Atrial
Fibrillation Can Be A Family Affair
Study Finds Genetic
Underpinnings
Having a parent with
atrial fibrillation (AF) strongly increases an offspring’s
risk of developing this heart rhythm disorder, according to
a report from the National Heart, Lung, and Blood
Institute (NHLBI) Framingham Heart
Study.
In the latest study,
published in the Journal of the American Medical Association,
researchers found the risk doubled for offspring with at least
one parent with AF compared to offspring whose parents did not
have the condition.
Atrial fibrillation
is the most common heart rhythm disorder in the US, affecting
more than 2 million adults. The prevalence of the condition
is rising and scientists predict that about 5.6 million people
will have the disorder by 2050.
Known causes of AF
include abnormalities in the heart’s structure and long-term
uncontrolled high blood pressure.
Atrial
Fibrillation Increases in Offspring
The study of 2,243
adults is the first to find a genetic connection for AF in a
community sample, the study authors say.
“This important
research finding will need to be confirmed but it opens up a
new avenue of research on atrial fibrillation," says Dr. Barbara
Alving, acting director of the NHLBI.
"Now scientists can
start looking at genetic factors that might contribute to AF -
searching for the genes involved in this increasingly common
disorder,” she says.
The study’s
findings strongly support the notion that AF has genetic underpinnings.
Most cases of AF occur in older people.
The disorder affects
about 1 in every 10 persons aged 80 and over. In the new study,
the risk of AF tripled when both parents and the offspring were
under age 75. The risk also tripled when the analysis was limited
to offspring who had no clinically apparent heart disease.
“Disorders with
a genetic component often occur at a younger age or in the absence
of major diseases like heart disease that trigger the condition,”
said the study’s lead investigator Dr. Caroline Fox of
the Framingham Heart Study.
According to the NHLBI,
AF occurs when electrical signals in the heart's upper chambers
(the atria) are fired in a very fast, uncontrolled manner. Electrical
signals then arrive in the heart's lower chambers (the ventricles)
in an erratic pattern, creating an irregular heartbeat and affecting
the heart’s ability to pump blood.
Atrial fibrillation
can produce symptoms including palpitations, an unexplained,
rapid heartbeat, lightheadedness, or occasionally chest pain.
It can also be asymptomatic.
AF can lead to complications
such as stroke and congestive heart failure. Treatment with
medications, surgery, or devices, is designed to slow the heart
rate and restore normal rhythm when possible, and to prevent
stroke.
Blood-thinning medications
(anticoagulants) are an important means of preventing stroke
in AF patients.
The Framingham Offspring
study of AF involved 1165 women and 1078 men whose parents were
members of the “original” Framingham Heart Study.
The offspring were
at least 30 years of age and free of atrial fibrillation at
the first exam. Offspring and original study participants had
routine clinic exams, including physical examinations, interviews,
lab tests, and electrocardiograms.
AF in both offspring
and original “parental” participants was confirmed
by an electrocardiogram. Parental cases occurred from 1949 to
2002 and offspring AF cases occurred from 1983 to 2002.
When the Framingham
researchers analyzed the data, they found that 30 percent of
participants had at least one parent with AF. Seventy offspring
(23 women) developed AF during the study at a mean age of 62
years.
When stated in terms
of 1,000 persons per year, the results indicate that the number
of offspring developing AF would be 4.5 if a parent had AF and
3 if parents did not have AF.
Findings
Suggest Further Study Needed
Dr. Fox cautions that
the Framingham findings should not alarm people who have a parent
with AF.
“AF with or
without a family history is a common condition in the elderly,"
she says. "Our findings indicate to the scientific community
that we need more research on the genetic mechanisms of AF and
how they interact with environmental influences."
Dr. Fox added that
Framingham scientists hope to conduct further research into
the genetic basis of AF.
Always consult your
physician for more information.
Arrhythmias
Diagnostic Testing Explained
The American
Heart Association describes the following methods used
to diagnose arrhythmias:
Electrocardiographic
techniques
An arrhythmia is considered documented if it can be recorded
on an electrocardiogram (ECG or EKG.) This is the standard clinical
tool for diagnosing arrhythmias. It records the relative timing
of atrial and ventricular electrical events. It can be used
to measure how long it takes for impulses to travel through
the atria, atrioventricular (AV) conduction system and ventricles.
Often, though — because of the fleeting nature of arrhythmias
— the ECG of someone who complains of symptoms that suggest
arrhythmia appears normal.
Holter monitor
Suspected arrhythmias sometimes may be documented by using a
small, portable ECG recorder, called a Holter monitor (or continuous
ambulatory electrocardiographic monitor). This can record 48
hours of continuous electrocardiographic signals. While an ECG
is sort of a 12-second "snapshot" of the heart's electrical
activity, the Holter monitor is more like a "movie." For suspected
arrhythmias that occur less than daily, a patient can wear an
event monitor. It has a continuously updated memory loop and
can allow the heart to be monitored by telephone.
Treadmill
testing
This is an option that may provoke arrhythmias and makes their
diagnosis (and thus their proper treatment) easier. A treadmill
test may be used for people whose suspected arrhythmias are
clearly exercise-related. It is important to know if exercise
makes an arrhythmia worse. To test this, you will walk on a
treadmill - or ride a stationary bicycle - while your
heart rate and rhythm are monitored.
