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Episodic Monoplane Transesophageal Echocardiography Impacts Postoperative

Management of the Cardiac Surgery Patient

Simon Maltais, MD, PhD,* William T. Costello, MD, Frederic T. Billings IV, MD, MSc, Julian S. Bick, MD,

John G. Byrne, MD,* Rashid M. Ahmad, MD,* and Chad E. Wagner, MD

Objective: A new slender, flexible, and miniaturized dis-

posable monoplane transesophageal TEE probe has beenapproved for episodic hemodynamic transesophageal echo-

cardiographic monitoring. The authors hypothesized that

episodic monoplane TEE with a limited examination would

help guide the postoperative management of high-risk

cardiac surgery patients.

Design: The authors analyzed the initial consecutive

observational experience with the miniaturized transeso-

phageal echocardiography monitoring system (ClariTEE,

ImaCor, Uniondale, New York).

Setting: Single institution in a university setting.

Participants: Unstable cardiac surgery patients.

Interventions: The authors assessed fluid responsiveness,

echocardiographic data, and concordance among hemo-

dynamic data.

Measurements and Main Results: From June 2010 to

February 2011, 21 unstable cardiac surgery patients with

postoperative instability were identified. Two patients (10%)

required reoperation for bleeding and tamponade physiol-ogy. Right ventricular dysfunction was diagnosed by episo-

dic TEE monitoring in 7 patients (33%), while hypovolemia

was documented in 12 patients (57%). Volume responsive-

ness was documented in 11 patients. In this observational

study, discordance between hemodynamic monitoring and

episodic TEE was qualitatively observed in 14 patients (66%).

Conclusion: The authors demonstrated the ability of

episodic monoplane TEE to identify discordance between

hemodynamic monitoring to better define clinical scenarios

in unstable cardiac surgery patients. For these challenging

patients, limited episodic TEE assessment has become a

cornerstone of ICU care in this institution.

& 2013 Elsevier Inc. All rights reserved.

KEY WORDS: cardiac surgery, transesophageal echocardio-

graphy, hemodynamic monitoring

MULTIPLANE TRANSESOPHAGEAL echocardiogra-phy (TEE) is used intraoperatively during most cardiacsurgical procedures.1 TEE is used to quantify myocardial

dysfunction, identify valvular abnormalities, and confirm place-

ment of cannulae for patients implanted with a left ventricular

assist device (LVAD).210 Transthoracic echocardiography is

becoming increasingly useful in the diagnosis and management

of the critically ill, but its use can be limited in the immediate

postoperative cardiac surgery patient.1113 Extending the use of

traditional multiplane TEE probes can be difficult secondary to

the expense in allocating machines, probes, sterilization

requirements, large probe diameter, and its inability to be left

in place for an extended period of time.1416

A new slender, flexible, and miniaturized disposable trans-

esophageal TEE probe has been approved by the United States

Food and Drug Administration to remain in situ for 72 hours,

enabling episodic hemodynamic monitoring.17 The probes pro-

vide the opportunity to perform frequent direct qualitative and

semi-quantitative assessment of myocardial function and filling

in the setting of rapidly changing conditions common to the post-

operative cardiac surgery patient. Though several case studies

have shown examples of the utility of monoplane TEE and

episodic monitoring, no larger studies have defined which groups

of patients could benefit from this technology.1719

The authorscardiovascular intensive care unit (CVICU) has placed more than

200 miniaturized monoplane probes in postoperative cardiac

surgery patients, and, therefore, this institution is in the position

of having substantial experience with this new technology.

The authors hypothesized that episodic monoplane TEE

guides assessment of intravascular/myocardial volume, ino-

trope need, vasopressor use, and assessment of pericardial

effusions in critically ill cardiac surgery patients.

METHODS

Institutional review board approval was obtained with an exception

granted for obtaining study-specific consent secondary to the policy

that entry criteria in the study follow the clinical CVICU protocol for

monoplane TEE evaluation.

This study was a prospectively enrolled descriptive case series of

unstable cardiac surgery patients and included the institutions consec-

utive experience with the miniaturized transesophageal echocardio-

graphy monitoring system in cardiac surgery patients (ClariTEE,

ImaCor, Uniondale, NY).

All cardiac surgery patients at this institution have an intraoperative

TEE unless contraindicated. All patients received a pulmonary artery

catheter intraoperatively. Patients received a monoplane TEE if they

became hemodynamically unstable at any time in the ICU, defined as

persistent systolic BP o100 mmHg, cardiac indexo2.2 L/min/m2,

SvO2o 60%, suspected pericardial effusion with tamponade physiol-

ogy, base deficit48 mEq/L, or lactate45 mg/dL despite persistent

inotropic, vasopressor, and/or volume resuscitation, and concern for or

known right ventricular failure. Right ventricular (RV) failure was

defined by a combination of features, including elevation in central

venous pressure (418 mmHg), a normal or lower pulmonary capillary

wedge pressure caused by poor left atrial filling, a diminished cardiac

index (o2 L/min/m2), assessed with right-sided thermodilution techni-

ques, a newly decreased or changed right ventricular function (free wall

assessment in the ME4chx/TgSax,o2 cm tricuspid annular plane

excursion) by the echo examination, and an associated dilated right

ventricle.2022 Volume responsiveness was assessed in all patients.

