QRS abnormalities, ectopic beats, pacemakers

Question 1

Atrial ectopic beats

Answer 1

Early, abnormally shaped P wave followed by premature QRS
Pause after early beat
P wave may be buried in T wave

Question 2

Ventricular ectopic beats

Answer 2

Abnormal beat originating from ventricles
delayed next beat
broad QRS, no preceding P wave
Different morphology

Question 3

Complex ventricular ectopics

Answer 3

Pairs- couplet
Threes- triplet
Run- salvo
sinus-ectopic-sinus = bigeminy
>/= 3 ectopics = non sustained VT is terminates after 30s
each ectopic has different morphology- multifocal ectopic beats

Question 4

Causes of left axis deviation

Answer 4

Left anterior hemi-bundle block

LVH

Question 5

Causes of right axis devitation

Answer 5

Left posterior hemi block
RVH
Pulmonary hypertension
anterolateral MI
PE

Question 6

Bundle branch block

Answer 6

Broad QRS
abnormal shape

Partial BBB if QRS is not wide enough

Question 7

Left BBB

Answer 7

Broad QRS (>120 ms)
no Q waves in V5 and V6

Question 8

Right BBB

Answer 8

QRS >120 ms

R’ in V1 (rabbit ear)

Question 9

Trifascicular block

Answer 9

RBBB + axis deviation + first degree AV block
Conduction tissue disorder
Risk of complete heart block

Question 10

Prolongued QT

Answer 10

Measured from start of QRS to end of T
QTc >/= 460 ms in F >/= 450 in M
Risk of VT / torsades

Question 11

Causes of prolongued QT

Answer 11

Channelopathy
Congential
Antiarrhythmics
antiepileptics
Antipsychotics
Antibiotis
Hypokalaemua
Hypomagnesemia
Cardiac disease
Diabetes
Alcohol liver disease

Question 12

Short QT

Answer 12

<390 s
Digoxin
Hypercalcemia
congenital
risk of life threatening arrhythmia

Question 13

LVH

Answer 13

ST depression
T wave flatteing or inversion
V6 V5 I or aVL

Question 14

RVH

Answer 14

RAD
Peaked P waves
Partial/compete RBBB
Dominant R waves (V1-V3)
Dominant S waves (V5-V6)
T wave inversion/ST depression V1- V4

Question 15

Pacemaker

Answer 15

Verticle artifact- pacing spike

QRS may be broad

Question 16

Pacemaker malfunction

Answer 16

Pacing spike is not aligned with P or QRS = failure to capture
Pacing spike on top of QRS = failure to sense

Question 17

Causes of pacemaker malfunction

Answer 17

dislodgment 
displacement
damage
inappropriate programming
MI
Hyperkalaemia

Question 18

Normal variant T wave inversion

Answer 18

In limb leads
If QRS is upright- T wave should be upright and if QRS is negative T wave should be negative
QRS biphasic then T wave can be either - or + but should be small