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ECHOCARDIOGRAPHY (T BUCK, SECTION EDITOR)
The Contemporary Role of Intraoperative Echocardiography:
Is it Underused or Overused?
Arne Kaethner &J. Ender
Published online: 1 October 2013
#Springer Science+Business Media New York 2013
Abstract Intraoperative echocardiography has become an
invaluable diagnostic and monitoring tool. Especially during
cardiac surgery, transesophageal echocardiography has a high
capabilityto influence surgical decisions and the hemodynam-
ic management of the patients. Based on current practice
guidelines and studies, this article provides an analysis of the
contemporary role of intraoperative transesophageal
echocardiography.
Keywords Intraoperative echocardiography .
Echocardiography .Transesophageal echocardiography
(TEE) .Hemodynamic management .Cardiac surgery
Introduction
Since the introduction of transesophageal echocardiography
(TEE) into the perioperative care of cardiac surgery patients in
the 1980s [1] its popularityhas increased continuously. Guide-
lines recommending indications and use have been published
and updated by the American Society of Anesthesiology
(ASA), the Society of Cardiovascular Anesthesiologists
(SCA), the American Society of Echocardiography (ASE),
the European Association of Echocardiography (EAE), and
the European Association ofCardiothoracic Anesthesiologists
(EACTA) [2–6]. Naturally, cardiac surgery is the main appli-
cation area of intraoperative TEE using it to confirm and refine
the preoperative diagnosis, evaluate the surgical result, and
monitor the patient’s hemodynamic condition. In addition to
that, unsuspected findings might lead to a different surgical
strategy [7•,8•,9••,10••].
A recent development is the increasing frequency of trans-
catheter intracardiac procedures like aortic valve implantation,
the treatment of mitral regurgitation, and occluder placement
for atrial septal defects and left atrial appendage. Advances in
technology have made real-time 3-dimensional (RT-3D) TEE
a powerful tool complementing the differential TEE evalua-
tion of mitral and aortic valvular disease, congenital heart
disease, and aiding the guidance of transcatheter interventions
[11,12]. TEE skills are also developing among anesthesiolo-
gists involved in other major surgery, eg, neurosurgery, liver
transplantation, vascular surgery, trauma surgery, and inten-
sive care [13–17]. Despite its widespread use, very few studies
have investigated the impact of intraoperative TEE systemat-
ically [7•,8•,9••,10••]. In particular, there is a lack of
randomized controlled trials. In contrast there are innumerable
observational publications that highlight specific aspects of
TEE and its role in the perioperative setting. In view of the
constantly evolving knowledge and demands on skills in the
field of perioperative TEE, guidelines describing training
objectives and continuous quality improvement have been
issued and accreditation requirements defined [18–22]. Al-
though serious complications of TEE are very rare, contrain-
dications need to be observed carefully [23–27]. This review
article aims to provide an updated overview of the current role
of TEE in the intraoperative setting including transcatheter
intracardiac interventions.
Guidelines
Cardiac and Thoracic Aortic Procedures
Recent guideline updates outline the role of intraoperative TEE
[3–5]. TEE should be used in all open heart (eg, valve surgery)
A. Kaethner :J. Ender (*)
Department of Anesthesiology and Intensive Care Medicine,
Heartcenter, University Leipzig, Struempellstr 39, 04289 Leipzig,
Germany
e-mail: joerg.ender@medizin.uni-leipzig.de
Curr Cardiovasc Imaging Rep (2013) 6:467–472
DOI 10.1007/s12410-013-9232-2
and thoracic aortic surgical procedures, and for evaluation of
persistent life-threatening hemodynamic disturbances. For
transcatheter intracardiac interventions under general anesthe-
sia TEE may be used. The EAE and ASE recommend 3-
dimensional (3D) TEE for guidance of transcatheter mitral
and aortic valve interventions [12]. Furthermore it is deemed
advisable to include intraoperative TEE in the care of patients at
risk of myocardial ischemia, myocardial infarction, or hemo-
dynamic impairment. Based on the argument that this risk is
relevant to the majority of patients undergoing cardiac surgery,
the EAE and EACTA promote an extension of the intraopera-
tive TEE indication to all cardiac surgery patients [4].
