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Adult Perioperative Echocardiography: Anatomy,

Mechanisms and Effective Communication

Hector I. Michelenaa,⁎, Rakesh M. Surib, Joseph Malouf a,Maurice Enriquez-Saranoa, Sunil V. Mankada

aDivision of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USAbDivision of Cardiovascular Surgery, Mayo Clinic, Rochester, MN, USA

A R T I C L E I N F O

Statement of Conflict of Interest: None.⁎ Address reprint requests to Hector I. MichE-mail address: michelena.hector@mayo.

http://dx.doi.org/10.1016/j.pcad.2014.05.0040033-0620/© 2014 Elsevier Inc. All rights rese

A B S T R A C T

Keywords:

Intra-operative transesophageal echocardiography (TEE) is a mature imaging technique whichrepresents the premier surgical quality control instrument in the contemporary operatingroom. In adult cardiac surgery, management of valvular heart disease and related structuralcardiac abnormalities derive the most benefit from perioperative echocardiography whichincludes pre-operative transthoracic echocardiography, intra-operative TEE and post-surgicalechocardiographic surveillance. This review discusses the theoretical background upon whichthese imaging techniques are built-on, and offers a practical state-of-the-art guide on theirapplication, emphasizing the importance of anatomic relationships, mechanisms of dysfunc-tion and effective communication with our surgeons.

© 2014 Elsevier Inc. All rights reserved.

Intra-operativeTransesophageal echocardiographyMitral valveAortic valveHypertrophic cardiomyopathy

Background and critical principles

The concept of transesophageal echocardiography (TEE)emerged in 19761 as a solution to cardiac imaging in patientswith poor transthoracic echocardiogram (TTE) acoustic win-dows. However Frazin et al.1 could not have predicted thatTEE, by virtue of not intruding into the surgical sterile field,would allow real-time cardiac imaging during cardiac surgeryand thus become the premier surgical quality-control instru-ment for heart surgeons. TEE has evolved to provide real-time2 and 3-dimensional imaging of heart and valve structuresas well as valvular hemodynamic performance with Dopplerspectral and color-flow imaging.

Despite no randomized data on patient-important outcomessupporting its routine use,2 intra-operative TEE (IOTEE) hasbecome widely utilized in cardiac surgery theaters worldwide.Studies totaling over 25,000 patients demonstrate a complicationrate ≤ 0.2% and mortality < 0.1% for TEE/IOTEE,2 a crucial safety

elena, MD, Mayo Clinic, 2edu (H.I. Michelena).

rved.

concept upon which a body of indirect evidence supporting theuse of IOTEE has been constructed. Certainly, improvement inpatient-important outcomes can be inferred from the results ofnonrandomized trials of test accuracy3 (i.e., IOTEE versus directsurgical observation for cardiac anatomy/valvular dysfunctionmechanisms, and IOTEE versus TTE for hemodynamic valvularassessment), provided that effective treatment for the abnor-malities detected by that test is available (i.e., additional pumpruns to correct residual abnormalities identified by IOTEE)and that test-related adverse effects are minimal.2 The aboveconditions are given for IOTEE.2 Furthermore, the use of IOTEEresults in non-planned surgical alterations at the pre-cardiopulmonary bypass (Pre-CPB) and post-cardiopulmonarybypass (post-CPB) junctures, where the post-CPB setting iscritical since it offers the opportunity of prompt recognition ofabnormalities which can be treated immediately, preventingfuture re-do surgeries, aswell as patientmorbidity andmortality.Thus, the timely presence of the echocardiographer during the

00 First Street SW, Rochester, MN, 55905.

Table 1 – Critical principles in perioperative VHDechocardiography.

Importance of Perioperative TTE

• Assess hemodynamic significance of valve lesions by TTE: theonly precondition for a perfect valve repair or replacement isthat the native valvular lesion is indeed severe

• Assess aortic stenosis peak velocity and mean gradientfrom multiple windows

• Assess right ventricular function• Assess TR severity (color scale ≥ 60 cm/s) and tricuspid

annular dimension• Assess MR and AR severity (color scale ≥ 60 cm/s) and repairability• Evaluate mitral annular calcification severity

(critical for mitral repair and replacement)• Evaluate LVOT obstruction

IOTEE Pre-CPB Goals

• Corroborate valvular dysfunction severity and refine mechanismsand approaches for effective communication to the surgeon

• Assess right and left ventricular systolic function• Assess severity of AR for cardioplegia planning• Search for unsuspected conditions i.e., thrombus, papilloma• Exclude ascending aorta atheroma that may affect cannulation• Rule out interatrial communication

IOTEE Post-CPB Goals

• Timely presence of echocardiographer in operating room• Assist surgeon in de-airing procedures• Reassess left and right ventricular systolic function• Anatomic and hemodynamic evaluation of valvular procedure

result under appropriate hemodynamic conditions of heart rate,blood pressure and intra-cardiac volume

