Sudden Unexpected Death: Causes and Contributing Factors

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In the world of medical examiners, coroners, and pathologist involved in forensic autopsies, "sudden death" does not mean instantaneous death. This outline is an outgrowth of the category referred to as SIDS (sudden infant death syndrome). I suppose one could say "in less than 24 hours". But the implication is of a rapid and unexpected death...mostly unwitnessed...and without obvious cause when the body was found.

  1. PRIMARILY CARDIAC-ABNORMALITY DEATHS: Keep in mind that trauma or metabolic vacillations of acute and chronic illness superimposed on significant cardiac lesions can trigger acute or chronic electrical or mechanical decompensation and death.

    1. Epicardial Coronary Artery Abnormalities:
      1. Coronary Atherosclerosis:
        1. Chronic...segmental or pipestem stenosis.
        2. Acute myocardial infarction, atherogenic.
        3. Chronic atherosclerosis with chronic changes in myocardial parenchyma.
        4. Constriction of artery ostia.
      2. Congenital abnormalities of coronary arteries:
        1. Anomalous origin from pulmonary artery.
        2. Other type of coronary AV fistula.
        3. Origin of left coronary artery from right sinus of Valsalva.
        4. Origin of right coronary artery from left sinus of Valsalva.
        5. Hypoplastic or aplastic coronary arteries.
        6. Transmyocardial coronary-intracardiac shunt.
      3. Other coronary problems:
        1. obstucting/stenosing ostial mural folds ("flutter valve-like"), calcific spurs or constrictions, or partial or circumferential intimal webs (FA-06-90).
        2. aneurysm with rupture (FA07-33).
      4. Coronary artery embolism or thrombosis from:
        1. Thrombosis over an artery lesion.
        2. Aortic or mitral endocarditis.
        3. Prosthetic aortic or mitral valves.
        4. Abnormal native valves or left-sided mural thrombus.
        5. Platelet-aggregate embolism.
      5. Coronary arteritis:
        1. Polyarteritis nodosa, progressive systemic sclerosis, giant cell arteritis.
        2. Mucocutaneous lymph node syndrome (Kawasaki's disease) with arteritis, then aneurysms.
        3. Syphilitic coronary ostial stenosis.
        4. Focal/segmented arteritis, NOS (A80-547, FA84-115).
      6. Miscellaneous mechanical obstruction of coronary arteries:
        1. Ulceration of an atherosclerotic plaque.
        2. Coronary artery dissection in Marfan's syndrome.
        3. Coronary artery dissection in pregnancy.
        4. Prolapse of aortic valve myxomatous polyps into coronary ostia.
        5. Dissection or rupture of sinus of Valsalva.
        6. Coronary vasospasm: especially if on cocaine; even transmural infarcts without apparent coronary lesions (Am.J.H. 88:219, 1974).
        7. Occult trauma to a normal-appearing coronary artery.
        8. Mural thickening due to metabolic deposits or intimal proliferation (JAMA 231:952, 1975):
          bulletMucopolysaccharidoses.
          bulletHomocystinuria.
          bulletFabray's Disease.
          bulletAmyloidosis.
          bulletJuvenile intimal sclerosis (idiopathic arterial calcification of infancy).
          bulletIntimal hyperplasia associated with contraceptive steroids or with postpartum state.
          bulletPseudoxanthoma elasticum.
          bulletCoronary fibrosis associated with radiation therapy.
    2. Endomyocardial coronary artery perforating branches:
      1. arteriolitis.
      2. mural thickening arteriolopathies.
      3. emboli. 
    3. Hypertrophy of Ventricular Myocardium:
      1. Left ventricular hypertrophy associated with chronic stenosing coronary atherosclerosis.
      2. Hypertensive heart disease without significant coronary atherosclerosis (be especially careful to view heart weight in view of the body weight).
      3. cardiomyopathy of morbid obesity: (relative cardiomegally [heart to total body wt. ratio normal], LV dilation, and myocyte hypertrophy in absence of interstitial fibrosis); 50% die of sudden cardiac death.
      4. Hypertrophic myocardium secondary to valvular heart disease.
      5. Hypertrophic cardiomyopathy: by late 2001, some 10 genes have been noted in association with HCM...afflicting 1/500 adults.
        1. Obstructive
        2. Non-obstructive (A83-717)
      6. Primary or secondary pulmonary hypertension (remember, they can be found dead before there is that much increase in RV thickness; so need lots of lung sections to rule this out):
        1. Advanced chronic right ventricular overload.
        2. Pulmonary hypertension in pregnancy.
    4. Myocardial Diseases and Heart Failure:
      1. Chronic congestive heart failure:
        1. Ischemic cardiomyopathy.
        2. Idiopathic cardiomyopathy (A90-893, FA91-640).
        3. Alcoholic/toxic cardiomyopathy.
        4. Hypertensive cardiomyopathy.
        5. Post-myocarditis cardiomyopathy (FA91-640).
        6. Postpartum cardiomyopathy.
        7. Familial cardiomyopathy.
        8. Hyper-endocrine cardiomyopathy.
        9. Hypo-nutritional cardiomyopathy.
        10. Chronic CHF, NOS: and don't overlook additional causes of high-output failure such as occult shunts (Pagett’s disease of bone can do it., e.g.).
      2. Dilated cardiomyopathy: Do to practically any of the above or below influences on the heart muscle, the heart enlarges, then the chambers dilate (etiologies: idiopathic, inflammatory, metabolic,genetic, toxic, peripartum, infiltrative, hypersensitivity, arrhythmogenic, and rheumatologic).
      3. Acute cardiac failure:
        1. Massive acute myocardial infarction.
        2. Acute or chronic myocarditis (A-02-1, FA-06-127).
        3. Acute alcoholic cardiac dysfunction.
        4. Ball-valve malfunction in aortic stenosis prosthesis.
        5. Mechanical disruptions of cardiac structures:
          bulletRupture of ventricular free wall.
          bulletDisruption of valvular apparatus:
