Left ventricular ejection fraction is increased during transesophageal echocardiography in patients with impaired ventricular function

Left ventricular ejection fraction is increased during transesophageal echocardiography in patients with impaired ventricular function Transesophageal echocardiography (TEE) is increasingly being used to assess left ventricular function (LVF). However, little data exist on the quantitative accuracy of this technique and its influence on LVF. Thus 50 ambulatory adult patients (mean age 62 f 15 years) were studied with transthoracic echocardiography (TTE) immediately before, before the end, and 10 minutes after TEE. Left ventricular ejection fraction (LVEF) was calculated using the modified Simpson’s method. In subjects (n = 24) with impaired LVF (LVEF < 55% by TTE), TTE-derived LVEF increased from 37 + 13% to 45 -I 15% (p < 0.001) during TEE. In 13 of 24 subjects with abnormal LVF, LVEF significantly increased during TEE as defined by an increase in LVEF by at least 5 ejection fraction units. In four of these subjects LVF normalized during TEE. LVEF was unchanged during and after TEE in the subjects (n = 26) with normal LVF (LVEF > 55%). An excellent correlation was found between LVEF derived by TEE and that derived by lTE performed during TEE (r = 0.93, SEE = 6.6%, p < 0.001). LVEF determined by TEE compared well with that derived by TTE and should be a useful measure of global left ventricular function. However, an increase in LVEF during TEE occurs in over 50% of patients with impaired LVF and may be important to consider in individual subjects. (AM HEART J 1992;123:1005.)

Marcus F. Stoddard, MD, Susan Dillon, Joel Kupersmith, MD. Louisuille, Ky.

RDCS, Geoffrey Peters, MD, and

Transesophageal echocardiography (TEE) is a rapidly expanding cardiovascular diagnostic technique that is increasingly being used to assess left ventricular systolic function (LVF). However, little data exist on the quantitative accuracy of this technique.lv4 In addition, it is unknown if the physical and emotional stress of the procedure alter resting LVF. We postulated that LVF is enhanced during the transesophageal echocardiographic procedure, potentially because of sympathetic nervous system stimulation. Intravenous sedation may be an important method of blunting the potentially enhanced LVF during TEE, but it is not given routinely by all groups performing the procedure.5 The aims of the present study were to determine: (1) if TEE enhanced LVF, (2) if intravenous sedation affected the influence of TEE on LVF, and (3) if TEE-derived left ventricular ejection fraction is comparable with that of transthoracic echocardiography (TTE)-derived ejection fraction.

From

the Cardiovascular

Received

for publication

Reprint requests: sion of Cardiology, 4/1135354

Division. April

University 11, 1991;

accepted

of Louisville. Sept.

23, 1991.

Marcus F. Stoddard, MD, University of Louisville, 550 S. Jackson St., Louisville, KY 40202.

Divi-

METHODS

Study patients. Fifty patients (41 men and 9 women) with a mean age of 62 f 15 years (range 22 to 84 years) scheduledfor transesophagealechocardiography met inclusionand exclusioncriteria and madeup the study group. Inclusion criteria included sinusrhythm, ambulatory state, and a prior two-dimensional transthoracic echocardiographic study demonstrating adequate parasternal and apical windows for good delineation of left ventricular endocardial edges.Exclusion criteria included a contraindication (e.g., severechronic obstructive pulmonary disease) or a specific indication (e.g., excessivepreprocedural anxiety) for intravenous midazolam sedation,a segmentalleft ventricular wall motion abnormality (e.g., akinesis)as opposedto global left ventricular systolic dysfunction, paradoxic septal motion, @-blocker medication usage, and technically inadequate TTE or TEE. The study was approved by our Human Studies Committee. Informed consentwasobtained from all patients before their enrollment. Study protocol. All patients fasted for a minimum of 4 hours. Subjects were randomly assignedto receive or not receive intravenous sedation with midazolam. Peripheral intravenous accesswasestablishedand 2 L of 0s per nasal cannula was routinely used. The oral pharynx was anesthetized by the patient’s gargling and swallowing15 ml of 2% viscous lidocaine and by spraying the pharynx with topical lidocaine. Subjects were placed in a left lateral de1005

1006

Stoddard

et al.

