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SAM 2 > Arrhythmias 1 > Flashcards

Arrhythmias 1 Flashcards

1
Q

What are the 2 main indications for doing an ECG?

A
  1. Arrhythmias, tachy or bradycardia i.e HB too fast, slow or eratic
  2. For monitoring anaesthesia
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2
Q

Other indications for ECG

A

Cardiac/ cardiotoxic drugs

Electolyte disturbances or after IV electrolytes

Reperfusion

Enlarged cardiac chambers

Pericardiocentesis

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3
Q

What is the physio rhythm?

A

Originates in SA node (nomotop)

Resp rhythm is physio in dogs because have higher vagal tone, sinus rhythm is physio in cats

Escape beats- from outside sinus, lower pacemakers at lower frequencies

Sometimes AV blocks can be physio in dogs

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4
Q

Normal sinus= sinus arrhythmia

A

Is this the normal PQRS complex?

P wave: atrial depol- followed by a small break of the AV node where NO wave form is visible

QRS complex- the impulse travelsv quiclkly to the ventric fibres

ALL depol is followed by repol (T-wave) but T-wave of atrial repol is. not seen on ecg

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5
Q

Physio sinus arr and wandering pacemaker

A

This is resp arr!! insp shorter distances that exp

Atria can be activated from different points hence the variation

heart beats are at the end and beginning of systole

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6
Q

Classification of arr

A

1.Impulse form:

  • normal or incr HR
  • abnormal automaticity
  • Triggered activity
  • Reentry or block

Conduction

  • slow, block can be uni or bidirectional
  • Normal or decr HR

Arr- dysrhythmias

  • tachy, brady, arr
  • Ectopic beats (except physio escape beats)
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7
Q

Impulse formative disorders, what are the 2 origins?

A

Nomtop- when from the sinus node

Heterotop/ectopic- from outsude the node!

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8
Q

Nomtop

A

Sinus tachycard

Sinus bradycard

Arrest

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9
Q

Hterotop/ectopic

A

Supra vetric:

  • Atrial extrasystolde (outside atria)
  • Foacal atrial tachycard
  • Atrial fibrillation= disorganised
  • atrial flutter= large reentry
  • junctional tachycard
  • junctional extrasystole

Ventricular:

  • extrasystole
  • Tachycard
  • Fibrillation, flutter

When is both supraventric and ventric : uses bypass tracts or bypass tachycard: atrioventric reciprocating tachycard

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10
Q

Ectopic/ extrasystole/ premature contractions

A

From anywhere outside the primary!!

Cannot distinguish whether it is coming from atria or ventricles via ausc

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11
Q

Ectopic escape beats

A

From outside the sinus node

  • big pause when there is no sinus node activity
  • in one example- there are no P-waves just QRS complexes, the HR is slow
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12
Q

Premtaure supraventric extrasystole

A

The extra beat is very similar to the sinus beat. there appears to be a very small distance btw the QRS complexes

The QRS complex is NARROW!!

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13
Q

Premature ventric contraction, ventricular extrasystole

A

Early beat is visible

The QRS complex is WIDE!! (how to distinguish from supraventric extrasystole)

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14
Q

Supraventricular premature beat, Non-compensated pause, resetting

A

If supraventric comes too early- there may be a conduction block!

Measure the distances btw the abnormal beats

Supra (originates in sinus) also depolarizes the atria. Sinus beat will come normally

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15
Q

Ventricular premature contraction, fully compensated pause, no resetting

A

It is exactly 2 QRS complexes i.e 2 cardiac cycles

Does not depol the atria therefore the next sinus beat will be a bit abnormal

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16
Q

IImpulse formative disorders- how to distinguish btw supraventric and ventric tachycardia

A

Supraventric will have positive deflections

Ventric tachycard will have negative deflections

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17
Q

Points to look out for if diagnosing ventricular extrasystole (VPC)

A
  • wide QRS
  • No P-wave
  • Abnormal T-wave
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18
Q

Diagnosing Supraventricular extrasystole?