Noncardiac Surgery
Intraoperative TEE in noncardiac surgery is used either as a
diagnostic tool in specific surgical settings or as a monitoring
tool for high risk patients undergoing major noncardiac opera-
tions. As a diagnostic tool, TEE is used to identify patients with
patent foramen ovale undergoing neurosurgical procedures in
the sitting position to avoid venous air embolism [13]andinthe
diagnosis of traumatic rupture of the aorta [15,16]. The use of
intraoperative TEE during liver transplantation has increased
between 2002 and 2008 from 21 % to 86 % [17]. However, the
majority (73 %) of the echocardiographers in this study have
applied a limited scope examination in a “rescue”situation
instead of a planned comprehensive one. As a monitoring tool,
TEE is more sensitive in detecting regional wall motion abnor-
malities due to ischemia than ECG-monitoring [28]. Assess-
ment of left ventricular preload can be done by measuring left
ventricular dimensions [2,29,30] TEE may aid optimal clinical
management by delineating causes for low cardiac output in
noncardiac surgery with potentially life-threatening hemody-
namic disturbances [31–34]. Although innumerable case re-
ports have been published there is no evidence that intraoper-
ative TEE is beneficial regarding the outcome of the patients in
noncardiac surgery.
Comprehensive vs Basic Perioperative TEE Examination
In a recently published expert consensus statement by the
ASE and the SCA the authors emphasize that the main objec-
tive of a "noncomprehensive" basic perioperative TEE exam-
ination is the intraoperative monitoring of the patient [5]. A
reduced evaluation using 11 TEE views is described and
intended not to replace but to complement comprehensive
TEE. The basic perioperative TEE is not meant to be a
"stepping stone" in the training of a TEE practitioner towards
comprehensive TEE. The focus is the assessment and moni-
toring of cardiac causes of hemodynamic and ventilatory
instability. Basic perioperative TEE is not intended to influ-
ence the surgical plan. If diagnoses beyond the scope of basic
perioperative TEE are suspected a comprehensive TEE study
should be conducted. Hence, the ASA and SCA continue to
distinguish between basic perioperative TEE as a monitoring
tool and the full diagnostic potential of a comprehensive TEE
consisting of a series of 20 cross-sectional views of the heart
and great vessels [2,5,6]. Accordingly, different training and
certification pathways are maintained [5,20,22]. In general, a
comprehensive TEE examination including all available
Doppler data is always recommended although not all com-
ponents might be necessary in every patient [21].
Documentation
All echocardiographic findings of influence to the surgical
plan need to be communicated to the surgeon in a timely
manner [21]. Following the initial verbal report, relevant
findings should be documented in a written or electronic form
for immediate reference. In addition, a written report with all
key findings must be included in the patient’s medical records
by the end of the procedure. An even more comprehensive
documentation, including all available data, may be complet-
ed within 24 hours and placed in the medical records. It is
obligatory to keep digital copies of the TEE examination and
it is desirable to specify if certain structures have or have not
been studied [4,35].
Impact on Cardiac Surgery
In cardiac and thoracic aortic operations intraoperative TEE is
of importance in confirming the preoperative diagnosis and
the graduation of pathology [7•]. Before the surgical interven-
tion it is advisable to establish a diagnostic impression under
the altered hemodynamic conditions caused by general anes-
thesia. Under general anesthesia mitral regurgitation is re-
duced by 1 severity grade in 50 % of patients with moderate
to severe mitral regurgitation [36]. Due to altered loading
conditions the color Doppler jet area and the mean vena
contracta decrease and the pulmonary vein flow pattern also
is affected [36]. Graduation of mitral regurgitation by calcu-
lating the effective orifice has also been shown to be less
severe under general anesthesia compared with preoperative
evaluation [37]. Using the baseline shift leads to a better
correlation with the preoperative graduation no matter if vena
contracta, vena contracta area, or effective regurgitation ori-
fice is used [37]. Therefore, in patients undergoing cardiac
interventions under general anesthesia (eg, mitral valve repair)
intraprocedural TEE should be performed before the interven-
tion to estimate the influence of general anesthesia in the
particular patient. This may help the correct graduation of
residual regurgitation after intervention.
