1342483 - Anatomical influences of the Damus-Kaye-Stansel anastomosis on coronary perfusion in patients with hypoplastic left heart syndrome

Hypoplastic left heart syndrome (HLHS) is a complex cardiac underdevelopment of the left sided part of the heart resulting in a very small left ventricle causing hemodynamic insufficiency. Patients suffering from this condition are treated with a staged surgery (Norwood I or Hybrid, PCPC or Comprehensive Stage II, TCPC). The right ventricle serves as the systemic ventricle and the pulmonary trunc is used as the neo-aorta. The native aorta is connected to the neo-aorta by creating the Damus-Kaye-Stansel (DKS) anastomosis. Despite the success of this staged approach, patients are limited in their performance throughout their lives and are at high risk of hemodynamic failure. Therefore, our work addresses various conceivable anatomic aspects of the DKS anastomosis that may influence the coronary blood supply. Coronary blood flow depends solely on retrograde flow in the native aorta (this means blood flows not through the aortic valve, it is about retrograde flow in the sense of through the DKS anastomosis back into the native aorta), when antegrade flow through the hypoplastic left ventricle and aortic valve is not present as is the case with most HLHS patients.



Methods: We retrospectively analyzed 31 HLHS patients with a median age of 9.7 years (range 0.25 to 17.1 years) who had CMR testing in a routine follow-up. We obtained flow measurements of the native aorta and the neo-aorta in free breathing using a 1.5 Tesla MR scanner. We evaluated the impact of age, heart rate, cross-sectional area of the smallest part of the neo-aorta and the native aorta, length of the neo-aorta from the valve to the DKS anastomosis, as well as the obtuse angle between the native aorta and the neo-aorta. We correlated retrograde blood flow through the native aorta with the aformentioned parameters. None of the patients had antegrade flow in the native aorta so that blood flow in the native aorta represents the full coronary blood supply.


Results:

Blood flow in the native aorta was very small compared to the flow in the neo-aorta. Median blood flow in the native aorta was 2.7% (range 0.6 to 10 %) of the flow in the neo-aorta (cardiac output). There is a marked positive correlation (R²=0.252) between heart rate and blood flow in the native aorta. The angle in the DKS anastomosis between the neo-aorta and the native aorta had no impact on blood flow in the native aorta. The median angle of was 141 degrees (range 114 to 177 degrees). Furthermore, we found no correlation between the cross-sectional area of the native aorta at the level of the DKS anastomosis and the blood flow in the native aorta. The cross-sectional area of the neo-aorta at the level of the DKS anastomosis correlated with blood flow in the native aorta (median 4.95mm², range 1.36 to 11.52mm², R²=0.2797).



Conclusion:

Heart rate and the cross-sectional area of the neo-aorta positively affect coronary blood supply in patients with hypoplastic left heart syndrome and may improve myocardial performance.