Standardization

Question 1

The fundamental frequency for the QRS complex at the body surface is ~___

Answer 1

10 Hz

Question 2

The fundamental frequency of T waves is approximately ____

Answer 2

1 to 2 Hz

Question 3

The 1975 AHA recommendations included a ___-Hz low-frequency cutoff for diagnostic electrocardiography

Answer 3

0.05

Question 4

The ANSI/AAMI standard of 1991, reaffirmed in 2001, recommended a high-frequency cutoff of at least ___Hz for all standard 12-lead ECGs

Answer 4

150

Question 5

Where do you place the chest leads

Answer 5

Six electrodes are placed on the chest in the following locations:
V1, fourth intercostal space at the right sternal border;
V2, fourth intercostal space at the left sternal border;
V3, midway between V2 and V4;
V4, fifth intercostal space in the midclavicular line;
V5, in the horizontal plane of V4 at the anterior axillary line, or if the ANTERIOR axillary line is ambiguous, midway between V4 and V6;
V6, in the horizontal plane of V4 at the MIDaxillary line.

The horizontal plane through V4 is preferable to the fifth intercostal interspace for the placement of V5 and V6 and should be used for placement of these electrodes.

Definition of V5 as midway between V4 and V6 is conducive to greater reproducibility than occurs for the anterior axillary line, and this should be used when the anterior axillary line is not well defined.

In the placement of V6, attention should be directed to the definition of the midaxillary line as extending along the middle, or central plane, of the thorax

Question 6

Effect on ECG tracing of superior misplacement of V1 and V2 in the second or third intercostal space

Answer 6

This can result in reduction of initial R-wave amplitude in these leads, approximating 0.1 mV per interspace, which can cause poor R-wave progression or erroneous signs of anterior infarction

Superior displacement of the V1 and V2 electrodes will often result in rSr complexes with T-wave inversion, resembling the complex in lead aVR.

Question 7

Lead I is defined as the potential difference between the _______, lead II is defined as the potential difference between the _____ , and lead III is defined as the potential difference between the _______

Answer 7

I- (LA-RA)
II- (LL-RA)
III-(LL-LA).

Question 8

Where do you place the posterior leads

Answer 8

Examination of additional posterior chest leads has been proposed for the identification of ST-elevation events in the posterior wall, including V7 (at the posterior axillary line), V8 (below the scapula), and V9 (at the paravertebral border), each in the same horizontal plane as V6

Question 9

the committee recommends that for the present, a QRS duration of greater than ___ms in subjects older than 16 years of age be regarded as abnorma

Answer 9

110

Question 9

Normal axis

Answer 9

-30 to 90

Question 10

Left axis deviation

Answer 10

Left-axis deviation is -30° and beyond.
Moderate left-axis deviation is between -30° and -45°.
Marked left-axis deviation is from -45° to -90° and is often associated with left anterior fascicular block.

Question 11

Marked right axis deviation

Answer 11

Moderate right-axis deviation in adults is from 90° to 120°, and marked right-axis deviation, which is often associated with left posterior fascicular block, is between 120° and 180°.

Question 12

Criteria for CRBBB

Answer 12

1. QRS duration greater than or equal to 120 ms in adults, greater than 100 ms in children ages 4 to 16 years, andgreater than 90 ms in children less than 4 years of age.
2. rsr’, rsR’, or rSR’ in leads V1 or V2. The R’ or r’ deflection is usually wider than the initial R wave. In a minority of patients, a wide and often notched R wave pattern may be seen in lead V1 and/or V2.
3. S wave of greater duration than R wave or greater than 40 ms in leads I and V6 in adults.
4. Normal R peak time in leads V5 and V6 but greater than 50 ms in lead V1.

Of the above criteria, the first 3 should be present to make the diagnosis.

When a pure dominant R wave with or without a notch is present in V1, criterion 4 should be satisfied.

Question 13

Criteria for CLBBB

Answer 13

1. QRS duration greater than or equal to 120 ms in adults, greater than 100 ms in children 4 to 16 years of age, and greater than 90 ms in children less than 4 years of age.
2. Broad notched or slurred R wave in leads I, aVL, V5, and V6 and an occasional RS pattern in V5 and V6 attributed to displaced transition of QRS complex.
3. Absent q waves in leads I, V5, and V6, but in the lead aVL, a narrow q wave may be present in the absence of myocardial pathology.
4. R peak time greater than 60 ms in leads V5 and V6 but normal in leads V1, V2, and V3, when small initial r waves can be discerned in the above leads.
5. ST and T waves usually opposite in direction to QRS.
6. Positive T wave in leads with upright QRS may be normal (positive concordance).
7. Depressed ST segment and/or negative T wave in leads with negative QRS (negative concordance) are abnormal (11,12) and are discussed in part VI of this statement.
8. The appearance of LBBB may change the mean QRS axis in the frontal plane to the right, to the left, or to a superior, in some cases in a rate-dependent manner

Question 14

Criteria for LAFB

Answer 14

1. Frontal plane axis between -45° and -90°.
2. qR pattern in lead aVL.
3. R-peak time in lead aVL of 45 ms or more.
4. QRS duration less than 120 ms.