          bulletPapillary muscle.
          bulletChordae tendineae.
          bulletLeaflet.
        6. Acute pulmonary edema in noncompliant ventricles.
        7. Myocardial bridging - is supposedly fairly common at autopsy, being mostly in the left coronary, the first 10 to 20 mm. Deaths ascribed mostly when also involves the posterior circulation (average death is a 31 year old, with or without associated physical activity or excitement) or associated with some other lesion in the (anterior versus posterior) opposite coronary system. The thicker the bridge, the more likely its significance.
        8. Infarction associated primarily with oxygen “supply-demand” disproportion (JAMA 231:952, 1975):
          bulletAortic stenosis, all forms.
          bulletIncomplete differentiation of the aortic valve.
          bulletAortic insufficiency.
          bulletCarbon monoxide poisoning.
          bulletViral toxicosis.
          bulletProlonged hypotension.
        9. Miscellaneous odd infarctions (JAMA 231:952, 1975):
          bulletMyocardial contusion.
          bulletThrombocytosis/leukemic leukostasis.
          bulletAMI with normal coronaries.
    5. Inflammatory, Infiltrative Neoplastic, and Degenerative Processes:
      1. Acute viral myocarditis with or without ventricular mechanical dysfunction.
      2. Myocarditis associated with the vasculitides.
      3. Sarcoidosis.
      4. Progressive systemic sclerosis.
      5. Amyloidosis (A78-350).
      6. Hemochromatosis (FA91-607).
      7. Idiopathic giant cell myocarditis.
      8. Senile myocardium: usually a small heart & myocardium soft (elderly person found dead of "old age")
      9. Chagas’ disease.
      10. Arrhythmogenic right ventricular (fatty) dysplasia (ARVD) [as opposed to more ordinary fatty infiltration]; ARVD tends to be fatty change out of all proportion to the body weight and involving even into the interior...focally transmural...myocardium] (A79-451, FA-94-57, FA-95-9, FA-95-36, A-01-2, FA-01-72). 85% of diagnoses of ARVD are at sudden unexpected adult death.
      11. Neuromuscular diseases (e.g., muscular dystrophy, Friedreich's ataxia, myotonic dystrophy) (FA-94-113).
      12. Intramural tumors:
        1. Primary benign or malignant.
        2. Metastatic.
      13. Obstructive intracavitary tumors:
        1. Neoplastic - benign or malignant.
        2. Thrombotic - enlarging chronic thrombus.
        3. Chronic lymphocytic myocarditis: this can be very subtle and may require numerous cardiac sections in order to locate at least several microscopic foci of lymphocytic infiltrates (FA86-261, FA91-605, FA91-631, FA92-23).
        4. Myxoid heart syndrome: mucosubstances in conduction system, valves, etc. (See I,5,c.); a forme frust Marfan's [Nat'l Marfans Foundation]
        5. Intramural arteritis, NOS (A82-655) or other arterial occlusions.
        6. Hurler's (and other similar storage disease) syndrome (gargoylism): accumulation of mucopolysaccharide in RES cells.
        7. Fabry's disease: foamy accumulation in smooth muscle, endothelial and perithelial cells.
        8. Pompe's disease: excessive glycogen storage in heart muscle.
        9. Look for signs of other storage disorders.
    6. Diseases of the Cardiac Valves:
      1. Valvular aortic stenosis/insufficiency.
      2. Mitral valve disruption, see above.
      3. Prolapse of myxoid, floppy mitral valve having accumulation of acid mucosubstances.
      4. Endocarditis.
      5. Prosthetic valve dysfunction.
    7. Congenital Heart Disease:
      1. Congenital aortic or pulmonic valve stenosis.
      2. Right-to-left shunts with Eisenmenger’s physiology:
        1. Advanced disease.
        2. During labor and delivery.
      3. After surgical repair of congenital lesions; e.g., tetralogy of Fallot.
      4. CHARGE Syndrome (the Foundation) [note the coloboma...abnormal eye pupil shape...plus various cardiac defects]
    8. Electrophysiologic Abnormalities:
      1. Abnormalities of the electrical conducting system:
        1. Fibrosis of the His-Purkinje system:
          bulletPrimary degeneration (Lenegre's disease).
          bulletSecondary to extension of fibrosis and calcification from the mitral valve ring/"cardiac skeleton" (Lev's disease).
          bulletPost-viral conducting system fibrosis.
          bulletHereditary conducting system disease.
      2. Prolonged Q-T interval syndromes [2/3's have history of fainting/syncope] (SADS Foundation):
        1. Congenital idiopathic:
          bulletWith deafness.
          bulletWithout deafness.
        2. Congenital/deaf: Jervell-Lange-Nielson syndrome.
        3. Romano-Ward syndrome: sudden childhood deaths or death at any age on induction of anesthesia.
        4. Acquired:
          bulletDrug effect.
          bulletElectrolyte abnormality.
          bulletToxic substances.
          bulletHypothermia.
          bulletCNS injury.
          bulletIdiopathic.
        5. Idiopathic ventricular fibrillation (does not cause heavy lungs if happens abruptly and not super-imposed on another CHF event):
          bulletAbsence of identifiable structural or functional causes, even with extensive sampling of conduction system
          bulletSleep-death in refugees of Southeast Asia, Japan, Philippines:
          bulletBangungut.
          bulletPokkuri.
          bulletNonlaitai.
    9. Electrical Instability Related to Neurohumoral and Central Nervous System Influences:
      1. Catecholamine-dependent lethal arrhythmias.
      2. Central nervous system related:
        1. Psychic stress, emotional extremes:
          bulletpsychiatric deaths:
          bulletBell's psychosis..."acute exhaustive mania".
          bulletNeuroleptic malignant syndrome.
          bulletPhenothiazine-related arrhythmias.
        2. Auditory/sight related...scared to death by noise/startling surprise.
        3. "Voodoo" death in primitive cultures.
        4. Diseases of the cardiac nerves.
        5. Congenital Q-T interval prolongation.


