Assessing the cardiovascularSystemDr/Magda Bayoumi
Layers of the Heart Endocardium: Inner layer of heart; a smooth, thin layer of endothelium and connective tissue. smooth inner lining of the heart. Myocardium: Middle and thickest layer of heart; heart muscle. Responsible for cardiac contraction. Epicardium: The layer of serous pericardium on heart’s surface. Contains main coronary blood vessels.
Pericardium: Sac that surrounds the heart and roots of the great vessels. Composed of two layers: fibrous pericardium (outer layer of fibrous connective tissue) and serous pericardium. Serous pericardium also has two layers: outer or parietal layer That lines the fibrous layer and visceral or inner layer that lines the heart and is also called the Epicardium. Serous pericardium contains pericardial fluid (10–20 mL of serous fluid). Pericardial fluid moistens the pericardial sac between the two layers and prevents friction during systole and diastole.
The Circulatory System The circulatory system has two main networks, the pulmonary circulation and the systemic circulation. coronary circulation is part of the systemic circulation and supplies the heart itself. The pulmonary circulation involves blood vessels that circulate blood through the pulmonary arteries, the lungs, and the pulmonary veins.
Unoxygenated blood enters the pulmonary circulation from the right and left pulmonary arteries. The unoxygenated blood then flows through the pulmonary arterioles to the lung capillaries, where the exchange of carbon dioxide and oxygen occurs. The oxygenated blood then enters the pulmonary venules that lead to the pulmonary veins. Oxygenated blood is then carried back to the left atrium through the right and left pulmonary veins.
Systemic Circulation The systemic circulation is responsible for supplying oxygen to every cell in the body through the arterial system and then returning unoxygenated blood to the heart through the venous system. Oxygenated blood flows into the left atrium from the pulmonary circulation. The left atrium then pumps the oxygenated blood into the left ventricle, which in turn expels the oxygenated
Coronary Circulation The coronary circulation consists of the right and left coronary arteries and the coronary sinus and cardiac veins. The coronary arteries are the first branches off the aorta. The cardiac veins drain into the coronary sinus, which in turn drains directly into the right atrium.
blood through the aorta into the arterial systemic circulation. From the aorta, blood then flows through smaller arterioles to the systemic capillaries. The systemic capillaries link the arterial and venous systems. At this point, exchange of oxygen, nutrients, and wastes occurs. From the capillaries, unoxygenated blood then flows through the venules, into the larger veins, and then to the superior and inferior vena cavae. Unoxygenated blood then enters the right atrium and is pumped to the right ventricle into the pulmonary circulation to continue the cycle.
Mechanisms of Heart Sounds Heart sounds are the result of events within the heart. The movement and pressure of the blood (hemodynamics), the activity of the electrical conduction system, and the movement of the valves affect the sounds that you hear
The Cardiac Cycle The cardiac cycle comprises systolic and diastolic phases. The systolic phase is the contraction or emptying phase, and the diastolic phase is the resting or filling phase. The atria and ventricles alternate through the systolic and Diastolic phases; while the atria are contracting, the ventricles are relaxing, and vice versa.
Ventricular Diastole Ventricular diastole marks the beginning of the filling phase. Very shortly after the onset of ventricular diastole, the pressure in the ventricles is less than that of the atria, and the mitral and tricuspid valves open to allow filling of the ventricles (the rapid-filling phase of diastole).
Ventricular Systole With ventricular contraction, the pressure in the ventricles will exceed that in the atria. This results in closure of the mitral and tricuspid valves and marks the beginning of ventricular systole. While the ventricles are contracting and blood is being propelled from them, the atria are relaxed (atrial diastole) and are filling.
The amount of blood ejected from the heartwith each contraction is referred to as the stroke volume. The cardiac output is the amount of blood ejected per minute. Cardiac output equals stroke volume multiplied by heart rate.
