European Journal of Echocardiography 2004 5(6):455-468; doi:10.1016/j.euje.2004.04.007
© 2004 by European Society of Cardiology
Copyright © 2004, The European Society of Cardiology
The impact of transesophageal echocardiography on daily clinical practice
H.P. Kühl* and
P. Hanrath
Medical Clinic I, University Hospital, Aachen, Germany
Received 10 February 2004; .
* Corresponding author. Tel.: +49-241-8088722; fax: +49-241-8082303. hkuehl{at}ukaachen.de
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Abstract
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The development of transesophageal echocardiography (TEE) almost
20 years ago has tremendously widened the diagnostic potential
of cardiac ultrasound and has, without doubt, strongly improved
our pathophysiological understanding of many cardiovascular
diseases such as aortic dissection, mitral valve disease or
ischemic stroke. Especially the introduction of multiplane transducers
that allow imaging of the cardiac structures from various scan
plane orientations has yielded a level of diagnostic accuracy
that is seldom attained by other imaging modalities. The outstanding
image quality as well as the high temporal and spatial resolution
provided by TEE renders the method especially suited to visualize
small and rapidly moving structures, such as left atrial thrombus
formation and valvular vegetations. In addition, TEE is exceptional
in its capability to scan the heart from perspectives that cannot
be easily attained by any other modality, thus enhancing its
diagnostic yield. In the last few years the clinical application
of TEE has been extended from a pure diagnostic tool to an indispensable
monitoring adjunct for percutaneous interventional procedures
as well as for the intra- and peri-operative monitoring in the
operating theatre and on the intensive care unit.
In the surroundings of emerging sophisticated technologies to image the heart and the great vessels within the thorax such as multi-slice computed tomography and cardiovascular magnetic resonance imaging TEE asserts a firm place in the diagnostic armamentarium for the cardiologist. This review will focus the impact of TEE in daily clinical practice and on possible future applications of the technique.
Keywords: Transesophageal echocardiography; Source of embolism; Infective endocarditis; Aortic dissection; Prosthetic heart valve; Left ventricular function
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Current indications for TEE
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The indications for a TEE study have widened continuously in
the recent years. To date TEE is indicated in almost any condition
in which transthoracic echocardiography (TTE) fails to provide
conclusive diagnostic information or where TTE is not possible
(i.e. during surgery). Moreover, TEE is indicated whenever it
is expected to add important information beyond that obtained
by TTE and whenever the clinical question is important enough
to warrant the small risk and discomfort associated with the
procedure.
Fig. 1 demonstrates the distribution of the main
indications for a TEE study as performed in 862 patients at
the University Hospital, Aachen, Germany. The principal indications
for a TEE study published in the Guidelines from the Working
Group on Echocardiography of the ESC are summarized in
Table 1.
1
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Figure 1 Frequency distribution of the indications for a TEE study assessed in the cardiology department of the University Hospital Aachen, Germany. Searching for cardiac sources of emboli was by far the most common indication for a TEE study.
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Cardiac sources of embolism
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Stroke is among the leading causes of death in the Western world.
Almost 80–85% of all strokes are of ischemic origin and
up to 20% of cerebral ischemic events are presumed to have a
cardio-embolic origin.
2 TEE is highly sensitive in depicting
possible sources of cardiac embolism with a diagnostic yield
that may exceed 50%.
3 The high diagnostic sensitivity in determining
the sources of embolism is based on the proximity of the esophagus
and the heart allowing for a high-resolution, detailed visualization
of the posterior cardiac structures including the atria, left
atrial appendage, interatrial septum with accurate delineation
of its anomalies, and left-sided heart valves as well as atherosclerotic
lesions within the thoracic aorta. The search for cardiac sources
of embolism is currently the leading indication for a TEE study
in many centers.
TEE has considerably improved our pathophysiological understanding and diagnostic potential of cardiovascular related embolic events. Potential sources of embolism include intracardiac and aortic masses such as thrombi, tumors or vegetations as well as abnormalities associated with the atrial septum, which may act as a conduit for thrombi of the venous system, such as patent foramen ovale—isolated or in combination with an atrial septal aneurysm—and atrial septal defects (Fig. 2). In addition, there are other conditions, which may be associated with an enhanced potential for thrombus formation such as spontaneous echo contrast within the left atrium, which is accurately identified by TEE.