American

Table I. Influence of transesophageal

echocardiography

with and without

sedation on left ventricular TEE

L VF group

Sedation

No.

Control

Abnormal Abnormal Abnormal Normal Normal Normal

Yes/No Yes No Yes/No Yes No

24

37 40 34 67 68 66

LVF, Left ventricular removing TEE probe; *p < 0.01, tp < 0.002,

function;

TEE,

‘I’TE, transesophageal

11 13 26 15 11 and transthoracic

After TEE, performed 10 minutes after removing $p < 0.001 versus control; §p < 0.05 versus during

During

+ 13 * rt + k

fraction

14 6 5 6 respectively;

TEE

During

systolic function

(5%) After

45 * 15$ 50 * 13* 40 + 15f 70 * 8 71 + 6 70 ? 10

k 11

echocardiography, TEE probe. TEE.

cubitus position and were encouraged to relax. Transthoracic two-dimensional (2D) and color-flow Doppler (CD) echocardiography were performed after a minimum of 5 minutes. In subjects randomized to be sedated, intravenous midazolam was given to achieve at least slurred speech and drowsiness, but more typically sleep was induced when the patient was not aroused. The TEE probe was gently introduced into the patient’s esophagus, aided by the patient’s swallowing. At the completion of TEE imaging before and 10 minutes after removing the TEE scope, transthoracic 2D and CD echocardiography were repeated. Systemic blood pressure was measured every 3 minutes throughout the procedure and during the performance of each TTE using a Dinamap automated machine (Dinamap model 1846, Critikon, Inc., Tampa, Fla.). Patient tolerance score. At the conclusion of the TEE, two physicians by consensus judged patient tolerance of the procedure as either very well (l+), good (2+), fair (3+) and poor (4+). Patients not receiving sedation were independently questioned on their subjective tolerance of the procedure using the same scale. Subjects receiving sedation were typically amnestic and felt unreliable to judge tolerance. Transesophageal echocardiography. TEE was performed using a commercially available echocardiographic machine (Model 77020, Hewlett-Packard Co., Andover, Mass.) with a 64-element, 5.0 MHz phased-array monoplane scope. After insertion, the scope was manipulated to obtain the following sequence of views: four-chamber, modified long-axis, transgastric short-axis at the mitral valve and midpapillary muscle levels, and a repeat fourchamber view. Care was taken to maximize the left ventricular length during the four-chamber view, which frequently requires simultaneous manipulation of the anteflex-retroflex and left-right knobs. The transgastric shortaxis and repeat four-chamber views were used to calculate ejection fraction and volumes by TEE. Transthoracic echocardiography was performed immediately after obtaining the last TEE images of the left ventricle but before removing the probe. Echocardiographic studies were recorded on l/X-inch VHS videotape for subsequent review and analysis. Transthoracic echocardiography. 2D and CD echocar-

