Patient - ECG Flashcards Preview

Pharmacy Year 2 Semester 1 > Patient - ECG > Flashcards

Flashcards in Patient - ECG Deck (29):
1

Which channels, when opened, cause the polarisation of membrane?

K+ cationic gated ion channels
Voltage gated can be Ca2+ and Na+

2

Describe Ca2+ induced Ca2+ release

1) Entry of Ca2+ during plateau phase
2) Drives the release of more Ca2+ from internal stores in sarcoplasmic reticulum
3) Ca2+ binds to troponin, exposing actin to myosin
4) Actin/myosin fibres contract, using ATP

3

Describe how troponin can be a sign of a heart attack (myocardial infarction)

If cardiac myocytes are damaged then cells open and leakage of troponin occurs, troponin then is in the blood which is a sign of an MI

4

What 3 things to contractile myocytes contain?

-proteins actin and myosin make contractile fibres
-protein troponin regulates the actin-myosin crossbridges
-Sarcoplasmic reticulum - an organelle which contains stores of Ca2+

5

What are contractile fibres made of?

Actin and myosin

6

What regulates actin-myosin crossbridges?

Troponin

7

Which organelle contains stores of Ca2+?

sarcoplasmic reticulum

8

Describe how excitation-contraction coupling occurs

-Calcium-induced calcium release during the plateau occurs. Calcium enters the cell (~5%) which triggers sarcoplasmic reticulum to release calcium (~95%)
-Contraction enabled when cytosolic Ca2+ binds to troponin, making it active and capable of interacting with myosin
-Repolarisation causes relaxation of actin-myosin fibres. Active transport of Ca2+ back to SR and extracellular fluid
-Fall in cytoplasmic Ca2+ renders troponin inactive and therefore the fibres relax

9

In which cell type is the action potential driven by the opening of "fast" Na+ channels?

Contractile myocytes

10

What is an ECG?

Electroencephalogram
Non-invasive, information-rich monitoring of cardiac electrical activity
Coordinated electrical currents in the heart create small voltage differences within the body

11

What do QRS waves correspond to?

Ventricular action potentials

12

The strength of an ECG signal depends on what?

direction of depolarisation travel

13

How many leads in an ECG?

12 leads

14

P, QRS, T shape corresponds to which tissue?

Contractile

15

What does the P wave signify?

Atrial depolarisation (start contraction)

16

What does the QRS complex/wave signify?

Ventricular depolarisation (start contraction)

17

What does the T wave signify?

Ventricular repolarisation (start relaxation)

18

What factors must one look at to analyse the ECG?

-Identify QRS complex (ventricular contraction)
-Heart rate - normal? tachycardic?
-Heart rhythm - look for the P wave - normal excitation cycle? (sinus rhythm?) , does the P wave precede each QRS by a constant interval?
-Conduction problems

19

How to measure heart rate?

Measure R-->R (seconds per beat)
Convert interval to rate (bpm)
Shortcut is 300/number of large squares

20

Name 3 things to look at when checking for conduction problems

-PQ (or PR) interval - May reveal AV block (too long) or Wolff-Parkinson-White syndrome (too short- unwanted pathways)
-QRS interval - may reveal right or left bundle block
-Q-T interval - May reveal QT prolongation - failure to repolarise quickly enough

21

PQ (or PR) interval is too long, what can this signify?

AV Block

22

PQ (or PR) interval is too short, what can this signify?

Wolff-Parkinson-White syndrome

23

Which part of the ECG can reveal right or left bundle block?

QRS interval

24

Which part of the ECG can reveal failure to repolarise quickly enough?

QT interval that is too prolonged

25

What can an ECG bpm diagnose?

sinus tachycardia
sinus bradycardia

26

What does no P wave in an ECG possibly signify?

Atrial fibrilation
as artial myocutes are ectopic pacemakers

27

What does a long P-Q interval possibly signify?

First degree heart block (AV block)

28

What do missed heart beats possibly signify?

Second degree heart block

29

What is STEMI?

ST segment elevated above baseline - sign of ischaemic tissue - worst type of myocardial infarction