing, the digestive system that helps us break down the foods we eat, and the nervous system that allows us to think and react to the environment around us. In the HOPE-4 program, we are interested in the CVS the system responsible for supplying blood to all parts of our bodies. It is an essential system for survival, and in this module we will look at the parts of this system and why we need to keep it healthy. Learning objectives at the end of this section you should be able to: List the key components of the CVS List the components and function of blood Understand the flow of blood and chambers in the heart Explain the types of blood vessels and flow of blood throughout the body Describe blood pressure and its importance This section contains the following subsections: Introduction to the Cardiovascular System Blood Heart Blood Vessels Introduction to the Cardiovascular System All the organs and tissues in the body require oxygen. This requirement is fulfilled by the constant flow of oxygen-carrying blood. The CVS is responsible for making sure the flow of blood is constant, allowing every cell in the body to have access to oxygen. Without a properly functioning CVS, our cells would be unable to function properly. The CVS has a number of parts that control the flow of blood. These components are: Blood Heart Blood vessels Final September-17 Page 4 of 20

5 The main function of the CVS is to pump blood throughout the body. The function of the heart is to act as the pump, pushing blood into the blood vessels. The blood vessels carry blood to all the different parts of the body, before it is returned back to the heart to start the cycle again. Blood carries oxygen from the lungs throughout the body. It is also responsible for transporting waste products such as carbon dioxide, which are then eliminated by other bodily systems. Remember: The major components of the cardiovascular system are: - Blood - Heart - Blood vessels The main purpose of the cardiovascular system is to pump nutrient-rich and oxygen-rich blood to all parts of the body Blood Blood is a fluid that delivers necessary substances, including nutrients and oxygen, to all different parts and cells of the body. Blood also carries waste products away from the cells to other areas where they can be processed. The average adult has around 5 liters of blood. Blood is mainly composed of solid blood cells, which are suspended in the liquid plasma. The plasma consists of approximately 90% water, with the rest being made up of other dissolved substances (e.g. clotting proteins, sugars, hormones, and minerals). There are four main components of blood (Figure 1): I. Red blood cells II. White blood cells III. Platelets IV. Plasma I. Red blood cells (RBCs) These are the most common cells in the blood. These cells contain a special protein called hemoglobin that allows them to transport oxygen and carbon dioxide within the blood stream. This function makes these cells extremely important. II. White blood cells (WBCs) These cells are part of the immune system, acting to defend the body from infectious diseases or intruding cells. They destroy and remove old cells and debris from the blood, while also attacking foreign disease-causing agents and foreign substances in the body. Final September-17 Page 5 of 20

6 III. Platelets These cells are responsible for the clotting of blood, also referred to as coagulation. When the skin is cut, these cells create a mesh-like barrier over the cut. Other blood cells become caught in the mesh and collect to form a clot, which stops blood from leaving the body and prevents bacteria from entering the bloodstream. Platelets are very important in tissue healing. IV. Plasma Plasma is the liquid component of blood that the cells are suspended in. It accounts for around 50% of the total volume of blood and contains things like dissolved proteins, glucose, and platelets, as well as the blood cells themselves. Blood Cells WBCs RBCs Plasma Platelets Blood Figure 1. The components of blood Functions of Blood Blood is a vital fluid in our bodies and performs many important functions. Some of these functions include: Supplying oxygen to tissues (carried by RBCs) Supplying nutrients from food to cells around the body Removal of waste, including carbon dioxide Defense against diseases and detection of foreign material (by WBCs) Clotting and prevention of blood loss (platelets and clotting proteins) Messenger functions by transporting hormones to various systems, allowing them to interact (e.g. insulin is created by the digestive system and circulated through the blood, allowing cells to absorb sugars from food we eat) Helping regulate and maintain body temperature Final September-17 Page 6 of 20

