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Myocardial perfusion defects and associated systemic ventricular dysfunction in congenitally corrected transposition
T S Hornung1, E J Bernard, E T Jaeggi
1Adolph Basser Cardiac Institute, Royal Alexandra Hospital for Children, Sydney, Australia.
Insights
Patients with congenitally corrected transposition of the great arteries (TGA) often experience myocardial ischemia and infarction, leading to impaired ventricular function and reduced exercise capacity. These findings suggest a significant role for ischemia and infarction in TGA-related ventricular failure.
Area of Science:
- Cardiology
- Pediatric Cardiology
- Cardiac Imaging
Background:
- Systemic right ventricular morphology increases risk of contractile dysfunction.
- The underlying causes of this dysfunction in congenitally corrected transposition of the great arteries (TGA) remain unclear.
Observation:
- This study investigated myocardial perfusion and function in unoperated patients with uncomplicated congenitally corrected TGA.
- Five patients (aged 3.5–34 years) underwent maximal exercise stress testing and sestamibi scanning.
Findings:
- Reduced exercise performance was observed in older patients.
- Sestamibi scans revealed reversible ischemia in 4 patients and infarction in 5.
- Impaired ventricular ejection fraction (<55%) was noted in most patients, correlating with perfusion defects.
Implications:
- Unoperated congenitally corrected TGA is associated with high rates of myocardial perfusion defects.
- Ischemia and infarction are likely key contributors to ventricular dysfunction and failure in this population.
- These findings highlight the importance of assessing myocardial health in managing TGA.
Background:
Patients with systemic ventricles of right ventricular morphology are at high risk of contractile dysfunction, the cause of which has not been fully elucidated.
Objective:
To assess whether ischaemia or infarction contributes to ventricular impairment in unoperated patients with uncomplicated congenitally corrected transposition of the great arteries (TGA) by studying myocardial perfusion and function.
Setting:
Paediatric and adult congenital cardiac clinics of a tertiary referral centre.
Patients:
Five patients with congenitally corrected TGA but without associated structural cardiac defects (aged 3.5 to 34 years).
Interventions:
Maximal exercise stress testing using standard or modified Bruce protocols. Sestamibi (technetium-99m methoxy isobutyl isonitrile) scanning after isotope injection at maximal exercise and rest.
Main Outcome Measures:
Maximum exercise capacity; right ventricular myocardial perfusion, regional wall motion, and thickening; right ventricular ejection fraction.
Results:
The two youngest patients (3.5 and 11 years) had normal exercise capacity for age, while the others had reduced exercise performance. Sestamibi scanning showed reversible myocardial ischaemia in four patients and fixed defects indicating infarction in five. Irreversible defects were mostly associated with impaired wall motion and thickening. The ejection fraction was normal (65%) in the youngest patient but < 55% in the others (mean (SD) 47(11)%).
Conclusions:
Patients with unoperated congenitally corrected TGA have a high prevalence of myocardial perfusion defects, with consequent abnormalities of regional wall motion and thickening, and impaired ventricular contractility. These data suggest that ischaemia and infarction are important in the pathogenesis of ventricular failure in this condition.