Cardiovascular Effects of Autonomic Agents Flashcards Preview

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Flashcards in Cardiovascular Effects of Autonomic Agents Deck (41):
1

Name an indirect parasympathetic agonist

Edrophonium

2

What is edrophonium?

Short lasting ACh-esterase inhibitor that stimulates strong parasympathetic discharge for about 30 seconds

3

Side effects of edrophonium?

Profound abdominal cramping by stim smooth muscle contractions in GI

4

What are the clinical uses of edrophonium?

Used to inc AV refractoriness for brief periods
-Diagnose supravent tachyc
-Breaks supravent tachycs

5

What is a muscarinic agonist?

Agonist for parasympathetic NS (ACh)

6

List 3 adrenergic endogenous agonists

Epineph, norepi, dopamine

7

List 3 sympathetic adrenergic agonists

Phenylephrine, dobutamine, isoproterenol

8

Alpha 1: locations and actions

Vasc smooth m--constriction (mainly at skin, kidney, GI where they are most densely populated and also at large veins)

Genitourinary smooth m---constriction

9

Alpha 2: locations and actions

Vasc smooth m--constrict
Platelet aggregation

10

Beta 1: locations and actions

Heart--inc in inotropy and chronotropy (inc in HR, velocity of impulse, metabolic rate, inotropy, dec in refractoriness)

Kidney--renin secretion

11

Beta 2: locations and actions

Vasc smooth m---vasodilation (arteriolar vasodilation)
Airway smooth m--dilation

12

What receptors does epinephrine work on?

It is a mixed alpha, beta 1 and beta 2 agonist

13

What does epinephrine do to the SVR?

Stays the same because alpha constricts, but beta vasodilates

14

What does epinephrine do to the HR?

Increases it because beta 1 activity overrides baroreceptor mediated slowing which was stimulated due to inc in BP-->increase in inotropy

15

What does epinephrine do to the CO?

Increases CO which is redistributed away from skin, GI, kidney due to alpha mediated vasoconstriction

16

What does epinephrine do to the BP?

Increased CO leads to inc in BP=CO X SVR

17

What receptors does norepi work on?

Mixed alpha and beta 1 with little beta 2 activity

18

What does norepinephrine do to the SVR?

Increases it due to alpha 1 vasoconstriction and lack of beta 2 offsetting vasodilation

19

What does norepinephrine do to the HR?

Decrease it due to activation of baroreceptor reflex. SVR increase is so profound, that beta 1 cannot offset the baroreceptor reflex.

20

What does norepinephrine do to the CO?

Unchanged or slight decrease. SVR increases LV afterload offsetting some of the inotropy (which would have inc SV). In addition, HR is going down due to the baroreceptor reflex.

Beta 1 activity opposed by the strong alpha activation on SVR and vagal discharge. CO is shunted away from kidneys, GI, skin

21

What does norepinephrine do to the MAP?

Increased due to inc SVR

22

What receptors does dopamine work on?

Mixed alpha, beta 1 agonist with little beta 2 activity

23

What is special about the way dopamine works?

Its effects depend on its dosages

24

Dopamine actions at low dose

Produces predominantly renal vasodilation

25

Dopamine at intermediate dose

Beta 1 action combines with dopaminergic action (ie inc renal vasodilation) to inc CO with minimal effect of systemic vascular resistance

26

Dopamine at high dose

Alpha action overwhelms dopaminergic action and the effect is similar to norepi with lots of vasoconstriction

27

What do we use dopamine clinically for?

It is a good presser and at low to medium doses, does not reduce renal blood flow

28

What is Phenylephrine?

Synthetic adrenergic agonist that is a predominant alpha agonist with little beta activity

29

What does Phenylephrine do to the SVR?

Increase

30

What does Phenylephrine do to the HR?

Decrease: activation of baroreceptors causes vagal discharge

31

What does Phenylephrine do to the CO?

Small decrease due to increase in afterload

32

What does Phenylephrine do to the MAP?

Increase

33

What is Isoproterenol?

Synthetic beta agonist

34

What does Isoproterenol do to the SVR?

Decrease

35

What does Isoproterenol do to the HR?

Increase due to beta 1 chronotropic stimulation

36

What does Isoproterenol do to the CO?

Increases due to inc in LV contractility and dec in SVR

37

What does Isoproterenol do to the MAP?

Possible slight dec

38

What is Dobutamine?

Synthetic predominant beta 1 agonist with modest beta 2 activity. PRedominant inotropic with moderate chronotropic activity

39

What does Dobutamine do to the BP?

Little effect because of modest beta 2 activity

40

When do we use Dobutamine?

Effective for circulatory support in severe congestive HF because it is a relatively pure myocardial inotrope with modest effect on HR and little effect on peripheral circulation

41

When should you clinically use adrenergic agonists?

As an adjunctive therapy to support a pt hemodynamically while they are in shock