Download PERI – ARREST ARRHYTHMIAS

PERI – ARREST ARRHYTHMIAS
Anu Roy
BACKGROUND
The term ‘peri – arrest arrhythmias’ are used to describe cardiac rhythm
disorders that may precede cardiac arrest or follow initial resuscitation from a
cardiac arrest. Effective treatment of such arrhythmias may prevent cardiac
arrest.
A clear trace showing ‘P’ waves and ‘QRS’ complexes is mandatory for
diagnosis. A 12 - lead ECG is essential for the management of tachycardias
associated with a broad QRS complex. When the mechanism of a Broad
Complex Tachycardia cannot be determined regard it as VT (ventricular
tachycardia ), especially in the clinical context of ischaemic heart disease.
PRINCIPLES OF TREATMENT
It is important to treat the patient and not the ECG. The two basic questions
are :
1. How is the patient?
2. What is the arrhythmia?
Adverse signs or symptoms dictate the appropriate treatment for most
arrhythmias. They are -
•
•
•
Clinical evidence of low cardiac output
pallor, sweating, cold extremities, impaired consciousness, hypotension.
Excessive tachycardia or bradycardia
Heart failure
CLASSIFICATION OF THE PERIARREST ARRTHTHMIAS
1. BRADYCARDIA
A bradycardia is defined as a ventricular rate below 60 beats / min. It is also
important to classify a bradycardia as absolute (< 40 beats / min) or relative,
when the heart rate is inappropriately slow for his or her haemodynamic state.
2. BROAD COMPLEX TACHYCARDIA
In the context of resuscitation, a broad complex tachycardia will almost
invariably be ventricular in origin. If there is no palpable pulse, the patient
should be treated as for ventricular fibrillation
3. NARROW COMPLEX TACHYCARDIA
Supraventricular in origin. Can be a trigger for ventricular fibrillation in
vulnerable patients. Atrial fibrillation, on the other hand, occurs commonly in
the early period after resuscitation.
ALGORITHMS.
BRADYCARDIA
YES
Adverse signs ?
*Systolic BP < 90 mmHg
*Heart rate < 40 beats / min
*Ventricular arrhythmias requiring
suppression
*Heart failure
NO
Atropine
500mcg i.v.
initially to maxm 3 mg
Satisfactory
Response ?
YES
NO
NO
YES
Risk of asystole ?
*Recent asystole
*Mobitz II AV block
*Complete heart block
with broad QRS
*Ventricular pause > 3 secs
NO
Interim measures:
*Atropine 500mcg IV
*External pacing
*Adrenaline IV 2 – 10 mcg / min
* Seek expert help (arrange transvenous pacing)
Observe
BROAD COMPLEX TACHYCARDIA
Pulse ?
NO
Use VF protocol
YES
NO
Adverse signs ?
*Systolic BP < 90mmHg
*Chest pain
*Heart failure
*Rate > 150 beats / min
YES
Seek
Expert
Help
Synchronised DC
If potassium known to be low
shock
( see panel
)
J; 360 J
100 J; 200
or equivalent biphasic
energy
>> Amiodarone 150 mg IV
over 10 min
to
or
>>Lidocaine i.v. 50 mg over
2 min repeated every 5 min
to a maximum dose of 200 mg
i.v.
min
**give potassium chloride up
to 60 mmol, maximum rate
30 mmol / hr
**Give magnesium sulphate i.v.
5 ml 50 % in 30 min.
Seek expert help
Synchronised DC shock
cardioversion
100 J; 200 J; 360 J
or appropriate biphasic energy
If necessary, further amiodarone 150 mg
i.v. over 10 min, then 300 mg over 1 hr & rpt shock
If potassium known
be low, see panel
> >Amiodarone 150 mg
over 10
Further
if necessary
For refractory cases consider additional
pharmacological agents : amiodarone,
lidocaine, procainamide or sotalol;
**Or overdrive pacing
Caution: drug induced myocardial
depression
THE ALGORITHMS (continued )
 Narrow complex tachycardia
( Presumed supraventricular tachycardia )
NARROW
COMPLEX
TACHYCARDIA
Pulseless ( heart rate usually
> 250 beats / min)
Atrial
fibrillation
Synchronised DC shock
100 J; 200 J; 360 J
below*
or appropriate biphasic energy
see
Vagal manoeuvres
( caution if possible digitalis toxicity, acute
ischaemia, or presence of carotid bruit for carotid
sinus massage )
Adenosine 6 mg by rapid bolus injection; if
unsuccessful,
follow, if necessary, with up to 3 doses each of 12
mg every
1 – 2 min
Caution with adenosine in known WPW
syndrome
Seek expert help
•
•
•
No•
Adverse signs ?
Systolic BP < 90 mHg
Chest pain
Heart failure
Heart rate > 200 beats /
min
Choose from : Esmolol – 40 mg over 1 min + infusion
4 mg / min ( i.v. injection can be repeated and infusion
increased incrementaly to 12 mg / min ), OR
*Verapamil 5 – 10 mg i.v. OR
*Amiodarone – 300mg i.v. over 1 hr, may
be repeated once if necessary
* Digoxin – maximum dose 500 mcg i.v. over 30 min x 2
Yes
Synchronised DC shock
100 J; 200 J; 360 J
or equivalent biphasic
energy
150 mg iv over 10min,
the 300 mg over 1hr &
rpt shock
* Atrial Fibrillation ( AF )
AF is a chaotic, irregular atrial rhythm at 300 – 600 beats / min. It is common
in the elderly. ECG shows absent ‘P’ waves, irregular ventricular rate. The
appropriate treatment for AF is determined from the patient’s relative risk. It is
helpful if time of onset of AF is known.
Management of AF : seek help of a senior colleague if necessary
 In acute situations, assess the haemodynamic stability of the patient.
 If patient unstable ( heart rate >150 beats/min; ongoing chest pain; critical
perfusion ) – urgent DC cardioversion ( 100J; 200J; 360J ). If cardioversion
fails : Amiodarone 300mg i.v. over 1 hr and if necessary, may be repeated
once. Or Flecainide 100 – 150 mg i.v. over 30 mins.
 Rate control medications include – verapamil / digoxin / diltiazem /
betablockers.
 Treat complications (e.g. heart failure).
 Consider anticoagulation: heparin / warfarin.
NOTES
 DC shock is always given under sedation / general anaesthesia.
 Verapamil is not to be used in patients receiving Betablockers.
 The algorithms include doses based on adult of average body weight and
may need adjustment
 For paroxysms of torsades de pointes, use magnesium (as used in
algorithm above) or overdrive pacing (seek expert help).
 Little harm results if SVT is treated as a ventricular arrhythmia but the
converse error may have serious consequences.
 Pre-excited AF. This is a chaotic, broad complex tachydysrhythmia that
occurs in the context of WPW and related conditions. It may be confused
with V, VF or torsades. It may be treated with Flecainide or DC
cardioversion. It may degenerate into VF if treated with Adenosine,
Lignocaine, Gigoxin or Verapamil
.
Pre-excited atrial fibrillation