7 Activity: Matching Match the listed components with their functions. I. Responsible for blood clotting A. Red blood cells II. Contain hemoglobin responsible for carrying oxygen B. Plasma III. Destroy and remove old cells and foreign substances C. White blood cells IV. Liquid part of blood containing 90% water D. Platelets Heart The heart pumps blood in order for it to circulate throughout the body. The heart is a very strong muscle that is able to contract and relax rhythmically throughout a person s lifetime. Each day, the heart will beat an average of 100,000 times, pumping over 7,500 liters of blood. The heart is located in the left side of the chest, in a cavity between the right and left lungs. It weighs between 200 and 425 grams (around the weight of a can of pop), and is a little larger than an individual s clenched fist. Because the heart is a large, constantly active muscle, it must also have its own constant supply of oxygen, allowing it to continue pumping. Chambers and Valves The human heart has four chambers, each separated by a valve (Figure 2). The four chambers include the right atrium, right ventricle, left atrium, and left ventricle. When you are looking at the diagram below, it is important to note that the left and right are reversed. Imagine they are the left and right side of your body as you would see them. It is the relaxation and contraction of these chambers that allows the heart to pump blood. The valves that separate the four chambers prevent blood from flowing backwards, thus only allowing the flow of blood in one direction. Genetic defects or illness-related damage in the heart chambers or valves disrupt the flow of blood, which may be contributing factors to the development and severity of cardiovascular diseases. Aorta Right Atrium Left Atrium Right Ventricle Left Ventricle Figure 2. The heart with the four chambers and aorta Final September-17 Page 7 of 20

8 Flow of Blood The heart is made up of large muscles that cause the contraction and relaxation of the heart, and when these muscles take turns contracting, blood is passed through the valves separating the chambers, from one chamber into another. The two right chambers (the right atrium and right ventricle) are responsible for pumping blood to the lungs. When this blood passes by the lungs, it collects oxygen (enters the body during inhalation), and drops off carbon dioxide (exits the body during exhalation). The freshly oxygenated blood returns to the left side of the heart (left atrium and left ventricle), from which it is pumped into the aorta. The aorta splits into the other blood vessels of the body and distributes the oxygenated blood. When the oxygen is used by cells, they replace it with carbon dioxide. The blood collects through the blood vessels and returns to the right side of the heart. From here, the cycle is repeated, with the right side of the heart pumping the deoxygenated blood to the lungs where it becomes oxygenated. Beating of the Heart We know that it is the contraction of the heart that pumps blood throughout the body, but what is it that causes these contractions to happen? The heartbeat is created by small electrical impulses that perpetually cause the muscles in the heart to contract. A network of nerve fibers is present between the muscles in the heart, and these fibers act like electrical wires, coordinating the contraction and relaxation of the different chambers. By keeping all of these muscles contracting and relaxing in a coordinated way, the heart creates a wave-like pumping action that efficiently moves blood throughout the body. The steady pumping action of the heart is often described as its rhythm. It is normal for the heart to beat at different rates throughout the day. People may occasionally experience harmless variations in heart rhythm, referred to as palpitations. To contrast, a consistently abnormal heart rhythm is referred to as an arrhythmia. The heart may beat too fast, too slow, or with an irregular pattern. Changes to heart rhythm are caused by irregularities in the transmission of the electrical impulses that cause the heart muscles to contract. An arryhthmia does not necessarily mean that the heart is unhealthy, but some types of arrhythmias are of concern. Syncope (fainting) is associated with some arrhythmias. Arrhythmias must be diagnosed by a physician, often using an electrocardiogram (ECG) or other heart monitoring device. The most common arrhythmia is atrial fibrillation, which is characterized by a rapid, irregular heart beat. Atrial fibrillation is caused by abnormal electrical impulses in the upper chambers of the heart (left atrium and right atrium). These abnormal electrical impulses cause the upper chambers to contract very rapidly and irregularly, in comparison to the lower chambers of the heart (left and right ventricles). The pumping action of the heart is therefore uncoordinated, so the heart does not pump blood as efficiently. Atrial fibrillation decreases the heart s pumping efficiency and increases the risk of blood clot formation in the heart and the arteries. These effects can increase a person s risk of congestive heart failure, heart attack, and stroke, which you will discuss in section 3.2. Final September-17 Page 8 of 20