ejection

April 1992 Heart Journal

41 43 39 67 68 67 ‘TEE, performed

TEE _t * I! k t i

13-F 12s 14t I 5 8

immediately

before

diography were performed using a Hewlett-Packard echocardiographic machine (Model 77020, Hewlett-Packard Co.) with a 2.5 MHz transducer. Conventional 2D views were obtained of the parasternal long-axis and of the short-axis at the mitral valve and midpapillary muscle levels; conventional apical four-chamber, five-chamber, twochamber, and long-axis views were also achieved. To attempt to reduce foreshortening from the apex, an apical window was achieved that allowed rotation from the apical four-chamber to the two-chamber and long-axis views without apparent shifting of the apex from the center of the echocardiographic sector. CD echocardiography (velocityvariance mode) was performed of the aortic and mitral valves to assess for regurgitation from the parasternal long-axis and apical four-chamber, five-chamber, and longaxis views. Mitral and aortic regurgitation, if present, were graded using previously described methods.6l 7 Echocardiographic analysis. Quantitative analysis of LVF was performed using the analysis system of the Hewlett-Packard echocardiographic machine. The left ventricular endocardial surfaces were digitized using enddiastolic (maximal area) and end-systolic (minimal area) frames to obtain cross-sectional areas at the short-axis mitral valve level (AM) and at the midpapillary muscle level (AP). The leading edge technique, as recommended by Wyatt et al.,8 was used to trace endocardial edges. Ventricular length (L) at end diastole and end systole were measured using a four-chamber view from the apex to the midpoint of an imaginary line at the mitral anulus. Ventricular volume (V) in end diastole and end systole was calculated by the modified Simpson method, where V = (L x AM/3) + ([AM + AP] x L/6) + (L x AP/9).“-‘” Three determinations were averaged and ejection fraction (EF) was calculated in the usual fashion. EF was reproducible within 4 EF units. Transesophageal and transthoracic echocardiograms were analyzed in a blinded fashion by a single investigator. Transthoracic echocardiograms were analyzed in a blinded fashion and in a random sequence. Statistical analysis. Values are mean t- 1 standard deviation. Analysis of variance for repeated measures (Scheffe’s F test) was used to assess differences in EF, heart rate, and blood pressure. Least-squares linear regression

Volume

123

Number

4, Part 1

TEE influence

p=ns I

p
1007

pt0.002

I

I

on LV function

I

I

70.

2

70

g

60.

g

60

i

50.

g

50

$

40.

g

30.

F 0

20.

I

I

---1

80 ;

pto.0

Y tu 10. OJ PRE

DURING

POST

Fig. 1. Alteration in transthoracic echocardiographically-derived left ventricular ejection fraction (LVEF) by transesophageal echocardiography (TEE) in subjects with impaired left ventricular function and sedation (n = 11). Individual (solid lines) and mean (broken line) LVEF of the group are shown before (PRE), before the end of (DURING), and 10 minutes after (POST) TEE.

PRE

DURING

POST

Fig. 2. Alteration in transthoracic echocardiographically-derived left ventricular ejection fraction (LVEF) by transesophageal echocardiography (TEE) in subjects with impaired left ventricular function and no sedation (n = 13). Individual (solid lines) and mean (broken line) LVEF of the group are shown before (PRE), before the end of (DURING), and 10 minutes after (POST) TEE.

analysis was used to assess correlations between transesophageal and transthoracic measures of volume and EF. Spearman’s correlation coefficient (rJ was used to assess correlation between physician-determined versus patientdetermined patient tolerance score. The Wilcoxon signedrank test was used to assess differences in patient tolerance score. A probability value (pl < 0.05 was considered statistically significant.

y=o.9 r = 0.93 SEE

q

6.6%

p < 0.001

RESULTS Influence

104

of TEE on left ventricular function (Table I). Subjects were divided into one of two groups with normal (EF L 55 % ) and abnormal (EF < 55 ‘%) LVF on the basis of EF determined by TTE before TEE. Left ventricular EF derived by TTE significantly increased from 37 + 13% to 45 + 15% (p < 0.001) during and to 41 +- 13% (p < 0.002) 10 minutes after TEE in the group (n = 24) with abnormal function. EF did not change during or after TEE in the normal LVF group (rz = 26). In 13 of 24 subjects in the abnormal group, EF significantly increased during TEE as defined by an increase in EF by at least 5 EF units (Figs. 1 and 2). In four of these subjects, LVF normalized during TEE. Status

of sedation

on the influence

of TEE on LVF

(Table I). A similar increase in EF during TEE was seen in subjects with abnormal LVF who received sedation (n = 11) compared with patients (n = 13) who were not sedated. A significant increase in EF (i.e., an increase in EF by at least 5 EF units) during TEE occurred in 7 of 11 and in 6 of 13 subjects sedated and not sedated, respectively (Figs. 1 and 2). In the normal LVF groups with (n = 15) and without

10

,

,

20 30 Transesophsgeal

, 40

50 ejectton

60

70

fraction

80 fX)

90

Fig. 3. Linear regression analysis of entire group (n = 50) between transthoracic and transesophageal echocardiographically-derived left ventricular ejection fraction.

