applied anatomy of the heart Flashcards
what are the borders of the heart?
- Upper right: 3rd costal cartilage
- Upper left: left 2nd costal cartilage
- Lower right: 6th costal cartilage
- Lower left: 5th intercostal space midclavicular line
what is the cardiac plexus made up of?
vagus nerve
sympathetic nerves
general visceral afferent nerves
where does the vagus feed into the heart and what effect does it have on the heart?
feeds into the SAN
parasympathetic - slows down HR
where do sympathetic nerves from the heart enter the spinal cord?
T1-T5
what effect do sympathetic nerves have on the heart?
increase the rate of firing
where do general visceral afferents feed into?
spinal levels T1-T5
where is referred heart pain felt and why?
dermatomes T1-T5
brain can’t differentiate between GVA and somatic nerves bc they enter the spinal cord at the same spinal level
what are the branches of the right coronary artery?
posterior interventricular/descending artery
marginal branch
what are the branches of the left coronary artery?
circumflex branch
left marginal branch of circumflex artery
left anterior descending
what artery supplies the SAN?
right coronary artery
what artery supplies the AVN?
right coronary artery
what arteries supply the bundle branches?
interventricular (descending) arteries
what is a right dominant heart?
posterior descending artery is supplied by the RCA which supplies the myocardium of the inferior 1/3 of the interventricular septum
what is a left dominant heart?
PDA supplied by the LCA. All of the IV septum supplied by the LCA
what is the risk in a left dominant heart?
LCA blockage means both bundle branches have their blood supply cut off
what happens as a result of bundle branch block?
- bundle branch becomes ischaemic
- doesnt conduct impulses properly
- use altered pathways for depolarisation (cardiac myocytes conduct the impulses instead of using the bundle branches)
- slows impulse speed
- prolongs QRS
- loss of ventricular synchrony
what are the 3 most common places for stenosis of coronary arteries?
left anterior descending
right coronary artery
circumflex artery
how long does it take for severe ischaemia to register on an ECG?
minutes
how many electrodes and perspectives are there on an ECG?
10 electrodes
12 perspectives
how many chest leads are there and how many perspectives do they provide?
6 chest leads 6 perspectives (horizontal plane)
how many limb leads are there and how many perspectives do they provide?
4x limb leads
6x perspectives
what leads give a lateral view of the heart?
I, aVL, V5 and V6
what leads give an anterior view of the heart?
V3, V4
what leads give a septal view of the heart?
V1, V2
what leads give an inferior view of the heart?
II, III and aVF
what leads correspond with the right coronary artery?
main artery on the inferior surface
leads II, III, aVF
what leads correspond with the left anterior descending artery?
main artery on the anterior surface
V3, V4
what leads correspond with the circumflex?
main artery on the lateral surface
I, aVL, V5, V6
where are the heart valves located?
o Aortic – upper right 3rd costal cartilage
o Pulmonary – upper left 2nd costal cartilage
o Tricuspid – lower right 6th costal cartilage
o Mitral – lower left 5th intercostal space midclavicular line
where do you auscultate the heart valves?
o Aortic – right 2nd intercostal space
o Pulmonary – left 2nd intercostal space
o Tricuspid – 6th intercostal space
o Mitral – 5th intercostal space midclavicular line
what causes the characteristic lub dub noises of the heart?
o Lub (S1) when mitral valves and tricuspid close (systole) o Dub (S2) when aortic and pulmonary valves close (diastole)
what 2 things can go wrong with the heart valves?
stenosis
regurgitation
what is stenosis?
when the valves dont open properly
what is regurgitation?
when the valves dont close properly
what type of murmur is mitral regurgitation?
systolic murmur
what causes mitral regurgitation?
Mitral valve doesn’t close properly – can hear when blood passes back through valve into the atria
what does mitral regurgitation sound like?
pansystolic
often louder in late systole
where is mitral regurgitation heard?
heard at the apex
what is the most common form of valvular heart disease?
mitral regurgitation
what type of murmur is aortic stenosis?
systolic murmur
why do you hear turbulence in aortic stenosis?
as blood has to be pushed through stenotic aortic valve
describe the different severities of aortic stenosis throughout systole and why this occurs
less severe in early systole
more severe in late systole
bc time taken to generate pressure to pass through stenotic valves
where is aortic stenosis heard?
right second intercostal space
what does mitral stenosis sound like?
rarely produces a soft rumbling diastolic murmur
what does aortic regurgitation sound like?
complex and often absent
what are the further complications of aortic regurgitation?
decreased cardiac output bc of regurgitation
elevates preload and afterload
LVH - typically very dilated
what causes change in heart size
- changes based on workload
- workload can be physiological (athletes, pregnancy) or pathological (valvular disease, atrial fibrillation)
define preload
volume of blood in ventricles at the end of diastole
define afterload
resistance ventricle must overcome to circulate blood
what does preload increase in?
hypervolemia, valve regurgitation, heart failure
what does afterload increase in?
(chronic) hypertension, vasoconstriction, valve (aortic) stenosis, outflow stenosis
what is concentric hypertrophy?
hypertrophic growth of a hollow organ without overall enlargement – walls thicken, and capacity/volume are reduced
how does concentric hypertrophy occur?
increased afterload bc of aortic stenosis or chronic hypertension
increased resistance
wall thickness increases to overcome resistance - new sarcomeres
what are the disadvantages of wall thickness increasing?
compliance is reduced (stiff)
ventricular filling is compromised (diastolic dysfunction)
what is eccentric hypertrophy?
dilation of the left ventricular chamber (normal response to healthy exercise)
what causes eccentric hypertrophy?
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
what causes atrial enlargement?
in response to mitral or tricuspid valve pathology
what is atrial remodelling?
any persistent change in atrial structure
what is the link between atrium size and the risk of atrial fibrillation and why?
larger the atrium the higher the risk of AF bc you’re disrupting the electrical conduction pathways
how is atrial fibrillation diagnosed?
absent P waves on an ECG
reduced cardiac output
thrombi and syncope
how is left atrium enlargement seen on an x-ray?
seen as a double density over the right atrium
how is left ventricular enlargement seen on an x-ray?
heart looks like a boot
