L19 - Cardiovascular System PDF

L19- CARDIOVASCULAR SYSTEM DR. PUGAZHANDHI BAKTHAVATCHALAM, ASSISTANT PROFESSOR OF ANATOMY AND PHYSIOLOGY, AUACAS, AUA LEARNING OUTCOMES Blood supply of the heart and its significance - Describe the coronary arteries and cardiac veins. Innervation of the heart - Desc...

L19- CARDIOVASCULAR SYSTEM DR. PUGAZHANDHI BAKTHAVATCHALAM, ASSISTANT PROFESSOR OF ANATOMY AND PHYSIOLOGY, AUACAS, AUA LEARNING OUTCOMES Blood supply of the heart and its significance - Describe the coronary arteries and cardiac veins. Innervation of the heart - Describe the nerves supplying the heart  Arterial supply of Heart The arterial supply of the heart is provided by the right and left coronary arteries, which arise from the ascending aorta immediately above the aortic valve. The coronary arteries and their major branches are distributed over the surface of the heart, lying within subepicardial connective tissue. 23-Sep-24 3 Arterial Supply Heart (Sternocostal surface) Ascending Aorta Right Auricle Left coronary artery Pulmonary trunk Right coronary artery 23-Sep-24 4  Right Coronary Artery Origin: Branch of ascending aorta begins from the anterior aortic (right coronary) sinus. Course: Runs between the right auricle and pulmonary trunk, enters the anterior part of coronary sulcus, runs to the right in the anterior part of coronary sulcus winds around the right margin of heart, then runs to the left in the posterior part of coronary sulcus. Termination: Anastomoses with circumflex branch of left coronary artery in the posterior part of coronary sulcus. 23-Sep-24 5  Arterial Supply Base and Diaphragmatic Surface of Heart Left atrium Left circumflex artery Right atrium Right coronary artery Left ventricle Right ventricle 23-Sep-24 6 Right Coronary Artery Branches: Right conus branch - supplies lower part of pulmonary trunk and upper part of right ventricle. Atrial branches - supply right atrium, one of them supply SA node (artery of SA node). Ventricular branches - supply right ventricle. Right marginal artery - one of the ventricular branch, runs along the inferior margin of heart. Posterior inter-ventricular branch (posterior descending)- runs in the posterior inter-ventricular groove 23-Sep-24 7  Right Coronary Artery-Branches (Sternocostal Surface) Atrial Branches Right marginal artery Right Conus Artery Ventricular branches 23-Sep-24 8 Right Coronary Artery Area of distribution of right coronary artery: Right atrium. Right ventricle except a part on the sternocostal surface near the anterior inter-ventricular groove. Part of the left ventricle on the inferior surface near the posterior inter-ventricular groove. Posterior part of inter-ventricular septum. Most of the conducting system of heart (SA node, AV node, right AV bundle) except left AV bundle. 23-Sep-24 9  Left Coronary Artery Origin: Arises from the ascending aorta - left posterior aortic sinus. Course: Runs between the left auricle and pulmonary trunk reaches the anterior part of coronary sulcus and terminates by dividing to 2 branches. Termination: Divides into anterior inter- ventricular and circumflex branches 23-Sep-24 10 Left Coronary Artery (Sternocostal Surface) Ascending aorta Left coronary artery Circumflex coronary Pulmonary trunk Anterior interventricular Right coronary artery 23-Sep-24 11  Left Coronary artery (Branches) 1. Anterior interventricular (anterior descending) branch: LAD: Arises from left coronary artery runs on the sternocostal surface in the anterior inter-ventricular groove with the great cardiac vein terminates by anastomosing with posterior inter-ventricular artery near the apex. Branches: Left conus artery – supplies upper part of right ventricle and lower part of pulmonary trunk. Ventricular branches – supply the left ventricle and part of right ventricle near the anterior inter- ventricular groove. One of the ventricular branch is large and is known as left diagonal artery. Septal branches – supply anterior part of inter- ventricular septum. 23-Sep-24 12  Left coronary artery (Branches) 2. Circumflex artery: Arises from left coronary artery curves around the left margin of heart in the coronary sulcus. Enters the posterior part of coronary sulcus and terminates by anastomosing with right coronary artery. Branches: Atrial branches – supply left atrium. Ventricular branches – supply left ventricle. Left marginal artery – runs along the left margin of heart, supplies left ventricle. 23-Sep-24 13 Left coronary artery Area of distribution of left coronary artery: Left atrium. Left ventricle except a part on the diaphragmatic surface near the posterior interventricular groove. Part right ventricle on the anterior surface near the anterior interventricular groove. Anterior part of interventricular septum. Left AV bundle. 23-Sep-24 14 Arterial supply of conducting system The sinuatrial node is usually supplied by the right but sometimes by the left coronary artery. The atrioventricular node and the atrioventricular bundle are supplied by the right coronary artery. The right bundle branch of the atrioventricular bundle is supplied by the right coronary artery. The left bundle branch is supplied by the left coronary artery. 23-Sep-24 15 Clinical importance of coronary artery Coronary artery anastomosis- Anastomoses between the terminal branches of the right and left coronary arteries (collateral circulation) exist, but they are usually not large enough to provide an adequate blood supply to the cardiac muscle if one of the large branches become blocked by disease. A sudden block of one of the larger branches of either coronary artery usually leads to myocardial death (myocardial infarction), although sometimes the collateral circulation is enough to sustain the muscle. 