(n = 11) sedation, EF was unchanged during and after TEE. A mean midazolam dose of 4.0 + 2.7 mg (range 1.0 to 10.0 mg) was used in subjects sedated (n = 26). Comparison

of TTE- and TEE-derived

EF and volumes

(Figs. 3 to 5). No significant differences were found between mean EF (57 f 17 % versus 58 k 17%) p = ns), end-diastolic volume (123 + 55 versus 119 + 50 ml, p = ns), and end-systolic volume (59 -t 52 versus 55 f 46 ml, p = ns) derived by TEE and TTE, respectively, during the procedure. Excellent correlations were found between the two methods of determining EF (r = 0.93), end-diastolic volume (r = 0.95), and end-systolic volume (r = 0.98) (Figs. 3 to 5). Patient tolerance of TEE and hemodynamics. In sub-

1008

Stoddard

et al.

American

100.

r = 0.95 SEE = 15.6

50.

p < 0.001 y

u+. 0

,

.

,

,

TT~beSo:~~ge111’5e0nd-(Hastollc

, 200

=

0.85x

, , 250 volume

ml l

, 300 (ml)

14.2

, 350

Fig. 4. Linear regressionanalysisof entire group (n = 50)

between transthoracic and transesophagealechocardiographically-derived left ventricular end-diastolic volume. 250. 225. 200.

./

175. 150. 125.

Fig. 5. Linear regressionanalysisof entire group (n = 50)

between transthoracic and transesophagealechocardiographically-derived left ventricular end-systolic volume. jects (n = 24) not sedated, the physician-determined and patient-determined patient tolerance scores did not differ (1.2 + 0.8 versus 1.4 k 1.0, respectively; p = ns) and significantly correlated (r, = 0.77, p < 0.001) (Table II). Patient tolerance and mean probe insertion time did not differ among groups (Table III). Heart rate, systolic blood pressure, and diastolic blood pressure did not increase during TEE in any group (Table III). Nineteen patients had no valvular insufficiency and 31 had mitral or aortic regurgitation before TEE. There was no change in the incidence or severity of mitral and aortic insufficiency during and after TEE compared with control levels. DISCUSSION

LVF is an important determinant of survival in many types of acquired heart disease.14-i7The left ventricular EF remains the most common index of systolic performance utilized clinically. In addition, left ventricular volume determination is useful in assessingthe progression of multiple forms of acquired heart disease.‘s, ig Measures of left ventricular EF and volumes are usually deemed most reliable when

April 1992 Heart Journal

they are derived from contrast or radionuclide ventriculography. However, the reliable calculation of left ventricular EF and volumes by transthoracic 2D echocardiography has been demonstrated.g, ll. 13.20-25 TEE is being used to assessglobal LVF. However, little data exist on the accuracy of TEE for this purpose.2-4In the present study, the TEE procedure significantly augmented left ventricular ejection in over 50% (13 of 24) of subjects with impaired LVF. LVF normalized in 17% (4 of 24) of these subjects. Sedation was ineffective in blunting or ameliorating the influence of the TEE procedure on LVF. However, EF did not increase during TEE in the majority of subjects (37 of 50) studied. EF, end-diastolic left ventricular volume, and end-systolic left ventricular volume derived by TEE were comparable with those derived by TTE. Influence of TEE on LVF and hemodynamics. Few studies have examined the potential influence of the TEE procedure on LVF. In 17 patients, Bruere et a1.2 noted slight but significant increases in cardiac output (6 f 10 %#), systolic blood pressure (9 t 13 P;), and heart rate (6 ? 8 % ) 10 minutes after TEE probe insertion, consistent with the induction of a “slight hyperdynamic state.“2 In the present study, heart rate and blood pressure were unchanged 12 to 19 minutes during TEE. However, LVF increased in the group with impaired LVF. The mechanism for the increase in LVF during TEE is unexplained. Nonspecific stimulation of the sympathetic nervous system by the emotional and physical stress of the TEE procedure could potentially explain such an increase in EF. However, this postulate is not supported by the lack of increase in heart rate and blood pressure in the present study. In addition, patient tolerance was no worse in the groups experiencing an enhanced LVF compared with the groups with unchanged LVF. Sedation had no effect on blunting the TEEinduced increase in EF. A change in mitral or aortic valve regurgitation could alter EF, but was not seen in the present study. Correlation

of TEE- and TTE-derived

voiumes

and EF.