Abbreviations and Acronyms

AR = aortic regurgitation

CPB = cardiopulmonary bypass

ERO = effective regurgitant orifice

HCM = hypertrophiccardiomyopathy

IMR = ischemic mitral regurgitation

IOTEE = intra-operative transthorac-ic echocardiogram

LV = left ventricle or left ventricular

LVOT = left ventricular outflow tract

MR = mitral regurgitation

PISA = proximal isovelocity surfacearea

SAM = systolic anteriormotion of themitral valve apparatus

TEE = transesophagealechocardiogram

TR = tricuspid regurgitation

TTE = transthoracic echocardiogram

VHD = valvular heart disease

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transition off of CBPfor goal-directed as-sessment of surgicalresults under appro-priate hemodynamicconditions, followedby effective commu-nication of detectedabnormalities andtheir mechanisms tothesurgeon, iscritical(Table 1). Commonpre-CPB surgical-altering IOTEE find-ings include patentforamen ovale, un-suspected mitralregurgitation (MR),aortic atheroma,endocarditis com-plications, intracar-diac thrombus andleft ventricular out-flow tract (LVOT)obstruction,2,4,5

whereas themajorityof post-CPB surgical-altering findings arerelated to less-than-satisfactory valvular

• Effective communicationof residual severity of valvular dysfunction,anatomy and mechanism of dysfunction

• Rule out ascending aorta hematoma or dissection

Importance of Post-Operative TTE

• Assessment of valvular function, left-right ventricular function,and presence of pericardial collections (i.e., hematomas) in theunstable patient during post-operative hospital stay

• Pre-discharge TTE serves as a baseline (“finger print”) for futurecomparison, especially for valvular function (native andprosthetic)

Table 2 – IOTEE impact according to surgical setting.

SurgicalSetting

Valvular HeartDisease a

Adult CardiacSurgery b

CABG c

Post-CPBIOTTE impact

4% 2.2–2.5% 0.8–1.0%

a Average of 8 major IOTEE valvular studies,2 driven by additionalpump runs for aortic and/or mitral repair surgeries.b Does not include adult congenital heart disease surgery,based on 2 large contemporary studies.6,7c Studies or sub-studies including primarily coronary artery bypasssurgery (CABG).6,8,9

intervention results, and less commonly to graft revisionsand other rare complications (i.e., ventricular septal defect,iatrogenic aortic dissection). Hence, the impact of post-CPBIOTEE is the greatest for valvular heart disease (VHD)2,6–9

(Table 2). Indeed, significant VHD affects 13% of patients≥ 75 years,10 primarily driven by MR and aortic stenosis(AS). This has led to a recent increase in surgical valvularprocedures, especially aortic and mitral; accompanied byimproved surgical survival trends. Echocardiography aidsthe surgeon in tailoring the surgical approach to the specificmechanism of valve dysfunction, identification of addi-tional abnormalities that may warrant intervention, andtimely intraoperative evaluation of surgical resultsallowing immediate correction of less than satisfactoryresults. Patients with moderate residual valve dysfunctionhave more postoperative complications and higher mortal-ity compared to those with a satisfactory valve surgeryresult,11 highlighting the importance of post-CPB identifi-cation and correction of more than mild valve dysfunctionbefore the patient leaves the surgical suite. For this processto be meaningful, the patient who reaches the operatingroom must have hemodynamically severe VHD establishedpre-surgically, thus the importance of perioperative TTE(Table 1).

Landmark practice guidelines for the application ofIO TEE have been developed12–15 and valvular repairand replacement are considered primary indications forIO TEE monitoring. Other primary indications for IOTEE include conditions commonly associated with

VHD: hypertrophic cardiomyopathy (septal myectomy),ascending aortic disease, and congenital heart disease.14

This review will not discuss the use of IOTEE incongenital heart disease.

Fig 1 – Left atrial appendage “de-aring”. Panel A depicts a post-bypass IOTEE of the left atrial appendage (LAA) with evidence ofechogenic “pocket” of air occupying the mid portion and LAA tip (arrows). Panel B captures the moment when the hand of thesurgeon “shakes” the left atrial appendage (arrows) and the air bubbles become evident. Panel C shows the full size/cavity ofthe LAA with few air bubbles remaining.

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IO TEE in stroke prevention

Perioperative stroke in cardiac surgery has an overall incidenceof persistent neurological deficits up to 4–5%.16 Manipulation of

Fig 2 – Recognizing etiology of aortic stenosis by echocardiographyAS. B. Short-axis systolic TTE view of the calcific AoV shows the tyinvolvement of the cusp edges and no commissural fusion. C. The pbelly of the cusps. D. Long-axis systolic pre-CPB IOTEE view ofcusp edges (arrows). E. Short-axis systolic pre-CPB IOTTE view ofusion and thickened cusp edges. F. The pathologic correlate of paneAbbreviations: AoV = aortic valve, LVOT = left ventricular outflow tN = non-coronary cusp.

the ascending aorta (potentially causing “sandblast” effect onatheroma) increases the likelihood of atheromatous debrisembolization. Protruding atheroma > 4–5 mm in thickness,mobile atheroma or complex atheroma (i.e., ulcerated orthrombosed) are indicators of increased embolic risk17 and

. A. Long-axis systolic TTE view of the LVOT and AV in calcificpical “stellate” opening of the valve without significant calcificathologic correlate of panel B showing calciumaccretion in thethe LVOT and AV in post-inflammatory AS with very thickf the post-inflammatory AoV shows the typical commissurall E showing commissural fusion and thickened cusp free edges.ract, Ao = aorta, R = right coronary cusp, L = left coronary cusp,

Fig 3 – Evaluating prosthetic valve mechanism by post-CPB IOTEE. Panel A shows a post-CPB IOTEE long-axis systolic framedepicting normal systolic excursion of the mechanical aortic prosthesis bileaflet mechanism. Panel B shows the same systolicframe in short-axis. Abbreviations: LA = left atrium, Ao = aorta.

