Heart & Pericardium PDF

Heart & Pericardium Pericardium Closed sac External layer: Fibrous pericardium Internal layer: Serous pericardium Serous pericardium: Parietal layer Visceral layer (...

Heart & Pericardium Pericardium Closed sac External layer: Fibrous pericardium Internal layer: Serous pericardium Serous pericardium: Parietal layer Visceral layer (epicardium) Fibrous Pericardium fused with the tunica adventitia of great vessels sternopericardial ligaments pericardiophrenic lig by loose connective tissue Pericardium The heart & roots of the great vessels within the pericardial sac The heart and pericardial sac are located Function of the fibrous pericardium Pericardial Cavity is the potential space fluid Serous Pericardium Visseral layer of serous pericardium  epicardium The reflection of the pericardium during the folding of the embryonic heart results in recesses Oblique sinus Transverse sinus Transverse Pericardial Sinus Aorta and Pulmonary trunk leave the heart SVC, IVC and Pulmonary veins enter the heart Surgical Significance of the Transverse Pericardial Sinus After the pericardial sac is opened anteriorly Oblique Pericardial Sinus located behind the left atrium, between the 4 pulmonary veins, SVC and IVC Arterial Supply of the Pericardium 1. Pericardiacophrenic artery 2. Musculophrenic artery 3. Pericardial branches from; bronchial, oesophageal, superior phrenic arteries 4. Visceral layer of serous pericardium (epicardium) is supplied by coronary arteries Nerve supply and venous drainage of pericardium Veins Azygos system Pericardiacophrenic veins Nerves Phrenic nerves (C3-C5) Vagus nerves Sympathetic trunks Phrenic Nerve (C3-C5) Ipsilateral supraclavicular region (top of the shoulder of the same side) Clinical note Pericarditis: inflammation of the pericardium Cardiac tamponade (Heart compression) Extensive pericardial effusion causes the compression of heart which prevents the movement of heart especially expansion of the ventricles because fibrous pericardium is inelastic. Circulation fails therefore It is lethal condition. Paracentesis of pericardium: Drainage of fluid from the pericardial cavity Location of Heart Larger than a fist Middle mediastinum Mediastinum is between the two pulmonary cavities Location of the heart HEART Chambers of the heart  Cardiac cyle Right and left Atrioventricular pumbs Elongation and filling (diastole) Shortening and emptying (systole) Left AV orifice Right AV orifice Two Heart Sounds First sound is a lub Secound sound is dub The wall of each heart chamber From internal to external: Endocardium: membrane of the heart Myocardium: is the contractile layer of the heart Epicardium: visceral layer of serous pericardium Arrangement of the myocardium Fibrous Skeleton of Heart Fibrous rings Fibrous trigones Right fibrous trigone: aortic ring & right atrioventricular ring Left fibrous trigone: aortic ring & left atrioventricular ring Coronary Sulcus (atrioventricular groove) right coronary artery circumflex branch of left.. coronary sinus small cardiac vein Anterior interventricular sulcus anterior interventricular artery (left anterior descending artery: LAD) great cardiac vein Posterior interventricular sulcus posterior interventricular artery (posterior descending a) middle cardiac vein Shape of the heart Apex of the heart Left ventricle Left 5th intercostal space Apex beat Base of the Heart left atrium bodies of vertebrae T6-T9 The four surfaces of the heart Anterior (sternocostal) surface: right ventricle Diaphragmatic (inferior) surface: left ventricle, right ventricle Right pulmonary surface: right atrium Left pulmonary surface: left ventricle The four borders of the are Right border: right atrium Inferior border: right ventricle, left ventricle Left border: left ventricle, left auricle Superior border: right and left atria and auricles Projection of the heart Superior left angle: 3 cm left of the mid-plane, at the 2nd costal cartilage Inferior left angle: 7-9 cm left from the mid-line, at the 5th intercostal space Superior right angle: 2 cm right of the mid-plane, at the 3rd costal cartilage Inferior right angle: 2 cm right of the mid plane, at the 6th costal cartilage Radiological evaluations  Chambers of the heart Two atria Right atrium Left atrium -------------------------------------------------------------------------------- Two ventricles Right ventricle Left ventricle 33 Right Atrium sinus of venarum: –smooth –thin walls –receives both venae cavae Right auricle: –walls are covered by the: pectinati muscles.  Right atrium Right auricle sulcus terminalis (terminal groove) crista terminalis (terminal crest Right atrium Right auricle: conical muscular pouch Anterior wall: pectinate muscles Right Atrium Valve of coronary sinus (Thebesian valve) Right atrium valve of IVC (Eustachian valve) during development the valve of IVC Right atrium Oval fossa: on the interatrial septum Right atrium interatrial septum –fossa ovalis (oval fossa) –limbus fossa ovalis Outflow of the right atrium Right atrioventricular orifice Tricuspid valve (anterior, posterior & septal cusps) Congenital Heart Diseases: Atrial Septal Defect (ASD) Incomplete closure of the oval foramen causes the ASD. Large ASD permit oxygenated blood from the lungs, from the left atrium through the ASD in to the right atrium (from left to right shunt), causing