Chapter 6 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. 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. 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. 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 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. 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. 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. 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. 2. Causes of sudden unexpected death Diseases of any human physical system may lead to 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. 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 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. 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. Certain external factors such as emotional distress and physical exertion may predispose the onset of the disease that leads to the sudden death. Diseases of respiratory system are most commonly seen to lead to sudden death in neonate and children. 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. 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. 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. 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. 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. By medico-legal investigation, some occupational or grave infectious diseases may be detected. Proper prophylactic measurements may be taken. 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. 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. 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. 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. Most sudden and unexpected deaths are caused by lesions in the cardiovascular system. (1) Coronary artery disease (1) Coronary artery disease i. Coronary insufficiency 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. 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. If the ischemia region involves the pace-maker node or a major branch of the conducting system, the liability to rhythm abnormalities is increased. 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. Most sudden and unexpected deaths are caused by lesions in the cardiovascular system. (1) Coronary artery disease (1) Coronary artery disease i. Coronary insufficiency 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. 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. 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. 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. 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. ii. Complications of atheroma Ulcerative atheromatous plaques may rupture, filling the vessel partially or completely with cholesterol, fat and fibrous debris. 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. 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

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. 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. Thrombi are still frequent and are often associated with a myocardial infarct. Multiple thrombi also occur, some being post- infarction, due to a stagnant circulation. Multiple thrombi also occur, some being post- infarction, due to a stagnant circulation. 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. 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. Thrombi are still frequent and are often associated with a myocardial infarct. Multiple thrombi also occur, some being post- infarction, due to a stagnant circulation. Multiple thrombi also occur, some being post- infarction, due to a stagnant circulation.

iv. Myocardial infarction 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. 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. 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 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. 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. iv. Myocardial infarction 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. 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. 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 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. 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.

Myocardial infarction

v. Rupture of myocardial infarct v. Rupture of myocardial infarct A ruptured myocardial infarct may cause sudden death from a hemopericardium and cardiac tamponade. 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. 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. 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. 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. v. Rupture of myocardial infarct v. Rupture of myocardial infarct A ruptured myocardial infarct may cause sudden death from a hemopericardium and cardiac tamponade. 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. 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. 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. 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 vi. Myocardial fibrosis Another complication of myocardial infarction is the myocardial fibrosis which may develop when a myocardial infarct heals. 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. 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. 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. vi. Myocardial fibrosis vi. Myocardial fibrosis Another complication of myocardial infarction is the myocardial fibrosis which may develop when a myocardial infarct heals. 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. 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. 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 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. 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. vii. Papillary muscle rupture 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. 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 (2) Hypertensive heart disease This condition may lead to sudden cardiac death from left ventricular hypertrophy. 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. 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. 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. (2) Hypertensive heart disease (2) Hypertensive heart disease This condition may lead to sudden cardiac death from left ventricular hypertrophy. 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. 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. 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 (3) Primary myocardial disease This is much less common than the ischemic condition of the heart. It may include several kinds of myocardial lesions. 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). 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. 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.

Cardiomyopathy, where a large heart shows certain abnormal histological characteristics, including hypertrophic cardiomyopathy(HCM), congestive cardiomyopathy (CCM) and restrictive cardiomyopathy (RCM) as well as recently defined arrhythmogenic right ventricular cardiomyopathy(dysplasia) (ARVD/C). Cardiomyopathy, where a large heart shows certain abnormal histological characteristics, including hypertrophic cardiomyopathy(HCM), congestive cardiomyopathy (CCM) and restrictive cardiomyopathy (RCM) as well as recently defined arrhythmogenic right ventricular cardiomyopathy(dysplasia) (ARVD/C). HCM: huge hearts of over 1000 g; asymmetric massive thickening of ventricular walls. HCM: huge hearts of over 1000 g; asymmetric massive thickening of ventricular walls. CCM: dilatation of the chambers with thinning of the ventricular walls. CCM: dilatation of the chambers with thinning of the ventricular walls. RCM: evident fibrotic thickening of the endomyo- cardium. RCM: evident fibrotic thickening of the endomyo- cardium. ARVD/C: displacement of myocardial fibers by fatty tissue and collagen fibers. ARVD/C: displacement of myocardial fibers by fatty tissue and collagen fibers.

MyodarditisMyodarditis

MyodarditisMyodarditis

2. Central nervous system (1) Ruptured berry aneurysm Subarachnoid hemorrhage: a relatively common cause of sudden collapse and often rapid death in young to middle- aged people, due to a ruptured aneurysm of a basal cerebral artery. Subarachnoid hemorrhage: a relatively common cause of sudden collapse and often rapid death in young to middle- aged 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. 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. 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. Other places where bleeding occurs include the cerebellum and mid-brain. Some bleedings in the brain-stem may lead to marked hyperpyrexia.

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. 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 3. Respiratory system The major cause of sudden death within the respiratory organ is again vascular. 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. 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. 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 pneumonia

pneumothoraxpneumothorax

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. 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. 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

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. 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. 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. 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

amniotic fluid embolism