Exercise stress CMR reveals reduced aortic distensibility and impaired right-ventricular adaptation to exercise in patients with repaired tetralogy of Fallot

Figures

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  Fig 1. Diagram illustrating the progression of the cardiac imaging protocol. Goal was to obtain twice the resting heart rate (Note the right Y axis representing an example of one volunteer). Each vertical line represents an apnea.Cine for cardiac function lasting 3 min, carried out across three breath holds of about 12s. Each cine represents the average of 5 heartbeats, 4 slices are acquired in one breath hold. ‘Loc’: Localizer sequence. After exercise this was done only if necessary.

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  Fig 2. Change in ventricular parameters between stress and rest. Δ = exercise volume value minus rest volume value. EDV = end diastolic volume. ESV = end systolic volume. Sv = stroke volume. *: p = 0.028. ns = non-significant p-value. All DATA are indexed to BSA. There was a significant difference in right ventricular stroke volume, because patients do not adapt their ventricular muscle to exercise. Even if there was no other statistical difference we observed a tendency to lower biventricular contractility in patients.

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  Fig 3. Change in cardiac output during exercise and at rest. Δ = exercise percentage value minus rest percentage value. LVCO = left ventricular cardiac output. RVCO = right ventricular cardiac output. ns = nonsignificant p-value. This figure shows that there was no difference between the groups in terms of adaptability of the flow during exercise; the plots on the right side show that the RVCO tends to increase less in the RTOF.

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  Fig 4. Change between exercise and rest for ejection fraction. Δ = exercise percentage value minus rest percentage value. LVEF = left ventricular ejection fraction. RVEF = right ventricular ejection fraction. *: p = 0.039. **: p = 0.014. This figure shows that patients do not adapt their ventricular function to exercise.

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  Fig 5. Comparison between patients and volunteers for aortic distensibility at rest and exercising. AD = aortic distensibility. AAo = ascending aorta. DAo = descending aorta. *: p = 0.027. ns = non-significant p-value. This result shows a statistical difference between the patients and volunteers on AAo when exercising which does not exist at rest. This suggests that exercise can reveal a decrease in aortic distensibility at an early stage.

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  Fig 6. Correlation curve showing rate pressure pulse and parameters for repaired tetralogy of Fallot. LV and RV = left and right ventricles. CO = cardiac output. i = index. RPP = rate pressure pulse. AC = aortic compliance. AD = aortic distensibility. AAo = ascending aorta. DAO = descending aorta. All measurements are indexed. In RTOF at rest and on exertion a significant correlation was found between cardiac work and both biventricular cardiac output. This correlation is less stronger than these of volunteers. This clearly demonstrate a lack of adaptation of AD AAo with RPP.

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  Fig 7. Curve showing rate pressure pulse correlation and parameters for volunteers. LV and RV = left and right ventricles. CO = cardiac output. i = index. RPP = rate pressure pulse. AC = aortic compliance. AD = aortic distensibility. AAo = ascending aorta. DAO = descending aorta. All measures are indexed. In volunteers at rest and on exertion a strong and significant correlation was found between cardiac work and both biventricular cardiac output; cardiac work and all the stiffness parameters.