[GNC] Accounts and HSAs question

[Mark]

Hello,

I've recently started using GnuCash and, with the help of the tutorial, 
gotten most things figured out.  The issue that I'm wrestling with now 
relates to HSAs (health savings accounts). Please consider the following:

1.  I incur a medical charge of $100, and put it on my Visa card. (debit 
expense:medical:mark and credit liability:creditcard:visa)
2.  I pay my Visa card from my checking account. (debit 
liability:creditcard:visa and credit asset:bank:checking)
3.  My HSA disburses $100 and I deposit it to my checking account. 
(debit asset:bank:checking and credit bank:hsa)

The above seems okay to me at first glance.  However, how do I know what 
bills the HSA has disbursed funds for, and what bills are still waiting? 
I'm sure there is a logical way of connecting things, but I cannot wrap 
my head around it.  A search of the archives thru 2013 only had one 
mention of HSA and it was related to the income side.

I would appreciate any suggestions, particularly before my head 
explodes.  :-)

Thank you.
Mark