Cytotoxic shock is a medical condition that is caused by abnormally high levels of cytotoxin in a humanoid's body. Some of the symptoms leading up to this condition include a rapid and irregular pulse rate.
B'Elanna Torres went into cytoplasmic shock after her autonomic functions were overtaken by a cytoplasmic lifeform. The Doctor was able to stabilize the condition by administering two milligrams of inaprovaline. (VOY: "Nothing Human")