Echocardiographic Assessment
We performed TEE after induction of anesthesia before sternotomy and any
canulation of the patient. All measurements were done with Philips Epic
7 echocardiography machines and X8-2T-TEE probes. Examinations were
performed by a board certified echocardiographer according to recent
recommendations for TEE examination.13, 14
Real-time three-dimensional full-volume datasets, including the entire
RV, were acquired from a mid-esophageal RV-focused four-chamber-view.
Four-beat acquisition during apnea was performed. The settings of the
ultrasound machine were adapted to a high temporal resolution. TomTec
4D-RV-Function-2.0 (TomTec Imaging Systems GmbH, Unterschleissheim,
Germany) was used for estimation of three-dimensional derived
RV-free-wall strain (3D-RV FWS) and RV ejection fraction (3D-RV EF).
This software is based on speckle-tracking technology and provides a
semi-automated quantification of RV size and
function.15, 16 Therefore, RV borders needs mandatory
adjustment by the operator after automatic extraction and tracking of
the right ventricle out of the full-volume data set.16Figure 1 shows the assessment of 3D-RV EF and 3D-RV FWS by TEE.
For the evaluation of tissue velocity of the tricuspid annulus (RV S´),
tricuspid annular systolic excursion (TAPSE), and RV fraction area
change (RV FAC) we used Philips QLAB 10.8 software. TAPSE was assessed
in the midesophageal RV-focused four-chamber-view by measuring the
displacement of the tricuspid annulus in anatomic M-mode. Anatomic
M-mode is an angle independent M-mode that allows the operator to
position the cursor freely on the two-dimensional image. Therefore, the
cursor was directed towards the RV apex. RV FAC was evaluated from
midesophageal RV-focused four-chamber view. The change of RV area in
relation to diastolic RV area was calculated and is shown in percent. RV
S´ was assessed from the midesophageal RV-focused four-chamber view
measuring the peak positive tissue velocity using pulsed wave
tissue-Doppler imaging during ejection period in an angle-independent
manner. Therefore, the cursor of the Doppler was directed towards the RV
apex, which is available on all our Philips Epic 7 echocardiography
machines. Settings of the ultrasound machine were adapted to high
temporal resolution with a frame rate >100 frames/s. The
sample volume of the pulsed-wave Doppler was set to 5-7 mm following
recent suggestions of the European Association of Cardiovascular Imaging
(EACVI).17