Minimally invasive mitral valve surgery: a systematic review

12 Pages·2008·0.37 MB·English

Minimally invasive mitral valve surgery: a systematic review and meta-analysis
Paul Modi, Ansar Hassan and Walter Randolph Chitwood, Jr.
Eur J Cardiothorac Surg 2008;34:943-952
DOI: 10.1016/j.ejcts.2008.07.057
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The European Journal of Cardio-thoracic Surgery is the official Journal of the European Association
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EuropeanJournalofCardio-thoracicSurgery34(2008)943—952
www.elsevier.com/locate/ejcts
Review
Minimally invasive mitral valve surgery: a systematic review
and meta-analysis
Paul Modi, Ansar Hassan, Walter Randolph Chitwood Jr.*
EastCarolinaHeartInstitute,Greenville,NC,USA
Received23May2008;receivedinrevisedform19July2008;accepted28July2008;Availableonline30September2008
Summary
Themitralvalvehasbeentraditionallyapproachedthroughamediansternotomy.However,significantadvancesinsurgicaloptics,instrumenta-
tion,tissuetelemanipulation,andperfusiontechnologyhaveallowedformitralvalvesurgerytobeperformedusingprogressivelysmallerincisions
includingtheminithoracotomyandhemisternotomy.Duetoreportsofexcellentresults,minimallyinvasivemitralvalvesurgeryhasbecomea
standardofcareatcertainspecializedcentersworldwide.Thismeta-analysisquantifiestheeffectsofminimallyinvasivemitralvalvesurgeryon
morbidityandmortalitycomparedwithconventionalmitralsurgeryanddemonstratesequivalentperioperativemortality(1641patients,oddsratio
(OR)0.46,95%confidenceinterval0.15—1.42,p=0.18),reducedneedforreoperationforbleeding(1553patients,OR0.56,95%CI0.35—0.90,
p=0.02)andatrendtowardsshorterhospitalstays(350patients,weightedmeandifference(WMD)(cid:2)0.73,95%CI(cid:2)1.52to0.05,p=0.07).These
benefitswereevidentdespitelongercardiopulmonarybypass(WMD25.81,95%CI13.13—38.50,p<0.0001)andcross-clamptimes(WMD20.91,95%
CI8.79—33.04,p=0.0007)intheminimallyinvasivegroup.Case-controlstudiesshowconsistentlylesspainandfasterrecoverycomparedtothose
having a conventional approach. Data for minimally invasive mitral valve surgery after previouscardiac surgery are limited but consistently
demonstratereducedbloodloss,fewertransfusionsandfasterrecoverycomparedtoreoperativesternotomy.Long-termfollow-updatafrom
multiplecohortstudiesarealsoexaminedrevealingequivalentsurvivalandfreedomfromreoperation.Thus,currentclinicaldatasuggestthat
minimallyinvasivemitralvalvesurgeryisasafeandadurablealternativetoaconventionalapproachandisassociatedwithlessmorbidity.
#2008EuropeanAssociationforCardio-ThoracicSurgery.PublishedbyElsevierB.V.Allrightsreserved.
Keywords: Surgicalprocedures;Minimallyinvasive;Thoracicsurgery;Video-assisted;Mitralvalveinsufficiency
1.Introduction adopted MIMVS and have published favorable results as
single-center observational and comparative studies. A
Minimallyinvasivemitralvalvesurgery(MIMVS)doesnot recentmeta-analysisofminimalaccessaorticvalvereplace-
refer to a single approach but rather to a collection of ment suggested only marginal benefits for intensive care
newtechniquesandoperation-specifictechnologies.These unitstay(ICU)andhospitalstayoverconventionalsurgery,
includeenhancedvisualizationandinstrumentationsystems despite longer operative times [2]. As yet, no such meta-
aswellasmodifiedperfusionmethods,alldirectedtoward analysis is available for MIMVS despite nearly 10 years of
minimizingsurgicaltraumabyreducingtheincisionsize[1]. investigationaldata.
