Hibernation and stunning of the myocardium

Article Abstract:

In the December 26, 1991 issue of The New England Journal of Medicine, physicians report an unusual case involving complications after a heart valve replacement. The case illustrates two interesting aspects of heart disease, hibernation and stunning. Heart attacks and angina can result from the blocking of a major coronary artery. It had been thought in the past that there were two possible outcomes of such blockages: permanent damage or reversible ischemia. The ischemia, or oxygen deprivation resulting from inadequate blood flow, may result in the death of heart muscle cells if the blood flow is not restored in time. This is, of course, an infarction. The other possibility is the timely restoration of blood flow. It is now appreciated that heart muscle cells can hibernate. This term has been whimsically chosen to indicate that heart muscles can reduce their activity, and therefore their oxygen requirements, during chronic ischemia. The hallmark of hibernation is that the muscle cells, and heart function itself, wake up when ischemia is relieved. Hibernation was first hypothesized to explain the rapid improvement in heart function observed in some patients after coronary bypass surgery. Stunning is a related phenomenon. Stunned heart muscle does not recover as rapidly as hibernating heart muscle. But in contrast with infarcted heart muscle, in which many muscle cells are dead, it does indeed recover. Function in the stunned heart muscle may not return for 10 to 16 days after the restoration of blood flow. The effects of stunning may be seen when thrombolytic therapy is used in the treatment of heart attack victims. Thrombolytic therapy dissolves the blood clots that are blocking major heart arteries. The absence of immediate improvement in heart function does not indicate that the thrombolytic therapy has failed. If the muscle is stunned, the improvement may be gradual even after the blood flow within the heart muscle has been restored. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Heart, Ischemia, Coronary arteries, Hibernation

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Sudden cardiac death triggered by an earthquake

Article Abstract:

Emotional stress may bring on sudden cardiac death in people predisposed to atherosclerotic cardiovascular disease. Researchers examined coroner records at the time of the Northridge earthquake that struck Los Angeles on January 17, 1994. The death rate from cardiac arrest rose from an average of 5 per day the week before the earthquake to 24 deaths on January 17, 1994. Mortality rates fell sharply to 3 per day during the six days after the earthquake. On the day of the disaster, coroner records indicated 51 of 101 deaths had occurred as a result of underlying heart disease. Twenty-nine people died from trauma. Age and sex characteristics were similar to those of other groups of people who died during 1991, 1992, and 1993. Since only five deaths from cardiac arrest could be expected to occur on the day of the earthquake, the additional 19 deaths can be attributed directly to the earthquake.

Stress (Physiology)

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Triggering of sudden death - lessons from an earthquake

Article Abstract:

Extreme stress may trigger sudden cardiac death at a rate much above the daily average. Researchers found that the number of deaths from cardiac arrest was five times higher than normal on the day of the 1994 Northridge earthquake in Southern California. About 40% of deaths may be related to sudden provocation, such as fear or abruptly waking up during an earthquake. Emotional reaction rather than physical exertion seems to be a risk factor for heart beat irregularities and possible death. Medical research is in a unique position to investigate the triggers surrounding sudden cardiac death after natural disasters. Stress at any level seems to contribute to heart attack and death. It may be possible to use ultrasound to identify those tissues most likely to rupture, followed by special attention to risk factors and appropriate treatment.

Stress (Psychology)

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