Download cardiovascular complications of scorpion stings and the effects of

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Articles
CARDIOVASCULAR COMPLICATIONS OF SCORPION
STINGS AND THE EFFECTS OF ANTIVENOM
RAzA M. SOOMRO, MBBS, MSc; JOSEPH J. ANDY, MD; SULAIMAN KONTRACTOR, MRCP; T
AREK M. EL-HADY, MBBCH; OSAMA A. EORES, MBBCH; SRILAKSHMI PARVATHAREOOY,
BSc; KIuSHNAKUMARl GANNI, BSc; NADEEM AHMED, BSe
The study was designed to evaluate (1) the frequency and types of cardiovascular complications
caused by scorpion stings and (2) the effects of cardiovascular morbidity and mortality caused by
changes in antivenom policy instituted in mid-1991 from an optimal treatment of none or 1
ampoule to the current mandatory dosage of five or more ampoules administered at point of first
contact. From January 1992 to December 1995, prospective clinical and echocardiographic
observations were made on 179 of968 cases of scorpion sting admissions who had cardiovascular
complications. A retrospective analysis of deaths and of all cases of scorpion stings treated for
pulmonary edema or cardiopulmonary arrest (among 162 admissions) in the two years preceding
the policy change (January 1990 to December 1991) was also undertaken. Most patients in the
preceding two years had received 0 to 1 ampoule of anti venom. In the prospective study,
cardiovascular complications were observed in 179 (18.5%) cases. Electrocardiographic (ECG)
abnormalities were most frequent (72%) and included sinus tachycardia (56%), tented T-waves
(29%), non-Q infarct pattern (17%), Q-infarct pattern (3%); supraventricular tachycardia; atrial
fibrillation; and second-degree AV block and nodal tachycardia in one patient each.
Echocardiography obtained in 48 cases within 24 h of sting was normal in 23 (48%) but showed
abnormal left ventricular systolic function in 25 (52%), including all 12 patients with pulmonary
edema. Serial echoes in 14 abnormal cases showed significant improvements in ejection fraction
from 36.7:t 14.6% to 58:t 11.4% (P = 0.00002) with corresponding significant changes in fractional
shortening % (P = 0.00033) following therapy. Interventricular septal motion abnormality was
most frequently seen, left ventricular posterior wall motion abnormality was less common, and
global wall motion abnormality was seen only in the more severe cases. There was a reduction in
the incidence of pulmonary edema from 11.1 % to 1.2% (P < 0.001), of cardiorespiratory arrest
from 7.4% to 0.4% (P < 0.001), and cardiac-related deaths from 1.8% to 0% (P < 0.001),
respectively, since the new serotherapy schedule. All cardiovascular changes including ECG and
echocardiographic, congestive heart failure, and pulmonary edema were reversible in survivors.
SCORPION STINGS are a major health problem in
the Middle East, and a common medical problem in
many other countries. 1-4 In Mexico, there are about
300,000 stings with 1000 deaths per year. 1.2 The
national estimate for Saudi Arabia is unknown but it
is known
From the Division of Cardiology, Department of Medicine, King Fabd
Hospital, AI-Saba, Saudi Arabia.
Address reprint requests and correspondence to Dr. Soomro: Division
of Cardiology, Department of Medicine, King Fabd Hospital, P.O. Sox 204,
AI-Saba, Saudi Arabia
Journal of the Saudi Heart Association, Vol. 10, No.1 , 1998
to be a common problem.s.7 At King Fahd Hospital,
in AI-Baha, scorpion stings accounted for 1.1 % of
179,800 total admissions from 1985 to 1995. There
are 650 scorpion species worldwide,I.2 but only 2
species - Leiurus quinquestriatus ("yellow") and
Nebo hierichonticus ("black") are common in the
AI-Baha region of Saudi Arabia.s
Cardiovascular and neurologic complications
account for the most severe morbidity and are the
leading causes of mortality in scorpion stings.9-161
CV COMPLICATIONS OF SCORPION STINGS
3
Mortality is much higher in children than in adults. In intensive care unit. We compared the incidence of
Brazil, deaths due to scorpion stings were 0.8% to 1.4% these two severe complications in 1990 and 1991
among adults, 3% to 5% among school children, and when none or 1 ampoule of antivenom was given with
15% to 20% among very young children. 1
the incidence from 1992 to 1995 when five or more
ampoules of antivenom were given.