Inthemajorityofcases,MIMVShasbeenperformedthrough Changes in surgical indications, largely due to a better
either a right anterior minithoracotomy or a hemisternot- understandingofthenaturalhistoryoforganicmitralregur-
omy. The belief that this results in less surgical trauma, gitation and the increased use of repair techniques, have
blood loss, transfusion and pain, which translates into a increased the number of minimally symptomatic patients
reduced hospital stay, faster return to normal activities, withdegenerativediseasebeingreferredforelectiverepair
lessuseofrehabilitationresources,andoverallhealthcare [3,4]. For MIMVS to become accepted widely, at least
savings,hasdriventhisdevelopment.Scepticismsurround- equivalent, if not better, short- and long-term outcomes
ing MIMVS has focused on the potential ‘trade-off’ of must be demonstrated compared with sternotomy opera-
incisionsizeagainstthesafetyandexposureofestablished tions. This evidence should ideally come from large, multi-
techniqueswithprovendurable long-termresults.Despite center prospective randomized controlled trials (RCT) that
criticism over the last decade, various institutions have compare minimally invasive with conventional sternotomy-
basedmitralsurgery.However,thereareonlytwosmallRCTs,
oneofwhichreportsdatacombinedwithminimallyinvasive
* Correspondingauthor.Address:EastCarolinaHeartInstitute,EastCarolina
aortic valve replacement [5,6]. The ability to conduct an
University,PittCountyMemorialHospital,600MoyeBoulevard,Greenville,NC
effective RCT now would be compromised severely as pati-
27834,USA.Tel.:[phone];fax:[phone].
E-mailaddress:[email protected](W.R.ChitwoodJr.). ents and healthcare providers have preconceived notions
1010-7940/$—seefrontmatter#2008EuropeanAssociationforCardio-ThoracicSurgery.PublishedbyElsevierB.V.Allrightsreserved.
doi:10.1016/j.ejcts.2008.07.057
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944 P.Modietal./EuropeanJournalofCardio-thoracicSurgery34(2008)943—952
about surgical approaches. This attitude would render Endoscopy’ANDwith‘Mitralvalveinsufficiency’,‘Mitralvalve
patients unlikely to participate in a trial where randomiza- prolapse’, and ‘Mitral valve’. To reflect contemporary prac-
tion tosternotomy as acontrolcohort wouldbe possible. tice,thesearchwaslimitedtothelast10yearsandadditional
Intheabsenceoflargewell-designedRCTs,dataregarding limits were English language citations and human subjects.
short- and long-term outcomes are available from multiple The bibliographies of retrieved articles were searched for
case-control studies and observational studies. The aim of relevantarticles.Inaddition,the‘relatedarticles’functionin
this report is to review the published randomized and PubMedwasusedasafurthercheckofrigor.Wheremultiple
nonrandomizedcomparativestudiesthatcompareminimally cohort studies were published by a single institution, the
invasive endoscopic mitral valve surgery, excluding tele- largestormostinformativestudywasincluded.
manipulation, to conventional approaches. Moreover, we
integratemeta-analyticaldatatodrawmoreusefulconclu- 3.2.Inclusioncriteria formeta-analysis
sionsaboutimportantshort-andmid-termoutcomemetrics.
Long-term outcomes are assessed using multiple large Intra-operativestudyvariablesincludedCPBandXCtimes,
cohorts, tocompare theseto publishedsternotomy data. and postoperative ones were mortality, neurologic events
(CVA), reoperation for bleeding, new atrial fibrillation (AF),
intensive care unit (ICU) times, and hospital length of stay
2.Overview oftheevolution ofminimally invasive (LOS). The guidelines of the Meta-Analysis of Observational
mitralvalve surgery StudiesinEpidemiologygroupwerefollowed[16].BothRCTs
and case-control studies were used for the meta-analysis if
Inthemid-1990s,surgeonsbegantoexplorethepotential theyincludedatleastoneoftheoutcomesofinterest.Reports
advantagesofminimizingincisionsizeduringcardiacsurgery. presentingdataforminimallyinvasiveaorticandmitralvalve
CosgroveandCohn independently showed that mitral valve surgery were only included if the mitral valve data were
operations could be performed safely and efficiently using presentedseparately;studiesreportingreoperativedatawere
either parasternal or hemisternotomy incisions. Complica- excludedfromthemeta-analysis.Studiesinwhichdatawere
tionsincludingslowerhealing,increasedlungherniation,and notpresentedasmeanandstandarddeviation(SD)orifthis
less cosmetically appealing results led to the former being wasnotcalculablewereexcludedfromtheanalysis.
