Cardio 2 Flashcards
What does the PR interval represent?
Delay in conduction at the AV node
Mx of Mobitz II?
Pacemaker
What infectious disease can cause 3rd degree heart block?
Lyme disease
What medications can cause heart block?
- beta blockers
- CCBs
- adenosine
- amiodarone
- digoxin
What condition can cause congenital heart block?
Neonatal lupus (anti-Ro and anti-La Abs attack the conduction system).
Give some causes of RBBB
1) PE
2) RVH
3) RHF
What is the main ECG feature of BBB?
Widening of the QRS
What condition are those with 1st degree AV block at an increased risk of?
AF
Define preload & afterload
Preload - amount of blood that returns to the heart
Afterload - peripheral resistance
Mechanism of digoxin?
Inhibits Na+/K+ ATPase pump at the cell membrane of the cardiomyocyte.
What is a ‘black triangle’ medication?
Black triangle drugs are medicines that are under intensive monitoring because they are either new to the market or have very limited post-marketing exposure data.
ALL suspected adverse drug reactions (even diarrhoea) must be reported using the Yellow Card scheme.
What is the yellow card scheme?
Has become the standard way to report adverse reactions to medications.
It is run by the Medicines and Healthcare products Regulatory Agency (MHRA).
What should be reported under the yellow card scheme?
1) all suspected adverse drug reactions for new medicines (identified by the black triangle symbol)
2) all suspected adverse drug reactions occurring in children, even if a medicine
What dose of the following drugs is given in peri-arrest rhythms:
1) atropine (in bradycardia)
2) amiodarone (in VT)
3) adenosine (in SVT)
1) 500 micrograms (up to 6x i.e. 3mg)
2) 300mg IV
3) 6mg then 12mg then 18mg
What are the investigations of choice for narcolepsy?
Multiple sleep latency EEG, along with polysomnography.
Common contraindication for adenosine?
Asthma/COPD - as causes bronchospasm
PR interval on an ECG?
From start of P wave to start of QRS complex (i.e. NOT to R)
What falls under ‘risk of asystole’ when mx bradycardia?
1) recent asystole
2) Mobitz type II block
3) complete heart block with broad QRS
4) ventricular pause >3s
What are the 2 options for temporary cardiac pacing in bradycardia?
1) Transcutaneous pacing
2) Transvenous pacing
What are the 3 types of SVT?
1) Paroxysmal
2) AVNRT –> the re-entry point is through the AV node
3) AVRT –> the re-entry point is an accessory pathway (e.g. WPW syndrome)
Give 4 conditions that atrial flutter can be associated with?
1) HTN
2) IHD
3) Cardiomyopathy
4) Thyrotoxicosis
Mx of tachycardia with life threatening features?
1) Synchronised DC cardioversion (up to 3 attempts) - sedation or anaesthesia if conscious
If unsuccessful:
2) Amiodarone 300mg IV over 10-20 mins
3) Repeat synchronised DC shock
Mechanism of adenosine?
Slows cardiac conduction through the AV node
Give some key contraindications for adenosine?
1) Asthma/COPD
2) HF
3) Heart block
4) Hypotension
Give verapamil instead
Mx of atrial flutter?
Similar to AF
1) Rate control w/ beta blockers
2) Treat underlying cause e.g. HTN, thyrotoxicosis
3) Radiofrequency ablation (permanent)
4) Anticoagulate
2 types of VT?
1) Monomorphic i.e. each QRS is identical
2) Polymorphic (torsades de pointes) i.e. each QRS is different
Who does torsades de pointes occur in?
Patinets with a prolonged QR interval:
1) Long QT syndrome (inherited)
2) Medications:
- antipsychotics
- citalopram
- flecainide
- sotalol
- amiodarone
- macrolides
3) Electrolyte disturbances:
- hypokalaemia
- hypomagnesaemia
- hypocalcaemia
Mx of torsades de pointes?
IV magnesium sulphate
Stop causative meds/correct electrolytes
what beta blocker can cause a prolonged QT interval?
sotalol
What 3 electrolyte abnormalities can lead to a long QT interval?
1) Hypokalaemia
2) Hypocalcaemia
3) Hypomagnesaemia
What is monomorphic VT most commonly caused by?
MI
Mx of torsades de pointes?
IV magnesium sulphate
What does a prolonged QT interval represent?
Prolonged repolarisation of the myocytes after a contraction.
What class of medication is atropine?
Antimuscarinic –> inhibits parasympathetic nervous system
Side effects of atropine?
Antimuscarinic:
- dry mouth
- dry eyes
- constipation
- urinary retention
- pupil dilation
What is a key class of Abx that can cause long QT?
Macrolides
Which macrolide carries that greatest risk of QT prolongation?
Erythromycin
What is the QT interval on an ECG?
From beginning of QRS complex to the END of the T wave.
