General Knowledge Flashcards
Stages of HF diagnosis after ECHO
EF
LV or Atria- ?dilated
Hypertrophic
Hypokinesis
Valves
RV
HF - BB
Dilate vessels, reduce O2 consumption and workload
Carvedilol
Bisoprolol
HF - ACE
Rampiril
Lizinopril
Inatopril
HF - ARBs
Candesartan
Losartan
Alsartan
Propafenone
Lower HR
For symptomatic SVT without structural disease
In what arrhythmias can Flecainide be used? What are its effects?
Cardio version of AF without structural disease
AVNRT, AVRT, PAF
Persistent VT or frequent PVCs with symptoms
Reduces conduction throughout the whole heart
Flecainde and propafenone ECG effects
QRS and QT prolongation
Amiodarone
Most potent drug
For Serious VT/SVT = WPW, flutter, AF to sinus rhythm
Deceases automaticity
Amiodarone effect on ECG
Prolongs QT
Sotalol
For VT/SVTs, rhythm control in SVTs after return to sinus rhythm
Decreases automaticity
Sotalol effect on ECG
Prolong QT
BB
Reduces catechlomines
Reduced inotropic (contractility) = reduced O2 consumtion
Reduced chronotropy (HR) = prolonged diastole thus increased myocardial perfusion
Decreased automaticity = decreased sinus rate
BB on ECG
Prolonged AV interval
QT shortens
ChadVASC score components
Age: <65 (0 points), 65–74 (1 point), ≥75 (2 points)
Gender: male (0 points), female (1 point)
Congestive heart failure (1 point)
Hypertension (1 point)
Stroke, transient ischaemic attack (TIA) or thromboembolism (2 points)
Vascular disease (1 point)
Diabetes mellitus (1 point)
CHADVASC score interpretation
Scores of:
0 indicates low risk
1 indicates low-to-medium risk
2 or more indicates moderate-to-high risk
Split cathodal pacing causes
Increase in stimulation threshold and decrease in impedance
Common inappropriate causes of MS
FFRWOS
Atrial lead sensing v signals
Structures not surrounding the ostium of the CS
Crusts terminalis
PMT algorithm occurs during Sinus tachycardia why?
Because increase in atrial rate means p waves fall into PVARP
Increasing MTR resolves this
S2 is
First premature stimulus
Smaller electrodes cause
Increased lead impedance
Systolic BP is equivalent to
After load
Dispensibility or pressure x volume means
Compliance
Isovolumetric contraction is
Time from mitral valve closure to Ao valve opening
By what % does stroke volume increase during exercise
50%
DBS (drawn brazed) involves what metals
A combination of silver + nickel alloy conductor materiel
However a small pacing cathode allows for what?
Improved stimulation threshold
What procedures should be performed in highly symptomatic PAF
Cath and TOE
What drug reduces morbidity in MI
BB
AVB + VT/VF is seen in what neuromuscular disease
Chages disease
Normal INR ranges
2-3
What drug classes cause risk if torsades?
1A, 1C and III
erythromycin, azythromycin and tricyclic antidepressants
Types of ATP/BF termination
Type 1 - VF/successful 1 ATP to sinus rhythm
Type 2 - VF/unsuccessful 1st ATP with eventual spontaneous termination
Treatment of malignant vasovagal syncope
Metroprolol
BB
Long QT is related to what neuromuscular diseases
Anderson, Romano-Wad, Jerville syndromes
Normal HV intervals are
35 - 50ms
Thyroxitoxics manifests as
Polymorphic VT
What drug does not trigger torsades?
