Edison Reis Lopes
Instituto de Ciências Biológicas e da Saúde,
Universidade de Uberaba, Av. Nenê Sabino 1801, 38055-500
Uberaba, MG, Brasil
Fax: +55-34-318.5279.
Received 9 June 1999
Accepted 9 August 1999
Code Number:OC99192
Key words: Chagas disease - sudden death
In 1922, Chagas and Villela affirmed that they knew of no other
pathology which caused sudden death (SD) in such a high percentage
as Chagas disease (CD). Later studies confirmed this statement and
Bogliolo, a important researcher into the tropical pathology seen
in Brazil this century, affirmed (in a pers. commun. 1978) that in
percentage terms chagasic cardiopathy is responsible for more SD
than ischemic cardiopathy.
The SD in CD, in practically all cases, is cardiac (Rocha 1986)
and as in other cardiopathies (Paulo & Schatz 1971) it is
useful to distinguish between two types: expected (SED) and
unexpected (SUD).
Two important aspects should be highlighted. Firstly, emphasize
that the division between SED and SUD, contributes to the study of
SD in individuals with Chagas disease, facilitating the observation
of risk factors and the identification of those patients needing
preventive care. The second aspect is of a medicolegal nature. For
this branch of medical and legal practice, the unforeseeable aspect
is a fundamental characteristic for diagnosing SD. Consequently the
coroners do not include SED in the sudden deaths.
FREQUENCY, GENERAL CHARACTERISTICS AND IMPORTANCE OF SUDDEN
EXPECTED AND UNEXPECTED DEATHS
Although many studies realized in Brazil and abroad refer to the
high prevalence of SD in CD, few present numerical data, especially
regarding SUD. Studies realized by the author during 1980, in an
endemic area of American trypanosomiasis (Lopes & Chapadeiro
1983) indicated that CD was responsible for 24.1% of the SUD in the
city of Uberaba. A similar study carried out 10 years later (Lopes
et al. 1995) showed that the frequency of this type of SD had
fallen to 6.8%. Data gathered in a field study (Macedo 1973)
suggested that SUD occurs in approximately 37.5% of the chagasic
patients which live in endemic areas. Prata (1959), analyzing
hospitalized patients, observed that SED occurs in approximately
38% of uncompensated chronic chagasic patients. The analysis of
these data combined with others confirms the findings of Dias
(1985) and Prata et al. (1985) who showed that SD (including
unexpected and expected) is the principal cause of death among
those suffering from chronic chagasic cardiopathy.
SUD is the type of death which meets all the classical criteria
of SD (Vibert 1903). In fact it "befalls more or less rapidly, in a
few seconds, hours or even days, but in unpredictable manner,
occurring without any apparent cause, in a hitherto healthy
individual, or at least one who presented only slight disorders, or
at least in appearances to those around him". As this type of SD
occurs in patients without any apparent sign of clinical disease,
it attracts attention and causes fear and constraint.
The majority of chagasics with SUD are male sex and aged on
average 38 years. In 80% of the cases there is an associated family
history.
It should be highlighted that the SUD of a chagasic does not
imply that the patient was asymptomatic. We did a retrospective
investigation (Prata et al. 1986) based on data obtained from
family members and friends together with the circumstances of the
deaths of 35 chagasics who died SED/SUD. This enabled us to verify
that 35.2%, while still alive, did not present any symptoms or
suspicion of cardiopathy. This group comprises those chagasic
patients which present SD as the first manifestation of the
disease. In 57.1% of the cases, we managed to detect a history of
dizziness (42.8%), dyspnoea during physical activity (48%), loss of
consciousness (34.2%) and palpitations (31.4%). Dysphagia and
constipation were present in 38% of the cases. The death having
been brought on by physical effort, emotion and rarely during
sleep. In half of the cases, the lethal event was instantaneous and
in the remainder it was preceded by premonitory symptoms. Regarding
the electrocardiograms realized between one to five years before
death, 95% of these cases showed abnormalities.
SD in indetermined forms of CD (Rassi & Rassi 1998) seem to
be an exception. Rare cases have been reported of SUD in chagasic
patients with a normal electrocardiogram before death (Porto 1974,
Manzullo & Darraidou 1983, Bestetti et al. 1993). However, in
all, there are elements lacking for these to be characterized as an
indetermined form. In addition, the patients of Porto and Manzullo
et al., were not autopsied, which means it is impossible to
definitively attribute responsibility for the SD to CD.
From an anatomopathological point of view, in the cases of SUD,
the hearts present essentially the same picture as those chagasic
patients which die from SED or from nonsudden death. The
differences are manifested especially in the shape, volume and
weight of the organ and the aspect of the cavities and behavior of
the lymph nodes situated between the aorta and the pulmonary
(subepicardial lymph nodes). The shape is slightly elongated and
the weight and volume show a slight increase [Heart weights ranged
from 180 to 560 g (average 390 g) in chagasics with SD. In
chagasics who died in cardiac failure the heart weights ranged from
180 to 1030 g (average 544 g) and in asymptomatic chagasics who had
a violent death, the heart weights range from 240 to 450 g (average
310 g)]. The enlargement of subepicardial lymph nodes is more
frequent and severe in chagasic patients with SUD than those which
present other types of death. These macroscopic characteristics are
of extreme importance and should be borne in mind by coroners and
by forensic pathologists. Microscopically, the fundamental lesion
is inflammatory and simultaneously compromises the epicardium,
myocardium and parietal endocardium. From a qualitative point of
view, the inflammatory process has similar characteristics to those
observed in chagasic patients with cardiac insufficiency;
quantitatively, however, the alterations are more suttle in the
chagasics with SUD than those which present SED or nonsudden death.
