1. Department of Cardiology, Christchurch Hospital , 2 Riccarton Avenue, PO Bag 4710, Christchurch 8140 , New Zealand
2. Department of Cardiology, The Prince Charles Hospital , Brisbane , Australia
3. Department of Caridac Rhythm Services, Monash Medical Centre , Melbourne , Australia
4. Department of Cardiac Rhythm Managment, Medtronic Inc. , Mounds View, MN , USA
5. Department of Cardiology, The Austin Hospital , Melbourne , Australia