Session PB6.5

Stroke Volume during Mueller Maneuver Measured by Impedance Cardiography in Patients with Mitral Regurgitation

I Viscor*, P Jurak, V Vondra, J Halamek, P Leinveber

Institute of Scientific Instruments
Brno, Czech Repub.

The Mueller maneuver (MM) is frequently used to simulate obstructive sleep apnea. During the Mueller maneuver, the fall in intrathoracic pressure results in the instant fall in stroke volume. The fall is more stressed in patients with congestive heart failure. The quick changes in stroke volume during the Mueller maneuver can be detected non-invasively by echocardiography, arterial pulse-wave analysis and electrical impedance cardiography (ICG). We use our bioimpedance monitor device (ISI BM1.2) to test ability of ICG method for detection of stroke volume change during the Mueller maneuver. Fifteen patients with mitral regurgitation performed ten MMs, 10 seconds each maneuver. During MM the subjects maintain the intrathoracic pressure of –30 cm H2O. The impedance signal was recorded and analyzed off-line . Baseline data was evaluated 10 seconds directly preceding MM. Maneuver data was evaluated during the last 7, 5 seconds of MM. Release data was evaluated during 10 seconds interval after 2, 5 second transient interval. The heart rate stays almost unchanged during MM. The stroke volume was evaluated according to Sramek equation from the maximal gradients of thorax impedance during systole. Rapid stroke volume changes during MM in most subjects is evident and the change was consistent during all maneuvers. However the value and direction was inconsistent among subjects. It ranging between –37% to +35% of the baseline stroke volume. These results suggest the impact of mitral regurgitation on the reliability of the ICG method.

(Abstract Control Number: 182)