Arrhythmias

Question 1

What are type of arrhythmias?

Answer 1

Bradycardia 
Artial flutter 
Atrial Fibrilation 
Tachycardia 
Ventricular fibrilation

Question 2

What causes Tachycardic arrythmias?

Answer 2

Ectopic pacemaker activity (damaged myocardium= spontaneous activity)
Afterdepolariastions
Atrial flutter/ fib
Re-entry loop (blockage= extra pathway)

Question 3

Causes of Baradycardia

Answer 3

Sinus (extrinic factors effecting ca channels)
Conduction block ( slow conductance/ problems with AV node/ bundle of His)

Question 4

When are b-adrenoreceptor agoniststs used?

Answer 4

After MI- reduce sympathtic activty
Prevent supraventricular tachycardia (slows ventricular rate)
Reduce O2 demand (reduce hearts work load)

Question 5

How do B-adrenoreceptor agonists work?

Answer 5

Block sympathetic action on the heart
Decreases the slope if pacemaker potential (longer ap)
Slows conuctance at AV node
Reduces cAMP levels

Question 6

What are the types of arrythmia drugs?

Answer 6

Block voltage sensitve Na channels
Agonists of B-adrenoreceptors
Block K channels
Block Ca channels

Question 7

How do Na channel blocking drugs work?

Answer 7

Use-dependant block
Blocks open channels (damaged tissue preferntailly)
Shortens AP and reduces conductance velocity
Stops damaged areas depolarising automatically

Question 8

Whats an example of on Na channel blocking drug?

Answer 8

Lidocaine

Question 9

How do K channel blocking drugs work?

Answer 9

Prolong the action potentail (making absolute recfractory period longer)
Can be pro-arrythmic as prolongs QT interval

Question 10

What to K channel blockers treat?

Answer 10

Tacycardia associated with Wolff-Parkinson-White syndrome

As stops re-entry loop conductance

Question 11

How do Ca channel blockers work?

Answer 11

Decrease slope of apot at SA node
Decrease AV conductance
Decrease force contraction

Question 12

What is an inotropic drug?

Answer 12

Drug that alters the force of contraction

Question 13

How do ACE inhibitors work?

Answer 13

Prevent the conversion of Angiotesin 1- Angiotensin 2
Decrease the vasomotor tone
Reduce afterload
Reduce preload

Question 14

How do organic nitrates relieve Angina?

Answer 14

Is a powerful vasodilator
(Increases cGMP, lowers inracellular Ca, relaxation on smooth muscles)

Act on veneous sytem to cause venodilaton and lower preload (lowers O2 demand)
Act in collateral arteries and improve O2 delivery

Question 15

How do Organic nitrates acts preferentially on veins?

Answer 15

Less endogenous nitric oxide in veins

Has little affect on arterioles

Question 16

What heart conditions are predisposed to thrombus formation?

Answer 16

Artial fibrilation
Actute MI
Mechanical heart valves

Question 17

Drugs that treat Thrombus formation?

Answer 17

Antithrombotic drugs;
Anticoagulats (Heparin to inhibit thrombin, Warfarin antagonise vit K action)

Antiplatelet drugs (Asprin)

Question 18

How to treat heart failure?

Answer 18

Reduce workload of heart

ACE inhibitors
ARBs
Diuretics
Beta blocker

Cardiac glycosides relive symotoms but dont aid long term

Question 19

How do Diuretics work?

Answer 19

Reduce blood volume

Question 20

How to ARBs work?

Answer 20

Used if can’t tolerate ACE inbibitors

Angiotensin 2 receptor blockers

Question 21

What are example of inotropes?

Answer 21

Cardiac glycosides
B adrenergic agonists

Increase contractility and cardiac output

Question 22

How do cardiac glycosides work?

Answer 22

Block action of Na/K ATPase
Ca is normlly extruded via NA-Ca exchanger
If Na conc is higher, less Na into cell so less Ca out of cell
Increases force of contraction

Question 23

How to B adrenoreceptor agonists work?

Answer 23

Stimulate B1 receptors

Used in cardiogenic shock and reversible heart failure

Question 24

What drugs treat Hypertension?

Answer 24

ACE inhibitors
ARBs
Diuretics
Ca channel blockers