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553 - Monitoring & CV Patient > Exam 5 - Pacemakers > Flashcards

Exam 5 - Pacemakers Flashcards

1
Q

Pacemakers

A
  • Inserted into RA and/or RV
  • Can sense and stimulate electrical activity
  • Can be programmed externally
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2
Q

Pacemaker uses

A
  • Can be used to “overdrive” tachycardias
    - need cardioversion available as backup
  • 3rd degree av block
  • lesser degree av block/bradycardia
  • AV blocks +/- BBBs
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3
Q

J.A. McWilliam

A
  • 1899

- Zapping heart with electrical stimuli can cause heart to contract

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4
Q

Dr. William Weirich

A
  • 1957
  • used myocardial electrodes to restore HR, CO, and MAP in animals
  • allowed open heart surgery to expand dramatically
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5
Q

Arne Larson

A
  • 1958
  • Swedish patient who got 26 pacemakers in his life
  • Problem with early pacemakers was mercury batteries
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6
Q

Lithium iodide batteries

A
  • Revolutionized pacemakers
  • 1971
  • more reliable and lasted longer
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7
Q

Pacemaker components

A
  • generator (holds battery, electronics, and header)
    - can be MRI safe (titanium) or MRI bad
  • leads: unipolar (talks to generator) or bipolar (talks to lead itself)
    • attached to inside heart muscle passively (hook) or actively (screw)
    • unipolar more sensitive but bipolar less affected by muscle movement and magnetic fields
  • electrode tip
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8
Q

Temporary pacemaker types

A
  • transcutaneous: emergency use w/ external pacing/defib unit
  • transvenous: emergency use w/ external pacemaker
  • epicardial: wires sutured to RA (exit R of sternum) and RV (exit L of sternum)
  • used for short periods of time
  • In CPB…placed post x-clamp removal….before CPB termination
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9
Q

Single chamber permanent pacemaker

A
  • One lead into either RA or RV

- Used to fix slow/irregular heartbeat caused by heart block

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10
Q

Dual chamber pacemaker

A
  • One lead in A….one in V
  • Can create the atrial kick like in normal heart beat
  • leads to good CO
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11
Q

Triple chamber pacemaker

A
  • aka Bi-ventricular
  • aka Cardiac resynchrinization therapy (CRT)
  • Used on very sick hearts
  • lead in RA, RV, LV (via coronary sinus)
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12
Q

Demand pacemaker

A
  • fixes slow or irregular heart beats
  • senses when no electrical activity is detected…. and fires
  • after each detected native beat…timer resets
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13
Q

Fixed rate pacemaker

A
  • discharge at steady rate regardless of native heart activity
  • can lead to competition of native and pacemaker beats are too similar
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14
Q

Rate-responsive pacemaker

A
  • adjust pacing to patients level of physical activity
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15
Q

Implantable cardiac defibrillators

A
  • ICDs
  • when tachycardia is sensed…it shocks heart back into normal rhythm
  • very sophisticated algorithms
  • can also help w/ bradycardia, do low energy cardioversion, high energy defibrillation
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16
Q

Defibrillation

A
  • enough energy to cause all cardiomyocytes to contract
  • stops the cells and arrhythmias
  • forces all cells to enter refractory phase at same time
  • hopefully puts heart back in normal rhythm
17
Q

AC defib

A
  • no longer used
  • difficult to control
  • low conversion rate
  • only good on ventricular arrhythmias
  • causes voltage drops in hospital
18
Q

DC defib

A
  • 1962 by Dr. Bernard Lown
  • electrical charge is stored rather than delivered
  • need high voltage over short time span to be effective
  • defib in v-tach or v-fib
19
Q

Cardioversion

A
  • special shock 30 ms after r wave
  • done with algorithm
  • fixes a-fib, a-flutter, a-tach, SVTs
20
Q

Pacemaker nomenclature

A 
- Paced - Sensed - Response - (adaptive?)
A = atria
V = ventricle
D = dual
O = none
S = single
T = trigger
I = inhibit
R = responsive to physical activity
21
Q

5th letter

A
  • if present
  • response to tachyarrhythmias
    P = pacing response
    S = shock response
    D = dual
    O = no response
22
Q

Failure to capture

A
  • pacer spike…but no cardiac response
23
Q

Failure to pace

A
  • no pacer spike but should be
24
Q

Failure to sense

A
  • pacer fires randomly during cardiac cycle
25
Q

Pacer problems that can be fixed w/ reprogramming

A
  • Under-sensing: cant detect cardiac activity
  • Over-sensing: detecting muscle movement as cardiac activity
  • Loss of capture: pacer stimulation fails to make a heartbeat
  • crosstalk: when dual chamber device interprets atrial output as vent output
  • Pacemaker-sustained endless loop arrhythmia: tachycardia sustained by pacemaker

553 - Monitoring & CV Patient (10 decks)

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