Conventional analysis techniques require small samples of the work for testing, further damaging the book. But analyzing the gases coming off of the old books is noninvasive.
A thorough history is fundamental to the diagnosis of cardiovascular disease and cannot be replaced by routine or random noninvasive and invasive testing which is expensive and inefficient.
The use of both noninvasive and invasive preoperative testing should be limited to those circumstances in which the results of such tests will clearly affect patient management.