TY - JOUR
T1 - Mueller maneuver attenuates left atrial phasic volumes and myocardial strain in healthy younger adults
AU - Wright, Stephen P.
AU - Dawkins, Tony G.
AU - Harper, Megan I.
AU - Stembridge, Mike
AU - Shave, Rob
AU - Eves, Neil D.
N1 - Publisher Copyright:
© 2023 the American Physiological Society.
PY - 2023/10/18
Y1 - 2023/10/18
N2 - The left atrium (LA) is a key, but incompletely understood, modulator of left ventricular (LV) filling. Inspiratory negative intrathoracic pressure swings alter cardiac loading conditions, which may impact LA function. We studied acute effects of static inspiratory efforts on LA chamber function, LA myocardial strain, and LV diastolic filling. We included healthy adults (10 males/9 females, 24 ± 4 yr) and used Mueller maneuvers to reduce intrathoracic pressure to ̶30 cmH2O for 15 s. Over six repeated trials, we used echocardiography to acquire LA- and LV-focused two-dimensional (2-D) images, and mitral Doppler inflow and annular tissue velocity spectra. Images were analyzed for LA and LV chamber volumes, tissue relaxation velocities, transmitral filling velocities, and speckle tracking-derived LA longitudinal strain. Repeated measures were made at baseline, early Mueller, late Mueller, then early release, and late release. In the late Mueller compared with baseline, LV stroke volume decreased by ̶10 ± 4 mL (P < 0.05) and then returned to baseline upon release; this occurred with a ̶11 ± 9 mL (P < 0.05) end-diastolic volume reduction. Early diastolic LV filling was attenuated, reflected by decreased tissue relaxation velocity (̶2 ± 2 cm/s, P < 0.05), E-wave filling velocity (̶13 ± 14 cm/s, P < 0.05), and LA passive emptying volume (̶5 ± 5 mL, P < 0.05), each returning to baseline with release. LA maximal volume decreased (̶5 ± 5 mL, P < 0.05) during the Mueller maneuver, but increased relative to baseline following release (þ 4 ± 5 mL, P < 0.05), whereas LA peak positive longitudinal strain decreased (̶6 ± 6%, P < 0.05) and then returned to baseline. Attenuated LA and in turn, LV filling may contribute to acute stroke volume reductions experienced during forceful inspiratory efforts. NEW & NOTEWORTHY In healthy younger adults, the Mueller maneuver transiently reduces left atrial filling and passive emptying during the reservoir and conduit phases, respectively. Corresponding reductions are seen in left atrial reservoir and conduit phase longitudinal myocardial strain and strain rate. However, left atrial pump phase active function and mechanics are largely preserved compared with baseline. Rapid changes in LA chamber volumes and myocardial strain with recurrent forceful inspiratory efforts and relaxation may reflect acute LA stress.
AB - The left atrium (LA) is a key, but incompletely understood, modulator of left ventricular (LV) filling. Inspiratory negative intrathoracic pressure swings alter cardiac loading conditions, which may impact LA function. We studied acute effects of static inspiratory efforts on LA chamber function, LA myocardial strain, and LV diastolic filling. We included healthy adults (10 males/9 females, 24 ± 4 yr) and used Mueller maneuvers to reduce intrathoracic pressure to ̶30 cmH2O for 15 s. Over six repeated trials, we used echocardiography to acquire LA- and LV-focused two-dimensional (2-D) images, and mitral Doppler inflow and annular tissue velocity spectra. Images were analyzed for LA and LV chamber volumes, tissue relaxation velocities, transmitral filling velocities, and speckle tracking-derived LA longitudinal strain. Repeated measures were made at baseline, early Mueller, late Mueller, then early release, and late release. In the late Mueller compared with baseline, LV stroke volume decreased by ̶10 ± 4 mL (P < 0.05) and then returned to baseline upon release; this occurred with a ̶11 ± 9 mL (P < 0.05) end-diastolic volume reduction. Early diastolic LV filling was attenuated, reflected by decreased tissue relaxation velocity (̶2 ± 2 cm/s, P < 0.05), E-wave filling velocity (̶13 ± 14 cm/s, P < 0.05), and LA passive emptying volume (̶5 ± 5 mL, P < 0.05), each returning to baseline with release. LA maximal volume decreased (̶5 ± 5 mL, P < 0.05) during the Mueller maneuver, but increased relative to baseline following release (þ 4 ± 5 mL, P < 0.05), whereas LA peak positive longitudinal strain decreased (̶6 ± 6%, P < 0.05) and then returned to baseline. Attenuated LA and in turn, LV filling may contribute to acute stroke volume reductions experienced during forceful inspiratory efforts. NEW & NOTEWORTHY In healthy younger adults, the Mueller maneuver transiently reduces left atrial filling and passive emptying during the reservoir and conduit phases, respectively. Corresponding reductions are seen in left atrial reservoir and conduit phase longitudinal myocardial strain and strain rate. However, left atrial pump phase active function and mechanics are largely preserved compared with baseline. Rapid changes in LA chamber volumes and myocardial strain with recurrent forceful inspiratory efforts and relaxation may reflect acute LA stress.
KW - chamber function
KW - echocardiography
KW - intrathoracic pressure
KW - left atrium
KW - myocardial mechanics
UR - http://www.scopus.com/inward/record.url?scp=85174751702&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.00505.2023
DO - 10.1152/ajpheart.00505.2023
M3 - Article
C2 - 37737735
AN - SCOPUS:85174751702
SN - 0363-6135
VL - 325
SP - H1235-H1241
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 5
ER -