The Stroke Volume Preload refers to the volume of blood in the ventricles at t he end of diastole. An increase in venous return to the heart will, in turn, increase preload. Factors that affect venous return include: Venous blood reservoirs Skeletal muscle pump: Venous tone: Respiratory pump:
After load is simply the work that theheart has to do to push blood into theaorta and around the body.
Afterload reflects the end-systolic volume. It is affected by the amount of resistance the ventricles have to contract against. An increase in after-load results in a decrease in stroke volume. After-load may be affected by: ■ Arterial elasticity. ■ Peripheral vascular resistance. ■ Aortic valve resistance. ■ Viscosity and volume of blood. ■ Contractility,which reflects the force of contraction. ■ Positive inotropes,which increase the force of contraction. ■ Negative inotropes, which decrease the force of contraction.
The Heart’s Electrical Conduction System The specialized cells of the conduction system have automaticity,excitability, conductivity and refractoriness. Automaticity is the cell’s ability to initiate an impulse. Excitability is the cell’s ability to respond to an impulse and create an action potential. Conductivity is the cell’s ability to transmit an impulse. Refractoriness is the cell’s ability to respond to the transmitted impulse.
The sinoatrial (SA) node is the normal pacemaker of the heart located in the right atrium near the superior vena cava entrance point. The SA node paces the normal adult heart at 60 to 100 BPM. The activation of the SA node passes through the atria and results in atrial
electrical activity is then conducted to the atrioventricular (AV) node.This node is located at the base of the right atrium between the atria and the ventricles. It has the ability to pace the heart at a rate of 40 to 60 BPM. The electrical impulse is then transmitted. from the AV node to the bundle of His, which divides into two branches, the right and the left, which traverse the interventricular septum. Finally, the impulse is transmitted to small branches that eventuate into the Purkinje fibers, which stimulate the ventricles to contract. The pacer ability of the bundle of His is 20 to 40 BPM.
The Valves S1, the first heart sound, results from the closure of the mitral (M1) and tricuspid (T1) valves. M1 and T1 normally close within approximately 0.02 second or less. These valve sounds are often heard as a single sound. S1 is best heard at the apex or left lateral sternal border (LLSB) with the diaphragm of the stethoscope.
The Second Heart Sound (S2) When the systolic pressure in the ventricles decreases below that of the aorta and the pulmonary artery (toward the end of systole), the aortic (A2) and pulmonic (P2) valves close, producing the second heart sound. Clinically, this sound marks the end of systole and the beginning of diastole. A2 and P2 normally close about 0.02 second from each other; consequently, they may occasionally be heard as a single sound.
Extra Heart Sounds Additional sounds that may be heard during auscultation , include early ejection click, mid systolic ejection click, opening snap, S3, and S4.These sounds do not always indicate pathology.
Interaction With Other Body Systems ENDOCRINE Distributes hormones throughout body via circulatory system. Cardiac muscle cells secrete atrial natriuretic peptide (ANP), which helps maintain fluid and electrolyte balance and lowers volume and blood pressure. Erythropoietin regulates RBC production. Epinephrine and norepinephrine increase heart rate and force of contraction. URINARY Helps regulate volume within vascular system. Renin/angiotensin system affects B/P. Erythropoietin affects RBC production.
LYMPHATIC Delivers WBCs and antibodies to fight pathogens. And heart from pathogens Protects vascular system.REPRODUCTIVE Distributes reproductive hormones. Delivers nutrients to reproductive organs. Vascular system needed for changes that occur during sexual arousal. Premenopausal women have lower incidence of heart disease.
RESPIRATORY RBCs exchange oxygen and carbon dioxide in lungs and transport it to peripheral system. Provides oxygen to and removes wastes from cardiovascular system. Lungs convert angiotensin I to II, which helps maintain blood pressure.
INTEGUMENTARY Responds to skin injury or infection by delivering clotting factors and immune system response to affected area. Stimulation of mast cells in response to injury or infection. Produces local changes in blood pressure and release of ADH, which helps blood flow and capillary permeability.
