Serial measurements of exercise performance in pediatric heart transplant patients using stress echocardiography
Joanne P Yeung1, Derek G Human, George G S Sandor
1Department of Pediatrics, BC Children's Hospital, The University of British Columbia, Vancouver, BC, Canada.
Insights
Pediatric heart transplant recipients (HTP) can exercise safely, but show reduced exercise tolerance and diminished cardiac function compared to healthy controls. Their hemodynamics and left ventricular function remain stable post-transplant.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Physiology
- Transplantation Medicine
Background:
- Heart transplantation is a viable treatment for pediatric end-stage congenital heart disease.
- Evaluating functional outcomes post-transplant is crucial with medical advancements.
Purpose of the Study:
- To assess exercise capacity and hemodynamics in pediatric heart transplant recipients (HTP).
- To compare exercise performance of HTP with healthy controls (CON).
Main Methods:
- Serial exercise testing using stress echocardiography in 7 pediatric HTP.
- Measurements included echocardiography-Doppler, heart rate (HR), and blood pressure during staged exercise.
- Comparison with 12 healthy CON.
Main Results:
- HTP performed significantly less work (940 vs. 1218 J/kg) and had lower peak exercise stroke volume index (SVI), cardiac index (CI), and HR.
- HTP exhibited reduced systolic function (SF) and an abnormal relationship between myocardial contractility and pressure load.
- Hemodynamics and left ventricular function remained stable during follow-up in HTP.
Conclusions:
- Pediatric heart transplant recipients can exercise safely.
- Exercise tolerance is reduced, with diminished hemodynamics and contractility.
- Long-term follow-up shows stable hemodynamics and left ventricular function.
Abstract:
Heart transplantation is an increasingly acceptable therapeutic option for children with end-stage and complex congenital heart disease. With advances in surgery, immunosuppression, and follow-up care, functional outcomes need to be evaluated. We report the results of serial exercise testing performed using stress echocardiography in a cohort of pediatric HTP. HTP (n = 7) exercised on a semi-recumbent ergometer to volitional fatigue. Echocardiography-Doppler measurements, HR, and blood pressure were taken at rest and during staged exercise. Results were compared with healthy CON (n = 12). HTP did significantly less work during exercise (940 vs. 1218 J/kg, p < 0.03). Their SVI (33 vs. 49 mL/m(2), p < 0.003), CI (5.16 vs. 9.25 L/min/m(2), p < 0.0005), and HR (162 vs. 185 bpm, p < 0.02) were lower at peak exercise. HTP had a lower SF at peak exercise (48% vs. 52%, p < 0.03) and an abnormal relationship between the MVCFc and σPS. During follow-up, hemodynamics and left ventricular function remained relatively constant in HTP. HTP are able to exercise safely; however, their exercise tolerance is reduced, and hemodynamics and contractility are diminished. Over time, their hemodynamics and left ventricular function have remained relatively constant.
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