Copyright 2002 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.
To the Editor: Catastrophes such as war or earthquake are known to result in increased incidence of sudden cardiac death among survivors, but the physiological mechanisms remain unknown.1 - 2 The events of September 11, 2001, produced psychological distress among large numbers of people who were not physically affected by them. We hypothesized that such stress may lead to autonomic dysfunction, which may be reflected in changes in heart rate variability (HRV). Diminished HRV is associated with an increased incidence of cardiovascular and sudden death in patients both with and without coronary artery disease (CAD).3 - 4
We measured HRV in 12 patients at the Yale-New Haven Hospital who wore 24-hour ambulatory heart monitors during the week of September 11, as well as 12 in control patients who had worn monitors in the preceding 2 months. Control patients were matched for age (within 10 years), sex, presence of CAD or congestive heart failure, and diabetes. Two patients in each group were using β-blockers. Indications for monitoring included palpitations (4 cases, 4 controls), history of or risk for arrhythmia (6 cases, 5 controls), and syncope (2 cases, 3 controls). All patients had been scheduled for heart monitoring prior to September 11. This study was approved by the Yale Human Investigation Committee.
Frequency domain indices of HRV were analyzed using standard power spectrum analysis methods. After editing the R-R interval file to remove ectopic beats and noise, gaps were estimated by interpolated linear splines (recordings with >20% interpolation excluded). The heart rate power spectrum was computed through Fast Fourier Transform and integrated over 5 discrete frequency bands, with high frequency defined as 0.15 to 0.40 Hz.3 Indices of HRV were log-normalized and compared by paired t test.
The logarithm of high-frequency power (a measure of parasympathetic tone) was lower in the subjects monitored after September 11 than in controls (5.54 vs 6.23, P = .047). High-frequency power was lower in 9 of the 12 cases compared with their controls (P = .045). Mean heart rate did not differ between groups (R-R interval: 857 milliseconds [cases] vs 829 milliseconds [controls], P = .64).
We found a decrease in parasympathetic tone during the week of September 11, 2001, which may represent a physiological perturbation among individuals exposed to large-scale psychological stress. Unlike previous studies in which subjects were directly affected by war or natural disaster,1 - 2 the stress experienced by subjects in our study was purely psychological. It is not yet known whether there was increased cardiac mortality or morbidity as a result of the September 11 attacks. Mental stress can induce coronary ischemia2 and can facilitate lethal arrhythmias.5 These changes in cardiac blood flow and rhythm may in turn be caused by alterations in autonomic nervous system function.6 Our data demonstrate that the September 11 attacks may have produced similarly decreased parasympathetic output, which may increase susceptibility to lethal arrhythmias.7
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
Instructions
Comments are moderated and will appear on the site at the discretion of the Journal of American Medical Association editors. Comments should not exceed 500 words of text and 10 references.
Do not submit personal medical questions or information that could identify a specific patient, questions about a particular case, or general inquiries to an author. Only content that has not been published, posted, or submitted elsewhere should be submitted. By submitting this Comment, you and any coauthors transfer copyright to the journal if your Comment is posted.
* = Required Field
Disclosure of Any Conflicts of Interest* Indicate all relevant conflicts of interest of each author below, including all relevant financial interests, activities, and relationships within the past 3 years including, but not limited to, employment, affiliation, grants or funding, consultancies, honoraria or payment, speakers’ bureaus, stock ownership or options, expert testimony, royalties, donation of medical equipment, or patents planned, pending, or issued. If all authors have none, check "No potential conflicts or relevant financial interests" in the box below. Please also indicate any funding received in support of this work. The information will be posted with your response.
Register and get free email Table of Contents alerts, saved searches, PowerPoint downloads, CME quizzes, and more
Subscribe for full-text access to content from 1998 forward and a host of useful features
Activate your current subscription (AMA members and current subscribers)
Some tools below are only available to our subscribers or users with an online account.
Download citation file:
Customize your page view by dragging & repositioning the boxes below.
and access these and other features:
Register Now
Enter your username and email address. We'll send you a reminder to the email address on record.
Athens and Shibboleth are access management services that provide single sign-on to protected resources. They replace the multiple user names and passwords necessary to access subscription-based content with a single user name and password that can be entered once per session. It operates independently of a user's location or IP address. If your institution uses Athens or Shibboleth authentication, please contact your site administrator to receive your user name and password.