Full text of DOI:10.1002/clc.4960250605

Clin. Cardiol. 25, 268–270 (2002)
Comparison between Transesophageal Echocardiography and Transthoracic
Echocardiography with Harmonic Tissue Imaging for Left Atrial
Appendage Assessment
´
SCIPIONE CARERJ, M.D., MARIA PAOLA TRIFIRO, M.D., ANTONIO GRANATA, M.D., FRANCESCO LUZZA, M.D., FRANCESCO ARRIGO, M.D.,
GIUSEPPE ORETO, M.D.
Department of Cardiology, University of Messina, Messina, Italy
was 3.46 ± 1.17 and 3.59 ± 1.16 cm2, respectively; LAA mini-
Summary
mum area was 1.81 ± 0.98 and 1.77 ± 0.97 cm2, respectively.
Background: Transesophageal echocardiography (TEE) is
the method of choice for evaluating both anatomy and func-
tion of left atrial appendage (LAA). In contrast, conventional
transthoracic echocardiography (TTE) does not result in im-
ages of sufficient quality to explore LAA.
Percent LAA area change was 51 ± 16.5 and 50.9 ± 16% with
HFI and TEE, respectively. Statistical analysis showed no dif-
ference between the data obtained with the two methods.
Conclusions: The results suggest that HFI TTE may be a
useful tool for the exploration of LAA.
Hypothesis: The aim of this study was to evaluate the po-
tential role of TTE with harmonic frequency imaging (HFI)
for assessing LAA normal anatomy and function.
Key words: transesophageal echocardiography, transthoracic
Methods: The study group comprised 25 patients, (9 men,
16 women, mean age 51 years, range 20–82). The TTE as-
sessment of LAA both in fundamental frequency imaging
(FFI) and HFI was performed using the apical two-chamber
view; the longitudinal two-chamber view was used for TEE
assessment of LAA. According to image quality, images were
categorized into three classes: A: good quality, B: sufficient
quality, C: poor quality.
Results: Transthoracic echocardiography conventional im-
aging allowed sufficient LAA visualization (class B) in only
5 of 25 patients (20%); the HFI resulted in adequate LAA vi-
sualization in 23 of 25 patients (92%). Images were of good
quality (class A) in 18 of 23 patients and of sufficient quality
(class B) in 5 of 23 patients. Transesophageal echocardiogra-
phy achieved good quality images in 24 of 25 patients (96%).
Average LAA maximum area determined by HFI and TEE
harmonic imaging, left atrial appendage
Introduction
Transesophageal echocardiography (TEE) is the method of
choice for evaluating both anatomy and function of left atrial
appendage (LAA),1–11 and in particular for detecting the pres-
ence of thrombi. In contrast, in the vast majority of patients
conventional transthoracic echocardiography (TTE) in funda-
mental frequency imaging (FFI) does not result in images of
sufficient quality to explore LAA.12
Due to the improved signal-to-noise ratio, harmonic fre-
quency imaging (HFI) has the potential for a better definition
of cardiac structures compared with FFI two-dimensional
(2-D) echocardiography.13–17 However, HFI has not yet been
widely validated for investigation of LAA.
The aim of this study was to evaluate the potential role of
TTE with HFI for assessing LAA normal anatomy and func-
tion. The results were compared with those obtained with TEE.
Address for reprints:
Methods
Scipione Carerj, M.D.
Via Campo delle Vettovaglie 10
98122 Messina, Italy
e-mail: scipione2@interfree.it
The study group comprised 25 patients (9 men, 16 women,
mean age of 51 years, range 20–82). Seventeen patients (68%)
were in sinus rhythm and 8 (32%) in atrial fibrillation (AF).
Indications for TEE were search for possible intracardiac
thrombi in patients with cerebral ischemia (n = 11); evaluation
Received: March 22, 2001
Accepted with revision: November 2, 2001

