WordPress at a glance
action is not described

heartbeat_tick action-hook . WP 3.6.0

Fires when Heartbeat ticks in logged-in environments.

Allows the transport to be easily replaced with long-polling.

Usage

add_action( 'heartbeat_tick', 'action_function_name_2911', 10, 2 );
function action_function_name_2911( $response, $screen_id ){
	// action...
}
$response(array)
The Heartbeat response.
$screen_id(string)
The screen id.

Where the hook is called

wp_ajax_heartbeat()
wp-admin/includes/ajax-actions.php 2843
do_action( 'heartbeat_tick', $response, $screen_id );

Where the hook is used (in WP core)

Does not used.