Arrythmias: clinical correlation

Question 1

How is sinus rhythm identified on an ECG?

Answer 1

Small positive p waves

Question 2

What is respiratory sinus arrhythmia?

Answer 2

Pressure decreases- air flows into lungs- draw blood into heart from great veins- autonomic NS detects- changes vagus nerves so less active
Sinus node fires at variable rate- speeds up during inspiration, slows down during expiration

Question 3

What is sinus tachycardia?

Answer 3

Sinus node fires greater than 100 beats per min

Question 4

What causes tachycardia?

Answer 4

Physiological= anxiety, exercise
Pathological= fever, anaemia, hyperthyroidism, heart failure, many others

Question 5

What is sino-atrial disease?

Answer 5

Mixture of sinus tachycardia, bradycardia and atrial ectopic beats, atrial fibrillation
Degenerative- scar/ fatty tissue replaces muscle

Question 6

What is the treatment for sino-atrial disease?

Answer 6

Permanent pacemaker to prevent slow rhythms
Antiarrhythmic drugs (digoxin amiodarone) to prevent rapid rhythms

Question 7

What is sinus bradycardia?

Answer 7

Sinus node fires less than 60 beats per min

Question 8

What are the causes of sinus bradycardia?

Answer 8

Physiological- sleep, athletic training
Pathological- hypothyroidism, hypothermia, sinus node disease, raised intracranial pressure (bleeding= brain stem pushed down- parasympathetic NS)

Question 9

Describe 1st degree AV nodal block

Answer 9

Long PR interval

Delay to conduction

Question 10

Describe 2nd degree AV nodal block

Answer 10

Wenkeback conduction

QRS dropped

Question 11

What are the causes of AV nodal block?

Answer 11

Sino-atrial disease
Coronary heart disease (not enough blood supply)
Aortic valve disease (close to AVN calcification)
Damage during heart surgery (inflammation- damage to AVN)
Drugs (beta blockers, digoxin, calcium channel blockers)

Question 12

Treatment for AV nodal block

Answer 12

Remove any triggering cause (drugs)
Atropine (blocks para vagus nerves) or isoprenaline (acute treatment)
Permanent pacemaker

Question 13

What are the causes of atrial flutter/ fibrillation?

Answer 13

Sino-atrial disease
Coronary heart disease
Valve disease (mitral)
Hypertension
Cardiomyopathy
Hyperthyroidism
Pneumonia, lung pathology

Question 14

What is the treatment for atrial flutter/ fibrillation?

Answer 14

Drug to block AVN and therefore limit heart rate (digoxin or beta blocker)
Electrical cardioversion (shock across chest under anaesthetic)
Catheter ablation

Question 15

What is the treatment for ventricular fibrillation?

Answer 15

Defibrillation
Antiarrhythmic drugs
Remove any triggering cause
Implantable defibrillator for some patients