Name six causes of complete heart block

1. Chronic degenerative changes (sclerosis or fibrosis) of the conduction system NOT related to MI - a common cause seen particularly in older patients
   
2. Digitalis intoxication
   
3. Lyme disease
4. Open heart surgery, particularly after aortic valve replacement
   
5. Bacterial endocarditis
   
6. MI

Source

Goldberger: Clinical Electrocardiography: A Simplified Approach, 7th ed.