abandoned [7,8]. Carpentier performed the first video-
assisted mitral valve repair through a minithoracotomy in 3.3.Statistical analysis
Februaryof1996[9].Soonafter,theEastCarolinaUniversity
groupperformedthefirstmitralvalvereplacementthrougha Meta-analyses were performed either using odds ratios
minithoracotomy, using video-direction, a transthoracic (OR) or weighted mean differences (WMD) as the summary
aortic clamp, and retrograde cardioplegia [10,11]. In 1997, statisticforbinaryorcontinuousvariables,respectively.The
we presented our first experience with 31 video-assisted analyseswereperformedaccordingtotherecommendations
mitraloperations,reportinga30-daymortalityrateof3.2% oftheCochraneCollaborationandtheQualityofReportingof
andnomajorcomplications[12].In1998,Mohrreportedthe Meta-analyses guidelines [17]. An OR less than one or WMD
LeipzigUniversityexperienceusingport-access(PA)technol- lessthanonefavorsMIMVSoversternotomy.Randomeffects
ogy, which was based on endo-aortic balloon occlusion modelswereusedastheseassumevariationbetweenstudies
(EABO) rather than direct aorticclamping [13]. andarepreferredforsurgicaldataasselectioncriteriaand
The next major development was the introduction of a risk profiles for patients differ between centers. Statistical
voice-controlledroboticcameraarm(AESOP3000,Computer significance was set at p<0.05. Data were analysed using
MotionInc.,SantaBarbara.CA,USA)whichallowedprecise ReviewManagerversion4.2.10(TheCochraneCollaboration,
tremor-freecameramovementswithlesslenscleaning.This Oxford, England).
technologytranslatedintoreducedcardiopulmonarybypass
(CPB)andcross-clamp(XC)times[14,15],andenabledeven
smaller incisions with better valve and subvalvar visualiza- 4.Results
tion.Thenextevolutionaryleapinendoscopicmitralsurgery
was the development of three-dimensional (3D) vision and Weidentified43publishedreportsandofthesetherewere
computer-assisted telemanipulation that could transpose twoRCTs,17case-controlstudies,and24cohortstudies.Of
surgical movements from outside the chest wall to deep these studies, one RCT and ten case-control studies,
within cardiac chambers. Currently, the most widely used publishedbetween1998and2005,mettheinclusioncriteria
system is the Da VinciW telemanipulation system (Intuitive (Table1).Cohortpatientsnumbered2827,with1358inthe
Surgical Inc., Mountain View,CA). MIMVSgroupand1469intheconventionalsternotomygroup.
