Coronary Circulation Students PDF

Coronary Circulation Dr. Rana Aly Elbeshbeishy Professor, Anatomy Department, RAKCOMS, RAKMHSU MBBS, MSc, PhD (Anatomy), Faculty of Medicine, ASU, Egypt MHPE Ottawa U, Canada [email protected] Office- 209, First Floor, Ext. 262 Learning Ou...

Coronary Circulation Dr. Rana Aly Elbeshbeishy Professor, Anatomy Department, RAKCOMS, RAKMHSU MBBS, MSc, PhD (Anatomy), Faculty of Medicine, ASU, Egypt MHPE Ottawa U, Canada [email protected] Office- 209, First Floor, Ext. 262 Learning Outcomes -Locate and describe the branches of each coronary artery and areas they supply; explain the concept of dominance. -List and locate the coronary veins and describe their drainage. - Clinical correlations  Right Coronary Artery 9 0 0 RCA 1m posteriorinterven arters RCA I'VE Origin: from Ascending aorta (right aortic sinus). Emerges between right auricle & pulmonary trunk, then runs downward in coronary sulcus till… and continues posteriorly in the same groove till it anastomoses with Circumflex branch of left coronary artery.  Right Coronary Artery 1 RCA 3 2 RCA branches: 1. Artery to SA Node & AV Node (RCA supplies them in ~60% of patients) same 2. Posterior descending artery (PDA) or Posterior Interventricular A.: the largest branch (RCA supplies this artery in ~70% of patients) 3. Right Marginal Artery  Left Coronary Artery LCA 2 1 Origin : from Ascending aorta (left aortic sinus). Emerges between left auricle & pulmonary trunk, then runs in coronary sulcus & divides into Anterior interventricular (1) & Circumflex arteries (2). Circumflex artery continues in coronary sulcus to the back of heart & anastomoses with terminal part of right coronary artery.  Left Coronary Artery LCA 2 1 3 LCA branches: 1. Left Anterior Descending Artery (LAD) or Anterior Interventricular A. 2. Circumflex Artery (can supply SA node, AV node or PDA in minority of patients) 3. Left Marginal Artery branch from Circumflex artery A 65-year-old man was admitted to the emergency room with severe central chest pain that radiated to the neck and predominantly to the left arm. He was overweight and a known heavy smoker. On examination he appeared gray and sweaty. His blood pressure was 74/40 mm Hg (normal range 120/80 mm Hg). An electrocardiogram (ECG) was performed and demonstrated anterior myocardial infarction. An urgent echocardiograph demonstrated poor left ventricular function. The cardiac angiogram revealed an occluded vessel A. Normal left coronary artery angiogram. B. Left coronary artery angiogram showing decreased flow due to blockages Clinical Anatomy: Coronary blockage most likely to occur in LAD (~40- 50% of all cases), obstructing most of blood supply to left ventricle; termed ‘widowmaker’ and frequently requires surgical bypass Myocardial ischemia (angina pectoris) Myocardial infarction  Right vs. Left Coronary ‘Dominance’ RCA LCA Posterior IV septum, via posterior Posterior IV septum , via posterior interventricular artery, supplied by interventricular artery, supplied by RCA in Right Dominant Heart LCA in Left Dominant Heart (~70% of patients) (infrequent) Third scenario: roughly equal contribution from LCA, RCA (co-dominance; infrequent)  Venous Drainage of the Heart A) Coronary sinus: main vein of heart → ends in RT atrium. B) Anterior cardiac veins: from the anterior wall of RT ventricle → end in RT atrium. C) Smallest cardiac veins (venae cordis minimi): very small veins from myocardium → end directly in its chamber of the heart.  Cardiac Veins Coronary Sinus LT atrium 3 3 2 1 A) Coronary sinus (posterior aspect, in coronary sulcus or posterior atrioventricular groove) drains blood from the heart tissue to the right atrium (like the SVC and the IVC). Tributaries include: 1. Great Cardiac Vein: travels with anterior interventricular a. (LAD) 2. Middle Cardiac Vein: travels with posterior interventricular a. (PDA) Identify the grooves of the heart and mention what passes through each Innervation of the Heart (Schema/Conceptual) IML Sympathetic Supply (Fight or Flight): Fibers originate in Intermedolateral cell column (IML) of spinal cord at T1-T5 levelleave laterally and synapse at sympathetic trunk  cardiopulmonary splanchnic nerves then descend to cardiac plexus to supply heart Sympathetic Clinical Note: Cardiac pain Trunk fibers travel retrograde w/ sympathetic supply; pain sensed at T1-T5 level (left shoulder) Parasympathetic Supply (Rest and Digest): Vagus Nerves (CN X) descend from brain to enter Cardiopulm. cardiac plexus; Splanchnic Reflex sensory fibers travel N. retrograde w/Vagus Nerves Cardiac ischemia can cause pain that is perceived as left chest wall/left upper limb pain (referred pain associated with T1-T5 dermatome; this corresponds to level of heart’s sympathetic supply) Because pericardium may be irritated, cardiac ischemia often also causes pain that is perceived as left shoulder and neck pain (referred pain associated with C3-C5 dermatome; this corresponds to level of the roots of the phrenic nerve)  Parasympathetic: Vagus Nerves (CN X) descend to feed into cardiac plexus Cardiac Plexus Sympathetic: Nerves that originate in T1-T5 level of spinal cord; synapse at sympathetic trunk (‘beads on a string’); cardiopulmonary splanchnic nerves then travel to cardiac plexus  Conducting System of the Heart (Conceptual) SA Node (located at junction of SVC and right atrium, near sulcus SA Node terminalis) initiates signal AV Node Signal is transmitted myogenically to AV node (located in interatrial septum near opening of coronary sinus) Signal then is transmitted to ventricles via AV bundle in ventricular walls regulating contraction of ventricles/papillary muscles AV bundle Ant. Pap. M. Some fibers pass through moderator band to anterior papillary muscle; helps coordinate contractions of this papillary muscle in synch with Moderator Band ventricle contraction  Clinical Correlations 1. Myocardial ischemia (angina pectoris). 2. Myocardial infarction. 3. ASD & VSD 4. Valve lesions. 5. Congenital anomalies.