Adenosine
RV dysplasia vs brugada
RV dysplasia = MVT
Brugada = PVT
Most common cause of failure to output is
Oversensing
After acute MI should pacing be performed or not
Temporary pacing due to risk of CHB
Diastolic dysfunction
Impaired early diastolic relaxation due to ischemia = increased stiffness and LV hypertrophy
Left sided symptoms
Dyspnea on exertion
Tachycardia
Cough
Right sided symptoms
Nausea
Bloating
Swelling
True or functional loss of sensing caused by
Pseudofusion, URB, oversensing resulting in undersensing
True or functional loss of capture is caused by
Isoelectric depolarisation, undersensing intrinsic beats, lead dislodgement
What causes longer AA or VA intervals
Make/break conductor fracture. FF sensing, PMT algorithm
Failure to pace is caused by
Battery failure, after potential oversensing, unipolar to functional bipolar
Why does atrial undersensing cause inappropriate ICD discharge?
Caused by more V than A = classification as VT causing detection
AV desynchronisation/RNRVAS involves
Retrograde conduction, functional non sensing and functional non capture
RV on EGM and LV on AGM shows what?
Determines the amount of separation between the LV and RV leads
Class I removal indications for infection
Endocarditis
Sepsis
Pocket abscess
Skin adherence
Occult gram post Bacteremia
Class I lead removal indications for thrombus & stenosis
Thrombus on lead
SVC or subclavian occlusion
Stent deployed in vein with lead
Class I indications for removal of functional or non-functional
Life threatening arrhythmias caused by leads
Immediate threat of leads left in place
Leads interfere with other leads
How does insulation break causes LOC
Current drain from lead means 2x as much current is required to capture the same tissue
Equation for capacitor energy
E = 1/2C x V2
Most common cause of safety pacing
VEs
Define threshold slope
Amount of energy required to initiate or trigger sensor activity
Define sensor slope
Level of response of the device to sensor signals
Sleep apnea programmable solution
Rate drop response
Sudden Brady response
Treatment of AF
Diltiazem in AF = effective rate control
Contraindication for MRI in non MRI CIEDs
Having an abandoned lead
Lead fracture
Epicardial
What depletes battery most quickly
Increased current drain
2:1 HB seen in during recovery following surgery. What is the next step?
Implant permanent pacemaker
Determine the Transvenous ICD shock vectors
B - tip
A - can
X - SVC or azygous cool
Identity common analgesic DRUGS
Codeine.
Fentanyl.
Hydrocodone.
Meperidine.
Methadone.
Naloxone or naltrexone.
Oxycodone.
Reversal drugs for benzodiazepines and opiates
Opiates - Naxalone
Benzodiazepines - flumazenil
Epicardial pacing is recommended for:
Patients <15kg
- Patients with intracardiac shunt lesions
- Limited access to atrium or ventricles (e.g. patients with single ventricular physiology post fontan palliation)
- Prosthetic tricuspid valves
Disadvantages of epicardial pacing
Disadvantages
Associated with higher chronic stimulation thresholds, higher lead failures and fractures, early depletion of battery life.
Advantages of epicardial pacing
Preserves venous access for future use
Steriod eluting epicardial leads are preferred as they prevent threshold increase in the long term.
LV apical pacing is the best site for epicardial leads in children
Which pouch is not know for reduced infection rates?
Parsonnet
What parameter you change for this patient
Sensitivity - sensed AV delay should be 90ms. The Vp occurs much shorter than that thus it can be assumed that A undersensing has occurred which did not start and AVI so Vp after LRL times out occurs
Factors that can cause high thresholds, small p or R waves and higher lead impedances (and sometime LOC)
Macro dislodgement
Micro dislodgement
Lead fibrosis
Lead insulation or conductor failure
What can be seen in this EGM trace?
AVNRT
AVRT has a longer VA interval
In a patient with a HIS bundle > 100ms what would be the next suitable approach
Implant pacemaker - class IIa indication
For symptomatic SVT
Ep study should be performed
Which of the following is the most common clinically relevant interaction with an MRO and a non-MRI conditional device?
