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Flashcards in ECG + risk stratification Deck (182)
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1

The action potential starts at the ... node and is ... at the ... node before entering the ... ... ...

SA Delayed AV Bundle of His

2

conduction through the Bundle of His and the Purkinje fibres is extremely ...

rapid

3

The ventricles depolarise from ...cardium to ...cardium

endocardium epicardium

4

True or false, the heart depolarises from base to apex?

False - it depolarises from apex to base

5

Which heart cells show intrinsic audtorhythmicity?

SAN AVN Purkinje fibres

6

Describe 2 features of auto-rhythmic cells in the heart

They pass their excitation and hence their contraction to each other

Intercalated discs connect adjacent cardiac muscle cells

7

What is the natural pacemaker of the heart? What rate does it beat at?

SAN 90-100bpm

8

A beat generated outside the normal pacemaker is an ... beat

ectopic

9

The ... pacemaker of the heart normally drives the heart and ... other pacemakers

fastest suppresses

10

The AVN pacemaker beats at ...-... bpm, and the Bundle of His "safety net" beats at ...-...

40-60 15-30

11

Depolarisations of auto-rhythmic cells rapidly spread to adjacent cells through ... ...

gap junctions

12

Why do myocardial contractile cells have a different looking action potential to myocardial auto-rhythmic cells?

Due to the presence of calcium channels

13

Intercalated discs in the amongst the heart cells allow.....

branching of the myocardium

14

4 structural features of cardiac cells

Intercalated discs Gap junctions Many mitochondria Large T tubules

15

Describe the process of cardiac contractile cell muscle excitation, contraction and relaxation (10)

1. AP enters from adjacent cell 2. VGCCs open, Ca2+ enters cell 3. Ca2+ induces Ca2+ release from ryanodine receptor channels 4. Local release causes Ca2+ spike 5. Summed Ca2+ sparks create a Ca2+ signal 6. Ca2+ binds to troponin to initiate contraction 7. Relaxation occurs when Ca2+ unbinds troponin 8. Ca2+ is pumped back into SR for storage 9. Ca2+ is exchanged with Na+ 10. Na+ gradient is maintained by Na+/K+ ATPase

16

ECGs ... each individual membrane potential from contractile cells

summate

17

Atria contract just ... p-wave is formed on the ECG recorder

after

18

PR segment represents...

conduction through AVN

19

T wave represents...

ventricular repolarisation

20

If wave of contraction moves toward positive electrode what deflection do you see on ECG? And what do you see if wave is moving away?

Towards - upward Away - downward

21

Waveform on ECG gives indication of where cardiac axis vector is moving relative to ...

electrode

22

Mean axis of polarity of heart exists as a ...

vector

23

3-lead ECG leads and colour: Red - Yellow - green - Black -

Red - right arm Yellow - left arm Green - left leg Black - right leg (earth lead)

24

Name the 3 unipolar leads

aVR, aVL, aVF

25

aVR normally has a ... deflection

downward

26

Name locations of chest leads

V1 - 4th ICS, right sternum V2 - 4th ICS, left sternum V3 - between V2 and V4 V4 - 5th ICS MCL V5 - 5th ICS anterior axillary line V6 - 5th ICS mid axillary line

27

V1 and V2 represent ... aspect of heart

septal

28

V3 and V4 represent ... aspect of heart

anterior

29

V5 and V6 represent ... aspect of heart

lateral

30

Inferior aspect of heart is represented by leads...

II, III, aVF