  2. SUDDEN INFANT DEATH SYNDROME (SIDS) AND SUDDEN DEATH IN CHILDREN:

    1. Sudden infant death syndrome:
      1. Immature respiratory control functions.
      2. Susceptibility to lethal arrhythmias for uncertain reasons.
      3. Congenital heart disease.
      4. Myocarditis.
      5. Fatty liver, metabolic disorder.
    2. Sudden death in infants/children:
      1. Eisenmenger syndrome: aortic stenosis, hypertrophic cardiomyopathy, pulmonary atresia.
      2. Uhl's anomaly : focal or complete severe thinning of right ventricular non-septal myocardium.
      3. After corrective surgery for congenital heart disease.
      4. Myocarditis.
      5. histiocytoid cardiomyopathy: genetic aberration causes presence of enlarged foamy cells & granular (excess mitochondria) cardiocytes (cardiac myocytes) & tends to be female infants.
      6. Septicemia [FA-85-157]
      7. "Overlying"/bed-clothing suffocation: (1) prone sleeping...blanched postmortem skin around mouth & nose while lividity is elsewhere in the prone position hints at a type of auto-suffocation as the baby's head bobs and lands face down in thick soft covers or pillow; BUT, it does not rule out a cleverly set up homicide. By the same token, prone lividity with blanched contact spot on cheek or side of face does not rule out bobbing auto-suffocation with a terminal, agonal seizure that turns the head to the side. (2) a parent or other large person who is impaired or maybe a fitful but very deep sleeper can miss and "overly" an infant and suffocate it.
      8. Reye's syndrome: liver may not be grossly yellow.
      9. Occult carbon monoxide poisoning: consider circumstances and note the bright red postmortem blood, being also relatively bright red even after formalin fixation.
      10. Homicidal/accidental: suffocation; chest wall compression; shaken infant; neglect...dehydration; hypothermia/hyperthermia.


