Cardiology Intensive Board Review, 3 ed.

Electrocardiographic Interpretation

Donald A. Underwood


General Features

1.Normal electrocardiogram (ECG)

2.Borderline ECG or normal variant (specify in other section)

3.Incorrect electrode placement

P-Wave Abnormalities

4.Right atrial abnormality

5.Left atrial abnormality

6.Nonspecific atrial abnormality

7.Sinoventricular condition with absent P wave

Supraventricular Rhythms

8.Normal sinus rhythm (without other abnormalities of rhythm or atrioventricular (AV) conduction)

9.Sinus rhythm (in presence of abnormality of rhythm or AV conduction)

10.Sinus arrhythmia

11.Sinus bradycardia

12.Sinus tachycardia

13.Sinus pause or arrest

14.Sinoatrial exit block

15.Ectopic atrial or junctional rhythm

16.Wandering atrial pacemaker

17.Atrial premature beats, normally conducted

18.Atrial premature beats, nonconducted

19.Atrial premature beats with aberrant intraventricular conduction

20.Atrial tachycardia (regular, sustained, 1:1 conduction)

21.Atrial tachycardia, repetitive (short paroxysms)

22.Atrial tachycardia, multifocal (chaotic atrial tachycardia)

23.Atrial tachycardia with AV block

24.Atrial flutter

25.Atrial fibrillation

26.Retrograde atrial activation

27.Supraventricular tachycardia, unspecified

Atrioventricular Junctional Rhythms

28.AV junctional premature beats

29.AV junctional escape beats or escape rhythm

30.AV junctional rhythm, accelerated rhythm (nonparoxysmal junctional tachycardia)

31.AV junctional tachycardia

Ventricular Rhythms

32.Ventricular premature beat(s), uniform, fixed coupled

33.Ventricular premature beats, R on T phenomenon

34.Premature ventricular contractions, in pairs

35.Ventricular parasystole

36.Ventricular tachycardia

37.Accelerated idioventricular rhythm

38.Ventricular escape beats or rhythm

39.Ventricular fibrillation

Atrioventricular Conduction Abnormalities

(Also see items 48 to 53)

40.AV block, primary

41.AV block, secondary—Mobitz type I (Wenkenbach)

42.AV block secondary—Mobitz type II

43.AV block, 2;1, 3:1, 4:1

44.AV block, complete

45.AV block, varying

46.Short PR interval (with sinus rhythm and normal QRS duration)

47.Preexcitation (Wolff-Parkinson-White) syndrome(s)

Atrial Ventricular Interactions in Arrhythmias

(Also see items 40 to 47)

48.Fusion beats

49.Reciprocal (echo) beats

50.Ventricular capture beats

51.AV dissociation (without complete AV block)

52.Isorhythmic AV dissociation

53.Ventriculophasic sinus arrhythmia

Abnormalities of QRS Voltage or Axis

54.Low voltage, limb leads only

55.Low voltage, limb and precordial leads

56.Left axis deviation (>30 degrees)

57.Right axis deviation (>+100 degrees)

58.Electrical alternans

Ventricular Hypertrophy

59.Left ventricular hypertrophy by voltage only

60.Left ventricular hypertrophy by left ventricular hypertrophy by voltage and ST-T segment (secondary repolarization changes)

61.Right ventricular hypertrophy

62.Combined ventricular hypertrophy

Intraventricular Conduction Disturbances

63.Right bundle branch block (RBBB), incomplete

64.RBBB, complete

65.Left anterior fascicular block

66.Left posterior fascicular block

67.Left bundle branch block (LBBB), complete with ST-T waves suggestive of acute myocardial injury or infarction

68.LBBB, complete

69.Intraventricular conduction disturbance, nonspecific type

70.Aberrant intraventricular conduction with supraventricular arrhythmia (specify rhythm)

Transmural Myocardial Infarction

(Also see items 88 and 89)

83.Probable ventricular aneurysm

ST-, T-, and U-Wave Changes

84.Subendocardial or subepicardial nontransmural infarction

85.Normal variant, early repolarization

86.Normal variant, juvenile T wave

87.Nonspecific ST- and/or T-wave changes

88.ST- and/or T-wave changes suggesting myocardial ischemia

89.ST- and/or T-wave changes suggesting myocardial injury

90.ST- and/or T-wave changes suggesting acute pericarditis

91.ST-T segment changes secondary to intraventricular conduction distribution or hypertrophy

