Cardiovascular System PDF

Cardiovascular System Kristine A. Velasco, RN, UAE-RN, US-RN,  Anatomy of the Heart -is a hollow, muscular organ located at the center of the thorax. -it occupies the space between the lungs (mediastinum) and rests on the diaphragm. -weighs approximately 300gra...

Cardiovascular System Kristine A. Velasco, RN, UAE-RN, US-RN,  Anatomy of the Heart -is a hollow, muscular organ located at the center of the thorax. -it occupies the space between the lungs (mediastinum) and rests on the diaphragm. -weighs approximately 300grams (10.6 oz.) -the weight and the size of the heart are influenced by age, gender, body weight, extent of physical exercise and conditioning and heart disease. -supplies oxygen and other nutrients to the tissues by pumping blood. Loading…  3 layers 1. Inner layer (endocardium) 2. Middle layer (myocardium) 3. Exterior Layer (epicardium) Loading…  Diastole - All four chambers relax simultaneously, which allows the ventricles to fill in preparation for contraction. - Commonly referred to as “period of ventricular filling” Systole Loading… -contraction of the atria and ventricles. - Atrial systole occurs first, just at the end of diastole followed by ventricular systole. Pulmonary Artery -the only artery that carries deoxygenated blood. Superior Vena Cava - (Head, neck, and upper extremities) Inferior Vena Cava -(Trunk and lower extremities) Aorta -distributes oxygenated blood throughout the system  Apical Pulse - Point of maximal pulse - Located at the intersection of the midclavicular line of the left chest wall and the fifth intercostal space  Heart Valves - The 4 valves in the heart permit blood to flow in only one direction. - The valves are composed of thin leaflets of fibrous tissue, open and close in response to the movement of blood and pressure changes within the chambers. 2 types of valves 1. Atrioventricular Valve 2. Semilunar Valve  Atrioventricular Valves 1. Tricuspid Valve -composed of three cusps or leaflets, separated the right atrium from the right ventricle. 2. Mitral Valve (Bicuspid) - Lies between the left atrium and the left ventricle. *during diastole, tricuspid and mitral valves are open allowing the blood in the atria to flow freely into the relaxed Ventricles. As the ventricles contracts and blood flows upward into the cusps of the tricuspid and mitral valves Causing them to close. Semilunar Valves 2. Pulmonic Valve - Valve between the right ventricle and the pulmonary artery 2. Aortic valve - Valve between the left ventricle and the aorta *semilunar valves are forced open during ventricular systole as blood is ejected from the right and left ventricles into The pulmonary artery and aorta respectively. Coronary Arteries -the left and right coronary arteries and their branches supply arterial blood flow to the heart. -normal heart rate of 60 to 80 bpm, there is an ample time during diastole for myocardial perfusion. -as heart rate increases, diastolic time is shortened, which may not allow adequate time for myocardial perfusion  -patients are at risk for myocardial ischemia during tachycardia especially with patients with CAD. -the left coronary artery has 3 branches: 1. Left main coronary artery –artery from the point of origin to the first major branch 2. Left anterior descending artery –courses down the anterior wall of the heart 3. Circumflex artery – circles around to the lateral left wall of the heart. - The right side of the heart is supplied by the Right Coronary Artery - The posterior wall of the heart supplied by the Posterior Descending Artery Myocardium -is the middle, muscular layer of the atrial and ventricular walls. - composed of specialized cells called Myocytes – this fibers encircles the heart in a figure of eight from base (top) to the apex (bottom) Function of the Heart Cardiac Conduction System -generates and transmits electrical impulse that stimulate contraction of the myocardium. -stimulates atria first before ventricles. 