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Figure 2 Rare finding of a large straddling thrombus (only partially visualized) in a patent foramen ovale in a patent with severe acute pulmonary embolism. IAS = interatrial septum; LA = left atrium; RA = right atrium; AoA = ascending aorta.
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Atrial fibrillation is associated with a two-fold increase in
cardiovascular mortality and a five- to six-fold increased risk
for cardio-embolic stroke.
4 The loss of mechanical atrial function
results in an altered hemodynamic state with stasis of blood
flow which favors the formation of thrombi, especially in the
left atrial appendage (
Fig. 3). Several clinical conditions
such as advanced age, presence of mitral stenosis, hypertension
or an impaired left ventricular function substantially increase
the risk for atrial thrombus formation in the presence of intermittent
or permanent atrial fibrillation.
4 Embolization of left atrial
thrombi in atrial fibrillation account for >45% of cardiogenic
thromboemboli. Among patients presenting with new-onset atrial
fibrillation TEE studies have demonstrated an incidence of atrial
thrombi in 12–15% of patients
5,6 and an incidence of 27%
in patients with chronic atrial fibrillation.
7 The frequency
approaches 50% among patients presenting with atrial fibrillation
in the setting of acute clinical thromboembolism.
8 Due to the
proximity of the echoscope to the left atrium and atrial appendage
TEE is the method of choice for the detection of atrial thrombi
in patients with atrial fibrillation. In addition, the combination
of TEE and pulsed wave Doppler has further augmented our understanding
of the thromboembolic risk of patients with atrial fibrillation.
9 Characteristic findings identified by TEE indicating a low-flow
state in the left atrium include an enlarged atrium, spontaneous
echo contrast and a reduced flow rate (<25 cm/s) within the
enlarged left atrial appendage (
Fig. 3). Low-flow conditions
are associated with an increased thromboembolic risk even in
the absence of a left atrial thrombus and are also associated
with a high recurrence rate of atrial fibrillation after successful
cardioversion. Despite restoration of sinus rhythm the increased
thromboembolic risk persists early after cardioversion which
is believed to be caused by "atrial stunning".
10 TEE has proven
useful to guide cardioversion in patients with atrial fibrillation.
In the ACUTE trial patients were randomized to a conventional
treatment strategy consisting of a prolonged anticoagulation
treatment period without TEE prior to cardioversion and to a
TEE-guided strategy with a short-term anticoagulation treatment
preconversion.
11 Although there were no differences in the rate
of embolic events after cardioversion between the two treatment
groups, bleeding complications were significantly lower in the
TEE-guided group.
11 In combination with low-molecular weight
heparin TEE-guided cardioversion may be considered a safe and
clinically effective alternative to the conventional treatment
strategy for patients with atrial fibrillation, as has been
recently demonstrated in the ACE-trial.
12
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Figure 3 Echocardiographic findings demonstrating a low-flow state in the left atrial appendage in patients with chronic atrial fibrillation. Left panel: swirling and smoke-like spontaneous echo contrast (SEC, notched arrowheads) as well as a thrombus can be detected in the left atrial appendage. Right panels: pulsed wave Doppler curves demonstrating normal atrial appendage flow velocities (>25 cm/s) in patients with normal sinus rhythm (upper panel) and decreased flow velocities (<25 cm/s) in a patient with chronic atrial fibrillation (lower panel).
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Atherosclerotic lesions of the aorta detected by TEE have been
recognized as an important cause of stroke and peripheral embolic
disease which may lead to severe neurological deficits as well
as multi-organ failure and death.
13,14 Using TEE the prevalence
of thoracic aortic atheromas is 27% in patients who have experienced
a previous embolic event.
15 When atheromas are present the incidence
of stroke is 12% in one year and as many as one-third of patients
with significant aortic plaques may experience either a stroke
or a peripheral embolism in the same time period.
15 Plaque thickness
and plaque composition as assessed by TEE have been identified
as major risk factors for embolic complications (
Fig. 4). A
strong association has been demonstrated between protruding,
non-calcified plaques
4 mm in the aorta detected by TEE and
the risk of ischemic stroke and peripheral embolism.
14,16 Moreover,
as many as 25–50% of protruding plaques may demonstrate
superimposed mobile thrombi ranging from one to several centimeters,
which impart a high embolic risk.
15 Atheromas in the aortic
arch and ascending or descending aorta identified by TEE may
be the cause of many otherwise unexplained strokes (so-called
"cryptogenic strokes").
