diff --git a/IPython/zmq/kernelmanager.py b/IPython/zmq/kernelmanager.py
index f82fc87..f04fb04 100644
--- a/IPython/zmq/kernelmanager.py
+++ b/IPython/zmq/kernelmanager.py
@@ -515,10 +515,13 @@ class HBSocketChannel(ZmqSocketChannel):
     time_to_dead = 3.0
     socket = None
     poller = None
+    _running = None
+    _pause = None
 
     def __init__(self, context, session, address):
         super(HBSocketChannel, self).__init__(context, session, address)
         self._running = False
+        self._pause = False
 
     def _create_socket(self):
         self.socket = self.context.socket(zmq.REQ)
@@ -538,51 +541,69 @@ class HBSocketChannel(ZmqSocketChannel):
         # after the sockets are connected.
         time.sleep(2.0)
         while self._running:
-            since_last_heartbeat = 0.0
-            request_time = time.time()
-            try:
-                #io.rprint('Ping from HB channel') # dbg
-                self.socket.send_json('ping')
-            except zmq.ZMQError, e:
-                #io.rprint('*** HB Error:', e) # dbg
-                if e.errno == zmq.EFSM:
-                    #io.rprint('sleep...', self.time_to_dead) # dbg
-                    time.sleep(self.time_to_dead)
-                    self._create_socket()
-                else:
-                    raise
+            if self._pause:
+                time.sleep(self.time_to_dead)
             else:
-                while True:
-                    try:
-                        self.socket.recv_json(zmq.NOBLOCK)
-                    except zmq.ZMQError, e:
-                        #io.rprint('*** HB Error 2:', e) # dbg
-                        if e.errno == zmq.EAGAIN:
-                            before_poll = time.time()
-                            until_dead = self.time_to_dead - (before_poll -
-                                                              request_time)
-
-                            # When the return value of poll() is an empty list,
-                            # that is when things have gone wrong (zeromq bug).
-                            # As long as it is not an empty list, poll is
-                            # working correctly even if it returns quickly.
-                            # Note: poll timeout is in milliseconds.
-                            self.poller.poll(1000*until_dead)
+                since_last_heartbeat = 0.0
+                request_time = time.time()
+                try:
+                    #io.rprint('Ping from HB channel') # dbg
+                    self.socket.send_json('ping')
+                except zmq.ZMQError, e:
+                    #io.rprint('*** HB Error:', e) # dbg
+                    if e.errno == zmq.EFSM:
+                        #io.rprint('sleep...', self.time_to_dead) # dbg
+                        time.sleep(self.time_to_dead)
+                        self._create_socket()
+                    else:
+                        raise
+                else:
+                    while True:
+                        try:
+                            self.socket.recv_json(zmq.NOBLOCK)
+                        except zmq.ZMQError, e:
+                            #io.rprint('*** HB Error 2:', e) # dbg
+                            if e.errno == zmq.EAGAIN:
+                                before_poll = time.time()
+                                until_dead = self.time_to_dead - (before_poll -
+                                                                  request_time)
+
+                                # When the return value of poll() is an empty list,
+                                # that is when things have gone wrong (zeromq bug).
+                                # As long as it is not an empty list, poll is
+                                # working correctly even if it returns quickly.
+                                # Note: poll timeout is in milliseconds.
+                                self.poller.poll(1000*until_dead)
                             
-                            since_last_heartbeat = time.time() - request_time
-                            if since_last_heartbeat > self.time_to_dead:
-                                self.call_handlers(since_last_heartbeat)
-                                break
+                                since_last_heartbeat = time.time() - request_time
+                                if since_last_heartbeat > self.time_to_dead:
+                                    self.call_handlers(since_last_heartbeat)
+                                    break
+                            else:
+                                # FIXME: We should probably log this instead.
+                                raise
                         else:
-                            # FIXME: We should probably log this instead.
-                            raise
-                    else:
-                        until_dead = self.time_to_dead - (time.time() -
-                                                          request_time)
-                        if until_dead > 0.0:
-                            #io.rprint('sleep...', self.time_to_dead) # dbg
-                            time.sleep(until_dead)
-                        break
+                            until_dead = self.time_to_dead - (time.time() -
+                                                              request_time)
+                            if until_dead > 0.0:
+                                #io.rprint('sleep...', self.time_to_dead) # dbg
+                                time.sleep(until_dead)
+                            break
+
+    def pause(self):
+        """Pause the heartbeat."""
+        self._pause = True
+
+    def unpause(self):
+        """Unpause the heartbeat."""
+        self._pause = False
+
+    def is_beating(self):
+        """Is the heartbeat running and not paused."""
+        if self.is_alive() and not self._pause:
+            return True
+        else:
+            return False
 
     def stop(self):
         self._running = False
@@ -646,8 +667,8 @@ class KernelManager(HasTraits):
     # Channel management methods:
     #--------------------------------------------------------------------------
 
-    def start_channels(self, xreq=True, sub=True, rep=True, hb=True):
-        """Starts the channels for this kernel.
+    def start_channels(self, xreq=True, sub=True, rep=True):
+        """Starts the channels for this kernel, but not the heartbeat.
 
         This will create the channels if they do not exist and then start
         them. If port numbers of 0 are being used (random ports) then you
@@ -660,8 +681,6 @@ class KernelManager(HasTraits):
             self.sub_channel.start()
         if rep:
             self.rep_channel.start()
-        if hb:
-            self.hb_channel.start()
 
     def stop_channels(self):
         """Stops all the running channels for this kernel.
@@ -672,16 +691,13 @@ class KernelManager(HasTraits):
             self.sub_channel.stop()
         if self.rep_channel.is_alive():
             self.rep_channel.stop()
-        if self.hb_channel.is_alive():
-            self.hb_channel.stop()
 
     @property
     def channels_running(self):
         """Are any of the channels created and running?"""
         return self.xreq_channel.is_alive() \
             or self.sub_channel.is_alive() \
-            or self.rep_channel.is_alive() \
-            or self.hb_channel.is_alive()
+            or self.rep_channel.is_alive()
 
     #--------------------------------------------------------------------------
     # Kernel process management methods: