Tachyarrhythmias

Question 1

Define tachyarrhytmia

Answer 1

henever the heart rate is >100 for three beats or more a tachyarrhytmia is said to be presen

Question 2

How are tachyarrhythmias categorised?

Answer 2

Narrow complex tachycardia
Broad complex tachycardia

Supraventricular and VT

Question 3

Give four ways in which SVTs can be differentiated from VTs

Answer 3

• The width of the QRS complex
• The morphology and rate of the p waves
• The relationship between the P waves and the QRS complexes
• Response of the rhythm to vagal manouevres such as carotid sinus massage

Question 4

Define narrow complex tachycardia

Answer 4

ECG rate >100, QRS complex

Question 5

GIve four forms of regular narrow complex tachycardia

Answer 5

Sinus tachycardia (normal)
Atrial tachyarrhytmias (Flutter, fibrillation) 
Junctional tachycardia 
AV node re-entry 
Accessory pathyway

Question 6

Give three irregular forms of narrow complex tachycardia

Answer 6

• Atrial fibrillation
• Atrial flutter
• Re-entrant tachycardia

Question 7

Define a broad complex tachycardia

Answer 7

ECG >100, QRS complexes >120ms

Question 8

Give three types of broad complex tachycardia

Answer 8

• VT
• SVT with BBB
• Torsades de pointes

Question 9

What are three ways in which tachyarrhytmias are produced

Answer 9

• Accelerated automacity
• triggered activity
• re-entry looping

Question 10

Give five causes of VT

Answer 10

• Metabolic
• IHD
• Cocaine
• Cardiomyopathy
• MI

Question 11

Give five causes of SVT

Answer 11

• IHD
• Thyrotoxicosis
• Caffeine
• Alcohol
• Smoking

Question 12

Give 6 causes of AF

Answer 12

o	Mitral valve disease 
o	Hypertension
o	Lung disease
o	Post op 
o	Pericardial disease
o	Cardiomyopathy

Question 13

Outline the management of regular SVT (6 steps)

Answer 13

• ABC + O2 + IV access
• Vagal manoeuvres
• Adenosine
• Help help help
• Antiarrhytmic
• DC cardioversion if haemodynamically unstable

Question 14

Outline the management of irregular SVT

Answer 14

Probable atrial fibrillation
Control rate with:
B blocker IV or digoxin IV
If onset

Question 15

How do you manage a broad complex tachycardia?

Answer 15

• ABC if pulseless
• No adverse signs
  o Amiodarone
  o K+/Mg2+ if needed
  o Sedation and DC cardioversion
• Adverse signs
  o Sedation
  o DC cardioversion
  o Amiodarone/Lidocaine

Question 16

Give the indication for DC cardioversion

Answer 16

, any patient with narrow or wide QRS complex tachycardia (ventricular rate >150) who is unstable (eg, chest pain, pulmonary edema, lightheadedness, hypotension) should be immediately treated with synchronized electrical cardioversion.[6]
Synchronized electrical cardioversion may also be used to treat stable VT that does not respond to a trial of intravenous medications. It is also recommended for the treatment of the following[7] :
Supraventricular tachycardia due to reentry
Atrial fibrillation
Atrial flutter
Atrial tachycardia
Monomorphic VT with pulses

Question 17

How does adenosine work?

Answer 17

When it is administered intravenously, adenosine causes transient heart block in the atrioventricular (AV) node. This is mediated via the A1 receptor, inhibiting adenylyl cyclase, reducing cAMP and so causing cell hyperpolarization by increasing outward K+ flux. It also causes endothelial-dependent relaxation of smooth muscle as is found inside the artery walls.