CVS - cardiac rhythms

Question 1

each side of the transport system?

Answer 1

• pulmonary
• systemic

Question 2

What factors affect cardiac output?

Answer 2

• pregnancy
• excerise
• respiration
• age

Question 3

What is responsible fort the blood supply?

Answer 3

4 coronary arteries supply blood to the heart muscle

• right/ left coronary artery

Question 4

What are the types of myocardial infraction? (MI)

Answer 4

1) spontaneous infraction related to ischaemia due to a primary coronary event such as plaque erosion and rupture

2) Mi secondary to ischaemia due to either ^ oxyfen demand or dec. supply

3) sudden unexcpected cardiac death

4) MI associated with percutanous coronary intervention

5) Mi associated w cardiac surgery

6) multifactorila aetiology, acute or chronic based on change in cardiac troponin concentrations w serial testing

Question 5

STEMI

Answer 5

ST elevation

Question 6

What happens in cardiac pacemaker cells?

Answer 6

1. intrinsic cardiac conduction system
2. Gap junctions
   - intracellulcar calcium channels
   - voltage dependant calcium chanel in the plasma membrane

Question 7

depolarisation means…

Answer 7

a wave of positive charge

Question 8

What change effects AP

Answer 8

chnage in Na, Ca, K

Question 9

Absolute refractory period (ARP)

Answer 9

the cell is completely unexcitable to a new stimulus.

Question 10

Effective refractory period (ERP):

Answer 10

ARP + short segment of phase 3 during which a stimulus may cause the cell to depolarize minimally but will not result in a propagated action potential (i.e. neighbouring cells will not depolarize).

Question 11

Relative refractory period (RRP):

Answer 11

greater than normal stimulus will depolarize the cellandcause an action potential.

Question 12

Supranormal period

Answer 12

ahyperexcitableperiod during which a weaker than normal stimulus will depolarize the cells and cause an action potential

Question 13

Sinus Node

Answer 13

Primary pacemaker
Fires at a rate of 60-100 depolarisations per minute

Question 14

AV node

Answer 14

Base of RA
Fires at a rate of 40-60 dpm

Question 15

Ventricular (Bundle of His)

Answer 15

Right and left branches
Fires at a rate of 20-40 dpm

Question 16

Ventricular (Purkinje Fibers)

Answer 16

Less than 40 dpm

Question 17

main components of an ECG? (letters)

Answer 17

P, Q, R, S, T

Question 18

PR segment

Answer 18

Pause between SA and AV node

Question 19

ST segment

Answer 19

Should be at isoelectric line if elevated more than 2 small boxes (2mV) could signal issues infarction or ischaemia

Question 20

PR Interval

Answer 20

Normal 0.12-0.20s [3-5 little boxes]
SAN firing - depolarisation of atria - pause at AV node

Question 21

QRS Interval

Answer 21

Normal <0.10 [2.5 little boxes])
Depolarisation of the ventricles and repolarisation of the atria (pump efficiency

Question 22

QT Interval

Answer 22

normal >440ms ♂ or >460ms ♀ @60bpm
N.B. RATE DEPENDENT need to calculate corrected QT (Bazett formula)

Question 23

If QT prolonged then youre trying to contract a heart that is still trying to _____
atrial ectopic focus

Answer 23

relax

Question 24

___________ occurs at a pacemaker cell (not SAN) close to or further away from AV node than the SAN

Answer 24

depolaristaion

Question 25

What factors sffect QT interval

Answer 25

1. Plasma Ca
2. Medicatioms - amplodipine (affects ion channels)
3. Genetics - mutations in LQT1/2/3

Question 26

hypercalcemia

Answer 26

short QT interval

Question 27

Hypocalemia

Answer 27

long QT interval

Question 28

Dysrhythmia

Answer 28

Impulse formation
Altered conduction

Question 29

What does an Abnormal ECGs look like?

Answer 29

1. characteristic shape-change in an ECG
2. other conditions results in changes in cardiac rhythm