Power reset
AHA guidelines for AF treatment
1st line - Beta blockers
flecainide, propafenone, and sotalol
Alternatives: Amiodarone and dofetilide
- A 67yo male with Class II HF, EF 32% and QRS 140ms is implanted with a CRT-D. Remote FU detects some bouts of PAF at the 9 month period. The patient is then seen in clinic and diagnostics indicate the AF burden is 8%. He is asymptomatic. Which is the most appropriate for this patient?
a) Continue to monitor the patient before intervention
b) Start on aspirin
c) Start on sotalol
d) Start on dabigatran or rivaroxaban and consider turning on atrial overdrive pacing algorithm
d) Start on dabigatran or rivaroxaban and consider turning on atrial overdrive pacing algorithm
Subclavian crush affects impedance how?
Higher impedance
upper limit of vulnerability
The weakest or above which VF will NOT induce
Evoked response
Electrical event (from depolarisation) caused by output pulse
Algorithms for trouble shooting lead noise that diagnose lead noises caused by a) fracture of the pacing or sensing conductors, b) an insulator rupture, or c) an insufficient tightening or a faulty insertion of the lead connector in its receptacle also for over-sensing of P and T waves, double counting of the R wave = elimination of inappropriate therapies
Noise revision
Post sense delay decay
How does noise discrimination work?
discordance between the 2 channels be detected, presence of short cycles on the bipolar channel (near field) but not on absence of discrimination channel ( far field)
True v arrhythmia = both channels are concordant - short cycles are detected on the bipolar channel and discrimination channel
When can post pacing v blanking be changed
During the over sensing of post pacing T waves
Determine patient Vs device related causes of PMT
Patient-related causes include PVCs, PACs, the accessory pathway, and an interatrial conduction de- lay.
Device-related causes include unusually short programmed PVARP, long programmed AV interval, atrial undersensing, and atrial failure to capture.
Effect of epicardial temporary pacing post surgery that may or may not be working
Additional pacemaker artifacts
Competition between permanent pacing and temporary pacing
Inhibitor if permanent pacemaker by temporary pacing
Define amylodosis
serious conditions caused by a build-up of an abnormal protein called amyloid in organs and tissues throughout the body
Explain atrial preference pacing
increasing the atrial pacing rate = suppression of a spontaneous atrial rhythm and prevent supraventricular tachyarrhythmias.
APP responds to changes in the atrial rate by accelerating the pacing rate until it reaches a steady paced rhythm that is slightly faster than the intrinsic rate
Define fallback mode
designed to limit tracking of atrial arrhythmias by automatically mode switching to a non-tracking mode when programmed ATR criteria are met
Steps to troubleshooting oversensing on an ICD lead
Adjust blanking or refractory periods e.g. p wave oversensing adjust PAVB
Reduce sensitivity
Replace lead
Differential diagnosis for this trace includes
RV lead dislodgement to tricuspid annulus or right atrium near valve
RV lead implant in CS
Lead to lead interaction with A lead hitting V lead during valve motion
RV distal coil crossing tricuspid valve this sensing atrial activity im inter grated bipolar
RV insulation break near A lead = atrial sensing
What is occurring in the EGM below?
FFRWOS
Although the EGM pattern shows an RNRVAS pattern with SIR (RR) activated after MS the atrial signals continue with double counting pattern suggesting some oversensing
Suggested programming parameters for PAF
DDIR 65 base rate/ 175ms AVI/ 65bpm atrial tracking limit/ 110 sensor rate limit
Identify the first and second most common causes of PMT
- PVC
- Loss of atrial capture
altered AV synchrony = allows retrograde conduction
Applying a magnet during a PMT shows what?
Differential diagnosis of PMT is atrial tachycardia or sinus tachycardia
If Application of a magnet during the taxhyarrhythmia fails to terminate the tachycardia = not PMT
When is pseudo pseudo fusion most commonly seen?
DVI mode
Committed atrial capture
Defined as when an stimulus artefact from one chamber is superimposed on a deflection arising from another chamber
What is the clinical relevance of finding fusion or pseudo fusion
Clear fusion confirms capture
pseudo fusion or questionable fusion:
- failure to sense intrinsic
- failed capture (increase pacing rate to assess morphology)
What does this ECG of a DDD device show?