enlargement of the right atrium and ventricle and dilatation of the pulmonary trunk. Resulting in hypertrophy of the right atrium and ventricle and pulmonary arteries Right ventricle Right ventricle Conus arteriosus (infundibulum) Pulmonary orifice Trabeculae carneae Supraventricular crest Inflow part of the right ventricle Right atrioventricular orifice Tricuspid valve (anterior, posterior & septal cusps) Located posterior to the body of the sternum at the level of the 4th and 5th intercostal spaces Bases of the cusps Right ventricle Tendinous cords (chordae tendineae) Papillary muscles Anterior Posterior Septal Prevented from prolapsing (being driven into the right atrium Regurgitation of blood (backward flow of blood) Papillary muscles in the right ventricle Anterior papillary muscle: ant & post cusp Posterior papillary muscle: post & septal cusp Septal papillary muscle: ant & septal cusp Clinical Note Necrosis of the papillary muscle may result in prolapse of related valve Importance of the Anterior papillary Muscle septomarginal trabecula (moderator band) Right crus of the AV bundle (right bundle branch) Septomarginal trabecula (Moderator band) Right crus of the AV bundle (right bundle branch)  Interventricular septum (IVS) Muscular part Membraneous part - Superiorly and posteriorly -septal cusp is attached to the middle of the membraneous part of IVS Ventricular Septal Defect (VSD) Membraneous and muscular parts of the interventricular septum develop in different times. Therefore membraneous part is the common site of ventricular septal defect. Because the blood pressure in the left ventricle is higher than the that of the right ventricle, the blood enter right ventricle by passing through the this defect. This condition causes right ventricular hypertrophy and pulmonary arterial hypertension. Outflow of the right ventricle Pulmonary valve Ant semilunar cusp Right semilunar cusp Left semilunar cusp left 3rd costal cartilage Left atrium Left Atrium has two parts: posterior part inflow portion smooth walls anterior part is continous with the left auricle pectinati muscles Left atrium Left auricle: muscular pouch Interatrial septum Left atrium Outflow part: Left AV orifice Mitral (Bicuspid) Valve Posterior to the sternum at the level of the 4th costal cartilage Left ventricle Left Ventricle Trabeculae carneae Papillary muscles (ant & post) Tendinous cords Outflow part of the left ventricle- Aortic vestibule Aortic valve:posterior, right and left semilunar cusps Posterior to the left side of the sternum at the level of the 3rd intercostal space Auscultation Areas Semilunar Valves Superior to the each semilunar cusp, the walls of the orgins of the vessels are dilated sinus Myocardial Bridge Right Coronary Artery RCA  SA nodal branch Right Marginal artery RCA AV nodal branch Posterior interventricular artery (Posterior descending artery) (PDA)  Right coronary artery Right atrium Right ventricle SA node AV node interatrial septum a portion of left atrium posterior 1/3 of the interventricular septum a portion of the posterior part of left ventricle Left coronary artery Anterior interventricular artery ( Left Anterior Descending) LAD (1 or 2) diagonal branch Circumflex artery left marginal artery LAD Diagonal artery  Left coronary artery left atrium left ventricle anterior 2/3 of the interventricular septum AV bundle and its branches Coronary Collateral Circulation Arteries that supply regions of the myocardium lacking sufficient anastomoses from other large branches. Veins of the heart Great cardiac vein Middle cardiac vein Small cardiac vein Left posterior ventricular v &left marginal vein Oblique vein of left atrium (vein of Marshall) Smallest cardiac vein (venae cordis minimae or veins of Thebesius) Anterior cardiac veins Veins of the heart  Conducting system of the heart generates and transmits the impulses consists of nodal tissue & conducting fibers Sino-atrial node Atrio-ventricular node Atrioventricular Bundle (His bundle) Right and left bundle branches Purkinje fibers SA node (Keith-Flack node) small collection of nodal tissue specialized cardiac m fibers associated fibroelastic connective tissue pace maker AV node (Aschoff-Tawara) myogenic conduction The AV node  the AV bundle (bundle of His) AV Bundle  Autonomic Innervation of the heart Parasympathatic preganglionic fibers Dorsal nucleus of vagus nerve Sympathatic postganglionic fibers cervical and upper thoracic parts of the sympathetic trunks Sympathetic postganglionic fibers Cardiac plexus SA, AV, on cardiac muscle fibers and on coronary arteries Activation of these nerves results in cardiac acceleration, increased force of contraction of cardiac muscle and dilatation of coronary arteries. The coronary dilatation is mainly produced in response to local metobolic needs rather than by direct nerve stimulation. Preganglionic parasympathetic fibers Descend in the vagus nerve Cardiac plexus SA, AV and coronary arteries. Activation of these nerves results in a reduction in the rate and force of contraction of the myocardium and the constriction of the coronary arteries Here again, the coronary constriction is mainly produced by the reduction in local metabolic needs rather than by neural effects. Pain due to cardiac ischemia The pain is often referred to the cutaneous region supplied by the same spinal cord levels