Except for the changed policy on anti venom
dosage, the treatment protocol for scorpion stings had
not changed since 1985 in this hospital and the region.
Analgesics were used as indicated. Acutely ill patients
were managed in the intensive care unit. Frusemide,
inotropics, chlorpromazine, and vasodilators were
used as indicated and at the discretion of the treating
physician. We made no attempts to interfere with the
general management of each patient by individual
The present study was physician.
Prior to 1991, there was no consensus on the use of
scorpion anti venom in this hospital and region, and hence
most patients received either none or 1 ampoule of
antivenom. This policy was changed in mid-1991, and all
patients with scorpion stings have since received five or
more ampoules of antivenom (unless they were allergic).
The initial dose was usually given immediately when the
patient presented to the primary health center or hospital.
In a previous communication from this center,
echocardiographic fmdings in scorpion stings had been
documented in children.
14
designed to evaluate echo cardiographic changes, the
frequency of other cardiovascular manifestations of Statistical Analysis
scorpion stings in all patients (children and adults), and
Statistical analysis employed the chi-square
the effects of the new antivenom dose and schedule on methods.
severe cardiovascular morbidity and mortality.
Results
Patients and Methods
The present study was designed in two parts. The first
part was a prospective study of 968 consecutive patients
with scorpion stings admitted to King Fahd Hospital
from January 1992 to December 1995. Complete blood
count, electrolyte, urea and creatinine; cardiac and liver
enzymes; chest x-ray; ECG; blood gas analysis; and
coagulation profiles were done routinely in all admitted
cases and were obtained in all scorpion sting cases with
cardiovascular complications. We attempted to obtain
echocardiographic studies on all patients with severe
myocardial dysfunction, as manifested by pulmonary
edema and ECG changes of Q and non-Q myocardial
infarction patterns within the first 24 h of sting. We also
randomly studied by echocardiography selected
patients with normal ECG and those with milder ECG
changes, such as isolated T -wave changes, within the
first 24 h of sting. Echocardiographic studies were
repeated if the initial studies were abnormal. The second
part of the study was a retrospective analysis of all
cases of pulmonary edema and cardiopulmonary
arrest trom scorpion stings among 162 consecutive cases
of scorpion stings admitted from January 1990 to
December 1991. All cases of pulmonary edema and
cardiopulmonary
arrest
complicating
stings were usually admitted and treated in the
Jownal of the Saudi Heart Association, Vol. 10, No.1, 1998
scorpion
Prospective Observations
Of the 968 cases admitted with scorpion stings,
179 (18.5%) had cardiovascular complications. The
majority of patients with cardiovascular complications
(67%) were below 15 years of age, and the same
proportion were males (Table 1). A total of81 (45.3%)
cases were bitten by yellow scorpions (Leiurus
quinquestriatus), 22 (12.2%) by black scorpions
(Nebo hierichonticus), and 76 (42.5%) by unidentified
scorpions.
The major constitutional symptoms manifested in
the 179 patients included: vomiting (75%), sweating
(67.5%), salivation (40%), priapism (48.3%), and
fever (28%). Associated neurologic manifestations
were observed in 55%, and 85% of these were
younger than 15 years. Abnorrnallaboratory findings
included leucocytosis in 68%, hyperglycemia in 51 %,
elevated creatinine kinase level in 55%, aspartate
4
SOOMRO ET AL
Table 2. Cardiovascular complications in scorpion stings: frequency
distribution among J 79 patients.
No.
I) ECG abnormalities
2) Hypertension
3) Hypotension
4) Echocardiographic abnormalities
5) Pulmonary edemalLVF
6) Cardiopulmonary arrest
129
56
30
25/48
12
4
%
72
31
17
52
7
2
LVF = left ventricular failure.
aminotransferase in 44%, and lactate dehydrogenase
in 25%.
