Transcript Appendix-E-Pacemakers - McLaren

Basic Arrhythmias
Seventh Edition
Gail Walraven
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Appendix E
Pacemakers
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Artificial Pacemaker
• A device used to provide artificial
electrical stimulus to myocardial tissue
to induce myocardial depolarization
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Purpose of a Pacemaker
The primary purpose is to maintain an
adequate rate if the inherent pacemaker
is too slow, or if conduction is blocked.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Spikes
• Each time a pacemaker fires, it
produces a spike on the EKG.
• To evaluate effectiveness, look at the
relationship between the pacemaker
spikes and the patient’s own
complexes.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Components
• Power Source: battery unit called a
pulse generator
• Conducting Wire: electrode that goes
to the heart to provide the stimulus
• Return Wire: wire that returns to
battery unit to complete the electrical
circuit
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Types of Pacemakers
• Temporary
– transvenous
– transcutaneous
• Permanent
– implanted
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Placement
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Capture
Depolarization of the heart in response to
an artificial stimulus.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Chambers Paced
• Atrial Pacemakers: stimulate only atria
• Ventricular Pacemakers: stimulate only
ventricles
• AV synchronous pacemakers: stimulate
both atria and ventricles
• Single-chamber pacemakers: stimulate
either atria or ventricles, but not both
• Dual-chamber pacemakers: stimulate
both atria and ventricles
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Smart Pacemaker
Technology enables these devices to
sense intrinsic electrical activity and
respond appropriately by pacing or
withholding stimulation in synchrony with
patient’s rhythm.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacing Response
• Triggered: fixed-rate, fires regardless of
underlying activity
• Inhibited: demand pacemaker, fires
only when needed
It is possible for a pacemaker to be both.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Classification
• Chamber Paced
• Chamber Sensed
• Response
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Classification
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Common Single-Chamber
Pacemakers
• Ventricular Demand (VVI)
• Atrial Demand (AAI)
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Common Single-Chamber
Pacemakers
• AV Synchronous (VDD)
• AV Sequential (DVI)
• Optimal (DDD)
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Assessment of Pacemaker
Function on the EKG
1. Identify pacemaker spikes.
2. Look at relationship between spikes and
patient’s complexes.
3. Is pacemaker doing what it is supposed to
do?
4. Is rate reasonable?
5. Are spikes competing or falling near T
waves?
6. Is pacemaker functioning consistently and
reliably?
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Malfunction
Failure to Capture
• Pacemaker fires, but no capture
occurs.
• EKG has spike not followed by
complex.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Malfunction
Competition
• Artificial pacemaker fires without
regard to underlying rhythm.
• Both pacemakers compete for control
of the heart.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Malfunction
Runaway Pacemaker
• Pacemaker fires too rapidly but still
captures.
• Caused by malfunctioning impulse
generator.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Malfunction
Battery Failure
• Battery has insufficient power to initiate
pacemaking stimulus.
• EKG shows absence of spikes in a
rhythm normally paced.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Treatment of Malfunctioning
Pacemaker
• Pacemakers are a treatment, so they
aren’t treated when they malfunction.
• When a pacemaker malfunctions,
treatment is directed at the patient and
the underlying rhythm.
• Replacement of the malfunctioning
pacemaker might be an option.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Paced Complexes
Pacemakers often supplement, rather than supplant, the patient’s
own rhythm. This rhythm strip shows a ventricular demand
pacemaker that fires occasionally to supplement the patient’s
underlying atrial fibrillation. Complexes C, D, E, and G are the
patient’s normally conducted beats (note narrow QRS
complexes). Complexes A, B, and F are initiated by the artificial
ventricular pacemaker (note spikes preceding each wide QRS).
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Rhythms
(Ventricular)
A properly functioning pacemaker will show a sharp spike,
followed immediately by depolarization of the chamber it is
intended to pace. This rhythm strip shows ventricular pacemaker
capturing every beat. Note absence of mappable P waves and
sharp spikes followed immediately by wide QRS complexes.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Rhythms
(AV Synchronous)
This rhythm strip shows an AV synchronous pacemaker capturing
every beat. Note pacemaker spikes preceding both atrial and
ventricular depolarization.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Properly Functioning Ventricular
Demand Pacemaker
The pacemaker is set to fire whenever the patient’s intrinsic rate
falls below 60 bpm. The first three complexes show the patient’s
heart depolarizing at about 68 bpm, so the pacemaker inhibited
itself. It kicked in at the fourth complex when the rate dropped,
and continued to pace at a rate of 60 bpm.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Failure to Capture
The underlying rhythm is atrial fibrillation, and the ventricular
pacemaker is set at an unusually slow rate of 44 bpm. It fails to
sense the patient’s own complexes and continues to fire regularly,
regardless of underlying ventricular activity. When the pacemaker
stimulus finds the ventricles refractory, it fails to capture.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Competition
This strip shows pacemaker spikes at a rate of 100 bpm, with an
underlying ventricular tachycardia/fibrillation. The pacemaker is
competing for control of the heart, but the irritable ventricular foci
are winning.
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Sample Pacemaker Strips
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Fully Functional Atrial Pacemaker
Showing 100% Capture
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Ventricular Pacemaker Showing
100% Capture (with Underlying
Complete Heart Block)
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
AV Sequential (DVI)
Pacemaker
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Properly Functioning Demand
Pacemaker
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
DDD Pacemaker in AV
Sequential Mode
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Sinus Rate Accelerates and
Regains Control from Ventricular
Demand Pacemaker
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Pacemaker Fails to Depolarize
Consistently, Indicating Lead
Fracture or Displacement
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Ventricular Pacemaker with
100% Capture
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Atrial Pacemaker with 100%
Capture
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Non-capturing Pacemaker Competing
with Supraventricular Rhythm in First
Part of Strip, Converting to
Ventricular Tachycardia Competing
with Pacemaker at End of Strip
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Ventricular Demand
Pacemaker
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ
Ventricular Pacemaker
Showing 100% Capture
Gail Walraven, Basic Arrhythmias, Seventh Edition
©2011 by Pearson Education, Inc., Upper Saddle River, NJ