Quiz 7 - Sinus Rhythms

Question 1

What is a normal sinus rhythm (NSR)?

Answer 1

when (electrical) stimuli/impulse originates from SA node

The rhythm of a healthy heart

Question 2

What defines a NSR?

Answer 2

A HR of 60-100 bpm
Normal (and) similar p-waves
Normal PR Interval (PRI)
Normal QRS

*R-R details help you identify this criteria

Question 3

What are the characteristics of sinus tachycardia?

Answer 3

HR = 100 - 160bpm everything else = teh same as NSR

Originates in SA node; Rhythm - regular; Pwaves - normal and sim; PRI & QRS - normal

Question 4

What are the causes of sinus tachycardia?

Answer 4

Exercise, excitement/arousal, anxiety, drugs, medicine (including caffeine alcohol) amd an increase in PNS or a Decrease in PSNS, pain, a myocardial ischemia or infraction.

REMEMBER sinus tachy comes from the SA node - still a good sign; Ventricular tachy. means it does not derive from SA node - not so good.

Question 5

If sinus bracycardia occurs, what does that tell us about the SA node?

Answer 5

That the SA node is depolarizing at a slower rate.
(This also means cardiac output is consequently lower too)

For athletes, this can be normal (hence lower rate, but greater stroke volume), others not so much.

Question 6

What are some causes of sinus bracycardia?

Answer 6

Aerobic training; MI which can impact SA node; vagal stimulation from vomiting, carotid artery massage & straining; holding your breath; sudden mov’t to upright position; valsava (maneuver); vasovagal reactions