Echocardiography provides real-time images of the beatingheart and can help guide thera-

peutic interventions. There are 2 majortechniques available to image the heartwith ultrasound: transthoracic echocar-diography (TTE) and transesophagealechocardiography (TEE). In critical

care, TTE has more limited applica-tions. During mechanical ventilation,lung inflation and its position betweenthe heart and the chest wall causes lossof imaging. TEE, however, providesclear and easily accessible pictures ofthe heart and mediastinal contentsthrough the esophagus and the stom-

ach. It is fast becoming an essential toolin critical care, trauma and in some in-traoperative settings. It provides fast,noninvasive assessment of heart func-tion and structure that is complemen-tary and sometimes superior to invasivemonitoring. It is an ideal monitoringtool since the probe can be left in situ

Trauma and Critical CareTraumatologie et soins critiques

TRANSESOPHAGEAL ECHOCARDIOGRAPHIC ASSESSMENTIN TRAUMA AND CRITICAL CARE

Claude Tousignant, MD

Section Editor: Dr. Donna I. McRitchie

From the Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ont.

Accepted for publication Apr. 2, 1999.

Correspondence to: Dr. Claude Tousignant, Assistant Professor, Department of Anesthesia, St. Michael’s Hospital, 30 Bond St., Toronto ON M5B 1W8

© 1999 Canadian Medical Association (text and abstract/résumé)

Cardiac ultrasonography, in particular transesophageal echocardiography (TEE) provides high-quality real-time images of the beating heart and mediastinal structures. The addition of Doppler technology intro-duces a qualitative and quantitative assessment of blood flow in the heart and vascular structures. Becauseof its ease of insertion and ready accessibility, TEE has become an important tool in the routine manage-ment of critically ill patients, as a monitor in certain operative settings and in the aortic and cardiac evalua-tion of trauma patients. The rapid assessment of cardiac preload, contractility and valve function are invalu-able in patients with acute hemodynamic decompensation in the intensive care unit as well as in theoperating room. Because of its ease and portability, the TEE assessment of traumatic aortic injury afterblunt chest trauma can be rapidly undertaken even in patients undergoing life-saving procedures. The roleof TEE in the surgical and critical care setting will no doubt increase as more people become aware of itspotential.

L’échographie cardiaque, et en particulier l’échocardiographie transœsophagienne, produit des images degrande qualité et en temps réel du cœur battant et des structures du médiastin. La technologie Dopplerpermet d’évaluer aussi qualitativement et quantitativement la circulation sanguine dans le cœur et les struc-tures vasculaires. Parce qu’elle est facile à mettre en place et facile d’accès, l’échographie transœsophagi-enne est devenue un outil important dans le traitement routinier de patients en état critique, comme moyende contrôle dans certains contextes opératoires et dans l’évaluation de l’état aortique et cardiaque de pa-tients traumatisés. L’évaluation rapide de la précharge cardiaque, de la contractilité et du fonctionnementdes valvules est précieuse chez les patients victimes d’une décompensation hémodynamique aiguë aux soinsintensifs, ainsi qu’à la salle d’opération. Comme elle est facile à utiliser et portable, l’échographie transœ-sophagienne d’évaluation de traumatismes à l’aorte consécutifs à un traumatisme contondant au thoraxpeut être réalisée rapidement, alors même qu’un patient subit une intervention destinée à lui sauver la vie.L’utilisation de l’échocardiographie transœsophagienne dans des contextes de chirurgie et de soins cri-tiques augmentera certainement à mesure que l’on en connaîtra mieux les possibilités.