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should be brought to the surgeon's attention before cannulation,especially if located in the ascendingaorta. Theuse of pre-CPB IOTEE,18 with minimal aorta handling and distal cannulationguided by TEE in selected patients may have the potential ofreducing strokes. Guidelines for epiaortic intra-operative ultra-soundutilizationhave emerged19 but the real benefit of epiaorticultrasound is controversial.2 We recommend a thorough pre-CPB IO TEE evaluation of the entire aorta in multiple planes andthe use of epicardial ultrasound in rare cases where TEE imagesare suboptimal, unclear or suggestive of complex ascendingaortic atheroma, and/or if requested by the surgeon.

The use of CPB is also an independent predictor of stroke16

and air embolism is a likely mechanism. Cardiotomy for valvedisease likely predisposes to air trapping, and specific highbuoyancy sites or pockets where air can hide are the leftventricular apex, left atrium and appendage (Fig 1), right sinusof Valsalva and pulmonary veins. These sites should beinspected by the echocardiographer20 and communicated tothe surgeon immediately. IO TEE-guided “deairing” proceduresare associated with decreased markers of subclinical cerebralinjury.21 The critical time to guide deairing is duringdecannulation/“coming off” CPB, thus the need for timelypresence of the echocardiographer at that juncture (Table 1).

Aortic valve

The AS lesion and its severity

Preoperative TTE determination of severity is critical in AS.Parallel cursor alignment with the LVOT/aortic flow forcontinuous-wave Doppler mean gradient analysis can beobtained in the transgastric long and deep transgastric axes,13

however, quality views are not readily obtainable in all patients,highlighting the importance of preoperative TTE evaluation(Table 1), where multiple windows can be explored. Calcificstenosis presents without significant commissural fusion or

free-edge involvementwithmost calciumaccretion on the bellyof the cusps (Fig 2), while post-inflammatory stenosis hascommissural fusion, free-edge involvement and cusp retraction(Fig 2). Because of its high image resolution, TEE allows directplanimetry of the open valve in systole in the basal short axisview. However, although studies22 have shown correlationbetween TEE planimetry and valve area calculations, othershave questioned its reliability.23 Furthermore, the accuracy ofplanimetry depends on tomographic plane, amount of calciumand gain-settings, hence, although helpful, planimetry shouldnot be used as sole indicator of AS severity. Two-dimensionalevaluation of the systolic aortic valve mobility (systolic excur-sion) in different planes is invaluable in severity estimation forthe experienced echocardiographer.

Special issues in AS

IO TEE has shown high accuracy in predicting annular sizecompared to surgical obturator,24 potentially reducing CPBtime by 10 to 30 minutes of thaw time when allografts orhomografts are used. Recently, attention has been focused onthe impact of patient–prosthesis mismatch in the aorticposition25; moderate and severemismatch being independentpredictors of long-term morbidity and mortality, thus, atten-tion to annular size and body surface area of the patientduring pre-CPB IO TEE is warranted. Specific mismatchprevention algorithms have been published.26 A calcifiedand small annulus (< 2 cm) should be brought to thesurgeon's attention; annular debridement and/or pericardialpatch aortic enlargementmaybe required to insert an adequatesized prosthesis. Identification of a hypertrophied septum orsubvalvular LVOT obstruction due to left ventricular hypertro-phywith systolic anteriormotion of themitral apparatus (SAM)is important since concomitant septal myectomy may berequired. Post-CPB evaluation includes transgastric assessmentof the prosthesis' mean gradient, systolic excursion of theprosthetic components (Fig 3) and careful exploration for

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perivalvular leaks (Fig 4) inmultiple views andwith physiologichemodynamic conditions (Table 3).

The aortic regurgitation (AR) lesion

Since aortic valve repair may be a safe alternative to valvereplacement in selected patients with pure AR, correctlyidentifying the mechanism of AR to guide the surgeon'sapproach is paramount. TEE provides accurate anatomicassessment of AR lesions and the functional anatomy of ARdefined by TEE is strongly predictive of valve repairability andpostoperative outcome.27 Pathologic mechanisms in AR canbe classified into: a. normal cusp mobility: mobility is normalbut there is cusp separation or perforation. It is important to