92.Post extrasystolic T waves

93.Isolated J-point depression

94.Peaked T waves

95.Prolonged QT interval

96.Prominent U waves

Suggested Probable Clinical Disorder

97.Digitalis effect

98.Digitalis toxicity





103.Atrial septal defect, secundum

104.Atrial septal defect, primum

105.Dextrocardial, mirror image

106.Mitral valve disease

107.Chronic lung disease

108.Acute cor pulmonale including pulmonary embolus

109.Pericardial effusion

110.Acute pericarditis

111.Hypertrophic obstructive cardiomyopathy (idiopathic hypertrophic subaortic stenosis)

112.Hypertrophic obstructive cardiomyopathy; apical

113.Coronary artery disease

114.Central nervous system (CNS) disorder



117.Sick sinus syndrome

118.Cardiac transplant


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1.FIGURE 15.1: On this electrocardiogram, there is a sinus tachycardia. The voltage is low and in the V1 and II rhythm strips, electrical alternans can be seen. This is an ECG from a patient with cardiac tamponade. Electrocardiographic coding is 12, 58, and 109.

2.FIGURE 15.2: This electrocardiogram shows a sinus tachycardia. There is a generalized T-wave inversion. The T waves are symmetric, deep, and have a long QT interval. This is an electrocardiogram from a patient with a major CNS event such as a subarachnoid or intraventricular hemorrhage. Electrocardiographic coding would be 12, 95, and 114.

3.FIGURE 15.3: This electrocardiogram shows a sinus rhythm. There is prolongation of the QT interval. The T wave has a fairly normal duration and contour, however. This is an example of hypocalcemia. (Type III congenital long QT syndrome also has this appearance.) Electrocardiographic coding would be 8, 95, and 102.

4.FIGURE 15.4: On this electrocardiogram, there is a sinus rhythm. It is sinus bradycardia. There is a prolongation of the QT interval. In this case, there is ST-segment depression, T-wave flattening, and TU fusion with prominent U waves in the lateral precordial leads. This should suggest hypokalemia. Another possibility is digitalis plus an antiarrhythmic drug’s effects (such as quinidine or procainamide). Electrocardiographic coding would be 11, 96, and 100.

5.Figure 15.5: This patient has a sinus tachycardia. There is symmetry of the T waves and there is a degree of QT prolongation. This is an example of a mixed electrolyte abnormality, hyperkalemia, and hypocalcemia. Values at the time were potassium of 7.2 and calcium of 80. This would be coded 12, 94, 95, 99, and 102.

6.FIGURE 15.6: On this electrocardiogram, there is a narrow complex tachycardia. The complexes are regular. In lead V1, there is an atrial wave that has a short RP, long PR relationship. This is an example of supraventricular tachycardia or AV nodal reentrant tachycardia (AVNRT). If the atrial wave seen in V1 extends to 70 or 80 milliseconds out into the ST segment, then this type of tracing could be an example of AV reentrant tachycardia (AVRT), which usually involves a larger reentrant loop and a bypass tract. Electrocardiographic coding is 27.

7.FIGURE 15.7: Here there is a narrow complex tachycardia. It is chaotically irregular and there are multiple P-wave vectors. This is not atrial fibrillation, which also is chaotic, but instead is a multifocal atrial tachycardia. This patient also shows aberrancy in the 6th and 14th beats. Electrocardiographic interpretation is 22, 87, 70, and 107.

8.FIGURE 15.8: This patient has a regular rhythm, but the baseline as seen in lead V1 is chaotic. It is an example of atrial fibrillation with a regular ventricular response. This is actually an accelerated junctional rhythm most likely caused by digitalis excess. In lead V6 there is ST-segment sagging that is smooth and associated with QT interval shortening. This suggests digitalis “effect.” Digitalis effect is seen in the repolarization changes with ST-segment scooping. Digitalis “excess” is usually suggested by arrhythmias and in this case the accelerated junctional rhythm. The coding would be 25, 30, 97, and 98.

9.FIGURE 15.9: This patient shows an rSR′ pattern in lead V1 that might suggest a volume-overload right ventricular hypertrophy (RVH). That is supported in part by the right axis deviation. However, in looking at the rhythm strip in lead II, there is a basic sinus rhythm with a first-degree AV block and in addition there is a second atrial rhythm that is dissociated from the basic PQRS sequence. This is accessory atrial activity related to cardiac transplantation. This would be coded 9, 40, 57, 63, and 118.

