Dysrhythmia Notes
Dysrhythmia Notes
Dysrhythmia Notes
WHAT IS DYSRHYTHMIA?
- is an abnormal or irregular heartbeat. If you have dysrhythmia, your heart
might beat too fast or too slowly. Or your heart's rhythm might be disrupted,
leading you to feel like your heart skipped a beat.
SA NODE
- generates an electrical signal that causes the atria to contract.
- Known as the “primary pacemaker of the heart”
- Located in the right upper corner of the right atrium
- It generates impulses for about 60-100 BPM
AV NODE
- It delays the impulses by 0.04 seconds to keep the ventricles from contracting
quickly.
- Located in the inferior right atrium near the coronary sinus
- It generates impulses for about 40-60 BPM
BUNDLE OF HIS
- is a group of fibers that carry electrical impulses through the center of
the heart. If these signals are blocked, you will have problems with your
heartbeat.
- It resumes the rapid conduction of impulses through the ventricles
- Divides into right and left bundle branches
PURKINJE FIBERS
- Extend from the bundle branches into the endocardium, deep into the
myocardial tissue. These fibers conduct impulses rapidly through the muscle
to assist in its depolarization and contraction.
- It generates impulses at a rate of 20-40 BPM
THE ECG COMPONENTS
P wave
- The first component of ECG waveform
- It represents atrial depolarization
- It precedes the QRS complex
- Amplitude: 2-3 mm high
- Duration: 0.06-0.12 second
- Configuration: usually rounded and upright
CLINICAL SIGNIFICANCE:
- Peaked or enlarged P waves may represent atrial hypertrophy or heart
enlargement associated with COPD, pulmonary emboli, valvular disease or
heart failure.
PR interval
- Tracks the atrial impulse from the atria through the AV node, bundle of his,
and right and left bundle branches.
- Changes in the PR interval indicate an alteration in the impulse delay as seen
in AV block.
- It is located from the beginning of the P wave to the beginning of the QRS
complex
- Duration: 0.12 - 0.20 second
CLINICAL SIGNIFICANCE:
- Prolonged PR intervals may represent delayed conduction through the atria or
AV junction due to heart block or ischemia.
QRS COMPLEX
- It represents ventricular depolarization.
- Immediately after the ventricles depolarize, they contract. This contraction
ejects blood from the ventricles and pumps it through the arteries, creating a
pulse.
- It follows the PR interval
- AMPLITUDE: 5 to 30 mm high
- DURATION: 0.06 to 0.10 second.
- Duration is measured from the beginning of the Q wave to the end of the S
wave
- CONFIGURATION : consists of the Q wave (the first negative deflection after
the P wave), the R wave (the first positive deflection after the P wave), and
the S wave (the first negative deflection after the R wave).
- The ventricles contracts rapidly minimizing contact time between the stylus
and ecg paper
ST segment
- Represents the end of ventricular depolarization and the beginning of
ventricular repolarization
- LOCATION: extends from the S wave to the beginning of the T wave
T wave
- represents ventricular repolarization
- LOCATION: follows the S wave
- CONFIGURATION: typically round and smooth
ECG INTERPRETATION:
SINUS TACHYCARDIA
- characterized by a sinus rate of more than 100 BPM.
- Atrial and Ventricular rhythms are regular, both rates are equal generally 100-
160 BPM.
- This can be seen in cases like hypovolemia, hemorrhage or pain.
SINUS BRADYCARDIA
- characterized by a sinus rate below 60 BPM but with regular rhythm
- CLINICAL SIGNIFICANCE: this may be caused by hyperkalemia, IICP,
hypothyroidism, hypothermia, sleep and glaucoma.
ATRIAL FLUTTER
- Is characterized by an atrial rate of 250-350 BPM, originating in a single atrial
focus. (has multiple p waves with regular space QRS)
- Resembles saw tooth appearance called “flutter waves” or “f waves”
- CLINICAL SIGNIFICANCE: Commonly found in patients with severe mitral
valve diseases, hyperthyroidism, pericardial and myocardial disease.
- IRRITABLE FOCUS - happens when the cells outside the sinus node start
generating electrical impulse automatically on their own.
ATRIAL FIBRILLATION
- The most common type of cardiac arrhythmia
- Electrical impulses are initiated randomly from many other sites called
“ectopic sites” These unsynchronized, chaotic impulses cause the atria to
quiver rather than to contract.
VENTRICULAR TACHYCARDIA
- Commonly called “V-tach”
- 3 or more consecutive PVC in a row and the ventricular rate exceeds 100
BPM.
- This arrhythmia may precede ventricular fibrillation and sudden cardiac death.
VENTRICULAR FIBRILLATION
- Commonly called “V-Fib”
- Is a chaotic pattern of electrical activity in the ventricles in which electrical
impulses arise from many different foci.