How can the heart pump enough blood to siamese twins as it has a further way to go? Do they have a stronger heart or

Question: How can the heart pump enough blood to siamese twins as it has a further way to go? Do they have a stronger heart or even two hearts?
- Keywords:
  blood,
  heart,
  siamese twin,
  twin
Asked by molineux to Adam, Joanna, Louise S, Louise W, Marcus on 14 Nov 2012.
- Adam Paige answered on 14 Nov 2012:
  
  Our hearts are good at working harder or less hard depending on the circumstances. When we are ill, exercising or frightened they pump harder. So the heart in siamese twins should be able to pump harder to cope.
  
  I am not an expert about this, however, I believe that most siamese twins actually have two hearts. It depends where abouts they are joined. They may have separate blood streams entirely.
- Louise Walkin answered on 14 Nov 2012:
  
  Do you mean in the womb or out of the womb? In the womb, the heat of the fetus doesn’t have to do much, it’s the mother’s heart that normally works harder to supply blood to her own body and the fetus. After they have been born, they may have two hearts in which case, there shouldn’t be a problem. If the babies are sharing their cirulatory system, things become difficult when wanting to seprate them. The heart would need to go to the one that the heart seem more “at home” in, and then the other baby would need a transplant. I’m not sure if the heart would be bigger than normal sized baby heart, but I should imagine it would have to work harder as it is pumping the blood around two bodies.
- Joanna Giles answered on 14 Nov 2012:
  
  As the other guys have already said, Siamese twins are rare and can sometimes have two hearts.
  The heart is an organ that has really strong muscles and on average can pump up to 5 litres of blood in one minute! It has to be strong so that it can reach down to the toes and back again.
  
  However, Siamese twins usually have to be separated these days to ensure survival. If they share a heart, normally it is too much strain on the heart to pump the blood around two bodies and they would have to be separated. Although each Siamese twin couple is unique and doctors have to make difficult decisions on separation depending on exactly how the twins are joined.