Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:If a thrombus was detected, the patient was not a candidate for PMV. Transthoracic echocardiogram measurement of MVA and quantification of MR were repeated the day after PMV.
PMV was performed by a percutaneous transseptal anterograde approach and either the Babi c double-balloon technique (n ¼ 44 patients) or the Inoue balloon technique (n ¼ 488 patients), with conventional hemodynamic parameters monitored as previously described.14 Cardiac output (CO) was measured using the Fick or the thermodilution technique, and MVA was calculated using the Gorlin formula.
Category: