arrhythmias

Question 1

what is sinus tachycardia?

Answer 1

Rate of 100-180 beats/min, occurs during exercise or other conditions that lead to increased SA nodal firing rate

Question 2

what is atrial tachycardia?

Answer 2

3 or more consecutive premature atrial beats at a frequency of over 100 per min

Question 3

what is paroxysmal atrial tachycardia?

Answer 3

tachycardia which begins and ends acutely

Question 4

what is atrial flutter?

Answer 4

250-350 beats per minute

Question 5

what is atrial fibrillation?

Answer 5

uncoordianation of atrial beats

Question 6

what is an AV block?

Answer 6

impaired impulse conduction from the atria to the ventricles

Question 7

what is a healthy heart rate?

Answer 7

60-100bpm

Question 8

what is CHADSVAS score used for?

Answer 8

to assess the risk of stroke in atrial fibrillation patients

Question 9

what does CHADSVAS stand for?

Answer 9

congestive heart failure, hypertension, age over 75, diabetes, stroke or TIA previously, vascular disease, age 65-75, sex - female

Question 10

what are the 3 first line treatments for AF?

Answer 10

beta blocker, calcium channel blocker, cardiac glycoside e.g digoxin

Question 11

what is the charge of a cell at rest?

Answer 11

-85mv

Question 12

what is the depolarisation threshold in mv?

Answer 12

-70mv

Question 13

describe the stages of an action potential graph?

Answer 13

straight start and end: resting potential
incline: depolarisation where Na+ channels open
decline: repolarisation where Na+ channels close and K+ channels open
dip: refractory period

Question 14

what is the role of pacemaker cells?

Answer 14

to cause adjacent cardiac muscle cells to reach the voltage threshold initiating cardiomyocyte action potential

Question 15

when do re-entry disorders occur in the heart?

Answer 15

when an impulse arrives at myocardium refractory caused by slow repolarisation

Question 16

what is each class of the Vaughan William classification system of anti-arrhythmic drugs?

Answer 16

1a: intermediate action Na+ channel blocker
1b: slow action Na+ channel blocker
1c: fast action Na+ channel blocker
2: beta blocker
3: K+ channel blocker
4: Ca2+ channel blocker
5: other or unknown

Question 17

what do class 1a intermediate action sodium channel blockers do?

Answer 17

cause moderate phase 0 (depolarisation) depression and increase the duration of action potentials

Question 18

what do class 1b slow action sodium channel blockers do?

Answer 18

cause weak phase 0 depression and shorten depolarisation so decrease action potential duration

Question 19

what do class 1c fast action sodium channel blockers do?

Answer 19

cause strong phase 0 depression and increase action potential duration

Question 20

what do class 2 beta adrenoreceptor blockers do?

Answer 20

reduce the rate of spontaneous depolarisation of the SA and AV nodes

Question 21

what do class 3 K+ blockers do?

Answer 21

prolong phase 3 repolarisation

Question 22

what do class 4 Ca2+ blockers do?

Answer 22

slow the rate of spontaneous depolarisation