Sunday, October 10, 2004 - 2:26 PM

Reversal of Cardiopulmonary Failure by Mandibular Distraction

RA Maercks, MD, XP Reyna Rodriguez, DDS, JJ Marler, MD, Cathy Ebert, MS, LE Landa, MD, DMD, Enrique Ochoa Lopez Diaz, MD, and CB Gordon, MD.

Reversal of Cardiopulmonary Failure by Mandibular Distraction PURPOSE: To demonstrate the improvement in multiple cardiopulmonary functions after mandibular distraction.

MATERIALS AND METHODS: Thirty-three patients with symptomatic micrognathia underwent mandibular distraction using the “No Vector” Technique.  Preoperative and postoperative echocardiograms (1, 3 and 12 months) were performed and several parameters were evaluated, including: right and left ventricular (RV, LV) dimensions, LV mass index, LV geometry, pulmonary artery pressure (PAP) and total pulmonary vascular resistance (TPVR) as calculated using standard methods.  At each interval, the echocardiogram was used to calculate: LV mass (0.891.04[IVS+PWT+LVED]3-[LVED]3)+0.06); LV geometry (Normal, Concentric remodeling, Eccentric hypertrophy, Concentric hypertrophy); RV structure; PA pressure (Velocity/ Baseline frequency x2xcos0); and Pressure gradient (4 x maximal flow velocity2).

RESULTS: Preoperatively, both LV indices were increased when compared to age matched controls (P < .001).  Those patients with severe OSAS had pathologic increases in both RV dimension and LV mass indices (P < .001).  There was a change in LV geometry in over half of the patients preoperatively and these changes were severe enough to be associated with an increased risk of cardiac events in later life(P < .001).  PA pressures were also calculated to be elevated in more than half of patients preoperatively and normalized postoperatively.  Total PVR was also normalized after surgery. 

Postoperative echocardiogram revealed normalization of RV and LV dimensions, with a significant decrease in both LV thickness and LV mass index.   These parameters were compared using repeated measures analysis (MANOVA), and post-hoc testing was performed using standard methods.

CONCLUSION: Pathologic cardiopulmonary changes that are seen in patients with severe micrognathia and obstructive sleep apnea include increases in ventricular thickness, PA pressures, and PVR.  These changes may have significant implications for future cardiac disease.  Mandibular distraction can improve or normalize many of these changes, supporting early intervention for airway as a means to minimize later cardiac risk factors.  These data merit futher evaluation in a larger series to evaluate more subtle degrees of obstruction and establish criteria for functional intervention.