ECG Abnormalities

Question 1

How does atrial fibrilation appear on an ECG?

Answer 1

• No P waves
• Ireggeulary irregular R-R intervals
• Normal QRS (not all conducted through AV node)

Due to origionation of impulses from multiple atrial foci.

Question 2

What are the types of heart block?

Answer 2

1st degree 
2nd degree (type 1 and 2)
Third degree (complete)

Question 3

How does First degree heart block appear on an ECG?

Answer 3

• Normal P wave
• Followed by QRS complexes

Greater than .2 seconds

Question 4

How does Second degree type 1 AV block appear?

Answer 4

-Successivly longer PR intervals untill a QRS complex droopped

Electrial signal not conducted through AV to ventricles (dropped beat)

Question 5

How does second degree type 2 heart block appear on an ECG?

Answer 5

• PR interval not lengthened
• Sudden dropped QRS comolex

P waves (artial rhythm) regualr 
Ventricular rhythm irregualr

Question 6

How does 3rd degree heart block appear on an ECG?

Answer 6

Artia and ventricles depolarising independantly (AV conductance failure)

• Wide QRS complex
• No link between P waves and QRS complexes

Question 7

How does Ventricular fibrilation appear on an ECG?

Answer 7

• Abnormal, chaotic and vast ventricular depolarisation
• Ventricles quiver

Impusles from ectopic sites in ventricles
No coordinated contaction/ CO

Question 8

How do ventricular ectopic beats appear on an EGC?

Answer 8

• Wide QRS complex
• No preceeding P wave

Premature ventricular ectopic beats (PVCs)

Question 9

When does ventricular tachycardia occour?

Answer 9

When there is a run of 3 consecutive PVCs

Question 10

What does polymorphic Vtach look like?

Answer 10

• Gradual change in amplitude of QRS complexes

- QRS complexes twisting around an iselectric point

Question 11

How does an ECG change in hypokalamia?

Answer 11

• Increased amplitude and width of P wave
• Prolonged PR interval
• T wave flattening and inversion
• ST depression
• U waves

Question 12

How does an ECG change is hyperkalaemia?

Answer 12

• Tall T waves
• Loss P wave
• Widening QRS complex
• QRS continues to widen

Question 13

When does ST elevation occour?

Answer 13

Complete occlusion of coronary artery
Full thickness myocardium involved
ST segement Elevation MI (STEMI)

Question 14

What are the ECG changes on a STEMI?

Answer 14

• Tall peaked T waves (early)

- ST elevation (above isoelectric point in leads facing damaged area)

Question 15

Short vs long changes in STEMI ECG?

Answer 15

Acute;

• Hyper actute T waves to T wave inversion
• ST elvations (goes in days)
• ST depressions (normally resolve with time

Chronic;
-Pathological QRS complesex arise

Question 16

What are ECG changes in a non STEMI?

Answer 16

• ST segment depression

- T wave inversion

Question 17

What ECG changes occour in ischeamia (unstable angina)?

Answer 17

• ST segment depression
• T wave inversion

Same as non STEMI

Question 18

What ECG changes occour in stable angina?

Answer 18

• ST depression during exercise
• ECG changes reverse at rest
• (down sloping of St segment depression/elevation)

Question 19

What changes ECG occour as result of previous MI?

Answer 19

Pathological Q waves
Negative deflection preceding R wave

No electrical activity in dead tissue
No apots in dead tissue
ECG looks though dead tissue (picks up electrical activity from opposite side of infarct)

Question 20

How to tell the difference between ischeamia/ non STEMI?

Answer 20

Blood tests

Troponin present in non STEMI but not in icheamia

Question 21

How to tell area of heart effeted on STEMI ECG?

Answer 21

Damaged tissues come towards electrode

Question 22

How to tell area of heart affected in non STEMI/ischaemia?

Answer 22

Abnormal current transversing damaged tissue is moving away from recording electrode