Electrocardiography for Healthcare Professionals

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Learning Outcomes 2.1 Describe circulation as it relates to the ECG. 2.2 Recall the structures of the heart. 2.3 Differentiate between the pulmonary, systemic and coronary circulation. 2.4 Explain the cardiac cycle, and relate the difference between systole and diastole.

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<p>Electrocardiography for Healthcare Professionals<br>Chapter 2: The Cardiovascular System Learning Outcomes 2.1 Describe circulation as it relates to the ECG. 2.2 Recall the structures of the heart. 2.3 Differentiate between the pulmonary, systemic and coronary circulation. 2.4 Explain the cardiac cycle, and relate the difference between systole and diastole. Learning Outcomes (Contd)<br>2.5a Describe the parts and function of the conduction system. 2.5b Recallthe unique qualities of the heart and their relationship to the cardiac conduction system. 2.5c Explain the conduction system as it relates to the ECG. Learning Outcomes (Contd)<br>2.6a Identify each part of the ECG waveform. 2.6b Describe the heart activity that produces the ECG waveform. 2.1 Circulation and the ECG<br>Transports blood Muscular pump Electrical activity LO 2.1: Describe circulation as it relates to the ECG. ----- Function of heart pump blood to and from all the cells and tissues Blood supplies nutrients &amp; O2 and removes CO2 and waste products Process of transporting blood is known as circulation Circulation dependent upon the heart and its ability to contract or beat The electrical activity of the heart causes the heart to contract Each electrical activity of heart is recorded on the ECG Knowledge of the heart, its functions, and what produces the ECG tracing will provide you with a clear understanding of the tasks you will be performing as an ECG healthcare professional 2.1 Apply Your Knowledge What is the function of the heart? 2.1 Apply Your Knowledge What is the function of the heart?<br>Checkpoint questions What is circulation? The process of transporting blood to and from the body tissues What is recorded on the ECG strip? The electrical activity of the heart ANSWER: To pump blood to and from body tissues 2.2 Anatomy of the Heart Lies in center of chest Under sternum<br>Between the lungs The size of your fist Weighs 10.6 oz or 300 grams LO 2.2: Anatomy of the Heart 2/3 of heart lies left of sternum 2.2 Heart Statistics Average beats per minute = 72<br>Total output = 5 liters per minute LO 2.2: Anatomy of the Heartpowerful muscular pump 140 ml of blood per beat Each day 1800 gallons enough to fill an average size bathtub about 36 times 2.2 Heart Anatomy Pericardium Pericardial space Epicardium Myocardium<br>Endocardium LO 2.2: Anatomy of the Heart -----photo on next slide Pericardium -Sack of tissue surrounding the heart Two layers Parietal layer is the tough outer layer Visceral or epicardium layer is the inner layer and adheres closely to the heart Purpose is to protect the heart from infection and trauma Pericardial space Between parietal and visceral layers of the pericardium Contains approximately 10 to 20 mL of fluid Serves to cushion the heart against trauma Heart consists of three layers: Epicardium outer layer Also known as the pericardium Thin and contains the coronary arteries Myocardium middle, muscular layer, contracts the heart Endocardium inner layer Lines the inner surfaces of the heart chambers and valves Location of the Purkinje fibers is just below this layer Click to Return to Last Screen Viewed<br>2.2 Heart Layers LO 2.2: Anatomy of the Heart Click to Return to Last Screen Viewed 2.2 Heart Chambers Left Atrium Right Atrium Left Ventricle<br>LO 2.2: Anatomy of the Heart Interventricular Septum Varies in thickness Thin in the atria Thick in the Right ventricle Thickest in the left ventricle Thicker = stronger the muscular contraction of that chamber Left ventricle sometimes know as the workhorse of the heart Right Ventricle 2.2 Heart Valves Tricuspid valve Mitral (bicuspid) valve<br>Semilunar valves LO 2.2: Anatomy of the Heart ----- Tricuspid valve located between the right atrium and right ventricle Mitral (bicuspid) valve located between left atrium and left ventricle Mitral and tricuspid valves also known as Atrioventricular (AV) valves prevent backflow of blood from the ventricles to the atria The pulmonary artery and the aorta each have a semilunar valve Half (semi) Lunar (moon) Semilunar valves prevent the backflow of blood into the ventricles Flaps or cusps open to allow the blood to flow then close AV valves open =semilunar valves closed 2.2 Heart Vessels Vena cava Pulmonary artery Pulmonary veins Aorta<br>Coronary arteries LO 2.2: Anatomy of the Heart ----- Vena cava (largest vein in the body) Superior vena cava returns blood from upper body to the heart Inferior vena cava returns blood from lower body to the heart Pulmonary artery Carries deoxygenated blood from the right ventricle to the lungs Pulmonary vein Carries oxygenated blood from the lungs to the left atrium Aorta Carries blood from the left ventricle to the body First branches from aorta are the coronary arteries Coronary arteries Supply blood to the heart muscle 2.2 Heart Valves and Vessels<br>Aorta Tricuspid Valve Vena Cava Bicuspid Valve Aortic Valve Pulmonary Artery Pulmonary Valve Pulmonary Veins LO 2.2: Anatomy of the Heart Click to Return to Last Screen Viewed Using the on-screen pen, draw a line from the label to its location. 