Download Arrhythmias

Arrhythmias
Cardiovascular course 4th year Pathophysiology
Arrhythmias - Definition and Causes
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Abnormal rhythm of the heart
Causes
1.
Abnormal rhythmicity of the pacemaker (tachycardia, bradycardia)
2.
Shift of the pacemaker to another place in the heart (junctional.
Idioventricular rhythms)
3.
Block of different parts of the conducting system (impulse conduction
blocks)
4.
Abnormal pathway of impulses transmission (WPW syndrome)
5.
Spontaneous generation of impulses in atrias or ventricles (premature
beats, paroxysmal tachycardia, fibrillation, flutter)
6.
Ionic dysbalance (changes of depolarisation, repolarisation)
Mechanisms of Cardiac Arrhythmias
Mechanisms of bradycardias
Mechanisms generating tachycardias
• Accelerated automaticity
• Triggered activity
• Re-entry
Abnormal Sinus Rhythms
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abnormal rhythmicity of the pacemaker
 Tachycardia
 Bradycardia
• Extrinsic causes
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Intrinsic causes
Impulse Conduction Block
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Sinoatrial block
Sinus Arrest
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Atrioventricular block
block between atrias and ventricles
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Interventricular block ( RBBB or LBBB)
impulses fail to reach part of the heart during heart cycle
Types of AV Blocks
1st degree
2nd degree block: partial block
Mobitz I
Mobitz I
3rd degree block: complete heart block
Right and Left Bundle Branch Blocks
Right bundle branch block (RBBB)
Left bundle branch block (LBBB)
Preexcitation Syndrome – Wolff-Parkinson-White
• AV conduction through the accessory pathway is faster than through
the AV node
Premature Beats - Extrasystoles
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the heart beats before the time of normal contraction.
Types:
• Premature atrial contraction
• Premature junctional contraction
• Premature ventricular contraction
Paroxysmal Tachycardia
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rapid rhythmical discharge of impulses that spread throughout the heart
caused by re-entrant circuitry movement
Types of paroxysmal tachycardia
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Paroxysmal supraventricular tachycardia (atrial, junctional)
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Paroxysmal ventricular tachycardia
Fibrillation
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results from cardiac impulses that have gone chaotically within the muscle
known as a phenomenon of re-entry:
Types:
• atrial
• ventricular
Atrial Flutter
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atrial focus activates the atria at a rate of around 300 times per minute
A Systematic Approach to Reading the 12-lead ECG
Check these data (patient’s name, birthday, and identification number; date and time of tracing) on the ECG to make
sure:
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Review the patient’s medical history, physical and laboratory findings, diagnosis, and indication of the ECG
examination. You still should review all aspects of the ECG before drawing your conclusion.
Make old tracings available for comparison. In medical practice, changes in findings over time are as important
as the presence or absence of findings at any discrete moment in time.
Check heart rate.
Check rhythm:
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Primary rhythm: supraventricular (sinus, atrial, junctional) or ventricular in origin.
Superimposed abnormalities (escape or premature beats).
Check heart blocks.
Check QRS axis.
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Enlargement of right and left ventricle
Bundle braches blocks
Check signs of clinical abnormalities:
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It belongs to the patient you are reviewing.
It was obtained on the day and time you requested the examination.
Right and left atrial abnormalities.
Right and left ventricular hypertrophy.
Right and left bundle branch block.
Acute myocardial infarction.
Electrolyte abnormalities.
Drug effects.
Pulmonary embolism.
Correlate the ECG findings with the patient’s clinical presentation. Treat the patient; not the waveforms.