RR intervals occur at 80bpm but pacing spikes occur at 60bpm regardless of intrinsic = intermittent undersensing
Intrinsic QRS sensed
VA interval occurs and times out
Ap delivered and PAVB starts
Intrinsic QRS is blanked and Vp is delivered on T wave
Ap and Vs occurring at the same time = pseudo pseudo fusion
In this AAI pacemaker programmed at 60bpm what is occurring in the EGM
Atrial undersensing and non capture due to lead dislodgement
Think it’s not sensing anything; hint pseudo fusion occurs
Do spike cause depolarisation?
Why is atrial undersensing in ICDs dangerous?
Atrial undersensing causes V > A = counters towards detection
What is the detection criteria for treatment of atrial tachyarrhyrthmias?
To meet criteria for atrial tachyarrhythmia -> A > V (more A than V)
In AAI no V lead so no V sensing to compare atrial events with = detection never met
What occurs with battery nearing ERI?
Sudden rate drop (magnet rate)
change to simpler mode
Sudden increase of pacing outputs
Causes of T wave oversensing include?
Based on near field EGM:
Small sensed R wave to T wave ratio (decay delay curves depend on the size of the R wave = difficult to reprogram with small R wave -> lead revision)
R wave larger than T wave amplitude
During Vp (pacing rate may be slowed = bradycardia not inappropriate shocks)
Reprogrammable Trouble shooting options for T wave oversensing caused by small R wave
- Lead revision
- Reduce sensitivity
- Adjust delay decay
Ventricular lead oversensing signals from the atrial channel suggests what?
Lead dislodgement
Reasons for paced rates below LRL include?
Oversensing = underpacing
Open circuit
Battery depletion
Auto capture algorithms
PVARP extension for PVCs
Rest/sleep mode
Hysteresis
What is one hint that auto capture threshold tests are occurring?
They occur with back up safety pulses when capture fails
What is happening in this trace?
Pacing artefact at beginning of QRS, then pacing spike in T wave = Ap causes ventricular depolarisation with AVI timing out and Vp being delivered on T wave.
What can cause failure to output?
Header connector pins not in fully
Can failure
Magnet mode can be used to rule out failure to output I.e. no pacing artefact and intrinsic morphology
Define competitive atrial pacing
Triggering atrial arrhythmia by Ap on atriums vulnerable period
Can the LRL be violated in V based or A based timing
Violated in V based timing
Not violated in A based timing (Vs in VAI)
A based timing is the main timing cycle used within Hybrid based timing. When is V based timing with hybrid timing?
When loss of AV synchrony occurs it switches to V based timing (Vp)
Pacing above LRL
RR
MS
Sudden rate drop response
Magnet mode
V auto capture
Pacing below LRL
Hysteresis
Sleep or rest rate
Atrial based timing
AVI longer than programmed
AV hysteresis
Algorithms for intrinsic conduction
URB
The atrial escape interval is violated during what timing cycles?
Impossible to violate during A based timing
Can be violated during V based timing
Things to improve CRT response
Increase LRL
Enable ventricular sense response
Aggressive medical therapy
AF ablation
AVN ablation
Define virtual electrode
regions of cardiac tissue for which the membrane. potential is electrotonically altered by the stimulus current.
Define anodal stimulation
Anodal stimulation - capture at the pacing anode instead of cathode.
more common at higher pacing outputs. If anodal stimulation occurs when a CRT device is programmed LV tip to RV coil, the RV is unintentionally captured instead of the LV.
How can pectoral myopotentials cause inappropriate detection?