A

Appearance of typical sinus beat

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19
Q

Supraventricular escape beat diagnosis

A

In this case it was originating from the AV node so there was no P-wave!

20
Q

Diagnosing ventricular escape beats

A

V. slow rhythm

All beats are abnormal

If sinus in origin then no P-wave (can you conclude that if the origin is SA or AV node that there will be no P-wave?)

LArge, wide, negative QRS complexes

21
Q

Impulse conductive disorders: SA blocks

A

1st degree: slow conduction

2nd degree: maybe conduction

3rd degree: no conduction

Bundle branch block (BBB) can be left or right

Intraventricular conduction blocks!

22
Q

Blocks can be…

A

Functional: R bundle branch block is frequent! or when the beat comes too early, before the tissues have regained conductivity

Physio: premature ventric beat with aberrant conduction

Blocked premature supraventricular beat-completely blocked T-wave! In these cases the block is physio but the premature stimulus of the atria is patho!

23
Q

3 main Causes of arr

A
  1. Structural HD/HF
  2. Systemic illness
  3. Primary: congenital or acquired
24
Q

Structural HD/HF causing arr

A

Remodelling of heart

Neurohormonal: symp/parasymp, RAAS, Endothelin

Inflamm mediators and FR’s

Hypoxia: atrial fibrillation, in CHF ventric arr are seen

25
Q

Systemic illnesses as cause of arr

A

Hypoxia, veg tone, temp, electrolytes (Na and K), drugs and toxins

  • Kidney failure, obstruction of urethra (electrolyte disturbances?)
  • Addisons
  • Digoxin OD
  • Anaesth!!!!
  • Sepsis, trauma, hypovolaemic shock
  • Splenic tumour/torsion
  • Gastric torsion
  • Brain/SC injury
  • Pancreatitis
  • Ileus
26
Q

Congenital/ acquired i.e primary causes of arr

A

Channelopathies

Fibrosis, infarcts, amyloidosis

Boxer/bulldog/cat: arrhythmogenic cardiomyopathy- hyper or hypothyreoisis

Mini shnauzer and westie: SSS

Cocker spaniel: AV block

Lab, Boxer: Wolf Parkinson White syndrome- AV acc pathways

27
Q

Consequences of arr

A

Mostly none!

Weakness and syncope if there is interference with the HR

Ventric or brady may result in sudden death

Worsening of already exisitng HF

Bradyarr can cause HF or tachiocariomyopathy (dont know how it would tho?)

May damage the myocard– dilated cardiomyopathy

28
Q

Treatment of arr

A

first must DIAGNOSE!!! via eCG

Cardiac vs extracradiac

No treatment if no signs or haemodynamic changes

Remember that most antiarr are proarr

29
Q

treatable vs non treatable

A

Treatable: tachy/brady, supraventric and ventric

Usually we don’t treat:

  • atrial or ventric infrequent extrasystoles
  • Slow idioventricular or junctionsl rhythms
  • Lone atrial fibrillation
  • 1st/2nd degree AV blocks
  • BBB’s
  • Intraventricular blocks
  • Ventric arr caused by extracardiac cause
30
Q

How to treat the arr

A
  1. Treat the cause! e.g if CHF give diuretics, O2, Pimobendan
  2. By Phys methods! Ocular pressire/vagal maneuver- to induce a high vagal tone to overcome the symp tone. Usually in combo with drugs

Carotis massage, chest thump

  1. Drugs
  2. Artificial pacemaker
  3. Electric cardioversion
  4. Radiofrequency catheter ablation
  5. External defibrillators
31
Q

Using catheter mapping and ablation to treat atrial flutter

A

Occurs when there is re-entry into either the R or L atrium, the AV node tries to filter it out!!

Catheter places in the isthmus btw the tricuspid valve and the eustacian valve of the IVC

There are multiple pairs of electrodes on the catheter - can locate the circuit when the position correlates with conduction!

