T Wave: Normal Variations and Flat T Wave

Abstract

Genesis of normal T wave and the reason for its being in the same direction as that of the preceding QRS are explained with the help of a diagram. Configuration of normal T wave is discussed in detail with representative electrocardiogram. Normal variations in the configuration of the T wave in different leads are discussed. Clinical significance of variations in amplitude of T wave in relation to the amplitude of the preceding QRS complex and the following U wave are discussed with representative electrocardiograms. Causes of flat T wave are discussed with representative electrocardiograms. Summary and MCQs at the end of the chapter help in quick revision and self-assessment.

Appendices

Summary

• T wave is produced by repolarization of the ventricular myocardium.

• Polarity is generally the same as the net polarity of the preceding QRS.

• It is smooth and rounded. Proximal limb is shallow. Distal limb is relatively sharp.

• Normally the T wave is positive in leads I, II, aVL, aVF, V₅, and V₆. It is inverted in lead aVR. In lead III it can be inverted. In leads V₁ and V₂ it can be inverted or biphasic (initially positive, terminally negative).

• Amplitude is generally less than 0.5 mV in limb leads and less than 1.5 mV in any precordial lead.

• Amplitude is greater than accompanying U wave, if any.

• T wave may be inverted in right precordial to mid precordial leads (V₁ to V₄) in young (specially in females)—Juvenile pattern.

• In early repolarization variant prominent biphasic T wave (initial positive, terminal negative) with mild elevation of the J point can be seen in precordial leads. T waves normalize during exercise.

• Diffuse flattening of the T waves can be seen in pericardial effusion, myxedema, hypokalemia, and Amiodarone therapy. Left ventricular systolic overload can produce flattening of T waves in leads I, aVL, V₅, and V₆.

MCQs

Q1. The T wave is produced by:

• (a) Atrial repolarization

• (b) Atrial depolarization

• (c) Ventricular depolarization

• (d) Ventricular repolarization

Q2. In a normal person the T wave can be inverted in:

• (a) Lead V₁

• (b) Lead III

• (c) Lead aVF

• (d) All

Q3. In normal persons, the T wave of lead aVR is:

• (a) Upright

• (b) Biphasic

• (c) Inverted

• (d) Any shape

Q4. T wave can be inverted in leads I and aVL in:

• (a) High lateral myocardial infarction

• (b) Dextrocardia

• (c) Technical dextrocardia

• (d) All

Q5. What is correct for a normal T wave?

• (a) Proximal limb is sloping

• (b) Apex is blunt

• (c) Distal limb is sloping

• (d) All

Q6. What suggests an abnormal T wave?

• (a) Pointed apex

• (b) Notched apex

• (c) Terminal inversion of a positive T wave

• (d) All

Q7. What suggests an abnormal T wave?

• (a) Amplitude greater than accompanying “R” wave

• (b) Amplitude lesser than accompanying “U” wave

• (c) Inversion of initial portion of the T wave in leads V₁, V₂

• (d) All

Q8. Inversion of the terminal portion of the T wave with ST segment elevation suggests:

• (a) Myocardial infarction

• (b) Left ventricular hypertrophy

• (c) Myocarditis

• (d) All

Q9. Inverted proximal limb of the T wave in right precordial leads suggests diagnosis of:

• (a) ASD

• (b) VSD

• (c) PDA

• (d) TOF

Q10. T wave is produced by repolarization of:

• (a) Atrial myocardium

• (b) Ventricular myocardium

• (c) Purkinje fibers

• (d) Midmyocardial (M) cells

Q11. Polarity of a normal T wave is:

• (a) Same as net polarity of the preceding QRS complex

• (b) Opposite to the direction of the terminal part of the QRS

• (c) Opposite to the direction of the initial part of the QRS

• (d) Opposite to net polarity of the preceding QRS complex

Q12. Top of normal T wave is:

• (a) Rounded

• (b) Peaked

• (c) Flat

• (d) Notched

Q13. In normal T wave:

