Surgery - Cardiovascular Complications In Anesthesia

Front 1

Bradycardia
-definition in dog

Back 1

< 60 (avg. for breeds/size)

Front 2

Bradycardia
-definition in cat

Back 2

< 100 (avg. for breed/size)

Front 3

Bradycardia commonly seen during anesthesia

Back 3

-bradycardia with 2nd Degree AV block

Front 4

What is this?

Back 4

-sinus bradycardia with 2nd degree AV block

Front 5

Is slow heart rate always deleterious?

Back 5

-no, it depends on the demand

Front 6

Cardiac output =

Back 6

CO = heart rate x stroke volume

Front 7

Cardiac output
-can usually be improved by:

Back 7

-increasing HR

*HR will eventually become to fast to allow for optimal diastolic filling

Front 8

Bradycardic patient
-blood pressure

Back 8

-normotensive
or
-hypotensive
or
-hypertensive

Front 9

Bradycardia
-blood pressure can be an indication for:

Back 9

-cause of bradycardia
-guide for necessity of treatment

Front 10

Phenylephrine
-effect on ABP, MAP, HR

Back 10

-reflex bradycardia

Front 11

Bradycardia
-causes

Back 11

-vagal stimulation ---> inc. PNS tone
-vagomimetic drugs
-plane of anesthesia too deep
-hypothermia
-myocardial hypoxia
-hyperkalemia
-closed pop-off
-increased intracranial pressure (cushing reflex)
-cardiac disease

Front 12

Vagomimetic drugs that cause bradycardia

Back 12

-Alpha-2 agonists
-opioids

Front 13

How does hypothermia cause bradycardia?

Back 13

-delayed depolarization of the SA node
-non-responsive to anticholinergics (atropine)

Front 14

How does a closed pop-off valve cause bradycardia?

Back 14

-increased intrapleural pressure
--decreased venous return
---increased aortic pressure
----reflex bradycardia

Front 15

Ways cardiac disease causes bradycardia

Back 15

-AV conduction disturbance
-3rd degree AV block
-Sick sinus syndrom

Front 16

When to treat bradycardia

Back 16

-to improve cardiac output
-low blood pressure
-underlying cardiac disease
-poor tissue perfusion
-hypovolemia

Front 17

Bradycardia
-treatment

Back 17

-Determine the initiating cause and correct obvious problems
-Anticholinergic

Front 18

Bradycardia
-when to use and anticholinergic to treat

Back 18

-if vagal stimulation is the probable cause and no other cause is obvious

Front 19

Bradycardia
-anticholinergics to treat with

Back 19

-atropine
-glycopyrrolate

Front 20

Tachycardia
-definition in dog

Back 20

> 180

Front 21

Tachycardia
-definition in cat

Back 21

> 200

Front 22

Tachycardia
-tolerance to higher heart rate

Back 22

-smaller animals can tolerate higher
-underlying heart disease will lower tolerance

Front 23

Tachycardia
-causes

Back 23

-excess sympathetic drive
-hypovolemia
-pathology

Front 24

Excess sympathetic drive
-caused by

Back 24

-high PaCO2
-Pain
-Light anesthesia
-Sympathomimetics

Front 25

Sympathomimetic drugs

Back 25

-ephedrine
-dobutamine
-dopamine
-ketamine

Front 26

How does hypovolemia cause tachycardia?

Back 26

-baroreceptor reflex

*not reliable in an anesthetized patient because response is suppressed by opioids

Front 27

Tachycardia
-pathological causes

Back 27

-cardiac disease
-hyperthyroidism
-pheochromocytoma

Front 28

Tachycardia
-effect on diastolic time

Back 28

-decreases diastolic time

Front 29

Effect of decreased diastolic time on the heart

Back 29

-less time for ventricular filling

-less time for myocardial perfusion (occurs during diastole)
--increased myocardial work and need for O2
---oxygen demand can exceed O2 supply

Front 30

Tachycardia
-treatment

Back 30

Treat initiating cause
-insure good analgesia
-guarantee good anesthetic depth
-IPPV
-Increase IV fluid rate if indicated for hypovolemia
-Reduce dose of sympathomimetics if indicated
-Consider a beta-adrenergic blocker to reduce rate if severe tachycardia

Front 31

How to insure good analgesia to treat tachycardia

Back 31

Opioids
-fentanyl (fast acting)

Front 32

Why may you need to use IPPV to treat tachycardia?

Back 32

-a normalized PaCO2 may decrease the heart rate

Front 33

Ventricular Extrasystole
-types

Back 33

-Premature ventricular complex
-Escape beat

Front 34

Ventricular extrasystoles
-ECG unique finding

Back 34

-Wide QRS
- opposite T wave polarity

Front 35

Ventricular Premature Complex
-causes

Back 35

-myocardial disease/injury
-pain
-hypoxia
-acidosis
-severe hypothermia
-drugs
-electrolyte disturbances

Front 36

Drugs that can cause VPCs

Back 36

-xylazine
-thiopental
-halothane

Front 37

Electrolyte disturbance that can cause VPCs

Back 37

-high K (hyperkalemia)

Front 38

Escape beat
-causes

Back 38

-normal when the sinus rate is very slow
-the ventricular pacemaker takes over to keep the heart at 30-40 bpm

Front 39

Escape beat
-treatment

Back 39

-never suppress or treat (keeping patient alive)

Front 40

PVCs
-usually occur when

Back 40

HR < 30-40 bpm

Front 41

PVCs
-aka

Back 41

-idioventricular rhythm

Front 42

Accelerated idioventricular rhythm
-define

Back 42

VPCs occuring at HR = 40-100 bpm

Front 43

Ventricular tachycardia
-define

Back 43

VPCs when HR > 100 bpm

Front 44

Ventricular Arrhythmia
-treatment

Back 44

-treat initiating cause if possible
-Lidocaine IV
-Procainamide or Beta-blocker (esmolol) when lidocaine not working acutely

Front 45

When to give lidocaine CRI for ventricular arrhythmias

Back 45

-> 6/min, 3 in a row, or multifocal
-when compromising blood pressure under anesthesia
-if R on T phenomenon is observed

Front 46

Lidocaine
-drug class

Back 46

IB antiarrhythmic

Front 47

Lidocaine
-MOA

Back 47

-Na+ channel blocker reduces action potential duration and conduction velocity in myocardium