2.2 Apply Your Knowledge Which valve of the heart lies between the left atrium and the left ventricle? 2.2 Apply Your Knowledge Which valve of the heart lies between the left atrium and the left ventricle? ANSWER: The mitral or bicuspid valve 2.2 Apply Your Knowledge Name the three layers of the heart. 2.2 Apply Your Knowledge Name the three layers of the heart.<br>Checkpoint Questions LO 2.2 What is the name of the middle layer of the heart (the muscular layer)? Myocardium Which valve is located between the left atrium and left ventricle? Bicuspid or mitral valve ANSWER:The endocardium, myocardium, and epicardium 2.3 Principles of Circulation<br>Pulmonary Systemic Coronary L.O 2.3: Principles of Circulation 2.3 Pulmonary Circulation<br>Enters right atrium Blood passes through thetricuspid valve to the right ventricle Right ventricle pumps to the lungs Blood returns into the left atrium L.O. 2.3: Principles of Circulation ----- Pulmonary Circulation: Deoxygenated blood enters the right atrium from the superior and inferior venae cavae. Blood travels through the tricuspid valve into the right ventricle. The right ventricle pumps the blood through the pulmonary semilunar valve into the pulmonary artery, then into the lungs. In the lungs, the blood is oxygenated. The blood returns to the heart through the pulmonary veins into the left atrium.The left atrium is the last step of pulmonary circulation. 2.3 Systemic Circulation Enters the left atrium and passes through into the left ventricle The left ventricle pumps to the aorta From the aorta, blood circulates throughout the body Deoxygenated blood returns to the heart L.O 2.3:Principles of Circulation ----- Oxygenated blood enters the left atrium and travels through the mitral valve into the left ventricle. The left ventricle pumps the blood through the aortic semilunar valve into the aorta. After traveling through the body,the deoxygenated blood returns to the heart through the superior and inferior venae cavae. 2.3 Coronary Circulation A<br>L.O. 2.3:Principles of Circulation 2.3 Coronary Circulation B<br>L.O. 2.3:Principles of Circulation 2.3 Coronary Circulation Oxygenated blood travels from left ventricle to the coronary arteries Coronary arteries supply entire heart Deoxygenated blood returns to the right atrium L.O. 2.3:Principles of Circulation ----- Oxygenated blood from the left ventricle travels through the aorta to the coronary arteries. Two main coronary arteries-left main and right main. These arteries branch to supply oxygenated blood to the entire heart. The left main artery has more branches because the left side of the heart is more muscular and requires more blood supply. The deoxygenated blood travels through the coronary veins and is collected in the coronary sinus, which empties the blood directly into the right atrium. The Heart as a Pump Each ventricle pumps 70 mL of blood during contraction this volume of blood that is ejected with each contraction is referred to as stroke volume This amount varies depending on gender, level of fitness, disease state, or genetics The volume of blood pumped each minute is referred to as cardiac output Average cardiac output is approx. 5 liters/min. Volume of blood decreases = heart rate decreases Contractile force decreases = cardiac output decreases Decreased output causes pallor, confusion, low blood pressure, nausea, and dizziness. Cardiac output is estimated by multiplying heart rate by stroke volume HR x SV = CO 2.3 Apply Your Knowledge Great!<br>Which vessels transport blood from the lungs to the left atrium? Great! 2.3 Apply Your Knowledge Great!<br>Which vessels transport blood from the lungs to the left atrium? ANSWER: The pulmonary veins Checkpoint questions(2.3): What are the first vessels to branch off the aorta known as? Coronary arteries Describe the three types of circulation. The pathways for pumping blood to and from the lungs are known as pulmonary circulation. The pathways for pumping blood throughout the body and back to the heart are known as systemic circulation. The circulation of blood to and from the heart muscle is known as coronary circulation. What is cardiac output? The volume pumped each minute is referred to as cardiac output. Great! 2.4 The Cardiac Cycle L.O 2.4: The Cardiac Cycle<br>Each beat has two phases contraction and relaxation which together makeup the cardiac cycle Relaxation = diastole expanding and refilling Contraction = systole squeezing blood out 2.4 The Cardiac Cycle (Contd)<br>L.O 2.4:The Cardiac Cycle 2.4 Diastole Relaxation Phase<br>Blood returns to the heart via the superior and inferior vena cava Blood flows from the right atrium into the right ventricle Blood from the pulmonary veins flows from the left atrium into the left ventricle L.O. 2.4:The Cardiac Cycle ----- Blood from the upper body returns via the superior vena cava. Blood from the lower body returns via the inferior vena cava. The right atrium fills with blood, pushes open the tricuspid valve, and into the right ventricle. Blood returns from the lungs via the pulmonary veins to the left atrium, then forces the mitral valve to open to allow blood flow to the left ventricle. 