ECG

Question 1

NORMAL ECG
ECG Waves

Waves are positive or negative deflections from baseline.

1. There are four waveforms:
2. ________ are the time between two specific ECG events

Answer 1

P wave, QRS complex, T and U.
Intervals

Question 2

1. ______ is the first _______ deflection in the ECG, produced by atrial depolarization of both atria.
   It also represents the simultaneous contraction of the atria.

The height is less because of _______ muscle mass and dome shape is due to the _______ nature of depolarization of atrial muscle.

Answer 2

1. P wave, positive
2. less atrial muscle, slow

Question 3

1. Measured from the start at the P wave and the beginning of the QRS complex
2. It is _________ (i.e., increased
   conduction velocity through AV node)
   by stimulation of the ______ nervous system.
3. It is ______ (i.e., decreased
   conduction velocity through AV node)
   by stimulation of the ______ nervous system

Answer 3

1. PR Interval
2. Decreased, sympathetic
3. increased, parasympathetic

Question 4

1. Abnormal prolongation of the AV conduction time is called a ______ AV block.
2. The conduction pattern in which only a fraction of the atrial impulses are conducted to the ventricles is called a ________ AV block.

Answer 4

1. first-degree
2. second-degree

Question 5

The conduction pattern in which none of
the atrial impulses reaches the ventricles is called a _______, or _____ AV block.

Answer 5

third-degree, complete

Question 6

1. This consists of Q, R, and S waves
   and consists of deflections produced by ventricular depolarization.
2. _______ is the wave of depolarization passes along the bundle branches, and Purkinje fibers to first excite the interventricular septum, which depolarizes from ______ to ______.

Answer 6

1. QRS Complex
2. Q wave, left to right

Question 7

QRS COMPLEX

1._______ is the wave of depolarization that spreads from the subendocardial muscle layer to the subepicardial muscle layer and is the largest wave in ECG because of the ______ muscle mass of ventricles.

2. The sharpness of the wave represents the _____ of depolarization.

Answer 7

1. R Wave, greater
2. rapidity

Question 8

QRS COMPLEX

1. _______ is a small, _______ and sharp wave representing the depolarization of the posterobasal portion of the left ventricle and the pulmonary conus.

Answer 8

1. S Wave, negative

Question 9

1. Measured from the beginning of the Q wave (or R wave if Q wave is absent) to the J point.
2. This represents _______ depolarization.
3. Atrial _______ also occurs in this
   period.

Answer 9

1. QRS Interval (QRS Duration)
2. ventricular
3. repolarization

Question 10

________ is the positive deflection produced by ventricular ________.

Answer 10

T wave, repolarization

Question 11

1. Measured from the beginning of the QRS complex to the end of the T
   wave.
2. Represents ventricular
   depolarization and ventricular
   repolarization, corresponding to the duration of ________.

Answer 11

1. QT Interval
2. electrical systole

Question 12

1.Lies between the end of the QRS complex (J point) and the beginning of the T wave.

2. Elevation or depression of the J point suggests _________ or infarction

Answer 12

1. ST Segment
2. myocardial ischemia

Question 13

Interval measured between either the peak or the beginning of two successive P waves.

2. Is measured for calculation of the _______ rate .

Answer 13

1. PP Interval
2. atrial rate

Question 14

1. is measured between the peaks of two successive R waves.
2. Is measured for calculating the
   heart rate (the ________ rate)

Answer 14

1. RR Interval
2. ventricular

Question 15

1.
Thought to represent papillary muscle repolarization.

2. is rarely seen normally but becomes
   prominent in ________

Answer 15

1. U wave
2. hypokalemia

Question 16

Systematic Interpretation of ECG
Heart Rate

1. Heart rate < 60/min is called _______ while heart rate > 100/min is called _______.
2. The “_______” prefix can be attached to indicate that the rate is established by the ________

Answer 16

1. bradycardia, tachycardia
2. sinus, SA Node

Question 17

1. It is observed by calculating the successive cycle length (RR intervals).
2. Abnormalities of cardiac rhythm are called _________
   and can originate from virtually any part of the myocardium.

Answer 17

1. Cardiac Rhythm
2. arrhythmia