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Possible sources of right-to-left shunting in patients following a total cavopulmonary connection
G Buheitel1, M Hofbeck, U Tenbrink
1Department of Pediatric Cardiology, University Erlangen-Nürnberg, Germany.
Insights
Children undergoing total cavopulmonary connection often experience reduced arterial oxygen saturation due to right-to-left shunting. This study identified intrapulmonary and intracardiac shunts as key contributors to this phenomenon.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Surgery
- Physiology
Background:
- Total cavopulmonary connection (TCPC) is a palliative surgical procedure for complex congenital heart disease.
- Post-TCPC patients frequently exhibit mildly decreased arterial oxygen saturation.
- Understanding the mechanisms of right-to-left shunting is crucial for improving outcomes.
Purpose of the Study:
- To investigate the underlying mechanisms of right-to-left shunting in pediatric patients after total cavopulmonary connection.
- To quantify intrapulmonary and intracardiac shunts in this population.
Main Methods:
- Elective cardiac catheterization was performed in 19 children 3.6 years post-TCPC.
- Intrapulmonary, intracardiac, and total right-to-left shunts were calculated.
- Mechanical ventilation with 100% oxygen was utilized during measurements.
Main Results:
- Intrapulmonary right-to-left shunt averaged 10.8% of pulmonary blood flow.
- Total right-to-left shunt was 18.9% of systemic blood flow.
- Intracardiac shunt was higher (13.0%) in patients with venovenous collaterals or baffle leaks compared to those without (6.4%).
Conclusions:
- Intrapulmonary shunting is likely due to ventilation-perfusion mismatch, not arteriovenous fistulas.
- Intracardiac shunting results from baffle leaks, systemic-pulmonary venous collaterals, and coronary sinus drainage.
- These shunts contribute to persistent hypoxemia after total cavopulmonary connection.
Abstract:
Despite a good haemodynamic result, many children have a mildly decreased arterial-oxygen saturation following a total cavopulmonary connection. Our study was performed to determine possible mechanisms of right-to-left shunting in these patients. We performed elective cardiac catheterization in 19 children at a mean interval of 3.6 years following a total cavopulmonary connection. The intrapulmonary right-to-left shunt, the intracardiac right-to-left shunt and the total right-to-left shunt were calculated under mechanical ventilation with 100% oxygen. The intrapulmonary right-to-left shunt was 10.8+/-3.5% of the pulmonary blood flow, and the total right-to-left shunt accounted for 18.9+/-5.2% of the systemic blood flow. The intracardiac right-to-left shunt in patients with no relevant venovenous collaterals or leaks in the atrial tunnel was calculated at 6.4+/-3.0% of the systemic blood flow, while the intracardiac right-to-left shunt in patients with relevant collaterals or leaks accounted for 13.0+/-5.9% of the systemic blood flow. Since intrapulmonary arteriovenous fistulas were not demonstrated angiographically in any of our patients, the intrapulmonary right-to-left shunt is probably due to low ratios of perfusion to ventilation in some pulmonary segments. The intracardiac right-to-left shunt was due to leaks across the interatrial baffle, collaterals between systemic and pulmonary veins, and to the coronary sinus draining to the pulmonary venous atrium.