Clinical Physiology 3_ The Heart (Printed) PDF

Clinical Physiology III Fundamental Physiologic Basis of the Vital Signs BMS 100 Week 3 The Cardiac Exam • Heart Anatomy • Surface Anatomy • Chambers • Valves And Great Vessels • Basic Cardiac Physiology • The Cardiac Cycle • Valvular Movements • The Cardiac Physical Exam • Surface Anatomy And Au...

Clinical Physiology III Fundamental Physiologic Basis of the Vital Signs BMS 100 Week 3 The Cardiac Exam • Heart Anatomy • Surface Anatomy • Chambers • Valves And Great Vessels • Basic Cardiac Physiology • The Cardiac Cycle • Valvular Movements • The Cardiac Physical Exam • Surface Anatomy And Auscultation • Phases Of The Cardiac Cycle And Heart Sounds • Murmurs and Valvular Abnormalities • Locations Of The Major Pulses The Heart Chambers – Anatomy Note the location of: • The chambers: ▪ The left and right atrium ▪ The left and right ventricle ▪ The interventricular septum 🡪 the thick muscular wall that separates the left and right ventricle • The great vessels: ▪ The pulmonary trunk + left & right pulmonary arteries ▪ The aorta ▪ The superior and inferior vena cavae ▪ The pulmonary veins Basic Heart Anatomy Anatomy & Physiology, 2e. p. 755, fig 19.4 https://openstax.org/books/anatomy-and-physiology-2e The Heart - Valves There are two major types of valves that ensure one-way flow through the heart Atrioventricular valves • Between the atria and the ventricles – prevent backflow ▪ So when the left ventricle contracts, blood moves into the aorta, not the left atrium ▪ So when the right ventricle contracts, blood moves into the left atrium, not the right atrium Semilunar (“half-moon”) valves • Between the ventricles and the great arteries ▪ So when the ventricle relaxes during diastole, blood isn’t “sucked back” into that ventricle ▪ Why does that arterial blood still move forwards? The Heart - Valves Atrioventricular valves • Larger, and more “floppy” in nature • Anchored by the chordae tendineae ▪ Keeps them from “flopping back” (prolapse) into the atria during ventricular contraction Semilunar (“half-moon”) valves • Smaller and “tighter” ▪ Therefore do not require chordae tendineae to anchor them Basic Heart Anatomy Anatomy & Physiology, 2e. p. 755, fig 19.4 https://openstax.org/books/anatomy-and-physiology-2e Heart Anatomy • Papillary muscles • Chordae tendineae • The general shape of the semilunar and atrioventricular (AV) valves • What structures would be located anteriorly, and which would be located posteriorly? Anatomy & Physiology, 2e. p. 761, fig 19.9 https://openstax.org/books/anatomy-and-physiology-2e Anterior View Of The Heart Anatomy & Physiology, 2e. p. 758, fig 19.6 https://openstax.org/books/anatomy-and-physiology-2e Posterior View Of The Heart Anatomy & Physiology, 2e. p. 758, fig 19.6 https://openstax.org/books/anatomy-and-physiology-2e Anterior vs. Posterior Surfaces • The anterior surface of the heart is easier to auscultate and palpate than the posterior surface Anterior surface – major structures • Part of the right atrium (auricle) • Right ventricle • The “tip” of the left ventricle - apex ▪ It’s the easiest place to palpate the cardiac impulse in most people ▪ Point of Maximal Impulse (PMI) • The superior – lateral side of the left ventricle • Both semilunar valves are somewhat anterior to the AV valves Valves – the superior aspect Anatomy & Physiology, 2e. p. 765, fig 19.13 and p. 784, fig. 19.27 https://openstax.org/books/anatomy-and-physiology-2e Valves – the superior aspect Anatomy & Physiology, 2e. p. 764, fig 19.12 and p. 784, fig. 19.27 https://openstax.org/books/anatomy-and-physiology-2e The Heart – Surface Anatomy Surface Anatomy: Using superficial (usually palpable) anatomical landmarks during the physical exam to localize structures that lie deeper in the body • Used for a variety of physical exam maneuvers ▪ Correlating a sound with a deep anatomical structure ▪ Correlating a palpation finding (mass, pain) with a likely deep anatomical structure Bones Of The Thoracic Cage Palpation tips for the thoracic cage: • Find the “bump” between the manubrium and body of the sternum • Angle of Louis • Right below this is the 2nd intercostal space • This makes landmarking and rib-counting much easier Anatomy & Physiology, 2e. p. 259, fig. 7.32 https://openstax.org/books/anatomy-and-physiology-2e The Heart – Surface Anatomy Anatomy & Physiology, 2e. p. 753, fig 19.2 and p. 259, fig. 7.32 https://openstax.org/books/anatomy-and-physiology-2e The Heart – Surface Anatomy Key locations for auscultation and palpation: • 2nd intercostal space, left sternal border • Corresponds to the pulmonic valve • 2nd intercostal space, right sternal border • Corresponds to the aortic valve Anatomy & Physiology, 2e. p. 753, fig 19.2 and p. 259, fig. 7.32 https://openstax.org/books/anatomy-and-physiology-2e The Heart – Surface Anatomy 4th/5th intercostal space, right sternal border • Best place to hear sounds from the right ventricle and right AV valve 5th intercostal space, midclavicular line • **Best place to: • hear left AV valve and left ventricular sounds • Palpate the PMI ** In a person with a “normal” left ventricle Anatomy & Physiology, 2e. p. 753, fig 19.2 and p. 259, fig. 7.32 https://openstax.org/books/anatomy-and-physiology-2e Another View – Surface Anatomy The highlighted, coloured