9 The Cardiac Cycle The cardiac cycle is the sequence of events that occurs when the heart beats. There are two phases of this cycle: I. Systole (contraction) II. Diastole (relaxation) I. Systole Systole is the phase in which both ventricles contract. When these two chambers contract, the muscles powerfully push the blood out into the blood vessels moving away from the heart. As noted before, the right ventricle pushes blood to the lungs, while the left ventricle pushes blood into the aorta, before it is distributed to the rest of the body. During this phase, the contractions cause an increase in the pressure within the blood vessels. II. Diastole Diastole is the phase in which both ventricles are relaxed. When these two chambers are relaxed, they are refilled with blood from the each atrium, getting new blood to pump out from the heart and into the blood vessels when the cycle begins again. During this phase, no new blood is pumped into the blood vessels, and thus the pressure in the blood vessels is lower than it is during systole. The cycle of systole and diastole phases continues repeating and is called the cardiac cycle. A normal human heart beats around times per minute when at rest. Remember: It is the contraction and relaxation of the heart that pushes blood through the blood vessels. Systole is when the heart is contracting (higher pressure). Diastole is when the heart is relaxed (lower pressure) Blood Vessels The blood vessels are the part of the CVS that carry blood throughout the different parts of the body. These vessels carry blood into all of our organs and tissues, supplying the oxygen and nutrients necessary for our bodies to function properly. There are 3 major types of blood vessels: I. Arteries carry blood (rich in oxygen) away from the heart to the body II. Capillaries very small blood vessels that allow for exchange of gases (oxygen and carbon dioxide), water, nutrients, and waste products to and from the blood III. Veins carry blood (poor in oxygen) back to the heart Final September-17 Page 9 of 20

10 I. Arteries Arteries are the blood vessels that carry blood away from the heart. The walls of these vessels are elastic in nature, which allows them to expand and contract as the heart powerfully pumps blood through them. The size of these vessels decreases as they move further and further away from the heart, until they become the smallest vessels capillaries. The heart has its own set of arteries to supply it with blood called the coronary arteries. These will be further discussed in section 3.2. The powerful pumping of the heart exerts pressure on the walls of the arteries as blood flows through them, causing them to expand. This rhythmic expansion and contraction of the blood vessels can be felt as the pulse (or heart rate), and it can be measured as blood pressure (BP). We will discuss these further in Module 4 and Module 5. It is important to remember, however, that the force of the blood on the blood vessels is what creates BP. II. Capillaries As the arteries become smaller and smaller, they eventually turn into capillaries very thin blood vessels. These vessels are thin enough to allow the products carried within the blood to be exchanged with the surrounding tissues. These include nutrients derived from food, oxygen, carbon dioxide, and waste products. As waste products and carbon dioxide collect in the capillaries, many capillaries come together and form larger vessels to transport the blood back to the heart these larger vessels are the veins. III. Veins Veins collect blood from the capillaries and return it to the heart. Since they are farther away from the heart, the BP in these vessels is much lower compared to arteries. The veins all carry low oxygen (poor in oxygen) blood back to the heart, where the cycle can repeat itself. Remember: There are three major types of blood vessels: I. Arteries II. Capillaries III. Veins It is important to note that the two most important organs of the body the heart and the brain have networks of blood vessels that ensure they are constantly supplied with blood. A constant supply to these organs is crucial for our well-being, and problems with circulation to these organs can cause serious problems, as will be discussed in the next section. Discussion Questions What are the main functions of blood, and what might happen if one of these functions were to be disabled? Final September-17 Page 10 of 20

11 During systole is the heart contracting or relaxing? Does the BP increase or decrease during this phase? How about for diastole? If a blood vessel becomes blocked, what might happen? Section 3.2: Diseases of the Cardiovascular System Now that you have an understanding of the structure and normal function of the CVS, we will look at some important diseases that occur as a result of issues that affect the CVS. Disturbances to any part of the CVS, including conditions discussed in the previous section, such as heart chamber or valve defects and arrhythmias like atrial fibrillation, can contribute to the development and severity of diseases that ultimately prevent the blood from adequately circulating to all parts of the body. Cardiovascular Disease (CVD) includes a group of disorders of the heart and blood vessels, including: Coronary heart disease (CHD) (heart attack, angina, congestive heart failure) Cerebrovascular disease (stroke) Peripheral vascular disease (poor blood supply to limbs) Rheumatic heart disease (heart damage from bacterial infection) Congenital heart disease (heart defect present at birth) Deep vein thrombosis and pulmonary embolism (blockages of blood flow due to blood clots) CHD and cerebrovascular disease (stroke) account for the majority of cases of CVD. CHD includes heart attacks, angina, and congestive heart failure. Learning objectives at the end of this section, you should be able to: Identify and describe significant CVD Understand the conditions that lead to these diseases List the parts of the CVS that are affected by these diseases This section contains the following subsections: Heart Attack, Angina, and CHD Stroke Peripheral Vascular Disease Congestive Heart Failure Final September-17 Page 11 of 20

