Flashcards in CVS Deck (111)
When are the 1st and 2nd heart sounds heard?
-1st = Closure of AV valves (mitral and tricuspid) -2nd = Closure of outflow valves (aortic and pulmonary)
What causes the 3rd heart sound? What condition is it common in?
-Rapid ventricular filling causes oscillation of blood back and forth between the ventricles mid diastole-Heart failure
What causes the 4th heart sound? In what conditions is 4th heart sound NOT possible?
-Atrial contraction against a stiff ventricle-AF or atrial flutter (requires atrial contraction)
Name the main branches of the arch of aorta
-Brachiocephalic (right subclavian and right common carotid)-Left common carotid-Left subclavian
Describe the coronary arterial supply
-Coronary arteries branch off aorta and travel near auricles-Left coronary artery is very short and splits immediately into left circumflex and left anterior descending-Right coronary is longer and gives off right marginal and then travels around the back -Posterior interventricular artery arises from right coronary and LAD joins it and it travels in interventricular groove
What drains into right atrium?
-SVC/IVC-Coronary sinus-small tributary veins
State the borders of the heart on xray
-Left border =mainly LV-Right border = mainly RA-Diaphragmatic = LV and RV
Briefly describe the pericardium and its function.
-Fibrous sac consisting of 2 layers, an outer fibrous and inner serous (parietal and visceral) -Tough and non distensible which protects the heart and prevents over filling-Pericardial fluid between serous layers provided lubrication for friction free movement
What is pericardial effusion/cardiac tamponade and how does it present
-Abnormal collection of fluid within the pericardial cavity-Becomes tamponade when the heart becomes compromised by restriction of filling and pumping-Buldging neck veins, muffled heart sounds and low bp
State where the left and right laryngeal nerves loop
-Left = arch of aorta-Right = right subclavian
Name the layers of the artery wall. In which layer does atherosclerosis occur. describe the pathogenesis of atherosclerosis
-Tunica intima, tunica media and tunica adventitia-Tunica intima-Oxidised LDL infiltrates the tunica intima and is taken up by macrophages which are now known as foam cells and form a fatty streak on the vessel wall. Smooth muscle cells migrate from the media into the intima and fibroblasts deposit collagen and structural proteins. Smooth muscle lines up beneath the endothelium and forms a fibrous cap. this is now a simple plaque. More migration of cells and platelet infiltration and adherence to endothelium causes development of plaque and cholesterol cleft and calcifcation occur in the centre forming a complex plaque
Describe the spread of excitation through the heart
-Originates at SAN and spreads over surfaces of atria to AVN-AVN holds for 120ms before it passes down the septum and down L and R bundle of his then through the ventricular myocardium from in to out causing ventricle contraction from the apex upwards
Briefly describe the cardiac cycle from late systole
-Ventricles contracted and intraventricular pressure greater then arterial pressure so outflow valves open and blood expelled into arteries-Intraventricular pressure falls and backflow closes the outflow valves= isovolumetric relaxation-Pressure in ventricles falls below atrial pressure which have been filling with blood and are now contracting -> av valves open and ventricles begin to fill-Pressure in ventricles becomes greater then atria and backflow closes AV valves = isovolumetric contraction-Intraventricular pressure rises greater than arterial and cycle starts again
What is the cardiogenic field and how does this form the primitive heart tube?
-An undifferentiated area within an embryo from which the heart, vessels and blood cells arise from-Pair of endocardial tubes form and lateral folding results in fusion at the midline, forming the primitive heart tube
What is the effect of cephalocaudal folding on the heart tube?
-Relocates the primitive heart tube, within the pericardial cavity, to the correct anatomical location
Describe the primitive heart tube and state the fates of each bit
-sinus venosus= RA
-primitive atrium= RA and LA
-primitive ventricle= LV
-bulbus cordis= RV
-truncus arteriosus= Aorta and PT
-aortic roots= arterial branches
Why is looping a key developmental event?
-Ensures septation of chambers and outflow tract-Development of transverse sinus-Optimises space for growth
What is looping of the primitive heart tube?
-Continued elongation of the primitive heart tube results in the tube bending and folding upon itself-The primitive ventricle pushes ventrally, caudally and right-The primitive atrium pushes dorsally, cranially and left
What is the atrioventricular canal?
-A constriction between the primitive atrium and the primitive ventricle which allows communication between the atria and ventricles before septation occurs
When is the oblique sinus formed?
-During formation of the left atrium when the LA absorbs the pulmonary veins and expands
What happens to the sinus venosus during atrial development?
-As venous return shifts to the right side of the heart, the left horn of sinus venosus recedes and the right atrium absorbs the right sinus horn
What do the right and left atria develop from?
- Right =Most of the primitive atrium and the right sinus horn-Left = LA sprouts pulmonary vein and then proximal portions of these branches and expands to form complete LA
Name the shunts in the feotal system and state their functions in utero
-Ductus arteriosus -> allows blood from the PT into aorta to bbypass the lungs-Ductus venosus -> allows the blood to bypass the livr and pass from umbilical vein to IVC-Foramen ovale -> allows oxygenated blood to streamn across the right atrium into the left atrium
What are the aortic arches?
-A bilateral system of arched vessels, connected to the primitive heart, which undergo extensive remodelling to create the major arteries leaving the heart
What are the derivatives of the 4th and 6th aortic arch?
-4= Right -> right subclavian artery -Left -> arch of aorta-6= R-> Right pulmonary artery -L->Left pulmonary artery and ductus arteriosus
What is the function of the recurrent laryngeal nerve?
-Innervate the intrinsic muscles of the larynx
Briefly describe atrial septation
1)endocardial cushions form on dorsal/ventral av canal and fuse in the midline
2)Septum primum grows towards the endocardial cushions -> ostium primum before fusion
3)Ostium secundum appears by apoptosis in septum primum and fusion occurs with endocardial cushions
4)Septum secundum grows in a cresent shape and forms a functional shutter valve over ostium secundum. this is foramen ovale
Briefly describe ventricular septation
-Muscular septum grows upwards from midline of primitive ventricles towards endocardial island
-Stops before fusion
-Membranous septum grows down from conotruncal septum and fuses with muscular septum and endocardial island to close
Briefly describe outflow septation
-Pair of staggered endocardial cushions appear in truncus arteriosus
-Septum grows from staggered cushions and develops caudally to fuse with muscular ventricular septum
-Splits left and right heart with relevant outflow tracts