SKELETAL Delivers calcium and minerals to bones for bone growth. Delivers parathormone and calcitonin. Provides calcium for normal heart muscle contraction. Produces blood cells in bone marrow. Skeletal framework protects heart.MUSCULAR Delivers nutrients to muscles and throughout circulatory system. Removes carbon dioxide, lactic acid and heat produced by muscle activity. Muscles provide protection for neck vessels. Heart is muscle responsible for pumping blood. Muscle contraction of legs helps with venous return.
NEUROLOGICAL Endothelial cells of brain capillaries form a semi-permeable membrane that maintains blood-brain barrier. Controls peripheral circulation and heart rate and increases blood volume and pressure.DIGESTIVE Delivers nutrients and hormones from site of absorption and transports nutrients and toxins to liver. Supplies cardiovascular system with nutrients and absorbs water and ions that help maintain blood volume.
Korotkoff’s Sounds: When you take your patient’s BP, you may hear five distinct phases called Korotkoff’s sounds.These phases occur because the BP cuff partially obstructs blood flow and disturbs the laminar flow pattern, causing turbulence. Korotkoff phases include the following:■ Phase I: A faint, clear, rhythmic tapping noise that gradually increases in intensity. Intraluminal pressure and cuff pressure are equal.■ Phase II: A swishing sound that is heard as the vessel distends with blood.■ Phase III: Sounds become more intense. Vessel is open in systole but not in diastole.■ Phase IV: Sounds begin to muffle, and pressure is closest to diastolic arterial pressure.■ Phase V: Sounds disappear because vessel remains open.
Central Artery and Jugular Veins The sternocleidomastoid and trapezius muscles are helpful in locating these vessels. The carotid artery and the internal jugular run parallel to each other along the sternocleidomastoid muscle toward the sternal notch. The external jugular crosses the internal jugular and lies posterior to the sternocleidomastoid muscle.
Is It a Jugular Wave or a Carotid Arterial Wave?■ Carotid pulsation is normally palpable; jugular pulsation is not. Because jugular pulsation is a low-pressure wave, applying pressure can easily obliterate it.■ Carotid pulsation is not affected by position; jugular venous pulsation is.■ Carotid pulsation is unaffected by respirations; jugular venous pulsation is.■ Carotid pulsation has one positive wave; jugular venous pulsation has three positive waves
These graphics represent the normal cardiac pulsations and heart sounds. The jugular venouspulsation normally has 3 positive waves—the a, c, and v waves and 2 negative troughs—x and ytroughs. The "a" wave is approximately synchronous with the first heart sound and just precedesthe carotid upstroke. The "v" wave coincides approximately with the second heart sound. Thenormal carotid artery pulsation has a single positive wave during systole, followed by thedicrotic notch (about the time of the second heart sound). The apex impulse represents the normalbrief, palpable systolic impulse occurring at the time of the first heart sound. In young normalindividuals there may be a palpable early diastolic filling wave representing the rapid fillingphase of ventricular diastole and corresponding to the normal third heart sound. Auscultation atthe aortic area reveals a normal first heart sound (S1) and second heart sound (S2). S2 is normallylouder than S1 in this area. At the pulmonary area there is normal inspiratory (physiologic)splitting of the second sound due to asynchronous aortic and pulmonic closure. The aorticcomponent of the second heart sound (A2) normally precedes the pulmonic component (P2). Atthe tricuspid area there is normal splitting of the first heart sound due to asynchronous mitral andtricuspid closure. The mitral component of the first sound (M1) normally precedes the tricuspidcomponent (T1). At this area, physiologic splitting of the second sound may also be appreciated.At the mitral area, the first and second heart sounds are normal. The first sound is normallylouder than the second heart sound and only the aortic component of the second heart sound isnormally appreciated. Occasionally a third heart sound is normal, reflecting deceleration of bloodinto the left ventricle during the rapid filling phase of early diastole. Children and young adultsoften have normal or physiologic third heart sounds.