Fig 4 – Communicating periprosthetic leak location to the surgeonthe aortic position with a moderate jet of periprosthetic AR arisindirected posteriorly (P) towards the left atrium (LA). B. Short axisValsalva (R). The patient underwent a second pump run and defsystolic frame of a mechanical mitral valve prosthesis with a moappendage (LAA) and a trivial perivalvular leak jet (arrow-head)non-turbulent jets (red) represent normal intra-valvular “built-in”effectively repaired. Another way of reporting the findings is the mand the trivial jet located antero-laterally (A1-P1 area). Abbreviation

note that cusp separation (Fig 5) may occur due to dilatationof one or all 3 components of the functional aortic annulus28;the aorto-ventricular junction (conventional aortic annulus),the sinuses of Valsalva and the sinotubular junction. Jetsarising from cusp separation are central if the dilatation of thefunctional aortic annulus is symmetric, but may be eccentricif it is asymmetric; b. excessive cusp motion: cusp prolapse,which may be partial (amenable to surgical plication) or involvethe entire cusp (amenable to surgical re-suspension),28where thejet is eccentric, directed away from the prolapsing cusp (Fig 5); c.restricted cusp motion: cusp retraction due to inflammatoryprocesses or valve sclerosis (central or eccentric jet). In bicuspidaortic valves, there is usually a combined mechanism affectingthe conjoined cusp; prolapse and retraction,29 although prolapse

. A. Post-CPB IOTEE long axis view (140º) of a bioprosthesis ing anteriorly (A), adjacent to the right ventricle (RV) andimage (50°) locates the origin of the jet to the right sinus ofect was successfully repaired. C. Post-CPB IOTEE shows aderate perivalvular leak jet (arrow) opposite to the left atrialdirectly adjacent to the left atrial appendage. Smaller centraljets or washing jets. This required a second CPB run andwasoderate perivalvular jet located posteromedially (A3-P3 area)s: LV = left ventricle, Ao = aorta.

Table 3 – Valve replacement specific post-CPB assessment.

• Verify normal occluder motion (mechanical) and ampleleaflet excursion and coaptation (biologic)

• Exclude periprosthetic regurgitation, on multiple planes,color scale ≥ 60 cm/s, and physiologic hemodynamic conditions

• Effective communication of periprosthetic leak severity and location• Measure gradient across the prosthesis with parallel alignment

to color flow, in multiple views. Report mean diastolic gradient(mmHg), blood pressure at acquisition and heart rate at acquisition

• Color flow Doppler documentation of normal physiologicprosthesis regurgitation (mechanical prostheses)

• Exclude LVOT obstruction by mitral prostheses• Exclude left circumflex coronary artery injury/occlusion

(MV replacement and repair)• Rule out iatrogenic fistula

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of the non-conjoined cusp has also been observed.30 Assess-ment of cuspmobility and jet direction during pre-CPB IO TEEis highly accurate in defining the AR mechanism.31 In thesetting of type A aortic dissection, pre-CPB IO TEE evaluation

Fig 5 – AR mechanisms. A. pre-CPB IOTEE short axis of the aortic vrelated to functional annulus dilatationwith normal cuspmobility,IOTEE view of a BAV in long axis at 130°. Note the prolapse (increacusps) in diastole. This generates an eccentric jet (panel D), posteriprolapsing cusp). Between the flow convergence and the body of tvena contracta defined as the smallest width measurable betweensurrogate for the effective regurgitant orifice. Abbreviations: LA = leBAV = bicuspid aortic valve, AR = aortic regurgitation.

of the AR mechanism can assist the surgeon in identifyingpatients likely to benefit from aortic valve repair.32 Incompleteleaflet closure (central jet), aortic leaflet prolapse (eccentricjet) and dissection flap prolapse are the main mechanisms(Fig 6).

AR severity

In all surgical scenarios requiring CPB, the surgeon must bealerted to the presence of more thanmild AR on pre-CPB sinceit may interfere with antegrade cardioplegia administration(Table 1) and result in inadequate myocardial preservation.

Quantification of native AR should be obtained preopera-tively by TTE or TEE. Doppler technology allows quantificationof the effective regurgitant orifice area (ERO)33 and regurgitantvolume with the use of the proximal isovelocity surfacearea (PISA) method, which has been validated for TEE,34 andshould be used in unclear cases. A simple, reliable measure-ment is the vena contracta which has been validated for TEE35

alve in diastole shows a triangular central coaptation defectgenerating a central jet ofAR by color-flow (panel B). C. Zoomedsed cusp mobility) of the anterior cusp (conjoined right–leftorly directed towards the anterior mitral leaflet (away from thehe jet, note the “neck” of the jet (arrows) which represents thethe flow convergence and the jet. The vena contracta is aft atrium, Ao = aorta, LVOT = left ventricular outflow tract,

Fig 6 – AR mechanisms in the setting of ascending aorticdissection (modified fromMovsowitz et al.32). A. Short axisdiagram shows normal diastolic trileflet coaptation and its longaxis correlate on the right. B. Short axis diagram shows centralcoaptationdeficiencydue to functional-annulusdilatation (longaxis small arrows), generating a central jet of AR (large arrow),see Fig 5. C. Short axis diagram depicts cusp prolapse due toaortic dissection flap reaching the root (long axis gray arearepresents false dissection lumen) and “unsuspending” thecusp, which generates a jet directed away from the prolapsedcusp (arrow). D. Long axis cartoon shows dissection flap (grayarea)prolapsing through the aortic valve coaptation surface andcausing a complex jet of AR (arrows). Allmechanisms shown inthis figure are amenable to repair by an experienced surgeon ifthe aortic valve tissue is suitable.Abbreviation: AR = aortic regurgitation.

