Session 3 Flashcards
Locate the main venous tributaries draining the heart tissue and describe the inflow into the right chamber of the heart
Five tributaries - great cardiac vein, small cardiac vein, middle cardiac vein, left marginal vein, left posterior ventricular vein
Inflow is from superior and inferior venae cava, coronary sinus.
Identify and describe the distribution of the right and left coronary arteries
Right coronary artery - right atrium, SA and AV nodes, posterior part of IV septum
Right marginal - right ventricle, apex
Posterior interventricular - right ventricle, left ventricle
Left coronary artery - left atrium, left ventricle, IV septum
Left anterior descending - right ventricle, left ventricle
Left marginal - left ventricle
Circumflex - left atrium, left ventricle
Explain the differences in thickness of the walls of the ventricle of the heart
Left ventricle - thicker, more muscle as pumps blood out of the aorta around the entire body
Right ventricle - thinner as blood is only pumped to the lungs, a relatively short distance
Explain the structure and function of the valves of the heart and great vessels in relation to the blood flow through them
Atrioventricular valves (close during relaxation of atria and contraction of the ventricles):
Tricuspid (RA–>RV) has three cusps attached to the fibrous ring of the heart skeleton.
Mitral (LA–>LV) is closed by the contraction of papillary muscles attached to the valves by chordae tendinae.
Semilunar valves (close during relaxation of ventricles and elastic recoil of outflow vessels by back flow of blood):
Pulmonary (RV–>pulmonary artery) is closed by three cusps attached to a fibrous ring
Aortic (LV–> aorta) is closed by three cusps attached to a fibrous ring
Pulmonary arteries receive deoxygenated blood from the right ventricle and deliver it to the lungs.
Pulmonary veins receive oxygenated blood from the lungs and deliver it to the right atrium.
The aorta receives oxygenated blood from the lungs and delivers it to the body.
Superior vena cava receives deoxygenated blood from the upper body and delivers it to the right atrium.
Inferior vena cava receives deoxygenated blood from the lower body and delivers it to the right atrium.
Describe the circulation of blood in the heart
SVC/IVC –> right atrium –> right ventricle –> pulmonary artery –> lungs –> pulmonary veins –> left atrium –> left ventricle –> aorta –> body
Describe the frequency and types of congenital malformation of the heart and great vessels
Common (6-8/1000 births)
Most common:
Ventricular Septal Defects
Atrial Septal Defects.
Other defects include:
Transposition of the Great Vessels - septum that forms in truncus arteriosus does not spiral
Tetralogy of Fallot - outflow portion of IV septum is too far in anterior, cephalic direction
Describe the types of VSD
Abnormal opening in IV septum, most commonly in membranous portion. Since left ventricular pressure is higher than right, blood will flow from left to right. The amount of flow depends on the size of the lesion.
Describe the types of ASD
Opening in the septum between the two atria e.g. failure of foramen ovale to close - ostium secundum ASD. Ostium primum ASD is less common.
Left atrial pressure is greater than right so flow is from left to right - no mixing of deoxygenated blood with oxygenated blood being pumped around systemic circulation.
Explain the effects of a left to right shunt
No mixing of deoxygenated blood with oxygenated blood being pumped around systemic circulation = acyanotic lesion.
Explain the causes of congenital cyanosis heart defect
Tetralogy of Fallot (VSD, Overriding aorta, Pulmonary stenosis, Right ventricular hypertrophy) - right ventricle must operate at a higher pressure to pump blood through pulmonary artery.
Allows right to left shunting and mixing of deoxygenated blood with oxygenated blood going to the systemic circulation, resulting in cyanosis.
Tricuspid atresia - lack of development leaves no right ventricle inlet
Hypoplastic left heart - LV and ascending aorta fail to develop. Lethal without surgical intervention.
Describe the functional importance of Transposition of the Great Arteries
Transposition of the Great Arteries - two unconnected parallel circulations.
RV–>aorta, LV–>pulmonary trunk.
Not compatible with life after birth unless a shunt exists.
The ductus arteriosus can be maintained patent and/or ASD formed.
Explain the significance of a patent Ductus Arteriosus
Blood flow is from the aorta –> pulmonary artery.
A mechanical murmur is heard constantly, as pressure in the aorta is always greater than in the pulmonary artery.
Chronic left to right shunting can lead to vascular remodelling of the pulmonary circulation and an increase in pulmonary resistance.
If pulmonary circulation resistance increases greater than systemic circulation, the shunt will reverse direction (Eisenmenger Syndrome)
Describe the effects of Coarctation of the Aorta
Narrowing of the aortic lumen in the region of ligamentum arteriosum. This narrowing increases the afterload on the left ventricle and can lead to left ventricular hypertrophy.
Blood supply to upper body is unaffected but is reduced to lower body.
Detection in adults - weak and delayed femoral pulse, upper body hypertension
