Chapter 31: Concepts of Care for Patients with Dysrhythmias
- dysrhythmias: abnormal rhythms of the heart’s electrical system; affects
its ability to pump oxygenated blood throughout the body.
- causes include CAS, electrolyte imbalances, impaired gas exchange, and
drug toxicity.
- most often occur in older adults.
Myocardial Cells
- specialized myocardial cells regulate HR and rhythm.
- possess unique properties: automaticity, excitability, conductivity, and contractility.
- automaticity (pacing) = cells can generate an impulse spontaneously and repetitively.
normally only SA node can, but under ischemia/death cardiac cells can.
- excitability = heart cells are able to respond to an impulse that begins in pacemaker cells.
- conductivity = able to send a stimulus from one cell membrane to another.
- contractility = atrial/ventricular cells can shorten their length in response to stimulation.
mechanical activity of the heart.
Cardiac Cycle
depolarization = contraction = systole
repolarization = relaxing/refilling = diastole
Electrocardiography (ECG)
= picture of cardiac electrical activity.
- electrode placement is the same for males and females.
- standard 12-lead ECG = 6 leads are placed on the extremities, other 6 are on the chest.
R arm is always negative, L leg is always positive.
- right-sided ECG uses 18 leads to view R side of the heart.
- patient needs to be as still as possible when obtaining ECG.
- remove any excess hair before placing electrodes.
- small block = 0.04 seconds, large block = 0.20 sec, 5 large = 1 sec, 30 large = 6 sec.
ECG Components
- complexes: P wave, QRS complex, T wave, possible U wave.
- segments: PR segment, ST segment, TP segment.
- intervals: PR interval, QRS duration, QT interval.
- P wave = atrial depolarization – can be positive, negative, or both.
- PR segment = line from end of P wave to beginning of QRS complex, impulse is traveling through AV
node.
- PR interval = beginning of P wave to end of PR segment, delay of AV node to allow ventricles to fill.
- QRS complex = ventricular depolarization.
- ST segment = beginning of ventricular repolarization, length varies.
- T wave = ventricular repolarization, usually positive and rounded.
- U wave = late ventricular repolarization.
- QT interval = total time for both ventricular de and repolarization.
*artifact is interference, can look like a fuzzy baseline = caused by movement, loose electrodes…
ECG Analysis
1. determine HR count # of QRS complexes in 6 seconds and x by 10.
2. determine rhythm assess regularity amongst each interval.
3. analyze P waves check consistency, determine P wave before each QRS complex.
This study source was downloaded by 100000899527527 from CourseHero.com on 07-07-2025 09:50:34 GMT -05:00
https://www.coursehero.com/file/243495235/Dysrhythmiasdocx/
- dysrhythmias: abnormal rhythms of the heart’s electrical system; affects
its ability to pump oxygenated blood throughout the body.
- causes include CAS, electrolyte imbalances, impaired gas exchange, and
drug toxicity.
- most often occur in older adults.
Myocardial Cells
- specialized myocardial cells regulate HR and rhythm.
- possess unique properties: automaticity, excitability, conductivity, and contractility.
- automaticity (pacing) = cells can generate an impulse spontaneously and repetitively.
normally only SA node can, but under ischemia/death cardiac cells can.
- excitability = heart cells are able to respond to an impulse that begins in pacemaker cells.
- conductivity = able to send a stimulus from one cell membrane to another.
- contractility = atrial/ventricular cells can shorten their length in response to stimulation.
mechanical activity of the heart.
Cardiac Cycle
depolarization = contraction = systole
repolarization = relaxing/refilling = diastole
Electrocardiography (ECG)
= picture of cardiac electrical activity.
- electrode placement is the same for males and females.
- standard 12-lead ECG = 6 leads are placed on the extremities, other 6 are on the chest.
R arm is always negative, L leg is always positive.
- right-sided ECG uses 18 leads to view R side of the heart.
- patient needs to be as still as possible when obtaining ECG.
- remove any excess hair before placing electrodes.
- small block = 0.04 seconds, large block = 0.20 sec, 5 large = 1 sec, 30 large = 6 sec.
ECG Components
- complexes: P wave, QRS complex, T wave, possible U wave.
- segments: PR segment, ST segment, TP segment.
- intervals: PR interval, QRS duration, QT interval.
- P wave = atrial depolarization – can be positive, negative, or both.
- PR segment = line from end of P wave to beginning of QRS complex, impulse is traveling through AV
node.
- PR interval = beginning of P wave to end of PR segment, delay of AV node to allow ventricles to fill.
- QRS complex = ventricular depolarization.
- ST segment = beginning of ventricular repolarization, length varies.
- T wave = ventricular repolarization, usually positive and rounded.
- U wave = late ventricular repolarization.
- QT interval = total time for both ventricular de and repolarization.
*artifact is interference, can look like a fuzzy baseline = caused by movement, loose electrodes…
ECG Analysis
1. determine HR count # of QRS complexes in 6 seconds and x by 10.
2. determine rhythm assess regularity amongst each interval.
3. analyze P waves check consistency, determine P wave before each QRS complex.
This study source was downloaded by 100000899527527 from CourseHero.com on 07-07-2025 09:50:34 GMT -05:00
https://www.coursehero.com/file/243495235/Dysrhythmiasdocx/
