Arrhythmias

Question 1

What are the ECG changes in first degree heart block?

Answer 1

Prolonged PR in isolation

Question 2

ECG changes in 2nd degree Mobitz type 1?

Answer 2

progressively prolonged PR intervals with complete drop of QRS, return to sinus/previous pattern

Question 3

ECG changes in 2nd degree Mobitz type 2?

Answer 3

three consecutive P waves may be followed by a QRS complex, giving the ECG a normal appearance, then the fourth P wave may suddenly not be followed by a QRS complex since it does not conduct through the AV node to the ventricles.The PR interval may be normal or prolonged, however it is constant in length unlike second-degree AV block Mobitz Type I (Wenckebach) in which the PR interval progressively lengthens until a P wave is not conducted.

Question 4

Are type 1 and type 2 mobitz reversible?

Answer 4

type 1 is however type 2 is not, therefore pacemaker required

Question 5

When can QRS complex be increased and decreased in amplitutde?

Answer 5

incr- LVH, can be normal

decr- fluid overload

Question 6

What are deep Q-waves a sign of?

Answer 6

previous MI damage

Question 7

How should normal R-wave progression appear across ECG leads? What can poor R wave progression be a sign of?

Answer 7

it should increase throughout the leads. ? MI

Question 8

When is ST elevation significant?

Answer 8

if >1 in limb leads, >2 in chest leads

Question 9

What are U-waves pathognomonic of?

Answer 9

hypokalaemia

Question 10

Which drugs increase QT interval?

Answer 10

Antipsychotics, TCAs, antiarrhythmic drugs

Question 11

You see ST depression in anterior leads V1-V3. What are you worried about?

Answer 11

posterior STEMI

Question 12

What is the evidence on ECG of right heart strain?

Answer 12

RBBB, r.axis deviation, T-wave inversion

Question 13

What are findings of PE in ECG?

Answer 13

tachycardia and S1Q3T3 (only occus in 10% of people)

Question 14

Example of supraventricular tachycardia?

Answer 14

atrial flutter

Question 15

What is the AV ratio in atrial flutter and what heart rate does this give rise to?

Answer 15

2:1, 150bpm (3:1, 4:1 can happen as well, therefore 300 bpm or 450 bpm!)

Question 16

Where does the re-entry circuit arise in atrial flutter?

Answer 16

right atrium

Question 17

List three causes of hyperkalaemia

Answer 17

1. Increased intake- potassium supplements, excess in diet
2. Excessive endogenous- rhabdomyolysis, extensive burns, tumour lysis syndrome, trauma, haemolysis
3. Redistribution (shift from intra to extracellular) e.g. acidosis, insulin deficiency, drugs
4. Diminished potassium excretion e.g. AKI, drugs

Question 18

Which drugs can result in hyperkalaemia?

Answer 18

ACEi, NSAIDs, K+ sparring -> reduce potassium excretion

Beta blockers and digoxin -> alter transmembrane potassium movement

Question 19

A patient has an anterior STEMI. Which coronary artery is affected?

Answer 19

LAD

Question 20

Inferior STEMI, which coronary artery?

Answer 20

R coronary A

Question 21

Lateral STEMI. Which coronary artery?

Answer 21

L circumflex

Question 22

List three causes of a prolonged QTc?

Answer 22

TIMME
  Toxins/drugs
  Inherited: e.g. Romano-Ward, Jervell (c¯ SNHL) 
  Ischaemia 
  Myocarditis 
  Mitral valve prolapse 
  Electrolytes: ↓Mg, ↓K, ↓Ca, ↓ temp

Question 23

List two drugs that prolong the QTc interval

Answer 23

• Macrolides
  antiarrhythmics: amiodarone
• TCAs
• Histamine antagonists

Question 24

List one causes of shortened PR interval?

Answer 24

accessory conduction e.g. WPW

Question 25

In which leads are T waves inverted normally? In which leads would T wave inversion be absolutely abnormal

Answer 25

aVR and V1 Abnormal in LI LII V4-V6

Question 26

List two causes of abnormal T wave inversion

Answer 26

``` Strain ischaemia ventricular hypertrophy BBB digoxin ```

Question 27

When are U waves observed?

Answer 27

Hypokalaemia (following T waves)

Question 28

When are J waves observed?

Answer 28

SAH hypercalcaemia hypothermia positive deflections occurring at the junction between the QRS complex and the ST segment

Question 29

What are the features of WPW on EGC?

Answer 29

slurred upstroke of QRS= delta wave, usually in V3/V4 Shortened PR intervals

Question 30

What are two features on ECG of brugada syndrome

Answer 30

RBBB ST elevation in V1-V3

Question 31

Name three features on ECG of hyperkalaemia

Answer 31

Tall tented T waves Widened QRS Absent P waves

Question 32

What are two features of PE on ECG?

Answer 32

SI QIII TIII - deep S wave in I (RAD) - pathological Q in III - T inversion in III Right vent strain - RAD (S wave in I) - Dominant R wave and T wave inversion in V1-V3

Question 33

Two features of hypokalaemia?

Answer 33

Small T waves ST depression Prolonged QT interval Prominent U waves

Question 34

List three causes of bradycardia

Answer 34

``` DIVISIONS Drugs Ischaemia Vagal hypertonia Infection Sick sinus syndrome Infiltration (autoimmune, sarcoid, amyloid) O- hypOthyroidism, hypOkalaemia Neuro (Incr ICP) Septal defect Surgery or catheterisation ```

Question 35

State two drugs that can cause bradycardia

Answer 35

 Antiarrhythmics (type 1a, amiodarone)  β-blockers  Ca 2+ -channel blockers (verapamil)  Digoxin

Question 36

List two infections that cause bradycardias

Answer 36

 Viral myocarditis  Rheumatic fever  Infective endocarditis

Question 37

What is the medical treatment for bradycardia?

Answer 37

atropine 0.6-1.2 mg IV, isoprenaline IV

Question 38

What is the definitive treatment for bradycardias?

Answer 38

pacemaker insertion

Question 39

When do you not need to treat a bradycardia?

Answer 39

If asymptomatic and rate <40

Question 40

Differentials for narrow complex tachycardia? (SVT)

Answer 40

``` Sinus tachy AF Atrial flutter AVNRT AVRT ```

Question 41

If tachyarrhythmia is ID as non AF i.e. regular rhythm, how should management proceed of patient?

Answer 41

 Continuous ECG trace  Vagal manoeuvres  Adenosine 6mg IV bolus  Then 12mg, then 12mg

Question 42

If tachyarrhythmia is AF what is the treatment?

Answer 42

Control rate with beta blocker or digoxin If onset <48 hr then cardioversion with amiodarone or DC shock Consider anticoagulation with heparin

Question 43

What is the mechanism of action of adenosine?

Answer 43

temporary block of AVN

Question 44

Why do you give adenosine for SVT?

Answer 44

unmasks atrial rhythm, cardioverts AVNRT/AVRT to sinus rhythm

Question 45

If adenosine doesn't work in treating SVT, what other options do you have?

Answer 45

Digoxin, atenolol, verapamil, amiodarone

Question 46

What are the contraindications of adenosine?

Answer 46

asthma, 2/3rd degree heart block

Question 47

List two differentials for broad complex tachycardias

Answer 47

VT Torsades de pointes SVT with BBB

Question 48

Three causes of VT?

Answer 48

``` Infarction Myocarditis Valve abnormality Iatrogenic: digoxin, antiarrhytmic drug Cardiomyopathy Electrolyte imbalances: hypokalaemia, low Mg, hypoxia, acidosis ```