Arrythmias- narrow tachy

Question 1

What are the types of AF?

Answer 1

Acute (lasts <48 hours)
Paroxysmal (lasts <7 days and is intermittent)
Persistent (lasts >7 days but is amenable to cardioversion)
Permanent (lasts >7 days and is not amenable to cardioversion)

Question 2

What does ‘fast’ AF refer to?

Answer 2

Rate of AVN conduction.

Fast= fast ventricular rate

Question 3

When is AF not irregular?

Answer 3

AF is ALWAYS irregular except in: complete heart block

Question 4

What is an irregularly irregular pulse indicative of?

How can you differentiate between diagnoses?

Answer 4

AF or ventricular ectopics
When the HR increases to a certain point, ectopics stop, meaning the pulse becomes regular during exercise if it is due to ventricular ectopics.

Question 5

What investigation is used to diagnose AF?

Answer 5

ECG

Question 6

What score is used after diagnosis of AF? Why?

Answer 6

CHAD2VASC score
Used to quantify risk of thromboembolic event, and advises on necessity of anticoagulation
Or, HAS BLED score

Question 7

How is AF managed?

Answer 7

Anticoagulation to prevent stroke or PE- DOAC unless CKD, then warfarin
Rate control- beta blocker and/or digoxin (not useful in paroxysmal)
Rhythm control (sometimes)- cardioversion

Question 8

What are some cardiac causes of AF?

Answer 8

Ischaemic heart disease
Hypertension
Rheumatic heart disease (typically affecting the mitral valve) (most common cause in less developed countries)
Peri-/myocarditis

Question 9

What are some non-cardiac causes of AF?

Answer 9

Dehydration
Endocrine causes (such as hyperthyroidism)
Infective causes (such as sepsis)
Pulmonary causes (such as pneumonia or pulmonary embolism)
Environmental toxins (such as alcohol abuse)
Electrolyte disturbances (such as hypokalaemia, hypomagnesaemia)

Question 10

How do you assess for haemodynamic instability?

Answer 10

Assess for haemodynamic stability:
Shock (suggests end organ hypoperfusion)
Syncope (evidence of brain hypoperfusion)
Chest pain (evidence of myocardial ischaemia)
Pulmonary oedema (evidence of heart failure)

Question 11

How do you manage a person with AF that is haemodynamically unstable?

Answer 11

Immediate cardioversion

Question 12

What is the mechanism of SVT?

Answer 12

Supraventricular tachycardia (SVT) is caused by the electrical signal re-entering the atria from the ventricles.

Question 13

What is paroxysmal SVT?

Answer 13

Paroxysmal SVT describes a situation where SVT reoccurs and remits in the same patient over time.

Question 14

What are the types of SVT? Briefly describe them

Answer 14

AVNRT- Atrioventricular nodal re-entrant tachycardia” is when the re-entry point is back through the AV node.
AVRT- “Atrioventricular re-entrant tachycardia” is when the re-entry point is an accessory pathway (Wolff-Parkinson-White syndrome).
Atrial tachycardia- is where the electrical signal originates in the atria somewhere other than the sinoatrial node. This is not caused by a signal re-entering from the ventricles but instead from abnormally generated electrical activity in the atria. This ectopic electrical activity causes an atrial rate of >100bpm.

Question 15

When is direct current (DC) shock indicated in SVT?

Answer 15

When adverse features are present, they can be remembered with HISS pneumonic:
Heart failure
Ischaemia
Shock
Syncope

Question 16

What are some complications of SVT?

Answer 16

Syncope
Deep vein thrombosis
Embolism
Cardiac tamponade
Congestive cardiac failure
Myocardial infarction
Death

Question 17

What monitoring does a person with a stable SVT require?

Answer 17

Continuous ECG monitoring

Question 18

Describe the stepwise approach to SVT management

Answer 18

Valsalva manoeuvre. Ask the patient to blow hard against resistance, for example into a plastic syringe.
Carotid sinus massage. Massage the carotid on one side gently with two fingers.
Adenosine
An alternative to adenosine is verapamil (calcium channel blocker)
Direct current cardioversion may be required if the above treatment fails

Question 19

What features of an ECG indicate AVNRT

Answer 19

No p waves
T waves that peak just prior to QRS complex- not to be confused with p waves
Usually 140-180 bpm, can be up to 250.
If p waves are visible (rarely as the QRS hides them) they are inverted and seen just after the QRS

Question 20

What features of an ECG can be seen in AVRT (orthodromic)?

Answer 20

160-250 bpm

Inverted p waves can be seen more commonly here