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SUDEP and matters of the heart
SUDEP is likely to have a variety of causes. One of them may involve have only minor effects on the QT interval. Valproate has no direct action on dysfunction of the heart due to cardiac arrhythmia which could lead to cardiac repolarization, but can enhance QT prolongation of co-administered insufficient blood circulation and fatal decrease of oxygen supply. Bradycardia drugs which themselves lengthen QT interval and which are metabolized and asystole are well known seizure-related phenomena. In contrast, life- by specific liver enzymes (inhibited by valproate). In contrast, rufinamide, threatening ventricular tachyarrhythmias have been hypothesized for decades primidone and carbamazepine have been reported to shorten QT interval. as a potential cause of SUDEP, but convincing clinical evidence has been To date, the clinical importance of acquired QT shortening is unclear and There are a number of established risk factors of sudden cardiac death Abnormalities of cardiac repolarization are common in people with chronic which increase the susceptibility to ventricular tachyarrhythmias (Surges epilepsy. The question is, however, whether these abnormalities are benign or et al. 2009, 2010). One important risk factor appears to be pathological whether they increase the risk for sudden cardiac death as one plausible cause cardiac repolarization. Cardiac repolarization is the phase of the cardiac for SUDEP. In a recent case report, ventricular tachycardia and fibrillation cycle during which the electrical potential of heart muscle cells returns from were described shortly after a convulsive attack in a person with epilepsy. excitation to the resting condition. The QT interval is an ECG indicator of This woman was successfully resuscitated, and subsequent cardiological cardiac repolarization. Prolongation of the QT interval above normal limits investigations have not shown any underlying cardiac disease, suggesting (which depend on age, gender and actual heart rate) is a well characterized that seizure-related alterations of cardiac excitability may have facilitated the risk factor for sudden cardiac death. Genetic forms, known as long QT life-threatening ventricular tachyarrhythmia in this person. syndromes, are due to mutation in various ionic channels responsible for In summary, there is evidence that abnormal cardiac repolarization and the electrical properties of the heart. Pathological QT prolongation is also ventricular tachyarrhythmia could cause sudden death in some people seen with the use of drugs such as some antibiotics and antidepressants. A with epilepsy. The most important question is whether arrhythmia-related decade ago, a genetic form of abnormally short QT interval, also due to SUDEP can be predicted and prevented. To date, it is difficult to say who mutations in cardiac ionic channels, has been discovered. People with short would benefit from preventive measures, which actions to be taken and at QT syndrome display QT intervals below normal limits, suffer from syncope what time point. Potential measures to reduce the risk or to prevent SUDEP due to atrial fibrillation, ventricular tachycardia and fibrillation, and have a could, however, include anti-arrhythmic medication (such as beta-blockers high risk of sudden cardiac death. QT dispersion is another measure of which are used in some forms of long QT syndrome) and implantation of a cardiac repolarization. It is the difference between the longest and shortest defibrillator device (to stop ventricular tachycardia). Current research focuses QT interval on an ECG recording and reflects the regional heterogeneity of on the risk factors and mechanisms leading to epilepsy-related abnormalities cardiac repolarization. Values above 50-60 ms have been shown to increase in cardiac repolarization. Collaborative multi-centre efforts are needed to the risk of sudden cardiac death in apparently healthy people and in other find out whether these ECG features are helpful to identify people at higher risk for SUDEP and to develop strategies to prevent SUDEP due to cardiac Features of cardiac repolarization have recently been investigated in people with chronic epilepsy. Abnormal QT dispersion was seen in up to one third of people with focal epilepsy. Changes of QT interval during seizures have also been investigated recently. Prolongation of QT interval was found in up to 12% of people with focal epilepsy. Transient abnormal shortening Rainer Surges
of QT interval has been observed to occur with almost every convulsive Department of Epileptology
seizure in people with temporal lobe epilepsy. Antiepileptic drugs seem to University Clinics, Bonn, Germany.
Sudden Unexpected Death in Epilepsy – continuing the global conversation. Chapman, Panelli, Hanna, Jeffs. eds. 2011, Camberwell, Australia. Sudden Unexpected Death in Epilepsy – continuing the global conversation. Chapman, Panelli, Hanna, Jeffs. eds. 2011, Camberwell, Australia.

Source: http://www.sudepglobalconversation.com/files/surges.pdf