113 - Syncope and heart block

Question 1

How long should a PR interval be?

Answer 1

120-200ms (3-5 small squares)

Question 2

How long should the QT interval be?

Answer 2

<0.45s

Question 3

Which bundle has a block in right axis deviation?

Answer 3

LBB - posterior fascicle

Question 4

Which bundle has a block in left axis deviation?

Answer 4

LBB - anterior fascicle

Question 5

What would you notice about the PR interval on an ECG of a 1st degree heart block?

Answer 5

• PR interval would be prolonged > 0.2s
• impulse from the atria and ventricles are slower

Question 6

What is seen on an ECG showing Mobitz 1 (Wenkebach) heart block?

Answer 6

Gradual progressive PR interval prolongation and dropped QRS

Question 7

What is meant by 2:1 Mobitz?

Answer 7

2 p waves for every QRS

Question 8

What characterises type 2 2nd degree heart block?

Answer 8

Intermittent non-conductive P wave not preceded by a QRS complex

Question 9

What is 3rd degree heart block?

Answer 9

Discordant contraction of the atria and ventricles i.e. no association between the p waves and the QRS complexes

Question 10

In which leads would an inferior infarct be seen?

Answer 10

• L2
• L3
• aVF

Question 11

In which leads would a lateral infarct be seen?

Answer 11

• L1
• aVL
• chest leads V1-V4

Question 12

In which leads would an anterior infarct be visible?

Answer 12

Chest leads V1 –> V4

Question 13

Which conduction structure is situated at the opening of the coronary sinus?

Answer 13

AV node

Question 14

Define pulse pressure

Answer 14

The difference between systolic and diastolic pressure

Question 15

Which part of the cardiac cycle is the longest?

Answer 15

Diastole (60%)

Question 16

What is the purpous of the Windkessel effect?

Answer 16

To dampen down the effect of the pulsatile blood flow to the viscera

Question 17

Which vessels hold 70% of the total blood volume?

Answer 17

Veins

Question 18

How can veins and venules control CO?

Answer 18

By constricting - increase atrial pre-load to increase CO

Question 19

Which vessels have the most resistance in the CVS?

Answer 19

Arterioles

Question 20

How is mean arterial pressure calculated?

Answer 20

CO x TPR

(cardiac output x total peripheral resistance)

Question 21

Where are the baroreflex cells found?

Answer 21

• arch of aorta
• carotid sinus

Question 22

Which CNs are involved with taking the baroreflex signals to the nucleus of the solitary tract in the brainstem?

Answer 22

CN IX and X (glossopharyngeal and vagus)

Question 23

Where are the vaso vasorum found?

Answer 23

In the walls of the larger arteries –> blood supply to the tunica adventitia

Question 24

Name 3 types of capillaries

Answer 24

• continious
• fenestrated
• discontinuous

Question 25

What is another name for discontinuous capillaries?

Answer 25

Sinusoids

Question 26

Where are discontinuous capillaries found?

Answer 26

• liver
• spleen
• bone marrow

Large proteins are able to cross

Question 27

What is the term given to the point where blood pressure is unaltered by tilting ?

(just below the transition from abdo to thorax)

Answer 27

Hydrostatic indifference point