CVS session 7- The ECG and Common Abnormalities

Question 0

What are augmented leads?

Answer 0

They have 2 negative electrodes and 1 positive

Question 1

What is a ‘lead’?

Answer 1

An electrical view of the heart

Question 2

How is one view achieved from an augmented lead?

Answer 2

Convert the two negatives to one.

Then invert this one negative and add to the positive to give the final view.

Question 3

How many leads does a full ECG have and what are the components?

Answer 3

12
Leads I, II and III
Augmented leads VR, VL and VF
6 Chest leads V1-V6

Question 4

How many electrodes do augmented leads have?

Answer 4

2 negative and 1 positive

Question 5

How many electrodes do chest leads have?

Answer 5

3 negative and 1 positive

Question 6

When are pathological Q waves found?

Answer 6

• MI

- silent MI

Question 7

What is a consequence of atria not contracting in atrial fibrillation?

Answer 7

Clotting as blood pools in corners of atria.

Question 8

When does Right axis deviation occur and which Leads R wave increases as a result?

Answer 8

When blood is hard to pump to the lungs, increasing the amount of muscle on the RHS.
Lead III.

Question 9

Why does a bundle branch block lengthen and change the shape of the QRS complex?

Answer 9

The route of spread of depolarisation is altered as conducting pathways are damaged.

Question 10

What happens to the ST segment in Angina?

Answer 10

Depression

Question 11

What happens to the ST wave in an MI?

Answer 11

Elevation

Question 12

What are the two reasons that L axis deviation could occur?

Answer 12

• L ventricular hypertrophy

- conduction problem.

Question 13

What is first degree heart block, and what is the abnormality on the ECG?

Answer 13

All of the signals generated at the SAN do reach the ventricles, but there is a delay somewhere along the pathway.
P-R interval elongation

Question 14

What is second degree heart block and what is the ECG abnormality?

Answer 14

It is when there is a conduction problem between the atria and the ventricles which means that only some of the signals are reaching the ventricles.
Type 1- progressive lengthening of the P-R interval until no QRS follows.
Type 2- constant P-R intervals, but not all followed by QRS.

Question 15

What is the third degree heart block and what is the ECG abnormality?

Answer 15

It is a complete conduction block between the atria and ventricles, therefore P waves are not associated with QRS complexes as atrial contraction is not necessarily followed by ventricular contraction.
P-R interval is irregular and the QRS complex is too.

Question 16

What is Le bundle branch block and what is the ECG abnormality?

Answer 16

It is when the left branch of the huddle of His is blocked, meaning that depolarisation can’t occur in the normal way from left to right.
An ectopic signal must therefore be depolarising the left ventricle, causing a widened QRS complex as it is slower at doing so.
Lead V6- wide QRS complex with a notched top.

Question 17

What is Right bundle branch block and what is the ECG abnormality?

Answer 17

It is when there is a block of the right branch of the bundle of His. Depolarisation still occurs in the normal direction from left to right, but depolarisation of the R ventricle is slower, therefore causing a second R wave on lead V1.- RSR complex.

Question 18

Which class of arrhythmia can carotid sinus pressure be used to treat?

Answer 18

Supraventricular arrythmias

Question 19

What is a STEMI?

Answer 19

A myocardial infarction with ST elevation, pathological Q waves and T wave inversion.

Question 20

What is NSTEMI?

Answer 20

A myocardial infarction with no ST elevation as there is no pathological Q wave, but there is an inverted T wave.