Assessment of right ventricular function during supine bicycle exercise after Mustard's operation

Area of Science:

• Pediatric Cardiology
• Cardiac Physiology
• Congenital Heart Disease

Background:

• The Mustard operation is a palliative procedure for d-transposition of the great arteries (d-TGA).
• Long-term RV function after the Mustard operation is not fully understood, especially under physiological stress.

Purpose of the Study:

• To evaluate right ventricular (RV) performance during supine bicycle exercise in children with d-TGA after Mustard's operation.
• To identify potential abnormalities in RV function under stress in this patient population.

Main Methods:

• Gated equilibrium nuclear angiography was used to assess RV performance.
• Nineteen clinically well children (mean age 6.4 years) post-Mustard operation were studied at rest and peak exercise.
• Ejection fraction and end-diastolic volumes were compared between rest and exercise.

Main Results:

• Resting RV ejection fraction averaged 44%, with no significant change at peak exercise.
• Eleven out of 19 children demonstrated an abnormal RV ejection fraction response (no increase or decrease) during exercise.
• Reduced end-diastolic volumes were observed in patients with abnormal RV function under stress.

Conclusions:

• Clinically stable children following the Mustard procedure for d-TGA can exhibit impaired RV function during exercise.
• These findings raise concerns about the RV's capacity to act as the systemic ventricle long-term.
• Further monitoring of RV function in these patients is warranted.