CJS, Vol. 42, No. 3, June 1999 171

during operative interventions with noloss of image. Several studies havedemonstrated a role for TEE in criticalcare.1–5 In one study, the treatment waschanged in 44% of patients with a pul-monary artery catheter (PAC) in situ asa result of the TEE examination.3 Like-wise, in another study, TEE examina-tion resulted in a change of treatmentin 62% of patients.4 In critically ill pa-tients who were deemed euvolemic byPAC examination, TEE indicated that45% were not. Indeed, 36% of these pa-tients were found to be hypovolemicand 9% were hypervolemic. TEE sup-ported the finding by PAC examina-tion of normal left ventricular functionin only 61% of critically ill patients; theremaining 39% showed hypocontractil-ity on TEE. Therefore, TEE wouldseem to complement, if not add to, theusual hemodynamic monitoring of crit-ically ill patients.TEE need not be limited to the

heart. An examination of the ascend-ing and descending aorta can be un-dertaken to evaluate dissections andtraumatic disruptions or to assess theseverity of vascular disease or dysfunc-tion. Furthermore, both the left and

right pleural spaces can be visualizedwhen looking for effusions. Para-aorticmasses and consolidated lung can alsobe identified. In the operating room,TEE can be used as a continuous mon-itor to evaluate ventricular size andcontractility. Changes in size may rep-resent acute preload changes whereasloss of contractility in a particular wallusually represents ischemia.

STANDARD IMAGING USINGECHO

The standard images obtained withthe TEE probe positioned in theesophagus are the 4- and 5-chamberviews. The 4-chamber view includesthe left atrium, the left ventricle, theright ventricle and the right atrium.The 5-chamber view is obtained bypulling the probe up slightly to includethe left ventricular outflow tract(LVOT). This position will provideclear pictures of the aortic valve, andwhile rotating the angle of interroga-tion approximately 40° a cross-sectionof the aortic valve including the coro-nary arteries can be seen. Further rota-tion will show a longitudinal section of

the ascending aorta, aortic valve andLVOT. It is not possible to image thedistal segment of the ascending aortaand the arch as the left main-stembronchus blocks these structures. Inthe 5-chamber view, the mitral valve,left upper pulmonary vein, left atrialappendage, tricuspid valve and intera-trial septum can also be evaluated (Fig.1). The descending aorta can be im-aged from the arch to the diaphragmby rotating the probe to the left. Boththe right and left pleural spaces alongthe mediastinum can also be imaged.Pleural effusions can be seen as well asconsolidated or collapsed lung.The probe can be pushed down fur-

ther into the stomach and flexed supe-riorly to abut the superior aspect of thestomach and the inferior aspect of thediaphragm. The heart’s inferior wallsits on the left hemidiaphragm, provid-ing an excellent opportunity to obtaincross-sections of the left ventricle.

Indications and contraindications

Contraindications to TEE includeesophageal or gastric disease. Indeed,gastric perforation has been noted af-

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172 JCC, Vol. 42, No 3, juin 1999

FIG. 1. The 5-chamber view is demonstrated on the left. The image on the right demonstrates the transgastric short-axis view of the left ventricle. The en-docardium of the left ventricle has been traced to obtain surface area by planimetry.

ter intraoperative TEE.6 Patients witha history of gastric ulcer, esophagitisor gastrectomy can undergo TEE aslong as the disease is not active or thesurgery is not recent. Proven hiatushernia can make insertion of the probedifficult. Liver cirrhosis severe enoughto cause esophageal varices can lead tobleeding on insertion. Probe insertionmay require neck manipulation, whichmay have consequences in patientswith disease or injury to the cervicalspine. In severe cervical spine disease,the strong angulation of the cervicalspine may make insertion difficult.Furthermore, constant pressure by theprobe on the posterior pharynx maycause ulcers or necrosis.The indications for performing

TEE are shown in Table I.

HEMODYNAMIC ASSESSMENT

TEE has become an invaluable toolin the assessment of acute hemody-namic decompensation in critical careand in the operating room. The mostcommon causes include loss of myo -cardial contractility, hypovolemiaand acute valvular disease. It is alsouseful in routine hemodynamic work-up. Assessment of cardiovascular func-tion by TEE can be divided into 3 ma-jor parts: preload, contractility andvalve function.