Table 4 – Communicating peri-prosthetic leak location tothe surgeon.

Aortic Position

• Overall location: anterior versus posterior versus lateral• Specific location: in relation to the native right, left

or non-coronary sinus• See figure 4

Mitral Position

• Overall location by proximity to landmarks; aortic valve, left atrialappendage, interventricular–interatrial septum andposterior left atrial wall

• Specific location: anterior, antero-lateral, lateral, postero-lateral,posterior, postero-medial, medial, antero-medial—Use of 3D-IOTEEhighly recommended

• See figure 12

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and is accurately identified by TEE (Fig 5). Pulsed-waveDoppler holo-diastolic reversal of flow in the aortic arch byTEE is suggestive of significant AR.

Special issues in AR

Post-CPB IO TEE verifies the functional result with pressureand volume “back” in the aorta. After aortic valve repair,

coaptation tips located below the annular plane or presenceof residual AR, or coaptation length < 4 mm are predictors ofrecurrent 3+ AR within 2 years.36 After aortic valve replace-ment, trivial to mild paravalvular leaks are not uncommon,especially with the use of stentless bioprosthesis37 and afterrepair or replacement in valve endocarditis. These leaks,however, tend to resolve in > 50% of cases after anticoagulationreversalwith protamine, thus the importance of imaging beforeand after protamine administration. A vena contracta of 0.3 cmor less is highly predictive of complete leak resolution afterreversal with protamine.37 Perivalvular leaks and/or residualvalvular AR that are more than mild should prompt consider-ation of a second CPB run. Two basic aspects of the anatomiclocation of aortic perivalvular leaks should be described to thesurgeon: anterior (adjacent to the right ventricle) or posterior(adjacent to the left atrium) location and its relation to thecoronary sinus of the native valve (Table 4 and Fig 4).

Tricuspid valve

The tricuspid regurgitation (TR) lesion and its severity

Functional TR related to annular dilatation (central jet) ismore common than primary or organic (flail leaflets, leafletperforation, eccentric jet) and is a predictor of poor outcomein patients with concomitant left sided valvular disease.38

Historically, TR was often overlooked at the time of left-sidedvalve surgery39 and isolated tricuspid valve surgery followingprevious sternotomy, although it carries acceptable earlymortality, was associated with a decreased late survival freeof events. It is critical to review preoperative TTE imagesfor the severity of TR because it can be underestimated onpre-CPB IO TEE40 due to anesthesia-related hemodynamicchanges (Table 1). Even moderate TR must be reported to thesurgeon because it may warrant exploration and possiblerepair, particularly in the presence of left sided rheumatic orischemic heart disease.

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Special issues in TR

Unfortunately, recurrence of significant TR is not uncommondespite surgical correction,39 however, recurrence may bepredictable intraoperatively. Tricuspid annulus dilatation,39,41

use of repair techniques not involving placement of anannulus ring,42,43 amount of leaflet tethering (pulling of theleaflets toward the right ventricular apex),44 severe TR at

Fig 7 – Surgical mechanisms of MR. Regurgitation with normal leperforation, commonly generating a central jet. In excessive leafl(i.e., a flail or prolapsing posterior leaflet generates an eccentric, ais directed toward the affected leaflet (IIIb). A restricted posterior lemuscle due to previousmyocardial infarction remodeling, is overrposteriorly directed jet, towards the affected leaflet).

baseline43–45 and more than mild to moderate (> 2+) residualTR after repair45 are predictors of recurrence. Annulardilatation may be a predictor of future severe TR even if onlymild regurgitation is present at baseline,41 thus, observingprominent tricuspid annular dilatation46 regardless of thedegree of regurgitation should be communicated to thesurgeon because it could warrant surgical exploration andpotential repair. In the 4-chamber view, the normal diastolic

aflet mobility (I) occurs with annular dilatation and leafletet mobility (II), the jet is directed away from the affected leafletnteriorly directed jet). In restricted leaflet mobility (III), the jetaflet, tethered into the left ventricle from a displaced papillaryidden by the anterior leaflet in systole, generating an eccentric,

Fig 8 – 3DTEE “surgeon's view”. A. 3D IOTEE full-volume end-systolic frame (surgeon's view) shows the aortic valve (AoV) anteriorly,and each scallop of the anterior (A1, A2, andA3) and posterior (P1, P2, and P3)mitral leaflets. Medially is the posteromedial commissure(PM) of themitral valve, and laterally, the anterolateral (AL) commissure. Note the severe prolapse of P1which elevates above the otherscallops creating an orifice (arrow) of regurgitation. Panel B is a zoomed view of A2, P1 and P2 with color-flow (panel C) at end-systole,where the anatomic defect-jet origin link can be identified (arrow) as the jet arising from P1.

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tricuspid annular measurement between the base of thelateral and septal leaflets is 2.8 ± 0.5 cm, and shouldnot exceed 3.5 cm or 2.1 cm/m2. Continuous-wave Dopplermean diastolic gradient across the valve should be assessedpost-CPB and reported together with the heart rate duringacquisition (Table 3).

