Chapter 10

Question 1

Electronic pacemakers

Answer 1

Artificial pacemakers, are devices that deliver an electrical impulse to the myocardium to cause the cells to depolarize. Provides small amount of electrical current in a predetermined interval to mimic the nl pacemaker of the heart.

Question 2

How do pacemakers affect the atria

Answer 2

It aids in reestablishing nl electrical conduction of impulses, correct dysrhythmias

Question 3

Standard rate of pacemakers

Answer 3

70-72 bpm

Question 4

Where is the pacemaker placed

Answer 4

Atria, ventricles or both

Question 5

Atrioventricular pacing

Answer 5

Provides direct stimulation of the atria and ventricles in a sequence patterns known as atrioventricular sequential pacing. It allows for an atrial kick. Used for pts with heart failure

Question 6

Atrial kick

Answer 6

Provides the extra blood supply needed for approximately 10-30% of the normal cardiac output

Question 7

Ventricular pacemaker

Answer 7

delivers direct stimulation to the ventricles and produces a ventricular contractions

Question 8

Atrial pacemaker

Answer 8

Used alone when the conduction system from the atrioventricular node through the ventricles is intact and functioning

Question 9

Evaluating Pacemaker Function

Answer 9

The most important aspect of care is to verity the effectiveness of the pacemaker and determine the presence of a pulse with each captured beat.

Question 10

How is a capture seen in an ECG?

Answer 10

Captures are represented by a pacing spike immediately prior to the waveform

Question 11

Pacing spike

Answer 11

Could be atria, ventricular, or both. It is an artifact indicating the stimulation of electrical current from the pacemaker generator. The current is a quick delivery and is reflected as a this pike followed by a P wave or a wide QRS complex or both.

Question 12

Atrial pacing

Answer 12

Pacing spike will be followed by a P wave.

Question 13

Ventricular pacing

Answer 13

Pacing spike will be followed by a wide QRS complex, which looks similar to a LBBB

Question 14

LBBB pattern

Answer 14

Rhythm has a P wave and the QRS complex measures 0.12 sec or greater. L ventricle takes longer than the R to depolarize because of its size

Question 15

AV Delay

Answer 15

Similar to the measurement of the PR interval on a nl rhythm tracing. Measured form the atrial spike to the ventricle spike.

Question 16

AV delay programmed time frame

Answer 16

Somewhere between 0.12 to 0.20 seconds

Question 17

Inherent rhythm

Answer 17

The pt’s own heart rhythm

Question 18

7 steps to evaluate a pacemaker rhythm

Answer 18

1. What are the rate and regularity of the paced rhythm? Paced spikes should be the same.
2. What are the rate and regularity of the intrinsic rhythm (the pt’s own rhythm)? The faster rate will control the rhythm.
3. Is the atrial lead sensing appropriate? (for AV sequential pacemakers only). Atrial spikes then P waves.
4. (for atrial, AV sequential, and atriobiventricular pacemakers) Is atrial capture present? Atrial spike then P wave. The P wave after indicates that the atrial capture occurred.
5. (for atrioventricular sequential and atriobiventribular pacemakers) Is atrioventricular delay appropriate? Atrioventricular delay is measured form the atrial spike to the ventricular spike, this should be the same as the rate set up for the pacemaker.
6. Is ventricular sensing appropriate? There needs to be a ventricular spikes with a wide QRS following.
7. Is ventricular capture present? Every ventricular spike should have a wide QRS complex after it.

Question 19

Most common pacemaker rate setting

Answer 19

70 bpm

Question 20

What battery to pacemakers use to create an impulse?

Answer 20

Lithium batteries

Question 21

What are complications of the pacemaker?`

Answer 21

When the batteries are dying and need to be replaced which can cause slower firing rates than set, less effective sensing capabilities, and lower electrical current than predetermined

Question 22

Gour pacemaker complications seen in the ECG

Answer 22

Malfunctioning
Malsensing
Loss of capture
Oversensing

Question 23

Malfunctioning (failure to pace)

Answer 23

Caused by pacemakers not sending electrical impulses to the myocardium. Pacemaker intervals are irregular and impulse slower than set rate. No spike is seen. Pt will experience hypotension, lightheadedness, and blackout periods

Question 24

Malsensisng (failure to sense)

Answer 24

Caused by pacemaker not sensing the pt’s own inherent rate. May send current to heart during relaxation phase; also known as pacemaker competition with the pt’s own heart. With atrial pacing, atrial fibrillation can occur; with ventricular pacing, ventricular tachycardia or ventricular fibrillation can occur.

Question 25

Loss of capture (failure to depolarize)

Answer 25

Pacing activity occurs, but myocardium is not depolarized. Pacing spikes will occur without capture waveform, such as P wave or QRS complex. Symptoms depend on the basic dysrhythmia and the pt’s condition prior to the pacemaker insertion.

Question 26

Oversensing

Answer 26

Pacemaker perceives electrical current from sources other than the heart. Either (1) the pt’s own heart rate is recorded and is slower than the set rate of the pacemaker or (2) the pacemaker spikes and captures at a slower rate than set. Pt may have signs and sx of low cardiac output.

Question 27

What is BBB?

Answer 27

Occurs when one or both of the ventricular pathways are damaged or delayed due to cardiac disease, drugs, or other conditions.

Question 28

What happens in the BBB?

Answer 28

When an area of one of the bundle branches is damaged, electrical current will not be able to travel through that tissue to reach the myocardial tissue in its usual fashion. Current will travel down the good bundle and will activate the myocardial tissue in that corresponding ventricle only. The other ventricle must then receive the impulse as current travels from one cell to the next until the entire myocardial contraction occurs.

Question 29

What condition is similar to knocking down of a line of dominoes where each domino represents a cardiac cell?

Answer 29

BBB. The cell will not contract until the next cell delivers the energy.

Question 30

How is the delay in ventricular contraction caused by BBB seen in an ECG?

Answer 30

A wider than nl QRS complex

Question 31

RBBB

Answer 31

Impulse wil travel down the conduction pathway normally until after the bundle of His. Current travels down the L bundle branch to activate the ventricles.

Question 32

LBBB

Answer 32

L conduction pathway is blocked. Current must travel down the R bundle branch to cause the R ventricle, the septum, then the L ventricle to contract.

Question 33

How do we identify a BBB?

Answer 33

The appearance of a wide QRS complex with other atrial dysrhythmia properties.

Question 34

How do we identify a RBBB?

Answer 34

Characteristics will be similar over monitoring leads I, II, and III as well as monitoring leads V1 and V6. QRS complex is positively deflected.

Question 35

How to distinguish between RBBB or LBBB?

Answer 35

Seen in the precordial leads, lead VI is preferred. In LBBB the QRS complex is negatively deflected.

Question 36

Signs and sx’s of BBB

Answer 36

Those of the basic rhythm. Ex: if the rhythm is sinus tachycardia with RBBB pt will have sx’s of fast hr. the BBB will further deteriorate the development of another bundle branch block, if the current becomes totally blocked and current cannot reach the myocardium, this is considered a complete heart block.

Question 37

Tx to BBB

Answer 37

Monitoring, observation for deterioration. If further deterioration occurs, a temporary pacemaker may be applied. Further complications can lead to code blue and application of a permanent pacemaker.