Download chapter 5 sudden and unexpected death

Sudden and Unexpected
Death from Natural Causes
Section 1 General consideration
1. Definition of sudden unexpected death
The definition of sudden unexpected death is
referred to as a sudden death of an individual who
appears healthy and dies suddenly within a few minutes
or several hours due to pre-existing disease or functional
disorder.
The official definition of a sudden unexpected death
as described by WHO is that an individual dies from
natural diseases within 24 hours since symptoms appear.
Three characteristics in the cases of sudden and
unexpected death:
(a) The suddenness of the death;
(b) The unexpectedness of the death;
(c) Natural diseases or functional disorders as the causes
of death.
The violent deaths, although occurring suddenly in
most cases as they do, are not within the scope of sudden
unexpected death.
2. Causes of sudden unexpected death
Diseases of any human physical system may lead to
sudden unexpected death.
Leading causes: diseases of cardiovascular system, the
diseases of central nervous system and respiratory system
rank second. The diseases of gastrointestinal and
genitourinary system are less commonly to cause the
sudden unexpected death.
Diseases of respiratory system are most commonly
seen to lead to sudden death in neonate and children.
Diseases of cardiovascular system account for the
major cause in the sudden unexpected deaths in adults.
Certain external factors such as emotional distress
and physical exertion may predispose the onset of the
disease that leads to the sudden death.
3. The purposes for medico-legal investigation
in sudden unexpected death
Medico-legal autopsy must be conducted under the
following conditions:
1. In cases suspected to be violent death.
2. In cases of violent deaths that have been disguised to
be sudden unexpected death from natural causes.
By medico-legal investigation, some occupational or
grave infectious diseases may be detected. Proper
prophylactic measurements may be taken.
Section 2 The common causes of sudden
and unexpected death
1. Cardiovascular system
Most sudden and unexpected deaths are caused by
lesions in the cardiovascular system.
(1) Coronary artery disease
i. Coronary insufficiency
Coronary insufficiency from narrowing of the lumen
of major vessels may lead to chronic ischemia and hypoxia
of the muscle distal to the stenosis.
If the ischemia region involves the pace-maker node
or a major branch of the conducting system, the liability
to rhythm abnormalities is increased.
ii. Complications of atheroma
Ulcerative atheromatous plaques may rupture, filling
the vessel partially or completely with cholesterol, fat and
fibrous debris.
The endothelial cap of a ruptured plague may act as a
valve within the vessel and cause a complete obstruction.
Sub-intimal hemorrhage, where bleeding occurs into a
plague, expanding it suddenly and often reducing or
blocking the lumen.
Coronary atheroma
Coronary atheroma
iii. Coronary thrombosis
Less than one-third of sudden cardiac deaths has
been detected to have a coronary thrombus at autopsy as
pure stenosis and complications of atheroma are much
more common.
Thrombi are still frequent and are often associated
with a myocardial infarct.
Multiple thrombi also occur, some being postinfarction, due to a stagnant circulation.
iv. Myocardial infarction
Myocardial infarction occurs when a severe or a
complete occlusion occurs in a coronary artery, and if the
collateral circulation is not sufficient to maintain the
muscle.
If 70% or more of the lumen of a major branch is
blocked, an infarct commonly develops.
The effect of a large infarct is either to reduce cardiac
function because of pump failure, as the necrotized muscle
cannot contract, or it leads to arrhythmias and ventricular
fibrillation.
The fatal effects of an infarct may appear at any time
after the muscle has become ischemic though many hours
are needed for an infarct to become visible.
Figure 17.1 The paler area at the lower Figure 17.2 Haemopericardium due to a
edge is a regional myocardial infarction of ruptured anterior myocardial infarct. Death was
several days' duration.
due to cardiac tamponade.
Myocardial infarction
Myocardial infarction
Myocardial infarction
v. Rupture of myocardial infarct
A ruptured myocardial infarct may cause sudden
death from a hemopericardium and cardiac tamponade.
Most commonly found in old person, who have a soft,
senile myocardium, but can occur in anyone.
Tends to take place two or three days after the onset
of the infarction when the necrotic muscle is becoming
soft.
Mural thrombus may develop over the inner surface
of a myocardial infarct. Parts of it may break off, leading
to emboli in the systemic circulation, which may cause
infarcts in kidney, spleen and brain.
Rupture of myocardial infarct
vi. Myocardial fibrosis
Another complication of myocardial infarction is the
myocardial fibrosis which may develop when a myocardial
infarct heals.
Large plaques on the endocardium, or in the wall of
the ventricle or septum may later interfere with cardiac
function or with the conducting system.
A large fibrotic area on the free wall of the left
ventricle may later swell due to the high pressure during
systole, forming a cardiac aneurysm. These aneurysms
rarely rupture, as they are tough and fibrotic.
vii. Papillary muscle rupture
This can occur due to infarction and necrosis, and
allow part of the mitral valve to prolapse, with signs of
valve insufficiency and perhaps sudden death.
