Maximal hemodynamic response after the Fontan procedure: Doppler evaluation during the treadmill test
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Published on: February 9, 2016
R G Cortes1, G Satomi, M Yoshigi
1Department of Pediatric Cardiology, Heart Institute of Japan, Tokyo Women's Medical College, Japan.
Insights
Children after the Fontan procedure show reduced exercise capacity. Their stroke index and cardiac index responses to exercise are impaired compared to healthy peers.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Physiology
Background:
- The Fontan procedure is a palliative surgery for complex congenital heart disease.
- Assessing exercise capacity is crucial for monitoring Fontan-associated physiology.
Purpose of the Study:
- To evaluate the hemodynamic response to maximal exercise in young patients post-Fontan procedure.
- To compare exercise performance and cardiac function between Fontan survivors and healthy children.
Main Methods:
- 16 young patients who underwent the Fontan procedure performed a maximal treadmill test (Bruce protocol).
- Continuous-wave Doppler echocardiography measured peak aortic blood flow velocity, stroke index, and cardiac index at rest and during exercise.
- Hemodynamic data were compared to 18 age-matched healthy children.
Main Results:
- Fontan patients had a 37% shorter endurance time than controls.
- Stroke index increase was blunted in Fontan patients during submaximal exercise and decreased at maximal exercise.
- Cardiac index response was comparable initially but failed to ascend in Fontan patients at maximal exercise.
- Hemodynamic values, including cardiac index increase (79% vs. 170%), were significantly lower in the Fontan group at maximal exercise.
Conclusions:
- Fontan survivors exhibit subnormal stroke volume response during exercise.
- Impaired cardiac index response and reduced endurance highlight functional limitations post-Fontan procedure.
- These hemodynamic findings are critical for understanding exercise intolerance in Fontan patients.
Abstract:
After undergoing the Fontan procedure for congenital heart disease, 16 young patients performed a maximal treadmill test according to the Bruce protocol. The peak velocity of the blood flow in the ascending aorta, stroke index, and cardiac index were measured by continuous-wave Doppler echocardiography at rest and at each stage of the test. The results were compared with those from 18 normal children. The body surface area was similar in the two groups. The endurance time was 37% shorter in the Fontan group than in the control group. From the beginning of exercise until the sixth minute, the increase in stroke index was lower in the Fontan group (NS). After that point, the stroke index was maintained at a high level in the control group but decreased toward its original level in the Fontan group. The response of cardiac index to exercise in the two groups was comparable until the sixth minute, after which the Fontan group failed to maintain an ascending curve. All the hemodynamic values were significantly higher in the control group at maximal exercise; at this point the cardiac index had increased 79% in the Fontan group and 170% in the control group. The subnormal response of the stroke volume at submaximal exercise and the subsequent decrease at maximal exercise following the Fontan procedure are important hemodynamic findings.
