Cardiology Flashcards
Where is the heart located?
Inside the chest, Behind the sternum. pokes out slightly from behind the sternum. Most of it is slightly left of the midline and lies more anterior(front) than posterior (back).
What is the orientation of the heart?
Heart sits on the cardiac axis.
Right ventricle - predominately anterior structure
Right atrium- Pokes out from behind the sternum to the right of midline.
Left ventricle- pokes out from behind the sternum to the left of the midline,
Left atrium - posterior structure.
What are the great vessels of the heart?
Superior and inferior Vena Cava.
Main pulmonary artery
Pulmonary veins
Aorta
What is the function of the different great vessels?
Superior and inferior vena cava deliver venus blood to the heart.
Main pulmonary artery/pulmonary trunk - Take deoxygenated blood from heart to lungs.
Pulmonary veins- Deliver oxygenated blood from lungs back to heart.
Aorta - Provides blood to systemic circulation.
Name the valves of the heart?
Triscuspid valve - 3 leaflets - Separates the right atrium from the right ventricle.
Pulmonary valve - 3 leaflets - separates right ventricle from pulmonary artery.
Biscuspid valve / mitral (2 leaflets) - separates the left atrium from the left ventricle.
Aortic valve- 3 leaflets - separates the left ventricle and the Aorta. Oxygenated blood has to go through this valve before it leaves for systemic circulation.
what is the function of a valve?
Ensures that blood flows one way around the heart.
What side of the heart is involved in which circulation?
Right side of the heart drives pulmonary circulation.
Left side of the heart drives systemic circulation.
Describe the flow of blood through the heart?
Deoxygenated blood from the head and neck and arm vessels returns to left atrium through superior vena cava, blood from below diaphragm returns to RA through IVC.
blood passes through Tricupsid valve into RV.
RV contracts after filling, blood passes through pulmonary valve into main pulmonary artery/ pulmonary trunk to the lungs. Main PA divides into the left and right PA, which provide blood to the corresponding lung.
(left and right PA each divide into 2 lobar branches each and then into segmental branches.
Oxygenated blood returns from lungs to the LA through 4 pulmonary veins - 2 superior left and right, 2 inferior left and right.
Blood passes through Mitral valve/ bicuspid to the LV .
Left ventricle contracts and blood passes from LV through Aortic valve into descending Aorta which supplies blood to systemic circulation (body).
What are the different parts of the Aorta ?
Ascending Aorta - Aorta ascends from LV then becomes Aortic arch
Aortic Arch - arches superiorly, posteriorly then inferiorly ( Ends at t4 verterbrae).
Descending Aorta/ thoracic aorta - Spans from t4 to t12.
Abdominal Aorta - begins at T12 (ends at L4 vertebrae where it bi-furcates into right and left iliac arteries that supply lower body.
What anatomical variations can you have in the pulmonary veins?
Conjoined vein on the left (2 in 1 ) so 3 in total instead of 4 or having an accessory vein on the right, so 5 in total.
Name and describe the additional structure on the left atrium ?
Left atrial appendage/ left auricle (latin - ear) - ear shaped. Acts as an overflow (increases capacity of the left atrium)
What happen in low blood flow conditions in terms of left auricle?
Can lead to thrombosis - as there is a risk of stagnant blood which will result in clotting. Clot forms in the auricle, auricle breaks of atrium and follows the course of the blood into the left ventricle. Can cause stroke.
Describe thickness of chamber walls?
Atria have thin walls, left ventricle has thicker walls than right ventricle. Left ventricle has a thicker wall as it needs to drive systemic circulation.
Why do ventricle change the thickness of their walls?
Hypertension - high blod pressure - LV walls thicken as heart has to work harder to get blood out of the heart.
Aortic Stonosis - narrowing of aortic valve. Ventricle wall thickens to drive blood through the narrowing.
Solve hypertension/ aortic stonsis - ventricle wall thickness will decrease.
sometimes thickness can decrease abnormally - relating to chamber becoming dilated at the same time. Aortic regurgataions can cause this - blood flows back through aortic valve into LV causing it dilate during diastole.
