Bradycardia

Question 1

bradycardia is a decrease in heart rate to be

2 causes:

Answer 1

<60bpm

1. insufficient impulse formation (ex/ sinus node dysfunction)
2. insufficiency impulse conduction (AV Block)

Question 2

insufficient impulse formation is a result of __ __ dysfunction

insufficient impulse conduction is a result of ___ ___ dysfunction

Answer 2

insufficient impulse formation is a result of SINUS NODE dysfunction

insufficient impulse conduction is a result of AV BLOCK dysfunction

Question 3

T/F every bradycardia is pathological

Answer 3

false. athletes often have a resting heart rate of 59 bpms. “sick sinus syndrome” only occurs until symptoms develop

Question 5

What ECG manifestations would you see in someone with sinus node dysfunction (SND)

Answer 5

1. bradycardia
2. sinus pauses and sinus arrest
3. inappropriate HR repsonse to exertion
4. AV block
5. atrial flutter
   - it’s commonly seen in normal people while sleeping, but abnormal while awake.

Question 6

when there is a sinus node dysfunction causing bradycaria, ___ rhythms can take over. Outline some examples

Answer 6

ESCAPE RHYTHMS.

• atrial, junctional or ventricular escape rhythm.

Question 7

symptoms of bradycardia

Answer 7

Question 8

how do you diagnose sinus bradycardia

Answer 8

SYMPTOM-RHYTHM CORRELATION

• record inappropriately slow sinue rate during symptoms
• can be difficult to achieve, diagnosis can be a judgement call based on evidence.
• might be helpful using a holter monitor or implanted loop recorder

Question 10

chronotropic incompetence. which node affected?

Answer 10

inadequate heart rate (chronotropic) repsonse to metabolic demand

-is another feature of sinus node dysfunction

Question 11

primary sinus node dysfunction is a disease affecting the ___ ___ node. The number one cause is ___ or ___. Other causes is coronary and infiltrative disease (sarcoidosis, amyloidosis, haemochromatosis)

Answer 11

primary sinus node dysfunction is a disease affecting the SINO-ARTERIAL node. The number one cause is AGE or FIBROSIS. Other causes is coronary and infiltrative disease (sarcoidosis, amyloidosis, haemochromatosis)

Question 12

3 secondary causes fo sinus node dysfunction (DAHK)

Answer 12

1. drugs (beta blockers, calcium channel blockers)
2. autonomic (carotid hypersensitivity, vasovagal syncope)
3. hyperkalemia

Question 13

treatment for SSS

Answer 13

Question 14

note: tachy-brady syndrome can occur and cause atrio-fibrillation in addition to bradycardia

Question 15

summary. flip too

Answer 15

Question 16

first degree AV block deifnition

Answer 16

• misnomer. there is no AV block, just AV delay. the PR interval is longer than normal.
• every P wave conducts to the ventricles, just slowly.

Question 17

third degree AV block definition

Answer 17

• complete AV block/complete heart block
• no P wave conducts to the ventricles, not even one.
• The atria and ventricles are not communicating at all
   they are dissociated from each other
   Some rhythm is driving the atria
   sinus rhythm, sinus tachycardia, sinus bradycardia, atrial fibrillation etc

 Hopefully, some other rhythm is driving the ventricles
 junctional escape rhythm, ventricular escape rhythm, paced rhythm

Question 18

JVP symptoms in a complete heart block

Answer 18

cannon A waves– JVP elevation– intermittent large A waves that come all the way up the neck.

Question 19

second degree AV block

Answer 19

• some P waves conduct and some do not
• QRS complexes appear to come in groups

Question 20

Type I vs Type II second degree AV block

Answer 20

Type I; the PR interval gradually lengthens before a P wave blcoks, and the cycle begins again. This can be normal physiology for the AV node.

Type II: the PR interval remains constant before a P wave blocks and the cycle begins again.

Question 21

Type I or Type II second degree? (AV block)

Answer 21

The PR interval gradually lengthens before
a P wave blocks, and the cycle begins
again

Question 22

Type I or II second degree (AV Block)

Answer 22

The PR interval remains constant before a
P wave blocks, and the cycle begins again

Question 23

First degree AVB: slow
conduction can be in either the __ or ___

2nd degree AVB, type I:
usually __

2nd degree AVB, type II:
usually __

Third degree AVB: can
be ___

Answer 23

First degree AVB: slow
conduction can be in either the AVN or HP

2nd degree AVB, type I:
usually AVN

2nd degree AVB, type II:
usually HP

Third degree AVB: can
be either

Question 24

diagnosing an atrioventricular heart block

Answer 24

 Same as for SND: gold standard is
symptom-rhythm correlation

 Can be intermittent and difficult to
diagnose

Question 25

note: a lot of the time, a 3rd degree AVB in acute inferior MI.

Question 26

treatment for atrioventricular block

Answer 26

• reverse the reversible causes
• permanent pacemaker (not for 1st degree AV block)
• beware vasovagal syncope:
•  can cause profound AV block

 temporary reflex with an excellent prognosis

 almost never requires a permanent pacemaker

Question 27

RBBB and
LBBB are
evidence of
disease below
the ___.

Answer 27

• evidence of disease below the AVN

As long as the
AVN and the
other bundle
works, AV
conduction will
still occur

Question 28

RBBB or LBBB?

Answer 28

RBB.

• normal sinut rhythm, RsR/ in lead V1

Question 29

RBBB or LBBB

Answer 29

LBBB

 Normal sinus rhythm, LBBB

 Dominant R wave in left-sided leads: I, aVL, V6

Question 30

atrial or ventricular pacing?

Answer 30

AAI pacing
atrial

Question 31

atrial or ventricular pacing?

Answer 31

ventricular pacing

Question 32

Type of chamber pacing

Answer 32

dual chamber pacing– both ventricular and atrial