Arrhythmias

Question 0

What is atrial flutter? How can it be treated?

Answer 0

Atrial depolarisation: 180-350bpm

Caused by re-entry loops (can be paroxysmal - sudden and unpredictable - or transient, persistent, or permanent)

Beta-blockers, Ca2+ channel blockers, digoxin = increase AV block

Question 1

What is bradycardia? How can it be treated?

Answer 1

HR < 50bpm

Anticholinergics e.g. atropine = competitive inhibition of mAChR -> decreased vagal stimulation -> increased SAN depolarisation -> increased AVN depolarisation -> increased HR

beta-1 agonists e.g. isoprolerenol -> increased AVN conduction -> increased HR

Question 2

What is atrial fibrillation? How can this be treated?

Answer 2

Atrial depolarisation: 350-600bpm & uncoordinated contraction (therefore no atrial contraction)

Irregular irregular rhythm & no visible P waves

Can lead to decreased cardiac output:

• hypotension
• pulmonary congestion
• increased risk of thrombi formation (stasis of blood in atria)

Beta-blockers, Ca2+ channel blockers, anticoagulants

Question 3

What is ventricular fibrillation? How can it be treated?

Answer 3

Disordered, rapid stimulation of ventricles & uncoordinated contraction

Electrical defibrillation

Question 4

What is tachycardia? How can it be treated?

Answer 4

HR > 100bpm

Supraventricular: origin of problem in atria/AVN
- narrow QRS complex

Ventricular: origin of problems in ventricles
- wide QRS complex

-> long QT syndrome: early after depolarisations -> Torsades de pointes (long QT preceding arrhythmia, progressive twisting of QRS, changing amplitude of QRS, irregular RR intervals, tachycardia)

beta-blockers to prevent syncope