The cardiovascular abnormalities are shown in
Table 2 and include pulmonary edema (7%), transient
hypertension (31 %), and hypotension (17%); the
latter two were adjusted for age. The ECG
abnormalities include sinus tachycardia in 56%, tall
and peaked Twaves in 29%, significant ST depression
or elevation (similar to non-Q infarct pattern) in 17%,
and Tinversion in 15% of cases, occurring singly or in
various combinations (Figure 1). Six patients (3%)
had abnormal Q waves; one each of another 4 patients
had atrial fibrillation, supraventricular tachycardia,
second-degree A V block, and nodal tachycardia. Five
patients had premature ventricular contractions. Most
abnormal ECG changes were corrected in 2 to 14
days, however, abnormalities persisted for up to 6 wk
in one case.
All 12 patients with pulmonary edema, all 3
patients with Q-infarct pattern (without pulmonary
edema), and 10 of 18 patients with non-Q infarct
pattern were studied by echocardiography. For
comparison, 7 of30 cases with only T-wave
anomalies,
15 cases with either normal ECG or with only sinus
tachycardia, and 1 of 3 cases with either nodal or
supraventricular tachyarrhythmias were also studied.
A total of 48 cases were thus studied by
echocardiography within 24 h of sting. Ejection
traction (EF) was normal in 23 (48%) and abnormal in
25 (52%). Systolic dysfunction was mild (EF, 46% to
55%) in 32%, moderate (EF, 31 % to 45%) in 36%,
and severe (EF::::; 30%) in another 32% ofthe 25
cases. In 14 of the 25 patients in whom the initial
echoderived systolic functions were abnormal, serial
echo cardiography was obtained. In this group, the
mean EF had increased trom 36.7 :t 14.6% to 58.4 :t
11.4% (P = 0.000022) with corresponding significant
increases in fractional shortening ([FS], P = 0.00033)
and interventricular septum thickness fraction percent
Journal of the Saudi Heart Association, Vol. 10, No.1, 1998
([IVSTF %], P = 0.0128) (Figures 2 and 3). The
posterior wall thickness traction percent (LVPWTF %)
in this group was not significantly changed, except in a
subgroup of five patients whose posterior wall was
found to be hypokinetic in the initial study but
improved significantly (P < .01) in subsequent studies.
Echocardiography in all 12 patients with
pulmonary edema showed moderate to severe left
ventricular systolic dysfunction. Pulmonary edema
was associated with ECG features ofQ-infarct pattern
in 3 cases, non-Q infarct pattern in 7, and sinus
tachycardia with diffuse T -changes in 2 cases. EF was
severely reduced (22 :t 8%) in three other cases with
Q-infarct pattern. EF was normal in 20%, mildly,
moderately, and severely reduced in 30%, 20%, and
30% of cases, respectively, with non-Q infarct pattern.
Six of? cases with isolated T -wave changes and 14 of
15 cases with normal ECG/sinus tachycardia only had
normal EF. One patient with isolated T-wave changes
had mildly reduced EF, another with sinus tachycardia
had moderately reduced EF (44%), and one patient
with nodal tachycardia also had a moderate reduction
in EF (43.1%).
The recovery time for clinical cardiovascular
function ranged trom 5 to 12 days in all patients. Full
recovery of echo-derived functions was also usually
rapid but lagged behind clinical functional recovery in
a few cases. In one patient, echo-derived functional
recovery took as long as 33 days. Four patients had
cardiopulmonary arrest but were successfully
resuscitated.
Pulmonary Edema
A total of30 patients developed pulmonary edema;
18 of 162 (11.1%) during January 1990 to December
1991 and 12 of968 (1.2%) during January 1992 to
December 1995. The majority ofthese cases (74%)
occurred in patients younger than 15 years. When
compared with the total population of patients with
cardiovascular complications, those with pulmonary
edema had a higher incidence of sweating (80% vs
68%), salivation (60% vs 40%), and priapism (63% vs
33%). Also, leucocytosis (93% vs 68%),
thrombocytosis (50% vs 35%), hyperglycemia (86%
vs 51%), elevated creatinine kinase (80% vs 55%),
and lactic dehydrogenase (66% vs 25%) were more
trequent in patients with pulmonary edema. Twenty of
the 30 patients with pulmonary edema received full
dose of antivenom of at least 5 ampoules. In 1990 and
1991, 10 patients with pulmonary edema had
." 3549771 OaI8;18.o7.9O
"4212428 Cale: 14..07-93
. 4212428 Date: 20-07-93
, 4258029 Date: 27-08.93
'4258029 Date: 06.09.93
Figure 1: Electrocardiographic changes in Scorpion stings.
lA: A 12 lead ECG (14.7.93) of a 16 years old male showing tall T waves, which resolved
later (20.7.93).
