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Investigation of Sudden Cardiac Death
Published in Mary N. Sheppard, Practical Cardiovascular Pathology, 2022
The ion channelopathies result from mutations in genes encoding channels or related proteins, altering their properties. A mutation may make a channel non-functional, underactive, overactive or leaky. SCN5A, encodes the alpha subunit of the voltage-gated sodium channel Nav1.5. Nav1.5 regulates the influx of sodium ion, and thus the initiation and propagation of action potentials of the heart. Failure of the channel to close results in LQT type 3, and failure to open causes BrS. The same mutation may cause either within the same family.
Sudden unexpected death in epilepsy
Published in Helen Whitwell, Christopher Milroy, Daniel du Plessis, Forensic Neuropathology, 2021
Christopher Milroy, Daniel du Plessis
There is an increasing realisation that genetic disorders may underlie epilepsy (Tu et al. 2011; Coll et al. 2016; Devinsky et al. 2016). Several genes linked to cardiac channelopathies are also associated with epilepsy. The two entities may overlap (Bagnall et al. 2016). Mutations in the SCN5A and KCNH2 genes have been associated with both long QT syndrome and epilepsy (Klassen et al. 2014). The KCNQ1 gene has been reported in a family with both epilepsy and long QT syndrome (Tiron et al. 2015).
Genetically Determined Ventricular Arrhythmias
Published in Andrea Natale, Oussama M. Wazni, Kalyanam Shivkumar, Francis E. Marchlinski, Handbook of Cardiac Electrophysiology, 2020
Houman Khakpour, Jason S. Bradfield
Disease inheritance is by an autosomal dominant mode of transmission. Loss-of-function mutations in the SCN5A sodium channel were the first and the most well-known cause of BrS, but it only account for about 20% of phenotypic disease. Twelve genes, including mutations in the sodium channel beta subunits, the potassium channel encoded by KCNE3 and the I-type calcium channel (CACNA1C and CACNB2B), have been identified so far.3
Simultanagnosia as the presenting symptom in neuro-ophthalmology
Published in Baylor University Medical Center Proceedings, 2020
Rui Wang, Grant Hopping, Bayan Al Othman, Subhan Tabba, Ashwini Kini, Andrew G. Lee
In case 2, a juxtaposed bilateral homonymous hemianopsia was present due to bilateral parieto-occipital ischemia and thus hypoxic injury to the superior optic radiations. This partly corresponds to “watershed” areas of the brain particularly susceptible to anoxic brain damage. Decreased visual acuity was likely due to bilateral macular involvement. To our knowledge, no cases of simultanagnosia secondary to hypoxic injury of parieto-occipital lobes have been published in the setting of Brugada syndrome. Neuropsychological evaluation showed severe global cognitive decline but only relatively decreased measures of attention efficiency, attention capacity, and working memory. Measures of visual ability were not explicitly reported. Genetic testing showed a heterozygous mutation of the SCN5A gene, which encodes the alpha subunit of the main cardiac sodium channel. This gene is the most common mutation associated with Brugada syndrome but is also associated with long QT interval, type 3 dilated cardiomyopathy, and atrial fibrillation. Brugada syndrome is a common genetic cause of sudden unexpected cardiac arrest by predisposing otherwise healthy young adults to ventricular arrhythmia.5 Testing of the proband might help identify other at-risk relatives who might benefit from prophylactic automatic implantable cardioverter-defibrillator placement.
Recent advances in the treatment of Brugada syndrome
Published in Expert Review of Cardiovascular Therapy, 2018
Mariana Argenziano, Charles Antzelevitch
The implantation of an implantable cardioverter defibrillator (ICD) is accepted as first-line therapy for prevention of SCD in high-risk BrS [165,166]. It is important to recognize, however, that ICDs can be associated with many complications, especially in young active individuals [70,167,168]. At 10 years post-implant, the rate of inappropriate shock and lead failure have been reported to be 37% and 29%, respectively. Remote monitoring can identify lead failure and avoid inappropriate shocks [169]. BrS patients with a first arrhythmic event documented after prophylactic ICD implantation exhibit their arrhythmic event at a later age with a higher incidence of positive family history of SCD and SCN5A mutations compared to those presenting with an aborted cardiac arrest. Subcutaneous ICDs (S-ICDs) are being considered for this indication in that they are expected to be associated with fewer complications over a lifetime [170,171].
Brugada syndrome and the story of Dave
Published in Neuropsychological Rehabilitation, 2018
Samira Kashinath Dhamapurkar, Barbara A Wilson, Anita Rose, Gerhard Florschutz
Brugada syndrome (BrS) is a rare, autosomal dominant genetic condition associated with unexpected cardiac death in young individuals (Moreno et al., 2014). It is associated with alterations in the SCN5A gene, of which nearly 300 mutations have been described (Kapplinger et al., 2010). At present 19 different genes has been identified which are associated with Brugada phenotype (Antzelevitch & Patocskai, 2016). It is characterised by abnormal electrocardiogram (ECG) findings. Although such findings were found prior to this in survivors of cardiac arrest, it was only in 1992 that the Brugada brothers recognised these ECG findings were part of a distinct clinical entity causing sudden death because of ventricular fibrillation and a potentially lethal arrhythmia in the heart (Brugada & Brugada, 1992).