Heat and E is used to destroy the piece of muscle- no conducting ability anymore!

32
Q

Classes of anti-arr drugs according to the Vaughan-Williams classification

A
  1. Na channel blockers (membrane stabilizers)
  2. Beta blockers
  3. K channels blockers- delay repol
  4. Ca channel blockers
  5. Digoxin
  6. Atropine
33
Q

Na channel blockers

A

Reduce slope of phase O and reduce peak of AP

Works on cells that use Na for depol ie the atrial and ventric working and purkinje but not on SA or AV nodes

treat VENTRIC ARR!!

They delay depol and shorten repol

SE’s: hypoT, convulsions, decr liver metab

Will not work if there is hypokalaemia

34
Q

Na channel blockers: 1a

A

Procainamide

  • SVT (bypass tract)
  • Ventric arr
35
Q

Na channel blockers: 1b

A

Lidocaine and mexiletin

  • Ventric arr
  • (some SVT)

Rapid binding and dissociation

Refractory channels

Ischaemic areas

Usually dilate vessels therefore would decr BP

SE: convulsions

36
Q

Na channel blockers

A

Flecainide and Propafenon

-SVT- bypass tract, atrial flutter!

Slow binding and dissociation

37
Q

Beta blockers

A

Used to treat supraventric arr (they slow the HR0 and ventric arr (in combo)

Block the symp discharge to the heart and therefore slow impulse conduction in the AV node

(-) ino, chrono, bathmo, dromo

38
Q

Beta blockers: 1st gen

A

Non-selective

Propranolol

39
Q

Beta blockers: 2nd gen

A

Selective beta 1: Atenolol and Metoprolol

40
Q

3rd gen beta blockers

A

Carvedilol and bucindolol

Non-selective

aplha blockade

Antiox

41
Q

Repolarization delaying drugs- K channel blockers

A

Amiodarone and Sotalol

Have multiple class effect (I, II, III and IV for amiodarone)

Prolong AP and therefore refractory state (are good for reentry?)

Treat both atrial and ventric arr

42
Q

Calcium channel blockers

A

Dihydropyrimidines: Amlopdipine

Used to treat hyperT as it dilates the vessles. Used at the end of HF

Non-dihydropyrimidines: Verapamil and Diltiazem

Slow AV conduction

Heart>vessels

Cardiac specific: verapamil>diltiazem>amlodipine

Treat: SVT arr! they decr the ventric rate in atrial fibrill

(-) ino: verapamil>diltiazem

If OD: give IV calcium

43
Q

Digoxin

A

decr symp and incr parasymp tone

Restore baroreceptor function

(+) ino- mild

Not IV- sympathomimetic effect! maybe proarr

Treats: SVT by decr the speed of AV conduction

44
Q

Atropine response test

A

Record baseline eCG

Admin 0.04mg/kgbw of atropine SC

Wait for 30 mins

Record eCG for min of 2 mins

Result: dogs with vagally mediated bradycard will have sinus tachycard>140 bpm (i.e parasymp induced brady)

Some dogs with sinus node disease or patho AV blocks will aslo respond to this test

45
Q

Protocol for a new arr case

A

Diagnose with eCG

Exclude HD

Full work up- include electrolytes

Atropine responce test

  1. O2
  2. Sympto: fluids and diuretics
  3. treat the arr
  4. treat the cause if you know it??
  5. find out if its cardiac (phys, echo, BP) or extracardiac (general parameters, electrolytes, Lyme?)
  6. Imaging of abd and thorax
46
Q

Case study of 10yr old male boxer

A

Syncope

Detected arr during phys

Echo was normal

Labs: LOW BG

Abd US: focal lesion in the pancreas

Diagnosis: INSULINOMA! i.e a severe systemic disease- mind immediately jumps to the fact that boxers are predisposed to R ventric exntrasystole

47
Q
A

SAM 2 (12 decks)

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