Qualitative assessment such as kissing papillary muscles in the TgSax

view were used to assess, quantitatively, an LVEDA measured in the

From the *Division of Cardiovascular Surgery; and yDivision of

Anesthesiology and Critical Care, Vanderbilt Heart, Vanderbilt Uni-

versity Medical Center, Nashville, Tennessee.$Drs. Bick, Costello, and Wagner taught echocardiography work-

shops for ImaCor Inc. in 2012.

Address reprint requests to Chad E Wagner, MD, Division of Anes-

thesiology, Vanderbilt Heart, 1215 21st Avenue South MCE 5th Floor,

Nashville, TN 37232-8808. E-mail: chad.e.wagner@vanderbilt.edu

& 2013 Elsevier Inc. All rights reserved.

1053-0770/2605-0031$36.00/0

http://dx.doi.org/10.1053/j.jvca.2013.02.012

Journal of Cardiothoracic and Vascular Anesthesia, Vol 27, No 4 (August), 2013: pp 665669 665

mailto:chad.e.wagner@vanderbilt.edumailto:chad.e.wagner@vanderbilt.edumailto:chad.e.wagner@vanderbilt.edumailto:chad.e.wagner@vanderbilt.edumailto:chad.e.wagner@vanderbilt.edumailto:chad.e.wagner@vanderbilt.eduhttp://localhost/var/www/apps/conversion/tmp/scratch_14/dx.doi.org/10.1053/j.jvca.2013.02.012http://localhost/var/www/apps/conversion/tmp/scratch_14/dx.doi.org/10.1053/j.jvca.2013.02.012mailto:chad.e.wagner@vanderbilt.edumailto:chad.e.wagner@vanderbilt.edumailto:chad.e.wagner@vanderbilt.edu

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TgSax view less than 12 cm2 and/or an increase in LVEDA greater than

2 cm2 after performing passive leg raise maneuvers with a RASS 3

were considered to be potentially volume responsive.2325

The authors systematically performed a monoplane TEE imaging

session every 2-3 hours for the initial 6 hours post-enrollment and as

needed until the patient reached hemodynamic stability or reached 72

hours after surgery. The 72-hour cut-off was determined by a safetymechanism built into the software of the device to prevent long-term

intubation and perceived infection risk (http://imacorinc.com). Imaging

sessions were performed by 4 board-certified or -eligible anesthesiolo-

gists on service in the ICU and 1 anesthesia critical care fellow who

received 2 months of education and oversight before being allowed to

clip images. The fellows examinations always were reviewed quickly

by the attending intensivist. The authors sought to obtain the mid-

esophageal four-chamber (ME4C) and transgastric short-axis (TGSAX)

views to assess left ventricular end-diastolic area (LVEDA), left ventri-

cular fractional area change (LVFAC), right ventricular function,

intravascular volume status and associated qualitative response to fluid

resuscitation, and pericardial effusion with tamponade physiology.

Hemodynamic discordance was defined as the point at which the

echocardiography examination findings convinced the intensivist to

change management direction from what was thought before the

echocardiography imaging session.

The examiner systematically collected bedside echo information.

Echocardiographers were not blinded to other available hemodynamic

monitors. For all patients, the echocardiographer recorded whether

information obtained during imaging sessions influenced hemodynamic

management. Additional hemodynamic data were recorded by the

bedside nurse and collected from the electronic medical record.

Descriptive statistics for categoric variables are reported as frequency

and percentage, and continuous variables are reported as mean (stand-

ard deviation) or median (range) as appropriate.

RESULTS

Between June 2010 and February 2011, the authors

performed episodic monoplane TEE in 20 cardiac surgery

patients with postoperative instability and 1 patient with mitral

valve endocarditis who arrived in septic shock for surgical

evaluation. Episodic echocardiographic studies were completed

in all of the 21 patients and discontinued when patients reached

hemodynamic stability or 72 hours after intervention. Patients,

interventions, and hemodynamic findings are detailed in

Table 1.A total of 512 loops were recorded from imaging sessions

involving 21 unstable cardiac surgery patients. The average

number of imaging sessions was 3.28, while the median was 3

per patient. Within this group, 2 patients (10%) required

reoperation for bleeding and tamponade physiology. The

average ICU length of stay was 8.8 6.9 days, and the

observed in-hospital or 30-day mortality was 14%. Both the

ME4C and TGSAX views were obtained for 96% of patients.