Preload

In ventilated critically ill patients,pulmonary capillary wedge pressuresmay not accurately reflect the volumestatus of the patient because ventricu-lar compliance and ventilatory para-meters may influence this pressure.The left ventricular end-diastolic area(EDA) and end-systolic area (ESA) inthe transgastric midpapillary short axisview can provide a rapid estimate of apatient’s volume status. These leftventricular areas can be rapidly calcu-lated by planimetry of the endocardialborder (Fig. 1, right).Patients who have graded volume

loss will initially demonstrate a decreasein EDA as well as ESA.2,7,8 Further de-creases result in “kissing” or touchingof the papillary muscles in systole.Large volume losses result in oblitera-tion of the left ventricular cavity in sys-tole. Other disorders, however, maygive similar findings. In septic shock,for example, a profound depression ofsystemic vascular resistance results incomplete emptying of the left ventriclein systole. An understanding of the pa-tient’s underlying pathophysiology isessential for appropriate interpretation.Patients with abnormal left ventricularfunction present special problems.These patients will have a chronicallydilated left ventricle and may demon-strate hypovolemia at higher left ven-tricular sizes than patients with pre-existing normal left ventricular func-tion. Inferring optimal left ventriclesize becomes more difficult.

Contractility

TEE provides various ways inwhich left ventricular systolic functioncan be assessed. An accurate assess-ment, however, is complicated by thefact that most available methods areload sensitive and are one-beat mea-sures of contractility. Most of the time

a qualitative assessment is performedto estimate ventricular contractility.However, some simple and fast mea-surements are possible using TEE.The fractional area of contraction, anestimate of ejection fraction is the dif-ference in left ventricular surface areasin the midpapillary transgastric shortaxis view during a single cardiac cycle.This measurement has some limita-tions, but it can provide a reasonableglobal estimate of left ventricular func-tion.9,10 The corrected velocity of cir-cumferential fibre shortening is said tobe more preload independent; how-ever, it is cumbersome and time-consuming to calculate.11,12 Finally,cardiac output can be calculated byDoppler technology which allowsmeasurement of forward flow throughthe aortic valve.During myocardial ischemia or af-

ter myocardial infarction, the myocar-dial territory involved will stop con-tracting. TEE is very sensitive indetecting these changes, but certainlimitations can make some assessmentsdifficult. Assessment of wall motion ismostly subjective. Severity is gradedfrom no wall motion abnormality(normal) to akinesis or even dyskine-sis. The appearance of a normally con-tracting wall on TEE is that of motionand thickening. It takes a certain de-gree of experience to accurately assesswall motion abnormalities.

Valve assessment

Examination of the heart valves is anintegral part of the hemodynamic as-sessment. Valve abnormalities found onechocardiography may be instrumentalin defining a cause for hemodynamicdecompensation. Valve assessment forincompetence or stenosis requires ahigh degree of skill and a thoroughknowledge of Doppler echocardiogra-phy. A morphologic assessment of themitral, aortic and tricuspid valves is usu-

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CJS, Vol. 42, No. 3, June 1999 173

Table I

Thrombi, source of embolism

Indications for the Use of TransesophagealEchocardiography (TEE)

Acute hemodynamic decompensation

Vascular volume

Left and right ventricular function

Valve disease

Pericardial effusion, tamponade

Traumatic injuries

Dissection

Endocarditis

ally performed first. The pulmonaryvalve is often obscured and cannot beimaged adequately. It is important tonote structural changes such as thicken-ing (myxomatous degeneration), calci-fication, disruptions, flail segments,range of motion and tumours or vege-tations. Colour Doppler is used to as-sess incompetence and readily demon-strates jet size and direction. Doppler isused to assess valvular areas.

CARDIAC TAMPONADE

Cardiac tamponade is readily as-sessed by TEE (Fig. 2). Classic echosigns of tamponade include a fluid col-lection surrounding the heart, com-pression of cardiac chambers includingdiastolic collapse and septal shift intothe left ventricle. In some circum-stances, echo signs of cardiac tampon-ade can be very subtle or absent. Largefluid collections need not be present.In trauma or cardiac surgery, clots canalso be observed compressing the rightatrium, the right ventricle and occa-sionally the left atrium. Although theseclots may be small, their hemodynamicconsequence can be profound.