10.FIGURE 15.10: On this electrocardiogram, there is a regular atrial activity, but the P waves are inverted in the inferior leads, suggesting an ectopic atrial tachycardia. This conducts with group beating and gradual PR prolongation. This is an example of atrial tachycardia with Mobitz type I AV block. This would be coded 23 and 41.

11.FIGURE 15.11: This electrocardiogram shows a sinus rhythm. There is a first-degree AV block and intermittent 2:1 block. In addition, there is ST-segment depression that is scooping in quality in the lateral leads. This is an example of digitalis excess with intermittent second-degree AV block and digitalis effect. It would be coded 11, 41 or 42, 97, and 98.

12.FIGURE 15.12: This patient has a right bundle branch block and left axis deviation. He also has pauses. In this case, the P waves are regular and the PR intervals do not change. This is an example of a Mobitz type II second-degree AV block. The P-wave vectors are prominent in both leads II and V1, suggesting left atrial enlargement. This would be coded 8, 42, 5, 56, and 64.

13.FIGURE 15.13: This patient has a right bundle branch block. There is also left axis deviation which probably is enough to qualify as an anterior hemiblock. There are occasional pauses. In this case, the pauses are preceded by P waves, which are within the preceding T waves, and so this is an example of blocked PACs and not an example of more advanced AV block associated with bifascicular block. This would be coded 11, 18, 56, 64, and 65.

14.FIGURE 15.14: This patient shows a sinus rhythm with a 2:1 AV block. This can either be a Mobitz type I or II AV block. It is impossible to tell which. This also shows ST-segment elevation with Q waves in the inferior leads with reciprocal changes in leads I and aVL and is an example of an acute inferior infarction with 2:1 AV block. This would be coded 8, 43, and 79.

15.FIGURE 15.15: This patient shows a sinus rhythm. There is ST elevation in the inferior leads, especially leads III and aVF. There are reciprocal depressions in leads I and aVL. In leads V1 and V2, there is also ST elevation. This is an acute inferior infarction plus acute right ventricular infarct. This would be coded 8 and 79. At least on this code sheet, the ability to call right ventricular infarction would not be available to you.

16.FIGURE 15.16: This electrocardiogram has a sinus rhythm. There are lateral T-wave changes that are not specific, and there are QS waves in leads V1 through V3. This is an anteroseptal infarction of uncertain age. It would be coded 8, 76, and 87.

17.FIGURE 15.17: Here, there is a normal sinus rhythm and marked left axis deviation. There are small Q waves in leads I and aVL with a slight activation delay in aVL. This is anterior hemiblock. Anterior hemiblock produces small Q waves in the right precordial leads. The QRS pattern seen in V2 is often very suggestive of anteroseptal infarction, but the specificity is much less in the presence of anterior fascicular block. This would be coded 8 and 65.

18.FIGURE 15.18: In this patient, there are symmetric, prominent T waves that are upright. These are seen in the inferolateral leads and are associated with ST depression in leads V1, V2, and V3. There are no Q waves so this is not an acute infarct, but it is an acute current of injury. The rhythm is sinus. Electrocardiographic coding would be 8 and 89.

19.FIGURE 15.19: On this electrocardiogram, there is a sinus rhythm. It is slow so sinus bradycardia. There are significant inferior Q waves and also Q waves in leads V5 and V6. There is also a prominent R-wave vector in lead V1, and the T waves are upright despite the presence of a right bundle branch block. Usually with a right bundle branch block, ST-segment and T-wave inversion are expected. In this case, the upright T wave is an example of a “primary” T wave. A prominent initial vector and upright T wave in V1, associated with inferior and lateral Q waves, are interpreted as an inferoposterior and lateral infarct. Electrocardiographic coding is 11, 80, 82, 78, and 64.

20.FIGURE 15.20: This electrocardiogram has a sinus rhythm. There is a prominent initial vector in lead V1 that is greater than the S wave. T wave is upright. This is compatible with posterior infarct. That is supported by the presence of pathologic Q waves in leads III and aVF. Electrocardiographic coding would be 8, 80, and 82.

21.Figure 15.21: This electrocardiogram shows a sinus rhythm. There are inferior Q waves and prominent R vector in leads V1 and V2. This might suggest inferoposterior infarction, but in leads V3 and V4, especially there is a short PR interval and a delta wave suggesting that this is preexcitation or Wolff-Parkinson-White syndrome. Electrocardiographic coding would be 8 and 47.

