Waves/Intervals and Segments
Represents atrial depolarization, contraction of the atria
P Wave
a dysrhythmia characterized by a heart rate less than 60/min
Sinus Bradycardia
the complete absence of any waves on the EKG tracing
asystole.
normal rhythms that originate from the firing of the sinoatrial (SA) node and are characterized by the presence of one P wave for each QRS interval on the EKG
What is a “sinus rhythm”
Starts at the end of the S wave and ends at the beginning of the T wave. Represents the time from the end of ventricular depolarization to the beginning of ventricular repolarization.
ST Segment
Represents ventricular repolarization, relaxation of the ventricles
T Wave
a dysrhythmia with a heart rate greater than 100/min and one P wave preceding each QRS complex
Sinus Tachycardia
A cardiac test that records electrical activity of the heart, provides information about heart rate and rhythm, and can show evidence of a previous heart attack.
Electrocardiogram (EKG)
A regular, fast rhythm characterized by large, irregular, wide QRS complexes on the EKG.
Define ventricular tachycardia.
Represents ventricular depolarization, contraction of the ventricles. (Atrial repolarization is not visible but occurs during this phase.)
QRS Wave
Not always visible but represents a repolarization of the bundle of His and Purkinje fibers.
U Wave
Premature contractions in the ventricles
PVC (Premature Ventricular Contraction)
What is the duration of a standard calibration box
0.2 seconds
A break in the normal EKG is sinus arrest. In this condition, the SA node failed to fire; it is not significant unless the person experiences symptoms such as shortness of breath, fainting, or chest pain, or if the periods of arrest last longer than 6 seconds.
What characterizes a “sinus arrest”?
A type of abnormal heart rhythm in which ventricles twitch or quiver, not pumping blood to the rest of the body.
ventricular fibrillation.
Starts at the beginning of the P wave and ends at the beginning of the Q wave. Represents the time from the beginning of atrial depolarization to the beginning of ventricular depolarization.
PR Interval
there is rapid, disorganized firing of multiple sites within the atrial tissue. This results in lots of fibrillatory waves between QRS complexes. It also results in an irregular QRS rhythm (the distance is different between any two QRS complexes on the EKG). Patients who have atrial fibrillation are at increased risk of developing blood clots, making recognition of dysrhythmia extremely important. Blood thinners may be prescribed to decrease the risk of stroke.
Atrial Fibrillation
What is the height of a standard calibration box
10 mm
Alteration or interference on the EKG that is not related to cardiac electrical activity; appears as distorted lines or waves.
What is an “artifact”?
What are the three abnormal EKG rhythms that are emergent and need immediate intervention?
Ventricular tachycardia
Ventricular fibrillation
Asystole
Starts at the beginning of the Q wave and ends at the end of the T wave. Represents the time from the beginning of ventricular depolarization to the end of ventricular repolarization.
QT Interval
a single area within the atrial tissue is firing at a rate faster than the rate the ventricles are responding to. The result is multiple flutter waves for each QRS complex on the EKG. Atrial flutter can be treated with medication to control the rate.
Atrial Flutter
the instrument used to record the heart’s electrical activity
electrocardiograph
also known as arrhythmias, can arise when the SA node fires too slowly or too quickly. characterized by slight irregularity in the QRS complexes in an otherwise normal EKG. Sinus dysrhythmia is frequently seen in children and is caused by changes in vagal tone during normal breathing.
What is a “sinus dysrhythmia”?
occur when the atria are triggered to contract earlier than they should, resulting in a premature contraction.
PAC (Premature Atrial Contraction)