Aortic atheromas are also an important cause of stroke during
open heart surgery.
17 The increased number of elderly patients
with severe atheromatous disease of the aorta has focused clinical
interest on the management of severe atheroma of the ascending
aorta and the associated risk of intraoperative embolization.
Simple palpation of the aorta during surgery underestimates
the degree of disease.
18 In contrast, intraoperative TEE provides
unique information on the localization and composition of aortic
atheroma which may alter the conduct of the operation, especially
with regard to the site of cross clamping of the aorta. If atheromas
are detected in the arch or in the ascending aorta the intraoperative
stroke rate is significantly increased compared to patients
without atheroma.
17 Moreover, the in-hospital mortality rates
of patients with intraoperative stroke approaches 40% and survivors
often remain severely disabled.
19 In addition, the in-hospital
mortality rate for patients with aortic arch atheromas detected
by TEE is almost 15%.
19 Thus, patients with atheromas of the
aorta detected by TEE represent a high-risk group for cardiac
surgery. This prognostically useful information provided by
TEE must be considered in the risk-benefit analysis for patients
who undergo elective cardiac surgery.
In younger patients <50 years with an otherwise unexplained ischemic embolic event an increased prevalence of a patent foramen ovale (PFO) as a potential mechanism for a paradoxical embolism has been reported.20,21 TEE is considered the imaging modality of choice for the identification of a PFO. Detection of a PFO is best accomplished using peripheral venous injections of contrast material (i.e. agitated saline or polyoxygelatine) in combination with a strenuous Valsalva maneuver allowing for the direct visualization and quantitation of the atrial right to left shunt (Fig. 5). Moreover, TEE may identify additional risk factors such as a large shunt (either spontaneously or after provocation), a larger PFO size 4 mm, or an atrial septal aneurysm (ASA, Fig. 5). Several studies have shown that these abnormalities are linked to an increased likelihood for paradoxical embolic events as well as to an increased risk for recurrent ischemic events.22–24 TEE may also be helpful in selecting the appropriate treatment strategy for patients with presumed paradoxical embolic events: patients with a small PFO and no ASA are at low risk for recurrent embolic events and may be safely treated with antithrombotic therapy alone, while patients with a larger PFO in combination with ASA are at high risk for recurrence and may need more aggressive treatment such as anticoagulation or interventional closure of the PFO.24 Thus, TEE is very helpful in identifying patients with a potential paradoxical embolic event, to stratify these patients according to their risk for recurrent events and to guide therapy. Moreover, TEE allows for accurate delineation of the anatomy of the interatrial septum and its neighboring structures, which is important for the planning of interventional percutaneous PFO closure.
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Figure 5 Morphological alterations of the interatrial septum (IAS). Left panel: a patent foramen ovale (PFO) is detected after injection of echocardiographic contrast material into an antecubital vein. The right atrium (RA) is completely filled with contrast material. The appearance of a cloud of contrast bubbles (thick white arrow) in the left atrium (LA) through the IAS can be clearly appreciated. Right panel: bulging of the IAS towards the LA is shown corresponding to an atrial septum aneurysm (ASA). AoA = ascending aorta.
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Infective endocarditis
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Infective endocarditis is a life-threatening disease with significant
morbidity and mortality rates as high as 20–25%.
25 There
is still a continuous rise in the incidence of infective endocarditis
despite significant improvements in diagnosis and treatment
which is mainly caused by increasing numbers of intravenous
drug abusers, patients with prosthetic heart valves and elderly
patients. Improvement of patient outcome requires accurate diagnosis,
early recognition of complications and timely initiation of
treatment. Echocardiography has dramatically improved the evaluation
of infective endocarditis and is now considered as an indispensable
tool in the diagnosis and management of suspected or established
endocarditis. Especially the development of TEE has greatly
improved the detection of small vegetations,
26 prosthetic valve
endocarditis,
27 paravalvular abscess
28 as well as recognition
of artifacts and normal cardiac structures that may be mistaken
for endocarditis. The immense diagnostic potential of echocardiography
and especially TEE in the setting of infective endocarditis
has led to a revision of the diagnostic criteria to include
echocardiographic findings as a major diagnostic criterion.