One comparative series was excluded [12] as more recent
inclusive data from the same group were found [14]. One
3.Patients andmethods reportcontaineddatafromtheSocietyofThoracicSurgeons
(STS) database as the control arm and therefore was
3.1.Literaturesearch excluded[18].Onereportpresentedresultsformitralvalve
repair (MVP) and replacement (MVR) separately without
The MEDLINE search strategy combined ‘Cardiac surgical presenting a combined group; the data for each were
procedure’ with the following MeSH terms: ‘Surgical proce- therefore analysed as independent studies [19]. The only
dures,minimallyinvasive’,‘Thoracicsurgery,video-assisted’, randomizedstudyincludedinthemeta-analysiswasbyDogan
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P.Modietal./EuropeanJournalofCardio-thoracicSurgery34(2008)943—952 945
Table1
Studiescomparingminimallyinvasivemitralvalvesurgerytosternotomy
Study,year,reference Period No.of Valve Approach Design Importantfindings
patients
MI St
Gloweretal.(1998)[21] N/A 21 20 MV MT CC MIgrouphadlongerCPBtimes,bettervalvar/subvalvar
visualization,returnedtonormalactivity5weeks
aheadofsternotomypatients
Asheretal.(1999)[29] 1/96—9/96 100 100 MV,AV Notdefined CC MIgrouphadlongerCPB/XCtimes,shorterhospitalstay
Schneideretal.(2000)[27] N/A 21 13 MV MT CC MIgrouphadlongerCPBtime,nodifferenceincerebral
microembolicrate
Grossietal.(2001)[20] 5/96—2/99 100 100 MV MT CC Reported1yearresults:nodifferenceinresidualMR,
freedomfromreoperationorfunctionalimprovement
betweengroups
Felgeretal.(2001)[14] 9/96—11/00 127 100 MV MT CC RoboticdirectionwithAESOPledto#bloodloss,
ventilationandhospitalstaycomparedtoStgroup,
andalso#CPBandXCtimescomparedtomanually
directedvideoscope
DeVaumasetal.(2003)[26] N/A 10 10 MV PS,8-10cm CC PSgrouphadlongerCPB/XCtimes,"bloodloss
McCreathetal.(2003)[30] 3/90—10/00 214 87 MV MT CC ReducedacuterenalinjurywithMIapproach
Gaudianietal.(2004)[22] 1/97—12/02 205 616 MV UHS, CC ShorterhospitalstayforMIrepair;lessCVAforMI
LHS,MT replacement.
Mihaljevicetal.(2004)[24] 7/96—4/03 474 337 MV LHS,PS CC MIgroupwerelowerriskpatients.Lowperiopmortality
inbothgroups(0.2%vs0.3%).5-yearsurvivalbetter
forMIgroup(95%vs86%,p=0.03)
Doganetal.(2005)[5] N/A 20 20 MV MT R IntraoperativeproblemwithEABOin45%.Nodifference
inmarkersofmyocardialandcerebralinjury,or
pulmonaryandneuropsychologicaltestsbetweengroups
Ryanetal.(2005)[19] 12/97—12/04 117 117 MV MT CC MIgrouphadlongerCPB/XCtimesforrepair,otherwise
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
nodifferences
Cohnetal.(1997)[8] 7/96—4/97 50 50 MV,AV PS,UHS CC MIgrouphadlongerCPBandXCtimes,#transfusion,
greaterpatientsatisfaction,lesspain,fasterreturn
tonormalactivity,charges20%less
Chitwoodetal.(1997)[12] 5/96—3/97 31 100 MV MT CC MIgrouphadlongerCPB/XCtimes,lesstransfusion,
fewerre-explorations,reducedCVA,shorter
ICU/hospitalstays,reducedcharges(#27%)
andcosts(#34%)
Reichenspurneretal. 1/97—98 100 100 MV MT CC OnlydifferencewasreducedAFinMIgroup
(1998)[18]
Grossietal.(1999)[23] 1/94—12/98 111 259 MV,AV MT CC Assessedpatients(cid:3)70yearsold.MIgrouphadlower
sepsis/woundcomplications,lessFFP,shorter
hospitalstay
Waltheretal.(1999)[32] 10/96—5/97 129 209 MV,AV, MT,UHS CC MTgroupapproachhadlowerpainlevelsfromday3
CABG onwardsduetobetterthoracicstability
Hamanoetal.(2001)[6] 4/97—12/98 21 27 MV,AV PS67%, R NodifferenceinCPB/XCtimes,transfusion
UHS29%, requirementsorSIRSbetweengroups
LHS4%
Grossietal.(2001)[25] 5/96—10/98 109 88 MV,AV MT CC MIgrouphadsimilarmortality,longerCPBtimes,
shorterhospitalstay,fewertransfusionsandseptic
complications
Yamadaetal.(2003)[28] 1/99—6/01 66 50 MVAV LHS CC MIgrouphadlongerCPB/XCtimes,lessanalgesics,
lessdelirium,earlierfoodintakeandFoleyremoval,
andshorterICUstay
Studiesabovethedottedlinemettheinclusioncriteriaformeta-analysis.AV,aorticvalve;CC,case-control;CPB,cardiopulmonarybypass;CVA,cerebrovascular
accident;EABO,endoaorticballoonocclusion;FFP,freshfrozenplasma;LHS,lowerhemisternotomy;MI,minimallyinvasive;MT,minithoracotomy;MV,mitralvalve;
N/A,notavailableintext;PS,rightparasternal;R,randomized;St,sternotomy;UHS,upperhemisternotomy;XC,cross-clamp.
