s-a node造句

• The s-a node is often called the pacemaker of the heart because it establishes the basic rhythm at which the heart beats .
  S-A结由于建立了心跳的基本节律，故常称为起搏点。
• The s - a node is often called the pacemaker of the heart because it establishes the basic rhythm at which the heart beats
  S - a结由于建立了心跳的基本节律，故常称为起搏点。