The SUD of a chagasic individual is of great interest for the
coroner as it is a suspicious type of death, in that its
circumstances arouse doubts as to whether the cause was natural or
violent. It frequently leads to problems with the police, labor law
and others.
An electrophysiologic study in chronic chagasic patients
(Scanavacca et al. 1994) included, among chagasic patients which
might present with SED two distinct population: (1) chagasics with
recurrent sustained tachycardia and which present SD in the
evolution; (2) chagasics with congestive cardiac insufficiency who
present SD as the sinal event. There is yet a third population:
chagasics with SD as the first manifestation of the cardiopathy. In
that last cases the SD is inexpected. According with Scanavacca et
al., chagasic patients may benefit of electrophysiologic study
after a critical clinical evaluation.
THE MECHANISM OF SUDDEN DEATH IN PATIENTS WITH CHAGAS'
DISEASE
One of the most striking characteristics of both SUD and SED in
CD is that the death occurs immediately, only a few minutes after
onset of the symptoms.
As already mentioned in the beginning of this paper, SD in
chagasics is classified, in almost all cases, as cardiac SD, with
non-cardiac causes being an exception, such as for example
encephalic vascular accident (Lopes et al. 1990). From the
observations to date, it is known that it is almost always preceded
by fibrillation which constitutes the terminal arrhythmia.
Among the factors which interact to cause the ventricular
fibrillation, we highlight the anatomic substrate, the trigger
elements and the facilitating factors. Foci of inflammation, areas
of fibrose, ventricular dilation and vortex lesion favor the
occurrence of reentry, which constitutes the principal
electrophysiological mechanism involved in the chain of events
leading to ventricular tachyarrhythmias in chronic chagasic
cardiopathy. However, the presence of anatomic substrate alone is
not capable of originating the tachyarrhythmia. The participation
of trigger elements, in this case represented by the ventricular
extrasystoles, is also usually necessary. Thus the propagation of
these premature impulses through zones of unidirectional block and
conduction disturbances, resulting from the myocardial structural
alterations are capable of causing the reentry process. Completing
the model of arrhythmic SD, is the role of the facilitating
factors, which on interacting with the substrate and trigger
elements may cause electrical instability in the system and cause
fatal arrhythmias, such as ventricular fibrillation. The acute
hemodynamic deterioration, hypoxemia, acidosis, electrolytic
disorders, lesions of the autonomous nervous system (intra and
extracardiac) constitute examples of factors which can destabilize
the arrhythmogenic substrate. Amongst these, the behavior of the
autonomous nervous system merits special attention.
CARLOS CHAGAS AND SUDDEN DEATH IN PATIENTS WITH CHAGAS
DISEASE
As occurred with nearly all aspects of the CD, the discoverer of
trypanosomiasis cruzi had his attention drawn to the SD of the
endemia.
In 1912, during a conference held in São Paulo, Chagas
manifested himself thus: "In the regions where thanks to the
disease the number of adult individuals with profound cardiac
disorders is impressive, one being almost able to affirm that the
totality of the inhabitants of houses infested by the barbeiros
present morbid phenomena with regard to the central circulation
organ. An immediate consequence of this fact is the great number of
rapid deaths occasioned by the disease, it being really impressive,
in the statistics of lethality, the number of people who suddenly
die from cardiac syncope". Here, it seems to us that Carlos Chagas
was making reference to those cases we now consider as SED.
In 1916, Chagas made observations regarding cases of SUD. In a
paper published in the Memórias do Instituto Oswaldo
Cruz, he related: "Of great frequency are also the sudden
deaths in the cardiac forms of the disease. This very fact
constitutes one of the most curious notes in the clinical history
of this trypanosomiasis, the lethality of which and number of
deaths is really surprising. It being rare for families living in
infested zones not to report the loss of one or more of its members
in this way. Sometimes they die while still young, in full activity
and with an apparently satisfactory state of health.
We have heard from sources worthy of trust, manifested surprise
by the frequency of these SD, verified in middle-aged individuals,
in full working conditions; and in our hospital service, we possess
observations of some patients whose demise was from an almost
instantaneous death. These, moreover, presented accentuated cardiac
syndrome".
By 1916, Chagas had already published considerations regarding
the mechanism of SD in CD: "What is the immediate cause of the
sudden death? Is it the acute dilatation of the right ventricle by
exhaustion of the tone of the heart muscle or stopping of the organ
in diastole by the loss of that function? Is it a syncope of reflex
nature dependent upon the conditions of the myocardium, or rupture
of the muscle, as in one observation we made"?. In this same
article cited one of the rare mechanisms of SED in CD: rupture of
the right ventricle. To date, only two other cases of this
pathology have been reported (Tostes Jr et al. 1990).
Finally, in 1922, Chagas and Villela published the article
"Cardiac form of American trypanosomiasis" at broach the SD in CD
they refer: "sudden death is extremely frequent in the region of
endemic trypanosomiasis". (...) "We must at once refer to Mac
William's hypothesis which was formed the basis for our argument
and in which SD in intensive disorders of rhythm would be
explicable by fibrilation of the ventricle".
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