L9: Cardiac Arrhythmias

Question 1

fast heart rate >100bpm

Answer 1

tachycardia

Question 2

causes of tachycardia

Answer 2

increased body temp.
sympathetic stimulation
toxic heart conditions (weakened myocardium)

Question 3

tachycardia: increased body temperature

Answer 3

HR increases by 10 bpm per 1F
or
increases by 18 per 1C

Question 4

tachycardia: sympathetic stimulation

Answer 4

severe blood loss or shock

Question 5

slow heart rate <60bpm

Answer 5

bradycardia

Question 6

causes of bradycardia

Answer 6

athletic heart
vagal stimulation
extremely sensitive carotid baroreceptors in carotid sinus syndrome

Question 7

respiratory sinus arrhythmia

Answer 7

ability to change heart rate thru inspiration/expiration cycles

thus increases/decreases number of impulses sent via the sympathetic/vagal

Question 8

exercise induced tachycardia

Answer 8

endogenously mediated tachycardia
increased HR,CO
decreased filling time but SV does not drop

Question 9

pathologically mediated tachycardia

Answer 9

increased HR

decreased CO

Question 10

what factor drops in pathological tachycardia and why?

Answer 10

cardiac output
mean arterial pressure decreases
sympathetic activated after thus not able to compensate

thus no muscles stimulated to increase venous return

Question 11

sudden cessation of P waves

Answer 11

sinoatrial block

atria standstill

Question 12

sinoatrial block

Answer 12

ventricles pick up new rhythm
QRS is slowed but not altered
P wave is missing

Question 13

causes of atrioventricular block

Answer 13

ischemia of AV/bundles
compression of AV by scar tissue
inflammation of AV
extreme stimulation of heart by vagus

Question 14

PR interval increases greater than 0.2 seconds

Answer 14

1st degree incomplete atrioventricular heart block

Question 15

PR interval increases 0.25 to 0.45 seconds

Answer 15

2nd degree incomplete atrioventricular heart block

Question 16

results of 2nd degree atrioventricular block

Answer 16

missing beats of ventricles

2:1 rhythms develop

Question 17

P wave and QRS complex are no longer related

Answer 17

complete atrioventricular block

Question 18

in atrioventricular blocks the AV node may cease conduction

Answer 18

ventricles may not beat again for 5 to 30 seconds

Question 19

ventricular escape

Answer 19

resuming of ventricular beats due to purkinje fibers acting as ectopic pacemaker

Question 20

in a complete atrioventricular block patients may…..

Answer 20

faint due to lack of blood to brain

Question 21

stokes-adams syndrome

Answer 21

fainting spells caused by complete atrioventricular blocks

Question 22

electrical alternans

Answer 22

partial intraventricular block
an alternation in amplitude of P, QRS, or T

no missing waves

Question 23

contraction occurring before it should

Answer 23

premature contraction
caused by: an ectopic focus
local ischemia
calcified plaques
irritation of conduction system or nodes

Question 24

heart suddenly beats rapidly, ranging from seconds to hours or even days

Answer 24

paroxysmal tachycardia

begins and ends suddenly
returning to normal at conclusion

Question 25

the slow-twitching of individual muscle fibers in a heart chamber

Answer 25

fibrillation

Question 26

occur when the length of the pathway remains normal but the conduction velocity of the impulse is slowed

Answer 26

circus mvt

Question 27

causes of circus mvts

Answer 27

blockage of purkinje system
ischemia
high K+ levels
response to epinephrine
response to repetitive electrical stimulation

Question 28

basis for fibrillation

Answer 28

occurs as a result of circus mvts

Question 29

why does normal ventricle depolarization die out in circus mvts and fibrillation?

Answer 29

because a portion of the heart is already in refractory period and cannot respond to a second stimulus

Question 30

3 different conditions resulting in circus mvts

Answer 30

the pathway is too long – dilated heart

length of pathway is constant but velocity has slowed

refractory period has become greatly shortened

Question 31

cardiac fibrous skeleton

Answer 31

ventricle and atria fibers are separated by this

allows each chamber to exhibit fibrillation independently of each other

Question 32

causes of atrial fibrillation

Answer 32

enlargement of atria – How?

• -valve lesions
• -inadequate emptying of ventricles

Question 33

how does inadequate emptying of ventricles enlarge the atria?

Answer 33

causes blood to back up into the atria