Our heart’s left ventricle empties on each
heartbeat. In many people with diabetes, it takes
longer for the heart to refill with blood between
heartbeats than in healthy individuals. But exercise
can fix the problem, a new study shows.
About half of everyone who has type 2 diabetes also
has diastolic dysfunction, which can eventually
develop into heart failure.
Diastolic dysfunction means that the heart’s ability
to relax and fill with blood between heartbeats is
impaired. The heart is then less able to pump enough
blood into the body with each beat, and needs to
work harder even though the pumping function itself
is still intact.
“Impaired diastolic heart function can be reversed,
and our findings focus on the effect of exercise to
prevent cardiovascular disease in this group of
patients,” says Siri Marte Hollekim-Strand, who is a
PhD candidate at NTNU and first author of the
recently published study.
By Kjetil Lenes - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3705964
As the left ventricle contracts and sends blood into
the body, it makes a twisting motion, akin to what
happens when you wring out a washcloth. The new
study shows that when the heart chamber refills in
between heartbeats– called the untwist – that rate
is slower in patients with Type 2 diabetes and
diastolic dysfunction than in healthy individuals.
“Energy is stored when the heart twists. This energy
gets used during the untwisting and allows the blood
to be drawn into the heart in the first part of the
phase between two heartbeats, called the diastole.
The untwist rate is an excitation heart ultrasound
measurement that probably has great significance for
the early diastolic heart phase,” says physician and
researcher Charlotte Björk Ingul at the Department
of Circulation and Medical Imaging at NTNU. Ingul is
the study’s last author.
“Our pilot study suggests that exercise can
normalize some cardiac function impairments in this
patient group,” adds Hollekim-Strand.
The researchers examined the twist of the left
ventricle using echocardiography, also called an
echo test or heart ultrasound. It turned out that
most twist rate measurements at rest were similar
for the study’s diabetic patients and the 37 healthy
control subjects with approximately the same age,
gender and BMI as the diabetes group. The exception
was the “time to peak untwist rate” measurement.
“Before the training the untwist was significantly
delayed in diabetic patients, but after three months
of training this measurement was also the same as in
the control subjects without diabetes,” says
Hollekim-Strand.
The 37 diabetes patients, who were randomly
distributed between two training groups, trained for
12 weeks. One group trained at home at moderate
intensity for half an hour every day, according to
current recommendations of the Norwegian Directorate
of Health. The second group did intensive 4 × 4
interval training on the treadmill three times a
week throughout the study period. The untwist rate
of both training groups improved equally.
“Untwist rate may become an important marker of
diastolic heart function in the future, but that
will require 3D ultrasound with high resolution for
better measurement methods than we have today. Right
now we have to combine many different ultrasound
measurements for diastolic heart function to confirm
that function is impaired,” says Ingul.
For more information
Hollekim-Strand, S. M., Høydahl, S. F., Follestad,
T., Dalen, H., Bjørgaas, M. R., Wisløff, U., & Ingul,
C. B. (2016).
Exercise Training Normalizes Timing of Left
Ventricular Untwist Rate, but Not Peak Untwist Rate,
in Individuals with Type 2 Diabetes and Diastolic
Dysfunction: A Pilot Study
Journal of the American Society of Echocardiography,
3 March 2016 (online)
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