12 Heart Attack, Angina, and CHD The heart requires a constant supply of oxygenated blood. As mentioned previously, the heart has its own blood supply, which is critical to its function. When the muscle cells in the heart do not receive adequate oxygen, they die. A blocked artery within the heart is the usual cause of insufficient oxygen for heart function. How is this caused? First, we must understand atherosclerosis (blockages in the arteries due to plaque build-up). Previously, arteries were described as elastic vessels that expand and contract with each beat of the heart. As a person ages, these arteries lose their elasticity and can get harder and thicker. This thickening and hardening is due to the deposition of plaque on the internal lining of the arteries. Plaque typically contains cholesterol (fatty substance), waste products from cells, and calcium. As this plaque deposits itself on the normally smooth lining of the arteries, it reduces the amount of space through which blood can flow (Figure 3). Plaques can rupture or crack, which can cause the sudden formation of a blood clot. Figure 3. The effects of atherosclerosis on blood vessels Normal Blood Flow Plaque narrows artery; Obstacle to blood flow Normal Artery Atherosclerosis Artery Pressure is exerted onto the walls of blood vessels as blood flow through them, so blood vessel walls must be strong to contain the blood. The hardening of blood vessels from plaque build-up can weaken the walls of blood vessels. Narrowing of the arteries due to atherosclerosis, and high blood pressure, put additional pressure on blood vessels, particularly where they branch. A weakened blood vessel can develop an outward bulge, referred to as an aneurysm. Rupture of an aneurysm can lead to internal bleeding and may be life-threatening if undetected. Since the heart is essentially a large muscle that is constantly contracting and relaxing, it requires its own blood supply to provide it with sufficient oxygen. This blood is supplied through a specific group of arteries known as the coronary arteries. When atherosclerosis occurs within the coronary arteries, it can lead to decreased blood supply to those areas of the heart that are affected. Without sufficient blood flow in the coronary arteries, the heart becomes fatigued from a lack of nutrients and oxygen. The restriction of blood flow to vessels in the heart is called coronary heart disease (CHD) (Figure 4). Final September-17 Page 12 of 20

13 Figure 4. The effects of atherosclerosis on arteries in the heart cause CHD Angina (chest pain) is a result of partial blockages of coronary arteries due to CHD. To treat CHD, a hospital procedure is generally required and can be either surgical or non-surgical. The non-surgical intervention is called angioplasty, which is a medical term to describe the procedure in which narrow coronary arteries are widened using a tiny balloon that is inflated to widen the artery. A stent is often put in place after the artery is widened. It is essentially a tube that is placed in the narrowed coronary artery that allows blood to flow through more easily (Figure 5). Balloon Figure 5. The angioplasty procedure Stent A small balloon opens up the narrowed artery and a stent is placed to reestablish proper blood flow. The surgical procedure to treat CHD is called coronary bypass surgery, wherein a narrowed coronary artery is surgically removed and the narrowed section bypassed (Figure 6). An analogy of the bypass surgery would be like building a new road around a congested highway to avoid the traffic a new coronary artery is placed around the old one so the blood can flow past it more freely. Final September-17 Page 13 of 20

14 Figure 6. Bypass surgery A bypass graft (a replacement artery) is placed to avoid blood flow through a narrowed or blocked coronary artery. Angina (chest pain) is a condition caused by decreased blood flow to areas of the heart, due to CHD (Figure 4). As previously discussed, CHD is caused by atherosclerosis, which narrows or blocks coronary arteries. Heart valve problems can also restrict blood flow in the coronary arteries and cause angina. Pain is caused by a buildup of lactic acid a waste product from heart muscles that are not getting enough oxygen. Lactic acid buildup is the same thing that causes pain in your arms or legs when exercising for a long period of time. Angina is usually treated by using drugs that that either increase the oxygen available to the heart, or reduce its demand for oxygen, allowing the reduced blood flow to provide enough oxygenated blood. Angina can be brought on by strenuous activity or exertion. The pain often goes away after less than 10 minutes rest, or when medication (e.g. nitroglycerin) is taken. Angioplasty and coronary artery bypass surgery can improve blood flow in people with angina. Worsening CHD can result in the development of a clot. Clots are formed by platelets in the blood binding together. The clot may form in an artery and completely block blood flow through that artery. A complete blockage of a coronary artery from a clot prevents heart cells from receiving an adequate amount of oxygen, causing the heart cells to function improperly and even die. When a complete blockage occurs suddenly and causes heart muscle cells to die, it is known as a heart attack. The severity of a heart attack depends on the size of the artery that is blocked by the clot (and therefore the corresponding reduction in oxygen-rich blood that reaches heart muscle cells). A heart attack causes chest pain that can extend into the shoulders, arms and jaw. It must be treated in the hospital using drugs to control pain, and to reduce or remove the clot. Bypass surgery may also be used to bypass the clot, similar to CHD and angina treatment. The risk of clot formation inside the chambers of the heart is increased if a person has atherosclerosis, due to restricted blood flow. Similarly, conditions that impair blood flow, such as heart valve defects or atrial fibrillation, further increase the risk of clot formation. Remember: Atherosclerosis is the thickening and hardening of the arteries due to buildup of plaque Thickening and partial blockage of coronary arteries is called CHD CHD can lead to angina A sudden total blockage due to a blood clot in the coronary arteries can cause a heart attack Final September-17 Page 14 of 20

