HEALTH CORNER

DEBASHISH GANGOPADHYAY | Monday November 19, 2007 00:00

Scientific research suggests this happens when stress hormones or adrenaline released by the nervous system in preparation for 'fight or flight' bombard the heart, causing a lethal toxic rush.

It is well known that mild stress or fright can cause shortness of breath and irregular heart rhythms, or arrhythmias. But the potentially lethal effect of the brain on the heart has remained on the fringes of medical research. Intense emotional reactions-including fear, anger, shock, grief, and even relief (or conditions such as brain hemorrhage)- can deluge the heart with adrenaline, causing cells to die and contraction bands to appear on the organ. In extreme cases, such a 'nervous system storm' can trigger severe damage, leading to an abrupt cessation of life (sudden death).

The term 'voodoo death' is a reference to a 1942 article by the anthropologist Walter Cannon, who recounted how witch doctors frightened people to death in aboriginal cultures merely by pointing a bone or casting a 'spell'. In reality, Cannon wrote, it was the victim's own belief in the power of the bone to kill, that did them in. The 'voodoo' death thesis is relevant to today's medicine because the circumstances of brain-heart interaction are not well understood, and in stressful situations, these interactions can potentially kill anyone. Everyone is at risk, but 99.99 percent of people, under acute life-threatening stress, don't die.

Recent studies provide relevant evidence that psychological stress significantly influence the pathogenesis of sudden cardiac death. Psychological stress expresses a situation of imbalance, derived from a real or perceived disparity between environmental demands and the individual's ability to cope with these demands. A situation of psychological stress may include different components: personality factors and character traits, anxiety and depression, social isolation and acute or chronic adverse life events. In particular, it has been documented that a sudden extremely hard event, such as an earthquake or a war strike, can significantly increase the incidence of sudden death. Sudden death occurs when transient disruption (such as acute myocardial ischaemia, platelet activation or neuroendocrine variations), occurring in a patient with a diseased myocardium (such as one with post-necrotic scar or hypertrophy), triggers a malignant arrhythmia. 

Psychological stress acts at both levels: by means of a 'chronic' action it contributes to create the myocardial background, while by means of an acute action it can create the transient trigger precipitating sudden death. In the chronic action, two possible mechanisms can be detected: the first is a direct interaction, which contributes to cause a hypertension status or to exacerbate coronary atherosclerosis consequent to endothelial dysfunction; the second one acts through adverse health behaviours, such as poor diet, excessive alcohol consumption or smoking. In case of acute psychological stress, the mechanisms involved are mainly the ability to trigger myocardial ischaemia, to promote arrhythmogenesis (irregular movements of the heart), to stimulate platelet function, and to increase blood viscosity. Finally, some individuals have a sympathetic nervous system hyper-responsitivity, manifesting as exaggerated heart rate and blood pressure response, which result in accelerated atherosclerosis.

The idiopathic long QT syndrome (LQTS) represents a unique clinical example of stress-related sudden cardiac death. LQTS is characterized by the association of several distinctive electrocardiographic features, among which prolongation of the QT interval is the best known, with life-threatening arrhythmias (irregular movements of the heart) that usually occur under conditions of physical or psychological stress. Effective therapies exist and are represented by antiadrenergic interventions; beta-adrenergic-blocking agents are the treatment of choice.

The stressors more frequently associated with syncopal events in LQTS patients include fear, exercise fraught with emotions, swimming, and awakening because of loud noise.

Sudden Death from Stress Linked to Wonky Signals in the Brain
Sudden cardiac death from emotional stress may be triggered by uneven signals from the brain to the heart, according to a study by University College London (UCL) scientists.

UCL researchers have discovered that a system which normally coordinates signalling from the brain to different parts of the heart may be disrupted in some people, making them vulnerable to potentially fatal abnormal heart rhythms during mentally taxing tasks or emotional events such as family gatherings.

This is particularly true of people who already have heart disease, but it is the brain that may be most responsible. The new study suggests that uneven brain activity, in a region where nerves link directly to the heart, seem to result in an uneven distribution of signals across the heart, which stops the heart from contracting normally.