ST. LOUIS -- A cardiologist at Saint Louis University School of Medicine was the first to identify a new hereditary condition that increases the risk of sudden cardiac death. The risk factor - a dramatic, short interval in the heart's electrical impulses - was originally diagnosed in a Collinsville, Ill., family.
Three members of the family - mother, daughter and son - are subsequently undergoing surgery to implant defibrillators to lessen the risk of sudden cardiac death due to erratic electrical heart function. The surgery for Mary Hill, the mother in the family, will take place at Saint Louis University Hospital next Monday, Sept. 29.
"I'm just glad this was discovered before anything more happened in our family," says Mrs. Hill, who has suffered a few bouts of rapid, irregular heartbeat and whose father developed atrial fibrillation in his later years. "It's odd that we're the first family in the whole world to be diagnosed with this condition, but we're glad it was identified and that it's treatable."
The condition is related to the duration of electrical activity during each heartbeat, called the QT interval, which can be measured in a standard electrocardiogram (ECG). "It's been well-known for many years that a prolonged QT interval can lead to sudden cardiac death," says cardiologist Preben Bjerregaard, MD, professor of internal medicine at Saint Louis University School of Medicine and Director of the Electrophysiology and Pacemaker Service at Saint Louis University Hospital. "But we've found that a persistent short QT interval may be just as deadly."
In 2000, Dr. Bjerregaard first published his findings about the Collinsville, Ill., family in Cardiology, a Swiss medical journal. And at the meeting of the American College of Cardiology earlier this year, he heard from colleagues in Germany and Italy who noted similar short QT intervals in two different families. In one of those families, six people had died suddenly.
"I knew then that we were dealing with something even more serious than noted in any previous medical literature and that we had probably found a new hereditary risk factor for sudden cardiac death," Dr. Bjerregaard says.
"A long QT interval is often the culprit behind the sensational cases of athletes dying from sudden cardiac death who may have exhibited no prior symptoms," says Dr. Bjerregaard. "We've known for years that a long QT interval is a hereditary condition and is dangerous, but the short QT interval also appears to be hereditary and often exhibits no symptoms as well. Physicians and patients should be alert to this potentially life-threatening condition and begin to look for both the long and short QT interval abnormality in any electrocardiogram."
Every time the heart contracts, it emits an electrical impulse. Electrocardiograms, or ECGs, can track impulse wave patterns and determine the length of time between the impulses. Electrical impulses within the ventricles of the heart are designated by the letters "QT." A QT interval can indicate how effectively the heart is contracting in its lower chambers and how much blood is moving throughout the body. Patients with irregular QT intervals may experience abnormally fast heart rhythms. If the heart cannot return to a normal rhythm, the patient may develop ventricular fibrillation, a life-threatening irregular heartbeat that can cause sudden cardiac death.
In the Illinois family, the daughter, Shalon Gardner, suddenly developed a very rapid heartbeat when she was 17 years old while undergoing surgery for persistent gallstones in 1999. She was diagnosed with atrial fibrillation (in the upper chambers of her heart) and physicians had to subsequently "shock" her heart back into a regular rhythm.
"She thought she was going to die," said her mother, Mary Hill. "She recovered from her surgery and we were referred to Dr. Bjerregaard at Saint Louis University Hospital for immediate follow-up."
Dr. Bjerregaard found that Gardner's QT interval was extremely short and she sometimes complained of rapid heartbeats. "I was concerned that she would develop an erratic heartbeat in the lower chambers of her heart, which might lead to sudden cardiac death," says Dr. Bjerregaard.
When Gardner's mother and brother came along for a clinic visit, Dr. Bjerregaard asked if he could check their ECGs. To his surprise, both had an extremely short QT interval, leading him to surmise that the short QT interval was an inherited condition much like the long QT interval. A check of Gardner's father later showed no similarity.
Shalon Gardner, now 22 years old and married, underwent surgery to implant a defibrillator on August 8. Her brother, Travis Hill, 25, who was diagnosed with the shortest QT interval in the family, had his defibrillator implanted on Aug. 13. Mary Hill, 55, a teacher at St. Peters and Paul School in Collinsville, Ill., delayed her surgery until Sept. 29 so that she could get the school year started for her second-graders.
"This is an electrical phenomenon of the heart and it's a treatable condition," Dr. Bjerregaard says. "Once diagnosed, defibrillators can be implanted to stabilize erratic rhythms, but it first has to be diagnosed."
"I'm just glad this was discovered before anything more happened in our family," said Mary Hill, who has suffered a few bouts of rapid, irregular heartbeat and whose father developed atrial fibrillation in his later years. "It's odd that we're the first family in the whole world to be diagnosed with this condition, but we're glad it was identified and that it's treatable."
Materials provided by Saint Louis University. Note: Content may be edited for style and length.
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