Perioperative Cardiac Dysrrhythmias Presentation Final

8/13/2019 Perioperative Cardiac Dysrrhythmias Presentation Final

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PERIOPERATIVE CARDIAC

DYSRRHYTHMIAS

Agya Boakye Prempeh


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FORMAT

INTRODUCTION

ANATOMY OF THE CARDIAC CONDUCTION SYSTEM

NORMAL CARDIAC ELECTROPHYSIOLOGY

MECHANISM

RISK FACTORS

MANAGEMENT

ANAESTHETIC CONSIDERATION

CONCLUSION


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INTRODUCTION

DEFINITION Abnormal cardiac rate or rhythm

- Asymptomatic/Symptomatic/lethal

INCIDENCE Most frequent perioperative cardiovascular

abnormality

- In a multicenter study with 17,201 patients

70.2% of cases had dysrrhythmias duringcardiac or noncardiac surgery combined,1.6% were treated

>90% of cases had dysrrhythmias during cardiac surgery

alone


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ANATOMY OF THE CARDIAC

CONDUCTION SYSTEM


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NORMAL CARDIAC

ELECTROPHYSIOLOGY

SINOATRIAL NODE VENTRICULAR MUSCLE

4

0

1

2

3

4


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MECHANISM OF CARDIAC

DYSRRHYTHMIAS

There are two(2) broad groups:

A) Disorders of impulse initiation

B) Disorders of impulse conduction


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DISORDERS OF IMPULSE INITIATION

This also grouped into two(2)

1) Alteration of Automaticity

2) Triggered Activity


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ALTERATION OF AUTOMATICITY

A

Maximum diastolic potential(K+ conductance)

- Ach eg. Vagal manuevres

- Hypoxia/Hypokalaemia

B Slope of phase 4 (Na+ leak)

-Catecholamines eg. pain

- Ach

C Threshold of Action Potential

AB

C

Defn: Alteration of spontaneous phase 4 depolarisation

Origin: SA node / Ectopic Focus(nonpacemaker attributes)


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TRIGGERED ACTIVITY

Defn: Action Potential(AP) which initiates membrane

potential oscillations(afterdepolarisation)

during late phase 2 or Phase 3 or Phase 4.

When the membrane potential oscillations reach

threshold potential a new AP is formed.

aetiology : intracellular calcium overload( Digitalis toxicity, long QT syndrome)


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DISORDERS OF IMPULSE CONDUCTION

This is grouped into two(2)

1) Conduction blocks along normal pathway

2) Abnormal pathway conduction


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CONDUCTION BLOCKS ALONG NORMAL PATHWAY

Defn: There is failure of successful conduction of

impulse along normal pathway.

Aetiology : - Reduction in tissue excitability

- Abnormalities of gap junctions btn cells

Site of Block : a) SA node

b) AV node

c) Intraventricular(BBB) doesnt slow heart


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ABNORMAL PATHWAY CONDUCTION

Defn: Conduction of an impulse along an abnormal tract

Tract maybe anatomical-(WPW) or functional-(SVTA)

3 Conditions to be satisfied


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RISK FACTORS FOR DEVELOPING

CARDIAC DYSRRHYTHMIAS

This can be grouped into three(3)

- Patient related factors

- Anaesthesia related factors

- Surgery related factors


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PATIENT RELATED FACTORS

1) CVS abnormality Preexisting cardiac disease eg. MI

- Pulmonary/Coronary thrombosis

2) Respiratory abnormality : Tension pneumothorax

3) CNS abnormality : Intracranial diseases esp. SAH may

show ECG abnormalities such as

Q waves, ST segment changes, QT

interval changes, U waves

4) Aging Degenerative changes in atrial anatomy


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ANAESTHESIA RELATED FACTORS

Technique GA / CNAB

Direct laryngoscopy and tracheal intubation -commonest cause

Hypoxia/Hypercarbia/Acidosis

Hypothermia/Hyperthermia

Hypovolaemia

Central venous cannulation

Pressure from fingers can stimulate carotidsinus reflexes during jugular venous cannul.

- Excessive insertion of catheter into rightatrium


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SURGERY RELATED FACTORS

1) General surgery

Traction on peritoneum (bradyarrhythmias)

2) Dental surgery Profound stimulation of both

parasympathetic and sympathetic

nervous systems

3) Cardiac surgery Retraction of beating heart

- Taking sutures over the right atrium

- Damage to conduction pathway by

surgical incision- Immediate period following release of

aortic cross clamp


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MANAGEMENT OF CARDIAC

DYSRRHYTHMIAS

Dependent on whether bradydysrrhythmia/tachydysrrhythmia

BRADYDYSRRHYTHMIAS

Defn: Heart rate < 60bpm and inadequate for clinical

condition

Origin SA node (examples)/ AV node(examples)


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MANAGEMENT OF BRADYDYSRRHYTHMIAS


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TACHYDYSRRHYTHMIAS

Defn: Heart rate > 100 bpm

Classification based on:

1. Appearance of QRS Complexes Narrow(0.12 sec)

2. Rhythm Regular/ irregular

3. Origin SA node/ atria/ AV node/ Ventricle


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MANAGEMENT OF TACHYDYSRRHYTHMIAS


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ANAESTHETIC CONSIDERATION

ECG monitoring All patients

- Lead 11 and V5

Routine measures intraop Airway patent eg. SAB

- Breathing: Adequate

ventilation andoxygenation

- Cardiac history/pathology

reevaluation

- Depth of anaesthesia adequate

- Electrolytes and ABGs optimum- Temperature

Specific therapy depends on type of dysrrhythmia


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CONCLUSION

Most perioperative dysrrhythmias are benign without significant

haemodynamic consequences.

However symptomatic patients whose dysrrhythmias can evolve to life-

threatening ones should be treated with anti-dysrrhythmic drugs or

electrotherapy promptly.

Finally, anti-dysrrhythmic drugs can also cause dysrrhythmias and often

times the anaesthetist in an attempt to treat perioperative dysrrhythmias

causes iatrogenesis and as such the knowledge of the physiology of cardiac

rhythm, pathogenesis of dysrrhythmias, anaesthetic pharmacology and riskto benefit of anti-dysrrhythmic drugs are mandatory.


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ACKNOWLEDGEMENT

Dr Baddoo

Dr Djagbletey


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THANK YOU

Documents

Perioperative Cardiac Dysrrhythmias Presentation Final