No such thing as a Heartbeat Network

rajeshmokashi17 as the title of this article explains, there is 'no such thing as a heartbeat network' - but assuming that you are referring to a Cluster Network which has been enabled for Cluster Communications, if this is the only Cluster Network with Cluster Communications enabled and it fails on one node, the other node would attempt to failover any resources which are dependent on that network and bring them online.  If that cluster network fails on both nodes, the cluster will not be able to function so the cluster service will stop on both nodes and will continuously try to restart until the nodes are able to reach each other and reform the cluster.  Ideally you should have redundancy for all networks and NICs to avoid any single points of failure, in which case a single failed network should not have any significant impact as long as the redundant networks/devices remain connected.