Cardiology for Dr. Pelaez

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Pacemaker

• Cardiology for Dr. Pelaez
• By Sai Kumar Reddy
• American International Medical University,
  St.Lucia

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Pacemaker

• A pacemaker is a battery-powered device about the
  size of a pocket watch that sends weak electrical
  impulses to set a pace so that the heart is
  able to maintain a regular heartbeat.

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Anatomy Physiology of Pacemaker
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Types of Pacemakers

• Single-chamber pacemakers stimulate one chamber
  of the heart, either an atrium or more often a
  ventricle.
• Dual-chamber pacemakers send electrical impulses
  to both the atrium and the ventricle and pace
  both chambers. A dual-chamber pacemaker
  synchronizes the rhythm of the atria and
  ventricles in a pattern that closely resembles
  the natural heartbeat.

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Indications for Pacemaker

•  Absolute indications
• Sick sinus syndrome
• Symptomatic sinus bradycardia
• Tachy-brady syndrome
• Afib with slow ventricular response
• 3rd degree heart block
• Chronotropic incompetence
• Inability to increase heart rate to match
  exercise
• Prolonged QT syndrome

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I

• Relative indications are
• Cardiomyopathy
• Dilated
• Hypertrophic
• Severe refractory neurocardiogenic syncope
• Paroxysmal atrial fibrillation

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Pacemaker defects

• EKG abnormalities due to
• Failure to output
• Failure to capture
• Sensing abnormalities
• Operative failures

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Pacemaker Failure to Output

• Definition
• No pacing spike present despite indication to
  pace
• Etiology
• Battery failure, lead fracture, break in lead
  insulation, oversensing, poor lead connection.
• Atrial output is sensed by ventricular lead

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Pacemaker Failure to Capture

• Definition
• Pacing spike is not followed by either an atrial
  or ventricular complex
• Etiology
• Lead fracture or dislodgement, break in lead
  insulation, elevated pacing threshold, MI at lead
  tip, drugs, metabolic abnormalities, cardiac
  perforation, poor lead connection

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Pacemaker Sensing Abnormalities

• Oversensing
• Senses noncardiac electrical activity and is
  inhibited from correctly pacing
• Etiology
• Muscular activity (diaphragm or pecs), EMI, cell
  phone held within 10cm of pulse generator
• Undersensing
• Incorrectly misses intrinsic depolarization and
  paces
• Etiology
• Poor lead positioning, lead dislodgement, magnet
  application, low battery states, MI

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Pacemaker Complications

• Pacemaker syndrome
• Patient feels worse after pacemaker placement
• Presents with progressive worsening of CHF
  symptoms
• Due to loss of atrioventricular synchrony,
  pathway now reversed and ventricular origin of
  beat

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Pacemaker Operative Failures

• Due to pacemaker placement
• Pneumothorax
• Pericarditis
• Perforated atrium or ventricle
• Dislodgement of leads
• Infection or erosion of pacemaker pocket
• Infective endocarditis (rare)
• Venous thrombosis

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Electromagnetic Interference

• Can interfere with function of pacemaker
• Device misinterprets the EMI causing
• Rate alteration
• Sensing abnormalities
• Asynchronous pacing
• Noise reversion
• Reprogramming

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Electromagnetic Interference

• Examples
• Metal detectors
• Cell phones
• High voltage power lines
• Some home appliances (microwave)

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Caution

• If you have a pacemaker, you are not supposed to
  have an MRI (magnetic resonance imaging) test.

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Advancement of Technology in Medicine

• Newer pacemakers also can monitor your blood
  temperature, breathing, and other factors and
  adjust your heart rate to changes in your
  activity.

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Case

• CC Chills, rigors
• HPI
• 65 yom c/o fevers, chills, rigors x 1 day.
  Positive n/v and anorexia. Pt states he had
  recent pacemaker insertion 4 days ago for an
  arrhythmia.
• PMH
• HTN
• Arrythmia
• Hypercholesterolemia
• PSHx
• As stated above

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Case

• Physical exam
• Temp 101.2, HR 110, BP 90/55
• EKG
• Diagnosis?

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Case

• Pocket Infection
• Pacemaker insertion is a surgical procedure
• 1 risk for bacteremia
• 2 risk for pocket infection
• Usually occurs within 7 days of pacemaker
  insertion
• May have tenderness and redness over pacemaker
  site

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References

• Emedicine
• http//www.emedicine.com/emerg/topic805.htm
• Minish, Travis. Pacemaker Emergencies.
• http//www.cgi.ualberta.ca/emergency/rounds/files/
  pacers3.ppt
• The Implantable Pacemaker, a short historical
  overview.
• http//igitur-archive.library.uu.nl/dissertations/
  2006-0426-200006/c1.pdf
• Healthy Hearts
• http//www.healthyhearts.com/pacemaker.htm
• Medtronic
• http//www.medtronic.com/patients/heart.html
• Shelton State University
• http//www.sheltonstate.edu/userfiles/File/faculty
  /s20warren/NUR2020220EKG20Dysrrhythmias-Sinus,
  20Atrial,20Junctional,20Vent20.pdf
• Google Images
• http//images.google.com

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Thank You