Cardiac Devices

Question 1

What are the indications for pacemaker insertion?

Answer 1

1. Symptomatic bradycardia (non-reversible cause)
2. Asymptomatic bradycardia with complete heart block
3. Bi- and tri-fascicular block and recurrent unexplained syncope
4. Neurocardiogenic syncope (vasovagal) that is extreme cardioinhibitory and failed conservative therapy
5. CHF with LBBB as cardiac resynchronisation therapy

Note:
Bifascicular block = RBBB + LAFB or LPFB
Trifascicular block = RBBB + LAFB + LPFB

Question 2

What are the indications for ICD?

Answer 2

Primary prevention:

1. At risk of sudden cardiac death due to genetic disorders (LQTS, HCM, Brugada syndrome, arrhythmogenic right ventricular cardiomyopathy, catecholaminergic polymorphic VT)
2. Post MI (at leas 40 days after) and LVEF ≤35% with NYHA class 2 or 3
   * *No mortality benefit in non-ischemic cardiomyopathy pt with reduced EF**

Secondary prevention - previous cardiac arrest/ventricular arrhythmia

Question 3

What is CRT?

Answer 3

Cardiac resynchronisation therapy results in coordinated septal and free wall contraction and improved pumping efficiency
Improves HF symptoms/NYHA class, improve functional capacity, reduced mortality

Question 4

What are the indications for CRT?

Answer 4

On guideline directed medical therapy
LVEF ≤35%
Wide QRS >150 with LBBB (no benefit if QRS <120 i.e. narrow QRS)
NYHA class 2 to ambulatory 4 symptoms

Question 5

What are the two different types of 2nd degree AV block?

Answer 5

Mobitz type 1 (Wenckebach block) - progressive PR interval prolongation prior to non-conducted P wave. First P wave after block conducts to ventricle with a shorter PR interval compared to the last P wave before block

Mobitz type 2 - prolonged PR interval remains unchanged prior to P wave that fails to conduct to ventricle (i.e. no QRS complex)