By distorting Far field EGM during SVT leading to morphology mismatch e.g. sinus tachycardia during exercise
Explain v based timing in relation to rate
If there is intact AV conduction; after an Ap, the AR interval would be shorter than the programmed AVI = slightly faster paced rate
Explain the different between V based timing and A based timing in relations to rate
V based timing - AVI interrupted with instrinsic beat = short AVI than programmed -> slightly faster paced rate (intrinsic earlier = VA timer starts earlier
So next AP occurs at a slightly faster rate)
A based timing - AVI interrupted with intrinsic beat does not alter AA timing = rate stays at LRL I.e. AAI (because it’s AA timer rather than VA that is reset)
Explain modified atrial based timing
Vp = VAI from V to next V event (V based timing)
If intrinsic occurs and interrupts the AVI, it switches to A based timing to ensure accurate pacing rates during intrinsic conduction
Define fall back response
During mode switch for AT
Rather than V rate falling abruptly to LRL from the high rates before MS, it allows gradual fall back to LRL to minimise symptoms
Define rate smoothing
Introduces pacing impulse earlier than expected to minimise cycle length variation following PVC
RID + Vs RID- markers
RID +.- rhythm ID morphology match
RID - - rhythm ID morphology mismatch
Troubleshooting options for air in header
Entrapped air usually disappears after 1-2 days but trouble shooting can be:
Programme to DOO with therapies off and observe for 24hrs
What noise source does the EGM below display?
Noise due to loose set screw
Occurred during provocative manoeuvres
Potential causes of R wave diminution
Acute - Lead dislodgement, perforation, loose set screw
Chronic - lead maturation/fibrosis, structural lead defect
In what setting does electrical power rest occur
High voltage or magnetic fields
Expect to see continuous electrical signals on ff and nf and ask exposure history (figure out what the patient was doing at that time)
Severe reset = therapies turned off
Frequent arrhythmia in the immediate period following lead placement can result from what?
Cardiac perforation
Mechanical ectopy from the lead
Inappropriate programme of the device
Presence of endocardia or epicardial leads
Identify one characteristic about DVI mode
Atrial stimuli May occur following the onset of ventricular depolarisation
Addition of an SVC coil to an ICD lead will do what to an ICD waveform using a fixed tilt
Shorten the waveform
Adding more metal creates a parallel circuit this reduces the total amount of resistance
This if same voltage and tilt was applied to single Vs dual coil system due to less resistance the % tilt is reached at a much quicker rate.
Define HV interval
The HV interval represents conduction time from the proximal His bundle to the ventricular myocardium
Normal 40-60ms which means after Vp activation should only take 40ms
Define AH interval
AH interval represents conduction time from the low-right atrium at the interatrial septum through the AV node to the His bundle.
What is occurring in the EGM below and identify it’s trouble shooting
P wave oversensing from the ventricular lead during His bundle pacing
This is because the His lead is commonly located in the atrium when pacing = small R waves and p wave over sensing
Increase PAVB, change lead polarity or decrease V sensitivity
What is occurring in the EGM below?
His potential oversensing
Adjust sensitivity or sensing polarity for better ratio between P and R waves
What to consider to overcome BB delay
Increase output
Move His bundle lead distally
Virtual electrode polarisation
Selective HBP
Pure HB pacing -> stimulus to Vp is = intrinsic HV interval so paced QRS is the same as intrinsic QRS = BBB normalisation
Vp ventricular activation overrides purkinje system
Assume catheter is within the HBP
QRS narrows at higher outputs due to fusion between RV and HBP
Nom selective HBP
Capture of both local myocardium and conductive tissue = Stim - V interval < HV interval
At Lower pacing output changes are seen in QRS due to loss of HB capture
QRS widens during lower outputs due to loss of HBP capture
Shorter AVI than programmed
NCAP
V safety pacing
MVP
dynamic AV
Negative AV
Auto thresholds
define and explain LV protection period
Left ventricular protection period
Prevents LVp in LV vulnerable period After LVs I.e. when LV PVC occurs
Define load and how it relates to the circuit of a device
Impedance applied to a circuit
Small load = small resistance I.E. constant current
Large load = large resistance I.e. constant voltage
Identify signals that the VRP is meant to blank
T wave
Paced QRS
Own impulse
Excessive afterpotential
Why is Vsp stimulus delivered in a shorter time than normal physiologic AV delay
Pace within refractory period = no pace in vulnerable period
What is the effect of programming a PVARP shorter than the VRP
Increased FFRWOS of the end portion of Vp QRS
Programmable parameters that can be changed to test for PMT
Low A output
Short PVARP
Highest A sensitivity
Arrhythmia termination with Vs suggests what?