S. Carerj et al.: TTE with harmonic tissue imaging for LAA assessment
269
of atrial septal defect (n = 4); congenital or acquired valvular
Results
disease (n = 7); aortic dissection (n = 1). In two patients TEE
was performed as evaluation before cardioversion.
Conventional transthoracic imaging allowed a sufficient
LAA visualization (class B) in only 5 of 25 patients (20%). In
the remaining 20 patients, the fundamental frequency images
were too poor to allow LAA measurements (class C). The
harmonic imaging resulted in adequate LAA visualization in
23 of 25 patients (92%); good quality images (class A) were
obtained in 18 of 25 patients, sufficient quality images (class
B) in 5 of 25 patients, and poor quality images (class C) in 2
patients only. Transesophageal echocardiography permitted a
good quality (class A) LAA visualization in 24 of 25 patients
(96%), whereas only 1 patient had class C images. Concord-
ance between the two readers was 100% for TEE, 84% for
conventional TTE, and 92% for HFI-TTE.
Mean LAA maximum area determined by HFI and TEE
was 3.46 ± 1.17 and 3.59 ± 1.16 cm2, respectively. The
LAA minimum area was 1.81 ± 0.98 and 1.77 ± 0.97 cm2,
respectively.
The LAA area change was 51 ± 16.5% with HFI-TTE and
50.9 ± 16% with TEE. Statistical analysis showed no differ-
ence between data obtained with the two methods (Table I).
Echocardiographic images were obtained using a commer-
cial equipment (General Electrics Vingmed System Five, Hor-
ten, Norway). Fundamental frequency imaging was obtained
at 2.5–3.25 MHz, whereas HFI was obtained with ultrasound
waves transmitted at 1.7 MHz and received at 3.4 MHz. Trans-
esophageal echocardiography studies were performed using a
5 MHz mechanical multiplane transducer.
Transthoracic echocardiography assessment of LAA, both
in FFI and in HFI, was performed using the apical two-cham-
ber view (Fig. 1A) with the patient in the left lateral position.
The longitudinal two-chamber view at mid-esophageal level
was used for TEE LAA study (Fig. 1B). According to the im-
age quality, echocardiographic examinations were categorized
by consensus of two readers into three classes: good quality
(class A), sufficient quality (class B), poor quality (class C).
The following parameters were determined for LAA: maxi-
mum area, minimum area, and % area change. Each parame-
ter was calculated by two expert independent observers. For
patients in sinus rhythm, the mean value of each parameter
was obtained from three consecutive cycles, while for patients
in AF the mean value was obtained from six consecutive cy-
cles. The LAA end-systolic area, measured at the end of the T
wave on the electrocardiogram (ECG), was considered as the
maximum area. The end-diastolic area, measured simultane-
ously with the R wave of the ECG, was considered as the min-
imum area. The % area change was calculated as follows:
(maximum areaꢀminimum area)/maximum area.
Discussion
Our results demonstrate that LAA anatomic and functional
parameters obtained with HFI do not differ from those mea-
sured with TEE. This suggests that transthoracic echocardio-
gram with HFI is a good tool for LAA exploration.
Data are expressed as mean ± standard deviation (SD) and
compared by one-way analysis of variance (ANOVA) for re-
peated measures. If the normality test failed, the nonpara-
metric Kruskal-Wallis test was performed. A two-tailed test
value of p < 0.05 was considered statistically significant.
The main purpose of our research on HFI was the function-
al study of LAA rather than the detection of thrombi, since
none of our patients showed a thrombotic mass at TEE. On the
other hand, TEE continues to play an outstanding role in the
search for thrombi, also because LAA is often plurilobated,
(A)
(B)
FIG. 1 (A) Transthoracic echocardiogram in harmonic frequency imaging recorded from the apical two-chamber view. (B) Transesophageal
echocardiogram of the same patient recorded from the longitudinal two-chamber view. LA = left atrium, LAA = left atrial appendage, LV =
left ventricle.

270
Clin. Cardiol. Vol. 25, June 2002
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TABLE I Mean value ± standard deviation of left atrial appendage
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TTE
TEE
p Value
Maximum area (cm2) 3.46 ± 1.17
Minimum area (cm2) 1.81 ± 0.98
3.59 ± 1.16
1.77 ± 0.97
50.9 ± 16
0.9
0.5
0.6
Area change (%)
51 ± 16.5
Abbreviations: TTE = transthoracic echocardiography with harmon-
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so that it must be explored on several planes, a goal that can be
achieved only with multiplane TEE.18 Accordingly, TEE has
been proposed as a screening method for patients with AF as
candidates for cardioversion. Transthoracic echocardiograph-
ic imaging has been markedly improved by HFI, which ame-
liorates visualization not only of the left ventricular endocar-
dial borders but of any cardiac structure. In the evaluation of
LAA, HFI TTE has shown a good sensitivity and specificity
for assessment of LAA function and detection of thrombi.19–21
Although some authors have reported a good relationship
between LAA pulsed wave (PW) Doppler flow data obtained
with TTE and those measured with TEE,21, 22 we did not use
PW Doppler to evaluate LAA flow. This is because we ob-
served that transthoracic echo does not permit an optimal
alignment of the Doppler beam with the LAA flow, and also
because wall artifacts hamper PW Doppler flow curves.
Conclusion
Our results suggest that TTE with second harmonic imag-
ing is suitable for the functional exploration of the LAA. The
main present application of this technique could be monitoring
of postcardioversion atrial stunning, aimed at the management
of anticoagulant treatment. Further studies with larger groups
of patients will better assess the role of transthoracic evalua-
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