Cardiovascular

Question 0

What causes the plateau in the AP of the myocardium?

Answer 0

Calcium channels open in response to the depolarisation slower than the Na+ channels prolonging the depolarisation–> plateau

Question 1

What is the resting potential of the myocardium?

Answer 1

-90mV

Question 2

What is the mechanism for the cardiac AP?

Answer 2

Na+ channels open 1st from depolarisation = Na+ influx –> rapid depolarisation
Ca2+ channels then open in response to the depolarisation but slower than the Na+ channels –> plateau
K+ channel conductance decreases following depolarisation allowing the Ca2+ to maintain the depolarisation.
After 200ms K+ conductance increases = replarisation

Question 3

Where is the sinus rhythm generated?

Answer 3

Pacemaker cells –> Sino atrial node

Question 4

What stops the AP being transmitted from the atria to the ventricles?

Answer 4

Fibrous rings (anulus fibrosus cordis) direct the AP to the AV node

Question 5

What does the P-wave on an ECG show?

Answer 5

depolarisation across the atria

Question 6

What does the QRS complex show on an ECG?

Answer 6

Spread of the depolarisation across the ventricles

Question 7

What does the T- waves on an ECG show?

Answer 7

Repolarisation of the ventricles

Question 8

Why is the T- wave a positive inflection on an ECG?

Answer 8

It is a -ve -ve, which shows up as positive.

I.e. The polarisation is moving away from the ecg node.

Question 9

How is HR calculated on an ECG?

Answer 9

Distance between R waves:

300 / No. Large squares in the R-R interval

Question 10

What do bifid p-waves indicate?

Answer 10

Mitral stenosis

Question 11

What will right axis deviation show up as on an ECG?

Answer 11

The average direction move clockwise –> Lead 1 becomes predominantly -ve.

Question 12

What does left axis deviation show up as on an ECG?

Answer 12

leads 2 and 3 become predominantly -ve.

Question 13

What do tall, tented t-waves on an ECG indicate?

Answer 13

Hyperkalaemia

Question 14

How does right bundle branch block appear on an ECG?

Answer 14

MaRroW- QRS has M and W shapes

Question 15

How does left bundle branch block show up on an ECG?

Answer 15

WilliaM- QRS has W and M shapes

Question 16

What is 1st degree heart block and how does it appear on an ECG?

Answer 16

A delay at the AVN/ bundle of his.

PR interval is >0.2s

Question 17

What is 2nd degree- Mobitz type 1 heart block?

Answer 17

Progressively longer PR interval until there’s a ‘dropped beat’.
Described as Wenkebach P:QRS

Question 18

What is 2nd degree mobitz type 2 heart block?

Answer 18

Normal PR interval with QRS dropped at random.

Due to a block at the bundle of His

Question 19

What is 3rd degree heart block?

Answer 19

Complete dissociation between the atria and the ventricles.

Question 20

What is syncope?

Answer 20

Transient loss of consciousness due to global cerebral hypoperfusion.

Question 21

What are the types of syncope?

Answer 21

Reflex, orthostatic hypotension, cardiac syncope

Question 22

What is acute coronary syndrome?

Answer 22

A range of disorders such as MI, unstable angina

All caused by the underlying problem of sudden decrease in blood flow to part of the myocardium.

Question 23

What is the initial management of ACS?

Answer 23

MONA:- 
Morphine
Oxygen
Nitrates
Aspirin

Question 24

What drugs are used in the secondary prevention of ACS?

Answer 24

MI-5:-
Aspirin
Clopidogrel
ACE inhibitor
B-blocker
Statin