Clinical Trial Details
— Status: Recruiting
Administrative data
| NCT number |
NCT03117673 |
| Other study ID # |
1113/2017 |
| Secondary ID |
|
| Status |
Recruiting |
| Phase |
N/A
|
| First received |
April 6, 2017 |
| Last updated |
October 19, 2017 |
| Start date |
May 1, 2017 |
| Est. completion date |
December 31, 2020 |
Study information
| Verified date |
October 2017 |
| Source |
Medical University of Vienna |
| Contact |
Ulrike Weber, MD |
| Phone |
004340400 |
| Email |
ulrike.weber[@]meduniwien.ac.at |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
Transesophageal echocardiography (TEE) plays an important role in intraoperative monitoring
and can be used to estimate pulmonary artery pressures. An excellent correlation between
right ventricular systolic pressure (RVSP) measured by right heart catheterization (RHC) and
simultaneously estimated by transthoracic echocardiography is reported and also implemented
into the current guidelines for the echocardiographic assessment of the right heart in adults
by the American Society of Echocardiography. So far there are no studies evaluating RVSP
measured by transesophageal echocardiography (TEE) and recommendations are unclear which
transesophageal view is the best for calculation.
We want to assess if there is a difference in the systolic pulmonary artery pressure measured
invasively with a pulmonary artery catheter (PAC) and the calculated right ventricular
systolic pressure (RVSP) using transesophageal echocardiography (TEE) in 3 different views:
ME 4Ch, ME RV inflow-outflow, ME modified bicaval.
Description:
Transesophageal echocardiography (TEE) plays an important role in intraoperative monitoring
and can be used to estimate pulmonary artery pressures. In 1984 Yock et al. were the first
ones who reported an excellent correlation between right ventricular systolic pressure (RVSP)
measured by right heart catheterization (RHC) and simultaneously estimated by transthoracic
echocardiography. Later this was confirmed by several authors (3-6) and therefore also
implemented into the current guidelines for the echocardiographic assessment of the right
heart in adults by the American Society of Echocardiography. So far there are no studies
evaluating RVSP measured by transesophageal echocardiography (TEE) and recommendations are
unclear which transesophageal view is the best for calculation. More recent studies evaluated
the accuracy of echocardiography in patients with pulmonary hypertension and mostly revealed
only a moderate to weak correlation between echocardiography and right heart catheter
mesurements. One study evaluated patients with severe tricuspid regurgitation and pulmonary
hypertension and showed that pulmonary artery systolic pressure is frequently overestimated
in this population. Fewer studies reported a good correlation between these two methods.
There is also evidence that additional indices and paramenters can help to assess pulmonry
hypertension more precisely with echocardiography, such as TAPSE, Tei index or LV eccentric
index. These parameters seem to be abnormal in presence of pulmonary hypertension.
Study objectives (Hypothesis)
We want to assess if there is a difference in the systolic pulmonary artery pressure measured
invasively with a pulmonary artery catheter (PAC) and the calculated right ventricular
systolic pressure (RVSP) using transesophageal echocardiography (TEE) in 3 different views:
ME 4Ch, ME RV inflow-outflow, ME modified bicaval.
Study design
Prospective, single-center, observer-blinded, diagnostic test accuracy study.
Study population
39 patients scheduled for cardiac operation in general anaesthesia divided in 3 groups (13
per group): I. Patients with mild to moderate TI and normal RVSP (< 40mmHg) and mean PAP (<
25mmHg) (22) II. Patients with mild to moderate TI and elevated RVSP (> 40mmHg) and mean PAP
(> 25mmHg) (22) III. Patients with severe TI (defined as Vena contracta > or equal 7mm,
reversed systolic hepatic vein flow, proximal isovelocity surface area (PISA) radius > 9 mm,
and very large central jet or eccentric wall impinging jet) (1, 3)
Patients will undergo informed consent the day before surgery by one physician of the study
group.
After introduction of Anaesthesia and insertion of the central lines and the transesophageal
echo probe we will start with a standard examination. All study measurements will be done
during the standard transesophageal echocardiography (TEE) examination. Therefore, none of
the study procedures will interrupt or delay the operation or put the patients into any
additional risks.
We measure blood pressure, central venous pressure, pulmonary artery pressure and pulmonary
wedge pressure invasively via the inserted central lines. At the same time we do
echocardiographic measurements:
The right ventricular systolic pressure (RVSP) is calculated using the modified Bernoulli
equation RVSP = 4 x (MaxTRvelocity)2 + RAP. Maximal TR velocity is measured using continuous
wave (CW) Doppler. Windows used to measure the maximal TR velocity are the ME 4 chamber view,
the ME RV inflow-outflow view and the ME modified bicaval view. TR signal quality is
classified in every window according to envelope visibility as good (complete envelope),
moderate (partial envelope but prone to extrapolation) or poor (unreliable envelope or no
signal). TR severity is assessed as absent, mild, moderate or severe according to the
American Society of Echocardiography guidelines. Therefore we measure the paramenters vena
contracta, PISA and hepatic venous flow. A predefined value of RVSP > 40mmHg or mean PAP >
25mmHg is considered elevated. We also measure TAPSE, RV Tei Index and LV eccentric index for
assessment of pulmonary hypertension. During the whole TEE examination the examiner will be
blinded to the pulmonary artery pressure measured by the pulmonary artery catheter. This will
be done by a patch that covers just the pulmonary artery measurement on the OR monitor during
the TEE examination. After the examination is done the patch will be removed. A study nurse
writes down all hemodynamic measurements during the TEE examination.
All measurements will be done after induction of anaesthesia, before start of surgery and
also after surgery during skin closure when the patient is still asleep in the OR.
Statistics
The primary outcome of the study is the bias and precision of calculated RVSP with TEE
compared to measured systolic pulmonary artery pressure with PAC. The current literature
provides no information on possible differences in bias and precision of the measurement
between patients with normal, and elevated mean PAP, and those with severe TI, so our sample
size considerations are based on the whole cohort. Based on currently published
RVSP-distributions to show a clinical significant difference of more than 10% with a power of
80% we will have to include 33 patients in total. This estimation is based on a one-tailed
comparison and a probability of error of first kind of 0.05, and was calculated using G*Power
3.1.9.2. To allow for dropouts and uncertainty in this calculation, we will include 39
patients in total. Based on clinical considerations and feasibility, this will include 13
with mild to moderate TI and normal mean PAP, 13 with mild to moderate TI and elevated mean
PAP, and 13 with severe TI.
All data will be tabulated case-wise and pair-wise (i.e. PAC and TEE measurements)
Quantitative data will be expressed as mean +/- SD if normally distributed or as medians and
interquartile ranges (IQRs) if not normally distributed. Qualitative variables will be
presented as absolute and relative frequencies. Measurement from the best obtainable of the
three TEE views will be used for analysis. According to the method described by Bland and
Altman we will assess agreement between measurements: The mean difference (bias, d) as a
metric for the systematic measurement error, the SD of the differences (precision, s), and
the limits of agreement (d±2s) as metrics for scatter will be calculated. Bland-Altman plots
will be used for graphical representation.
For primary analysis, the whole cohort will be used. For secondary analysis, patients with
normal, and elevated mean PAP, and those with severe TI will be analyzed separately.
Differences between TR signal quality and of RVSP calculations between the three TEE views
will be analyzed accordingly.
Statistical analysis will be performed using Stata 12 for Windows (Stata Corp, College
Station, TX).
