Pacemakers & Prosthetic Valves Flashcards
Briefly summarise how pacemakers work
- Deliver controlled electrical impulses to specific areas of heart to restore normal electrical activity and hence improve heart function
- Consist of:
- Pulse generator: generates electrical impulse. Implanted under skin commonly in left anteriro chest wall or axilla
- Pacing leads: carries impulse to relevant chambers of heart
- Modern pacemakers monitors the natural electrical activity of heart and only activates/intervenes when electrical activity is abnormal
How long do batteries on pacemaker typically last?
5yrs
Pacemakers may be contraindications in….
- MRI scans (although modern ones are often MRI compatible)
- TENS machiines
- Diathermy in surgery
Pacemakers do not need to be removed before cremation; true or false?
FALSE; they must be removed before cremation and hence it must be noted on the cremation form whether pt had a pacemaker and if it has been removed
State some indications for pacemakers
- Symptomatic bradycardia
- Mobitz type II AV block
- Third degree heart block
- Severe heart failure (CRT)
- Hypertrophic obstructive cardiomyopathy (ICDs)
Pacemakers can be single, dual or triple-chamber. For a single chamber pacemaker, discuss:
- Who used in
- Where leads are placed
- Used in pts with abnormal SA or AV node
- Leads in a single chamber: RA or RV
- Placed in RA if AV conduction is normal and issue is with SA node
- Placed in RV if AV conduction is abnormal
Pacemakers can be single, dual or triple-chamber. For a dual chamber pacemaker, discuss:
- Who used in
- Where leads are placed
- Abnormality is SA and AV node therefore need pacing in both RA and RV
- Leads in RA & RV
Pacemakers can be single, dual or triple-chamber. For a triple chamber pacemaker, discuss:
- Alternative name
- Who used in
- Where leads are placed
- Cardiac resynchronissation therapy (CRT) pacemakers
- Used in heart failure
- Leads in RA, RV and LV
What are ICDs?
- Implantable cardiac defibrillators
- Continually monitor heart and apply defibrillator shock to cardiovert pt back to sinus rhythm if they identify a shockable arrhythmia
Discuss what you would see on ECG if a pt has a:
- Single chamber pacemaker
- Dual chamber pacemaker
- Triple chamber (cardiac resynchronisation) pacemaker
- Single chamber: pacing spike either before the p or QRS
- Dual chamber: pacing spike BOTH before the p and before QRS
- Triple chamber: same as above
If a pt has the following scar what procedure does it indicate they have had:
- Midline sternotomy
- Right sided mini-thoracotomy
- Midline sternotomy:
- mitral valve replacement
- aortic valve replacement
- CABG
- Right sided mini-thoracotomy
- mitral valve replacement (minimally invasive)
Valve replacements can either be bioprosthetic or a metallic mechanical valve. Discuss the lifespan of each
- Bisprosthetic: 10yrs
- Metallic mechanical: well over 20yrs
What must a pt be on lifelong if they have a mechanical metallic valve?
Anticoagulation with lifelong warfarin
INR target 2.5-3.5
State, and briefly describe, the 3 types of mechanical metallic valve
-
Starr-Edwards valve
- Ball in cage
- Very sucessful but no longer being implanted
- Highest risk of thrombus formation
-
Tilting disc valve
- Single tilting disc
-
St Jude valve
- Two tilting metal discs
- Two discs means they are called bileaflet valve
- Least risk of thrombus formation
State some potential complications of mechanical heart valves
- Thrombus formation
- Infective endocarditis
- Haemolysis causing anaemia
Remind yourself what a TAVI is, include:
- When it is done
- How it is done
