Page 691 - Cardiac Nursing

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C HAPTER 2 8 / Pacemakers and Implantable Defibrillators 667
positive terminal of the cable; for ventricular pacing, connect appropriate pacemaker function by looking at the ECG or
one ventricular pacing wire to the negative terminal of the pac- rhythm strips. The next section of this chapter covers ECG analy-
ing cable and the other ventricular wire to the positive terminal sis of pacemaker rhythm strips to assist bedside practitioners in
of the cable. evaluating pacemaker function. It is beyond the scope of this
3. Set the rate at 70 to 80 bpm or as ordered. chapter to discuss pacemaker follow-up in a clinic or office
4. Set the output at 10 mA for atrial pacing and 5 mA for ven- setting.
tricular pacing, then determine stimulation threshold and set An important function for nurses or monitor technicians is to
two- to three-times higher. document significant bradycardias that may require pacemaker
5. Set the sensitivity at the lowest possible number for atrial pac- therapy and to relate these bradycardia events with clinical symp-
ing and at 2 mV for ventricular pacing. toms whenever possible. The guidelines for pacemaker insertion
state, “definite correlation of symptoms with a bradyarrhythmia is
Dual-Chamber Temporary Pacing required to fulfill the criteria that define symptomatic bradycar-
1
Dual-chamber pacing can be performed through epicardial-pac- dia.” Many insurance companies will not cover the cost of pace-
ing leads or with transvenous atrial and ventricular leads. Transve- maker insertion without good clinical documentation of the need.
nous dual-chamber pacing is not often performed because of dif- Nurses and monitor technicians are in a prime position to be able
ficulties in placing temporary atrial leads and the unreliable to document the bradycardia event by mounting rhythm strips in
stability of atrial leads. Epicardial dual-chamber pacing is often the patient’s chart or getting a 12-lead ECG, and documenting
performed after cardiac surgery, but should be performed only symptoms that occur in conjunction with the bradycardia. Docu-
when there are two ventricular leads in place. Two ventricular mentation of hypotension, syncope or near syncope, dizziness or
leads allow for bipolar ventricular pacing and sensing, thus reduc- light-headedness, confusion, fatigue, exercise intolerance, and de-
ing the possibility that the ventricular lead will sense atrial output velopment of symptoms of HF associated with bradycardia is an
and inappropriately inhibit ventricular pacing (crosstalk). important nursing function.
Dual-chamber pacing modes available depend on the type of
pulse generator used for pacing. Older dual-chamber temporary Permanent Pacemakers
pulse generators (like that shown in Fig. 28-6A) allow only DVI Implantation of a permanent pacemaker is often performed on an
pacing. The newer dual-chamber units allow for DDD, DVI, outpatient basis, but some patients are kept overnight for obser-
DDI, and VDD pacing in addition to the single-chamber options vation. The procedure is performed under local anesthesia in the
AAI, AOO, and VVI. cardiac catheterization laboratory, electrophysiology laboratory, or
To initiate dual-chamber pacing with epicardial leads:
the OR, and it takes from 1 to 5 hours to complete depending on
1. Connect two pacing cables to the top of the pulse generator: the number and location of pacing leads being inserted. In addi-
one to the atrial terminal and one to the ventricular terminal. tion to routine postoperative care given to any surgical patient,
2. Connect the atrial pacing cable to the atrial pacing wires: one permanent pacemaker insertion usually requires that the patient
atrial wire to the positive terminal and one atrial wire to the immobilize the operative arm in a sling for the first 24 hours to
negative terminal. prevent lead dislodgment. The nurse must be aware of the poten-
3. Connect the ventricular pacing cable to the ventricular wires: tial complications of pacemaker insertion, including the potential
one ventricular wire to the positive terminal and one ventricu- for cardiac perforation leading to tamponade, and monitor for
lar wire to the negative terminal. those complications. Patient teaching includes information about
4. Select dual-chamber pacing mode desired (if option is pro- pacemaker function, how to count the pulse, and importance of
vided): DDD, DDI, DVI, VDD. The DDD mode is almost al- follow-up visits to the physician. Because patients are discharged
ways used. so soon after the procedure, they should be told to take their tem-
5. Set AV delay at 150 milliseconds or as ordered. perature and monitor the insertion site for signs of infection.
6. Set atrial output at 10 mA and ventricular output at 5 mA,
Using a Magnet With a Permanent Pacemaker. Occa-
then determine stimulation threshold for both chambers and
sionally, the nurse is asked to place a pacemaker magnet over the
set output two- to three-times higher than threshold.
permanent pulse generator. Use of a magnet usually requires a
7. Set atrial or ventricular sensitivity as necessary, depending on
physician’s order or is covered by a written protocol detailing con-
pacing mode selected (atrial sensing occurs only in DDD,
ditions under which a magnet can be used without a direct order.
DDI, and VDD dual-chamber modes).
A magnet inactivates the sensing circuit of a permanent pace-
a. Set atrial sensitivity at 0.5 mV.
maker and causes it to revert to the asynchronous mode of pacing.
b. Set ventricular sensitivity at 2 mV.
This may be performed to verify a pacemaker’s ability to pace
when it is being inhibited by a patient’s own natural rhythm.
Nursing Considerations With a magnet in place, the pacemaker paces at a fixed rate in
competition with the patient’s rhythm, thus verifying the pace-
Nursing care of patients with pacemakers requires an understand- maker’s ability to deliver pacing stimuli. When a paced impulse
ing of how pacemakers work and what to expect the pacemaker to happens to fall at a time when the ventricle is able to respond, cap-
do depending on how it is programmed. Clinicians working in ture should occur, verifying the pacemaker’s ability to capture. A
pacemaker follow-up clinics or physician offices have the advan- magnet may also be used to evaluate battery status if a pacemaker
tage of being able to use the pacemaker programmer and view in- is nearing its end of service. In some older pacemakers the primary
tracardiac electrograms and marker channels to help evaluate indicator of battery depletion is a change in the magnet-induced
pacemaker function. Bedside nurses in most acute care facilities pacing rate. Some models of pacemakers pace at a faster rate for
do not have access to programmers and must be able to evaluate the first several beats after magnet application and then pace at a