Sir,
I read with interest the case report entitled, “Hemodynamic rounds: Dilemma in the management of disconnected pulmonary arteries with double arterial ducts” by Sivakumar and Mohakud,[1] where the authors have pointed out the difficulties in the decision-making in cases with differential pulmonary arterial pressures in the two lungs due to isolation of one pulmonary artery. The authors did balloon occlusion of the right lung (being supplied by the large ductus) and asserted that the clinical decision was made with the available data in response to the balloon occlusion and taking into account other factors.
It is true that large data are not available to guide decision in such settings; however, a simple consideration that generally holds true is that if the pressures and resistance in one lung are normal, connecting the two pulmonary arteries is possible irrespective of the resistance in the other high pressured lung (right lung in this case). This is based on the assumption that the mean resistance (R) will always be lower than the lower of the two values R1 and R2, representing the resistances in two parallel circuits. Mathematically, the mean resistance (R) will always be lower than the lower of the R1 or R2, since 1/R = 1/R1 + 1/R2. We have previously presented a validation of this concept with more severe resistance in one lung wherein, after the connection of two pulmonary arteries, the resultant pressures were lower and clinically acceptable.[2] The large experience with single lung transplant in patients with severe pulmonary hypertension also supports such an approach.[3] Therefore, I would suggest that it may be a reasonable approach to connect the two pulmonary arteries, if feasible, irrespective of the resistance in the other lung in this case as the gradient across the patent ductus was high enough, suggesting a nearly normal vascular resistance in the left lung.
The authors need to be congratulated for documenting this case in view of rarity of documented similar data that support connecting the two pulmonary arteries if the size and vascular resistance in one lung are normal.
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Conflicts of interest
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REFERENCES
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