Interpretaion of ergospirometry in Interpretaion of ergospirometry in congenital heartcongenital heart

Prof. Dr. T. ReybrouckProf. Dr. T. Reybrouck

Departments of Pediatric Cardiology Departments of Pediatric Cardiology and Cardiovascular Rehabilitation and Cardiovascular Rehabilitation Gasthuisberg University HospitalGasthuisberg University Hospital

3000 Leuven, Belgium3000 Leuven, Belgium

Exercise testing in children with congenital heart disease (CHD)

• Exercise testing in adult cardiac patients is focused mainly on ischemic heart disease

• Exercise ECG is helpful in diagnosing the presence or absence of ischemic heart disease

Exercise testing in children with CH (cont’d )

• In children with heart diseases, the type of pathology is different

• The majority of children will present with congenital heart disease. Ischemic heart disease is very rare

Usefulness of exercise testing with gas exchange measurents

• Exercise testing is much more sensitive in assessing exercise performance than history taking or questionnaires on physical activity

• Functional capacity can objectively be assessed by exercise testing with gas exchange measurements (ergospirometry)

• Exercise tests are preferentially performed on a treadmill (advantageous for young children) or on cycle ergometer (for older children and adolescents)

Integration of oxygen transport system

Wasserman et al,1994

Breath-by-breath measurements of gas exchange

Nowadays gas exchange is measured on a breath-by-breath basis with computerised systems

Beaver et al, 1983

Measurement of gas exchange • Gas exchange can also be measured by a

mixing box, but this device does not allow to study gas exchange kinetics.

Wilmore et al, 1974

Devices and analysers

Wasserman et al, 2004

Conventional parameters to assess functional capacity

• Maximal oxygen uptake (VO2 max, or VO2 peak)

• Ventilatory anaerobic threshold

• Ventilatory efficiency: VE/VO2, VE/VCO2 (VD/VT can be estimated from PETCO2)

Typical example

Comparison parameters gas exchange vs heart rate response

Reybrouck et al, Ped Cardiol, 1986

Application of ergospirometry in Pediatric Cardiology

Follow up gegevens Eur J Ped

Reybrouck et al, Eur J Ped 1995

New concepts in ergospirometry

• Slope of VO2 vs exercise intensisty

• Slope VCO2 vs VO2

• Slope VE vs VCO2

Slope VO2 vs exercise intensity

Eyskens et al, 2000

Slope VCO2 vs VO2

Reybrouck et al, J Appl 1996

Exercise intensity (VO2)

Ven

tila

tion

(l/

min

)

Wasserman et al, 1999

Physiological dead space ventilation

Efficiency of gas exchange

Since children with CHD can exercise well at moderate levels of exercise but develop exercise intolerance at higher levels of exercise we studied the difference between alveolar and total ventilation, which represents the dead space ventilation.

Total ventilation, alveolar ventilation and dead space ventilation in CHD

5

15

25

35

45

inclination of treadmill

To

tal

- A

lveo

lar

VE

(l/m

in)

FontanNL

TFTGA

Ventilatory efficiency in TGA

Conclusions• Ergospirometry is a useful tool to assess

functional capacity, since it gives objective information about the exercise tolerance of the patients.

• New concepts such as slope of VO2 vs exercise intensity or VCO2 vs VO2 give information about the cardiorespiratory exercise function and mechanisms of exercise intolerance