Follow-up: Pacing system complications Flashcards
Describes generator complications encountered and respondent programming solutions. Currently weighted 4% in the CCDS exam.
Despite optimal programming, what % of patients are CRT non-responders?
30-40%
True / False
Improper connection between lead and generator may result in oversensing.
True.
A loose set screw / poorly fitted lead pin can cause make / break type connections that are registered by the device as noise, which may be sensed.
True / False
A loose set screw may result in impedance fluctuations.
True
A loose set screw can cause make / break type connections. Make = lower impedance as circuit is closed, Break = higher impedance as circuit is open.
True / False
A loose set screw may result in failure to pace.
True.
Due to oversensing of noise inhibiting pacing output.
True / False
A loose set screw may result in Loss Of Capture (LOC).
True.
Poor connections can increase capture threshold and thus result in LOC.
A QRS is observed immediately following an Atrial pace stimulus, what should one be suspicious of?
Atrial lead dislodgement into the ventricle.
If an intrinsic QRS is marked AS, with a respondent VP following in line with the programmed AVI, what should one be suspicious of?
Atrial lead dislodgement into the ventricle.
A QRS is observed following an Ap stimulus and a Vp stimulus is observed falling within the refractory period of the T-wave, what should one be suspicious of?
Lead reversal in the header.
Programming device to AAI will give rise to VVI behaviour and vice-versa.
A patient presents with wide QRS complexes (>300ms) and stimulation exit block - what should one be suspicious of?
Hyperkalemia.
Yes / No
A patient presents in clinic with exit block, they advise you they’ve recently been prescribed Flecanide. Could this be a cause?
Yes.
Flecanide increases stimulation thresholds.
How can subcutaneous emphysema elicit exit block / failure to stim in a unipolar system?
Air is a poor conductor.
Thus air surrounding the anodal active can effectively breaks the unipolar circuit and prevents correct function.
Define the subclavian crush syndrome.
Lead fracture respondent to continual pressure enacted on the lead by the first rib and clavicle.
What is a key factor that predicts subclavian crush syndrome?
A subclavian puncture that is too medial.
List 3 ways the risk of subclavian crush syndrome can be mitigated.
- Selecting a more lateral subclavian puncture site
- Using Axillary access
- Using Cephalic access
Define twiddlers syndrome.
Rotation of the device that results in twisting of the leads and a respondent increase in lead tension.
List 3 causes of twiddlers syndrome.
- Excessively large generator pocket that allows too much movement
- Obese patients with a loose generator pocket
- Patients that manipulate the generator
List 3 ways twiddlers syndrome can cause a system to fail.
- Tension on leads causes them to dislodge and retract
- Lead insulation failure
- Lead fracture
What should one always be suspicious of when diaphragmatic capture is seen at low stim outputs?
RV lead perforation.
A patient with a CRT system is experiencing intermittent ‘hiccups’. What is the likely cause?
Phrenic nerve stimulation, which gives rise to diaphragmatic contraction.
Define pacemaker runaway.
Component failure of the pacemaker, which causes extreme pacing rates not compatible with life.
Will likely initiate VF.
What is the emergency procedure for pacemaker runaway?
Cut / Remove the pacing leads from the generator.
List two ways pacemaker runaway risk mitigated in modern systems.
- Improved component reliability
- Runaway protection circuit inhibits high pacing rates >180bpm
Define the pacemaker syndrome with respect to DR systems.
Signs and symptoms associated with inadequate timing of A and V contractions.
Define Orthodromic Pacemaker Tachycardia.
The opposite to PMT in terms of propogation.
Instead of V pacing respondent to Atrial sensed events (as with PMT). There is A-pacing respondent to the conducted QRS being sensed inappropriately (This is rare).
