Cardiovascular

Question 1

Positive inotropes

Answer 1

Increase strength of contraction

Question 2

Negative inotropes

Answer 2

Decrease strength of contraction

Question 3

Luisotrope

Answer 3

Strength of relaxation

Question 4

Positive chronotrope

Answer 4

Increase heart rate

Question 5

Negative chronotrope

Answer 5

Decrease heart rate

Question 6

What is rate determined and controlled by?

Answer 6

Cv centre in medulla oblongata

Question 7

Controlling tachyarrythmias?

Answer 7

Sympathetic antagonists or parasympathetic agonist

Question 8

Class 1 antidysrhythmics

Answer 8

Block na channels
Slows depolarisation of myocytes
1a 1b and 1c classes
Use dependent na channel blockade- bind to cells that are firing off the most, leave normal cells alone

Question 9

Class 1a example

Answer 9

Quinidine
Used to convert atrial fibrillation in horses
Oral admin, highly protein bound
Mildly vagolytic- increases heart rate and conduction

Question 10

Class 1b example

Answer 10

Lidocaine
IV admin- 1st pass metabolism
Ventricular tachycardia- prevent premature beats
Hypotension at toxic levels

Question 11

Class 1c example

Answer 11

Flecainide
Strong
Slows depolarisation and conduction through His Purkinje system
Ventricular arrhythmia

Question 12

Class II antidysrhythmics

Answer 12

Beta blockers
Slows pacemaker production and conduction
Stops calcium phosphorylation- no contractions
Not good with patients with heart failure- vasodilation, negative lusitrophy

Eg Atenolol

Question 13

Class III antidysrhythmics

Answer 13

Block k channels- slows repolarisation
Prolong QT interval

Eg sotalol
Can cause hypotension and bradycardia

Question 14

Class IV antidysrhythmics

Answer 14

Block ca channels
Ca needed for pacemakers to depolarise
Slows conduction through SAN and AVN
good for supra ventricular tachycardia 
Also are vasodilator

Eg Diltiazem
Oral admin- 1st pass met, also parentreal admin

Question 15

Miscellaneous antidysrhythmics

Cardiac glycoside

Answer 15

Digoxin
Negative chronotrope without negative inotropes
Decreases heart rate without decreasing strength of contraction

Vagomemimetic- mimics parasympathetic
Inhibits na removal from cell
Slows conduction through AVN
Allows ventricles enough time to fill

Oral admin- highly protein bound

Question 16

Sympathomimetics

Treating bradyarrhythmias

Answer 16

Beta one agonist- Dobutamin
Increase contractility, can cause tachycardia

Beta two agonist- terbutaline
Increase heart rate, bronchodilator (reap distress)

Question 17

Anticholinergics

Treating bradyarrhythmias

Answer 17

Muscurinic antagonist
System is inhibition of parasympathetic ns
Short term use
Eg Atropine

Question 18

PDE III inhibitor

Answer 18

Eg Pimobendan
Increases intracellular cAMP and increases contractility
Activates PKA to phosphorylate ca channels- ca influx- contract

Vasodilation to decrease after load
Prevent phosphorylation of MLCK in vascular smooth muscles

Question 19

Negative inotropes??

Decrease strength of contraction?

Answer 19

Sympathetic antagonist
Cholinergics
Calcium channel blockers

Question 20

When would you want to reduce preload?

Answer 20

Congestive heart failure

Can’t cope with volume

Question 21

When would you want to reduce afterload?

Answer 21

Forward heart failure

Allows more blood to flow out

Question 22

When would you want to increase local perfusion?

Answer 22

Reduce compensatory vasoconstriction of non essential blood vessels

Question 23

When would you want to decrease systemic arterial pressure?

Answer 23

Hypertension

Question 24

Endogenous mechanisms to alter blood flow

Answer 24

Intrinsic- metabolic/paracrine (no)

Extrinsic- baroreflex, RAAS, pituitary ADH, hypothalamus thirst centre

Question 25

Direct vasodilator?

Answer 25

Nitrates Ca Channel blockers PDE v inhibitors

Question 26

Nitrates

Answer 26

Peripheral vasodilation- nitrous oxide NO-cGAMP- activates k channels to hyperpolarise cell Activates MLCP to dephosphorylates MLC-relaxation Blocks ca entry, no contraction Eg nitroglycerin Metabolised to NO Potent vasodilator , used percutaneously. Emergency situ- rapid

Question 27

Ca channel blockers- vasodilation

Answer 27

(Also class 4 antidysrhythmics) Amlodipine Really common No calcium, no contraction, blood vessels relax and dilate May cause hypotension and reflex tachycardia

Question 28

What is reflex tachycardia?

Answer 28

Cv centre has reset blood pressure at regency point higher than normal due to ongoing hypertension. When BP is lowered due to drugs, it detects a lower BP than at reference point and will work to increase it and increase heart rate

Question 29

Hydralazine

Answer 29

Uncertain method or action Arteriodilator Big drop in afterload Reflex tachycardia

Question 30

PDE V inhibitor

Answer 30

``` Sildenafil Inhibits breakdown of cGAMP activates protein kinase G Activates MLCP- dephosphorylates MLC Relaxation Vasodilation ```

Question 31

Indirect vasodilators?

Answer 31

``` Sympathetic antagonist ACE inhibitors ANGII receptor antagonists Aldosterone antagonist Anti diuretics ```

Question 32

Alpha one adrenoreceptor blockade

Answer 32

Blood vessel vasodilation Not selective- can happen at any point Not really used Eg Prazosin

Question 33

ACE inhibitors

Answer 33

Vasodilation and decrease blood volume Blocks RAAS cascade Activates in liver, renally excreted Eg Ramipril Benazepril (renal compromised patients, excreted in bile)

Question 34

ANGII inhibitors

Answer 34

Will block all formation of ANGII Eg Telmisartan Oral admin, highly protein bound, met in liver, exc in bile and urine

Question 35

Aldosterone antagonists

Answer 35

Decrease na and k retention Reduces cardiac remodelling (Decreasing k can lead to bradycardia) Eg spironolactone Oral admin, high protein bound Cardalis- benazepril+spironolactone

Question 36

Golden quadruple treatment for heart failure

Answer 36

ACE inhibitor- benezepril Aldosterone inhibitor- spironolactone Diuretic- furosemide PDE III inhibitor- pimobendan