L 43 Coronary Circulation PDF

L 43 Blood Supply of Heart ILOs By the end of this lecture, students will be able to 1. Correlate the origin of both coronary arteries to the sinuses of the ascending aorta. 2. Relate the different grooves on the heart surfaces to the coronary vessels & their branches passing through. 3. Appraise th...

L 43 Blood Supply of Heart ILOs By the end of this lecture, students will be able to 1. Correlate the origin of both coronary arteries to the sinuses of the ascending aorta. 2. Relate the different grooves on the heart surfaces to the coronary vessels & their branches passing through. 3. Appraise the distribution of branches of both coronary arteries in relevance to different heart chambers and structures. 4. Apply the anatomical distribution of coronary arteries to interpret the clinical condition of ischemic heart disease. 5. Differentiate between the different veins draining the heart in relevance to their termination. - Two coronary arteries arise from the aortic sinuses of the ascending aorta and supply the heart. They circle the heart in the coronary sulcus. The venous return passes through cardiac veins, most of which empty into the coronary sinus. Coronary sinus is located in the coronary sulcus on the posterior surface of the heart between the left atrium and left ventricle. The coronary sinus empties into the right atrium between the opening of the inferior vena cava and the right atrioventricular orifice. Arterial supply: The heart receives arterial blood through right and left coronary arteries. (crown like arrangement) 1- Right coronary artery: Origin: It originates from the anterior superior aortic sinus of the ascending aorta. Course: It passes to the right between the right auricle and the pulmonary trunk and then descends vertically in the coronary sulcus, between the right atrium and right ventricle till the lower borders of the heart. On reaching the lower border of the heart, it turns posteriorly and continues in the sulcus onto the diaphragmatic surface and base of the heart. Branches: 1- Artery of S.A. node: In 60% of population and in 40% it arises from circumflex artery (left coronary). 2- branch to AV node in 90% of population. 3- marginal branches: supply both surfaces of right ventricle. 4- right posterior descending (Posterior interventricular artery): It runs in the posterior interventricular groove. It supplies inferior aspect of RV, LV, interventricular septum and posterior papillary muscle. 1 Coronary arteries Branches of coronary arteries Clinical correlation: Damage to vessels supplying portions of the conducting system leads to specific defects. (myocardial infarction) Sick sinus syndrome (tachy-brady syndrome): Due to damage to sinus nodal artery where frequency of generation of cardiac action potentials becomes randomly or inappropriate. Damage to artery supplying AV node or bundle of His leads to complete heart block. 2 Branches of right coronary artery (back of heart) Left coronary artery: Origin: It originates from the left posterior aortic sinus of the ascending aorta. Course: It passes between the pulmonary trunk and the left auricle before entering the coronary sulcus. It is short, about 2 cm long, and ends by dividing into two branches: 1- Circumflex Branch 2- left anterior descending artery (LAD) (Anterior Interventricular A) Branches: 1- Circumflex artery: It runs in the posterior atrio-ventricular groove. It gives off marginal branches and obtuse marginal. It ends by anastomosing with the right coronary artery. 2- Left Anterior Descending artery (LAD): (Anterior interventricular artery) It runs in the anterior interventricular groove to the apex then posterior interventricular groove. It ends by anastomosing with the termination of posterior interventricular artery. During its course it supplies: The anterior septal , anterior lateral and apical portion of the left ventricle and the anterior papillary muscle. N.B. The distribution pattern of the left coronary artery enables it to supply most of the left atrium and left ventricle, and most of the interventricular septum, including the atrioventricular bundle and its branches. Variation of coronary arteries branches: Right dominance: It’s the commonest (70%). Posterior inter ventricular artery originates from right coronary artery. Left dominance: 3 It’s the least common (20%). Posterior interventricular artery originates from the circumflex artery. Variations of branches of coronary arteries Venous Drainage: Venous drainage of the heart is through: 1- Coronary sinus 2- Anterior Cardiac veins 3- Thebesian veins (Venae Cordis Minimae) 1- Coronary sinus: It is a wide vein that lies between the left atrium and the left ventricle posteriorly. It receives most of the veins from the heart and then opens into the right atrium. Tributaries: 1. Great Cardiac Vein: This vein lies in the anterior interventricular groove. 2. Middle Cardiac Vein: This vein lies in the posterior interventricular groove. 3. Small Cardiac Vein: This vein runs along the lower border of the heart from left to the right. 4. Oblique vein of the left Atrium: It is a small vein which descends obliquely on the back of left atrium to join the coronary sinus. 5. Posterior vein of the left ventricle: It ascends on the back of left ventricle to join the coronary sinus. 2- Anterior Cardiac Veins: One or two veins from the front of the right ventricle and open directly into the right atrium. 3- Thebesian veins (Venae Cordis Minimae): They are small veins that begin in the myocardium and open directly into the right atrium and right ventricle. Clinical correlation: An imbalance between the oxygen demands of the heart and amount supplied by coronary blood supply leads to the development an anoxic pain originating in the heart which is called angina. 4 Coronary sinus and its tributaries on: (A) front (B) back of the heart 5 Oblique vein of left atrium and posterior vein of left ventricle on the back of the heart Anterior cardiac veins 6 7