ECG: Abnormalities of P waves, QRS complexes and T waves

Question 1

What are the causes and ECG correlate of right atrial hypertrophy ?

Answer 1

tricuspid valve stenosis or pulmonary hypertension)
causes the P wave to become peaked.

Question 2

What is the ECG correlate of left atrial hypertrophy ?

Answer 2

broad and bifid P wave

Question 3

What is the normal height of the R wave in lateral V1 and V2 chest leads?

Answer 3

<25 mm.

Question 4

what is the size of the septal Q waves in lateral chest leads ?

Answer 4

< 1mm wide and <2 mm deep.

Question 5

What are the causes of wider QRS complex?

Answer 5

• BBB
• ventricular extrasystole
• Ventricular escapes
• WPW syndrome.

Question 6

What is the causes of tall QRS ?

Answer 6

Ventricular hypertrophy.

Question 7

What are the ECG correlates of RVH ?

Answer 7

Tall R wave in V1 and deep S wave in V6. There is also Right axis deviation, There may also be a peaked P wave due to concomitant right atrial hypertrophy. There may also be T wave inversion in from Lead V1 to V4.

Question 8

What are the ECG correlates of pulmonary embolism ?

Answer 8

In many cases there may be no ECG changes except sinus tachycardia. However, in some cases there maybe:
1. peaked P waves
2. right axis deviation (S waves in lead I)
3. tall R waves in lead V1
4. right bundle branch block
5. inverted T waves in lead V1
(normal), spreading across to lead
V2 or V3
6. a shift of transition point to the left, so that the R wave equals
the S wave in lead V5 or V6 rather than in lead V3 or V4
(clockwise rotation); a deep S wave will persist in lead V6
7. curiously, a ‘Q’ wave in lead III resembling an inferior
infarction

Question 9

What are the ECG correlates of LVH ?

Answer 9

The Sokolov-Lyon voltage criteria: S wave depth in V1 + tallest R wave height in V5-V6 > 35 mm
Increased R wave peak time > 50 ms in leads V5 or V6
ST segment depression and T wave inversion in the left-sided leads: AKA the left ventricular ‘strain’ pattern.

Question 10

What are the ECG correlates of posterior wall MI?

Answer 10

An isolated dominant R wave pattern in V1 with flattened T waves in lead 1 and aVL. The Axis will be normal. It is often misdiagnosed.

Question 11

What are the causes of STE ?

Answer 11

OMI or acute pericarditis ( STE seen in most leads).

Question 12

What is the causes of ST depression with upright T waves ?

Answer 12

acute ischemia.

Question 13

A downward sloping as opposed to horizontal depression of ST segment is a sign of ?

Answer 13

Digoxin toxicity.

Question 14

What is the ECG correlate of partial thickness OMI ?

Answer 14

Inverted T wave.

Question 15

T wave inversions in LVH and RVH ?

Answer 15

can be seen in corresponding leads

Question 16

T wave inversion lead V3 is abnormal in ?

Answer 16

White adults.

Question 17

What are the ECG correlates of hypokalemia ?

Answer 17

A low potassium level causes T wave flattening and the appearance
of a hump on the end of the T wave called a ‘U’ wave.

Question 18

What are the ECG correlates of hyperkalemia ?

Answer 18

A high potassium level causes peaked T waves with the disappearance of the ST segment. The QRS complex may be widened.

Question 19

What are the ECG correlates of hypomagnesima and hypermagnesima ?

Answer 19

same as potassium changes.

Question 20

What are the ECG correlates of low and high calcium levels ?

Answer 20

A low plasma calcium level causes prolongation of the QT interval,
and a high plasma calcium level shortens it.

Question 21

ECG correlates of mitral stenosis ?

Answer 21

Bifid P waves in the absence of signs of associated left ventricular
hypertrophy can indicate mitral stenosis.