2 types of SPECIALIZED ELECTRICAL CELLS Nodal Cells Purkinje Cells 3 Physiologic Characteristics Automaticity – ability to initiate an electrical impulse Excitability – ability to respond to an electrical impulse Conductivity – ability to transmit an electrical impulse from one cell to another. Sinoatrial Node (SA Node) –primary pacemaker of the heart Atrioventricular Node (AV Node) -the secondary pacemaker of the heart *both are composed of Nodal Cells SA Node – in a normal adult heart has an inherent firing rate at 60 to 100 impulses per minute; AV Node – inherent firing rate 40 to 60 per minute However the rate changes according to metabolic demand of the body. Initially, the impulse is conducted through a bundle of specialized conducting tissue, referred to as bundle of His. Impulses travel through the bundle branches to reach terminal point in the conduction system Purkinje Fibers. -this fibers are composed of Purkinje cells that rapidly conducts impulses throughout the thick walls of the ventricles Cardiac Output - refers to the total amount of blood ejected by one of the ventricles in liters per minute. -the cardiac output in a resting adult is 4 to 6 l/min Stroke Volume - is the amount ejected from one ventricles per heartbeat. - average resting stroke volume is about 60 to 130 mL Preload - refers to the degree of stretch of the ventricular cardiac muscle fibers at the end of diastole. Afterload - resistance to ejection of blood from the ventricle. Contractility Loading… - refers to the force generated by the contracting myocardium Gerontologic Considerations -Changes in cardiac structure and function occur with age. -size of the heart increases due to hypertrophy (thickening of heart walls) which reduces the volume of blood The chambers can hold. -the valves due to stiffening, no longer close properly. -results backflow of blood creates heart murmurs, a common finding in older adults.  Gender Considerations - heart of woman tends to be smaller than that of a man. -arteries are narrower in diameter in woman -women develop CAD 10 years later than men as women have the benefit of the cardioprotective effects of a female Hormone estrogen. 3 major effects of estrogen 1. An increase in HDL high density lipoprotein that transports cholesterol out of the arteries. 2. A reduction in low-density lipoprotein that deposits cholesterol in the artery. 3. Dilatation of the blood vessels, which enhance blood flow to the heart. Assessment of the Cardiovascular System Cardiovascular Structure Structural Changes Atria Increase size of left atrium Thickening of Endocardium Left Ventricle Endocardial Fibrosis Myocardial thickening(hypertrophy) Infiltration of fat into myocardium Valves Thickening and rigidity of AV valves Calcification of aortic valve Conduction System Connective tissue collects in SA node, AV node and bundle branches – decrease # SA node cells, decrease #of AV, bundle of His and right and left bundle branch cells Sympathetic Decrease response to beta-adrenergic Nervous System stimulation (regulation of heart function under conditions) Aorta and arteries Stiffening of vasculature Decrease elasticity and widening of aorta Elongation of aorta, displacing the brachiocephalic artery upward Baroreceptor Decrease sensitivity of baroreceptors in the Response carotid artery and aorta to transient episodes of HTN and hypotension Functional Changes History and Physical Findings Increase atrial irritability Irregular heart rhythm from atrial dysrhythmias Left ventricle stiff and less compliant; Fatigue; low exercise tolerance; s&sx of progressive decline in the CO; HF or ventricular dysrhythmias. increase risk for ventricular PMI palpated lateral to the MCL dysrhythmias; prolonged systole Decrease intensity S1, S2; split s2 S4 may be present Abn. Blood flow across valves during Murmurs may be present cardiac cycle Thrill may be palpated if significant murmur is present Slower SA node rate of impulse discharge; Bradycardia; Heart Block; ECG Changes slowed conduction across AV node and consistent with slowed conduction (Increase Ventricular Conduction system PR interval, widened QRS complex) Low adaptive repose to exercise; contractility Fatigue and HR slower to respond to exercise Diminished exercise tolerance demands; HR takes more time to return to Decrease ability to respond to stress baseline Left ventricular hypertrophy Progressive increase in systolic BP; slight increase in Diastolic BP; widening pulse pressure, pulsation visible above right clavicle Baroreceptor unable to regulate HR and Postural BP changes and reports of feeling dizzy, vascular tone, causing slow response to fainting when moving from lying to sitting and postural changes in body position standing position Health History - patient’s