Heart block and other conduction failures

Question 1

First Degree

Answer 1

PR interval > 5 little boxesA
All P waves followed by QRS
Often asymptomatic
Delayed AV node transmission

Question 2

Type 1 Second Degree

Answer 2

PR interval gets longer until QRS wave fails to follow P wave
Likely cause AV node damage

Question 3

Type 2 Second Degree

Answer 3

Some P waves blocked and not followed by QRS
PR interval remains the same
Problem in Bundle of His
Treatment: implant pacemaker

Question 4

Third Degree

Answer 4

Atrial signals consistently fail to arrive at ventricles
Consistent ventricular rate 30-40 bmp 
PR interval varies radically 
Intrinsic Ventricular rate (<60 bpm)
Atrial beats consistent

Question 5

Escape Beats

Answer 5

Late
Triggered by natural rhythmicity of non-atrial tissue
Occur when atrial signal is delayed

Question 6

Premature Beats

Answer 6

Early
Due to irritable tissue
Triggered often in ventricular tissue or by AV node - ectopic beats

Question 7

Atrial Fibrillation

Answer 7

Disorganised electrical activity in atria
No P wave - flat wiggly line instead
Fast and irregular ventricular rate - Many signals reach AV node
Common in elderly
Stroke risk - can lead to thrombus formation

Question 8

ST segment Elevation

Answer 8

Interval = duration from start of x to end of y
Segment = from end of x to start of y
ST segment - end of QRS to start of T - elevation = sign of acute MI
Isoelectric baseline - end of T to next P

Question 9

Premature ventricular contraction

Answer 9

Unusually wide, weird-looking ventricular electrical activity
No S wave - instead a wide negative dip where T wave should be
Often beat triggered in middle of myocardium - ventricles electrically unsynchronised
Delayed inefficient conduction

Question 10

Respiratory Sinus Arrythmia

Answer 10

Heart beat faster on inspiration than expiration
Children and athletes
Observe ventricular rate - inverse of RR interval