468 Curr Cardiovasc Imaging Rep (2013) 6:467–472
Controlled ventilation during general anesthesia has a huge
impact on fluid responsiveness and loading conditions [31,
38,39].
Unlike transthoracic echocardiography TEE is uncomfort-
able for patients, and therefore, this procedure cannot be
repeated frequently in a conscious patient. According to the
European guidelines the TEE examination should ensure that
(A) the diagnostic goal is satisfied, (B) those structures not
well visualized by TTE are thoroughly investigated (eg, left
atrial appendage, aorta), and (C) the study is complete [4].
Depending on the tolerance of the individual patient a com-
prehensive preoperative TEE examination might not be pos-
sible. A focused TEE evaluation might not detect potentially
serious co-diagnoses that could lead to a change in the surgical
plan if known before surgery.
In the last years, a few studies have been published inves-
tigating the impact of intraoperative TEE in cardiac surgery
patients [7•,8•,9••,10••]. The impact of TEE in changing
surgical decision varies from 4.0 %–27.6 % [7•,8•,9••,10••]
with the lowest impact in patients undergoing coronary artery
bypass grafting (CABG) and the strongest impact in valve
surgery. In the study of Eltzschig, et al. [8•]intraoperative
TEE influenced surgical decision in CABG patients in 5.4 %
pre-CPB (Cardio-pulmonary bypass) and 1.5 % post-CPB
compared with 12.3 % vs 2.2 % in combined procedures. In
the study of Buck, et al. [7•]analarminghighnumberof
33.0 % of unsuspected diagnoses were made by presurgical
intraoperative TEE in patients undergoing valve surgery. In
27.6 % the surgical decision was changed.
The changes of the surgical plan due to intraoperative TEE
range from omitting planned procedures to adding procedures.
One has to distinguish between predictable and unpredictable
changes of the surgery. Patients with predictable changes of
the procedures are defined as patients in whom intraoperative
TEE was performed to confirm and/or regrade preoperatively
suspected pathology whereas unpredictable changes were de-
fined as new diagnoses of preoperatively unknown pathology.
Suspected changes were observed in 8 %–13 % of patients in
the study from Klein, et al. [9••]. Unsuspected findings range
from 6 % in the study of Skinner [10••] to 33.0 % in the study
of Buck, et al. [7•]. The reasons for unexpected diagnoses by
intraoperative TEE are manifold. Some patients might not
have been examined by preoperative TTE or TEE [9••,
10••]. Preoperative TTE is not performed in all hospitals if
only coronary surgery is planned, the left ventricular function
is assessed by other means, and clinical examination does not
suggest any valve pathology [9••]. Disease progression might
be found by intraoperative TEE if surgery is postponed too
long after the initial diagnosis [10••]. An alarming high num-
ber of unsuspected intraoperative findings seem to be due to
errors in preoperative echocardiographic evaluation [7•,10••].
This can be explained by either inadequate datasets or errors
of interpretation [10••]. On the other hand, optimal conditions
in patients under general anesthesia allow the acquisition of
higher quality images by intraoperative TEE compared with
preoperative TTE [10••,40]. As a consequence, some sur-
geons have even deliberately deferred their final decision to
the intraoperative setting [9••]. This strategy can result in an
inadequate process of risk evaluation and would render a
proper informed consent nearly impossible [41].
After the surgical intervention intraoperative TEE is a
valuable diagnostic and monitoring instrument to rule out
residual pathology and help with the appropriate therapy of
complications [7•,8•,9••]. Buck et al. [7•]reportremnant
valvular dysfunction of the operated valve in 7.8 % and
12.3 % related to other structures after CPB compared with
2.2 % altered surgical performance due to the post-CPB TEE
in the study by Eltzschig et al. [8•]. While the study results of
Buck et al. were obtained in patients referred for valve surgery,
Eltzschig et al. also included patients with combined CABG
and valve procedures. Surgical decisions are changed more
often if new intraoperative TEE findings are reported to the
surgeon before cardiopulmonary bypass [7•].
