use
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/soap/eutils.wsdl
to check pubmed data

ex:
Feasibility of simplifying balloon mitral valvuloplasty by obviating left-sided cardiac catheterization using on-line guidance with transesophageal echocardiography.
PMID: 12796174

1. use run_eSearch
db=pubmed
term=Feasibility+of+simplifying+balloon+mitral+valvuloplasty
field=titl
you'll get PMID: 12796174
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=pubmed&term=Feasibility+of+simplifying+balloon+mitral+valvuloplasty&field=titl

2.use run_eSummary
db=pubmedid=12796174
you'll get:
Feasibility of simplifying balloon mitral valvuloplasty by obviating left-sided cardiac catheterization using on-line guidance with transesophageal echocardiography.
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/esummary.fcgi?db=pubmed&id=12796174&retmode=xml