ability to recognize cardiac symptoms and to know what to do when they occur is essential for effective self-care management. Major Barriers -lack of knowledge -attributing symptoms to benign source -denying symptom significance -feeling embarrassed about having symptoms Nurses should include family members or caregivers in assessing and taking history of the patient. Assessment Findings Associated Causes and Conditions Clubbing of the fingers and toes (thickening of Chronic hemoglobin desaturation most often to Congenital HD, skin under the fingers or toes) advanced pulmonary diseases. Cool/cold skin and diaphoresis Low cardiac output (e.g. Cardiogenic Shock, Acute MI) causing Sympathetic Nervous system stimulation with resultant vasoconstriction Cold, pain, pallor of the fingertips or toes Intermittent arteriolar vasoconstriction (Raynaud disease), skin may change in color from white, blue, and red accompanied by numbness, tingling and burning pain. Cyanosis, central (a bluish tinged in the tongue Serious cardiac disorders (pulmonary edema, cardiogenic shock, and buccal mucosa) congenital heart disease) result in venous blood passing through the pulmonary circulation without being oxygenated Cyanosis, peripheral (a bluish tinge, most often of Peripheral vasoconstriction, allowing more time for the hemoglobin the nails and skin of the nose, lips, earlobes, and molecules to become desaturated. It can be caused by exposure to cold extremities) environment, anxiety, or & cardiac output Ecchymosis or bruising (a purplish-blue color Blood leaking outside of the blood vessels fading to green, yellow, or brown) Excessive bruising is a risk for patients on anticoagulants or platelet- inhibiting medications Edema, lower extremities (collection of fluid in the Heart failure and vascular problems (PAD, chronic venous insufficiency, interstitial spaces of the tissues) deep vein thrombosis, thrombophlebitis) Hematoma (localized collection of clotted blood in the Bleeding after catheter removal/tissue injury in patients on tissue) anticoagulant/antichrombotic agents Pallor (4 skin color in fingernails, lips, oral mucosa, Anemia or arterial perfusion. Suspect PAD if feet develop pallor after and lower extremities) elevating legs 60° from a supine position Rubor (a reddish-blue discoloration of the legs, seen Filling of dilated capillaries with deoxygenated blood, indicative of PAD within 20 s to 2 min after placing in a dependent position) Ulcers, feet and ankles: Superficial, irregular ulcers at Rupture of small skin capillaries from chronic venous insufficiency medial malleolus. Red to yellow granulation tissue Ulcers, feet and ankles: Painful, deep, round ulcers on Prolonged ischemia to tissues due to PAD. Can lead to gangrene feet or from exposure to pressure. Pale to black wound base Thinning of skin around a pacemaker or an Erosion of the device through the skin implantable cardioverter defibrillator Xanthelasma (yellowish, raised plaques observed Elevated cholesterol levels (hypercholesterolemia) along nasal portion of eyelids) PAD, peripheral arterial disease. Blood Pressure -It is affected by factors such as cardiac output; distention of the arteries; and the volume, velocity, and viscosity of the blood. -Pulse pressure, which normally is 30 to 40 mm Hg, indicates how well the patient maintains cardiac output. -increases in conditions that elevate the stroke volume (anxiety, exercise, bradycardia), -reduce systemic vascular resistance (fever), or reduce distensibility of the arteries (atherosclerosis, aging, HTN). -decreased pulse pressure reflects reduced stroke volume and ejection velocity (shock, HF, hypovolemia, mitral regurgitation) or obstruction to blood flow during systole (mitral or aortic stenosis. -pulse pressure of less than 30 mm Hg signifies a serious reduction in cardiac output and requires further cardiovascular assessment Postural (Orthostatic) Blood Pressure Changes There is a gravitational redistribution of approximately 300 to 800 mL of blood into the lower extremities and the gastrointestinal system immediately upon standing. These changes reduce venous return to the heart, compromising preload that ultimately reduces stroke volume and cardiac output. Assessing Patients for Postural Hypotension Position the patient supine for 10 minutes before taking the initial blood pressure (BP) and