Mean LVEDA was 17.1 6.3 cm2, while average LVFAC

was 48.7% 16.6%. Right ventricular dysfunction was

diagnosed by episodic TEE monitoring in 7 patients (33%).

Hypovolemia was documented in 12 patients (57%) (Fig 1).

Volume responsiveness was documented in 11 patients.

Figure 1 summarizes fluid management interventions for these

patients. The group that was determined to be volume respon-

sive (n 11) by echocardiography was 826 mL (1597 mL)

net fluid positive over the subsequent 6 hours compared to

78 mL (405 mL) in the same period in the group not

determined to be volume responsive (p 0.013). In this

observational study, discordance between standard hemody-

namic monitoring and episodic limited TEE was observed

qualitatively in 14 patients (66%).

DISCUSSION

In this case series, key areas for which direct visualization

added more information than achieved from clinical assessment

and hemodynamic monitors included hypovolemia despite high

filling pressures, assessment of RV function, biventricular

Table 1. Hemodynamic Data of Subjects

Patients

n 21

Apache

score Intervention CVPXPAPs-PAPdXCI Major TEE findings Discordance

1 25 AVR 9X45-26X1.9 Tamponade yes

2 24 MVR/CAB 8X37-20X1.5 Hypovolemia no

3 20 RAA 10X42-22X3.2 Hypovolemia yes

4 27 AVR 20X45-23X3.3 Hypovolemia yes

5 24 MVR 12X48-20X2.9 Hypovolemia no

6 22 CABG 9X23-14X1.34 Hypovolemia no

7 22 Pulmonary endarterectomy 16X40-23X3.1 Hypovolemia yes

8 32 Pulmonary embolectomy 16X28-20X1.74 Hypovolemia yes9 20 CABG 12X32-21X3 Hypovolemia yes

10 31 MVR-TVR ND RV dysfunction NXA

11 20 Type-A dissection repair 16X45-28X1.45 Hypovolemia yes

12 27 Double-lung transplant 15X40-24X3.46 RV dysfunction no

13 30 MVR-TV repair 12XND RV dysfunction yes

14 28 CABG 15X52-43X1.89 Tamponade yes

15 24 Cardiogenic shock/ECMO 4X36-18X4 RV dysfunction yes

16 27 Mitral regurgitation/endocarditis/sepsis 16XND Hypovolemia yes

17 27 AVR/CAB 4X27-12X2.6 RV dysfunction yes

18 29 CABG 15XND Hypovolemia no

19 25 Double-lung transplant 9X24-13X2.08 RV dysfunction yes

20 22 AVR/MVR 14X27-15X2.24 RV dysfunction no

21 29 Pulmonary embolectomy 17X27-23X3.32 Hypovolemia yes

MALTAIS ET AL666

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filling in the presence of RV failure, pericardial effusion/

tamponade, myocardial recovery, and weaning from mechan-

ical ventricular support.

Management of cardiac surgery patients in the ICU is

challenging given that intravascular volume, pericardial fluid

collections, and myocardial function are often dynamic processes.

Standard hemodynamic monitoring using CVP, left-sided fill-

ing pressures, and calculated cardiac index frequently are not

predictive of the need for intravascular resuscitation.2628 These

results confirm these findings as the authors observed discord-

ance between hemodynamic monitoring and TEE observations

in 14 patients (66%). Despite filling pressure data, patientsconsidered to be fluid responsive by echocardiography were

more likely to be appropriately resuscitated 6 hours after

initiation of imaging (Fig 2). This study did not correlate fluid

response and resuscitation to patient outcomes. The validity of

LVEDA as a surrogate for fluid responsiveness has been

studied in other works.23,29 Pulse-pressure variation also could

have been used, but this method can be difficult to interpret in

the postoperative cardiac surgery population secondary to a

high incidence of arrhythmias/pacing, RV dysfunction, peri-

cardial effusion/tamponade, and lack of paralysis with sponta-

neous breathing. The impact of episodic monoplane TEE in the

cardiac surgery ICU upon patient outcomes is yet to be

determined; however, in the authors clinical experience,

episodic monoplane TEE monitoring did help elucidate phys-iologic derangement and guide therapy. More importantly,

episodic assessment of changes in fluid status, fluid responsive-

ness, or ventricular size provided clinical guidance in assessing

the timing of fluid resuscitation.

CVP has been shown to be a poor surrogate of RV function,

especially in the acute postoperative setting.30 A number of

factors, including tricuspid regurgitation, level of sedation, or

line calibration potentially can alter the observed CVP value

and subsequently influence treatment. In the current high-risk

cardiac surgery group, the authors observed little CVP variation

during episodes of acute postoperative instability as defined in

the Methods section. In fact, only 2 patients (8%) had a

significant rise in CVP coincident with RV failure. In contrast,

episodic observations found RV failure in 7 patients (33%).

