Cardiology

Question 1

What is an ECG

Answer 1

a representation of the electrical events of the cardiac cycle

Question 2

what can ECGs identify

Answer 2

arrhythmias, myocardial ischaemia and infarction, pericarditis, chamber hypertrophy, electrolyte disturbances, drug toxicity

Question 3

What is the SA node?

Answer 3

dominant pacemaker with an intrinsic rate of 60-100 bpm

Question 4

what is the AV node?

Answer 4

back up pacemaker with intrinsic rate of 40-60 bpm

Question 5

what is the impulse conduction pathway?

Answer 5

SA node -> AV node -> bundle of His -> bundle branches -> purkinje fibres

Question 6

what does the p wave represent

Answer 6

atrial depolarisation

Question 7

what does the PR interval represent

Answer 7

time taken for the atria to depolarise and electrical activity to get through AV node

Question 8

what does the QRS complex represent?

Answer 8

ventricular depolarisation

Question 9

what does the ST segment represent?

Answer 9

interval between ventricular depolarisation and repolarisation

Question 10

what does the T wave represent

Answer 10

ventricular repolarisation

Question 11

what is dextrocardia

Answer 11

heart on the right side of the chest instead of left

Question 12

what ECG findings suggest acute anterolateral myocardial infarction?

Answer 12

ST segment elevation in anterior (V3 and V4) and lateral (V5 and V6) leads

Question 13

what does raised ST segments in inferior (II, III, aVF) leads suggest?

Answer 13

acute inferior MI

Question 14

where can you hear the apex beat?

Answer 14

5th intercostal space and mid-clavicular line, left ventricle

Question 15

what is the stroke volume?

Answer 15

the volume of blood ejected from each ventricle during systole

Question 16

what is cardiac output?

Answer 16

the volume of blood each ventricle pumps as a function of time

Question 17

what is the equation for cardiac output?

Answer 17

cardiac output = stroke volume x heart rate

Question 18

what is total peripheral resistance?

Answer 18

the total resistance to flow in systemic blood vessels from the aorta to vena cava

Question 19

what type of blood vessel has the highest resistance

Answer 19

arterioles

Question 20

what is the preload?

Answer 20

the volume of blood in the left ventricle before left ventricular contraction. how much blood is in the ventricle before it pumps

Question 21

what id end diastolic volume?

Answer 21

how much blood is in the ventricles before it pumps

Question 22

what is the afterload?

Answer 22

the pressure the left ventricle must overcome to eject blood during contraction

Question 23

what is starlings law?

Answer 23

force of contraction is proportional to the end diastolic length of cardiac muscle fibre - the more the ventricle fills, the harder it contracts

Question 24

What is heart sound 1

Answer 24

mitral and tricuspid valve closing

Question 25

what is heart sound 2?

Answer 25

aortic and pulmonary valv closure

Question 26

what is heart sound 3?

Answer 26

early diastole during rapid ventricular filling - normal for kids and preggers women, sign of mitral regurgitation and heart failure in adults/non preggers

Question 27

what is heart sound 4?

Answer 27

gallop in late diastole produced by blood being forced into a stiff hypertrophic ventricle - associated with LV hypertrophy

Question 28

what are the risk factors for athereosclerosis

Answer 28

Age, tobacco smoking, Fhx, high serum cholesterol, hypertension, obesity, diabetes

Question 29

what does an atherosclerotic plaque consist of?

Answer 29

lipid, necrotic core, fibrous cap and connective tissue

Question 30

How does aspirin work?

Answer 30

aspirin has an anti-platelet effect in coronary arteries and is a COX inhibitor which reduces prostoglandin synthesis including thromboxane A2 resulting in reduced platelet aggregation

Question 31

How do statins work?

Answer 31

HMG-CoA reductase inhibitors - reduces cholesterol production in liver - anti-atherosclerotic

Question 32

How do beta blockers work?

Answer 32

reduce heart rate, LV contractility and cardiac output of the heart by acting on B1 receptors in the heart as part of the adrenergic sympathetic pathway. (B1 activation -> Gs -> cAMP to ATP -> contraction) e.g bisoprolol and atenolol

Question 33

How does GTN spray work?

Answer 33

Nitrate is a venodilator - relaxes blood vessels by increasing activated cGMP which decreases calcium action by inhibiting calcium channels. this reduces preload and reduces the work of the heart and o2 demand

Question 34

how do Ca2+ channel antagonists work?

Answer 34

ARTEROdilator, dilates systemic arteries resulting in BP drop, reduces afterload on the heart, therefore less energy is required to produce the same cardiac output

Question 35

how does percutaneuos coronary intervention work?

Answer 35

Dilating atheromatous obstructions by inserting balloon and stent, inflating balloon and removing it, leaving just stent. makes artery bigger.

pros: less invasive, short recovery and repeatable
cons: risk of stent thrombosis, not good for complex disease

Question 36

how does a coronary artery bypass graft work?

Answer 36

left internal mammary artery is used to bypass proximal stenosis in LAD coronary artery

pros: good prognosis, deals with complex diseases
cons: invasive, risk of stroke or bleeding, one time treatment, long recovery

Question 37

what conditions are included in acute coronary syndromes?

Answer 37

ST- elevation myocardial infarction, unstable angina, non-ST-elevation myocardial infarction

Question 38

what is the difference between an unstable angina and a NSTEMI?

Answer 38

in a NTSEMI there is an occluding thrombus which leads to myocardial necrosis and a rise in troponin or creatine kinase-MB

Question 39

What is type 1 MI?

Answer 39

Spontaneous MI with ischaemia due to a primary coronary event e.g plaque