(2) Hypertensive heart disease
This condition may lead to sudden cardiac death from
left ventricular hypertrophy.
In hypertension, the heart may increase to 600 g or more
and the muscle mass thus outgrows it coronary supply, even
if the coronary arteries are healthy.
Atheroma is often associated with hypertension, so that
the enlarged muscle mass is further deprived of even a
normal flow and becomes ischemic. Such muscle is unstable
and irritable and easily jumps into arrhythmias and
fibrillation, which causes the sudden death of an individual.
(3) Primary myocardial disease
This is much less common than the ischemic condition of
the heart. It may include several kinds of myocardial
lesions.
Myocarditis that occurs in many infective diseases, such
as diphtheria and virus infections including influenza,
disseminated sarcoidosis ( myocardial sarcoidosis).
In sudden death pathology, a myocarditis of unknown
aetiology is sometimes discovered on histology of autopsy
tissues, known as isolated, Fiedler’s or Saphir’s
myocarditis.
Myodarditis
Myodarditis
Cardiomyopathy, where a large heart shows certain
abnormal histological characteristics, including：
HCM (hypertrophic cardiomyopathy), : huge hearts of
over 1000 g; asymmetric massive thickening of ventricular
walls.
CCM (congestive cardiomyopathy) : dilatation of the
chambers with thinning of the ventricular walls.
RCM (restrictive cardiomyopathy ): evident fibrotic
thickening of the endomyo-cardium.
ARVD/C (arrhythmogenic right ventricular
cardiomyopathy(dysplasia)) : displacement of myocardial
fibers by fatty tissue and collagen fibers.
2. Central nervous system
(1) Ruptured berry aneurysm
Subarachnoid hemorrhage: a relatively common cause of
sudden collapse and often rapid death in young to middleaged people, due to a ruptured aneurysm of a basal cerebral
artery.
Berry aneurysms develop at a weak spot in the vessel
wall, which may be of any size from a millimeters to several
centimeters in diameter and may be single or multiple. The
apex can rupture, especially at any sudden rise in blood
pressure, such as from exercise or emotion.
Ruptured berry aneurysm
(2) Cerebral hemorrhage
Sudden bleeding into the brain substance is common,
usually in old age and in those with significant hypertension.
The hemorrhage most often takes place in the external
capsule of one hemisphere from rupture of a lenticulo-striate
artery. The sudden expansion of a hematoma compresses the
internal capsule and may destroy some of it, leading to a
hemiparesis.
Other places where bleeding occurs include the
cerebellum and mid-brain. Some bleedings in the brain-stem
may lead to marked hyperpyrexia.
Figure 17.5 A large intracerebral haemorrhage in the
internal capsule, with extension into the ventricle.
Figure 17.6 Pontine haemorrhage in a hypertensive individual.
Subarachnoid hemorrhage and cerebral hemorrhage
cerebral hemorrhage
pone hemorrhage
(3) Cerebral thrombosis and infarction
This is rarely a cause of sudden or unexpected death,
as the process is relatively slow, though neurological
symptoms and signs consequent on infarction of a
substantial part of the brain may be severe.
3. Respiratory system
The major cause of sudden death within the respiratory
organ is again vascular.
Pulmonary embolism
In almost every case, the source of the emboli is in the
leg veins and pelvic veins. After any tissue trauma, or even
surgical operation, especially where immobility or bed rest
occurs, deep vein thrombosis develops.
Other rare causes of sudden death in the respiratory
system include a massive hemoptysis from cavitating
pulmonary tuberculosis or from a malignant tumor, though
the latter is a rare complication.
pulmonary tuberculosis
pulmonary tuberculosis
pulmonary pneumonia
pulmonary pneumonia
pneumothorax
4. Gastrointestinal system
Once again, causes of death in this system may be
vascular, in that very severe bleeding from a gastric or
duodenal peptic ulcer can be fatal in a short time, but most
are moderate enough to allow medical or surgical treatment.
Perforation of a peptic ulcer can be fatal in hours if not
treated and intestinal gangrene due to strangulated hernias
and torsion due to peritoneal adhesions can also be
fulminating and fatal conditions.
Nodal hepatocirrhosis
Gastric hemorrhage
Acute necrotic pancreatitis
Acute necrotic pancreatitis
Gastric perforation
Bacteria diarrhea
5. Genitourinary system
If a woman in child-bearing age is found unexpectedly
death, a complication of pregnancy must be considered.
Abortion is one possibility, especially in countries where
illegal abortion is still very common. In these cases death from
vagal shock, hemorrhage and infection from septic
instrumentation and possibly air embolism must be considered.
A ruptured ectopic gestation, usually tubal in position, is
another grave emergency that can be fatal due to
intraperitoneal bleeding, unless rapidly treated by surgical
intervention.
ectopic gestation
ectopic gestation
ectopic gestation
amniotic fluid embolism
amniotic fluid embolism
amniotic fluid embolism
amniotic fluid embolism
amniotic fluid embolism