Hemodynamic and Echocardiographic Effects of Temporary Biventricular Pacing Immediately Post Cardiopulmonary Bypass for Patients with Chronic Heart Failure Undergoing Open-Heart Surgery.
J.D. Muehlschlegel MD, E.B. Lobato, MD, C
Klodell MD and Y.G. Peng MD
Department of Anesthesiology, University of Florida, Gainesville, Florida
Background: Chronic biventricular (BV) pacing is known to improve left
ventricular (LV) function in patients with low ejection fraction during
resynchronization therapy. Temporary atrio-ventricular pacing is frequently
required after cardiopulmonary bypass, in patients with systolic dysfunction
undergoing CABG. Therefore, we aimed to analyze the acute effects of
biventricular pacing versus single ventricle pacing on hemodynamics, and
left ventricular function immediately after cardiopulmonary bypass.
Methods: Eight patients with decreased left ventricular function (mean
ejection fraction 35 ± 5 %) underwent CABG under cardiopulmonary bypass (CPB).
Pulmonary artery catheters and transesophageal echocardiography were used in
all subjects. Temporary pacing electrodes were placed on the right atrium
and the apex of the right & lateral wall of the left ventricle prior to
separation from CPB. After weaning from CPB and hemodynamic stabilization,
the hemodynamic effects of three atrio-ventricular pacing modes were studied
for 4 minutes each. The pacing modes differed in the site of ventricular
stimulation and were 1) right ventricular, 2) left ventricular and 3)
bi-ventricular. The sequence of the pacing modes was randomly assigned.
Hemodynamic and echocardiographic data were collected and recorded during
each pacing mode. The study ended following the last pacing mode
measurement. Statistical analysis was performed with analysis of variance.
Results: Biventricular pacing increased cardiac output by 9%, 9%, and 15%
over right ventricular pacing, left ventricular pacing, and pre-bypass
values, respectively (p=0.055). The fractional area of change increased
significantly with biventricular pacing compared to pre bypass (41% to 49%,
P<0.05) as well as compared to RV (41%) and LV pacing (LV 39%). A tendency
for improved diastolic function during biventricular pacing was suggested by
an increased propagation velocity of 52 cm/s compared to 39 cm/s and 40 cm/s
for right and left ventricular pacing, respectively (p=0.06).
Conclusion: Biventricular pacing, immediately after cardiopulmonary bypass,
improves left ventricular systolic function and may improve diastolic
function in patients with a poor ejection fraction. In patients with
depressed left ventricular function, biventricular pacing is a viable option
to improve left ventricular systolic function.