  3. SUDDEN DEATH in PREGNANCY/POSTPARTUM: any of those already noted; and...
    1. toxemia (usually before/beginning of labor)
    2. acute cardiomyopathy (usually postpartum)
    3. ruptured Berry aneurysm (during labor)
    4. amniotic fluid embolism (during labor)
    5. acute fatty liver of pregnancy
    6. HELLP syndrome
    7. pulmonary embolism (postpartum)
    8. septicemia
    9. hemoglobinopathy, especially SS & SC.
    10. thrombophilia with PE or arterial thrombosis (cardiac or CNS).

  4. MISCELLANEOUS:

    1. Sudden death during extreme physical activity (such as in military recruits [JAMA 256:2696, 1986]; sometimes the exertion is not extreme [JAMA 225:1319, 1973]; intense football practice in those with sickle-cell trait (Mike Bianchi, The Orlando Sentinel, & in The State newspaper 7/20/08 page C12); otherwise healthy persons being acutely restrained and struggling...acute metabolic acidosis.
    2. Agitated delirium (violently combative, out-of-control reaction): often in a setting of drug use such as cocaine, amphetamines, etc. (invariably febrile...40.2 degrees C. average...and 2/3rds die @ scene or during transport; if to hospital, complicated by rhabdomyolysis, DIC, renal failure).
    3. Mechanical interferences with venous return:
      1. Acute cardiac tamponade.
      2. Massive pulmonary embolism: obese lady with necrotic, infected submucosal uterine "fibroid" [FA-07-3].
      3. Acute intra-cardiac thrombosis.
    4. Dissecting aneurysm of the aorta.
    5. Toxic/metabolic disturbances:
      1. Electrolyte disturbances.
      2. Metabolic disturbances.
      3. Proarrhythmic effects of anti-arrhythmic drugs.
      4. Proarrhythmic effects of noncardiac drugs.
      5. Be on the lookout for acetaminophen-induced central lobular hepatic necrosis.
      6. Diabetic: the first "diabetic attack" can be the last (postmortem urinalysis; look for the Armanni-Epstein renal lesion).
      7. Insulin overdose (FA07-38).
      8. Polypharmacy and/or single-medication overdose.
      9. "Poisoning".
      10. Endocrine "storms" or deficits.
        bullethypo- or hyperthyroidism
        bullethypo- or hyperparathyroidism: hyper (FA08-47)
        bullethypo-adrenalism:
        bulletacute septic hemorrhage: Waterhouse-Friderichsen
        bulletrelative adrenal insufficiency in assoc. with other highly stressful disorders
    6. Mimics of sudden cardiac death:
      1. "Cafe coronary"...choking on food.
      2. Acute alcoholic states ("holiday heart").
      3. Acute asthmatic attacks, primarily bronchospasm with relatively little mucus plugging & may require lots of lung sections to diagnose if is a "first asthmatic attack". "Seasoned" asthmatics will usually create quite a stir and be nearly hysterical if they begin to have restricted breathing that is non-responsive...if it is possible to alert anyone, depend on them to do it. People with an asthmatic background can die of other causes and non-natural manners of death...suspect this when no evidence of agitation in the scene investigation.
      4. Air (look for air in atria and/or pulmonary arteries) or amniotic fluid embolism (note squames in pulmonary circulation). A little air or amniotic fluid is not an obligatory killer!
    7. Acute Septicemia:
      1. I autopsied a 12 year old boy who went to bed with a sore throat; found dead the next morning; autopsy essentially negative; postmortem blood culture was positive for group A strep (FA-85-157).
      2. (A-81-617) An 86 year old man dies in 12 hours, jaundiced with fever: undiagnosed bile duct cancer obstruction (emergency surgery could not find it). Undiagnosed colon cancer perforated (FA07-28).
      3. (FA-02-14) A 63 year old male dies at home in 24 hours with flu-like onset; we found an acute bacterial abscess of unknown etiology.
      4. People who have lost their spleens (FA-95-12), even if vaccinated because of it, are liable to odd infections from such as dog bites (the CDC DF-2 bacterium).
    8. Acute anaphylaxis: try to retain frozen serum at 20 degrees C to test for elevated blood tryptase and allergen-specific IgE...larynx need not be edematous.
    9. Intracerebral causes: edema, hemorrhage, tumor (FA91-662), meningitis/encephalitis, trauma (e.g. ice-pick stab)...these findings can sometimes be fairly subtle.