etal.inwhich20patientsineacharmwerereportedtohave and conventional approaches [12,14,18—26]. In the largest
equivalentfindingsofabilitytorepairthevalve,CPBandXC study by Mihaljevic et al. 474 minimally invasive mitral
times,markersofmyocardialandcerebraldamageaswellas operations (mostly lower sternotomy and right parasternal)
pulmonary and neuropsychological tests [5]. Although the werecomparedwith337mediansternotomyprocedures.The
meanvaluesforventilationtime,ICUtime,hospitalstay,and perioperative mortality was 0.2% for the minimally invasive
red blood cell transfusion were all lower in the MI group, groupandthiscomparedfavorablywith0.3%inthesternotomy
these valuesdid not reach statistical significance. cohort.However,theMIMVSpatientswerefoundtobealower
risk group (better ejection fraction, more repairs, less
4.1.Mortality symptomatic) and noattempt was made toadjust for these
differences[24].Grossietal.matched88patientsundergoing
Ofthe11comparativestudiesevaluatingmortality,none minimallyinvasiveaorticandmitralvalvesurgeryovera2.5-
foundasignificantdifferencebetweentheminimallyinvasive yearperiod(througheithera2ndor4thinterspaceincision)to
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946 P.Modietal./EuropeanJournalofCardio-thoracicSurgery34(2008)943—952
Fig.1. Overallmeta-analysisofperioperativemortality,reoperationforbleedingandhospitallengthofstay.Thediamondrepresentsthesummaryoddsratio(OR)
fromthepooledstudieswith95%confidenceintervals(CIs)andissignificant(p(cid:4)0.05)ifitdoesnottouchthecentralverticalline.Squaresforeachstudyshowpoint
estimatesoftreatmenteffect(OR)withthesizeofthesquarerepresentingtheweightattributedtoeachstudy;horizontalbarsshow95%CIsforthesestudies.df,
degreesoffreedom;MIS,minimallyinvasivesurgery;MVP,mitralvalverepair;MVR,mitralvalvereplacement.
patientshavingthesamevalvesurgeryviaasternotomy[25]. his early series, Mohr reported an 18% incidence of post-
Theydemonstratednosignificantdifferenceinhospitalmor- operativeconfusion;however,continuousCO insufflationwas
2
tality (3.7% vs 3.4%, respectively) between groups, even notusedasinmorerecentseries[13].Tenstudiesreportedno
thoughmeanCPBtimeswere30minlongerintheMIgroup.Six differenceintheincidenceofstroke[14,18—21,23—27],while
studies met the inclusion criteria for our meta-analysis and two showed a reduced incidence with a minimally invasive
revealednosignificant mortality difference between groups approach [12,22]. There was no significant difference in
(1641patients,OR0.46,95%CI0.15—1.42,p=0.18)(Fig.1, neurological events on meta-analysis of six eligible studies
Table2). (1801patients,OR0.66,95%CI0.23—1.93,p=0.45).Schneider
et al. used trans-cranial Doppler to detect cerebral micro-
4.2.Neurologicalevents emboli in 21 MIMVS patients undergoing endoaortic balloon
occlusion with continuous CO chest cavity insufflation.
2
Due to restricted access with minimally invasive cardiac Thesewerecomparedto14patientsundergoingconventional
operations, there continues to be concern that inadequate mitral surgery [27]. They found no significant difference in
deairingcancauseahigherincidenceofneurologicalevents.In thecerebralmicroembolicratebetweeneithertechnique.
