Background: Exercise echocardiography in combination with cardiopulmonary exercise testing (CPET)
allows for evaluation of cardiac function evaluated using echocardiography during
physical exertion while at the same time measuring cardiopulmonary function. As heart
rate can only be increased to maximal levels during true physical exercise this is
the only method to evaluate cardiac function during maximal exercise while at the
same time allowing for objectifying the extent of physical exertion. So far, exercise
echocardiography is mainly limited to adults tall enough to fit on a tilt-recline
ergometer.
Method: We evaluated 6 children (3 girls and 3 boys) after arterial switch operation or Kawasaki
disease, below the required height for tilt-recline ergometers, for exercise echocardiography
in combination with CPET on a treadmill. We used an adapted Bruce treadmill protocol.
All Echocardiography assessments were undertaken with the child standing upright,
bent slightly forward. The evaluations were undertaken before CPET, after the 4th
and the 8th step, and directly as well as after 2 and 3 minutes after ending the exercise.
The treadmill was stopped for echocardiography for 30 seconds.
Results: All children were able to perform the exercise tests up to maximal exertion. The
CPET results are presented in the following table. Exercise echocardiography allowed
for good image quality even for evaluating global longitudinal strain. Five children
presented with normal cardiac function even at peak exercise. One child showed reduced
cardiac function which worsened over the course of the CPET. A catheter investigation
revealed stenosis of the right coronary artery.
|
Parameter
|
Mean ± standard deviation
|
|
(mL/kg/min)
|
48.0 ± 4.9
|
|
Peak RER
|
1.3 ± 0.1
|
|
Peak heart rate (beats/minute)
|
195 ± 8.6
|
|
Exercise time (min)
|
15.3 ± 1.8
|
|
Peak O2 pulse (mL/min)
|
6.7 ± 1.0
|
Conclusion: Exercise echocardiography in combination with cardiopulmonary exercise testing in
children too small for being able to perform on a tilt-recline ergometer is feasible
and safe. Image quality during upright echocardiography is very high and allows for
the estimation of global longitudinal strain. This is a first study showing the possible
inclusion of exercise echocardiography for evaluating coronary insufficiency in children
during exertion.
