Critical Care Nursing

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What are the 4 primary activities of the cardiac cells?
- Automaticity
- Excitability
- Conductivity
- Contractility
The ability of cardiac muscle cells to generate their own electrical impulses spontaneously

Automaticity
Abilty of the cardiac cells to respond to an impulse

Excitability
Ability of the cardiac cells to receive an electrical impulse and transmit it to the other cardiac cells

Conductivity
Ability of the cardiac cells to contract

Contractility
The cardiac cycle is composed of what two activities?
- Electrical
- Mechanical
What activity is caused by automaticity?

Electrical
What activity is the contraction?

Mechanical
What are the 2 phases of the electrical activity?
- depolarization
- repolarization
What phase is depolarization?

Active phase
What phase is repolarization?

Resting phase
What are the 2 mechanical responses?
- Systole
- Diastole
During depolarization is it systole or diastole? Is it contraction or resting?
- Systole
- Contraction
During repolarization is it systole or diastole? Is it contraction or resting?
- Diastole
- Resting or filling
What happens before a mechanical activity?

Electrical activity
What is happening during ventricle repolarization?

The ventricles are filling with blood
Vulnerable phase (Twave) is when enough cells have repolarized that ____ ____ ________ will cause cells to depolarize leading to _______ ___________
- Any weak stimulus
- lethal arrhythmias
Under normal circumstances, depolarization is followed by what?

Contraction
Repolarization is the resting state in which the ventricles do what?

fill with blood
The ventricles need enough relaxation time in order for them to do what?

adequately fill before the next depolarization
How do you treat a slow heart rate?

Epinephrine
What is the conduction pathway?
- SA node
- Internodal tracts
- AV node
- Bundle of His
- Bundle branches
- Purkinje fibers
What is the pacemaker of the heart?

SA node (Sinoatrial node)
The SA node has how many beats/min?

60-100
The AV node has how many beats/min?

40-60
What are the functions of the AV node?
- Delays impulses into the ventricle
- The back up pacemaker
The bundle of His divides into what ?

The right bundle & left bundle
The left bundle divides into what?

Anterior fascicle and posterior fascicle
How many beats/min in the purkinje fibers?

15-40 bpm
What does the P wave represent?

Atrial depolarization
What is the normal measurement of a PR interval?

0.12 - 0.20
What is the normal measurement of a QRS interval?

0.04 - 0.10
What does the QRS complex represent?

Ventricular depolarization
What does the T wave represent?

Ventricular repolarization
A T wave inversion indicates what?

Myocardial ischemia
Changes in the ST segment indicates what?

Myocardial injury or ischemia
An elevated ST segment indicates what?

Myocardial injury, the action phase. The patient is having a heart attack
What are the steps to interpret an ECG?
- Determine regularity
- Determine heart rate
- Identify and examine the P waves
- Measure PR interval
- Measure QRS complex
- Name the rhythm
What is an abnormal cardiac rhythm

Dysrhythmia
What has an impact on the body's ability to maintain a normal hemodynamic status and adequate cardiac output?

dysrhythmia
What does a significant Q wave indicate?

MI
Q wave

first negative deflection
R wave

first positive deflections
S wave

negative deflection after R wave

Author

plbernal

172772

Card Set

Critical Care Nursing

Description

Conduction System and Introduction to Rhythm Analysis

Updated

2012-09-24T02:05:40Z