Table2
Meta-analysisofoutcomes
Outcome No.ofpatients No.ofstudies OR/WMD(95%CI) pvalue Heterogeneity,x2 x2,pvalue
Mortality 1641 6 0.46(0.15to1.42) 0.18 1.82 0.77
Stroke 1801 6 0.66(0.23to1.93) 0.45 6.77 0.24
CPB 871 8 25.81(13.13to38.50) <0.0001 27.05 0.0003
XC 671 7 20.91(8.79to33.04) 0.0007 24.98 0.0003
Re-opforbleeding 1553 5 0.56(0.35to0.90) 0.02 0.63 0.96
NewonsetAF 539 4 0.86(0.59to1.27) 0.45 2.25 0.52
ICUstay 309 4 (cid:2)0.36((cid:2)0.80to0.08) 0.1 3.26 0.35
Hospitalstay 350 5 (cid:2)0.73((cid:2)1.52to0.05) 0.07 1.75 0.78
AF,atrialfibrillation;CPB,cardiopulmonarybypasstime;ICU,intensivecareunit;XC,cross-clamptime.
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P.Modietal./EuropeanJournalofCardio-thoracicSurgery34(2008)943—952 947
4.3.Operative times criteria for the meta-analysis that showed a significant
reduction in reoperation for bleeding with a MI approach
TherewereconsistentfindingsthatCPBandXCtimeswere (1553 patients, OR0.56, 95% CI0.35—0.90, p=0.02).
longer with a minimally invasive approach. There was
evidence suggesting that parity can be achieved with 4.5.Atrial fibrillation (AF)
experiencewhilecertainhighvolumecentersreportshorter
operativetimeswithMIMVS[24].Ofthe16studiesreporting It has been suggested that a less traumatic surgical
cardiopulmonarybypasstimes,10describedlongerdurations approachwouldbealesspotenttriggerofpostoperativeAF.
forMIMVS.Seven of14 groupsreported longeraorticcross- Fiveofsixstudies,however,demonstratedthisnottobethe
clamp times [6,8,12,14,18—30]. Meta-analysis of eligible case [12,14,18,19,21,29], and on meta-analysis of four
studies showed significantly longer CPB (871 patients, WMD eligiblestudies,therewasnosignificantdifferencebetween
25.81, 95% CI 13.13—38.50, p<0.0001) and XC times (671 minimallyinvasiveandsternotomyapproaches(539patients,
patients, WMD 20.91, 95% CI 8.79—33.04, p=0.0007) with OR0.86,95%CI0.59—1.27,p=0.45).Asheretal.addressed
the minimallyinvasive approach. this question specifically in a cohort of 100 patients having
elective primary minimally invasive aortic or mitral valve
4.4.Bleeding, transfusion andre-exploration surgery and compared them to a matched control group
undergoing amediansternotomy[29].Theyfoundasimilar
Areductioninpostoperativehemorrhageandtransfusion prevalence of postoperative AF using either method, even
requirementshasbeensuggestedasapotentialadvantageof when stratified for valve type. However, the PAIR registry
minimally invasive valve surgery. This benefit is important reporteda10%incidenceofnewonsetatrialfibrillationwith
giventhesignificantmorbidityandmortalityassociatedwith theportaccesstechniquewhichislowerthanthatexpected
transfusions and re-exploration for bleeding [31]. Four for sternotomy [33].
comparative studies reported blood loss volume with three
utilizing a minithoracotomy [12,14,21] and one selecting a 4.6.Septic complications
parasternal approach [26]. Few of these series met the
inclusion criteria for the meta-analysis. Chitwood et al. Theincidenceofsepticwoundcomplicationsislesswith
demonstrated no difference in blood loss or blood product thoracotomythanmediansternotomy.Ofthethreestudiesof
transfusions in 31 videoscopic mitral procedures compared mini-thoracotomymitralvalvesurgerythatreportedwound
with a conventional sternotomy, despite fewer re-explora- complicationscomparedtomediansternotomy,Grossietal.
tions for bleeding [12]. The addition of a voice-activated reportedanincidenceof0.9%and5.7%formini-thoracotomy
robotic camera arm (AESOP 3000, Computer Motion, Inc., and sternotomy cases, respectively (p=0.05) [25]. This
Galeta,CA)ledtoareductioninbloodlossaswellasCPBand increasedto1.8%and7.7%,respectively,inelderlypatients
XC times. Nevertheless, there was no significant difference (p=0.03)[23],whereasFelgeretal.reportednosignificant
either in the percentage of patients receiving transfusions difference [14].
