I am trying to read an excel spreadsheet via open xml sdk with the following format and determine which 1st row merged cells corrpsond to the 2nd row.

How can I check if a cell is in a merged state?

```
------------------------------------------------------------
       Main Heading 1     |     Main heading 2              |
------------------------------------------------------------
Sub Head 1   | sub head 2 |     sub head 3                  |
-------------------------------------------------------------
             |            |                                 |

```