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Blackouts and near drownings may signal sudden death risk

Blackouts and near drowning events may signal an increased risk of sudden death, according to research presented at the South Africa Heart Congress 2015, held recently in Rustenburg, South Africa

Blackouts and near drowning events may signal an increased risk of sudden death, according to research presented at the South Africa Heart Congress 2015, held recently in Rustenburg, South Africa

Numerous patients with long QT syndrome (LQTS) in South Africa share the same causal KCNQ1/A341V mutation, which can all be traced to a common founder couple of Dutch descent in the early 18th century. The current study was set up in the early 1990s to document the founder effect and later expanded to study modifiers of severity.

Through cascade screening of relatives of 26 LQTS index cases, researchers identified 203 living patients with the KCNQ1/A341V mutation. Nearly four in five (79%) of the mutation carriers had experienced blackouts. Only 26% of the patients had been diagnosed with LQTS initially and given appropriate treatment, while 40% were incorrectly diagnosed with epilepsy and 34% were given incorrect laymen’s or medical explanations such as drowning or sick sinus syndrome.

Some 23 patients died before the age of 20 years. Half “drowned” despite being able swimmers. A 13 year old girl died on a skating rink while being treated for epilepsy and a five year old boy “choked on water”.

Co-author Professor Paul Brink (University of Stellenbosch, Tygerberg, South Africa) said: “LQTS is a cardiac disorder associated with syncope. It is a treatable cause of sudden death but unfortunately blackouts, being common and most often not serious, are often ignored and the small group with serious events are then missed. When presenting to medical services the underlying cause may also be misdiagnosed.”

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Professor Paul Brink (University of Stellenbosch, Tygerberg, South Africa)

“Our research shows that many patients with LQTS never see a doctor, or when they do, they are given an inaccurate diagnosis,” added Professor Brink. “The most common misdiagnosis in living patients was epilepsy, while in those who died it was drowning.”

“It is astonishing how many patients do not take blackouts, especially if infrequent, seriously…to make matters worse, people frequently do not realise that death during a blackout is a harbinger of similar risk to surviving relatives,” he added.

“Sudden deaths can be prevented if people recognise unusual fainting events and take action. Fainting at the sight of blood is harmless but a blackout during activity is cause for further investigation. The same goes for drownings or near drownings. If someone suddenly stops swimming during a competition and floats lifeless this is obviously not a typical drowning,” Professor Brink concluded.

…and sniffing and gasping can prevent syncope

Sniffing and gasping can prevent fainting, according to research presented at Acute Cardiovascular Care 2015, held recently in Vienna, Austria.1

The study included two women aged 56 and 62 years with a history of vasovagal syncope. The head-up tilt test was performed on each patient. At the moment blood pressure began to drop, patients were asked to sniff or gasp twice with their mouths closed and then breathe out. The researchers found that blood pressure and heart rate did not drop and syncope was avoided.

These two cases confirmed the sympathomimetic effect of voluntary equivalent of the aspiration reflex, the authors say. Voluntary sniffs can therefore be recommended for prevention of reflex syncopes, they conclude.

Lead author Dr Marta Bavolarova (Louis Pasteur University Hospital, Kosice, Slovak Republic) said: “Recurrent syncope has serious effects on quality of life. Patients are often injured when they fall, which reduces their mobility and ability to look after themselves. Depression is common in these patients.”

“We believe that sniffing and gasping have a strong sympathetic effect that inhibits the abnormal parasympathetic activity in these patients,” Dr Bavolarova added. “This stops fainting at the highest level.”

She concluded: “Patients with recurrent fainting are advised to avoid standing up quickly and standing for long periods of time. Those who have prodromal symptoms like weakness, sweating or visual disturbances are advised to do counterpressure manoeuvres like leg crossing and hand grips to increase their heart rate and blood pressure. We now also tell patients that they can sniff or gasp to prevent themselves from fainting. This was a small preliminary study and we will confirm our findings in a larger number of patients.”

References

1. Blackouts and sudden death in the apparently well and young – the case of Long  QT Syndrome: missed opportunities for a diagnosis and treatment. Presented during: Abstract Presentation – Adult Cardiology, on 27 October by Professor Paul Brink.

2. Reversal of various reflex syncopes in patients by voluntary sniffs or gasps. Presented during: Poster Session 2 – Syncope, on 17 October by Dr Marta Bavolarova. Abstract available here: http://spo.escardio.org/SessionDetails.aspx?eevtid=1101&sessId=16794&subSessId=4902&searchQuery=%2fdefault.aspx%3feevtid%3d1101%26days%3d%26topics%3d%26types%3d%26rooms%3d%26freetext%3dbavolarova%26sort%3d1%26page%3d1%26showResults%3dTrue%26nbPerPage%3d20%25#.Vi-ETKTlJIg

Published on: October 30, 2015

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