spots are where the sounds are “carried” for each valve • This picture is not very anatomically correct – the heart is very small • The apex (PMI) should be approximately at the 5th ICS, MCL • The right heart border (right atrium and vena cava) should not be so far to the right Anatomy & Physiology, 2e. p. 788, fig 19.30 https://openstax.org/books/anatomy-and-physiology-2e The Systemic Pressures And The Cardiac Cycle • The following pressure tracing shows: ▪ The aortic pressures – red ▪ The left ventricular pressures – green ▪ The left atrial pressures – yellow • These pressures are shown at the same time as the heart sounds that are caused by the: ▪ Closing of the atrioventricular valves (mitral valve on the left side) ▪ Closing of the semilunar valves (aortic valve on the left side) Systemic Pressures Anatomy & Physiology, 2e. p. 787, fig 19.29 https://openstax.org/books/anatomy-and-physiology-2e Systemic Pressures – the Left Atrium A – the left atrium (LA) contracts, helping fill the left ventricle (LV) B – the LV contracts 🡪 pressure increase causes the left AV valve to close 🡪 the first heart sound (Lub) C – The LA fills while the pressure in the LV is high A B C D E D – The pressure in the LV drops, resulting in opening of the left AV valve E – the LA fills Anatomy & Physiology, 2e. p. 787, fig 19.29 https://openstax.org/books/anatomy-and-physiology-2e Systemic Pressures – The Left Ventricle A – the relaxed LV experiences a “bump” in pressure as the LA fills it B – the LV contracts 🡪 pressure increase causes the left AV valve to close 🡪 the first heart sound (Lub) C – The LV relaxes, and pressure starts to drop A B C D E D – When the LV pressure is less than the LA pressure, the AV valve opens E – the LV fills Anatomy & Physiology, 2e. p. 787, fig 19.29 https://openstax.org/books/anatomy-and-physiology-2e Systemic Pressures – The Aorta A B C D A – diastolic pressure just prior to ventricular contraction B – the LV contracts 🡪 pressure increase overcomes aortic diastolic pressure 🡪 aortic valve opens C – The LV applies maximal (systolic) pressure to the aorta D – When the LV pressure is less than the aortic pressure, the aortic valve closes 🡪 second heart sound (Dub) Anatomy & Physiology, 2e. p. 787, fig 19.29 https://openstax.org/books/anatomy-and-physiology-2e Types of Heart Sounds It’s always normal to hear a valve closing\g. • AV valve 🡪 S1 🡪 “Lub” ▪ This is a lower frequency sound, because the valve itself is a bit bigger and more “floppy” ▪ Think of the largest string on a guitar • Semilunar valve 🡪 S2 🡪 “Dub” ▪ This is a higher frequency sound, because the valve itself is a bit smaller and “tighter” ▪ Think of the smallest string on a guitar • It’s uncommon to hear a valve opening ▪ Some pathologies that affect the cardiac valves can result in “opening” sounds – they’re usually called opening snaps Types of Heart Sounds Blood flow can be smooth and orderly • This is known as laminar flow, and this is normal in the heart Blood flow can be rapid, forming disorderly eddies and vibrations ▪ This is known as turbulent flow ▪ It is often caused by valvular abnormalities, and can cause a variety of sounds • Murmurs • Extra heart sounds (sometimes) ▪ It can be normal in some patients • Heart sounds are complex acoustical phenomena Types Of Valvular Abnormalities Stenosis – the valve doesn’t open widely enough • Higher pressures are needed to push blood through the narrow valve • The higher pressures cause “noisy” turbulent flow 🡪 a murmur • These murmurs are heard while blood is flowing across the valve… when the valve should be open. Anatomy & Physiology, 2e. p. 764, fig 19.12 https://openstax.org/books/anatomy-and-physiology-2e Types Of Valvular Abnormalities Stenosis – the valve doesn’t open widely enough • What would happen if the aortic valve in this picture “couldn’t” open widely enough? • Sometimes valves “scar” over time due to physical stresses 🡪 narrowing Types Of Valvular Abnormalities Regurgitation – the valve doesn’t close fully ▪ If the valve doesn’t close, then backflow occurs when the chamber before it relaxes ▪ This backflow causes a “noisy” turbulent flow 🡪 a murmur ▪ These murmurs are of course heard while blood is flowing across the valve… when the valve should be closed Types Of Valvular Abnormalities Regurgitation – the valve doesn’t close fully Damage to heart valves can make them unable to close fully Anatomy & Physiology, 2e. p. 766, fig 19.14 https://openstax.org/books/anatomy-and-physiology-2e • You can hear heart murmurs during ventricular systole or ventricular diastole ▪ If that murmur is due to a valve, it could be because the valve is damaged and either: • Can’t close • Can’t open fully • The location where the murmur is heard loudest and the phase of the cardiac cycle (ventricular systole or diastole) should allow you to deduce ▪ Which valve is involved ▪ Whether the valve is stenotic or regurgitating Location Murmur heard during ventricular diastole Murmur heard during ventricular systole 2nd intercostal space, right Aortic regurgitation sternal border Aortic stenosis 2nd intercostal space, left sternal border Pulmonic regurgitation Pulmonic stenosis 5th intercostal space, left sternal border L AV regurgitation L AV stenosis 5th intercostal space, midclavicular line R AV regurgitation R stenosis