Altered right ventricular papillary muscle position and orientation in patients with a dilated left ventricle

To investigate the impact of left ventricular dilatation on right ventricular papillary muscle displacement.

Thirteen patients underwent high-resolution cardiac magnetic resonance imaging at Emory University Hospital: Seven patients with congestive heart failure and a dilated left ventricle composed the dilated left ventricular group, and 6 normal subjects were used as a control. A total of 120 cardiac magnetic resonance imaging slices were acquired in a short-axis view at end diastole for each subject. Cardiac magnetic resonance imaging slices were used to identify the papillary muscle tip position in 3-dimensional coordinates for the septal, posterior, and anterior papillary muscles. The centroid of the papillary muscle coordinates was used as the reference point for comparison between subjects. The relative orientation between the right ventricular papillary muscles was evaluated and compared between the dilated left ventricular group and normal subjects.

Dilatation of the left ventricle resulted in a significant (P = .05) displacement of the septal right ventricular papillary muscle toward the centroid: normal group, 0.0285 ± 0.036 mm/mm versus dilated left ventricular group, 0.1437 ± 0.026 mm/mm. More specifically, the septal papillary muscle significantly (P = .03) moved away from the septal wall (normal group: 0.61 ± 0.09 mm/mm, dilated left ventricular group: 0.379 ± 0.037 mm/mm). Specific locations of all 3 right ventricular papillary muscles were reported for normal subjects and patients with a dilated left ventricle.

Patients with a dilated left ventricle have significantly increased displacement of the septal right ventricular papillary muscle away from the septum when compared with normal controls. This demonstrates pathophysiologic contribution of the left ventricle to specific papillary muscle alterations within the right ventricle.