Education Newsletter December 2022: Pacemakers | Cardiovascular Intensive Care Unit

JoAnna Bentsen

December 20, 2022

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Temporary Pacing in the CVICU

Modalities of Temporary Pacemakers and the Utilization within the CVICU:
- Epicardial Wires
-Trans-Venous Pacemaker
- Pacing Swans

Concepts of Pacing

Beginning with the modes of pacing, the primary concepts are:
1. Where is it pacing ?
2. Where is it sensing the hearts intrinsic rhythm?
3. What does the pacemaker do if the pacemaker senses an intrinsic heart beat ?

These concepts translate to a three-letter abbreviation that tells you what type of pacing your patient is requiring

P- Dictates where the PACEMAKER is sending electrical impulses to.
S- Where is the pacemaker looking to pick up on what the HEART can do by itself.
R- How does the pacemaker respond when it senses an intrinsic heartbeat.

4 Options for the Pacemaker Response:
Inhibit- when the pacemaker sees a beat, it will stop the pacemaker (will only fire when needed)
Triggered- Pacemaker will trigger an action when it sees the heartbeat ex: when there is a P-wave the pacemaker fires to stimulate ventricular contraction. Typically, not chosen alone because you want the heart to work on its own as able.
Dual- (does both) When the pacemaker sees a beat in the atrium it may TRIGGER a beat to the ventricles. If the pacemaker sees a beat to the ventricles, it may INHIBIT the pacemaker from firing.
None- emergency or asynchronous pacing. Not utilizes routinely in the CVICU.

In the ICU, providers have the option to target the pacemakers to SINGLE or DUAL Chambers. (only the atrium, or only the ventricles) Based on what mode is set, the pacemaker will be sending signals to the atrium, ventricles, or both.

Examples of Pacemaker Modes:

Single Chamber Pacemaker Modes:
1. Ventricular: (V Pacing)

VVI- Pacing the Ventricle, Sensing the Ventricle, Inhibiting the pacemaker when the heart beats independently.
- Pacemaker will look at the ventricles and fire when the heat does not do it independently.

2. Atrium: (A Pacing)

AAI- Pacing in the Atrium, Sensing in the Atrium, Inhibiting the pacemaker when the heart beats independently
- Pacemaker will look at the atrium and fire when the heart does not do it independently
- ** note that if the patient does not have adequate conduction through ventricles, this mode will not work**

3. Dual Chamber Pacemakers: (AV Pacing)

DOO- Pacing atrium and ventricle NO sensing and NO inhibition. This is emergency pacing.
- Asynchronous mode is most commonly utilized within the OR, not a typical modality for the ICU
DDD- Pacing AND Sensing the atrium and ventricle, Inhibiting the pacemaker when the heart intrinsically beats AND Triggering the pacemaker to work if the atrium OR ventricle does not fire.
- This mode is going to sense for activity in both chambers and fire when it has determined the heart will not on its own

DDI- Pacing and Sensing the atrium and ventricle. Inhibits when the heart has its own activity. The ONLY time ventricles will be paced, are when an ATRIAL pacer spike precedes it.
- Think about patients in afib, if each atrial stimulus caused ventricular beats, patient would have RVR continuously. So this pacer mode only allows for ventricle beats that are fired after the pacemaker provides an atrial beat.

Pacemaker Settings

(buckle up, this is where we all get confused)

1. Rate: If your patients intrinsic heartrate drops below this set number, the pacemaker will fire (measured by time since last beat)

2. Mode: ** Depending on if your patient has A wires, V wires, or both, our pacemakers can utilize SINGLE or DUAL chamber pacemaker modes **

Know what mode you're ordered to be in, verify it and ASK if it is different

3. Output: Measure of how much energy the pacemaker must send to signal CAPTURE in the heart: measured in mA (milliamps) Atrial max 20 Ventricle Max 25

Output may be affected by age of leads, patient's acid/base status and medications.
Errors here include loss of capture

4. Sensitivity: Measure of how much energy, measured in mV (millivolts) the pacemaker is using to see the patient's intrinsic heartbeat.

In other words, will the pacemaker even see your heart trying to work?

I've lost capture, what do I do?!
If your pacemaker is not capturing, this means the stimuli sent out by the pacemaker is not enough to initiate depolarization of your atria or ventricles. So what do you do? INCREASE the stimuli!

Here you can see that the pacemaker sent signals, but the ventricles did not react.
In this situation turn UP the mA until you have capture by your pacemaker. Depending on what chamber you are pacing will determine which mA needs to be increased

Speaking about sensitivity.... What's this about a fence??
When talking about sensitivity, we are thinking about what the pacemaker is seeing. To some people, the visual of a fence is helpful.

