Derek - I had similar but somewhat less severe problems a year ago and after various cardiologists mulled over medication changes, the expert and head honcho took one look at my record and said I needed a defibrillator/pacemaker.
This was done - superby - at Sheffield Northern General Hospital almost a year ago. Now I have no arrthythmia problems (touch wood) and it is simply getting the right dose of beta blockers, as I have recently experienced what my GP called a "hitting the buffers" situation. But I feel much better and am beginning to lead a fairly normal, if still restricted life.

So don't lose hope!