Implantable Cardiac Devices Flashcards
Who was responsible for the first external pacemaker?
Mark Lidwell, Albert Hyman
What was created in 1957, and by whom?
Earl E. Bakken produced the first battery-operated wearable pacemaker
What was introduced in the 2000s, and what benefit did it provide?
bi-ventricular pacing, paces both ventricles to go at the same time
What visual cue represents an unfired beat from the temporary pacemaker?
a vertical dotted line
What can happen if the sensitivity threshold on a temporary pacemaker is set too low?
ventricular fibrillation
How do you know where to set sensitivity?
half of the
What does VVI represent?
The ventricle is being paced, the ventricle is being sensed, the ventricular signal from the pacemaker is being inhibited.
What does VAT represent?
The ventricle is being paced, the atria is being sensed, the (?) signal from the pacemaker is being triggered.
What does DVI represent?
Both the atria and ventricles are being paced, the ventricle is being sensed, the ventricular signal from the pacemaker is being inhibited.
What are some benefits of choosing a temporary transvenous pacemaker over a transcutaneous pacemaker?
more comfortable, will move around less (reduced likelihood of dislodging)
What are the three main purposes of a permanent pacemaker?
- restore rhythm/function
- improve QoL
- less time in hospital
What seven problems could a permanent pacemaker cause?
- systemic infection
- perforation
- tamponade
- mess with MRIs
- vascular occlusion
- cardiomyopathy cause by the pacemaker
- lead revision/extraction/device/replacement
Which part of the unipolar-lead pacemaker is the anode?
the pulse generator
How can you distinguish a unipolar-lead pacemaker from a bipolar-lead pacemaker?
bigger pacemaker spikes
Where is the anode located in the bipolar lead pacemaker?
ring electrode
What type of fixation involves screwing?
active
What problems do using the subclavian vein in the transvenous insertion procedure have?
sharp angle within vein can compress and damage lead
What does voltage represent?
the strength/amplitude of the pacing pulse
What does current represent?
how fast the charge goes through the circuit
What are the three main sources of resistance/impedance?
- the wire
- the tip of the pacemaking wires
- the cluster of ions where the cathode of the pacemaker meets the tissue of the heart
What is a good range for impedance values to stay in ?
300 ohms - 3000 ohms
Which electrical value is not directly controllable for a pacemaker?
current
What is Ohm’s law?
I = V x R
What will the ECG of a person who has a dual-chamber sensing pacemaker usually look like?
an ECG with NSR
What is the purpose of the post-ventricular atrial refractory period?
prevent atria from responding erroneously (e.g. PACs, retrograde P-waves. far-field ventricular signals)
What problems can come up with VDD pacing?
If the atrial rate falls below the LRL programmed in, AV synchrony will be lost, which can drain the battery faster.
What can happen in DDI mode?
If the atrial rate becomes higher than the LRL, while the pacemaker is forcing the ventricles to beat at the LRL-set pace, so atria and ventricles stop working in tandem.
What is DDI mode good for?
atrial tachyarrhythmias (e.g.) aFib, DDI mode won’t let the ventricles try to keep up with an extremely high atrial rate
How does the single chamber pacemaker decide how to act on the intrinsic rhythm?
if intrinsic rhythm>LRL–> pacemaker inhibited
if intrinsic rhythm
How is VA calculated?
cycle length (60,000/HR) - AV delay length
Why is cross talk a problem?
If the atria are being sensed when the ventricles are supposed to be sensed, the pacemaker will inhibit ventricular activity, even when it is needed.
How is cross-talk prevented?
blanking periods
What is the total atrial refractory period?
AV delay + PVARP
The amount of time elapsed after impulse travels to AV node, and then the ventricles are allowed to repolarize
How would loss of capture present on the ECG?
see spikes with no depolarization waves with it
List examples of AV/refractory period-based pseudomalfunctions.
- ventricular safety pacing
- managed ventricular pacing
- blanking
- rate-adaptive AV delay
- auto PVARP
- PVC response
- noncompetitive atrial pacing
- ventricular sense response pacing
How would atrial oversensing present on the marker channel of a paced ECG?
The marker channel will have AS markers but the ECG will have no p-waves in the same area.
Normal range of impedance values?
200-2000 ohms
How is lower rate interval calculated?
60,000/bpm
What does “slew rate” mean?
Slew rate represents how much the voltage changes over a period of time
What are the 3 components of the implantable pulse generator?
- battery
- connectors
- circuitry
What does the first column of the universal code represent?
chamber that is being paced
What are the 4 main indications for a pacemaker?
- symptomatic bradycardia
- sick sinus syndrome
- CHB
- chronotropic incompetence
What 4 steps are part pf the pacemaker interrogation process?
- check lead integrity
- troubleshoot
- check device usage
- check battery life