29
Compared to transthoracic echocardiography TEE has considerably facilitated the process of making the correct diagnosis in the context of suspected endocarditis because TEE provides a significant improvement in sensitivity, primarily at detecting small vegetations (<5 mm) which are difficult to visualize by TTE.26 Moreover, TEE is superior to TTE in the visualization of complications of endocarditis such as paravalvular abscess (Fig. 6), fistulas and perforations, prosthetic valve dehiscence and paravalvular regurgitation.27 The improvement in imaging with TEE is most striking in the detection of prosthetic valve endocarditis (Fig. 7), especially of the mitral valve, due to enhanced visualization of the left atrial side of the prosthetic valve.28
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Figure 6 Long-axis views of the aortic valve demonstrating a severe aortic valve endocarditis with abscess formation in an intravenous drug abuser. Left panel: a large vegetation (thin arrow) is detected on the right coronary and non-coronary cusp of the aortic valve. A cavity has formed adjacent to the right coronary cusp corresponding to a large abscess (white thick arrows). Right panel: the inflammatory process has resulted in destruction of the right coronary cusp with loss of coaptation between the valve cusps (broken thin arrow) resulting in severe aortic insufficiency. LVOT = left ventricular outflow tract; LA = left atrium; AoA = ascending aorta.
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Figure 7 Endocarditis of a bileaflet aortic valve mechanical prosthesis. Left panel: long-axis view demonstrating a vegetation on the aortic side of the valve prosthesis. Right panel: on the short-axis view it is apparent that vegetations are present on both prosthetic leaflets of the mechanical aortic valve. AoA = ascending aorta; AV = aortic valve; LA = left atrium.
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Based on these facts—in the setting of suspected endocarditis—and
according to the guidelines of the American Heart Association,
TEE is the primary imaging modality of choice, especially in
patients with artificial valves, in patients with intermediate
or high clinical suspicion of infective endocarditis and in
patients with high risk of infective endocarditis related complications
such as
Staphylococcus aureus bacteremia.
30
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Prosthetic heart valves
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Prosthetic valve abnormalities, dysfunction or other associated
pathologies are being recognized in an increasing number of
patients as the rate of valve replacement surgery grows.
TEE has gained increasing acceptance as a valuable method to assess prosthetic valve function. Compared to transthoracic echocardiography TEE provides improved signal-to-noise ratio and improved spatial resolution using high frequency transducers. Moreover, improved acoustic penetration through mechanical valves has made TEE the first choice modality for the investigation of patients with prosthetic valves, especially in those with mechanical mitral valve replacement (Fig. 8). Additional pathomorphological findings such as thrombi in the left atrium and left atrial appendage as well as valvular or paravalvular leakages can be easily detected by TEE. These findings are nearly always missed by TTE, especially in mechanical prostheses, because of shadowing. However, for patients with both aortic and mitral valve mechanical prostheses a combination of TTE and TEE imaging might be indicated for complete evaluation of valve function and morphology of both valves. In patients with biological valve prostheses, TEE can readily identify degenerative valve alterations such as thickening or calcification of the leaflets, leaflet tears or prolapse.
Prosthetic valve thrombosis is an infrequent but potentially
life-threatening complication with a reported incidence of 0.5–8%
of left-sided and up to 20% of tricuspid valves.
31–33 Thrombolytic therapy is a therapeutical alternative to re-operation
which is associated with significant morbidity and mortality.
34 However, thrombolysis is associated with an unpredictable risk
of embolization of thrombus material and bleeding.
35 A recent
study has demonstrated that thrombus size, as imaged by TEE,
is an independent predictor of outcome of patients with prosthetic
valve thrombosis.
36 In that study the rate of death and complications
were low in patients with a thrombus size <0.8 cm
2 irrespective
of functional class while it was increased in those with a thrombus
size
0.8 cm
2.
36 Thus, TEE can identify low-risk groups suited
for thrombolysis and it is therefore recommended in the management
of prosthetic valve thrombosis.
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Aortic dissection
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The incidence of aortic dissection is approximately 5–30
per one million people per year.
37 Symptom onset is often sudden
and may mimic acute myocardial infarction, pulmonary embolism
and cardiogenic shock. Thus, a high level of suspicion is necessary
for establishing the correct diagnosis and for choosing the
optimal treatment. Complications often occur randomly and the
outcome is frequently fatal. Twenty-one percent of patients
with aortic dissection die before hospital admission.