2.4 Systole Contraction Phase<br>Contraction creates pressure, opening the pulmonary and aortic valves Blood from the right ventricle flows to the lungs Blood from the left ventricle flows through the aorta to the body L.O. 2.4:The Cardiac Cycle ----- Blood is pushed into the lungs to exchange oxygen and carbon dioxide by the right ventricle. Blood from the left ventricle is pushed through the aorta to be distributed through the body to provide oxygen for tissues and to remove carbon dioxide. Listening with a stethoscope you will hear two sounds: lubb and dupp which are made by the opening and closing of the valves caused by the contraction of the heart Lubb sound made during the systolic phase by the contraction of the ventricles and the closing of the mitral and tricuspid valves Dupp sound is made during the diastolic phase. It is shorter and occurs during the beginning of ventricular relaxation. 2.4 Apply Your Knowledge The relaxation phase of the cardiac cycle is known as: 2.4 Apply Your Knowledge The relaxation phase of the cardiac cycle is known as: ANSWER: Diastole Checkpoint Questions (LO2.4) What is the cardiac cycle? The contraction and relaxation of the heart together make up the cardiac cycle. How are diastole and systole the same? They are both parts of the cardiac cycle. 2.5 Unique Qualities of the Heart<br>Automaticity Conductivity Contractivity Excitability L.O. 2.5 a., b., c.:Conduction System of the Heart Pumping cycle is controlled by electrical impulses the impulses stimulate contraction of the heart muscle and absence of impulses allows the heart muscle to relax Impulses are initiated by specialized pacemaker cells in the heart. Impulses are transferred through the heart by the conduction system The working cells respond by shortening, causing cardiac contraction and blood to flow ----- Automaticity hearts ability to initiate an electrical impulse Conductivity ability of myocardial cells to receive and conduct (transmit) electrical impulses Contractility ability of the heart muscle to shorten in response to an electrical impulse Excitability ability of the heart to respond to an impulse or stimulus Without these qualities the heart would not beat and would not be rhythmical 2.5 Regulation of the Heart<br>Autonomic Nervous System Speeds up or slows down the heart rate Sympathetic branch can increase the heart rate Parasympathetic branch can decrease the heart rate L.O. 2.5 a., b., c.:Conduction System of the Heart ----- In addition to automaticity, the heartbeat is controlled by the ANS, which is involuntary Sympathetic branch can increase the heart rate in response to norepinephrine. Happens when you are under stress or frightened Normal rate of heart is 60 to 100 beats a minute When sympathetic branch of ANS stimulated the heartbeat speeds up Parasympathetic branch can decrease the heart rate via the vagus nerve. Acts like the brake of the heart Other factors can also affect the heart Exercise, stress, or fever can increase the rate The cardiac control center, in the brain, sends impulses to decrease the heart rate when the BP rises Levels of potassium and calcium Low potassium ions in the blood, heart rate decreases High potassium ionscauses abnormal heart rate or rhythm Low calcium depresses heart actions High calcium causes contractions that are longer then normal heart contractions 2.5 Pathways for Conduction<br>SA node AV node Bundle of His Bundle branches Purkinje fibers L.O. 2.5 a., b., c.:Conduction System of the Heart 2.5 Sinoatrial (SA) Node Located in upper right portion of right atrium Initiates the heartbeat Pacemaker of the heart ( beats per minute) Normal conduction begins in SA node L.O. 2.5 a., b., c.:Conduction System of the Heart SA &amp; AV nodes are small, round structures that consist of many specialized cardiac cells. Automaticity of the fibers in the SA node produces the contraction of the right and left atria 2.5 Atrioventricular (AV) Node<br>Located on the floor of the right atrium Causes delay in the electrical impulse, allowing for blood to travel to ventricles Can act as pacemaker if SA node is not working (40-60 bpm) L.O. 2.5 a., b., c.:Conduction System of the Heart 2.5 Bundle of His (AV bundle)<br>Located next to the AV node Transfers electrical impulses from the atria to the ventricles via bundle branches L.O. 2.5 a., b., c.:Conduction System of the Heart ----- The bundle branches are located along the left and right side of the interventricular septum. 2.5 Bundle Branches Split the electrical impulse down the right and left side From interventricular septum, the impulse activates myocardial tissue, causing contraction Contractions occur in left-to-right pattern L.O. 2.5 a., b., c.:Conduction System of the Heart 2.5 Purkinje Fibers Electrical pathwa...</p>

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