Alexander Vorobyev Nov 22, 2011:

It can't be alone There should be something before "ПН". Please provide it.
Probably it's a description of right ventricle - ПЖ (with a typo in your source).

Michael Moskowitz (asker) Nov 22, 2011:

Correction: I did miss a little bit there. It clearly states:
ПН=-. Дополнительная хорда в области верхушки.

Like the "ПН" is one thing and "Дополнительная хорда в области верхушки." is another

Alexander Vorobyev Nov 22, 2011:

Скан Очень хочется увидеть скан оригинала.