Chapter 2 Flashcards
TRUE/FALSE
A conduction problem above the level of the bundle branches will largely affect the P wave and PR interval.
True
TRUE/FALSE
The period of time during the cardiac cycle when cells cannot respond to a stimulus, no matter how strong, is the relative refractory period.
false
TRUE/FALSE
Depolarization is the same as contraction.
false
TRUE/FALSE
In most ECG leads, a normal Q wave is less than 0.04 seconds in duration and less than one third the amplitude of the R wave in that lead.
true
TRUE/FALSE
The point where the QRS complex and the ST segment meet is called the ST junction or J-point.
true
TRUE/FALSE
If the wave of depolarization (electrical impulse) moves toward the positive electrode, the waveform recorded on ECG graph paper will be upright (positive deflection).
true
TRUE/FALSE
In the limb leads, the ST segment is normally isoelectric, or less than 1 mm above or below the isoelectric line.
true
In most patients, the sinoatrial (SA) and atrioventricular (AV) nodes are supplied by the _____ coronary artery.
right
The intrinsic rate of the atrioventricular (AV) bundle is _____ beats/min.
40 to 60
How do you determine whether the atrial rhythm on an ECG tracing is regular or irregular?
Compare P to P intervals.
_____ is the ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse without being stimulated from another source, such as a nerve.
Automaticity
In the heart’s conduction system, the _____ receive(s) an electrical impulse from the bundle of His and relay(s) it to the Purkinje fibers in the ventricular myocardium.
right and left bundle branches
In the heart’s conduction system, the _____ receive(s) an electrical impulse from the right and left bundle branches and relay(s) it to the ventricular myocardium.
Purkinje fibers
What does the QRS complex represent?
Ventricular depolarization
The normal pacemaker of the heart is the _____ node, which is found in the _____ atrium, and has an intrinsic firing rate of _____ beats/min.
sinoatrial; right; 60 to 100
On an ECG, what is the first negative deflection seen after the P wave?
Q wave
Lead II records the difference in electrical potential between the _____ leg and _____ arm.
left; right
Leads II, III, and aVF view the _____ surface of the left ventricle.
inferior
The period during the cardiac cycle when cells cannot respond to a stimulus, no matter how strong, is called the _____ period.
absolute refractory
Leads I, aVL, V5, and V6 view the _____ surface of the left ventricle.
lateral
The absolute refractory period begins with the onset of the _____ and terminates _____.
QRS complex;
at approximately the apex of the T wave
The QT interval is measured from the beginning of the _____.
QRS complex to the end of the T wave
In an adult, the normal duration of the QRS complex is _____.
0.10 seconds or less
The intrinsic rate of the Purkinje fibers is _____ beats/min.
20 to 40
The intrinsic rate of the SA node is _____ beats/min.
60 to 100
On the ECG, the T wave represents _____.
ventricular repolarization
On the ECG, the time necessary for the spread of an electrical impulse through the AV node, bundle of His, right and left bundle branches, and the Purkinje fibers is reflected by the _____.
PR segment
The portion of the ECG tracing between the QRS complex and the T wave is called the ____.
ST segment
Which of the following is the first positive deflection seen on the ECG after the P wave?
R wave
_____ cells are working cells of the heart that contain contractile filaments and form the muscular layer of the atrial walls and the thicker muscular layer of the ventricular walls.
Myocardial
When the cardiac muscle cell is stimulated, the cell is said to _____.
depolarize
On the ECG, the P wave represents atrial _____ and the QRS complex represents ventricular _____.
depolarization; depolarization
_____ is a term used to describe the period of recovery that cells need after being discharged before they are able to respond to a stimulus.
Refractoriness
Tall, peaked T waves observed on the ECG are most commonly seen in patients with _____.
hyperkalemia
Which part of the conduction system receives an impulse from the bundle of His and relays it to the Purkinje fibers?
Right and left bundle branches
Which of the following correctly reflects examples of ectopic (latent) pacemakers?
The AV junction and ventricles
The PR interval is considered prolonged if it is more than _____ seconds in duration.
0.20
_____ is the ability of cardiac cells to spontaneously initiate an electrical impulse without being stimulated from another source.
Automaticity
An ECG lead that has a positive and negative electrode is called a(n) _____ lead.
bipolar
The appearance of coved (“frowny face”) ST-segment elevation is called a(n) _____ _____ _____.
acute injury pattern
A line between waveforms is called a(n) _____.
segment
The cells of the heart that contain contractile filaments are called _____ cells.
myocardial
ECG changes observed in leads opposite the affected area of the heart; also called mirror image changes
Reciprocal changes
The QRS complex represents _____ depolarization.
Ventricular
Each electrode placed in a “V” position is a(n) _____ electrode.
Positive
Element or compound that breaks into charged particles (ions) when melted or dissolved in water or another solvent
Electrolyte
An ECG machine is a sophisticated _____.
Voltmeter
ECG changes observed in leads that look directly at the affected area of the heart
Indicative changes
The T wave represents ventricular _____.
Repolarization
The a in aVR, aVL, and aVF
Augmented
Impulse(s) originating from a source other than the SA node
Ectopic
The spread of an impulse through tissue already stimulated by that same impulse
Reentry
Height (voltage) of a waveform on the ECG
Amplitude
The P wave represents _____ depolarization.
Atrial
The stimulus that alters the electrical charges across the cell membrane may be electrical, mechanical, or _____.
Chemical
During this period, a weaker than normal stimulus can cause depolarization of cardiac cells.
Supranormal
Name the first positive deflection seen after the P wave on the ECG.
R wave
On the ECG, what do the ST segment and T wave represent?
On the ECG, the ST segment represents early ventricular repolarization and the T wave presents ventricular repolarization.
Explain the significance of Einthoven’s triangle.
Einthoven’s triangle is a means of illustrating that the two arms and the left leg form the apices of a triangle surrounding the heart. The two apices at the upper part of the triangle represent the points at which the two arms connect electrically with the fluids around the heart. The lower apex is the point at which the left leg connects with the fluids.
Generally speaking, what is the normal duration of a QT interval?
The duration of the QT interval varies according to age, gender, and particularly heart rate. If the QT interval is less than half the RR interval, it is probably normal.
List four major electrolytes that influence cardiac function.
Sodium, potassium, calcium, and chloride
Is depolarization the same as contraction? Explain your answer.
Depolarization is not the same as contraction. Depolarization (an electrical event) is expected to result in contraction (a mechanical event).
It is possible to see organized electrical activity on the cardiac monitor, yet evaluation of the patient reveals no palpable pulse. This clinical situation is called pulseless electrical activity (PEA).
