Temporary cardiac pacing Flashcards
(26 cards)
What are the 3 techniques of temporary cardiac pacing?
- transvenous
- transesophageal
- transcutaneous
What are pros and cons of transcutaenous pacing?
pros:
* quick –> emergeny procedure
* patch electrodes can also be used for cardioversion/defibrillation
* non-invasive
cons:
* painful + stressful –> deep sedation or GA required
* only short-term
What are pros and cons of transesophageal pacing?
pros:
* quicker than transvenous
cons:
* deep sedation or GA required
* only short-term
* paces only atria –> does not work in AV dysfunction
What are pros and cons of transvenous pacing?
pros:
* long-term
* placement under sedation possible
* improved patient comfort (can be awake after insertion)
* lower cost
* relatively easy
* more consistent capture in patients with SN and AV dysfunction
cons:
* takes longer –> no emergency procedure
Describe the technique of inserting a transvenous pacemaker.
a lead wire is inserted via a sheath introducer into either jugular, femoral or lateral saphenous vein via Seldinger technique –> flush with heparizined saline –> bipolar pacing lead wire (either semirigid leat wire or associated with a balloon-tipped catheter) advanced into the RV apex until ventricular capture –> pacing lead connected to external temporary pacemaker –> current is generated from a temporary pulse generator that is external to the body
Name 6 complications of transvenous pacing
- lead dislodgement + loss of capture (!)
- thrombosis
- bleeding
- infection
- ventricular arrhythmias
- cardiac perforation
What are pros and cons of placing a transvernous pacemaker prior placement of a permanent pacemaker?
Pros:
1. rapid rescue if asystole
2. improved CO and BP with low ventricular escape rates (<30min) or errativ ventricular escape rhythm
Cons:
* sedation required
* increased surgical time
* lack of evidence for clear improvement in outcome
What are the 4 main indications for temporary cardiac pacing?
- HR + BP support while patients are under GA during permament pacemaker (most common) –> transvenous
- HR + BP support in dogs with clinically silent nodal dysfunction that experienced profound and medically refractory bradycardia while undergoing GA –> any
- Medically refractory bradycardia that needs permanent pacemaker placement, but can’t be done at the moment due to contraindications (e.g. systemic disease, infection, endocarditis) –> transvenous
- Medically refractory and potentially reversible bradycardia, often caused by drug overdose –> transvenous
- Cardiac arrest from medically refractory sinus arrest leading to asystole in which meaningful recovery is possible –> transcutaneous
What drug overdoses can cause temporary medically refractory bradycardia?
- digoxin
- diltiazem
- verapamil
- b-blockers
What HR is usually set for temporary pacing in dogs? What energy output should be set and how can you determine the optimal energy output?
60-100/min
3mA
Start with 3mA (ventricle should be captures with every pacing impulse) –> gradually turn down the pacing threshold until capture is lost –> set to at least 2x treshhold value
If permanent pacing is planned, what should be thougt of when placing the temporary transvenous pacing system?
Don’t place it into the vein that shall later be used for the permanent pacemaker.
What is required for a transcutaneous pacing system?
- pulse generator
- good-quality ECG tracing (dog’s foodpads)
- disposable transthoracic patch electrodes on right + left hemithorac (fur clipped + ECG paste) over prevordial impulse
- +/- elastic nonadhesive bandage
How do you set up the transcutaneous pacing system?
- optimize lead selection + ECG gain for accurate sensing of the patient’s intrinsic cardiac rhythm
- chose desired pacing rate
- increase pacing current gradually until ventricular capture
- confirm capture by palpation or audible Doppler blood pressure
- maintain current output just above capture threshold (30-160mA in one study)
What equipment is required for a transesophageal caing system?
- transesophageal pulse generator
- bipolar pacing catheter or quadripolar electrophysiologic catheter
- semi-rigid plastic guide (optional)
What is the benefit of a quadripolar electrophysiologic catheter over a bipolar pacing catheter?
- lower pacing tresholds
- more consistent pacing
Describe the placement of a transesophageal pacing system.
- patient under GA in lateral recumbency
- insertion of pacing catheter transorally
- advance to the level of the diaphragm until pacing of diaphram
- withdraw cahteter slowly until atrial pacing
What mode is the pacing stimulus of the transesophageal pacing system usually delivered in?
AAI
A = paces atria
A= senses atrial activity
I = inhibits pacemaker output when intrinsic artrial activity is sensed
What pacing amplitude and pulse width are usually needed to ensure capture of the atria, but also minimize extraneous muscle stimulation?
pulse width: 2-10ms
pacing amplitude: 7-30mA
Start with 20-30mA and then gradually reduce until loss of capture to find threshold
What does the pacing treshold depend on in transesophageal pacing?
- recumbency
- relationship between esophagus and heart
- breed confirmation
- catheter shape
- polar surface area
What are common problems with a transvenous pacing system and how are these troubleshooted?
- does not advance across tricuspid valve –> balloon-tipped pacing catheter or molding 3-4cm of tip of wire into a 20-30° angle
- inability to capture due to poor contact of the wire –> check position with fluoroscopy, sedation (if moving loads), adhering the pacing wire to the sheath introducer, increasing the current
- No pacing spikes seen –> due to failure of battery, pulse generator or loose connection –> change battery
What are common problems with a transcutaneous pacing system and how are these troubleshooted?
- inconsistent pacing success rates –>
* suboptimal electrode placement: over cardiac impulse (if too ventral then current does not cross heart but goes over sternum)
* suboptimal ECG recordings
–>increase pacing amplitude, generous gel application, nonadhesive bandage wrapping around chest - over- and undersensing of the intrinsic cardiac rhythm –> set pacer to non-demand mode at HR > patient’s intrinsic rate –> higher HR will supress underlying rhythm –> more consistent pacing
What ist a common problems with a transesophageal pacing system and how is it troubleshooted?
inconsistent pacing –> change position, check with fluoroscopy for optimal relationship of esophagus + heart
What is the most common complication of transvenous pacing?
Lead dislodgement
Name 5 common complications reported with permanent transvenous pacing?
- hemorrhage
- infection
- ventricular arrhythmias
- cardiac chamber perforation
- thrombosis