Name and describe the components of the heart wall?
Epicardium (Epicardial fat) - Thin outer layer of the heart wall. Composed of thin layer of elastic connective tissue and fat. Located beneath/ inside pericardium. Layer contains coronary arteries.
Myocardium - Middle layer of the heart wall and the thickest layer - muscle tissue of the heart. composed of cardiomyocytes (specialised muscle cells).
Endocardium - Inner layer of the heart wall. composed of endothelial cells. smooth, elastic and non adherent surface for pumping and blood collection. Acts as barrier btw blood and heart muscle.
What is the pericardium?
A serous ( lubricated by fluid derived from serum) membrane that surrounds the heart. (3 layers)
Fibrous pericardium - Outer layer- tough fibrous part , stuck to the parietal layer of the serous pericardium.(anchors heart to surrounding walls) prevents heart from over- distending with blood.
Serous Pericardium (SP) - Inner layer - composed of 2 layers - parietal and visceral (epicardium). Slippy layer that lubricates heart and prevents friction during heart activity.
Pericardial cavity- Space between parietal and visceral layer of SP.
How many leaflets do the valves have?
Tricuspid - 3
mitral / bicuspid - 2
pulmonary and Aortic - 3
Tricuspid and mitral link to sub- valvular structures - cordae tendinae which attach to papillary muscles that attach to ventricle walls preventing prolapse(valve becomes to floppy so does not close tightly enough)
Describe some types of Myocardial dysfunction?
Systolic heart failure- failure of heart to contract adequately
Diastolic heart failure - failure of the wall to relax adequately.
How can you measure cardiac function ?
Echocardiography - ultrasound of the heart
metric commonly used :
END DIASTOLIC VOLUME (EDV) - volume of blood in the ventricles at the end of diastole when LV is most full.
END SYSTOLIC VOLUME(ESV) - volume of blood in the LV that remains after it contracts at the end of systole.
STROKE VOLUME - Volume of blood ejected in one cardiac cycle = EDV-ESV.
EJECTILE FRACTION (EF) - volume of blood ejected in one cardiac cycle as a percentage of the EDV.
What can affect heart function?
Ischaemia - Blood flow to through one or more of the coronary arteries is reduced. Myocardium does not get enough blood/ oxygen and does not contract very well.
Valve disease - severe aortic stenosis - LV wall thickness increase to provide more pressure to pass through narrowing. Does not do this very efficiently - constant strain)
Aortic regurgitation- heart overloaded with blood - contraction not efficient.
extrinsic compression - pericardium or (Tamponade - fluid in the pericardial cavity squashes heart limiting venus return to heart- lack of efficient pumping. Patients with tamponade become unwell very quickly.
Disorders of heart rhythm.
What is cardiomyopathy ?
Disease of heart muscle - make sit harder for heart to pump blood to the rest of the body- may lead to heart failure.
What are the divisions of a embryological heart?
Endocardial cushions - Separate atria from ventricles.
Septum premum- membrane grows down towards the endocardial cushion- separates the left and right atria. This leaves a small hole at the bottom - ostium premum. This closes up and the ostium secundum hole forms(second hole)with the septum premum.
Septum secundum grows alongside the septum premum forming the foreman ovale - flap valve.
There is a 2nd septation (division between the ventricles) - Interventricular septum - consists of membranous and muscular layer. help chamber contract and empty blood.
Importance of Foreman Ovale ?
Important in fetal circulation because fetus does not need its lungs. Foreman ovale allows the lungs (which are at higher pressure) to be bypassed. Blood goes straight from RA to LA.
What happens at birth affecting the foreman Ovale?
At birth, lungs fill with air - drop in pressure in the pulmonary circulation - LA drops in pressure so foreman ovale closes. Blood stops bypassing he lungs.
Interventricular septum also closes ( consists of membranous and muscular layer)
