4: Sudden Death Flashcards
Define sudden cardiac death.
- Unexpected death due to cardiac cause
- Occurs within 1 hour of symptom onset
Role of autopsy in SCD
- Cause of death
○ Distinguishes cardiac from non-cardiac causes
○ Determines nature of cardiac disease- Family
○ Identifies inherited cardiac conditions
○ Prompting screening and counselling of family
○ Identifies reportable infectious diseases
○ Prompting prophylactic treatment of close contacts
○ Provides family with answers and helps grieving process - Manner of death
○ Distinguishes natural from unnatural causes
○ Identifies involvement of toxic or illicit drugs - Public health
○ Identifies public health risk and disease trends
○ Provides epidemiologic data to control disease outbreaks
- Family
Common causes of sudden death
- Non-cardiac causes ○ Respiratory § Asthma attack § PE § Asphyxia § Pneumothorax ○ Nervous § SUDEP § CNS haemorrhage § CNS infection § Cerebral oedema ○ GI § GI haemorrhage ○ Endocrine § Endocrinopathies - Cardiac ○ Coronary artery disease § Atherosclerosis § Anomalous coronary origin § Coronary spasm § Dissecting aneurysm § External compression ○ Channelopathies § Long/short QT syndrome § Brugada syndrome § Early repolarise syndrome § Wolff-Parkinson-White syndrome ○ Cardiomyopathies § Alcoholic § Hypertrophic § Idiopathic § Obesity-related § Fibrotic § Arrhythmogenic right ventricular § Myocarditis ○ Other § Systolic heart failure § Aortic stenosis § Tetralogy of Fallot
What relevant information should the pathologist requires prior to autopsy?
- Patient details ○ Age ○ Sex - Presenting complaint ○ Time of death ○ Place of death ○ Circumstances of death ○ Witnesses ○ Scene findings - Hx of presenting complaint ○ Time interval after symptom onset ○ Previous symptomatology - Past medical history ○ Past medical and surgical history ○ Clinical investigation results - Drug history ○ Prescribed drugs ○ OTC drugs ○ Recreational drugs ○ Allergies - Social history ○ Smoking ○ Alcohol ○ Lifestyle - Family history ○ ICDs ○ Pacemakers ○ Transplants ○ Sudden death ○ Similar presentation
What samples are typically collected at autopsy and what investigations may be requested?
- Hair ○ Toxicology - illicit drug use - Bile ○ Tox - Peripheral venous blood ○ Tox ○ Genetic analysis - inheritable disorders ○ Microbiology - infection ○ Virology - infection - Serum ○ Tox ○ Biochem - anaphylaxis - Urine ○ Tox ○ Biochem - Vitreous humour ○ Tox ○ Biochem - troponin, electrolytes, glucose - Coronary artery ○ Immunohistochemistry - ischaemia - Pericardial / cerebrospinal fluids ○ Tox ○ Biochem - Heart / spleen ○ Genetic analysis ○ Micro ○ Virology - Gastric contents ○ Tox - Others ○ Tox ○ Electron microscopy - metabolic disorders
How does the severity of coronary artery disease affect the cause of death?
- Atherosclerosis often present - incidental finding
- Significant if 75% +
What causes Brugada syndrome?
