The heart is myogenic that is it is auto regulated by specialised muscles (nodal tissue).
The cardiac acivity is regulated by the following:

i. A special neural centre in the medulla oblangata can moderate the cardiac function through autonomic nervous system (ANS).
ii. Neural signals through the sympathetic nerves (part of ANS) can increase the rate of heart beat, the strength of ventricular contraction and thereby the cardiac output. 

iii. The parasympathetic neural signals decrease the rate of heart beat, speed of conduction of action potential and thereby the cardiac output.
 
iv. Adrenal medullary hormones can also increase the cardiac output.