In the present study, volumes and EF derived by TEE correlated excellently with those determined by TTE. These results are consistent with the findings of three preliminary studies2-4 that have examined the quantitative accuracy of TEE-derived left ventricular volumes and EF. Bruere et a1.2in 27 subjects showed that the percent fractional area change derived by TEE correlated well with radionuclidedetermined EF (r = 0.92). In a preliminary study, Shakudo et al.,3using the area-length method, showed in 29 patients that good correlations exist between TTE-derived and TEE-derived EF (r = 0.90,

Volume

123

Number

4, Part 1

TEE influence

Table II. Comparison of physician-determined

and patient-determined

P a t i e n t Correlation

s c 0 r e coefficient

Cl+)

Good

score

(2+)

Fair

(3+)

Poor

(4+)

Poor

(4+)

0

0

0

0

Fair

(3+)

1

0

2

1

4

3

1

0

12

0

0

0

Good

(2+)

Well

(l+)

1009

patient tolerance score in subjects not sedated Physician

Well

on LV function

frd = 0.77 (p < 0.001).

Table III. Influence of transesophageal echocardiography (TEE) on hemodynamics and patient tolerance

LVF Abnormal Abnormal Normal Normal

Sedation Yes No Yes No

No. 11 13 15 11

Probe insertion (min)

TS 1.2 1.5 1.7 1.5

1 0.6 ? 1.0

HR Pre

SBP

(beatslmin) During

Post

(mm Hg)

During

Pre

DBP Post

Pre

19 5 5 18 ? 7

84 + 17 85 + 18 82 f 16 147 f 35 146 +- 29 136 f 28 83 +Z 18 85 i 16 83 f 15 125 + 24 124 * 25 124 + 26

1.0

17 k 6

86

+ 0.8

12 + 3

84 ? 21 84 f 22 77 * 19 139 f 21 136 t 32 139 & 23

k

2 16

89 k 14

84

-r- 16

140

+ 22

129

t

21

118

f

16*

We thank manuscript

Karen House preparation.

and Sharon

Hg)

During

Post

75 + 16 78 k 14 71 + 11 67 + 15 71 + 17 68 k 14 76 4 10

72 -e 11

65

t

8t

77 t 16 71 & 17 65 f 11

TS, Physician-determined patient tolerance score; LVF, left ventricular function; HR, heart rate; SW’, DEP, systolic and diastolic tively; Pre, During, Post, before, during, and 10 minutes after TEE, respectively. *p < 0.01 versus pre SBP; tp < 0.01 versus pre DBP. There was no significant difference among the four groups in tolerance score

SEE = 5.6%), end-systolic volume (r = 0.89, SEE = 12.0 ml), and end-diastolic volume (r = 0.87, SEE = 15.8 ml). Bashein et a1.,4 using an experimental endoscopic micromanipulator, demonstrated in 10 dogs the ability to three-dimensionally reconstruct the left ventricle and accurately derive stroke volume. Regional wall motion abnormalities could potentially complicate the derivation of EF by 2D echocardiography. However, a recent study by Albin et a1.25 has demonstrated that 2D TTE compared with radionuclide ventriculography can accurately assess left ventricular EF in patients with regional wall motion abnormalities. The appropriate algorithm to derive EF by TEE in the setting of regional wall motion abnormalities is yet to be determined. Regional wall motion abnormalities may affect the accuracy of the method used in the present study. Clinical implications. TEE can be used to derive EF in subjects with normal LVF or global hypokinesis. However, physicians performing the TEE procedure to assess LVF should be aware of its affect on LVF, particularly in subjects with mild global left ventricular hypokinesis, where LVF may appear normal during the procedure.

(mm

blood

pressure,

or probe

McGregor

insertion

for their

respectime,

help in

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