I B: 12 lead ECG of a 9 years old male showing ST segment depression in leads 11, 111,
A VF and V I ,V3, V 4 & V 5 and ST elevation with Q waves in leads I & AVL (10.7.90).
A signilicant resolution of these changes is noted on a repeat tracing (18.7.90).
IC: A 12 lead ECG (27.8.93) of an II years old male showing QS pattern and convex ST
segment elevation in leads V2 through V6 with poor R wave progression over these leads
and subsquent resolution of most of these changes (6.9.93).
.3549771 Dat8:18-07-90
ECHO DERIVED EJECTION FRACTION
BEFORE AND AFTER THERAPY
Figure 2. Echocardiographically derived
ejection fraction, within the first 24 h and
following treatment.
8
received 0 to 1 ampoule of antivenom, and 8 had
received 5 to 10 ampoules. However, from 1992, 12
of 12 cases of pulmonary edema had received 10 to
30 ampoules of anti venom. In 1990 and 1991, 12
(7.4%) patients had cardiopulmonary arrest; all
required assisted ventilation and there were three
deaths. All three deaths had received none or 1
ampoule of anti venom. None of the patients who
received five or more ampoules of anti venom died.
In 1992 to 1995, 4 (0.4%) patients had
cardiopulmonary arrest and all four required
ventilation; there were no deaths. There was a
significant drop in the incidence of pulmonary edema
(P < 0.001), cardiopulmonary arrest (P < 0.001), and
death (P < 0.001) following the introduction of the
current early/high-dose serotherapy.
Discussion
The findings in this study show 18.5% of patients
with envenomation had cardiovascular complications
and 10.2% had neurologic complications, supporting
previous
observations
that
cardiovascular
complications were more frequent than neurologic
complications.9 We did not encounter any patients
during the prospective study period with serious
neurologic complications who did not have some
cardiovascular manifestations. The spectrum of
cardiovascular complications that we encountered
included electrocardiographic features simulating
myocardial ischemia and infarction; other
electrocardiographic changes such as sinus
tachycardia, supraventricular arrhythmias, ventricular
ectopics; sinus bradycardia, second-degree AV block,
left ventricular systolic dysfunction, congestive heart
failure, and pulmonary edema. Sinus tachycardia in
56% of cases was by far the most common
cardiovascular
abnormality.
Supraventricular
tachyarrhythmias and various grades of AV block
were rare; they occurred in less than I % of cases
with severe envenomation. Our experience is similar
to previous documentations in the literature.9-16 In
this study, ECG features ofQ-infarct pattern was
associated with 100%, non-Q infarct pattern with
80%, T -wave changes alone with 14%, and sinus
tachycardia/normal ECG with 7% incidence of
cardiovascular dysfunction manifested by pulmonary
edema and/or reduced EF on echocardiography.
Normal ECG, sinus tachycardia, and T -wave
changes generally suggested better ventricular
function.
