Bradycardias

Question 1

What is a bradycardia?

Answer 1

A HR below 60BPM.

Question 2

What symptoms can present?

Answer 2

• Often asymptomatic
• Fatigue, nausea, dizziness
  Concerning symptoms
• Chest pain (myocardial ischaemia)
• Syncope
• Breathlessness (pulmonary oedema)
• Shock (<90BP, pallor, sweating, cold)

Question 3

What are the types of bradycardia?

Answer 3

• Sinus bradycardia
• Junctional bradycardia
• Heart block (1,2,3 degree, LBBB, RBBB, TFB)
• AF with slow ventricular response
• Atrial flutter with a high degree block

Question 4

What is junctional bradycardia?

Answer 4

A cardiac rhythm that arises from the AV node with a HR of <60bpm.

• Has a flat baseline with no obvious P waves
• The P wave can sometimes be seen in the ST segment

Question 5

What are the physiological causes of bradycardia?

Answer 5

Asymptomatic trained athletes can have a HR of 40bpm at rest, and 30bpm at sleep

Question 6

What are cardiac causes for bradycardia?

Answer 6

• Degenerative changes causing fibrosis of conduction pathways (elderly patients aka sick sinus syndrome)
• Post MI (inferiorly as RCA supplies SA node and AV node)
• Sick sinus syndrome
• Iatrogenic eg surgery
• Aortic valve disease eg infective endocarditis
• Myocarditis, cardiomyopathy, amyloid, sarcoid, SLE

Question 7

What are the non cardiac causes of bradycardia?

Answer 7

• Vasovagal
• Hypothyroidism or adrenal insufficiency
• Hyperkalaemia or hypoxia
• Hypothermia
• Raised ICP (cushings triad of bradycardia, hypertension, irregular breathing)

Question 8

What drugs cause bradycardia?

Answer 8

Beta blockers
Amiodarone
Verapamil
Diltiazem
Digoxin

Question 9

What is vasovagal syncope?

Answer 9

• Reflex bradycardia and peripheral vasodilation provoked by emotion, pain or standing too long
• Think of it as ‘vagal’ = parasympathetic

Question 10

What is the emergency management for a bradycardic patient with adverse signs?

Answer 10

Atropine 500mcg IV

Question 11

What can be given if bradycardia is caused by beta blocker/CCB?

Answer 11

Glucagon

Question 12

What investigation can be done for vasovagal syncope?

Answer 12

Tilt table testing

Question 13

What investigations can be done for acute bradycardias?

Answer 13

1. 12 lead ecg
2. Manual BP
3. U+E’s for electrolyte abnormalities
4. Digoxin levels

Question 14

What temporary paving can be given in an acute setting?

Answer 14

1. Transcutaneous pacing - Emergency. Completed using a defibrillator and chest pads.
2. Epicardial pacing - Cardiothoracic surgery
3. Transvenous pacing - Single pacing wire inserted into right ventricle under fluoroscopic guidance (X-rays).

Question 15

What investigations can be done for bradycardias?

Answer 15

• Medication reviews
• TFT’s
• FBC, U+E (Ca and Mg)
• Glucose
• 24hr ECG

Question 16

What is a sinus pause?

Answer 16

A transient absence of P waves that lasts from 2 seconds to several minutes, due to failure of SAN to initiate activity.
May be followed by a normal rhythm, a junctional escape or a ventricular escape rhythm.

Question 17

What is tachy-brady syndrome?

Answer 17

Alternating bradyarrhythmia with tachyarrthymia.
eg sinus pause with AF + fast ventricular response.
Due to sick sinus syndrome.

Question 18

What is the definitive treatment for bradycardias?

Answer 18

• Permanent pacing, inserted in the upper left chest wall transvenously.

Question 19

What types of pacemaker are there?

Answer 19

Single chamber - Into right atrium/ventricle
Dual chamber - Into right atrium and right ventricle
Biventricular chamber - LV and RV, used in heart failure

Question 20

What is the management of first degree heart block?

Answer 20

Seen in normal people, usually no specific action is required.
Although can be seen in the context of endocarditis/LBBB etc

Question 21

What is the management of second degree heart block?

Answer 21

May require temporary/permanent pacing.

Question 22

What is the management of third degree heart block?

Answer 22

ALWAYS requires pacing.