Page 692 - Cardiac Nursing

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668 PA R T I V / Pathophysiology and Management Disease
slower rate. Some pacemakers remain in the asynchronous pacing modulation by programming to VVI or DDD before surgery, be-
mode for the entire duration that the magnet is in place, whereas cause mechanical ventilators, bone hammers, surgical saws, and
others only pace asynchronously for a certain number of beats and other equipment in the surgical environment may trigger the phys-
then revert to normal operation. It is possible to program the iological sensors and result in rapid pacing.
magnet operation off in some pacemakers, although this is rarely
done. Because of the wide variety of potential responses to mag- Nonmedical Sources of EMI. Pacemakers can be adversely
net application, it is advisable to know what pacemaker is present affected by EMI in the environment, and patients should be
and what the programmed parameters are whenever possible taught about potential pacemaker interactions with common
when using a magnet. sources of EMI. Security systems or antitheft devices in depart-
Another indication for magnet use is to terminate a pace- ment stores can potentially interact with pacemakers and cause in-
maker-mediated tachycardia (PMT) in a dual-chamber pace- termittent inhibition of pacing output, inappropriate atrial track-
maker (see section “Dual-Chamber Pacing”). When using the ing, or asynchronous pacing. 25 Patients should be cautioned not
magnet, the nurse should have the patient on a cardiac monitor to linger close to a security system but to pass through it and then
and must be aware of the potential danger of a pacing spike falling move away. Metal detectors used in security systems in airports
in the vulnerable period and causing ventricular arrhythmias. A and other places can potentially interact with pacemakers, but this
defibrillator should be immediately available whenever a magnet interaction is rare. It is generally safe for people with pacemakers
is used on a permanent pacemaker. or ICDs to walk through a metal detector gate even though the
alarm may be triggered by the device. People with implanted
Pacemakers in the OR. The biggest concern regarding devices can request a manual search rather than a hand-held metal
pacemakers in the OR is the potential effect of electromagnetic in- detector search.
terference (EMI) on pacemaker operation. Cautery used during Cell phones, personal digital assistants, laptop computers, and
surgery is a type of EMI that can cause abnormal behavior of the other wireless devices are a potential source of EMI that can in-
pacemaker. Although modern pacemakers are heavily shielded hibit pacemaker output, cause asynchronous pacing, or cause in-
and protected from many sources of EMI, it is still possible for ex- appropriate ventricular tracking in a dual-chamber device. 25
traneous signals to enter the pacemaker when detected by the pac- Keeping a cell phone at least 6 inches away from the pacemaker
ing leads. Bipolar pacing systems are less likely to be affected than pulse generator prevents interactions. Patients should avoid carry-
unipolar systems because the sensing circuit in a bipolar system is ing their cell phone in a pocket near the pulse generator and
much smaller than that in a unipolar system. Possible responses to should use the ear opposite the pacemaker when talking on a cell
EMI include: (1) inhibition of pacemaker output; (2) triggering phone. It is reasonable to consider the hand used to hold a cell
of pacemaker output at rapid rates; (3) asynchronous pacing; (4) phone when selecting the site for pacemaker implantation in in-
mode resetting; (5) damage to the circuitry in the pacemaker; or dividual patients.
25
(6) delivery of inappropriate shocks if the device is an ICD. The Household appliances are safe for use by patients with pacemak-
most common responses to EMI in the OR are inhibition of pac- ers, as are other commonly used electrical or motor-driven appliances
ing or reversion to a “noise mode,” usually VOO or DOO pacing like lawn mowers, leaf blowers, and small tools (drills, saws, etc.). Al-
(asynchronous pacing). Inhibition of pacing occurs when the most all interactions with household appliances (especially washing
pacemaker senses the cautery and interprets those signals as in- machines) occur with improper grounding of the appliance. 25
trinsic ventricular activity. This feature can result in asystole if the Cardioversion and Defibrillation. Patients with pacemak-
patient is pacemaker-dependent with no reliable underlying ers can be safely cardioverted or defibrillated if precautions are
rhythm and is the most worrisome concern when dealing with taken to protect the pacemaker from high-energy electrical forces.
pacemakers in the OR. Many pacemakers revert to asynchronous Paddles or defibrillation pads should not be placed directly over
pacing when they sense electrical “noise” from cautery or other the pulse generator. Placing the paddles or pads in the ante-
sources of EMI. This feature allows pacing to occur in an asyn- rior–posterior position is preferred over the standard transthoracic
chronous mode, creating the potential problem of pacemaker placement (refer to Fig. 28-4, which illustrates anterior–posterior
output occurring during the vulnerable period of ventricular re- pad placement for external pacing). Use of lower energy shocks is
polarization and resulting in VF. preferable over higher energy shocks whenever possible. The pace-
There are several interventions that can reduce the potential ad- maker should be interrogated after cardioversion or defibrillation
verse effects of EMI during surgery. If cautery is to be used, then to make sure it is still programmed and functioning as intended.
place the grounding pad as far away from the pulse generator as pos-
sible (e.g. on a leg rather than on the chest or back), and place it on Temporary Pacemakers
the opposite side of the body from the pacemaker. Use cautery in In the care of patients with temporary pacemakers, the following
short bursts rather than long, continuous applications. Observe the additional considerations become important.
monitor for pacemaker response to cautery, and if cautery appears
to cause inhibition of pacing place a magnet over the pacemaker Insertion Site Care. A temporary pacing catheter is usually
while cautery is being applied. A defibrillator and other emergency inserted through a venous sheath that is sutured to the skin and
equipment should be immediately available during surgery. It is ad- treated as any central venous catheter. Maintaining a clean, dry in-
visable to interrogate a pacemaker both before and after surgical sertion site is important to prevent infection, and hospital policies
procedures involving cautery or other sources of EMI (i.e. high-in- governing the care of central venous catheters and dressings
tensity radiation, radiofrequency ablation, lithotripsy) to verify pro- should be followed. If the pacing catheter is placed via a femoral
grammed parameters before surgery and make sure they have not vein, then the patient needs to be on bed rest with the affected leg
changed after surgery. If the pacemaker is programmed to a rate- straight and head of bed elevated no more than 20 degrees while
modulated mode (VVIR, DDDR), then it is wise to disable rate the femoral sheath is in place.