The investigation of sudden arrhythmic death syndrome (SADS)-the current approach to family screening and the future role of genomics and stem cell technology

Long QT syndrome and sudden unexpected infant death

Long QT syndrome (LQTS) is an inheritable primary electric disease of the heart characterised by abnormally long QT intervals and a propensity to develop atrial and ventricular tachyarrhythmias. It is caused by an inherited channelopathy responsible for sudden cardiac death in individuals with structurally normal hearts. Long QT syndrome can present early in life, and some studies suggest that it may be associated with up to 20% of sudden unexplained infant death (SUID), particularly when associated with external stressors such as asphyxia, which is commonly seen in many infant death scenes. With an understanding of the genetic defects, it has now been possible to retrospectively analyse samples from infants who have presented to forensic pathology services with a history of unexplained sudden death, which may, in turn, enable the implementation of preventative treatment for siblings previously not known to have pathogenic genetic variations. In this viewpoint article, we will discuss SUID, LQTS and postmortem genetic analysis.

Two Sudden and Unexpected Deaths of Patients with Schizophrenia Associated with Intramuscular Injections of Antipsychotics and Practice Guidelines to Limit the Use of High Doses of Intramuscular Antipsychotics

Intravenous haloperidol has been associated with torsades de pointes (TdP). These two sudden deaths were probable adverse drug reactions (ADRs) following intramuscular (IM) antipsychotics. The autopsies described lack of heart pathology and were highly compatible with the possibility of TdP in the absence of risk factors other than the accumulation of antipsychotics with a high serum peak after the last injection, leading to death within hours. The first case was a 27-year-old African-American male with schizophrenia but no medical issues. His death was probably caused by repeated IM haloperidol injections of 10 mg (totaling 35 mg in 2 days). The second case involves a 42-year-old African-American female with metabolic syndrome. Her probable cause of death was the last ziprasidone IM injection of 20 mg in addition to (1) three extra haloperidol doses (2 hours before the ziprasidone injection, 5 mg oral haloperidol; approximately 21 hours earlier, 5 mg oral haloperidol; and 2 days prior, one 10 mg IM haloperidol injection), (2) 10 mg/day of scheduled oral haloperidol for 6 days before death, and (3) a long-acting paliperidone injection of 156 mg 18 days before death. The study of haloperidol glucuronidation and its impairment in some African-Americans is urgently recommended.

Exploring the Discussion of Risk of Sudden Cardiac Death

Sudden arrhythmic death syndrome (SADS), where death is secondary to cardiac arrhythmia, is associated with several cardiac ion channelopathies, including long QT syndrome and Brugada syndrome, as well as cardiomyopathies such as hypertrophic cardiomyopathy and dilated cardiomyopathy. Many of these conditions often present in childhood or adolescence. This study investigates how diagnoses of cardiac diseases associated with SADS are communicated within families. A questionnaire was distributed through cardiac disease-focused support groups and organizations. Data from 114 parents who have a child with a SADS condition were used for analysis. Based on the responses, parents explained the risk of SADS in a straightforward manner and related the risk to the importance of compliance with the prescribed treatment. Participants also found it difficult to determine and enforce lifestyle modifications, manage individuals' emotional reactions, convey the seriousness of the information without scaring their children, and discuss the risk of SADS during these conversations. Concerns regarding disease progression, length and quality of life, and treatment failures were also expressed. Healthcare providers, the Internet, other affected people, visual aids, and personal experience were all reported to be helpful for facilitating these discussions. Services and resources requested by participants included children's support groups, a counselor or psychologist, and child-oriented materials. Increased understanding of how families discuss children's diagnosis of SADS conditions will equip healthcare providers with the information to address parental concerns and help facilitate meaningful and informative discussions within families.

Effective cascade screening through identification of a mutation in RYR2 in a large family with a history of sudden death

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disorder which usually presents in the first or second decade of life with syncope, which is typically induced by emotional stress or exercise. We describe a large family with a history of three sudden unexpected deaths. Investigations in the sibling of a deceased individual affected by emotion-induced syncope revealed ventricular bigeminy. Molecular genetic testing was performed on one symptomatic individual and a missense mutation in RYR2 was identified consistent with a diagnosis of CPVT. Subsequent cascade testing of family members excluded 37 of 43 individuals from risk and facilitated preventative intervention. This case highlights the value of genotyping in sudden cardiac death by defining the precise diagnosis and through the identification and exclusion of at-risk individuals. <Learning objective: The diagnosis of CPVT should be considered in families with a history of sudden death in a previously asymptomatic young person. Cascade molecular genetic testing should be undertaken as, if a pathogenic mutation is found, this can distinguish it from other arrhythmogenic disorders and can identify at-risk individuals allowing treatment to be targeted at those in need, thus helping to reduce the mortality associated with the condition.>.

A case control study on autopsy findings in sudden unexplained nocturnal death syndrome

AIM

Sudden unexplained nocturnal death syndrome (SUNDS) has been linked to the Brugada syndrome. In some places, acute haemorrhagic pancreatitis is widely held to cause it. We conducted a systematic, controlled autopsy study on Filipino SUNDS victims to rule out structural heart findings as well as acute haemorrhagic pancreatitis as causes.

METHODS AND RESULTS

A case control autopsy study was conducted comparing SUNDS victims between 18 and 50 years of age who died within 1 h of symptom onset with age- and gender-matched controls. There were 24 SUNDS (mean age 34.5 years) and 24 controls (mean 32.7 years). The autopsy incidence of structural heart disease was 8.3% (95% CI (1% to 27%)) and focal pancreatic haemorrhage was 4.17% (95% CI (0.1% to 20%)) but zero for true acute haemorrhagic pancreatitis among SUNDS victims. Autopsy findings in SUNDS versus controls were not significantly different from each other, showing no diagnostic abnormality in any of the organs. There was no significant difference in the incidence of acute haemorrhagic pancreatitis in both the SUNDS and control groups. We did not find fetal dispersion of the atrioventricular (AV) node, sclerosis or fibrosis of the AV conduction system, in a substudy of SUNDS cases.

CONCLUSIONS

We have shown that there is no significant difference in the overall autopsy findings between SUNDS and controls. Autopsy findings were normal in 70% of SUNDS; no cardiac structural pathology was found in 87% of cases. Haemorrhagic pancreatitis is the cause of death in a minority of SUNDS. The cardiac conduction system is normal in a subgroup of SUNDS studied.