Intact chordae tendineae increase ventricular volume measurement error by the balloon method.

We assessed the accuracy of the intraventricular balloon method of left ventricular volume measurement with all chordae tendineae intact and then severed. The space between the endocardium and the balloon is the source of the volume measurement error. We assessed the volume errors at different intra-balloon pressures between 50 and 250 mmHg, using formalin fixed canine left ventricles. The volume error with all chordae tendineae intact was significantly greater than with all chordae tendineae severed at any balloon pressure. The difference of the volume errors under these two conditions amounted to 1.9-3.3 ml regardless of intra-balloon pressures. We visually confirmed that this difference predominantly originated from the space behind the tense chordae tendineae.