SVT
Safety pacing can result from…?
Normal AV conduction with atrial undersensing
Pacing a patient after tricuspid annuloplasty allows for which type of pacemaker?
Endocardia lead can be placed across the tricuspid valve
What is the next step if unable to extract lead via simple traction r active fixation mechanism?
Cap the lead and leave it in situ
Incremental options for extraction of helix does not extract during lead extraction
Stylet down other leads for stability
Active fixation mechanism and traction
Lead rotated and manual traction
Locking stylet to aid traction
mechanical sheaths or laser sheaths (passes over the lead, surrounding it and freeing it from the body by disrupting scar tissue as it is advanced toward the heart)
Snare
Cap and leave in situ
rate of major complications was 1.6% to 2.0% - tearing the surrounding blood vessel or perforating = bleeding around the heart
Feature of activity sensor pacemaker (pressure)
Less responsive to ascending than descending stairs
Most common clinical problem with AAI pacing is
Atrial undersensing
Crosstalk does not occur in what mode
Committed DVI
What has an effect of interrupting atrial flutter?
Rapid atrial pacing
Explain why acute MI with bilateral BBB and no AVB would receive temporary pacing
MI = ischemia of conduction system fascicles -> BBB or AVB thus risk of progression to AVB is high
Temporary pacing provides hemodynamic support following acute MI = cardiovascular management prior to myocardial necrosis
In AF with fast Ventricular conduction, what would be the usefulness of a short refractory period?
A short refractory period would account for rapidly conduction ventricular contraction (all As so no pacing)
High impedance/resistance lead =
Low current drain and long battery longevity
What is the disadvantage of VA conduction
Loss of atrial kick = decrease stroke volume -> CO
increase in atrial pressure causing acute atrial stretch and reverse flow = AF
Atrial contraction against close AV valves
If sensor indicated rate is higher than upper tracking rate what would you expect to happen
AV sequential pacing - ApVp
A rate faster than upper sensor would lead to URB
Sotalol causes bradycardia in the context of PAF with bifascicular block and VF with symptoms of syncope. What should be done next?
Discontinue Sotalol and implant PPM
Pacemaker indication in the context of CHB in Bifascicular block
Sotalol can cause pause dependant prolongation if QT = vt
Syncope caused by sotalol
Any patient with proarrhythmia due to anti arrhythmic should be discontinued
No ICD in AF
RV apical pacing would show what axis on the inferior leads
Negative in inferior leads
RVOT pacing would show what axis in the inferior leads
Positive
1 or more SCD risk factors for HCM is what class indication?
IIa
What RVOTO gradient in HCM suggests immediate risk of SCD dispute RVOT being a low predictor
> 30mmHg
What indications suggest implant one bibentricular ICD
Low EF
What is the mechanism behind programming high pacing rates following AVN ablation for the first 3 months post procedure?
Rapid change in HR from AF to slow Brady pacing can allow Brady induced VT (torsades).
What is the effect of Vp on mitral regurgitation
Increase MR
Why is dual chamber pacing important during sinus pauses such as that occurring in malignant syncope?
Maintain AV synchrony during long pauses
Identify examples of benzos
Diazepam
Clonazepam
Lorazepam
Alprazolam
Anything with am
Identify examples of opiates
Tramadol.
Methadone.
Pethidine.
Oxycodone.
Fentanyl
These signs suggest?
