Now that half of the shared veins have been separated, Carl's circulatory system is carrying more of its own load.
Similarly, he said, if doctors tried to tie off all the twins' shared veins at once, the result could be a disaster.
Before, most of the boys' shared veins emptied into Clarence's body, and the extra load on his circulatory system gave him high blood pressure.
Tomorrow, Carl and Clarence Aguirre, 22-month-old Filipino twins who are joined at the head, are scheduled to undergo their third operation to tease apart the network of shared veins in their heads.
The purpose of the operation was to begin the delicate process of tying off shared veins and gradually diverting blood flow so that each boy has his own network of blood vessels to carry blood away from the brain.
So when spurred by word of mouth to join the stampede to see the movie "My Big Fat Greek Wedding," I found -- except for the ending foretold in the title -- I shared a vein of experiences with the main character, the daughter of immigrants, played by the screenplay's author, Nia Vardalos.
The sharing of veins has led to the formation of a "lake" of blood between the two boys' brains, he said.
He said the need for separate stages did not become apparent until the surgery was already under way, and doctors encountered unforeseen obstacles in rerouting blood flow in the heads of the sisters, who shared a major vein that drained blood from the brain.
Despite the countless high-tech brain images they had produced, the surgeons were caught unaware by a major vein the women shared.
In a similar vein, the share of highly educated individuals in our sample of non-migrants is found to be much higher than the one observed in the general population.
But they share major veins that drain blood from the brain, and dividing those vessels will be risky and delicate, a procedure best conducted a step at a time in several operations, their doctors say.
