Submitted by: TREASA JAMES 2015 BATCH

PURPOSE CORONARY CIRCULATION introduction Arterial supply Venous drainage Lymphatic drainage Innervation of heart Special features

Introduction Coronary circulation: It’s the circulation of blood in the blood vessels of the heart muscle (myocardium). The vessels that deliver oxygen-rich blood to the myocardium are the coronary arteries. The vessels that remove the deoxygenated blood from heart are known as cardiac veins.

Arterial supply The heart is supplied mostly by 2 coronary arteries , which arise from the ascending aorta immediately above the aortic valve. Coronary arteries are vasa vasorum of ascending aorta.

RIGHT CORONARY ARTERY Origin: Anterior aortic sinus of the ascending aorta Course: Arising from the ascending aorta First runs b/n pulmonary trunk and the right auricle Descends almost vertically in right AV groove Upto the junction of right and inferior border of heart At the inferior border, it turns posteriorly and runs in posterior AV groove upto the posterior interventricular groove Terminates by anastomosing with left coronary artery

Branches and Distribution 1) Right conus artery:- supplies anterior surface of pulmonary conus 2) Atrial branches: supply atria One of the atrial branches artery of sinuatrial node supplies SA node. 3) Anterior ventricular branches: supply anterior surface of right ventricle Marginal branch is largest and runs along lower marginal sternocostal surface to reach apex. 4) Posterior ventricular branches: supply diaphragmatic surface of right ventricle. 5) Posterior interventricular artery: supplies Posterior part of IV septum AV node Right and left ventricle

LEFT CORONARY ARTERY Origin: left posterior aortic sinus of ascending aorta Course: Arising from ascending aorta Artery runs forwards and to the left b/n the pulmonary trunk and the left auricle Divides into anterior interventricular and circumflex artery

Anterior interventricular artery Circumflex artery Runs downward in anterior IV groove winds around the left margin to apex of heart of heart Pass posteriorly around of the apex continue in left posterior Of heart coronary sulcus upto Enter posterior IV groove posterior IV groove Terminate by anastomosing with posterior Interventricular artery anastomose with right coronary artery

Branches and Distribution Anterior interventricular artery: supplies (a)anterior part of IV septum (b) left ventricle and part of right (c) left bundle branch (His) 2) Circumflex artery: gives left marginal artery and supplies left margin of left ventricle upto apex of heart 3)Diagonal artery : arise directly from trunk of left coronary artery 4)Conus artery: supplies pulmonary conus 5)Atrial branches: supply left atrium

Coronary Dominance In right coronary dominance, the posterior interventricular artery is a branch of the right coronary artery. Its found in 90% individuals. In left coronary dominance, the posterior interventricular artery arises from circumflex branch of the left coronary artery. Its found in 10% individuals. Anastomosis of coronary arteries Anastomosis exist b/n terminal branches of the coronary arteries at the arteriolar level(collateral circulation) If any occlusion occurs there is time for healthy arterioles to open up and and collateral circulation is established. But if sudden occlusion occurs the arterioles do not get time to open up to provide collateral circulation.

VENOUS DRAINAGE Venous blood from heart is drained into right atrium by : 1)Coronary sinus 2)Anterior cardiac vein 3)Venae cordis minimae(Thebesian veins) Coronary sinus: Its the principal vein of heart . Most of venous blood from the walls of the heart is drained into the right atrium through coronary sinus. Largest vein of heart and lies posterior part of AV groove. Develops from left horn of sinus venosis and a part of left common cardinal vein.

TRIBUTARIES Great cardiac vein : accompanies anterior interventricular artery and circumflex artery middle cardiac vein: accompanies posterior interventricular artery Small cardiac vein: accompanies right ventricular artery Posterior vein of left ventricle : runs on diaphragmatic surface of left ventricle and joins sinus of to the elft of middle cardiac vein. Oblique vein of left atrium: runs downward on posterior surface of left atrium to enter left end of the coronary sinus Anterior cardiac vein: series of small vein run parallel to each other Venae cordis minimae : these are extremely small veins in walls of all gthe four chambers of the heart.

Lymphatic drainage of heart Lymphatics of heart accompany the coronary arteries , emerge from the fibrous pericardium along with the ascending aorta and pulmonary trunk in form of 2 trunks. The right trunk drains into brachiocephalic nodes and left trunk drains into tracheobronchial nodes.

Innervation of coronary blood vessels Sympathetic innervation: causes coronary vasodilatation as coronary arteries are rich in alpha receptors. Parasympathetic innervation: cause vasodialatation which is mediated via cholinergic receptors.

SPECIAL FEATURES OF CORONARY CIRCULATION PHASIC FLOW: Coronary blood flow decrease during systole and increase during diastole. AUTOREGULATION: The metabolic regulation of coronary circulation is well developed. Coronary blood flow is adjusted according to need of myocardium. The coronary arteries are end arteries. Blockage of coronary arteries results in ischemia and infarction of the cardiac muscles supplied by artery.

OXYGEN EXTRACTION: Coronary blood flow can be increased four to five folds to meet the heart’s more oxygen need during exercise. Thus, adequate coronary blood flow reserve. METABOLISM: The heart utilizes wide varities of substrates for its metabolism like free faty acids , glucose, pyruvate,lactate. Major source of energy supply is free fatty acids. Heart muscle extracts about 80% of the oxygen from the arterial blood. Thus arteriovenous oxygen difference is very high even at rest.

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