Applied Anatomy of the Heart Flashcards
what are the borders of the heart
- Upper right 3rd costal cartilage
- Upper left 2nd costal cartilage
- Lower right 6th costal cartilage
- Lower left 5th intercostal space, midclavicular line
what is the cardiac plexus made out of
- vagus nerve - decreases the heart rate
- sympathetic nerves - increases the heart rate
- general visceral afferent nerves
describe the pathway of the vagus nerve
CNX comes from the medulla runs down into the neck into the thorax and then into the cardiac plexus, gives off small branches which feed into the SAN
describe the pathway of the sympathetic nerves
from T1-T5 spinal cord levels, go to the sympathetic chain in then into the sympatheic chain ganglia then into the cardiac plexus, acts on the SAN to increase the rate of firing
where does sympathetic fibres enter the spinal cord between
T1-T5
where do the general visceral afferents enter the spinal cord and why is this important
T1 and T5 levels
- At these levels somatic afferents also enter the spinal cord
- Here they synapse with an interneuron and travel in the spinal cord to reach the brain
- The brain is unable to distinguish between visceral and somatic sensation and so pain is experienced within the somatic region
what is the right coronary artery divided in to
- Right coronary arteries – divides into the PDA and marginal branch
what is the left coronary artery divided in to
- Left coronary arteries – divides into the circumflex, left marginal branch of circumflex and LAD
what is the difference in appearance of the right and left coronary artery in an angiograph
RCA always looks C shape as it loops around the heart whereas LCA does not
LCA has three branches which you can see on the angiograph, it looks M shaped, easier to look at the LCA as all the arteries are going towards the apex of the heart
describe the blood supply to the conduction system
- RCA supplies the SA node
- The RCA supplies the AV node
- The interventricular descending arteries supply the bundle branches
what is the difference between right and left side dominance
- Right dominant heart – gives of PDA
- Left dominant – circumflex gives of PDA (only 30% of population)
what happens when there is bundle branch block
- Impulse travels through mycotyes – slows the impulse speed
- Prolongs QRS
- Loss of ventricular synchrony
where are the most common places that cause a myocardial infraction
- LAD
- RCA
- Circumflex
how do you do a coronary artery bypass
- take the great saphenous vein from the leg
- can sometimes use the internal thoracic mammary artery instead
what does an ECG do
- records the electrical activity to the heart
what types of leads are there and what plane do they look in in the heart
- 6 perocordial leads (chest) – horizontal plane
- 6 limb electrodes – vertical plane
name what part of the heart each lead looks at
AVL – left side of the heart AVR – right side of the heart AVF – inferior aspect of the heart Lead I – left side of the heart Lead II- inferior asepct Lead III – inferior aspect V1-V4- view of anterior V5-V6 – lateral/left side
name the position of the heart valves
- Aortic – Right 2nd intercostal space sternal edge
- Pulmonary – left 2nd intercostal space sternal edge
- Tricuspid – Left 6th intercostal space sternal edge
- Mitral – 5th intercostal space midclavicular line
what valves close in S1
mitral and tricuspid valves close- systole
what valves close in S2
aortic and pulmonary valves close– diastole
what is it called if a valve does not open properly
stenosis
what is it called if a valve does not close properly
regurgitation
what are some of the causes of valvular dysfunction
- ageing
- rheumatic fever
- bacterial endocarditis
what are the systolic murmurs
- mitral regurgitation
- aortic stenosis
what are the diastolic murmurs
- mitral stenosis
- aortic regurgitation
describe mitral regurgitation
- Mitral valve is not closing properly so the blood passes back through the valve
- Systole hear the heart murmur
- Pansystolic often louder in late systole
- Heard at apex
- Most common form of valvular heart disease
describe aortic stenosis
- Turbulence as blood has to be pushed through stenotic aortic valve
- Systolic (typically mid-systolic)
- Less severe – early systole, more severe – late systole because time taken to generate pressure to pass through stenotic valve
- Heard at right second intercostal space
describe mitral stenosis
- Rarely produces a soft rumbling diastolic murmur
- Mainly rheumatic in origin
describe aortic regurgitation
- Aortic valve is not closing properly so all the blood coming back through aorta into the left ventricle
- Rheumatic
- Sometimes associated with aortic stenosis
- Sound can be complex and often absent
- Decreased cardiac output due to regurgitation
- Elevates pre-load and afterload
- LVH – typically very dilated
what are the two types of cardiac remodelling
- Physiological – athletes or pregnancy
- Pathological – valvular disease and atrial fibrillation
define preload
- Volume of blood in ventricles at the end of diastole
define after load
- Resistance ventricle must overcome to circulate blood
what is preload increased by
- Increase the preload by increasing the blood volume as a whole – hypervolemia, valve regurgitation, heart failure(not all blood pumped out of the heart)
- Increased preload too much volume so the ventricle increases the volume of the ventricle and thins the walls
what is after load increased by
- Increased in – hypertension, vasoconstriction, valve stenosis, outflow stenosis
- Increased afterload makes it work harder so the heart gets thicker muscular walls and increases muscular mass
what are the two types of ventricular hypertrophy
concentric hypertrophy
eccentric hypertrophy
describe what concentric hyperstophy is caused by
- Due to Increased afterload – may be due to aortic stenosis or chronic hypertension
- Increasing the stiffness of the wall and reduce the lumen of the ventricle as well thus compromise ventricular filling this causes it to lead to eccentric hypertrophy as you get volume overload
- Can lead to eccentric hypertrophy
- Reduced compliance leads to volume overload
describe what eccentric hypertrophy can be caused by
- Volume overload/preload
Chamber dilatation
o Aortic and mitral regurgitation
o Systolic dysfunction (loss of cardiac inotrophy)
o Volume overload (hypervolaemia due to ventricular or renal failure)
o Others eg alcohol cocaine
- Elevates oxygen demand
- Lowers mechanical efficacy
(Laplace’s law)
the larger the atrium the..
the higher the risk of Atrial Fibrillation (AF)
describe the signs of atrial fibrillation
- Diagnosed ECG - absence P waves
- Reduced cardiac output
- Thrombi and syncope
