Objectives: We set to measure the interatrial pressure gradient during simulated obstructive sleep apnea (OSA).
Background: OSA occurs when a sleeping patient attempts to inhale against an obstructed airway. How this event affects the interatrial pressure gradient has not been defined. We hypothesized that simulated OSA in a conscious subject (Mueller maneuver [MM], inspiration against obstruction) would promote increased right-to-left pressure gradient, and then the substrate for right-to-left atrial shunting.
Methods: Selected patients underwent simultaneous measurement of airway and atrial pressures (both left and right atrium [LA, RA]) using high-fidelity micromanometry at rest, during MM, and during VM, during right heart catheterization.
Results: Ten patients (age 55±11 years, two women) were successfully studied. During the onset of MM, RA pressure transiently but consistently exceeded LA pressure in response to the steep decline in intrathoracic pressure (maximum RA-LA pressure gradient increased from 0.1±1.4 mm Hg at baseline to 7.0±4.3 mm Hg during MM, P<0.001). The maximum right-to-left atrial pressure gradient during Mueller maneuver was higher than that achieved during the Valsalva maneuver release (P<0.007).
Conclusions: The onset of MM increased right-to-left pressure gradient across the atrial septum, likely as a result of greater blood return to the RA from extrathoracic veins. The RA-LA pressure gradient achieved during MM was greater than that observed during VM. These findings delineate the hemodynamic substrate for right to left shunting during OSA.
- Foramen ovale
- Mueller maneuver
- Sleep apnea
- Valsalva maneuver
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Cardiology and Cardiovascular Medicine