Part II Cardiac Devices Flashcards
Asynchronous pacing modes
AOO
VOO
DOO
Single chamber atrial pacing modes
AAI
AAT
Single chamber ventricular pacing modes
VVI
VVT
Dual chmaber AV Sequential
DDD
DVI
DDI
VDD
What is pacemaker syndrome
result of deleterious hemodynamics of ventricular pacing
symptoms of pacemaker syndrome
hypotension, syncope, vertigo, fatigue, exercise intolerance, weakness, dyspnea, CHF, pts are aware of beat to beat variations in co
Pathophysiological changes with pacemaker syndrome
- complex interaction of hemodynamics, neurohumeral and vascular changes induced by loss of AV synchrony
- common in pts with intact AV conduction pathways
- retrgrade VA conduction insures a constate state of AV dys-synchrony
First two weeks after intracardiac device placement a ________ _______ in pacing threshold is seen/
sharp increase
In patients with an intracardiac device, an acute increase in potassium results in
increases the resting membrane threshold to less negative and makes capture easier
In patients with an intracardiac device, an acute decrease in potassium results in
decreases the resting membrane potential to a more negative value, making capture more difficult
General considerations of intracardiac device
- k+
- myocardial infarction scar tissue
- antiarrhythmic therapy increase pracing threshold
- acid base imbalance
- hypoxia
- anesthetic drugs have little effect on pacing function.
Antiarrhythmic therapy
1a, 1b, 1c
1a (quinidine, prcainamide) 1b (lidocaine, phenytoin) and 1c (flecanide, enacainide)
Preop evaluation of the patient with a cardiac device includes
- underlying cardiac conditions
- bruits, signs of CHF, original indication for pacing or ICD placement
- routine labs (min: ECG,CXR,K+)
Evaluation of the cardiac device
- cardiac consult or device rep
- function properly?
- battery good?
- reprogram rate responsive pacemakers
- disable ALL AICDs (AHA guidleines)
- Secure alternative pacing and defibrillation routes
Effect of magnet on the pacemaker
- reed switch closes to induce non-sensing, asynchronous, fixed rate
- variability in newer models: check with manufacturer
- ECG before, during and after magnet application
Risks of magnet application
- asynchronous mode may trigger ventricular asyncrony in pts with myocardial ischemia, hypoxia and K imbalance
- New PM do not respond to magnet
- magnet could alter pacemaker programming
- device consult (except for emergencies)
Intraoperative management of cardiac device patients
- monitor electrical and mechanical function of the heart
- central lines with caution (arrhythmias and potential for dislodgement of wire if freshly placed, 2 weeks)
- defasiculate for suxxs
- avoid etomidate and ketamine
- deactivate rate responsive mode
- evaluate PM function after mechanical ventialtion
Why are skeletal myopotentials a concern for pts with cardiac devices
skeletal mypotentials from fasciculations, ect, myoclonic movements can inappropriately trigger the pacemaker or AICD
What type of electrocauter y is safer?
bipolar
Where should the ground plate for unipolar cautery be placed>
as far away from the pacer as feasible
Rules for electrocautery and PMs
- do not use within 15 cm of pacer
- pulse cautery to 1 sec bursts every 10 sex
- reprogram with magnet to asynchronous
- have alt pacing and defib available
Emergency considerations with device?
- positive chronotropic drugs available
- external defib - place paddles or patches as far away as possible from PM
- recheck program after operation
- resetting of stimulation threshold has been reported post defibrillation
Challenges with TURP or uterine hysteroscopy and cardiac devices
- Coagulation current reported to interfere with pacer function
- use magnet to asynchronous mode
Challenges with ECT and cardiac devices
myoclonic movements can trigger inappropriate dischange, use asyncronous mode