Tilt table
studies
A tilt test may be advised for some people who have had
recurrent fainting spells (syncope). This test shows how your
heart rate and blood pressure respond to a change in position
from lying down to standing up.
Transtelephonic
monitor (or event recorder)
Sometimes arrhythmia symptoms happen infrequently,
or pass so quickly that you cannot get to a physician or
hospital. In these cases, a "transient event monitor" may be
used. These small recorders are sent home with a person for
a month or two. When you have symptoms, attach the recorder
with bracelets, finger clips, or patches under the arms. The
ECG will be recorded and stored. When it's convenient, you can
transmit the ECG by phone to the cardiologist to be analyzed.
Echocardiogram
Echocardiography works much like sound waves used to study solid
objects in the sea (sonar). You may only think of ultrasound
being used to monitor a baby's growth, but ultrasound waves
can also show the heart's size, structure, and motion. This
simple, painless test often provides valuable information about
a heart with an arrhythmia.
Esophageal
electrophysiologic procedure
In some situations, your cardiologist may advise doing an esophageal
electrophysiologic procedure. This is used to diagnose or treat
the type of tachycardia you have.
Electrophysiologic testing
This method has become extremely valuable for provoking known
but infrequent arrhythmias and for unmasking suspected arrhythmias.
This procedure is done using local anesthesia. The ability to
electrically stimulate the heart at programmed rates and induce
precisely timed premature beats lets a physician assess electrical
properties of the heart's conduction system.
Always consult your
physician for more information. |
August 2004
Atrial
Fibrillation Can Be A Family Affair
Atrial
Fibrillation Increases in Offspring
Findings
Suggest Further Study Needed
Arrhythmias
Diagnostic Testing Explained
Heart
Health Benefits From Antioxidant-Rich Foods
Online
Resources
Heart
Health Benefits From Antioxidant-Rich Foods
A variety of veggies,
fruits, and nuts battled it out recently for the top spot on
a new list of the 20 most antioxidant-rich foods, ranked by
nutrition scientists at the US Department of Agriculture
(USDA).
In the end, small
red beans won the day, narrowly beating out wild blueberries
as the food with the highest concentration of disease-fighting
compounds per serving.
Antioxidants fight
damage to cells from rogue molecules called "free radicals."
Experts believe this assault on cells may fuel killer diseases
such as heart disease and cancer, and even aging itself.
The new Top 20 list,
published in the Journal of Agricultural and Food Chemistry,
is a relative ranking of the capacity of foods to interfere
with or prevent oxidative processes and to scavenge free radicals,"
explains list co-creator Ronald L. Prior, a USDA nutritionist
and research chemist based in Little Rock, Ark.
Prior and his colleagues
used the most advanced technologies available to tabulate antioxidant
levels in more than 100 different types of fruits, vegetables,
berries, nuts, and spices.
The Top 20 list includes:
There's "still a lot
we haven't learned" about why some foods are richer in antioxidants
than others, Prior says.
"Even though the small
red bean came out on top berries are better understood," Prior
says.
"The components that
contribute a lot of the antioxidant activity are what are called
anthocyanins, the compounds that give many berries their dark
blue color," he says.
In fact, color may
be key to spotting foods that fight free radicals, says Roberta
Anding, an American Dietetic Association spokeswoman
and a nutritionist at Texas Children's Hospital in Houston.
"If you're looking
for the best places to get antioxidants, I will usually tell
folks to look at the colors of the rainbow," she says.
Anding explains, "You'll
find lutein with some of the yellow pigments found in corn;
orange can be the pigments from the carotenoid family that are
found in cantaloupe, butternut squash, and mango; red could
come from things like lycopene, found in tomatoes and watermelon.
And then the darker colors - the purples, blues, in berries,"
she says.
But Prior cautioned
that just because a food has proven to be antioxidant-rich in
the USDA's lab, that does not mean all those nutrients
will be successfully absorbed by the human digestive tract.
"As we learn more
and more, we're finding that, depending on the chemical makeup
of antioxidants in different foods, some of them aren't apparently
absorbed as well, or else they are metabolized in a form where
they are no longer antioxidants," he says.
Whether a food is
eaten fresh, frozen, processed, or cooked can also affect its
antioxidant potency, Prior says. Blueberries are best when eaten
fresh rather than cooked in a pie, for example. On the other
hand, research has shown that gentle cooking raises the antioxidant
power of tomatoes, he notes.
Although experts are
working hard on the project, ongoing efforts to come up with
daily dietary guidelines for antioxidant consumption will be
"a long process," Prior says.
For her part, Anding
said people should not focus on one particular food, but attempt
to consume daily servings of a variety of fruits, vegetables,
and other wholesome foods.
Looking over the USDA
list, Anding suggests creating what she called an antioxidant
"power salad."
Always consult your
physician for more information.
Online
Resources
(Our Organization
is not responsible for the content of Internet sites.)
American
Heart Association
Centers
for Disease Control and Prevention (CDC)
HealthierUS.Gov
National
Heart, Lung, and Blood Institute (NHLBI)
National
Institutes of Health (NIH)
National
Library of Medicine
US
Health and Human Services |