- low BP
- tachycardia
- distended JVP
Pericardial tamponade
Poor bilateral breath sounds and no extra thoracic venous access site suggests?
Pneumothorax
Dissection if the superior vena cava would present as?
Low BP
Tachycardia
JVD distension
Swelling of head and upper extremity veins
Magnet application in CRTs inappropriate because…?
Stops biventricular pacing efficiently and could cause hemodynamic compromise as a result
An application of a magnet in an ICD does what?
Deactivated detection and therapies
No asynchronous pacing
Radiation on device means
Change device
Tachycardia that persists despite intermittent lack of conduction to ventricle
AT
Conductor failure causes
Oversensing
Increased impedance
Increased Pacing threshold
Failure to defibrillate due to current shunting
Failure to generate energy for shock is caused by
Failure of pulse generator
Short circuit
Insulation failure close to can will cause
Current arching leading to direct damage to can with transistor short and ICD system failure
Failure to plug SVC port results in..?
Failure to deliver shock
Reversal of leads in ICD header results in…
Reversal of shock polarity and unipolar sensing
Troubleshooting for failed shocks includes
Reprogramming shock wave
Reposition lead
Add azygous/array lead
Highest risk of hemotoma
Heparin
20% risk/ 5x the normal
AF that is not detected, AF with fast ventricular conduction leading to pacing what is the troubleshooting mechanism
Shorten PVARP
Explain Blanked flutter search
Blanked flutter search – Monitors for A–A intervals for 2:1 blanking of atrial events.
2:1 blanking detected = extends PVARP and the VA interval to uncover blanked AS events
If an A-A interval shorter than the detect rate interval is detected, 2:1 sensing of an atrial tachyarrhythmia is assumed. Otherwise, the pacemaker resumes monitoring for 2:1 sensing of atrial tachyarrhythmias in 90 seconds.
Voltage stored on a capacitor is equal to what?
Initial shock voltage
Cathodal shocks cause what wavefronts?
Anodal wave fronts that are expanding and proarrhythmic
Cathodal wavefronts are collapsing and self terminating
Trouble shooting for Excessive safety pacing from VEs.
Shorter blanking period
Define rate smoothing
Used to minimise variations in RR intervals/ regularise v rhythm
Atrial overdrive pacing just above the pacing rate
Ventricular rate stabilisation runs off PVCs
Post pacing interval
Time required for last stim to reach circuit, travel around and return to pacing cite
3 things that affect the ability of a device to sense an evoked response
Polarisation effect
Electrode- lead interface
Tip to ring space
What is RV latency dependant on?
Rate and output
Why is HIS bundle pacing inferior to conventional pacing
Long implant time
Higher risk of lead dislodgement
Steep learning curve
High thresholds
Not applicable to patients with BBB
How does tissue fibrosis affect leads
Improves stability
Increases lead size thus increases current drain
Equations related to power
P = I x V
E = P x T
All together is E = I x V x T
Frequency to BPM calculation
1 hertz = 60 Bpm
Generator erosion is considered as…
Indolent infection
Extract
Troubleshooting for phrenic nerve stimulation
Lower outputs
Change electrode configuration
Reposition lead
Factors not associated with lead extraction complications
High BMI
Prior open heart surgery
Open loop
Accelerometer
Piezoelectric
Partial open loop
Temperature
Respiratory rate
Closed looo
CLS
Minute ventilation
Source impedance
Voltage drop from IEGM origin to proximal lead
Extended bipolar (lV tip to anode (ring or coil) results in…?
Anodal capture
Diaphragmatic myopotentials (on V channel)
Pectoral myopotentials are in unipolar configuration
VT/VF zone happenings
Detection met
Charge starts
Re-confirmation (short cycles that fall into VT/VF zone e.g. 2/5) - occurs during charging because aborted charges = prolonged battery life.
Charge end
Shock delivery
Determine characteristic of non-committed shock
First shocks are always non-commuted in ICDs
Shock not delivered at end of capacitor charge