TRAUMATIC AORTIC INJURY

The method of choice for evaluat-ing traumatic aortic injury remains an-

giography. The presence of a widenedmediastinum on the chest radiographin patients who have suffered bluntchest trauma, often leads to angiogra-phy. There is, however, a poor predic-tive value to the chest radiograph di-agnosis of traumatic aortic injury thatfrequently leads to unnecessary an-giography.13,14 Angiography requiresthe transport of a sometimes hemody-namically unstable patient to a special-ized area. The procedure requires onaverage 70 minutes to perform andmay delay definitive therapy of otherserious injuries.15 TEE of traumaticaortic injury, on the other hand, canbe performed safely and rapidly(within 10 minutes) at the bedside inthe operating room, the emergencyroom or the intensive care unit.Acute deceleration injuries usually

result in aortic disruption at the as-cending aorta or more commonly atthe descending aorta 2 to 3 cm distalto the origin of the left subclavianartery. Rarely will the aortic arch beinvolved. TEE is capable of imagingthe ascending and descending aortawith ease. The aortic arch, however,cannot be visualized.Recent studies have demonstrated

a 75% specificity and a 100% sensitiv-ity for TEE in the diagnosis of medi-astinal hematomas.14 Echo signs in-clude an increased distance betweenthe TEE probe and the aorta (morethan 3 mm), a double contour aspectof the aortic wall and ultrasound sig-nals between the aorta and the visceralpleura. A mediastinal hematoma,however, does not always imply aorticinjury because blood accumulationcould be the result of injuries to bonystructures or other vessels. Traumaticaortic injury can result in intimal tearswith or without dissection. There canalso be aortic disruption with falseaneurysm formation or transection.Complications of traumatic aortic in-jury include pericardial tamponade

and valvular disruption. All of theseare readily identified by TEE.TEE is very sensitive in examining

the intimal surface of the aorta. In-deed, a small intimal disruption thatmay not be visible on angiography canbe seen on TEE. In one study exam-ining aortic dissections, a lower sensi-tivity for aortography than TEE wasfound because the angiogram couldnot identify noncommunicating inti-mal tears.16 Signs of aortic injury onTEE with dissection or disruption in-clude: turbulent flow by colourDoppler, dissection flaps, spontaneousecho contrast in the aorta (whenblood flow is very low, there is an ap-pearance of “smoke” in a vessel),thrombus or aneurysm.In many institutions, TEE has be-

come the modality of choice for evalu-ating traumatic aortic injury. It is quickand can be readily performed in variousenvironments while other lifesavingprocedures are under way. It is sensitivein identifying mediastinal hematomasfrom any cause, aortic intramural in-juries and intimal disruptions, whichcan be missed by angiography. Aortog-raphy may still be required when the di-agnosis is unclear or when there is aneed to examine structures that cannotbe seen by TEE, such as the coronaryarteries, the aortic arch or other vesselssupplying vital organs.Because of its ready accessibility

and ease of transportation, the role ofTEE in trauma and critical care and inthe operating room continues to in-crease. It is an invaluable tool in ex-amining cardiac and other mediastinalstructures as well as being able torapidly assess cardiac function. It hasgained an increasing role in the assess-ment of acute hemodynamic decom-pensation, in aortic evaluation and forintraoperative monitoring. As morepeople become familiar with TEE, itsrole will no doubt increase in mosthospital settings.

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174 JCC, Vol. 42, No 3, juin 1999

FIG. 2. An example of pericardial effusion in thetransgastric short-axis view.

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Section Editor’s comment: As can beseen from Dr. Tousignant’s report,the role of echocardiography is dra-matically expanding. In addition toits familiar role in the diagnosis ofblunt aortic injury, I have found ittremendously helpful in the inten-sive care unit setting in dealingwith difficult hemodynamic issues.When colleagues have a keen inter-est in using this tool in varied set-tings, access improves, indicationswiden and relax, and the clinical in-formation provided is pertinent,precise and targeted to specific clin-ical questions. I would suggest thatthe support of individuals havingsuch an interest may lead to morerational patient care as they gainadded familiarity with the use ofechocardiography in this setting.