These criteria do not apply to patients with congenital heart disease in whom left-axis deviation is present in infancy

Question 15

Criteria for LPFB

Answer 15

1. Frontal plane axis between 90° and 180° in adults. Owing to the more rightward axis in children up to 16 years of age, this criterion should only be applied to them when a distinct rightward change in axis is documented.
2. rS pattern in leads I and aVL.
3. qR pattern in leads III and aVF.
4. QRS duration less than 120 ms.

Question 16

Criteria for WPW

Answer 16

Whether preexcitation is full or not cannot be determined from the body surface ECG, but the following criteria are suggestive of full preexcitation:
1. PR interval (assuming no intra-atrial or interatrial conduction block) less than 120 ms during sinus rhythm in adults and less than 90 ms in children.
2. Slurring of initial portion of the QRS complex (delta wave), which either interrupts the P wave or arises immediately after its termination.
3. QRS duration greater than 120 ms in adults and greater than 90 ms in children.
4. Secondary ST and T wave changes.

Question 17

corresponds to the plateau phase of the ventricular transmembrane action potential.

Answer 17

ST segment

Question 18

absence of pronounced voltage gradients is similar to that which occurs during electric diastole, that is, from the end of repolarization to the onset of the next depolarization, when ventricular myocardial cells are at their resting transmembrane potential of approximately -85 mV. This corresponds to the ___ segment on the ECG

Answer 18

TP

Question 19

Ventricular gradient in a single ECG lead is the net time integral of the ECG voltage from the beginning of the __ wave to the end of the __ wave.

Answer 19

P

U

Question 20

ST- and T-wave amplitudes are referenced against which segment/s of the ECG

Answer 20

ST- and T-wave amplitudes are referenced against the TP or PR segments of the ECG.

Question 21

threshold for abnormal J point in V2 and v3
Men >= 40 yrs old
Men <40 yrs old
Women

Answer 21

The threshold value for abnormal J-point elevation in V2 and V3 recommended in that part is 0.2 mV for men 40 years of age and older and 0.25 mV for men less than 40 years of age. The recommended threshold value for adult women in V2 and V3 is 0.15 mV.

**The threshold recommended for abnormal J-point elevation for men and women in all other standard leads is 0.1

Question 22

Normal t wave amplitude of V2 in men vs in women

Answer 22

In normal adults, the T-wave amplitude is most positive in lead V2 or V3.

T-wave amplitudes for V2 from 1.0 to 1.4 mV have been listed as upper normal thresholds in men (up to 1.6 mV in the 18- to 29-year age group) and from 0.7 up to 1.0 mV in women.

Question 23

Definition of inverted t wave vs deep negative t wave vs giant negative t wave

Answer 23

As more quantitative descriptors, it is proposed that the T wave in leads I, II, aVL, and V2 to V6 be reported as inverted when the T-wave amplitude is from -0.1 to -0.5 mV, as deep negative when the amplitude is from -0.5 to -1.0 mV, and as giant negative when the amplitude is less than -1.0 mV

Question 24

Definition of low amplitude t wave vs flat t wave

Answer 24

In addition, the T wave may be called low when its amplitude is less than 10% of the R-wave amplitude in the same lead and as flat when the peak T-wave amplitude is between 0.1 and -0.1 mV in leads I, II, aVL (with an R wave taller than 0.3 mV), and V4 to V6.

Question 25

u wave is most evident in which leads

Answer 25

v2-v3

amplitude has been suggested to be approximately 0.33 mV or 11% of the T wave

Question 26

Effect of HR to u wave amplitude

Answer 26

bradycardia increases amplitude of u wave

Question 27

Which leads should you look at when measuring QT

Answer 27

When the QT interval is measured in individual leads, the lead showing the longest QT should be used (39). This is usually V2 or V3.

Question 28

If T and U wave cannot be separated, how will you measure QT ?

