Miscellaneous Flashcards
Premature ventricular contraction
- Common
- Symptoms
- Majority asymptomatic
- Heat palpitations, dizziness
- ECG Findings
- Absent p wave, QRS > 120ms, bizare QRS appearance, T wave opposite direction to main QRS vector.
- Fully compensatory pause (PP interval is twice/thrice the sinus PP interval.
- Often occur in repeating patterns.
- Bigeminy (Every second beat is PVC)
- Trigeminy (Every third beat is a PVC)
- Three PVC in a row is identified as non-sustained VT.
Management - If low burden of PBC (< 10% of contractions and mild symptoms) don’t treat
- If symptomatic
- Reduced potential triggers
- EtOH, Caffeine, illicit drugs, thyroid disease, electrolyte disturbances
- 1st line - beta blocker or non-dihydropyridine Ca channel blocker
- Catheter ablation.
- Reduced potential triggers
First Degree Heart Block
Delayed conduction from Atrium to ventricle.
Causes
- Increased vagal tone (Endurance athletes)
- Underlying cardiac conditions.
- Medications.
- Rx - Nil if no symptoms.
- ECG
- PR > 200m.
Second Degree Heat Block
- Intermittent atrial conduction to the ventricle.
- Excitation fails to pass through AV node or bundle of HIS.
- ECG findings
- Mobitz 1 - PR prolongation with non-conduction of QRS complex.
- Mobitz - No PR prolongation but non-conduction of QRS complex.
Causes - Mobitz 1 - Functional suppression of AV conduction due to drugs or reversible ischaemia.
- Mobitz 2 - Structural damage to conducting system (Infarction, fibrosis, necrosis)
Third Degree Heart Block
Atrial contraction is normal but no beats are conducted to the ventricle.
Causes
- Inferior MI
- AV-Nodal blocking drugs (Ca-Ch Blockers, B-blockers, Digoxin)
ECG
- No relationship between P waves and QRS complexes
- Differing atrial and ventricular rate.
Treatment if sympomatic bradycardia
- Atropine 0.5mg IV stat, repeat in 15 mins
- Cardiac pacing
Atrial flutter
Rapid, regular atrial depolarisations at a characteristic rate of 300bpm with ventricular rate of 150bpm
ECG
- Sw-tooth pattern of inverted flutter waves most easily identified in ii, iii and avF
Supraventricular Tachycardia
Any tachy dysrhythmia arising above bundle of his.
- ECG
- Regular tachycardia (140-280bpm), narrow QRS complexes. P waves likely not visible.
- Rx
- Vagal stimulation
- Adenosine 6mg IV stat, increasing doses if ineffective after 2-3 mins up to 18mg IV stat
- Prophylaxis post
- Beta blocker
- Metoprolol tartrate 25mg PO BD, Sotalol 80mg PO BD
- Verapamil MR 180mg PO OD
- Beta blocker
Left ventricular Hypertrophy
Causes
- Hypertension, Aortic Stenosis
ECG
- Increased QRS voltage (Largest R wave + largest S wave in precordial leads > 45mm, Increased QRS Duration, left axis deviation,
Management of Acute Bradyarrhthmias
Check underlying causes
- Raised ICP
- IHD
- Hyperkalaemia
- Hypothermia
Emergency management
- Airway, breathing, oxygen, 12-lead ecg, monitor vitals, establish IV access, prepare for transcutaneous pacing
Treat with atropine/pacing if
- Signs of poor perfusion (hypotension, syncope, altered conscious state, ischaemic chest pain, heart failure
Atropine 0.5mg IV repeat after 3-5 minutes up to a maximum of 3mg.
Wolf Parkinson White
ECG
- Short PR interval (< 120ms 3 small squares)
- Broad QRS complex with slurred upstroke (Delta wave)
- Tall R waves and inverted T waves in V1-3 mimicking RVH (No underlying RVH just looks similar)
LBBB
ECG
- QRS > 120ms
- WiLLiaM
- Dominant S wave in V1
- Monophasic R waves in lateral leads (I, aVL, V5-V6)
Note: Cannot comment on possibility of LVH easily if presence of LBBB. Cannot identify ischaemia with LBBB.
RBBB
ECG
- QRS > 120ms
- MoRRoW
- RSR pattern in V1
- Wide, slurred S wave in V6
Associated ST depression and TWI in V1-V3
Acute management of sustained Ventricular Tachycardia
Unstable? DC Cardioversion
Stable?
- Amiodarone 300mg IVIF 10-20mins -> 900mg IVIF 24 hours
- 2nd line - Lidocaine infusion
Management of non-sustained Ventricular Tachycardia
NSVT - VT lasting 3 or more beats but less than 30 seconds.
- Treat if prolonged episodes with haemodynamic compromise.
1st line - Beta blockers
-Atenolol 25mg PO OD
- Metoprolol Tartrate 25mg PO BD
Betablockers contraindicated?
- Flecainide 50mg PO BD
- Verapamil MR 180mg PO OD.
LVH
ECG
- Voltage criteria - SV2 and RV6 > 35mm (7 large squares)
- Almost identical appearance of LBBB but with above voltage criteria seen
Pathological Q waves
Usually indicate current or prior myocardial infarction
Voltage criteria
- > 40ms (1mm) wide
- > 2mm deep
- > 25% of QRS complex