Undersensing
If the pacemaker is being insensitive to the patient's heart then it will never sense the patient's R waves..(sensitivity fence is set too high)

On the monitor, this will be seen as inappropriate pacemaker spikes within the QRS or after the QRS
How do we fix it? Make the pacemaker more sensitive by LOWERING the mV. Now the pacemaker can see the patients R waves. (increasing the sensitivity)

Oversensing
If the pacemaker is being too sensitive, then every small electrical deflection will be seen as the patient's R wave...(sensitivity fence is set too low)

On the monitor, you will see pauses between capture because atrial contractility is being seen as the QRS complex
How do we fix it? Make the pacemaker less sensitive by INCREASING the mV. Now the pacemaker will only see the R waves. (Decrease the sensitivity)

Now that we've cleared that up... What are my responsibilities with my Epicardial Pacemaker?

1- Identify the wires that you have. Atria are on the RIGHT. Ventricles are on the LEFT.
**Always know what you have!!**
You may have a ground wire attached to the skin. This wire should never be hooked to the black pole. Why? Pacing skin wont help anyone!
2- Determine what mode you're in, and if that matches your orders.
3- If your patient is pacemaker dependent, have a backup pacemaker in the room, programmed identical to what you are currently using.
** Batteries get changed at 0700 every morning**
4- Providers may check patients underlying rhythm every shift, if the last known underlying rhythm is not life-sustaining, the RN should not check the underlying rhythm alone.
5- Document current settings and any changes
6- Pacemaker wires should be *nested* for the first 48 hours of surgery. This means connected to extension tubing and hanging by the pacemaker box. With orders, they may be isolated and taped at the patient's chest.

But seriously... I am supposed to make changes to those things??

Per the CVICU standards of care, the bedside RN may make changes to both output (mA) and sensitivity (mV). If you are not capturing? Turn up your mV, if you are under or over pacing? change your sensitivity.

if you are UNCOMFORTABLE making changes, this is the space to ask questions in! Elevate questions to charge nurses, providers, or member of the leadership team!

Transvenous Pacing

Trans-Venous Pacemakers are inserted via the internal jugular vein or femoral vein and floated into the heart with aid of a balloon. This functions as a SINGLE chamber pacemaker.

Nursing Considerations include
1. Do NOT use the cordis infusion port on a temporary pacemaker
2. These patients will be restricted to their bed
3. Prepare for hypotension and decreased cardiac output secondary to the bypassing of atrial kick in a normal heart conduction.

Pacing Swan

Pacing swans are frequently utilized in our minimally invasive cardiac surgeries. For this intention the swan is utilized to defibrillate the heart during and after surgery.

Pacing swans may not always be utilized for pacing purposes within the CVICU. SHOULD you be using your pacing swan, you will need clamps connecting your pacing leads to your temporary pacemaker. These are in the cell and also can be obtained via the charge nurse.

This modality can be used as a single or double chamber pacemaker.

New Faces in the ECMO Corner

With a large number of new ECMO nurses in the house (woo!) I wanted to recirculate some clinical pearls regarding ECMO Practice in the CVICU

Safety Checklist is completed at any handoff of the patient, prior to transport, at transport destination, and upon returning from a transport with the RN and perfusionist.
Ensure that Temperature alarms for the Phillips monitor are switched ON for patients on ECMO.
RN's at the bedside are NOT allowed to make changes to FD02, Sweep Gas or RPM. These changes can be made by CVICU Intensivists, ECMO Fellows, Midlevel Providers or Perfusionists.
- You will monitor for the effect of these changes as the bedside RN and elevate concerns appropriately, but physical changes to the therapy prescription must be made by a Provider level of the ECMO Team.
- If you have any questions, please reach out to lynne.craig@vumc.org, me, or a member of the leadership team!

The Nurse Wellness Committee is Re-Launching and looking for representation from units, and any ideas about how to enhance wellness from the nursing front lines! This committee meets monthly

If you're interested or have any ideas, please fill out this survey below!
https://redcap.vanderbilt.edu/surveys/?s=CCFFMXLMPC7EARN3

There are multiple modalities for temporary pacing in the CVICU, the most common being via epicardial wires post cardiac surgery.
Pacemaker settings are determined by three concepts: chamber paced, chamber sensed and pacemaker response to intrinsic rhythm
The four settings your pacemaker can tell you are Rate, Mode, Output and Sensitivity. The nurse may make changes to output and sensitivity.
Fixing capture errors are completed by increasing your output (mA)
Adjusting sensitivity is identified by if you are under or over pacing the patient.
As the nurse you have multiple responsibilities regarding the temporary pacemaker.
Transvenous pacemakers are only able to pace a single chamber
Pacing swans are not always utilized in that function within the CVICU
With multiple new ECMO users, please remember the nurse scope regarding ECMO and that any change to therapy are completed by a provider
IABP Super user class is January 5th sign up in LMS
Nurse Wellness Committee is asking for feedback!!

CVICU INQUIRER | December 2022
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