38 The
mortality rate for patients with untreated proximal aortic dissection
has been reported to increase by 1–3% per hour and is
approximately 25% during the first 24 h after initial presentation;
70% of patients with untreated proximal aortic dissection die
within the first week and less of 10% of these patients live
for 1 year.
39,40
The most common mechanism for aortic dissection is believed to be associated with rupture of the intima followed by cleavage formation and propagation of the dissection into the media.41 However, TEE has enhanced and extended our present understanding of the pathogenesis of aortic dissection. Based on TEE observations intramural hematoma as well as penetrating atherosclerotic ulcers are now believed to be major precursors of aortic wall dissection.42 These conditions may lead to perforation of the intima and initiate dissection. A recent study using TEE has shown that intramural hematoma is associated with a poor outcome, especially when the ascending aortic is affected and when the disease has resulted in a dilatation of the ascending aorta 50 mm.43
Although CT, MRI and TEE have a similar diagnostic yield for the detection of aortic dissection with high sensitivities and specificities,44 the latter technique offers unique advantages that render the method the diagnostic modality of choice for the identification of aortic dissection. As a bed-side technology TEE allows immediate examination of hemodynamically compromised, unstable patients on the intensive care unit. Patients with acute proximal aortic dissection who are candidates for surgery can be directly carried to the operating theatre, thus saving valuable time and increasing the safety for the patient. In combination with Color-Doppler flow TEE possesses the ability to identify the exact pathomorphology of the dissection including the entry and re-entry sites of dissection (Fig. 9) and thrombosis of the false lumen, as well as associated complications such as involvement of the coronary arteries and arch, the presence, extent and hemodynamic significance of pericardial effusion and the presence and severity of aortic regurgitation. The most important diagnostic finding of aortic dissection that can be seen on TEE is the presence of an undulating intimal flap within the aortic lumen that differentiates a false (usually larger) lumen from a true (usually smaller) lumen (Fig. 10). In addition TEE can be used for follow-up examinations after surgical or medical treatment to detect late complications such as aneurysm formation at the site of operation or to provide useful prognostic information in terms of progression of thrombosis in the false lumen.
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Figure 10 Acute aortic dissection. Upper panel: long-axis view of the ascending aorta showing a dissection membrane arising shortly above the aortic valve. Lower panels: short-axis views of the ascending (left) and descending (right) aorta demonstrating the typical finding of an undulating intimal flap within the aortic lumen that differentiates a false (usually larger) lumen from a true (usually smaller) lumen.
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Peri-operative application
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Intra-operative applications of TEE enable continuous monitoring
of the surgical procedure without disturbing the sterile field,
in contrast to epicardial echocardiography. During myocardial
revascularization TEE allows for the non-invasive evaluation
of global left ventricular function. In addition, it can accurately
identify regional wall motion abnormalities as possible marker
of myocardial hypoperfusion before and immediately after bypass.
45 In the growing area of "off-pump" bypass surgery TEE is an indispensable
tool for monitoring of the success of the surgical procedure.
TEE provides information of greatest value in reconstructive mitral valve surgery. The pathomorphology of the diseased valve and subvalvular apparatus can be clearly defined by TEE which may have important impact on the feasibility and surgical strategy during operation.46 This is of relevance in surgical correction of mitral regurgitation because valve repair has been shown to be more beneficial than valve replacement and to improve long-term survival.47 Decisions based on TEE made at the time of operation may effect on both early and late survival and the need for re-operation or replacement of the valve during the operation.46
High-risk patients with poor ventricular function undergoing coronary bypass surgery often receive hemodynamic support in the peri-operative period by implantation of an intra-aortic balloon pump. TEE is very helpful in guiding correct positioning of the balloon tip in the descending aorta during insertion. Moreover, it allows for the detection of severe atheroma, which may prohibit implantation to avoid potential embolic complications. In the early postoperative period TTE is often unsatisfactory after open chest surgery for various reasons including the presence of air and tubes in the operative field. Therefore, TEE is the best imaging modality for imaging of the heart postoperatively. It is especially useful for the evaluation of global and regional function, assessment of the filling status of the left ventricle and detection of pericardial effusion or hematoma within the pericardial space after operation.