Mitral valve

The MR lesion

The most common cause of isolated surgery for MR in NorthAmerica is degenerative or organic. The mechanism of dys-function is leaflet prolapse and/or ruptured chordae (causingflail segments). The underlying pathology is myxomatousdegeneration or fibroelastic deficiency. The probability of repairis greater than 95–99% at experienced centers for both posteriorand anterior leaflets, even for Barlow's disease47 (multiplemyxomatous prolapsing scallops), especially in the absence

of annular calcification or leaflet restriction, as assessed byechocardiography. Any degree of annular calcification (usuallybest assessed by TTE, Table 1) should be communicatedto the surgeon at the pre-CPB juncture. There is a significantimmediate and long-term survival benefit in repairing insteadof replacing the valve for degenerative MR,48 hence theimportance of accurate echocardiographic definition of theexact mechanism of dysfunction (Fig 7) in order to assessrepairability. Repairability and basic organic MR mechanismscan be readily assessed by pre-operative TTE.49 In certainpatients with endocarditis, repair is also possible, particularlyof the anterior leaflet.50

Functional, ischemic MR (IMR) carries critical prognosticvalue, with mortality being directly proportional to severityof IMR,51 which is a disease of the left ventricle52 where“normal”mitral leaflets and chords are subjected to abnormalforces due to ischemic remodeling of the left ventricle (LV)which cause coaptation point separation and ventriculardisplacement of the leaflets toward the LV apex (tethering)rendering them tented and insufficient (Fig 7). Annuloplasty

Fig 9 – IOTEE evaluation of themitral valve. Schematic representation of completemitral valve assessment from themidesophageallevel. The level of the ultrasound sector “slicing” themitral valve is represented by the dotted lines over the posterior valvular planeof the heart cartoons on the left (the direction of the ultrasound beam is posterior → anterior). Eight different tomographic viewsobtainablewith a combinationof 4 different angle ranges (A-0°, B-45°, C-60–80° andD-110–130°) and shaftmanipulations are shown.The 8 tomographic views derived from each slice are in the triangular sectors as would be seen in the echocardiogrammonitor.Note that in position A-0°, the entire mitral valve can be evaluated by withdrawing (or flexing) or advancing (or retroflexing) theprobe, as explained under A.

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for IMR has been common practice, however, recurrentsignificant IMR is common53,54because only one aspect(annular dilatation) of a complex process is addressed, thus,sometimes a “good” replacement may be better than a “bad”

repair. However, new surgical approaches for reversal of LVremodeling are being explored and both preoperative TTE andIO TEE are destined to play a pivotal role in surgical planningand immediate evaluation of results.

Fig 10 – Transgastric evaluation of mitral commissures.The patient depicted had residual severe MR on unclearmechanism in the post-CPB juncture. The transgastric 2Dviewwas helpful in identifying the posteromedial commissure (A3-P3, panelA) as the culprit. Color-flowDoppler identified aprominentflow-convergence site at that commissure (arrow, panels B and C)which slid over the entire coaptation surface of the valve (panels Band C). A second pump-runwas required to repair the valve.Abbreviations: LV = left ventricle, LA = left atrium.

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The mitral IOTEE evaluation

Two important principles rule the echocardiographic approachinMR55: 1. the goal of surgery is restoring normal valve functionso themechanism of dysfunctionmust be identified, and 2. themechanism of dysfunction can be simplified into 3 basicfunctional abnormalities based on leaflet mobility; normalleaflet mobility, and excessive or reduced leaflet mobility

(Fig 7). The mitral leaflets have been anatomically divided in 3scallops, anterolateral, middle and posteromedial: A1, A2 andA3 for the anterior and P1, P2 and P3 for the posterior leaflet(Fig 8). There may at times also be 2 additional commissuralscallops, anterolateral and posteromedial, at the commissurallevel. A complete 2-dimensional assessment of the valve can beobtained from themidesophageal position bymanipulating theshaft at 0° (Fig 9) and dialing different degrees with shaftmanipulation (Fig 9).56–58 For identification of a flail leaflet, thepresence of a ruptured chord and eccentric jet have a 100%accuracy.59,60 IO TEE can accurately diagnose the mechanismfor MR in 90% ormore of cases based on leaflet mobility and jetdirection61(Fig 7). Evaluation of themitral valve “en-face” in thetransgastric short axis may correctly identify commissuralmitral regurgitation due to prolapsed or flail commissureswhich can be repaired with excellent echocardiographic long-term results (Fig 10). The 3-D surgeon's view is particularlyuseful in organic MR, where 2-D findings can be corroborated,prolapsing scallops can be prioritized, clefts identified,and the anatomic defect-jet origin link can be identified(Table 5 and Fig 8).

