A fundamental discovery reported today (February 23) in Nature uncovers the first molecular evidence linking the body's natural circadian rhythms to sudden cardiac death.
Ventricular arrhythmias, or abnormal heart rhythms, are the most common cause of sudden cardiac death: the primary cause of death from heart disease. They occur most frequently in the morning waking hours, followed by a smaller peak in the evening hours. While scientists have observed this tendency for many years, prior to this breakthrough, the molecular basis for these daily patterns was unknown.
The discovery will be the first step towards new diagnostic tools and therapies to prevent or treat the occurrence of this fatal event.
The research team led by Case Western Reserve University School of Medicine discovered that a novel genetic factor, Kruppel-like Factor 15 (KLF15), links the body's natural circadian rhythm to, and regulates the heart's electrical activity. A lack or excess of KLF15, causes a loss or disruption in the heart's electrical cycle and greatly increases susceptibility to arrhythmias.
A lack of KLF15 is seen in patients with heart failure, while its excess causes electrocardiography (ECG) changes such as those seen in patients with Brugada syndrome, a genetic heart rhythm disorder.
"Our study identifies a hitherto unknown mechanism for electrical instability in the heart. It provides insights into day and night variation in arrhythmia susceptibility that has been known for many years," said Darwin Jeyaraj, the lead author of the study and an assistant professor of medicine at Case Western Reserve University School of Medicine.
Sudden cardiac death due to electrical instability is the leading cause of death in the United States – 700-800 deaths per day. It accounts for 10,460 (75.4 per cent) of all 13,873 cardiac disease deaths in persons aged 35-44 years old in the U.S.
With this understanding, scientists can propose new patient treatments with the goal of reducing incidences of sudden cardiac death.
This landmark finding proves that circadian rhythms are an important factor in sudden cardiac death. In addition, it raises the possibility that additional factors may affect the occurrence of sudden cardiac death. Further studies are needed to examine the how additional components of the biological clock can affect electrical stability in the heart.
Keywords: cardiac death, health issues
I think Madhu should have quoted atleast some study which says that doing a TMT is beneficial in asymptomatic healthy patient.There are ample of evidence that doing anykind of cardiac tests in asymptomatic patients has no change in the outcome. It's just money minded corporate hospitals are doing all these cardiac tests for healthy persons, so far no scientific base for it. I don't know how TMT with less than 30% sensitivity and specificity helps in predicting ischemia in an asymptomatic patients.Suppose if you do a TMT and if it is negative can we say the patient you don't have heart disease. The same thing is applicable for ECG and Echo. In a patients who doesn't have cardiac sympttoms what is the chance of an Echocardiogram picking up a diagnosis more than a history and clinical examination..Regarding Ventricular arrhythmias a lot can be done in India, such as medications, Implanting an ICD (special pacemaker) and VT ablation procedures.
Thank you Ved Anarish for your reply .what you have written is correct to an extent.But there are diseases like ischemic heart diseases{IHD}and Heart valve problems which can be easily diagnosed with non invasive procedures like ecg,tmt and ecocardiogram ,and all the above mentioned tests are not counter productive also.So these tests are advisable incase of any health check up one requires
In reply to Madhu's suggestion
This is Heart Month in US. American Heart Association has advised
against any any test in the absence of chest pain and shortness of
breath.
Any amount test without having any of the two symptoms is useless and
could be counter productive. Should not be done.
The circadean or the biological clock is a 24 hr cycle of biological, physiological & behavioural processes in all living beings. In the mammals, biological clock is located in supra chiasmatic nuclei of the hypothalamus (antr) of the brain. Though the rhythms are endogenous,they adjust to external cues: Eg--light travels thro' the eyes, ,retinohypothalamic tract, suprachiasmatic nuclei to pineal gland which gets info from retina thro' these nuclei , secretes melatonin in response. Melatonin is involved in sleep-wake cycle.
Possible role of biological clock in bipolar didease is being studied, focussing on the genes affecting its behaviour.
Very good article to read,Though Ventricular arrhythmia are the most common cause of death ,we can't rule out the other causes ,in fact most of the disease's of heart are unpredictable what we can do is routine check up at least once in a year will help to identify symptoms in the early stage.tests like e.c.g,t.m.t and eco cardiogram can give almost a correct picture of the functioning of the heart.Early detection will reduce the complications to a greater extent.
Well, what could be the solution to correct the Ventricular arrhythmias, or abnormal heart rhythms? Even seeing a heart specialist didn't give us a solution to the above.
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