CIEDs Flashcards
CT and MRI can both interfere with ICD function
true
CTs can cause oversensing
MRIs not sufficient evidence. Manufacturers may list conditional circumstances when to perform. Most centers will not do MRI
imaging can help identify the device when it is not known
true
Indications for CIED
bradycardia Sinus node disease long QT HCM Dilated cardiomyopathy - 3chambers (RA and both ventricles)
Subcutaneous ICD
larger than transvenous models
no antitachy functions or sustained antibrady functions
higher defib threshold
CIEDs respond to low-amplitude electrical signals nd can be altered by extraneous signals such as:
electrocautery RFI ablation MRIs Radiation therapy lithotripsy
Unipolar leads
more easily effected since the + and - ends are further from each other
Bipolar leads
most modern PM
better shielding of lead ends reduces risk of interference
PM code
1st letter
denotes cardiac chamber being paced
Atrium
Ventricle
Dual
PM code
2nd letter
cardia chamber for electrical activity being sensed A V D 0 - none
PM code
3rd letter
Response to sensed signal 0-none I - inhibition T - triggering D - dual inhibition and triggering
PM code
4th letter
Rate response features
PM code
5th letter
denotes chambers in which multisite pacing is delivered
Most common PM settings
AAI
VVI
DDD
Ansynchronous pacing
simplest form Modes are: AOO VOO DOO meaning aria are paced with no sensing and no response since there is no sensing)
It can compete with pt’s intrinsic rate and depletes the battery life faster
Single chamber pacing
can be atrial or ventricular
A-pacing requires the AV node and bundle of HIS to be intact (AAI).
Those with AV node disease can have a single chamber ventricular pm (VVI). senses the R wave, and if present, the PM discharge in inhibited
PM syndrome
can occur with VVI from loss of AV synchrony
symptoms are syncope, PNS, orthopnea, hypotension, pulmonary edema
changing settings to DDD can relieve this
DDD
more common methods when the SA or AV node is diseased
physologica pacing since it retains AV synchrony
there is a lead in the RA and one in the RV
If the atria is sensed, then the atrial pacer is nin habited
If the ventricle is sensed, the nteh ventricles is inhibited
This mode allows the SA node ot increase rate with exercise
DDI
there is atrial and ventricular sensing but only responds t]wit inhibition
only used when there are tachy dysrhythmias
Rate adaptive PM
can be used in pts who don’t have appropriate HR responses during exercise
BB, CCB or sick sinus common causes
ICDs
include a pacing and shocking function to manage brady or tachy arrhythmias
Senses the R-R interval
-short intervals interpreted as tachy
RV lead to sense ventricular depolarization -
if Vfib sensed, a second waveform analysis occurs
-10 to 15 sec delay
-pt may lose conciousness
ICD modes
1st letter
chamber shocked O-none A V D
ICD modes
2nd letter
Anti-tachy pacing chamber O A V D
ICD modes
3rd letter
Tachycardia detection mechanism
E - electrogram
H - hemodynamic
ICD modes
4th letter
Anti-bradycardia pacing chamber O A V D
CRT
used for CHF pts caused from asynchrony and conduction blocks
Using 3 pacing leads in the RA, RV, coronary sinus, the device can be programmed to resynchronize the heart
indications are EF <35%, QRS prolongation, NYHA 3 or 4
ICDS/surgery
Timely interrogation pre-operatively (ASA recommends 3 months prior, others say 12 months)
Re-programming preferred vs magnet
Pad placed so current heads away from device
bi-polar cautery
current 5 cm from pacer leads
Post-op interrogation
*anti-tachycardic functions and rate response functions are usually suspended just before surgery if any EMI is possible
Pacer insertion
under conscious sedation or MAC
routine monitoring
pt supine with head turned away from operative side
anti-arrhythmic drugs available
complications from pacer insertion
pnemo/hemo thorax
air embolism
*tension pneumo suspected if pt suddenly deteriorates in PEA
cannulation of subclavian artery
Factors that can increase depolarization threshold of PM
hyperkalemia acidosis antidysrhythmic meds hypoxia hypoglycemia local anesthetics MI hypothermia
Factors that can decrease depolarization threshold of PM
hypokalemia increased catecholamine levels sympathomimetic drugs anticholinergics glucocorticoids stress/anxiety hyperthyroidism hypermetabolic state
Magnets and surgery
Magnet response is not standardized
not intended to treat PM emergencies or prevent EMI effects
incorporated to allow for assessment of battery life and pacing threshold
Placing a magnet over a generator may produce no change at all bc not al PM switch to asynchronous mode. Some may only go into asynchronous temporarily
Those that do - have HR btwn 85-100
Some will have loss of pacing or transition into continuous pacing
Need to know what happens when you put a magnet on the device
Pts with CIED will have one of the following:
sustained or intermittent brady or tachy arrhythmia
heart failure
Asynchronous mode is used why?
to prevent inappropriate oversensing
Harmonic scalpels
US
used w/o concern for EMI
Temporary PM
common after cardiac surgery
Transvenous pacing is the most reliable temporary PM means
PACs sometimes have a pacing function
Transcutaneous is quickest emergent pacing modality -
transcutaneous pacing
V3 and posteriorly at inferior scapula. Captures the RV then activates the LV.
Maintained at 5-10 mA above capture threshold as tolerated
