Research Paper - Research on Scorpion Sting

By:
Department of Medicine.
DR. Suvarna N. Patil (M.D) MED.
DR. Sandeep Dhavalikar (M.D) MED.
DR. Anita Khedekar (M.D) CHEST.
[Period : Jan 99 - Jan 2000]

Red scorpion is common in India. Deaths after scorpion sting have been reported from P.H.C. 150 km away from Bombay ( Bawaskar P.H.)

As our hospital is situated in the same area around 220 km from Mumbai, we decided to study the cases who presented with severe left ventricular failure leading to pulmonary oedema. It was found that, those patients who presented with pulmonary oedema, the cause was poor LV function due to regional wall motion abnormality in anteroseptal wall & it was found that after treating these patients with diuretics, digoxin & dobutamine, normal LV function was restored.

Total patients admitted with scorpion sting in one year were 56. Out of which 29 were females & 27 were males.

We studied 10 symptomatic cases of scorpion sting who presented with pulmonary oedema. Echocardiography was done on the day of admission, then on 5th day & on follow up on 15th day. These patients were treated with digoxin, diuretics & dobutamine (as a positive inotropic drug).

After scorpion sting, there is definite regional wall motion abnormality involving IVS & apex (akinetic), which leads to poor LV function & reduction in EF leading to LV failure & pulmonary oedema.

Dobutamine being an inotropic agent was used even in presence of hypotension, as low B.P is due to reduced cardiac output, & increased left ventricular filling pressure. Patients responded well to it.

Envenoming due to Mosebuthus tamulus (the Indian red scorpion) has a case fatality rate of 30% ( Mundle 1961, Gaitone of al 1978)11.

Though our hospital is situated in a rural place facility of ICU and Echocardiography was available, which made us easy to study the cases of scorpion sting with pulmonary oedema. Being a referral centre we aught to see all type of cardiovascular complications in a scorpion sting.

We studied 10 cases who presented to us in pulmonary oedema.

Depends upon the dose of the venom injected & also upon the time lapsed between the bite & treatment received. Average time in our study was 8 hrs. More the time lapsed, severity of symptoms were more.

In our study all 10 cases had sinus tachycardia. Cardiac monitoring was done continuously & we could find no arrhythmia or irregularity in rhythm other than sinus tachycardia during this period.

One patient who died with in first one hour of admission was due to frank pulmonary oedema but no arrhythmia like ventricular flutter or fibrillation was noted.

All 10 cases presenting with pulmonary oedema had hypotension i.e. Systolic BP was 70-80 mm Hg.

2D echo was done serially on day 1, day 5 & day 15. Parasternal long axis, short axis, Apical 4 Chamber & Apical 2 Chamber views along with M-mode were studied. Regional wall motion abnormality was looked for to know the cause of left ventricular failure.

Myocardial function was estimated by segmental approach where intraventricular septum, apex, inferior wall, lateral walls, postero-inferior wall motion was studied. Ejection fraction was calculated visually.

Other M-mode measurements of LV like LV diastolic & systolic diameters, End diastolic & end systolic volumes, stroke volume & fractional shortening, cardiac out put and heart rate were calculated using M-mode echo. Comparison study from 3 readings on 3 different days was done.

In all 10 cases there was akinesia (no movements) in IVS & apex & LV was dilated. LVID(d) was ranging from (5-7 cm). Other walls were spared & there was no RWMA noted in them. Visual EF was 15-20%, which showed poor LV function. One case expired within one hour of admission so follow up echo was not possible.

In remaining 9 cases follow up echo was done on day 5 showed improvement in movements of IVS & IVS became hypokinetic. Visual EF improved to 40-45%. Patients were clinically better. Pulse rate was more than normal i.e. 120-140/min. Blood pressure was 90-100mm/Hg (systolic).

All 9 patients were improved & discharged on day 7. They were called up for follow up echo on day 15, which showed normal study with no RWMA & Visual EF 50-60%.

CPK-MB & SGOT were done on day one, day 3 & day 5. CPK-MB was moderately raised on day one (40-90 iu) and gradually levels declined. SGOT was normal on day one and gradually increased on day 3 to 5.

In two cases having severe pulmonary oedema had non progression of 'R' wave from V1 to V4 & ST elevation in V1-V4 with sinus tachycardia which was co-relating with 2D echo findings.

In remaining 8 cases there were tall 'T' waves with sinus tachycardia. No such changes were seen in inferior leads. Serum 'K+' was normal or low (due to diuretics) in all these cases.

Antiscorpion venom was given to all 10 cases along with prazosin 0.5-1mg on admission & depending upon the severity the dose was repeated.

Out of 10 cases, one expired within one hour of admission, amongst remaining 9 cases, 5 were in frank pulmonary oedema but did not respond to digoxin / diuretics & prazosin. For them control of sinus tachycardia was done by 'CA++' channel blocker ( diltiazem). It was tried in a tablet form which could reduce the heart rate from 180 to 150-140 per min.