heart rate measurements. Reposition the patient to a sitting position with legs in the dependent position, wait 2 minutes, then reassess both BP and heart rate measurements. If the patient is symptom free or has no significant decreases in systolic or diastolic BP, assist the patient into a standing position, obtain measurements immediately, and recheck in 2 minutes; continue measurements every 2 min for a total of 10 minutes to rule out postural hypotension. Return the patient to a supine position if postural hypotension is detected or if the patient becomes symptomatic. Document heart rate and BP measured in each position (e.g., supine, sitting, and standing) and any signs or symptoms that accompany the postural changes. Normal Heart Sounds Normal heart sounds, referred to as S1 and S2, - are produced by closure of the AV valves and the semilunar valves, respectively. -When the heart rate is within the normal range, systole is much shorter than the period between S2 and S1 (diastole). - However, as the heart rate increases, diastole shortens. S1-First Heart Sound -Tricuspid and mitral valve closure creates the first heart sound (S.). The word "lub" is used to replicate its sound. S, is usually heard the loudest at the apical area. S, is easily identifiable and serves as the point of reference for the remainder of the cardiac cycle. S2-Second Heart Sound -Closure of the pulmonic and aortic valves produces the second heart sound (S2), commonly referred to as the "dub". sound. The aortic component of S, is heard the loudest over the aortic and pulmonic areas. However, the pulmonic component of S, is a softer sound and is heard best over the pulmonic area. S3-Third Heart Sound -An S, ("DUB") is heard early in diastole during the period of rapid ventricular filling as blood flows from the atrium into a noncompliant ventricle. - It is heard immediately after S,. "Lub-dub-DUB" is used to imitate the abnormal sound of a beating heart when an S is present. It represents a normal finding in children and adults up to 35 or 40 years of age. - In older adults, an S, is a significant finding, suggesting HF. It is best heard with the bell of the stethoscope. If the right ventricle is involved, a right-sided S, is heard over the tricuspid area with the patient in a supine position. A left-sided S, is best heard over the apical area with the patient in the left lateral position. S4-Fourth Heart Sound S4 ("LUB") -S4 heard just before S1 is generated during atrial contraction as blood forcefully enters a noncompliant ventricle. -This resistance to blood flow is due to ventricular hypertrophy caused by hypertension, CAD, cardiomyopathies, aortic stenosis, and numerous other conditions. "LUB lub-dub" is the mnemonic used to imitate this gallop sound. -S4, produced in the left ven-tricle, is auscultated using the bell of the stethoscope over the apical area with the patient in the left lateral position. -A right-sided S4, although less common, is heard best over the tricuspid area with the patient in supine position. -There are times when both S, and S, are present, creating a quadruple rhythm, which sounds like "LUB lub-dub DUB." -During tachycardia, all four sounds combine into a loud sound, referred to as a summation gallop. Murmurs -Murmurs are created by turbulent flow of blood in the heart. -The causes of the turbulence may be a critically narrowed valve, a malfunctioning valve that allows regurgitant blood flow, a congenital defect of the ventricular wall, a defect between the aorta and the pulmonary artery, or an increased flow of blood through a normal structure (e.g., with fever, pregnancy, and hyperthyroidism). -Murmurs are characterized and consequently described by several characteristics, including their timing in the cardiac cycle, location on the chest wall, intensity, pitch, quality, and pattern of radiation. Friction Rub -A harsh, grating sound that can be heard in both systole and diastole is called a friction rub. -It is caused by abrasion of the inflamed pericardial surfaces from pericarditis. -Because a friction rub may be confused with a murmur, care should be taken to identify the sound and to distinguish it from murmurs that may be heard in both systole and diastole. -A pericardial friction rub can be heard best using the diaphragm of the stethoscope, with the patient sitting up and leaning forward.