Cardiology

Question 1

What is a normal sinus rhythm characterised by?

Answer 1

PR interval: 0.12-0.2 seconds
QRS complex: 0.08-0.12 seconds
QT interval: 0.36-0.44 seconds

Question 2

What is Mobitz type I (Wenckebach) heart block?

Answer 2

type of second degree heart block

characterised by dropped P wave WITH PR-interval prolongation

Question 3

What is Mobitz type II heart block?

Answer 3

type of second degree heart block

characterised by dropped P wave WITHOUT PR-interval prolongation

Question 4

What is 3rd degree heart block?

Answer 4

complete AV dissociation

Question 5

What is 1st degree hearth block?

Answer 5

PR interval > 0.2s

with no P waves missed

Question 6

Which part of the ECG represents atrial depolarisation?

Answer 6

P waves

Question 7

What is a common cardiac defect in children with Down’s syndrome? How does it clinically present?

Answer 7

Eisenmenger syndrome 
(due to underlying VSD)
Presents with:
- clubbing
- cyanosis
- tiring easily

Question 8

What is Dressler’s syndrome? When does it often occur?

Answer 8

autoimmune mediated pericarditis

occurs often 2-6 wells after an MI

Question 9

How are the aorta and pulmonary trunk formed? What pathology can form when this malfunctions? What are the presenting Sx?

Answer 9

trunks arteriosus divided into the aorta and pulmonary trunk
process mediated by neural crest cell migration
Can lead to Tetralogy of Fallot if fails
Sx: SoB, boot-shaped heart on CXR, cyanosis on distress

Question 10

What are the main features of Tetralogy of Fallot?

Answer 10

VSD
right ventricular hypertrophy
overriding aorta
pulmonary artery stenosis

Question 11

What is the function of Troponin I?

Answer 11

binds actin

stabilises the troponin-tropomyosin complex in place

Question 12

What is T wave inversion indicative of in an ECG?

Answer 12

• ischaemic heart disease

Question 13

What does troponin C bind to?

Answer 13

Calcium ions

Question 14

What are the 3 subunits of troponin?

Answer 14

• Trop C
• Trop T
• Trop I

Question 15

What does troponin T do?

Answer 15

binds tropomyosin

forms the troponin-tropomyosin complex

Question 16

What is troponin?

Answer 16

complex of 3 trop subunits

involved in skeletal and cardiac muscle contraction

Question 17

What ion movement causes rapid depolarisation in the cardiac action potential?

Answer 17

Rapid sodium influx (funny current)

Question 18

Which ion influx is responsible for the plateau phase of a cardiac AP?

Answer 18

calcium influx

phase 2 = plateau period

Question 19

What occurs in phase 4 of the cardiac AP?

Answer 19

potassium influx

maintains the electrochemical gradient

Question 20

In which phase of the cardiac AP, does potassium efflux occur?

Answer 20

phase 1 and phase 3

Question 21

When does sodium efflux occur in the cardiac AP?

Answer 21

phase 4

due to Na+/K+ ATPase pump

Question 22

What are the 4 phases of cardiac AP?

Answer 22

Phase 0
Rapid depolarisation

Phase 1
Early repolarisation

Phase 2
Plateau

Phase 3
Final repolarisation

Phase 4
Restoration of ionic concentrations

Question 23

What occurs in the phase 0 of the cardiac AP?

Answer 23

= rapid depolarisation

• rapid Na+ influx
• then deactivation of channels

Question 24

What happens in phase 1 of the cardiac AP?

Answer 24

= early repolarisation

• Potassium efflux

Question 25

What happens in phase 2 of the cardiac AP?

Answer 25

= plateau slow Ca2+ influx

Question 26

What happens in phase 3 of the cardiac AP?

Answer 26

= final repolarisation potassium efflux

Question 27

What happens in phase 4 of the cardiac AP?

Answer 27

= restoration of ionic concentrations - resting potential is restored by Na+/K+ ATPase slow entry of Na+ into cell (by funny current) reduced potential difference, allowing next AP to be stimulated

Question 28

Which coronary artery supplies the SA node? Where does it originate from?

Answer 28

sinoatrial node artery | origin: in 60% of people it is a branch of the RCA, the remainder of people it comes from the left circumflex artery