Arrhythmias Flashcards
narrow complex tachycardia definition
rate >100bpm, QRS complex duration <120ms
DDx narrow c tachy
sinus tachy, SVT, AF, atrial flutter, atrial tachy
management narrow c tachy
DC cardioversion; vagal manoeuvres (valsalva, carotid sinus massage)- increase AV block; adenosine (transient AV block)
Wolff Parkinson White pathophysiology
congenital accessory conduction pathway between atria and ventricles. ventricles contract prematurely
WPW ecg
short PR interval, wide QRS- slurred upstroke/ delta wave, ST-T changes
WPW presentation and treatment
SVT which may be due to AVRT (atrioventricular re-entrant tachycardia); pre excited AF; pre excited atrial flutter. electrophysiology and ablation
broad complex tachycardia definition
rate >100 bpm, QRS >120ms (3 small squares)
DDx broad c tachy
VT, SVT with aberrant conduction
diagnosis broad c tachy
lack of response to adenosine; +ve concordance QRS in chest leads; left axis deviation; 2:1 or 3:1 AV block; fusion or capture beats
what is concordance
QRS complexes all positive or all negative
what are fusion beats
normal beat fuses with VT complex
what are capture beats
normal QRS between abnormal beats
management VF or pulseless VT
DC shock
management stable VT
O2, IV access for tests, ECG, ABG, amiodarone, magnesium sulphate, DC shock, implant ICD (defibrillators), ablation
what is the commonest post MI arrhythmia
ventricular ectopics (also seen in health). suggest electrical instability. consider amiodarone or observe
what are Torsades de Pointes
looks like VF but is VT with varying axis. increased QT interval (a side effect of antiarrhythmics). treat- MgS
what criteria can be used to distinguish SVT from VT
brugada criteria
rate of AF
300-600 bpm
how much does cardiac output drop by in AF and why
10-20% as ventricles aren’t primed reliably by the atria, due to the AV node responding intermittently and so an irregular ventricular rate
causes of AF
heart failure/ischaemia, hypertension, MI, PE, MV disease, pneumonia, hyperthyroidism, caffeine, alcohol, post op, decr K+, decr Mg2+. rare- cardiomyopathy, constrictive pericarditis, endocarditis
symptoms AF
asymptomatic, chest pain, palps, dyspnoea, faintness
signs AF
irregularly irreg pulse, apical pulse rate greater than radial, 1st heart sound variable intensity, signs LVF
tests AF
ecg- absent p waves, irregular QRS. blood- u&e, cardiac enzymes, thyroid function. echo- left atrial enlargement, poor LV function
acute AF treat
O2, U&E, emergency cardioversion; amiodarone. control ventricular rate- verapamil, bisoprolol, 2nd line digoxin, amiodarone. LMWH
chronic AF treat
rate control, rhythm control, anticoagulation
rate control AF
B blocker or rate limiting Ca blocker 1st line. then digoxin then amiodarone.
don’t give B blockers with what drugs and why
diltiazem or verapamil- can cause bradycardia
rhythm control AF
sotalol, amiodarone. fleicanide- pharm cardioversion if no structural heart disease, amiodarone is there is. AV node ablation, pacing etc.
paroxysmal AF
pill in the pocket- sotalol and flecainide.
atrial flutter- ecg
cont atrial depol around 300/min. sawtooth baseline +/- 2:1 AV block.
atrial flutter can be revealed by
carotid sinus massage, IV adenosine- transiently block AV node may unmask flutter waves.
treatment atrial flutter
cardioversion- anticoag before; amiodarone, control rate. b blocker preferred.
anticoag and acute AF
heparin until full risk emboli. warfarin if risk emboli high. no anticoag if stable sinus rhythm
anticoag and chronic AF
warfarin aim for INR 2-3. aspirin if CI to warfarin. dabigatran- direct thrombin inhibitor.
what is sick sinus syndrome
sinus node dysfunction causing brady +- arrest; SA block or SVT alternating with brady/asystole. AF and thromboembolism may occur
bradycardia- if rate is below what, give which drug
<40 bpm, give atropine. if necessary- temp pacing wire, isoprenaline infusion or external cardiac pacing.
