Arrhythmias Flashcards
What are the 2 shockable rhythms?
• Ventricular tachycardia
• Ventricular fibrillation
What are the 2 non-shockable rhythms?
• Pulseless electrical activity (all electrical activity except VF/VT, including sinus rhythm without a pulse)
• Asystole (no significant electrical activity)
How is ventricular tachycardia managed?
IV Amiodarone
How are polymorphic ventricular tachycardia’s managed?
IV magnesium
What are 3 main causes of bradycardia?
○ Medications (e.g., beta blockers)
○ Heart block
○ Sick sinus syndrome
What is sick sinus syndrome?
• Sick sinus syndrome encompasses many conditions that cause dysfunction in the sinoatrial node.
What often causes sick sinus syndrome?
○ It is often caused by idiopathic degenerative fibrosis of the sinoatrial node.
What 4 things can increase a persons risk of asystole?
§ Mobitz type 2
§ Third-degree heart block (complete heart block)
§ Previous asystole
§ Ventricular pauses longer than 3 seconds
What is the 1st line management in patients at risk of asystole?
IV atropine
How does atropine work?
• Atropine is an antimuscarinic medication and works by inhibiting the parasympathetic nervous system.
What are some side effects of atropine? (4)
Why are they caused?
Pupil dilation
Dry mouth
Urinary retention
Constipation
As parasympathetic nervous system is inhibited
What is the management of atrial flutter? (2)
Anticoagulantion based on chadvasc score
Radio frequency ablation of reentrant rhythm
What is classed as a prolonged QT interval in men? And in women?
○ > 440ms in men
○ > 460ms in women
What does a prolonged QT interval mean is happening in the heart?
prolonged repolarisation of the heart muscle cells (myocytes) after a contraction.
What is the mechanism of torsardes de pointes?
Long QT interval
Spontaneous depolarisation if repolarisation is taking a long time
• These abnormal spontaneous depolarisations before repolarisation are known as afterdepolarisations.
• These afterdepolarisations spread throughout the ventricles, causing a contraction before proper repolarisation.
• When this leads to recurrent contractions without normal repolarisation, it is called torsades de pointes.
What class of tachycardia is torsades de pointes?
Polymorphic ventricular tachycardia
What can torsades de pointes turn into?
Can spontaneously resolve
Can progress to VT which can lead to cardiac arrest
What is the management of QT prolongation? (4)
• Stopping and avoiding medications that prolong the QT interval
• Correcting electrolyte disturbances
• Beta blockers (not sotalol)
Pacemakers or implantable cardioverter defibrillators
What are some causes of QT prolongation? (3)
• Long QT syndrome (an inherited condition)
• Medications, such as antipsychotics, citalopram, flecainide, sotalol, amiodarone and macrolide antibiotics
Electrolyte imbalances, such as hypokalaemia, hypomagnesaemia and hypocalcaemia
What is the acute management of torsardes de pointes? (3)
• Correcting the underlying cause (e.g., electrolyte disturbances or medications)
• Magnesium infusion (even if they have normal serum magnesium)
Defibrillation if ventricular tachycardia occurs
What is bigeminy?
• Bigeminy refers to when every other beat is a ventricular ectopic. The ECG shows a normal beat (with a P wave, QRS complex and T wave), followed immediately by an ectopic beat, then a normal beat, then an ectopic, and so on.
What is the management of ventricular ectopics? (3)
• Reassurance and no treatment in otherwise healthy people with infrequent ectopics
• Seeking specialist advice in patients with underlying heart disease, frequent or concerning symptoms (e.g., chest pain or syncope), or a family history of heart disease or sudden death
• Beta blockers are sometimes used to manage symptoms
What is first degree heart block?
where there is delayed conduction through the atrioventricular node.
○ Despite this, every atrial impulse leads to a ventricular contraction, meaning every P wave is followed by a QRS complex.
○ On an ECG, first-degree heart block presents as a PR interval greater than 0.2 seconds (5 small or 1 big square).
How long is PR prolongation in first degree heart block?
PR interval greater than 0.2 seconds (5 small or 1 big square).
What is second degree heart block?
where some atrial impulses do not make it through the atrioventricular node to the ventricles.
There are instances where P waves are not followed by QRS complexes
What are the 2 types of second degree heart block and what are they?
i. Mobitz type 1 (Wenckebach phenomenon) is where the conduction through the atrioventricular node takes progressively longer until it finally fails, after which it resets, and the cycle restarts.
ii. Mobitz type 2 is where there is intermittent failure of conduction through the atrioventricular node, with an absence of QRS complexes following P waves.
What ecg changes are seen in mobitz type 1?
□ On an ECG, there is an increasing PR interval until a P wave is not followed by a QRS complex.
The PR interval then returns to normal, and the cycle repeats itself
What are the ecg changes in mobitz type 2?
□ There is usually a set ratio of P waves to QRS complexes, for example, three P waves for each QRS complex (3:1 block).
□ The PR interval remains normal.
What’s the main risk with mobitz type 2?
Asystole
What is third degree heart block?
○ There is no observable relationship between the P waves and QRS complexes.
What is the main risk with third degree heart block?
Asystole
What drug is contraindicated in VT?
Verapamil
