The ECG tracing and the electromicroscopy of the muscle biopsy belong to a patient who has problem with droopy eyelids.

a. What does the ECG show?

Complete heart block. The tracing shows that no P wave is conducted to the ventricle.

b. What does the electromicroscopy show?

The mitochondria contain elaborate crystal within the cristae. This appearance is seen in mitochondrial myopathies.

c. What is the most likely diagnosis?

Kearn-Sayre's syndrome. 
It is a type of chronic progressive external ophthalmoplegia which has a mitochrondrial inheritance. Complete heart block is the main cause of death and pacemaker is often needed.

d. What other ocular signs may be present?

Most patients present before 20 year old age with pigmentary retinopathy, bilateral ptosis and ophthalmoplegia. 

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