In the wake of last week’s catastrophic earthquake in China, we can only imagine the trauma that the victims and their families went through – trauma that will probably stay with them for the rest of their lives. With such trauma comes psychological stress and with increased stress comes elevated cardiovascular risk.
Several research studies have investigated the effect of acute stressors such as catastrophes and natural disasters on the cardiovascular well-being of the victims and people in the vicinity. A review article by Dr. JE Dimsdale of the University of California at San Diego shows that many of these studies observed an increased cardiovascular risk after earthquakes.
Several specific studies were conducted in conjunction with specific incidents, as follows:
In 1994, on the day of the Northridge, California earthquake, the numbers of deaths due to cardiovascular events was significantly higher compared to the same date in previous years.
During the Hanshin-Awaji earthquake in Japan in 1995, the blood pressure of many patients increased, and didn’t lower at night time as blood pressure normal does – the so-called the nocturnal “dip” in blood pressure.
Another study coincided with the 1999 earthquake in Taiwan. Twelve patients were at that time being routinely studied with Holter monitoring. Results of the Holter monitor were examined and showed dramatic differences between the readings minutes before and minutes after the earthquake. There were pronounced increases in heart rate at the time of the quake of up to 160 beats per minute. However, it’s not only the heart rate that changed abruptly.
“Perhaps more interesting was the observation that the HR variability itself changed, with a relative drop in high-frequency variability and an increase in the low-frequency/high-frequency ratio, denoting relative withdrawal of parasympathetic nervous system activity and an increase in sympathetic nervous system (SNS) activity. These changes were attenuated in patients who were receiving beta-blockers.”
In 2004, Japan was again hit, this time in the Central Nigata area. In total, 3 strong earthquakes and 90 after-shocks occurred in a period of 1 week. During this period, a dramatic increase in incidence of pulmonary embolism was observed.
“The underlying mechanism for [the increased cardiovascular] risk is unclear. Given the emergency conditions surrounding a massive earthquake, it is difficult to conduct fine-grained experimental or epidemiologic studies. Thus, it is not known how much of the risk is conveyed by the emotional trauma acting alone versus factors like forgetting to take routine medications, living in cramped emergency quarters, facing disrupted sleep, and so on. Given the chaos surrounding massive disasters, it is unlikely that such data would ever be gathered.”
The moral lesson of these stories is that acute stressors – which can come in many different forms, including earthquakes – affect our health almost immediately. This knowledge can help us and our doctors in the control and management of cardiovascular events during stressful times.
Dimsdale, J E. Psychological Stress and Cardiovascular Disease. Journal of the American College of Cardiology. Medscape 6 May 2008