ECG made easy; chapter 2: Basic Echo

_____ is the ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse without being stimulated from another source, such as a nerve. a. Excitability b. Conductivity c. Automaticity d. Contractility

ANS: C The ability of cardiac pacemaker cells to create an electrical impulse without being stimulated from another source is called automaticity. Excitability is the heart muscles' ability to respond to impulse or stimulus. Conductivity is the ability of the cardiac cells to receive and transmit an electrical impulse. Contractility is the contraction of the heart muscle which produces the heartbeat.

On the ECG, the T wave represents _____. a. atrial contraction b. atrial repolarization c. ventricular contraction d. ventricular repolarization

ANS: D Ventricular repolarization is represented on the ECG by the T wave.

Which of the following correctly reflects examples of ectopic (latent) pacemakers? a. The SA node and AV junction b. The AV junction and ventricles c. The SA node and right bundle branch d. The AV junction and left bundle branch

b. The AV junction and ventricles

Tall, peaked T waves observed on the ECG are most commonly seen in patients with _____. a. hypokalemia b. hyperkalemia c. hyponatremia d. hypernatremia

b. hyperkalemia

Leads II, III, and aVF view the _____ surface of the left ventricle. a. anterior b. inferior c. septal d. lateral

b. inferior

Lead II records the difference in electrical potential between the _____ leg and _____ arm. a. left; left b. left; right c. right; left d. right; right

b. left; right

The normal pacemaker of the heart is the _____ node, which is found in the _____ atrium, and has an intrinsic firing rate of _____ beats/min. a. sinoatrial; left; 40 to 60 b. sinoatrial; right; 60 to 100 c. atrioventricular; left; 20 to 40 d. atrioventricular; right; 100 to 180

b. sinoatrial; right; 60 to 100

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. a. AV node b. SA node c. Purkinje fibers d. atrial pacemaker cells

c. Purkinje fibers

When the cardiac muscle cell is stimulated, the cell is said to _____. a. polarize b. recover c. depolarize d. repolarize

c. depolarize

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. a. atrioventricular (AV) node b. atria c. sinoatrial (SA) node d. right and left bundle branches

d right and left bundle branches

The PR interval is considered prolonged if it is more than _____ seconds in duration. a. 0.06 b. 0.12 c. 0.18 d. 0.20

d. 0.20

How do you determine whether the atrial rhythm on an ECG tracing is regular or irregular? a. Compare QT intervals. b. Compare PR intervals. c. Compare R to R intervals. d. Compare P to P intervals.

d. Compare P to P intervals.

_____ 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. a. Irritability b. Conductivity c. Polarization d. Refractoriness

d. Refractoriness

Which part of the conduction system receives an impulse from the bundle of His and relays it to the Purkinje fibers? a. SA node b. AV node c. Right and left atria d. Right and left bundle branches

d. Right and left bundle branches

What does the QRS complex represent? a. Atrial depolarization b. Ventricular contraction c. Ventricular repolarization d. Ventricular depolarization

d. Ventricular depolarization

The period during the cardiac cycle when cells cannot respond to a stimulus, no matter how strong, is called the _____ period. a. depolarized b. supranormal c. relative refractory d. absolute refractory

d. absolute refractory

Leads I, aVL, V5, and V6 view the _____ surface of the left ventricle. a. anterior b. septal c. inferior d. lateral

d. lateral

On the ECG, the P wave represents atrial _____ and the QRS complex represents ventricular _____. a. depolarization; depolarization b. repolarization; repolarization c. repolarization; depolarization d. depolarization; repolarization

depolarization; depolarization

The portion of the ECG tracing between the QRS complex and the T wave is called the ____. a. PR segment b. ST segment c. TP segment d. QT interval

b. ST segment

Which of the following is the first positive deflection seen on the ECG after the P wave? a. Q wave b. R wave c. S wave d. T wave

b. R wave

The intrinsic rate of the Purkinje fibers is _____ beats/min. a. 20 to 40 b. 40 to 60 c. 60 to 100 d. 100 to 180

a. 20 to 40

On an ECG, what is the first negative deflection seen after the P wave? a. Q wave b. R wave c. S wave d. T wave

a. Q wave

The QT interval is measured from the beginning of the _____. a. QRS complex to the end of the T wave b. P wave to the end of the QRS complex c. QRS complex to the beginning of the T wave d. P wave to the beginning of the QRS complex

a. QRS complex to the end of the T wave

In most patients, the sinoatrial (SA) and atrioventricular (AV) nodes are supplied by the _____ coronary artery. a. right b. left main c. circumflex d. left anterior descending

a. right

In an adult, the normal duration of the QRS complex is _____. a. 0.12 to 0.20 second b. 0.10 second or less c. 0.04 to 0.14 second d. 0.20 second or less

b. 0.10 second or less

The intrinsic rate of the atrioventricular (AV) bundle is _____ beats/min. a. 20 to 40 b. 40 to 60 c. 60 to 80 d. 80 to 100

b. 40 to 60

The intrinsic rate of the SA node is _____ beats/min. a. 40 to 60 b. 60 to 100 c. 100 to 180 d. 200 to 260

b. 60 to 100

_____ 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. a. Pacemaker b. Myocardial c. Specialized d. Electrical

b. Myocardial

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 _____. a. TP segment b. PR segment c. QT interval d. QRS duration

b. PR segment

The absolute refractory period begins with the onset of the _____ and terminates _____. a. P wave; with the end of the QRS complex b. QRS complex; at approximately the apex of the T wave c. QRS complex; with the end of the T wave d. P wave; with the beginning of the QRS complex

b. QRS complex; at approximately the apex of the T wave