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CARDIOVASCULAR SYSTEM CARDIAC CYCLE HEART SOUNDS LECTURE – 4 DR. ZAHOOR ALI SHAIKH 2

HEART SOUNDS 3

There are four heart sounds SI, S2, S3 & S4. Two heart sound are audible with stethoscope S1 & S2 (Lub - Dub). S3 & S4 are not audible with stethoscope Under normal conditions because they are low frequency sounds. Ventricular Systole is between First and second Heart sound. Ventricular diastole is between Second and First heart sounds. 4

First heart sound (S1) It is produced due to the closure of Atrioventricular valves (Mitral & Tricuspid) It occurs at the beginning of the systole and sounds like LUB Frequency:50-60 Hz Time: 0.15 sec 5

Second heart sound (S2) It is produced due to the closure of Semilunar valves (Aortic & Pulmonary) It occurs at the end of the systole and sounds like DUB Frequency:80-90 Hz [ High pitch ] Time: 0.12 sec It is short and sharp 6

HEART SOUNDS Important Sounds are caused by vibrations set within the wall of the ventricles and major arteries during valve closure. Opening of the valve does not cause sound. 7

Third heart sound (S3) It occurs at the beginning of middle third of Diastole Cause of third heart sound – Rush of blood from Atria to Ventricle during rapid filling phase of Cardiac Cycle. It causes vibration in the blood Frequency:20-30 Htz Time: 0.1 sec 8

Fourth heart sound (S4) or Atrial Sound It occurs at the last one third of Diastole (just before S1) Cause of Fourth heart sound – Due to Atrial contraction which causes rapid flow of blood from Atria to Ventricle and vibration in the blood. Frequency: < 20 Htz Note: Third and Fourth heart sound are low pitched sounds therefore not audible normally with stethoscope S3 may be heard in children and young adults but usually pathological in old age 9

ADAS VSVD EVENTS HEART SOUNDS 0.7 Sec. 0.1 sec. 0.3Sec.0.5 sec. 1 st Heart Sound 2 nd Heart Sound3 rd Heart Sound4 th Heart Sound AS – Atrial Systole; AD – Atrial Diastole ; VS – Ventricular systole; VD – Ventricular diastole 10

11 Aortic Area – 2 nd right Intercostal space at the right sternal border Pulmonary Area – 2 nd left Intercostal space at the left sternal border Mitral Area – 5 th left Intercostal space 1cm inside mid – clavicular line [Apex beat area] Tricuspid Area – Left side of lower sternum

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Heart Murmurs Murmurs are abnormal sounds produced due to abnormal flow of blood [turbulent blood flow] through abnormal heart valves e.g.. stenosis or incompetence. Stenosis means narrow or stiff, valve that does not open completely. Incompetent means valve which does not close properly and remains open. 13

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Heat Murmurs When blood is forced through stenotic valve, it produces an abnormal whistling sound. When blood flows backward through incompetent valve, it produces swishing or gurgling murmur sound. Most common cause of stenosis and incompetent valve is Rheumatic fever, an auto immune disease triggered by Streptococcus bacterial infection. 15

Heat Murmurs Systolic murmur are produced during the systole of the ventricle, between 1 st and 2 nd heart sound (Lub – Murmer – Dup). Diastolic murmur are produced during the diastole of the ventricle, between 2 nd and 1 st heart sound (Lub – Dup – Murmer – Lub). During aortic stenosis and mitral incompetence – systolic murmur. Aortic incompetence and Mitral Stenosis – diastolic murmur. 16

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19 We will discuss 1.PRESSURE VOLUME LOOP 2. EVENTS OF CARDIAC CYCLE

Relationship between Lt. ventricular volume & pressure changes 20

Events of cardiac cycle for Lt. ventricular function showing changes in Lt. atrial pressure, Lt. ventricular pressure, aortic pressure, ventricular volume, ECG & phonocardiogram 21

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WHAT YOU SHOULD KNOW FROM THIS LECTURE? Functions of A-V vales & Semilunar valves. Functions of papillary muscles. There are four heart sounds : S 1, S 2, S 3, & S 4. Audible with stethoscope are only S 1 (Lub) & S 2 (Dub / Dup) 23

Places to be auscultated on the chest for heart sounds i.e. Aortic, pulmonary, Mitral & tricuspid area. Murmurs (abnormal heart sounds). Pressure – Volume Low Cardiac Cycle Diagram [Phases, Pressure, Volume, and Heart Sounds] 24

THANK YOU 25