Arrythmia

Question 1

What are the

• symptoms
• ways of classifying
• 2 causes

Answer 1

Symptoms

• palpitation
• SOB
• dizzy, faint, syncope

Rate
-bradyarrythmia/tachyarrythmia

Location
-supraventricular/ventricular

Cause of bradycardia

• SAN slows
• SAN blocked, distal pacemakers take over

Causes of tachycardia

• Reentry
• Afterdepolarizations

ISSUES WITH IMPULSE GENERATION?CONDUCTION

Question 2

What is a 3rd degree HB

• causes
• effects
• prognosis
• treatment
• ECG reading

Answer 2

Electrical block between A and V

Cause

• atherosclerotic CHD
• dilated cardiomyocytes => ischemic damage
• BB fibrosis

Effects
-bradycardia as latent PM takes over

Prognosis

• death if latent PM does not take over
• increased risk of asystole if more distal

Treatment
-permanent/temporary PM

ECG
-P and QRS dissociates completely

Question 3

What is the mechanism behind tachyarrythmias

-reentry of trapped impulse

Answer 3

Impulse can only travel down conductivity system
Zone of ischemia has unidirectional conductivity, has slowed retrograde conduction

AP in this zone can only fire when tissue is not refractory

Question 4

What is the mechanism behind tachyarrythmias
-triggered automaticity

What are the 2 types and what are they triggered by

Answer 4

Delayed afterdeloparization

• excess increased [Ca] => NaCa exchange
  
  • increased NA/A
  • Digoxin (increases vagus, decreases NaKATPase but)

Early after depolarization

• AP, Ca plateau sustained
  
  • hypoxia
  • increased NA/A
  • soltalol

Can be sustained by reentry

Question 5

What is ventricular tachycardia

• causes
• effects
• prognosis
• treatment
• ECG

Answer 5

Ectopic 120-200BPM

Cause

• reentry, ectopic from cardiac scarring
• congenital

Effects
-tachy, mono/polymorphic

Prognosis

• may compromise function => HF and death
• VF => sudden death

Treatment

• ICD
• Class !, 2, 3
• radiocatheterablation (hot/cold)

ECG

• monomorphic
• polymorphic
• P hard to see as refractory period is more frequent

Question 6

What is atrial fibrillation

• cause
• risk factors
• prognosis
• treatment
• ECG

Answer 6

Chaotic atria, irregularly irregular ventricles

Cause
-ectopic/reentrant path in atria/pulmonary vein

Risk factors

• atrial dilation
• HF
• HTN
• hyperthyroidism, alcohol, age

Prognosis

• paroxysmal => persistent => permanent
• lack of atrial beat => stasis => thrombi in appendage => stroke

Treatment

• Class 1, 2, 3, 4 drugs
• CD
• radiocatheter ablation
• anticoagulants, LA appendage closed

ECG

• fibrillatory f waves
• no P waves, tacky QRS

Question 7

What is ventricular fibrillation

• cause
• effects
• prognosis
• treatment
• ECG

Answer 7

Just chaos

Cause
-MI, CHD, cardiomyopathy

Effects
-poor CO

Prognosis
-leads to death

Treatment
-DF

ECG
-disorganised until heart dies

Question 8

What are the 4 drug classes

Answer 8

I, Na block

II, B block

III, K block => Increase AP, RP

IV, Ca block

Question 9

What are the 2 other drugs that can be used in arrhythmias

Answer 9

Adenosine

• K open, Ca block
• Increases hyperpolarisation at AVN

Digoxin
-increase vagus stimulation

Question 10

What drugs control the rate

How do they do this

Answer 10

2, 4
Adenosine, digoxin
Decrease AVN conduction => decreased ventricular depolarization rate => increased filling time => CO increases

Question 11

What drugs control the rhythm

How do they do this

Answer 11

1, 3

Decrease conduction OR increase the refractory period to prevent arrhythmia reentyr

Question 12

What drug class does amiodarone belong to
What does it do
What is its T1/2
Why is this a problematic drug

Answer 12

Class 3, K blocker

Very long T1/2 => many DDI even after it has been stopped
Many severe SE

Question 13

What is radio frequency catheter ablation

What kind of arrhythmias are treated with this method

Answer 13

Ectopic pacemaker/part of reentrant pathway destroyed w heat/cold

More commonly used with SV
Harder in VT as wall is thicker

Question 14

How do implant DFs work
Where are they inserted
What are the limitations of this management method

Answer 14

RV, SVC
Sense, differentiate arrhythmias by rate/location => shock => cardio version

But too many => cardiac damage

Question 15

How do DFs work

When would you use them

Answer 15

Terminate VF/VT with no CO

Cardioversion at sternum and RV apex
=> SAN reasserts sinus rhythm

+CPR + adrenaline