But signs of CCF were persistent. So injectable Dobutamine 2.5 -10 (mg/kg/h was used as a positive inotropic agent for abnormally increased ventricular filling pressure for reducing the risk of pulmonary congestion.

As echo findings were similar to what is observed in acute myocardial infarction with LVF dobutamine was used to improve LV function. Angiotensin converting Enzyme inhibitors were not tried due to hypotension.

After given 12hrs continuous drip of dobutamine all five patients responded to it. Echo was repeated on day 5 & showed improvement in EF.

Gradually patients were ambulated & were put on only tablet digoxin & send home. They were called on day 15th for follow up Echo & ECG, were repeated in all 9 patients. Long term follow ups are still going on.

Echocardiography showed distal IVS & apical akinesis with posteroinferior hyperkinesia. Ejection fraction was 15-20% on admission in all 10 patients.

Echo was again repeated on day five, as patients were clinically better on that day, which showed improvement in LV function. IVS & apex were hypokinetic with EF 40%.

Patients were discharged on 7th day & called up for follow up on day 15. EF on follow up was 60% with normal 2D echo study.

All these patients were treated with digoxin, diuretics & they responded well to this line of treatment. 6 patients who had pink frothy sputum with bilateral extensive crepts were put on dobutamine drip (2.5-10mg/kg)for 12 hrs.

Two patients were given ‘ca++’ channel blockers (diltiazem) to control the rate. As blood pressure was all the time low ACEI were not used in these patients.

Our study was our observation & not a real scientific trial. As the mortality is very high with scorpion stings2, we tried our best & used different drugs on trial basis to save the lives of our patients. As we had a facility of 2D Echo & ICU, We could find the nature of cardiotoxicity in these patients. This cardiotoxicity was exactly similar to what we see in anteroseptal myocardial infarction. So treated the patients with digoxin, diuretics & dobutamine.

Scorpion sting occur in tropical & Subtropical regions & are common in rural India4.5 . The heamodynamics & myocardial effects of venom have been reported in animals as well as in humans6,7,8. The red scorpion (Mesobuthos tamulus) was responsible for the sting reported here.

Venom stimulates the automatic nervous system & causes sudden release of catecholomines in to the circulation, which causes transient cholinergic stimulation which leads to vomiting, profuse sweating & bradycardia followed by sustained adrenergic hyper-reactivity (Hypertension, tachycardia & LVF). 9

As we know CCF is frequently caused by defect in myocardial contractility & patients those who have compensated heart disease, arrhythmia's are amongst the most frequent precipitating cause of CCF, as tachycardia reduce the time period , available for ventricular filling.3

CCF due to low out put failure is due to reduced contractility. This acute heart failure in these cases is systolic & there is sudden reduction in cardiac out put which results in systemic hypotension.

In left sided failure fluid localizes up stream to behind the specific cardiac chamber which is initially affected. Here LV is weakened (RWMA). So patients develop dysponea, orthopnoea as a result of pulmonary congestion. Digitalis was given as it stimulates myocardial contractility & improves LV emptying & increases cardiac out put & augments EF. Dobutamine is a synthetic catecholamine which acts on B1, B2,µ receptors & has a potent inotropic action which helps in increasing cardiac out put.

Nefidipine was not tried as all patients had hypotension & define causes reflex tachycardia so it was avoided.

From our study we found that there was specific regional wall akinesia involving apex & IVS which leads to poor LV function leading to pulmonary oedema. On admission digoxin, prazosine & diuretics were given but patients condition went on deteriorating & so positive inotropic drug dobutamine was used to improve the LV function, which gave positive results & out of 10, 9 patients survived.

ACEI can be used to improve EF, but due to hypotension they were avoided. Long term follow up are still going on to know whether there is irreversible myocardial damage.

One study done by Ismail M. Abd.Elasam Ma showed that after injecting IV LD50 Adroctonus crassicauda (Olivier) venom in mice of 0.32%, 0.020 mg /kg showed that the effect on heart atria & anaesthetized rat blood pressure are mediated through stimulation of autonomic nervous system with predominance of sympathetic stimulation & release of tissue catecholamines. ECG showed inferior wall infarction & different degrees of heart block.9

In a study done in Zimbabwe clinical features of 17 patients showed significant parasympathetic nervous system & cardiovascular involvement & it is postulated that the cardiac effects of the toxins are direct & primary, & automatic effect secondary but synergistic, determining the ultimate clinical picture.10

References for echocardiographic study in scorpion sting are not available.

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1)   Total No.  of patients  of  scorpion sting  from  Jan 1999- Dec 1999  were 56.

2)   No. of  Females: 29.

3)   No. of Males: 27.

4)   Mean  Age was: 26.

5)   Mean time  lost at home: 8-7 hours.

6)   Out of  10 patients 4 were  females  & 6 were  males.

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