Journal of the Saudi Heart Association, Vol. 10, No.1
Almost all cardiovascular complications,
including
electrocardiographic
and
echocardiographic changes, were usually reversed
with active management and had little or no residual
abnormalities. This experience is similar to what has
been previously documented.9-16 However, Brand
et aI, in 1988, has documented one case in whom
severe echocardiographic and electrocardiographic
abnormalities had persisted for longer than 4 mo.IO
We encountered one patient in whom echo-derived
systolic dysfunction had persisted for about 1 mo
and another patient whose ECG abnormalities had
persisted for 6 wk. All patients with pulmonary
edema whom we studied by echocardiography
showed moderate to severe left ventricular systolic
dysfunction, thus confirming the cardiac origin of
pulmonary edema in scorpion stings. 17
Hyperstim u lation of the sympathetic and
parasympathetic nervous system has been
documented in animals injected with scorpion
venom, 18-20 and high levels of circulating
catecholamine have been reported in cases of
scorpion
sting.20.22
Sinus
tachycardia,
hypertension, hyperglycemia, and leucocytosis in
our cases can be attributed to the direct effects of
excess circulating catecolamine, whereas priapism,
hypersalivation, sinus bradycardia, various grades of
AV block in these cases were probably due to
excess
levels
of
circulating
parasympathomimetics.23.24
The
electrocardiographic local ization of ischemia or
infarct pattern was rarely limited to the territory of
any particular major coronary artery. Hypokinesia
on echocardiography was also rarely limited to the
territories of the major coronary arteries.
Interventricular septum was most commonly
affected, left ventricular posterior wall was less
common, but global hypokinesia was also noted in
severe cases. Echo-derived indices of systolic
function like EF %, FS %, IVSTF %, and LVPWTF
% were significantly reduced in all the severe cases
but improved with treatment. We did not
demonstrate echocardiographic features of diastolic
dysfunction or increased contractility in any of the
patients studied. Gueron et aI, in 1980, found in
dogs that scorpion venom was arrhythmogenic and
increased left ventricular contractility, systemic
arterial pressure, peripheral resistance, left
ventricular end-diastolic pressure, and pulmonary
arterial pressure.17 Although they found that
cardiac output was reduced significantly in most
experiments, the end-diastolic pressure and
contractility increased. They attributed these
changes to catecholamine-induced decreases in
compliance.
9
CV COMPLICATIONS OF SCORPION STINGS
However, the fmdings in this study that ECG changes ofQ
and non-Q infarct patterns were most frequent in patients
with pulmonary edema and in those with more severe
systolic dysfunction, as shown by echocardiography,
strongly suggest direct myocardial damage.
Histopathologic changes reported in fatal cases of
scorpion stings include degeneration and necrosis of
muscle fibers, interstitial edema, and mononuclear
infiltrates.22.2s-28 These changes bear close similarities to
conditions induced by large doses of catecholamines and
phaeochromocytoma. All ultra-structural changes are
transient and reversible in experimental animals.28 It is
probable that some of the acute cardiac damage
in these cases are due to the effects of excessive amounts
of circulating catecholamine. Small doses of venom
injected into the coronary arteries have been shown to
cause positive inotropic effects, but not ultrastructural
myocardial changes or spasms of a major coronary
artery.28 While smaller doses of venom and smaller
amounts of induced-catecholamine may increase
contractility, it appears clinically that whenever significant
ECG changes and cardiac symptoms occur, significant
direct myocardial damage had already occurred.
The observations on pulmonary edema showed that this
complication was most frequent in children younger than
15 years. These patients manifested the
most severe general symptoms of envenomation and
the most extensive myocardial damage, as detected by
ECG and echocardiography. The current protocol of
administering high-dose antivenom (five or more
ampoules) very early was very effective in protecting
against pulmonary edema (P < 0.001), cardiopulmonary
arrest (P < 0.00 I), and cardiovascular deaths ITom
scorpion envenomation (P < 0.00 I). Thus, scorpion anti
venom not only reduces overall mortality,s.29-JI but it
also seems to prevent the severe toxic effects on the heart.
Since cardiovascular toxicity is the most common serious
complication of scorpion sting, this cardio-protection
probably was critical to the significant reduction in
mortality noted with early or high-dose antivenom.
Conclusions
Cardiovascular complications are the leading causes of
severe morbidity and mortality in scorpion stings. The
major cardiovascular complications
changes in blood pressure, reversible ECG
Journal of the Saudi Heart Association, Vol. 10, No.1, 1998
include
abnormalities simulating myocardial ischemia or
infarction, reversible echocardiographic changes of
systolic dysfunction, and congestive heart failure/
pulmonary
edema.
These
cardiovascular
manifestations appear to have been significantly
decreased and modified by early or high-dose
scorpion anti venom therapy.
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