A Textbook of Clinical Pharmacology and Therapeutics

222 CARDIAC DYSRHYTHMIAS
Synchronised DC shock*
up to 3 attempts
• Amiodarone 300 mg IV over 10–20
min and repeat shock; followed by;
• Amiodarone 900 mg over 24 h
Irregular
Seek expert help
Possibilities include:
• AF with bundle branch block
treat as for narrow complex
• Pre-excited AF
consider amiodarone
• Polymorphic VT (e.g.
torsades de pointes – give
magnesium 2 g over 10 min)
Unstable
Is QRS regular?
*Attempted electrical cardioversion is
always undertaken under sedation
or general anaesthesia
provides a simple and practical algorithm for the management
of tachydysrhythmias in general.
Catheter ablation therapy is now possible for supraventricular
tachycardias, atrial flutter and fibrillation. Advice from a
consultant cardiac electrophysiologist should be sought
regarding the suitability of a patient for this procedure.
Ventricular dysrhythmias
Ventricular ectopic beats: Electrolyte disturbance, smoking,
alcohol abuse and excessive caffeine consumption should be
sought and corrected if present. The only justification for
treating patients with anti-dysrhythmic drugs in an attempt to
reduce the frequency of ventricular ectopic (VE) beats in a
chronic setting is if the ectopic beats cause intolerable palpitations,
or if they precipitate attacks of more serious tachydysrhythmia
(e.g. ventricular tachycardia or fibrillation). If
palpitations are so unpleasant as to warrant treatment despite
• Support ABCs; give oxygen; cannulate a vein
• Monitor ECG, BP, SpO 2
• Record 12-lead if possible, if not record rhythm strip
• Identify and treat reversible causes
Broad
Is patient stable?
Signs of instability include:
1. Reduced conscious level 2. Chest pain
3. Systolic BP �90 mmHg 4. Heart failure
(Rate related symptoms uncommon at less
than 150 beats min �1 )
Regular
Stable
Is QRS narrow (�0.12 sec)?
If ventricular tachycardia
(or uncertain rhythm):
• Amiodarone 300 mg IV
over 20–60 min; then 900 mg
over 24 h
If previously confirmed SVT
with bundle branch block:
• Give adenosine as for regular
narrow complex tachycardia
Regular
Narrow
• Use vagal manoeuvres
• Adenosine 6 mg rapid IV bolus;
if unsuccessful give 12 mg;
if unsuccessful give futher 12 mg.
• Monitor ECG continuously
Normal sinus rhythm
restored?
Yes
Probable re-entry PSVT:
• Record 12-lead ECG in
sinus rhythm
• If recurs, give adenosine
again & consider choice of
anti-dyshythmic prophylaxis
Is rhythm regular?
Irregular
Irregular narrow complex
tachycardia
Probable atrial fibrillation
Control rate with:
• β-Blocker IV, digoxin IV, or
diltiazem IV
if onset �48 h consider:
• Amiodarone 300 mg IV 20–60
min; then 900 mg over 24 h
Seek expert help
the suspicion that this may shorten rather than prolong life, an
oral class I agent, such as disopyramide, may be considered.
Sotalol with its combination of class II and III actions is an
alternative, although a clinical trial with the D-isomer (which
is mainly responsible for its class III action) showed that this
worsened survival (the ‘SWORD’ trial).
In an acute setting (most commonly the immediate aftermath
of myocardial infarction), treatment to suppress ventricular
ectopic beats may be warranted if these are running
together to form brief recurrent episodes of ventricular tachycardia,
or if frequent ectopic beats are present following cardioversion
from ventricular fibrillation. Lidocaine is used in
such situations and is given as an intravenous bolus, followed
by an infusion in an attempt to reduce the risk of sustained
ventricular tachycardia or ventricular fibrillation.
Ventricular tachycardia: This is covered in Figure 32.3 (management
of tachydysrhythmias). In the longer term, consideration
No
Possible atrial flutter
• Control rate (e.g. β-Blocker)
Figure 32.3: Scheme for the management of tachydysrhythmias. (Adapted with permission from the European Resuscitation Council
Guidelines, 2005).