    10. Heat stroke
    11. Acute massive polymyositis: the case I had (A98-15) took 30 days from onset (as if a flu-like illness) to death...so is not really a sudden unexpected death (but you may find one that is even more fulminant).
    12. Severe acute or chronic fatty liver:
      1. Alcoholic: possibly as terminal seizure or an effect on the prolonged QT interval common in chronic alcoholics; DT's if negative blood alcohol; fatal dysrhythmia (A-79-423, FA94-57): markedly enlarged (absolute hepatomegally), highly fatty, glycogen-depleted liver,
      2. Non-alcoholic.
    13. Homicidal asphyxia: with or without significant drug or alcohol levels, associated with suspicious circumstances (look carefully for tiny abrasions over the tip of the nose and for seizure-like bites of tongue and cheek mucosa).
    14. Toxicologic deaths: remember homicidal manner of death masked as accidental drownings of "high" young drug users; carbon monoxide (particularly in the elderly) poisoning [a case example].
    15. Idiopathic seizure disorder with CNS negative and all else negative: remember the lesions that produce syncope and that syncope may produce seizures; everything being negative, then presume a fatal seizure
    16. Morbid obesity...especially where there is a history of sleep apnea and tonsil hypertrophy
    17. Sleep apnea
    18. Senility when >90 years old
    19. Electrocution: 40% of low voltage (e.g., a lamp) cases have no burn; and, victim may even be able to walk into another room before flipping into the terminal dysrhythmia
    20. Trauma with negative findings:
      1. Blows to the head: Dr. Charles "Buddy" Garrett, during his time as a Deputy Medical Examiner in Virginia, told me that he was standing next to an otherwise healthy relatively young male who was being booked in the police station...he became rowdy. A policy officer popped the defendant on the back of the head with a blackjack; the defendant fell to the floor unresponsive and could not be resuscitated. Dr. Garrett, himself, very painstakingly performed the autopsy and could not find any evidence at all of a CNS lesion.
      2. Blows to the chest: these can induce a terminal lethal dysrhythmic disturbance.
    21. Hypothermia/hyperthermia.
    22. Drowning:
      1. When primarily laryngospasm, there can be negative findings of nothing more than suffocation.
      2. While many experts consider that there are no specific markers of drowning, there can be homicidal and suicidal drownings are set up to seem accidental [check out "manner of death"].
    23. Asphyxia:
      1. Soft foods stuck in the posterior pharynx in the elderly, infirm, or physically helpless.
      2. Food/material obstructing, but removed during transport or by resuscitating personnel (medical examiner subsequently not informed of this)...autopsy seems negative.
      3. Prolonged chest compression: such as when apprehended by many people in a crowd; a person compressed in a wreck.
      4. Positional asphyxia (such as someone who is passed out drunk with a tracheostomy and the chin occludes the stoma); or an obese person fainting or passing out wedged head-down.
      5. Gastric contents aspiration: not infrequently being a lethal secondary event (laryngospasm?) triggered by trauma in a "high"/intoxicated individual (FA90-560).
      6. Post obstruction pulmonary edema (POPE): this can happen postoperatively following extubation and onset of an episode of acute laryngospasm and attempts by the patient at respiratory inspiration against a closed glottis (high negative intrathoracic pressure)...or any other mechanism that acutely closes the glottis. The subject has quick onset of foaming reddish frothy pulmonary edema. [FA-04-87].
    24. Pulmonary artery obstruction:
      1. Common pulmonary emboli, see above.
      2. Carcinomatous (A91-911) diffuse micro-occlusions and other types of occlusions not readily visible to the naked eye exam.
    25. Occult severe chronic liver disease:
      1. Hypoglycemic.
      2. Other metabolic derangements.

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(this file begun 7 April 1995; posted 7 Sept. 1998; addition 2 Dec. 2001; latest addition 11 August 2008)

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