15 Stroke Like the heart, the cells of the brain are extremely sensitive and require a constant flow of oxygenated blood in order to function properly. These cells cannot survive without oxygen for more than a few minutes. A lack of oxygenated blood flow to any part of the brain can result in a stroke (Figure 7). Atherosclerosis can occur in the arteries leading to the brain, just as in any other arteries. Atherosclerosis can therefore cause stroke from partial or complete blockage of arteries leading to the brain, just as partial or complete blockage of coronary arteries respectively leads to CHD and angina, or heart attack. Consequently, stroke is most commonly (80%) due to a blockage in an artery supplying blood to a part of the brain (Figure 8). As previously mentioned, arrhythmias and heart defects can also increase the risk of blood clot formation because they disrupt normal blood flow. Figure 7. Cause of stroke The most common cause of stroke is a clot or blockage of blood vessels to the brain, which deprives it of oxygen. Less commonly (20%), stroke can be caused by the rupturing of a blood vessel in the brain, which causes internal bleeding and results in inadequate blood flow to a part of the brain. Aneurysm rupture is associated with this cause of stroke, as aneurysms form where blood vessels walls are weakened and therefore more likely to rupture. Symptoms of stroke depend on which part of the brain is affected by the lack of blood flow. Most commonly, weakness occurs on one side of the body, with complete lack of movement and sensation in a leg or arm. There can be speech problems and a weakness of muscles in the face. Numbing and tingling sensations are common. Some strokes affect balance, vision, swallowing, breathing, and can lead to loss of consciousness. Final September-17 Page 15 of 20

16 Figure 8. Blood flow problems may that lead to stroke Remember: A stroke is the result of oxygen depletion in the brain and can occur due to: o A clot forming in arteries of the brain (80% of cases) o The rupturing of a blood vessel in the brain (bleeding; 20% of cases) Peripheral Vascular Disease In addition to narrowing arteries of the heart and brain, atherosclerosis can also cause a narrowing of the arteries in the legs or arms, which limits their blood supply and leads to peripheral vascular disease. After exercise, or even mild exertion such as walking, a poor blood supply to the arteries in the limbs can result in pain referred to as claudication. Like angina of the heart, the pain in the limbs is caused by lactic acid accumulation in the muscles because of poor blood flow (insufficient oxygen supply). Claudication is relieved by rest. In severe cases of peripheral vascular disease, pain is present at rest and skin ulcers may develop. Like CHD, angioplasty or arterial bypass surgery treatments are available Congestive Heart Failure (CHF) Heart failure is a condition in which the heart muscles have become very stiff and/or weak. When this occurs, the heart is unable to pump blood with as much force, and therefore the blood travels through the body at a slower rate. Due to this impeded blood flow, the pumping of sufficient oxygen and nutrients is reduced. In order to compensate for this drop, the chambers of the heart can stretch and/or thicken. While this helps to re-establish sufficient blood flow in the short-term, over time the muscles can further weaken and become increasingly unable to pump blood efficiently. Heart defects including valve problems, and arrhythmias such as atrial fibrillation, can also contribute to heart failure because they decrease the heart s pumping efficiency and affect blood flow. Final September-17 Page 16 of 20

