Week 113 - Syncope

Question 1

What is Syncope?

Answer 1

A transient loss of consciousness due to transient global cerebral hypoperfusion characterised by sudden onset, short duration and a complete spontaneous recovery.

Question 2

What is vasovagal syncope?

Answer 2

• A vasovagal episode is one that is mediated by the vagus nerve.
• The mechanism is as follows;
• Peripheral vasodilation and venous pooling of blood leads to a reduction in blood return to the heart.
• The near-empty heart then contracts vigorously which stimulates stretch receptors which trigger reflexes in the CNS.
• The CNS tries to reduce the stetch of the left ventricle through further vasodilation and bradycardia, leading to syncope.

Question 3

What are some of the associated symptoms of vasovagal syncope?

Answer 3

Nausea, dizziness, sweating, tinnitus, yawning and a sinking feeling.

Question 4

On an ECG trace how many ms is a small square worth?

Answer 4

40ms.

Question 5

How wide should a normal QRS complex be?

Answer 5

Up to 120ms, 3 small squares.

Question 6

How wide should a normal PR interval be?

Answer 6

120-200 ms, 3-5 small squares.

Question 7

What does the P wave represent?

Answer 7

It is atrial depolarisation.

Question 8

What does a peaked, notched or enlarged P wave indicate? What may this be due to?

Answer 8

Atrial Hypertrophy, which may be due COPD, pulmonary emboli, vascular disease or heart failure.

Question 9

Varying P waves may indicate what?

Answer 9

That the impulse is coming from various sites, possibly due to irritable atrial tissue or damage near the SAN.

Question 10

What does the PR interval represent?

Answer 10

This is the atrial impulse through the AV node, bundles of His and left and right bundle branches.

Question 11

A normal PR interval should last 120-200ms (3-5 small squares), what is indicated if it is longer or shorter than this range?

Answer 11

• Shorter- The impulse originated somewhere other than the SA node, this variation is associated in preexcitation syndromes and junctional arrhythmias.
• Longer - Delay through the atria or AV junction due to digoxin toxicity or heart block.

Question 12

What does the QRS complex represent?

Answer 12

The depolarisation of the ventricles.

Question 13

What might a deep, wide Q wave represent?

Answer 13

Myocardial infarction.

Question 14

What might a notched R wave indicate?

Answer 14

A bundle-branch block.

Question 15

What might a widened QRS complex indicate?

Answer 15

A ventricular conduction delay.

Question 16

What does the ST segment represent?

Answer 16

This is the end of ventricular depolarisation and the start of ventricular repolarisation.

Question 17

What might a depressed ST segment indicate?

Answer 17

Myocardial ischaemia or digoxin toxicity.

Question 18

What might an elevated ST segment indicate?

Answer 18

Myocardial injury.

Question 19

What does the T wave represent?

Answer 19

It represents ventricular recovery or repolarization.

Question 20

What might tall, peaked or tented T waves indicate?

Answer 20

They may indicate myocardial injury or hyperkalaemia.

Question 21

What is second-degree type 1 block?

Answer 21

• Also known as Wenkebach.
• This is a progressively longer PR interval until a QRS complex is dropped and the cycle starts again.

Question 22

What is second-degree type II heart block?

Answer 22

• This is where the PR interval is regular, but a QRS complex is dropped.

Question 23

What is third-degree heart block?

Answer 23

This is when there is a complete dissociation between P-waves and QRS complexes.