Heart Anatomy.pdf

Heart Anatomy Vet-Prep Brady Little, DVM, MSc - Objectives: The following topics will be covered (be able to analyze, describe, and apply these topics): Position / orientation of the heart within the canine thorax Surface features of the heart Internal features of the heart Normal blood flow (pulmon...

Heart Anatomy Vet-Prep Brady Little, DVM, MSc - Objectives: The following topics will be covered (be able to analyze, describe, and apply these topics): Position / orientation of the heart within the canine thorax Surface features of the heart Internal features of the heart Normal blood flow (pulmonary and systemic circulation) as well as blood supply the heart muscle itself Sounds of Cardiac auscultation Base: oriented dorsocranially Apex: points ventrocaudally and to the left Left view of the heart AKA Auricular surface (both auricles are prominently observed from this view) 1, Left auricle; 2, pulmonary trunk; 3, right ventricle; 4, left ventricle; 5, Right auricle 5 Right view of the heart AKA Atrial surface (the right atrium is the prominent structure observed from this view) 1, Right atrium; 2, caudal vena cava; 3, aorta; 4, cranial vena cava Surface Topography Coronary groove Separation of the atria and ventricles Contains the coronary vessels Often contains fat Encircles the base of the heart Interventricular grooves Separation of the ventricles 1. 2. Paraconal interventricular groove Subsinuosal interventricular groove RV Parietal (Marginal) Wall LV Parietal (Marginal) Wall 1, Right atrioventricular valve 2, left atrioventricular valve 3, aortic valve 4, pulmonary valve Interior Features 4 AV valve cusps… (valve leaflets) Marginal AKA parietal cusps - originate from the outer ventricular wall Septal cusp originates from the interventricular septal wall Cusps are anchored to the inner walls of the ventricles by fibrous “strings” called chordae tendineae 6 Papillary muscles secure the chordae tendineae to the inner walls of the ventricles. AV valves close during systole to prevent backflow of blood into the atria Interior of the RIGHT side of the heart 1, Cusp of right atrioventricular valve 2, chordae tendineae 3, papillary muscles 4, pulmonary valve 5, right auricle. 6, right ventricle TWO completely separate circuits! pulmonary circulation systemic circulation Gas exchange in the lungs occurs via the pulmonary circuit Gas exchange to all other body cells occurs via the systemic circuit The right side of the heart receives deoxygenated blood from systemic circulation and sends blood into pulmonary circulation The left side of the heart receives oxygenated blood from pulmonary circulation and sends blood into systemic circulation Schematic drawing: 1, Left ventricle; 2, aorta; 3, capillary bed of head, neck, and forelimb; 4, abdominal aorta; 5, liver; 6, capillary bed of intestines; 7, portal vein; 8, capillary bed of kidneys; 9, capillary bed of caudal part of the body; 10, caudal vena cava; 11, cranial vena cava; 12, right ventricle; 13, pulmonary trunk; 14, capillary bed of lungs; 15, pulmonary vein; 16, hepatic veins. - The right atrium receives blood from the cranial and caudal vena cava (and from venous return from heart muscle itself) - Right Atrium pumps blood into the Right Ventricle through the Right AV (Atrioventricular) Valve - (“Tricuspid”.. Sometimes this name is a misnomer) (The RIGHT AV valve stops backflow of blood from the Right ventricle into the Right atrium during systole) - Right Ventricle contracts to send blood to the lungs through the Pulmonary trunk & pulmonary arteries The pulmonary semilunar valve prevents backflow of blood from pulmonary trunk into the right ventricle during diastole - OXYGENATION IN THE LUNGS - Oxygenated blood travels back to the heart through the pulmonary veins into the Left Atrium - Left Atrium pumps blood into the Left Ventricle through the Left AV Valve (“Mitral”) (The LEFT AV valve stops backflow of blood from the Left ventricle to the Left atrium during systole) - Left Ventricle contracts to send blood through the Aortic semilunar valve and into the Aorta out to the rest of the body (and to supply the heart muscle itself) The Aortic semilunar valve prevents backflow of blood from aorta into the Left ventricle during diastole Pulmonary semilunar valve - located between right ventricle and the pulmonary Arteries (trunk) Aortic semilunar valve - located between the left ventricle and the aorta Left AV Valve - located between left atria and Left ventricle Right AV Valve - located between right atria and right ventricle Systole = heart contraction Diastole = heart rest The first tissue supplied by the heart is the heart itself! heart auscultation P M I Listening for the oints of aximum ntensity (PMI): Associated with each valve Left Side: “P” = pulmonary valve sound (3rd IC space) “A” = aortic valve sound (4th IC space) “M” = “mitral”/left AV sound (5th IC space) Right Side: “T” = “Tricuspid”/Right AV sound (4th IC space) 2 NORMAL sounds of the heart are caused by blood stopping at valves Closure of Left and Right Atrioventricular Valves Closure of Aortic and Pulmonic semilunar Valves S1 S2 Blood Flow from one structure to another (through valves) is normally SILENT * In normal dogs and cats