MR severity

Quantification of regurgitation should be obtained preopera-tively, as > 90% of MR can be quantified by experiencedcenters by TTE (Table 1). Intraoperatively, the severity of MR isconfirmed and “unsuspected” MR must be identified. Observ-ing a flail leaflet (associated with severe MR in 85% of cases) oran eccentric jet “wrapping around” the left atrium (Coandaeffect) should suggest the presence of significant MR.62 Obser-vation of the color-flow jet area alone may be misleading forestimation of severity, as eccentric jetsmay underestimate andcentral jets overestimate the degree of MR. Quantificationmethods using ERO and regurgitant volume derived from PISAand continuity have been extensively validated33,63 for TTE andTEE and should be used if time permits and in unclear cases.The Vena contracta has also been validated for TEE.64,65

General anesthesia decreases blood pressure, color jet areaand vena contracta causing an apparent reduction in theseverity of MR in about 50% of patients by IO TEE.66 Thisincludes all MR etiologies except severe MR due to flail leaflets.In patients with IMR, the severity may be erroneouslydowngraded in up to 90% of patients at the time of pre-CPB IOTEE67 reflecting the dependence of this lesion on loadingconditions. Administration of intravenous phenylephrine68 torestore LV afterload and volume infusion to restore preload, areoften required for adequate assessment of functional MR.69

Pulmonary vein systolic flow reversal can corroborate thepresence of severe MR70,71(especially when ≥ 2 pulmonaryveins not directly receiving the MR jet are involved) witha specificity and positive predictive value reaching 100%,however, its sensitivity is limited. Importantly, discordantpulmonary vein flow patterns have been noted among patientswith MR,72 hence the need to sample all pulmonary veins. It iscritical to understand that pulmonary vein systolic blunting isnot interchangeable with reversal and can be seen with anydegree of MR. Accurate description of how to effectively imageall 4 pulmonary veins has been published.73,74

Table 5 – Mitral valve repair (organic MR) pre and post-CPBIOTEE assessment.

Pre-CPB Assessment

▪ Confirm organic mechanism of MR▪ Assess severity of TR, communicate to surgeon both severitiesassessed by pre-op TTE and IOTEE

▪ Refine MR mechanism, combined 2D and 3D assessment▪ Identify prolapsed segment and scallop (s) involved▪ Identify flail segment and scallop (s) involved▪ Identify commissural MR▪ Identify clefts, their location and involvement in MR▪ In Barlow's disease, prioritize scallops wheremajor jets are originated,identify anatomic defect-jet origin link

▪ Identify mitral annular calcification-evaluate preop TTE if needed▪ Evaluate leaflet length and septal thickness as predictors ofpost-repair SAM

Post-CPB Assessment

• Severity of residual MR under physiologic hemodynamic conditions,effective communication of residual defect mechanismand anatomic location

• More than mild residual MR should prompt a second pump run• If MR is moderate or severe, exclude SAM as underlying mechanism• Measure gradient across MV aligned to flow, in multiple views• Exclude left circumflex coronary artery injury/occlusion

(i.e., new lateral-posterior wall regional wall motion abnormality)

Fig 11 – Mechanical mitral prosthetic regurgitation. A. Two-dimeventricle after a bileaflet mechanical mitral valve replacement (Mphysiologic MR (arrows). Compare to panel B in another patient sincomplete prosthetic closure in systole caused by entanglemenAbbreviation: LA = left atrium.

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Special issues in MR

Post-CPB evaluation after mitral valve replacement includesevaluation of prosthetic components and search forperivalvular leaks at physiologic loading and heart rateconditions (Table 3). The most common complication aftermitral valve replacement is periprosthetic leakage (especiallywith severely calcified mitral annuli), nonetheless, vigilancefor mechanical dysfunction of the valve itself causingprosthetic leaks75 is critical, so familiarity with the “built-in”leakage volume of the prosthesis76,77 is important and must bedifferentiated from abnormal prosthetic MR (Fig 11). ProstheticMR or obstruction can result from a prosthetic disc beingentangled to residual native sub-valvular support apparatus.78,79

Despite excellent correlation between periprosthetic leaksdescribed by TEE and direct surgical observation,80 communicat-ing its location to the surgeoncanbe confusing. Localizing theMRin reference to anatomic landmarks is critical (Table 4 and Fig 12).Perivalvular leaks are found more commonly after replacementin the mitral than the aortic position and are usually mild,81

decreasing by up to 50% after protamine anticoagulation reversalhas been administered.82 More-than-mild perivalvular regurgita-tion usually requires a second CPB run for closure.

In mitral valve repair, the presence of “less than echo-perfect”83 results from repair (1+ or 2+ residual MR) does not

nsional post-CPB midesophageal long-axis view of the leftVR) during systole with Doppler color-flow showing “built-in”howing 2 large jets (arrow) of intraprosthetic severe MR due tot of the prosthesis with residual native valve tissue.

Fig 12 – Anatomy and effective communication of mitralperiprosthetic leaks. A. shows a wide full-volume 3D TEE viewof a mechanical mitral prosthesis with surrounding structures.B. Note the aortic valve (AV) anteriorly, the left atrial appendage(LAA) anterolaterally and the inter-atrial septum (IAS)medially.This patient has had several percutaneous vascular plugs(mp, panel A) placed medially and one plug posterolaterally(p, panel A), that is between the LAA and the posterior aspect ofthe sewing ring. In this manner, leaks close to the AV areanterior, opposite to theAVare posterior, leaks close to the LAAare anterolateral and those opposite to the LAA areposteromedial. Note in Fig 4, that the trivial peri-leak isanterolateral (by the LAA) and the moderate leak isposteromedial (opposite to the LAA).

