Question category: Cardiology
A 67 year old male presents to his GP with a cold right hand. He has had a previous coronary artery bypass graft 3 years ago. Over the last few months he has noticed his hand being cold and painful. It occurs at rest and is not worsened by any particular movements. On examination his capillary refill time is slowed to about 3 seconds. The hand is cold and the radial pulse is impalpable. The rest of the examination is normal. He has not had an angina attack for some time. What is the most likely cause?