Asymptomatic arrhythmias and those which do not jeopardize haemodynamics, e.g. most AES and occasional VES, first degree AV block, bundle branch block, etc. in an otherwise normal heart, do not require antiarrhythmic treatment.
CHOICE OF ANTIARRHYTHMICS
Asymptomatic arrhythmias and those which do not jeopardize
haemodynamics, e.g. most AES and occasional VES, first degree AV block, bundle
branch block, etc. in an otherwise normal heart, do not require antiarrhythmic
treatment. Chronic prophylactic therapy with class I and class IV
antiarrhythmics does not appear to afford survival benefit, except in few
selected cases. On the other hand, vigorous therapy is indicated when:
·
Arrhythmia is life-threatening, e.g. sustained
VT, torsades de pointes, VF.
·
Arrhythmia is causing hypotension, breathlessness
or cardiac failure.
·
Palpitation is marked, e.g. in PSVT, sustained
VT, AF, torsades de pointes.
· When simple arrhythmia may lead to more
serious ones, e.g. after MI (warning arrhythmias).
In the above
situations antiarrhythmics are mostly needed for short periods. The choice of an
antiarrhythmic in a patient depends on:
·
ECG diagnosis
·
Possible mechanism underlying the arrhythmia
·
Mechanism of action and range of antiarrhythmic
activity of the drug Pharmacokinetic profile of the drug
·
Haemodynamic effects of the drug
The aim is to improve
cardiovascular function either by restoring sinus rhythm, or by controlling
ventricular rate, or by conversion to a more desirable pattern of electrical
and mechanical activity.
Despite extensive
investigation, choice of an antiarrhythmic is still largely empirical. Current
guidelines are summarised in Table 38.2.
Related Topics
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