Episodic monoplane TEE monitoring allows direct semi-

quantitative assessment of acute myocardial function changes.

Stunned myocardium undergoes recovery over time that easily

can be visualized by echocardiography. Cardiac index is a poorsurrogate for myocardial recovery and, if used alone in clinical

decision-making, can leave the clinician flying blind. The

authors easily can extrapolate this use to weaning balloon pumps

and other modes of temporary mechanical support. In 2 cases,

return to the OR was guided by episodic monitoring. Monitoring

and diagnosing the evolution of diastolic collapse of the LA, RA,

and, possibly, RV is a key advantage of episodic echocardio-

graphy. The key difference between diagnostic echocardiography

and episodic echocardiography is that with diagnostic echocar-

diography a problem (tamponade) may be diagnosed but the

development of an effusion over time may be missed. The

authors refer to it as the AH-HA moment. Sometimes this

occurs on probe placement, but other times it could be hours to

days (especially in mechanical device management).

Furthermore, much of the information in a diagnostic

echocardiographic exam such as spectral Doppler interrogation

of valves, diastolic dysfunction, detailed two-dimensional valve

interrogation, and color-flow Doppler valve assessment are

redundant given preprocedure studies and postprocedure intra-

operative TEE. Using episodic monoplane TEE does not

preclude obtaining a full multiplane TEE examination if it is

believed by the intensivist or surgeon to be indicated.

While the cost of these probes is not insignificant, this group of

ill patients already has had a significant financial investment in

their initial surgery, and if they are unstable, clinicians are making

decisions (such as return to the operating room) that have profound

clinical and financial implications. At this stage in the ICU, themonoplane TEE examination is performed as an adjunct monitor

to the pulmonary artery catheter, and in the clinical practice, the

data are used in conjunction with other clinical inputs. Decisions to

treat are not solely made by echocardiography (for example, just

because the patient might be fluid responsive does not mean the

Fig 2. Net fluid balance 6 hours after initial TEE exam, separated

into subjects judged responsive and unresponsive to a fluid bolus.

Fig 1. TEE identified pathology in unstable post cardiac surgery

patients.

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authors would give fluid). Clinicians must not forget that this

monitor is episodic and not continuous, and, therefore, as

clinicians, it must be established when to image and be able to

do so 24 hours a day.

Education for this type of technology is in development at

many institutions. The question of how to categorize thelimited examination is being debated on the national stage.

Does an intensivist have to be board certified in perioperative

echocardiography to perform a limited episodic monoplane

TEE exam? Half of the institutions CVICU intensivist faculty

are board certified perioperative echocardiographers; the other

half are not. The authors have held workshops for faculty and

fellows on monoplane TEE, and local experts have been

available to mentor and oversee/over-read exams. The medical

director of the CVICU assesses competency. After 3 years, all

faculty working in the CVICU are competent to perform

monoplane TEE. In the CVICU, there are 18 hours of in-

house attending coverage, and the call attending has the

expectation to continue episodic examinations overnight if

clinically indicated. While the debate rages on the national

stage, it is important to appreciate the complexity of post-

operative cardiac surgery patients, and echocardiography of this

patient population requires substantive knowledge that cannot

be gained in 1-2 courses or 1-2 months.

Limitations

This was an observational nonblinded case series, which

leaves the results open to observer bias. This probe allowed a

semi-quantitative postoperative evaluation and should not

replace standard formal TEE when indicated. Thus, the persons

performing this examination and the cardiac surgeons must

have profound knowledge of the limitations of monoplane

echocardiography to know what abnormalities might be missed

by not performing a complete examination. This study was not

designed to provide outcome data, but rather to elucidate the

impact of episodic monoplane TEE on patient management. No

study has ever proven that any monitoring device can improveclinical outcome. Future work assessing impact of fluid

responsiveness as seen by echo on outcomes will be extremely

important.

While the safety profile has not been published, the probe is

the size of a nasogastric tube with 5 cm of very flexible tip,

which would lead to the belief it would be safer than a

conventional probe. The authors have used more than 200

probes in the CVICU and more than 50 elsewhere with no

complications to date. As the rate of complications is low with

a standard TEE, it will obviously take a larger cohort of

patients to define the safety profile.

CONCLUSION

The miniaturized monoplane disposable probe is specifically

designed for easy assessment of myocardial function and filling

in the critically ill. In this study, the authors demonstrated its

ability to change the clinical management of unstable cardiac

surgery patients. On the basis of these observations, hemody-

namic monoplane TEE assessment has become a useful adjunct

in this institution, extending the hemodynamic assessment

capabilities of TEE from the operating room to the ICU.

Randomized clinical trials are needed to assess the impact of

episodic TEE monitoring on postoperative morbidity and

mortality.

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