There are some limitations in interpretation of the results:
(1) The use of intraoperative TEE ranged from 23 %–55 %
of all patients undergoing cardiac surgery in the involved
institutions depending on the inclusion of only valve
surgery or both valve and CABG surgery
(2) Not all intraoperative TEE examinations fulfilled the
goals of a comprehensive TEE examination pre- and
postintervention
In elective surgery it, therefore, is a prerequisite to make
every effort to establish the correct diagnosis at the very latest
on the day prior to the operation in order to provide the
medical team and the patient with the necessary information.
As a further consequence, quality standards of preoperative
echocardiography need to be kept high [7•,10••].
The bottom line of all these study results is that intraoper-
ative TEE has an important impact on surgical decisions.
Unexpected diagnoses are more likely to be found by a
comprehensive TEE evaluation attempting to obtain all 20
recommended views including Doppler data. In 2009 a survey
at the annual meeting of the Cardiac Anesthesia Working
Group of the German Societyof Anesthesiology and Intensive
Care Medicine revealed that intraoperative TEE was only
applied in 67 % cases of valve surgery [42]. In 43 % of the
departments TEE was only occasionally performed by a cer-
tified examiner. All standard views were routinely obtained in
17 % of the departments. Digital images were stored in 61 %
of the departments and 51 % only saved abnormal findings.
These findings are in accordance with the data of Wax et al.
[17] who reported that a comprehensive TEE- examination
was performed only in 27 % compared with 73 % focused
examination. The acquisition of the recommended standard
views alone does not necessarily result in correct diagnoses.
Curr Cardiovasc Imaging Rep (2013) 6:467–472 469
Profound knowledge and experience based on structured
training is vital to interpret the obtained dataset. Therefore,
recommendations for structured training programs have been
issued that define the minimum requirements for certification
[2,20,21]. Despite a 17-year history of practice guidelines the
German survey in cardiac anesthesia departments showed that
in 43 % of the departments TEE was only occasionally
performed by a certified examiner [42]. The percentage of
certified examiners in noncardiac operations (ie, liver trans-
plantation) is even lower (12 %, [17]).
3D TEE
The technical development of real-time 3-dimensional (3D)
TEE probes and advances of computer technology have intro-
duced an exciting and very useful utility into the intraoperative
setting. In 2012, the American Society of Echocardiography and
the European Association of Echocardiography have published
"recommendations on image acquisition and display using 3-
dimensional echocardiography" [12]. Echocardiographers need
to learn new skills in order to acquire good quality 3D TEE
datasets and extract the relevant information by using the appro-
priate software tools. There is an advantage of 3D TEE over 2D
TEE in examining left ventricular mass and ejection fraction [11,
43–46]. 3D TEE also should be included in the assessment of
mitral valve pathology and the guidance of transcatheter inter-
ventions [47–50]. The same recommendation applies to aortic
stenosis and transcatheter valve insertions as well as prosthetic
valves [48,51,52]. At present, 3D TEE is regarded comple-
mentary to 2D TEE and has not revealed its full potential [11].
Further indications will most certainly emerge as the evolution
of 3D ultrasound technology presses on.
Conclusions
In light of the rate of unsuspected findings in the different
studies leading to alteration of surgical decisions, the current
role of intraoperative TEE cannot be overestimated.
The full impact of intraoperative TEE will only be gained if
the aim is a comprehensive examination performed or at least
supervised by certified examiners in combination with a high
reporting standard in patients undergoing cardiac interven-
tions under general anesthesia before and after the interven-
tion. Contraindications need to be observed. A high level of
practitioner qualification helps to minimize adverse effects. In
summary, the answer to the raised question is: based on the
current literature intraoperative TEE is still underused.
Compliance with Ethics Guidelines
Conflict of Interest Arne Kaethner declares that he has no conflicts of
interest. Joerg Ender declares that he has no conflicts of interest.
Human and Animal Rights and Informed Consent This article does
not contain any studies with human or animal subjects performed by any
of the authors.
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