In the intensive care unit TEE is of great clinical importance to image the heart in intubated and ventilated patients where TTE is often not successful. In patients presenting with hypotension and low cardiac output TEE monitoring of the left ventricle allows immediate discrimination between hypovolemia, depressed myocardial functional or hyperdynamic failure as the underlying mechanism as well as the exclusion of cardiac tamponade. Moreover, TEE provides valuable additional information on the etiology of cardiac decompensation allowing for detecting valvular heart disease, abnormal regional function and abnormal diastolic function. Thus, immediate availability of the hemodynamic and anatomic information gained from TEE may permit rapid and adequate therapeutic intervention.48 With the introduction of a miniaturized monoplane TEE probe, which allows nasal insertion, continuous monitoring of during operation and in the postoperative period seems feasible. In summary, TEE is now considered an indispensable tool in the perioperative management of patients undergoing major cardiac surgery as well as in the management of patients with heart disease in the intensive care unit.
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Guiding of catheter based interventions
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Catheter based interventions for the treatment of congenital
heart disease or acquired disease of the aorta in pediatric
and adult patients represent an arena in which the use of TEE
guidance is of great importance. The combined use of X-ray and
TEE imaging is in many cases mandatory for the success of the
interventional procedure. It provides instantaneous recognition
of the morphological and hemodynamic result and its complications.
Specific applications include transseptal puncture, catheter
positioning during radiofrequency ablation, balloon atrial septostomy,
balloon positioning during pulmonary/aortic or mitral valvuloplasty
and transcatheter closure of atrial and ventricular septal defects
as well as of PFO. Moreover, stenting of the aorta in selected
patients with aortic dissection becomes an important treatment
option to improve prognosis in patients who are no candidates
for surgery.
49 Aortic stent-graft placement allows for occlusion
of the intimal entry tear by implantation of a membrane-covered
self-expanding stent-graft to initiate progressive thrombus
formation within the false lumen and thereby avoid complications
such as aortic dilatation, aneurysm formation as well as rupture.
Results obtained by TEE are important in patients with a PFO and a paradoxical embolic event to assess the exact morphology of the atrial septum and to evaluate the suitability for percutaneous closure of the PFO. Although the procedure might be successfully performed without TEE guidance, the direct visualization of the anatomy of the atrial septum and of the spatial relation between the device and the septum during implantation may increase the success rate as well as the safety of the procedure. In the setting of an atrial septal defect a pre-interventional TEE examination is a prerequisite to define the exact morphology and site of the atrial septal defect as well as its relation to neighboring structures such as the mitral and tricuspid annulus, coronary sinus and pulmonary veins. TEE is an indispensable tool during percutaneous closure of an atrial septal defect to guide correct positioning of the device, to recognize malpositioning and to assess potential or imminent complications (Fig. 11).50 In the post-interventional control TEE is necessary to detect complications such as thrombus formation (Fig. 12) on the device, residual shunting, strut fractures or dislocation of the device.51
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Figure 11 Large atrial septal defect (white thick arrow pointing to the defect of the interatrial septum) before (left panel) and after interventional closure (right panel) with the occluder device located in the correct position. LA = left atrium; RA = right atrium; VCS = vena cava superior.
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A promising new field for TEE may be TEE-guided cardioversion
via the same probe using a condome-like sheath with incorporated
electrodes.
52,53 This would allow for exclusion of atrial thrombi
and electrical cardioversion via the esophagus within the same
session. Data in experimental animals have demonstrated a 4-fold
reduction in the cardioversion threshold during esophageal cardioversion
compared to the external approach.
52 This technique would not
only contribute to save time and costs but also to reduce discomfort
for the patients who can be safely treated in only one session
needing only one sedation.
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Summary
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TEE has opened a new window to the heart. Its success rate is
impressive. In less than two decades it has become an integral
part of pediatric and adult cardiology as well as cardiac surgery
and anesthesiology. The range of indications has broadened since
its introduction almost 20 years ago. Technical improvements
in transducer technology and the development of miniaturized
matrix transducers might in the near future allow for a real-time
three-dimensional view onto the heart even from the esophagus.
It is anticipated that this will further increase the diagnostic
potential of the technique and its importance for guiding of
therapeutical procedures. The combination of unique morphological
and hemodynamic information of exceptional diagnostic quality
and the possibility to use this diagnostic method as a bed-side
tool in the intensive care unit and the operating theatre guarantee
that this diagnostic modality will maintain its firm place in
the diagnostic armamentarium of cardiologists and anesthesiologists,
beside novel and emerging imaging modalities such as cardiac
magnetic resonance imaging and multi-slice computed tomography.
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Abstract
Current indications for TEE
