Yale Bulletin and Calendar

May 26, 2000

Volume 28, Number 33

Researcher links unexplained car
accidents and heart irregularities

One driver crashed into a stone wall; another regained consciousness to find her car dangling on a precipice; and a third motorist was told when he awoke from a month-long coma that his "suicide attempt" had failed.

All of these patients lost consciousness while driving because they suffered from heart arrhythmias or other cardiac irregularities, says Dr. Mark Schoenfeld, associate clinical professor of internal medicine at Yale School of Medicine.

"We're actually almost seeing this in epidemic proportions," says Schoenfeld, who also directs a program on cardiac electrophysiology. He presented his findings at a recent meeting of the North American Society of Pacing and Electrophysiology in Washington, D.C.

Schoenfeld and his colleagues studied 54 consecutive patients referred to the electrophysiology service over a 14-year period. Each patient had lost consciousness while driving, but no one knew why. None showed any sign of intoxication at the time of the accident.

Of that number, 39 patients, or 78%, were found definitively to have cardiac irregularities. Twenty-percent of the patients were diagnosed with supraventricular tachycardia (SVT), which is rapid heartbeats in the heart's upper chambers. Another 20% were diagnosed with vasovagal syncope, which is a fainting spell caused by a malfunction of the nerves that control the action of the heart and blood vessels. Advanced AV block was found in 13% of the patients. AV block is degeneration of the normal electrical conduction system that predisposes to very slow heart rates. Both vasovagal syncope and SVT were found in 6% of the patients.

Of the 22% of the original group of patients who did not have a diagnosis after further testing, vasovagal syncope was strongly suspected in 9%. The remaining patients were suspected to have sick sinus syndrome, in which the heart's sinus node fails to perform its role as the heart's natural pacemaker; SVT; and ischemia, which is decreased blood supply to the heart.

Schoenfeld uses two diagnostic tools: the tilt table test and an electrophysiology study. In the tilt table test patients lie on a table that can be moved to a nearly upright position while symptoms, heart rate and blood pressure are continuously monitored. An electrophysiology study measures the heart's electrical function, allowing doctors to locate abnormal sites inside the heart that may be causing serious abnormal heart rhythms, or arrhythmias. Once the diagnosis is made, there are a variety of effective avenues for treatment.

"With appropriate pharmacologic, surgical or device-based therapy, there was no recurrent driving-related impaired consciousness events at follow up," Schoenfeld said.

He attributes the increase in these cases to the population's longevity and mobility as well as to heightened awareness about fainting episodes that have gone undiagnosed.

"The driving episode may have brought it to their attention," Schoenfeld said. "Still, people often attend to the trauma related to the accident, but they forget to look at the fainting spell that caused the accident."

-- By Jacqueline Weaver

T H I SW E E K ' SS T O R I E S

Yale celebrates 299th Commencement

Fellowship winners to pursue summer study across the globe

Yale helps the new 'Amistad' set sail on its educational mission

Festival Time: Celebrations of art, music and culture at Yale, city sites

Environmental leaders to join school's faculty

Conservation leaders named McCluskey Fellows

Alumni return to campus to celebrate reunions

Researcher links unexplained car accidents and heart irregularities

Center's family celebration will mark Cancer Survivors Day

Family Festival to celebrate Yale Art Gallery exhibitions

Students will teach in China, Hong Kong

Movie theaters 'pitch in' to raise funds for Yale pediatric programs

Edmund Gordon is honored for his achievements

'Feminist humor maven' will speak at campaign school

Symposium will pay tribute to Dr. Marvin Sears

Fair will highlight continuing education

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