Answer 28

If the T wave and U wave are superimposed or cannot be separated, it is recommended that the QT be measured in the leads not showing U waves, often aVR and aVL (39), or that the downslope of the T wave be extended by drawing a tangent to the steepest proportion of the downslope until it crosses the TP segment.

Question 29

Formula for QTc

Answer 29

Question 30

Overall, the gender difference in rateadjusted QT interval becomes small after ___ years of age and practically disappears in older men and women.

Answer 30

40

Question 31

Definition of prolonged qtc

Answer 31

prolonged QT: women, 460 ms or longer; men, longer than 450 ms

Question 32

Definition of short qtc

Answer 32

short QT: women and men, 390 ms or shorter.

Question 33

The difference between the longest and shortest QT intervals is referred to as ______

Answer 33

QT dispersion.

Question 34

Adult women have a slightly lower upper limit of QRS voltage than men do, although ___ is the only measurement with a large difference

Answer 34

SV3

Question 35

Criteria that include the depth of the __ wave in left precordial leads improve detection of LVH in the presence of left anterior fascicular block

Answer 35

S

In left anterior fascicular block, the QRS vector shifts in a posterior and superior direction, resulting in larger R waves in leads I and aVL and smaller R waves but deeper S waves in leads V5 and V6. R-wave amplitude in leads I and aVL are not reliable criteria for LVH in this situation. Criteria that include the depth of the S wave in left precordial leads improve detection of LVH in the presence of left anterior fascicular block

Question 36

Definition of left atrial abnormality in lead II

Answer 36

P-wave duration (120 ms or more) and widely notched P wave (40 ms or more)

Question 37

Criteria for right atrial abnormality

Answer 37

A tall upright P wave in lead II (greater than 2.5 mm) is characteristic, often with a peaked or pointed appearance that presumably reflects summation of the enhanced right atrial component with the simultaneous left atrial component.

Prominent initial positivity of the P wave in V1 or V2 (1.5 mm [0.15 mV] or more) also indicates right atrial abnormality.

Question 38

threshold for abnormal J-point
elevation in V3R and V4R

Answer 38

Question 39

threshold value for abnormal Jpoint
elevation in V7 through V9

Answer 39

Question 40

For men and women of all ages, the threshold value for abnormal J-point depression

Answer 40

Question 41

When ST-segment elevation is present in I and aVL, as well as in leads V1 through V4 and sometimes in V6, and ST-segment depression is present in leads II, III, and aVF, the automated interpretation should suggest

Answer 41

an extensive anterior wall or anterobasal ischemia/infarction due to occlusion of the proximal portion of LAD

Question 42

When ST-segment elevation is present in leads V3 through V6, and ST-segment depression is not present in leads II, III, and aVF, the automated interpretation should suggest

Answer 42

anterior wall ischemia/infarction due to occlusion of the MID or DISTAL portion of the left anterior descending coronary artery

Question 43

When the RCA is occluded in its proximal portion, ischemia/infarction of the right ventricle may occur, which causes the spatial vector of the ST-segment shift to be directed to the right and anteriorly, as well as inferiorly. This will result in ST-segment elevation in leads placed on

Answer 43

the right anterior chest, in positions referred to as V3R and V4R, and often in lead V1

***Lead V4R is the most commonly used right-sided chest lead

**It is important to recognize that the ST elevation in the right-sided chest leads associated with right ventricular infarction persists for a much shorter period of time than the ST elevation connoting inferior wall infarction that occurs in the extremity leads. For this reason, leads V3R and V4R should be recorded as rapidly as possible after the onset of chest pain

The joint task force of the AHA and the American College of Cardiology, in collaboration with the Canadian Cardiovascular Society, has recommended that right-sided chest leads V3R and V4R be recorded in all patients presenting with ECG evidence of acute inferior wall ischemia/infarction

Question 44

ST-segment depression in leads V1, V2, and V3 that occurs in association with an inferior wall infarction may be caused by occlusion of either the RCA or the LCx. This ECG pattern has been termed _____

Answer 44

posterior or posterolateral ischemia

Question 45

When the resting ECG reveals ST-segment depression greater than 0.1 mV (1 mm) in 8 or more body surface leads coupled with ST-segment elevation in aVR and/or V1 but is otherwise unremarkable, the automated interpretation should suggest

Answer 45

ischemia due to multivessel or left main coronary artery obstruction.

Question 46

The specific pattern of deeply inverted T waves with QT prolongation in leads V2 through V4 should be interpreted as consistent with

Answer 46

severe stenosis of the proximal left anterior descending coronary artery or with a recent intracranial hemorrhage (CVA [cerebrovascular accident] pattern).