Authored by Hilary Denis Solomons
A range of cardiotoxic abnormalities occur in about one third
to one half of patients with systemic envenomation, These effects
include atrial tachycardia, ventricular extrasystoles, T-wave
inversions, ST-T wave changes and less frequently, bundle branch
block. Increased autonomic stimulation caused by increased vagal
effects on the heart and sympathetic stimulation are the probable
cause of these effects. Hypertension is common and occurs early in
response to sympathetic stimulation. Hypotension is less common,
occurs with the development of severe envenomation, and often
requires intervention with vasopressors and fluid resuscitation.
Many factors are at play in the development of hypotension,
with cholinergic stimulation causing vasodilatation, fluid loss
and myocardial depression. Cardiac dysfunction resulting from
catecholamine-induced myocarditis and myocardial ischaemia
complicates severe envenomation. This complication may result in
pulmonary oedema and cardiogenic shock!
In cases of severe envenomation ECG, cardiac enzymes and
echocardiography may be of value. This will be guided by the
degree of envenomation and the facilities available. Dobutamine
treats cardiogenic shock and decreases in cardiac output resulting
from elevated catecholamines and myocardial injury. Nitroglycerine
acts as a vasodilator for treatment of pulmonary oedema;
decreases preload and afterload through arteriolar dilatation and
venodilation. Atropine may also be used. Scorpion stings occur
worldwide and are of clinical importance as they may cause local
effects or more systemic neurotoxic and cardiovascular toxic effects.
The specific treatment is antivenom combined with symptomatic
and supportive treatment, including prazosin and dobutamine
in patients with cardiovascular effects and benzodiazepines in
neuromuscular involvement. The stinger of the scorpion releases
many toxins (mostly alpha toxins.)
These toxins act on potassium and calcium channels, but these
toxins appear to be less important in human envenomation!
None.
No conflicts of interest
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