• (a) The two limbs are asymmetrical

• (b) Proximal limb has obtuse angle with base line

• (c) Distal limb has relatively acute angle with base line

• (d) All

Q14. Normally T wave in lead I is:

• (a) Positive

• (b) Negative

• (c) Biphasic

• (d) Notched

Q15. Normally T wave in lead V₁ can be:

• (a) Flat

• (b) Negative

• (c) Initial negative, terminal positive

• (d) Initial positive, terminal negative

Q16. Normally T wave in lead III can be:

• (a) Positive

• (b) Negative

• (c) Biphasic

• (d) Any of the above

Q17. Normal T wave in lead V₅ is:

• (a) Positive

• (b) Flat

• (c) Inverted

• (d) Any of the above

Q18. In normal persons, T wave in lead aVL:

• (a) Does not exceed 0.5 mV

• (b) Exceeds 1 mV

• (c) Exceeds 1.5 mV

• (d) Exceeds amplitude of preceding R wave:

Q19. In normal persons T wave in lead V₄

• (a) Does not exceed 0.5 mV

• (b) Does not exceed 1.0 mV

• (c) Does not exceed 1.5 mV

• (d) Exceeds amplitude of preceding R wave

Q20. In normal persons:

• (a) Direction of the T wave is opposite to that of the accompanying U wave

• (b) Amplitude of T wave is less than the amplitude of the accompanying U wave

• (c) Amplitude of the T wave is equal to the amplitude of the accompanying U wave

• (d) Amplitude of the T wave is more than the amplitude of the accompanying U wave

Q21. In juvenile pattern T waves are:

• (a) Inverted in leads I, aVL, V₆

• (b) Inverted in leads V₁ to V₄

• (c) Inverted in leads V₅, V₆

• (d) Inverted in leads II, III, aVF

Q22. In early repolarization variant:

• (a) J point is mildly elevated

• (b) Initial part of T wave is positive

• (c) Terminal part of T wave is negative

• (d) All of the above

Q23. In early repolarization variant:

• (a) Initial part of T wave is negative

• (b) Terminal part of T wave in positive

• (c) T wave becomes inverted on exercise

• (d) T wave becomes normal on exercise

Q24. Early repolarization variant in usually seen in:

• (a) Lead III

• (b) Lead aVR

• (c) Lead V₄R

• (d) Leads V₃, V₄

Q25. Combination of sinus bradycardia, low voltage of all wave forms with flat T waves suggests the possibility of:

• (a) Acute pericarditis

• (b) Pericardial constriction

• (c) Cardiac tamponade

• (d) Myxedema

Q26. Combination of sinus tachycardia, low voltage of all wave forms with flat T waves suggests possibility of:

• (a) Pericardial effusion

• (b) Myxedema

• (c) Hypokalemia

• (d) Amiodarone therapy

Q27. Combination of normal heart rate, flat T waves, prominent U waves, and prolonged QTc interval suggest the possibility of:

• (a) Cardiac tamponade

• (b) Pericardial constriction

• (c) Amiodarone therapy

• (d) Hypokalemia

Q28. Electrocardiographic findings of myxedema do not include:

• (a) Sinus tachycardia

• (b) Prominent P wave

• (c) Flat T wave

• (d) Prolonged QTc interval

Q29. Electrocardiographic findings of pericardial effusion do not include:

• (a) Sinus tachycardia

• (b) Prominent P wave

• (c) Flat T wave

• (d) Prominent “U” wave

Q30. Electrocardiographic findings of hypokalemia do not include:

• (a) Flat P wave

• (b) Broad QRS

• (c) ST segment depression

• (d) Flat T wave

Q31. The normal T wave can be flat in:

• (a) Lead V₁

• (b) Lead III

• (c) Lead aVF

• (d) All

Q32. In the context of coronary artery disease, flat T wave can be seen:

• (a) During evolution of non ST-segment elevation acute coronary syndrome

• (b) Residual pattern of old myocardial infarction

• (c) During acute ischemia

• (d) All

1.1 Answers

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