When a premature atrial contraction consistently comes after each normal cardiac cycle, it's called atrial bigeminy and when one consistently comes after every two normal cardiac cycles, it's called atrial trigeminy.

当一个房性期前收缩总是紧接着每一个正常心动周期而来时，它被称为二联律；当一个房性期前收缩总是紧接着每两个正常心动周期而来时，它被称为三联律。