To determine the threshold at which rapid atrial pacing brings on fetal @entity1457 , we made a fetal @entity4710 model and measured the central venous pressure, aortic pressure, and right and left ventricular outputs in five fetal @entity742 . Under maternal anesthesia, the uterus was opened, and under local anesthesia, @entity9031 catheters were inserted into the fetal superior vena cava and ascending aorta through a neck incision. Pacing leads (Medtronic model 6492) were then sutured onto the fetal right @entity955 via right thoracotomy. Ventricular output was estimated using a Toshiba SSH-65A echocardiography by a transuterine approach. Fetal hemodynamics were observed without pacing (control), and at the atrial pacing rates of 200, 300, 350, and 400/min. Central venous pressure (CVP) increased and the aortic pressure decreased when the right atrium was paced at 350/min or more. Right ventricular output decreased when the right atrium was paced at 300/min or more. The left ventricular output, however, remained constant. The right ventricular output was 382 +/- 106 mL/kg/min at control, and 391 +/- 117 mL/kg/min when paced at 200/min, but decreased to 210 +/- 138 mL/kg/min when paced at 300/min, to 223 +/- 102 mL/kg/min when paced at 350/min, and to 186 +/- 86 mL/kg/min when paced at 400/min. Fetal @entity1457 occurred when the right atrium was paced at 300/min or more.

Hemodynamic effect of rapid atrial pacing in fetal XXXX .

@entity742 :: ('9940', 'Species') :: ['lambs'] @entity1457 :: ('MESH:D012769', 'Disease') :: ['circulatory failure'] @entity955 :: ('MESH:D001281', 'Disease') :: ['atrial appendage'] @entity4710 :: ('MESH:D013617', 'Disease') :: ['supraventricular tachyarrhythmia'] @entity9031 :: ('MESH:D011145', 'Chemical') :: ['polyvinyl']
@entity742 :: (9940,Species) :: ['lambs']
