Pacemakers and ICD’s Flashcards
Pacemaker?
An external device that takes over as the Hearts pacemaker.
Indications of a pacemaker (why might it be needed)?
- SINUS NODE DYSFUNCTIONS:
•symptomatic bradycardia
• sinus pause/arrest
- ACQUIRED AV BLOCK:
•symptomatic mobitz 1/2
•Third degree heart block
- POST CARDIAC TRANSPLANT
- HYPERTROPHIC CARDIOMYOPATHY
-LONG QT SYNDROME
-CARDIAC RESYNCHRONISATION THERAPY.
How does a pacemaker work?
• Pulse generator ~ contains “brain” and battery
Battery lasts 5-10 years until entire device needs replacing.
• Leads ~ either screwed into the myocardium or “wedged” into trabeculae.
Fixed rate (non demand) and on demand Pacemakers?
Fixed rate = paces equally at a specific rate . Usually 67bpm
On demand= only pace when required (more commonly used)
Types of Pacemaker ?
• Single chamber = placed in Atria (near SA node) , pacemaker spike would usually show before the P wave/replace the P wave. Only 1 PACEMAKER SPIKE observed on ECG as it only sends of 1 impulse.
• Dual chamber = placed in atrium (SA node) and also ventricles (AV)
Sends 2 impulses , 1 observed before/replacing P wave, 1 observed before QRS.
• Biventricular chamber = send 1 impulse to both ventricles observed before the QRS.
What can cause appearance of pacemakers within ECG to vary?
- the pacemaker mode use
- placement of pacemaker leads
- pacemaker threshold
Causes of Broad QRS complex >0.12s?
Caused by ventricular depolarisation occurring outside of the conduction system.
What is a ‘Capture beat’ ?
When a pacemaker is normally present on ECG, but then disappears for 1 or more beats, before resuming.
What is a fusion beat?
Produced when the ventricle is simultaneously activated by both the paved and Supraventricular (native) impulses.
ECG WILL SHOW:
shortened pacemaker spike and narrowed QRS duration narrowed as normal impulse is occurring at the same time as pacemaker fires.
Pacemaker syndrome ?
Occurrence of symptoms relating to the loss of AV synchrony in patients with a pacemaker.
This means that the atria contract at the same time, or after ventricular contractions ~ causing reduced cardiac output.
Can result in Cardiogenic Shock and Heart failure .
These patients will require an upgrade from a single chamber to a dual chamber pacemaker
What is an ICD?
Implantable Cardioverter Defibrillators (ICD’s):
Monitors heart rhythm and it appropriate arrhythmia is detected, then a shock would be administered.
Appropriate discordance ?
Identical to BBB - expect to see ST segment elevation/depression and T wave in the opposite direction to QRS COMPLEX VECTOR:
E.g; if QRS is negative (depression) , T wave should be positive , and vice Versa.
How to treat Pacemaker problems?
1) (C) ABCDE
2) 02 therapy if SP02 < 94%
3) Atropine if indicated (bradycardia)
4) restrictive approach to fluid therapy. Only administer if there is evidence of HYPOperfusion.
