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Pacemaker: Transthoracic Cardiac Pacing 1148.e1

Pacemaker: Transthoracic Cardiac Pacing Client Education
Sheet
VetBooks.ir

anesthesia. This is a precaution in the event
Difficulty level: ♦♦♦
of patch electrodes, causing inconsistent
of bradyasystole during induction. • Most common error is suboptimal placement
Synonym • Ensure clear ECG tracing to allow accurate pacing. Ensure placement directly over the
Temporary cardiac pacing sensing of dog’s intrinsic heartbeat before palpable cardiac impulse beats. Readjustment
starting transthoracic pacing. of patch electrodes may be necessary.
Overview and Goal • Another common error is a suboptimal
Noninvasive, rapidly implemented, temporary Possible Complications and ECG recording, resulting in undersensing
cardiac pacing system used for support of heart Common Errors to Avoid and oversensing of the patient’s intrinsic
rate and blood pressure (BP) in animals that • Most common complications are skeletal cardiac rhythm.
are under anesthesia and that have medically muscle twitching and pain associated with • Obese dogs or dogs with pleural space disease
refractory bradyarrhythmias. Typical applica- pacing stimulus. may require higher than expected pacing Procedures and Techniques
tions are stabilization for permanent pacemaker • Pain or distress experienced in awake dogs threshold.
implantation and emergency treatment of requires rapid induction of general anes-
life-threatening bradyarrhythmias. thesia for continued use of the temporary Procedure
pacemaker. Analgesia (e.g., opiate) is also ECG and pacing patch electrodes are in place
Indications recommended. before induction for permanent pacemaker
• Support of heart rate and BP during general • Skeletal muscle twitching, more pronounced implantation. The pacing system is usually
anesthesia for dogs with medically refractory in smaller dogs, may require neuromuscular turned on shortly after induction of anesthesia.
bradyarrhythmias undergoing permanent blockade to lessen the jerking of forelimbs • ECG leads are connected to the dog, and a
pacemaker implantation or another surgery and chest during the surgical procedure. good-quality ECG tracing is obtained.
unrelated to pacemaker implantation
• Emergency treatment of hemodynamically
unstable, medically refractory, complete
atrioventricular (AV) block until more
definitive therapy can be instituted
• Bradyasystolic arrests (e.g., digoxin overdose)
Contraindications
Essentially no contraindications
Equipment, Anesthesia
• General anesthesia and tracheal intubation
required
• Continuous electrocardiogram (ECG)
and transthoracic pacing system required,
including disposable adhesive transthoracic
patch electrodes. Newer versions of trans-
thoracic patch electrodes are available that
allow noninvasive cardiac pacing and can
be used for defibrillation, synchronized
cardioversion, and ECG monitoring PACEMAKER Anesthetized, laterally recumbent dog with properly placed electrode patches and connection
to pacing system. (From DeFrancesco TC, et al: Noninvasive transthoracic temporary cardiac pacing in dogs. J
(p. 1096) Vet Intern Med 17:663-667, 2003.)
• A #10 clipper blade (to shave the hair from
the left and right precordia [area of the thorax
overlying the heart])
• Occasionally, a neuromuscular blocker
(and hence mechanical ventilation) may be
desirable to limit jerking of skeletal muscles
during a surgical procedure.
Anticipated Time
Pacing system can be attached and pacing
implemented in just a few minutes, especially
in urgent situations.
Preparation: Important
Checkpoints
• Have pacing system prepared (patch
electrodes on chest and ECG monitoring
ongoing) at induction of general anesthesia
in dogs undergoing permanent pacemaker
implantation or other dogs at risk for PACEMAKER Animal undergoing transthoracic pacing while the neck is aseptically prepared for permanent
bradyarrhythmic complications with general transvenous pacemaker implantation.

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