Tachycardias and Tachyarrhythmias Flashcards
What are the clinical feature of tachycardias
Adverse features
- shock - hypotension, pallor, increased cap refill time
- syncope
- myocardial ischaemia
- cardiac failure - PND, Orthropneoa, bibasal crepitations, raised JVP
Non Adverse features
- Palpitations
- dyspneoa
- Anxiety
How would you initially investigate and manage a tachycardia
A-E assessment Maintain a patent airway Controlled oxygen to maintain sats Bedside obs: HR, RR, BP, sats, temp ECG IV access and take bloods - FBC - U+Es - magnesium - Bone profile - calcium and phosphate - TFTs - LFTs - clotting Fluids if appropiate CXR
How do you differentiate between narrow complex and a broad complex tachycardia
Narrow complex QRS interval of <120ms
Broad complex QRS interval >120ms
How are regular SVTs managed?
A-E, Oxygen, ECG, IV access
Vagal manoeuvres - valsalva and carotid massage
IV adenosine 6mg ->12mg -> 12mg
monitor ECG
SEEK HELP
Electro cardioversion if haemodynamically unstable
In which conditions is adenosine contraindicated in and what should be used instead
Avoided in patients with asthma
Use verapamil instead
Avoid in WPW and patients with denervated hearts also
What are the features of WPW on ECG
Short PR interval
Wide QRS with slurred upstroke ‘delta wave’
Left axis deviation - if right sided accessory pathway
Right axis deviation - if left sided accessory pathway
How is WPW treated
Radiofrequency ablation of pathway
Medical: flecanide, amiodarone
What is wolff parkinson white syndrome
Syndrome caused by a congenital accessory pathway down the bundle of kent between the atria and the ventricles leading to an atrioventicular re-entry tachycardia
How is monomorphic VT managed?
High flow O2
IV access
12 lead ECG
Bloods - FBC,, U+Es, Mg, Ca, cardiac enzymes
ABG - if evidence of pulmonary oedema, reduced conscious level, sepsis
Amiodarone 300mg IV
How is polymorphic VT (torsades de pointes) managed
Magnesium 2g IV over 10 mins
Stop any meds that may prolong the QT interval
Correct electrolyte imbalances
Which drugs may prolong the QT interval
Antipsychotics - chlorpromazine, haloperidol, quetiapine, olanzapine
Antidepressants - Citalopram, Escitalopram, TCA, venlafaxcine
Antibiotics - macrolides (erthromycin and clarithromycin)
Type 1A antiarrhythmics - procainimide
Type 1C - flecainide
Class 3 - sotalol and amiodarone
In ventricular tachycardia when should cardioversion be considered
If adverse signs are present it should be considered before pharmacological intervention
(shock, hypotension, pallor, increased cap refill time, chest pain, syncope, heat failure)
or if amiodarone fails
How are irregular SVT managed
If onset <48hrs - amiodarone 300mg IV over 20-60mins
otherwise control rate with
IV Beta blockers
IV Digoxin
What can precipitate a VT
Metabolic - hypokalaemia, hypomagnesium
Cardiac - IHD, Cardiomyopathy, MI
Drugs - Cocaine
What can precipitate an SVT
Cardiac - IHD
Metabolic - thyrotoxicosis
Drugs - caffeine, alcohol, smoking
What can precipitate an episode of AF
Cardiac - IHD, HTN, mitral valve disease, pericardial disease, Cardiomyopathy
Resp - lung disease
Post operatively
What is the MOA of amiodarone
Blocks potassium channels which inhibits repolarisation and prolongs the action potential
Class 3 antiarrhythmic
What is the CHA2DS2 VASC score and what does it stand for
It is a score predicting whether a patient with AF needs anticoagulation C - congenital heart failure H - hypertension A2 - Age >75 (2points) Age 65-74 (1 point) D - Diabetes mellitus S2 - Prior stroke or TIA (2 points)
Vascular disease
S- Sex - Female
Which scoring system is used to risk assess patients who need anticoagulation
HAS-BLED
H - hypertension - uncontrolled
A - Abnormal renal of liver function
S - Stroke - hx of
B - bleeding, hx of bleeding, tendency to bleed
L - Labile INRs (high, unstable INRs time in therapeutic range <60%)
E - elderly >65years old
D - Drugs that may predispose to bleeding (antiplatelet agents/NSAIDs)
Alcohol use >8 units per week
A score of 3 or more is considere=d high risk
What should be done in ventricular fibrillation or pulseless or unstable VT
asychronised DC shock
What is a common complication of using amiodarone through a peripheral line
Phlebitis
especially if conc is over 2mg/ml
What is a fusion beat
when a normal beat fuses with a VT complex to create an unusual complex
What is a capture beat
a normal QRS between abnormal beats
What is the most common post-MI arrhythmia and what do they suggest
Ventricular ectopics
They suggest electrical instability
Risk if VF if ‘R on T’ pattern is seen (no gap before the T wave)
