Bradycardia and Pacing

Question 1

Aetiology of bradycardia

Answer 1

Common
Can be physiological
-Sinus bradycardia in athletes
-Vagal stimulation
=Diving
=Carotid sinus massage
=Medical procedures (colonoscopy)

Question 2

Pathophysiology of bradycardia

Answer 2

-Bradyarrhythmia
=Pathological bradycardia
=Commonly Sinus node and AV node

-Fibrosis of conducting pathway
=Age
=Infiltrative disorders (sarcoidosis, amyloidosis, haemochromatosis)

-Direct Damage to conducting system (AVN)
=AV surgery/TAVI
=Aortic Valve Endocarditis
=Cardiac Ablation

-Ischemia
=Commonly RCA territory
-Electrolyte abnormalities (potassium)
-Infection
=Lyme disease

Question 3

Common bradyarrythmias

Answer 3

-Sino atrial disease (sick sinus syndrome= p waves conducted)
-AV block most common
=1st degree AV block: Long PR interval >200ms, Normal PR interval 120-200ms
=2nd degree AV block: Mobitz 1 – Wenkeback (Progressive PR prolongation until QRS complex is dropped)/ Mobitz 2 - 2:1/3:1 etc
=3rd degree AV block: CHB/ Complete disassociation of A-V conduction

Question 4

Symptoms of bradycardias

Answer 4

-Can be asymptomatic
=Sinus Bradycardia, 1st degree AV block
-Pre-syncope
-Collapse and Syncope
-Heart Failure Symptoms (complete heart block)
=Breathlessness
=Reduced Exercise tolerance
=Fatigue
-Cardiac Arrest

Question 5

Clinical signs of bradycardias

Answer 5

-Low Pulse rate
-Hypotension (acute)
-Signs of Heart Failure
=Peripheral oedema
=Pulmonary oedema
-Cannon A waves
=CHB
=Atria contracting against closed AV valve

Question 6

Investigations in bradycardias

Answer 6

-12 lead ECG
=Often need a longer rhythm strip
=Look for ischemia

-ECHO
=AV disease
=Hypertensive heart disease
=Cardiomyopathy
=To direct treatment

-MRI
=If suspicion of sarcoidosis/amyloidosis

-Bloods
=? Endocarditis
=Lyme serology if appropriate
=Ferritin levels

Question 7

Treatment of bradycardias

Answer 7

-Initial management
=Supportive
=Reverse causes: Electrolytes/ Stop rate limiting medications/ Fluid resuscitation if appropriate

-Drugs
=No long term therapeutic options
=Short term, in hospital
=Atropine
=Isoprenaline (beta agonist)
=Adrenaline/noradrenaline
=Inotropic agents

-Pacemaker
=Transcutaneous
=Transvenous (emergency)

Question 8

Complications of pacemakers

Answer 8

5%

-Pneumothorax
-Tamponade
-Lead displacement
-Arrhythmias

-Long term complications
=Infection
=Lead fracture