17 The pumping action of the heart extends throughout the entire body and is responsible for pumping fluids from the extremities (like the arms and legs) back up to the heart so circulation can continue. In those with CHF, this pumping action is reduced. Lower blood flow results in the body retaining more fluids. This occurs primarily in the legs, feet, abdomen, and the lungs or other organs. This causes congestion in the body, which is why it is called congestive heart failure. CHF can be caused by a number of contributing factors. As in angina, a buildup of plaque on the arteries supplying blood to the heart can contribute to stiffening and/or weakening of the heart muscles. Also, as discussed, a heart attack in which the arteries in the heart are blocked causes muscle cells to die from a lack of oxygen. If a number of muscles cells have died, the ability of the heart to pump blood is reduced, and can result in CHF. Other impairments to the heart can also contribute to CHF, including genetic defects, infection or illness-related damage, as well as damage from lifestyle factors like drug use and excessive alcohol consumption. Symptoms of CHF include weight gain due to swelling in the ankles and legs (from fluid retention), fatigue, shortness of breath, trouble lying flat, and weakness due to decreased blood flow. An irregular heartbeat can also be caused by CHF, as the heart beats faster in an attempt to increase blood flow. A large number of medications exist to treat CHF, and severe cases can require surgery. One notable medication is called lasix (or furosemide), which is used to reduce congestion and swelling in the legs. Remember: CHF is due to stiffened and/or weakened heart muscles CHF can cause shortness of breath and swelling of the ankles and legs Discussion Questions What conditions can blocked blood vessels lead to? Why do people with congestive heart failure get swollen legs? How do arrhythmias and genetic heart defects increase risk of CVD? Final September-17 Page 17 of 20

18 Section 3.3: Burden of Cardiovascular Disease Of all annual deaths around the globe, CVDs are the number one cause, attributable to over 17 million deaths per year (Figure 9). This number is expected to approach 25 million deaths per year by CVD affects half of the world s population at some point in their lifetime. In low- and middle-income countries, CVD generally affects people earlier in life, and is becoming increasingly more common at younger ages. Figure 9. Causes of deaths globally (WHO Burden of Disease 2011) In addition to deaths, CVD contributes to significant global disability, with around 30 million people surviving a stroke or heart attack every year. CVDs have no geographic, gender, or socio-economic boundaries. CVDs spread between both rich and poor, resulting in disease in all parts of society. In fact, more than 80% of CVD occurs in low- and middle-income countries it is not just a problem for wealthy countries. As a result, there are a number of socio-economic, socio-cultural, and psychological implications. Final September-17 Page 18 of 20

19 Socio-Economic Burden CVD is a burden on social and economic interests. CVDs generally occur in a productive age group, and they often cause premature death and disability. This prevents a part of the work force from being able to produce the same level of quality and quantity of work as would otherwise be possible. CVDs also generally require hospital visits, doctor check-ups, and medications, which along with being absent from work, can cause financial strain. As discussed in Module 1, diseases have many consequences for the individuals with the disease, their families, and their communities. There are a number of direct costs that can be attributed to CVDs. These costs include things like drug costs, hospital fees, doctors and laboratory fees, etc... There are also a large number of indirect costs, which are a little harder to see but are just as important. These include things like loss of salary, personal or financial costs to family members that help take care of sick relatives, and costs of missing work. Furthermore, indirect costs can include socio-cultural costs. These can be points such as persons not wanting to socialize as much because they cannot consume alcohol, or feeling excluded from family meals if they have to watch their diet specifically. Cumulatively, these direct and indirect economic and cultural costs can lead to negative psychological effects, which may have further socio-economic and socio-cultural implications. Discussion Question What are some non-medical problems that may arise in the life of a participant that has CVD? Final September-17 Page 19 of 20

20 Module 3 Post-Test Instructions: Read the following statements carefully and tick [ ] the appropriate column. If you are unsure of any answer you may tick the Don t Know column. The time allotted to you is 5 minutes. Number Question True False Don t Know The blood has four main components: platelets, red blood cells, white blood cells, and plasma. Systole is when the heart is relaxed and diastole is when the heart is contracting. Blood pressure increases during the systolic phase and decreases during the diastolic phase. 4 A person who has angina will never have a heart attack. 5 Angina is only treated through surgery Stroke can have two different causes bleeding in the brain and a blockage of blood flow to the brain. Shortness of breath, and swelling of the ankles and legs, are common symptoms of CHF. In middle and low income countries, CVD most often affects people later in life. CHD, angina and peripheral vascular disease are caused by atherosclerosis. Atrial fibrillation and heart valve irregularities decrease the likelihood of CVD because they increase the pumping efficiency of the heart. Final September-17 Page 20 of 20