23-Sep-24 16  Coronary artery diseases A sudden block of one of the large branches of either coronary artery will usually lead to necrosis of the cardiac muscle (myocardial infarction). Coronary artery blockage are caused by an acute thrombosis on top of a chronic atherosclerotic narrowing of the lumen. Arteriosclerotic disease of the coronary arteries may present in three ways, depending on the rate of narrowing of the lumen of the arteries: 1. General degeneration and fibrosis of the myocardium occur over many years and are caused by a gradual narrowing of the coronary arteries. 2. Angina pectoris is cardiac pain that occurs on exertion and is relieved by rest. In this condition, the coronary arteries are so narrowed that myocardial ischemia occurs on exertion but not at rest. 3. Myocardial infarction occurs when coronary flow is suddenly reduced or stopped and the cardiac muscle undergoes necrosis 23-Sep-24 17  Coronary disease management Coronary angioplasty, coronary artery stenting and coronary by pass surgery are used for treating coronary artery disease. Coronary angioplasty : A catheter is inserted into the femoral artery in the thigh, passed through external and common iliac arteries and into the aorta to the origins of the coronary arteries. A fine wire is then passed into the coronary artery and is used to cross the stenosis. A balloon is then passed over the wire and inflated at the level of the obstruction, thus widening it. 23-Sep-24 18  Coronary artery management Coronary stent : Coronary stent is stainless tube with slots. It is mounted on a balloon catheter in a "crimped" or collapsed state. When the balloon is inflated, the stent expands or opens up and pushes itself against the inner wall of the coronary artery and the blood flow is maintained. 23-Sep-24 19 Coronary artery management Coronary artery bypass grafting (CABG) : If the coronary artery disease is too severe and not treated by coronary angioplasty, surgical bypass grafting is done. The great saphenous vein in the lower limb is harvested and used as an autologous graft, which is used to bypass blocked part of the coronary arteries. The internal thoracic or radial arteries can also be used for this purpose. 23-Sep-24 20  Venous Drainage of Heart Venous blood from the heart is drained by- 1.Coronary sinus and its tributaries. 2. Anterior cardiac vein. 3. Thebesian veins (venae cordis minimi). 23-Sep-24 21  Venous drainage Coronary sinus: Largest vein of heart, about 3 cm long. Formed by the union of great cardiac vein and oblique vein of left atrium. Situated in the posterior part of coronary sulcus between the left atrium and left ventricle. Terminates by opening into the smooth part of right atrium. Opening is guarded by valve of coronary sinus (Thebasian valve). Tributaries: 1. Great cardiac vein 2. Small cardiac vein 3. Middle cardiac vein 4. Posterior vein of left ventricle 5. Oblique vein of left atrium. 23-Sep-24 22 Venous Drainage (Coronary Sinus) (Sternocostal Surface) Left Coronary artery Anterior cardiac vein Great cardiac vein Small cardiac vein 23-Sep-24 23  Venous drainage (Coronary Sinus) Diaphragmatic Surface Left Atrium Oblique vein of left atrium Great Cardiac vein Right Atrium Coronary Sinus Posterior vein Small cardiac vein of left ventricle Middle cardiac vein Left Ventricle Right Ventricle 23-Sep-24 24  Coronary Sinus Tributaries: 1. Great cardiac vein: Situated in the anterior interventricular groove and anterior part of coronary sulcus. 2. Small cardiac vein: Situated in the posterior part of coronary sulcus between right atrium and right ventricle. 3. Middle cardiac vein: Situated in the posterior inter-ventricular groove. 4. Posterior vein of left ventricle: Situated in the diaphragmatic surface of left ventricle. 5. Oblique vein of left atrium (of Marshall): Situated in the posterior surface of left atrium. 23-Sep-24 25  Venous Drainage Anterior cardiac veins: 3 to 4 veins situated on the sternocostal surface of right ventricle. Terminate by opening into the right atrium. Thebasian veins (venae cordis minimae): Small veins situated in the myocardium of all the chambers. Terminate by opening into all chambers. 23-Sep-24 26  Nerve Supply of Heart Heart is supplied by nerves arising from superficial and deep cardiac plexus. Nerves arising from these plexuses run along the coronary arteries and supply the heart. These contain sympathetic and parasympathetic nerves. Sympathetic nerves are derived from upper 4 or 5 thoracic segments (T1-T4) of spinal cord. They are cardio-acceleratory and on stimulation increase heart rate and dilate coronary arteries. Parasympathetic nerves are derived from vagus(X) which arise from the dorsal nucleus of vagus (medulla oblongata),are cardio- inhibitory and on stimulation slow down the heart rate and constrict coronary arteries. 23-Sep-24 27  Superficial Cardiac Plexus Situated below the arch of aorta. Formed by: Sympathetic - Superior cervical cardiac branch of left sympathetic chain. Parasympathetic -Inferior cervical cardiac branch of left vagus nerve. 23-Sep-24 28  Deep cardiac Plexus Situated in front of bifurcation of trachea and behind the arch of aorta. Formed by: Sympathetic - cardiac branches derived from cervical and upper thoracic ganglia of sympathetic chain except cardiac branch of left superior cervical sympathetic ganglia. Parasympathetic - cardiac branches of vagus and recurrent laryngeal nerves except inferior cervical cardiac branch of left vagus 23-Sep-24 29 Reference Moore, Clinically Oriented Anatomy, 6th Edition, 2009, Lippincott Williams & Wilkins. Standring, Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 40thEdition, 2008. Drake R.L. Gray’s Anatomy for Students, 2nd Edition, 2010, Elsevier, ISBN 9780808924067. 23-Sep-24 30