Pacemaker Flashcards
How are pacemakers classified?
Pacemakers are classified by a five-letter code, each letter of
which denotes a particular function of the pacemaker. The last
two letters represent the programmability and antiarrhythmic
functions of the pacemaker and are commonly omitted. The
first three letters of the code represent the chamber-paced,
chamber-sensed, and response to sensing respectively. For
both the chamber-paced and chamber-sensed letters the
legend is as follows: 0=none, A=atrium, V=ventricle, D=Dual
(both atrium and ventricle). For the letter representing the
response to sensing, the legend is 0=none, T=triggered,
I=inhibited, and D=dual (both triggered and inhibited).
Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s
Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill;
2013: 432.
What are the preoperative concerns you should have
for a patient presenting for surgery who has a
pacemaker?
Continuous ECG monitoring is required with special attention
paid to the patient’s preoperative rhythm, rate, and
hemodynamic status because electrocautery can electrically
reset a pacemaker (older models are more susceptible).
Placing a magnet over the pacemaker during surgery can either
temporarily or permanently reset the device depending upon the
age and model of the device, so it is important to contact the
electrophysiology service to arrange for interrogation of the
device both before and after surgery to ensure that it is returned
to its original program parameters.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1281.
During the perioperative evaluation, you discover
that a patient with a pacemaker occasionally
experiences dizziness while exercising his chest
muscles. What can you deduce from this
This indicates that myopotentials may be inhibiting the
pacemaker. From this information, you know that muscle
fasciculations from succinylcholine should be avoided to
prevent inadvertent pacemaker inhibition.
Nagelhout JJ, Plaus KL. Nurse Anesthesia. 5th ed. St. Louis,
MO: Elsevier Saunders Company; 2014: 359.
What do the pacemaker codes VVI, V00, and DDD
mean?
The three letters in the pacemaker code indicate the chamberpaced,
chamber-sensed, and response to sensing in that order.
The two most common pacemaker codes are VVI and DDD.
VVI indicates that the ventricle is paced, that the pacemaker
senses electrical activity in the ventricle, and that the
pacemaker’s discharge is inhibited if it senses a natural
electrical impulse in the ventricle. DDD indicates that the
pacemaker is capable of generating a pacing impulse in both
the atrium and the ventricle, senses natural electrical impulses
in both the atrium and ventricle, and can trigger or inhibit
impulses in both the atrium and ventricle. V00 indicates that the
pacemaker is in asynchronous mode which means that it is
capable of pacing the ventricle only and cannot sense or
respond to normal electrical signals in either the atrium or
ventricle.
Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s
Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill;
2013: 432.
What is AV sequential pacing?
Ventricular pacing alone can result in a drop in cardiac output
because the contribution of atrial contraction to ventricular filling
is lost. If the atrial conduction system is inadequate, the
pacemaker can be set to stimulate the atria to contract via one
lead and timed with the ventricular stimulation by another lead
to return the atrial kick that was lost and preserve normal
cardiac output.
Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s
Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill;
2013: 432.
What types of procedures or events can interfere
with a pacemakers ability to function correctly?
Electromagnetic interference can occur with electrocautery,
radiofrequency ablation, MRI, and radiation therapy and can
result in malfunction of the device. Also, some patient monitors
and ventilators can interfere with the rate-adaptive mechanism
of pacemakers.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 63.
A patient with a pacemaker presents for emergency
surgery. There is no time to adequately interrogate
the pacemaker and determine if placing a magnet
over it is safe. What precautions can be taken to
minimize the risk of interference with the device?
Electrocautery should be used sparingly if possible. Avoid
proximity of the cautery tool to the pulse generator and leads.
Position the current return pad so that current from the cautery
doesn’t pass through the pulse generator or leads towards the
return pad. Use short cautery bursts with the lowest possible
energy setting. Use bipolar cautery to reduce the range through
which the current disperses. Have the pacemaker evaluated by
the electrophysiology service as soon as possible after surgery
to make sure it is functioning properly.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 1724.
