IM Cardiology L.1.pdf

4th Internal Medicine Dr. Ahmed Moayed stage Lecture. 1 Cardiology INTRODUCTION TO CVS N...

4th Internal Medicine Dr. Ahmed Moayed stage Lecture. 1 Cardiology INTRODUCTION TO CVS Normally located in the middle and slightly to the left side of the thoracic cavity on the diaphragm between 3rd and 5th ribs. Weighs about 325 gm is males and about 275 gm in females Heart has 1. Base 2. Apex 3. Anterior 4. Posterior 1  It has: Four chambers 1. Right Atrium 2. Right Ventricle 3. Left atrium 4. Left ventricle Three layers 1. Outer Epicardium 2. Middle Myocardium 3. Inner Endocardium 4. And a covering Pericardium Pericardium: ❖ The pericardial sac has two layers: a serous layer and a fibrous layer. ❖ It encloses the pericardial cavity which contains pericardial fluid. ❖ The pericardium fixes the heart to the mediastinum, gives protection against infection, and provides the lubrication for the heart ❖ The pericardial sac normally contains up to 50 mL of fluid Epicardium: Outer most layer of the heart. Visceral layer of pericardium. 2 Myocardium: Thicker middle layer of the heart Composed of individual heart muscle cells called as cardiomyocytes. Joined together by intercalated disks Encased by collagen and other substances forming the extracellular matrix (INTERSTITIUM). Endocardium: Its cells are embryologically and biologically similar to the endothelial cells that line blood vessels. 3  Four valves: 1. Mitral valve 2. Aortic valve 3. Tricuspid valve 4. Pulmonic valve Mitral and tricuspid valves are called as ATRIO VENTRICULAR valves: Mitral valve has two leaflets. (Anterior and Posterior) Tricuspid valve has three leaflets (Anterior, Septal and Posterior) Aortic and Pulmonary valves are called as SEMILUNAR valves. Aortic valve has three cusps right coronary cusp, left coronary cusp And non coronary cusp. Pulmonic valve has three cusps. Two great arteries: 1. Aorta 2. Pulmonary artery 4 Coronary circulation : Cardiac output: CO = SV X HR For a resting adult: CO = 70mL/beat x75beats/min 5250mL/min 5.25 U/min 5 Stroke volume: Regulation of stroke volume is by three factors PRELOAD CONTRACTILITY AFTERLOAD Preload: Stretch of cardiac muscle prior to Contraction. Frank-starling law Preload is proportional to End Diastolic Volume: If HR is more than 160 beats/min stroke Volume declines due to short filling time. Contractility: It is the strength of contraction At any given preload. Positive and Negative Inotropics. Stimulation of sympathetic Division of ANS leads to positive Inotropic effect Inhibition of sympathetic Division of ANS leads to Negative inotropic effect Afterload: The pressure that must be overcome before a semilunar Valve can open is termed the afterload. Increase in afterload causes decrease in stroke volume HT and atherosclerosis increases the afterload. Sympathetic effect: Releases norepinephrine Parasympathetic Effect: Left Vagus nerve Releases acetylcholine Predominates during resting state Conduction system of the heart : 6 Cardiac auscultation Heart Sounds: Produced from blood turbulence caused by closing of the heart valves: S1 - atrioventricular valve closure LUB S2 - semilunar valve closure DUB S3 rapid ventricular filling S4 - atrial systole S3 is physiological less than 30 years of age. S4 is usually pathological. PRESENTING PROBLEMS IN CARDIOVASCULAR DISEASE: 7 1. Chest pain 2. SOB 3. Palpitation 4. Syncope 8 9 10 11