22.FIGURE 15.22: This patient has a sinus rhythm. Lead II does suggest left atrial enlargement with a P wave that is broad and notched. There is an rSR′ pattern in lead V1 with T-wave inversion and R′ greater than S. This type of pattern is commonly seen in volume-overload-type RVH. Volume-overload RVH and left axis should suggest ostium primum ASD. Usually an ASD will not affect P waves greatly, at least in the early phases of the process. Ostium primum ASDs, however, very often have mitral valve and notable mitral insufficiency plus left atrial enlargement. Electrocardiographic coding would be 8, 5, 63, 61, 56, and 104.

23.FIGURE 15.23: This electrocardiogram shows a sinus rhythm. There was a very prominent vector in lead V1 associated with upright T waves. This drops down to a more typical appearance in lead V2. This is not an example of posterior infarction but instead is an example of switched leads, V1 and V5 having been transposed. There is also ST-segment elevation throughout and perhaps some PR-segment elevation in aVR. This suggests acute pericarditis. Electrocardiographic coding would be 8, 3, and 90.

24.FIGURE 15.24: This patient has a wide complex tachycardia. There is AV dissociation and there is anterior, positive concordance in the chest leads. This is ventricular tachycardia. Electrocardiographic coding would be 9, 51, and 36.

25.FIGURE 15.25: This patient has marked right axis deviation and loss of voltage across the precordium. The P waves are inverted in leads I and aVL. Inverted P waves in leads I and aVL (if it is not an ectopic atrial rhythm) are caused by either dextrocardial or switched arm wires. Loss of voltage across the precordium suggests that this is dextrocardia. Electrocardiographic coding would be 8 and 105.

26.FIGURE 15.26: This patient has a sinus rhythm and right axis deviation. The vectors in leads I and aVL are incompatible with those seen in the other lateral leads, V5 and V6. The discrepancies are explained by the inverted P waves in leads I and aVL, which suggest switched arm wires. This is a normal ECG with a technical error. This would be coded 8 and 3.

27.FIGURE 15.27: The patient is a 6-year-old with an outflow tract murmur. Rhythm is sinus with a narrow complex. V1 shows small rSR′ with a large R′. There is right axis deviation. This is right ventricular hypertrophy. It is a volume-overload-type pattern. Most likely an ostium secundum ASD. Coded 8, 57, 61, and 103.

28.FIGURE 15.28: Here there is sinus bradycardia with left ventricular hypertrophy (voltage) and secondary T-wave changes extending into the right precordium. Most likely this is a hypertrophic cardiomyopathy with apical hypertrophy. This is occasionally called Yamaguchi syndrome after the initial describer of the variant. Coded 11, 60, and 112.

29.FIGURE 15.29: Although leads I, aVL, and III might suggest an atrial tachycardia, other leads clearly show a sinus rhythm. This is a motion artifact due to unilateral tremor and Parkinson disease. Coded 8 and 87.

30.FIGURE 15.30: Here is a sinus rhythm with minor lateral T-wave flattening. The last beat is premature and is an aberrant PAC. Characteristics of aberrancy are preceding atrial activity (seen in the T wave) and initial narrow vector with broadening toward the end of the complex and often a right bundle branch block type of pattern. Coded 8, 19, and 87.

31.FIGURE 15.31: This shows a sinus rhythm with first-degree AV block, generalized broadening of the QRS (with a right bundle branch block-like pattern), and symmetric broadening of the T wave. This is hyperkalemia. Potassium at the time was 6.2 mEq/L. Coded 8, 64, and 99.

32.FIGURE 15.32: Here is a sinus bradycardia with a sinus arrhythmia. There is terminally a symmetric T-wave inversion in leads V2 and V3 plus a qrS pattern in V3. This is an anteroseptal infarct of uncertain age. Also there are lateral T-wave changes that are not specific. Coded 11, 76, 87, and 113.

33.FIGURE 15.33: Rhythm is sinus with a first-degree AV block. There was a wide complex without septal Q waves in leads I and V6 (a left bundle branch block pattern) and left axis deviation. ST and T waves are “discordant” in the anterolateral leads (and also generally). There is also PR-segment elevation in lead aVR. This could be anterior “injury,” but more suggests acute pericarditis. Coded 8, 40, 56, 68, and 90.

34.FIGURE 15.34: There is a sinus rhythm with ST-segment elevation in lead aVL and reciprocal changes in the inferior and lateral leads. This is an acute high lateral infarct. Coded 8, 77, and 113.

35.FIGURE 15.35: A sinus rhythm with AV dissociation (complete heart block) and junctional escape. V1 shows an incomplete right bundle branch block pattern. T waves are not entirely normal in V3. Coded 12, 44, 63, and 87.


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