Fig 13 – Pre-CPB IOTEE evaluation of post-mitral repair risk oSAM. The ratio of the coapted systolic lengths of the anteriorand posterior leaflets (AL/PL ≤ 1.3) and the coaptation pointto septal distance (CS) (≤ 2.5 cm) have emerged as predictorsof post-mitral repair SAM. A long, redundant anterior leafletand an acute (usual angle between aortic and mitral annularplanes is approximately 135°) angle (α), are associated withpost-repair SAM.

Table 6 – Septal myectomy pre and post-CPB IOTEEassessment.

Pre-CPB Assessment

• Identify site of LVOT obstruction. Note that obstruction may beinduced in the OR by PVC induction or Isuprel infusion. Note thatobstruction may be mid-cavitary without LVOT component

• Extent of SAM-septal contact lesion• Maximum septal thickness at site of LVOT obstruction and its

distance from the aorto-ventricular junction• Distance of septal contact lesion from aorto-ventricular junction• Presence of anomalies of the submitral valvular apparatus,

i.e., papillary muscle hypertrophy, aberrant muscle bundles, etc• Mitral valve anatomic abnormalities and severity/mechanism of MR

Post-CPB Assessment

• Septal thickness at site of myectomy• Residual LVOT and/or intra-cavitary peak gradient• Severity and mechanism of residual MR• Presence and severity of AR• Rule out ventricular septal defect in multiple views• Identify septal perforator “bleeders”

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increasemortality overtimebut increases the risk of reoperation.In our practice, persistent grade more-than-mild residual MRmandates a second CPB run for correction and the surgeonneeds to understand the mechanism of malcoaptation andlocation of the residual MR in a timely fashion (Table 5).Markedly restricted/stenotic mitral repairs may result fromrigid leaflets, constricting annular calcification, undersizedannuloplasty rings or large edge to edge sutures such as Alfieristitch. Other complications observed after repair include LVOTobstruction due to SAM, residual clefts, prolapse, annular

f

dilatation, and suture dehiscence.84 Of these, LVOT obstructiondue to SAMhas been themost studied andhas been described in1 to 9% of mitral valve repairs.85–87 SAM occurs when redundantvalve tissue is displaced anteriorly and “sucked” into the LVOT

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during systole causing various degrees of outflow obstructionand posteriorly-directed MR. Evaluation of SAM includes LVOTgradient measurement. If a significant gradient is encountered(i.e., > 30 mmHg), medical management is attempted by in-creasing the left ventricular preload with intravenous volume,discontinuing/decreasing inotropes and/or adding beta-blockersto decrease LV hypercontractility. If the gradient continues to besignificant, a second CPB run may be considered, although bothSAM and LVOT gradients tend to improve spontaneously overtime87,88 and most patients can be managed medically. IO TEEmay be predictive of the likelihood of SAM at the pre-CPBstage89,90 (Fig 13). Pre-CPB identification of patients at highrisk for SAM may prompt surgical techniques directed at itsprevention.86,91,92 Our approach is to subjectively assess thelength and redundancy of the leaflets (especially the anterior),the angle between the mitral and aortic annular planes, thepresence of a subaortic septal bulge or pre-CPB SAM and advicethe surgeon accordingly (Fig 13). A long, redundant anteriorleaflet and an acute (usual angle between aortic and mitralannular planes is approximately 135°) angle, have also beenassociated with post-repair SAM.

Minimally-invasive mitral valve repair is becoming morecommon as it reduces hospital-length-of-stay and recuperation-time by virtue of sternotomy avoidance. In these cases, the onlydifference in the IOTEE evaluation of the procedure residesin the venous cannulae positioning in the superior and inferiorvena cavae, as well as verification of the arterial cannulationwire in the descending thoracic aorta and safe transitionon to cardiopulmonary bypass confirming the absence ofaortic dissection.93

Hypertrophic cardiomyopathy

In obstructive hypertrophic cardiomyopathy (HCM), septalmyectomy is the primarymechanical intervention. Pre-CPB IOTEE may identify significant mitral abnormalities such asprolapse, flail leaflet, or abnormal mitral support promptingadditional mitral surgery in up to 7% of patients.94 FunctionalMR in HCM is usually posteriorly-directed and related to SAM.However, the mitral valve may be structurally abnormal inHCM, particularly if 3D IOTEE is used for evaluation,95 andcomplex, multidirectional jets of MR may be observed by pre-CPB IOTEE. Unless clear evidence of severe prolapse or flailsegment is observed pre-CPB, no intervention should berecommended for the mitral valve until it is re-evaluated bypost-CPB IOTEE under physiologic hemodynamic conditionsand SAM absent. Post-CPB IO TEE shows new findings in up to7% of patients (including incomplete myectomy and severeresidual MR) of which half may require a second pump run. Itis important to determine if the residual MR is related only tosystolic anterior motion (eccentric posteriorly directed jet)or if there is a primary coaptation defect of the leafletscausingMR independently of systolic anterior motion (usuallya central jet or a combination of posteriorly directed andcentral jets). Complications following myectomy, namelyventricular septal defect and significant AR, must also beexcluded before the patient leaves the OR (Table 6).

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