- Disorder characterised by sudden death associated with incomplete right bundle-branch block and ST elevations on precordial lead
- SCN5A mutation
- Reduced intracellular Na
- Late depolarisation on action potential
- Concave ST elevation followed by ST depression in V1
Characteristic features of Brugada syndrome
- Concave ST elevation followed by ST depression in V1
- Symptoms
○ Palpitations
○ Syncope
○ Sudden death
- Symptoms
Pathophysiology of long QT syndrome
- Congenital disorder characterised by prolongation of QT interval on ECG
- Propensity to ventricular tachyarrhythmias
- LQTS 1
○ KCNQ1 mutation
○ Reduced intracellular K+
○ Prolonged repolarisation on action potential
○ Broad T wave on ECG - LQTS 2
○ KCNH2 mutation
○ Decreased intracellular K+
○ Prolonged repolarise on action potential
○ Bifid T wave on ECG - LQTS 3
○ SCN5A mutation
○ Increased intracellular Na+
○ Prolonged repolarise on action potential
○ Late T wave on ECG - Acquired causes
○ Drugs
§ Antiarrhythmics - amiodarone
§ Antihistamines
§ Antibiotics - erythromycin
§ Antimalarial - chloroquine
§ Psychotropics - SSRIs, TCAs, haloperidol
§ Narcotics - methadone
○ Metabolic
§ Hypocalcaemia
§ Hypokalaemia
§ Hypomagnesaemia
○ Other
§ Acute MI
§ Myocarditis
§ SAH
Hypothermia
Presentation of long QT syndrome
Palpitations
Syncope
Sudden death
What can trigger long QT
- LQTS 1 ○ Exercise ○ Shock ○ swimming - LQTS2 ○ Loud noise ○ Pregnancy - LQTS3 ○ Fatigue
Name left-to-right shunts
Atrial septal defect
Patent foramen ovale
Ventricular septal defect
Patent ductus arteriosus
Features of atrial septal defect
○ Abnormal fixed openings in atrial septum allowing communication of blood between left and right atria
○ Mostly asymptomatic till adulthood
○ May be found incidentally
§ Enlarged right ventricle on CXR
○ Can cause dyspnoea, arrhythmias especially AF
○ Managed surgically or use catheter to fix with implant
○ Secundum (90%) result from deficient septum secundum formation near centre of atrial septum
§ Not usually associated with any other anomalies
§ Any size
§ Multiple of fenestrated
○ Primum occur adjacent to AV valves
§ Often associated with AV valve abnormalities of VSD
○ Sinus venosus defects located near entrance to superior vena cava
§ Associated with anomalous pulmonary venous return to right atrium
Features of patent foramen ovale
○ 80% close by 2 years of age
○ Rest form unsealed flap that can cause transient R->L shunting when pressure in right heart increases
§ Sneezing, coughing, straining
○ Present in paradoxical embolism
○ Can be close percutaneously in those with recurrent TIAs
Features of ventricular septal defect
○ 90% occur in membranous interventricular septum
○ 10% below pulmonary valve - infundibular VSD
○ In children commonly exist with other anomaly
○ Few effects if small of close spontaneously (50%)
○ Significant effects if large
§ L-R shunting, RV hypertrophy, pulmonary hypertension, shunt reversal, cyanosis
Features of patent ductus arteriosus
○ Usually closes 1-2 days after both and obliterates over months to ligamentem arteriosum
§ In response to increased arterial oxygenation, low pulmonary vascular resistance, low PGE2
○ 90% isolated
○ Prostaglandin and prostaglandin inhibitor therapy
Right-to-left shunts
Tetralogy of Fallot
Transposition of the great arteries
Tricuspid atresia
Features of Tetralogy of Fallot
○ VSD, subpulmonic stenosis, aorta overriding VSD, RV hypertrophy
○ Boot shaped heart
○ 1/2000 births
○ Clinical features
§ Most infants cyanotic at birth
§ Obstruction proportionally worse with growth
§ Ventricular failure rare
Features of transposition of the great arteries
○ Produces ventriculoarterial discordance
○ Most common variant = dextro-TGA
§ Aorta arises from right ventricle
§ Pulmonary artery emerges from left ventricle
§ Atrium-to-ventricle connections normal
○ Complete TGA items from abnormal function of spiralling truncal and aortopulmonary septae
§ Separation of systemic and pulmonary circulations
§ Incompatible with life unless shunt present
Features of tricuspid atresia
○ Complete occlusion of tricuspid valve orifice
○ Arises from unequal division of AV canal
§ Mitral valve larger than normal
§ Right ventricular hypoplasia
○ Circulation maintained by right to left shunting through ASD or patent foraemen ovale
○ Cyanosis present form birth
○ High early mortality
Constrictive cardiac lesions
Coarctation of the aorta
Pulmonary stenosis and atresia
Aortic stenosis and atresia
Features of coarctation of aorta
○ M:F = 2:1
○ Infantile form
§ Symptomatic in early childhood
§ Tubular hypoplasia of aortic arch proximal to PDA
○ Adult form
§ Discrete ridgelike infolding of aorta just opposite closed ductus arteriosus distal to arch vessels
○ Encroachment of aortic lumen variable
50% of cases associated with other abnormalities
Features of pulmonary stenosis and atresia
○ Obstruction at level of pulmonary valve
○ Hypertrophy of RV
○ Blood jets through narrow valve and injuries vessel to cause post-stenotic dilation of pulmonary arteries
○ Spectrum of severity from survival without treatment to needing surgery
○ Atresia requires PDA/ASD
Types of aortic stenosis and atresia
○ Valvular
§ Abnormally small (hypoplastic), thick (dysplastic) or wrong number
○ Sub valvular
§ Dense ring of fibrous tissue below the cusps
○ Supravalvular
§ Aortic wall is thickened and narrowed. Failure of development due to elastin gene mutations