or the amount of blood products transfused [14]. In a
consecutive series of 41 patients undergoing either port 4.7.Painandspeed ofrecovery
access(n=21)orsternotomy(n=20)mitralsurgery,Glower
et al. demonstrated no significant difference in chest tube OfallthepotentialbenefitsofMIMVS,areductioninpain
drainage or transfusion requirements despite longer CPB and faster return to normal activity is the most consistent
times in the former [21]. finding. All four studies that measured postoperative pain
Three of 10 studies showed reduced transfusion require- levels reported less compared to sternotomy [8,21,28,32]
ments with a minimally invasive approach, compared to andbothstudiesreportingtimetoreturntonormalactivities
conventional surgery [8,23,25] whilst the others showed no noted a significant advantage for a minimally invasive
difference [6,12,14,19,21,26,32]. Too few studies met the approach [8,21]. In a nonrandomized study, Walther et al.
inclusioncriteriaformeta-analysis(percenttransfused,two reportedequivalentpainforthefirsttwopostoperativedays
studies;unitstransfused,threestudies).Inpatients70yearsor when a minithoracotomy approach was compared to
older,Grossietal.reportedreducedplasmatransfusionswitha sternotomy with a subsequent significant reduction of pain
minimally invasive (n=111) compared to a conventional in the MI group from day 3 onwards, a difference which
(n=259) approach [23]. However, the minimally invasive progressivelywidenedwithtime[32].Betterstabilityofthe
cohorthadalowerpreoperativeriskprofile(e.g.fewerredo bonythoraxledtoearliermobilizationandafasterreturnto
operations), and there was no attempt to adjust for this activitiesofdailyliving.Glowerreportedthatpostoperative
baselinedifferenceintheanalysis.Moreconvincingevidence paintendedtoresolvemorequicklywithaminimallyinvasive
camefromasubsequentstudybythesamegroupthatshowed approachandthatthesepatientsreturnedtonormalactivity
13%fewertotaltransfusionswith1.8fewerunitsofredblood 5weeksmorerapidlythanthosehavingamediansternotomy
cellsusingaminithoracotomycomparedtoasternotomy[25]. (4(cid:5)2 weeks vs 9(cid:5)1 weeks, p=0.01) [21]. Cohn’s data is
SimilardatafromCohnetal.confirmthatpatientsundergoing concordantwithlesspaininhospitalandafterdischarge,less
minimallyinvasivevalvesurgeryaretransfused1.8unitsless analgesicusage,greaterpatientsatisfactionandareturnto
comparedtoaconventionalcohort[8]. normalactivity4.8weeksaheadofsternotomypatients[8].
Two of seven studies [12,14] demonstrated a reduced Vanermenreportedthat94%ofhispatientsreportnoormild
needforreoperationforbleedingwithaminimallyinvasive postoperative pain, 99.3% feel they have an aesthetically
approach [18,19,23,24,26]. Five studies met the inclusion pleasingscar,93%wouldchoosethesameprocedureagainif
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948 P.Modietal./EuropeanJournalofCardio-thoracicSurgery34(2008)943—952
Table3
Mostrecentobservationalcohortstudiesofminimallyinvasivemitralvalvesurgery
Study,year,reference Institution/City Period Noofpatients Mortality(%) Stroke(%)
MVP(%) MVR(%) MVP(%) MVR(%)
Gloweretal.(2000)[33] PAIR 7/97—8/99 1059 1.6 5.5 2.6 2.8
Grossietal.(2002)[37] NYU 11/95—11/01 714 1.1 5.8 2.9 —
Solteszetal.(2007)[1]a Brigham 7/96—2007 663 0.5 3.1 1 —
Chitwoodetal.(2007)b ECU 5/96—9/07 535 2.0 3.8 1.5 1.5
Casselmanetal.(2003)[34] Aalst 2/97—4/02 306 0.4 2.5 0.4 0
Cosgroveetal.(2003)[38] Cleveland 1996—2002 1427 0.3 — 1.8 —
Waltheretal.(2004)[39] Leipzig 6/96—2004 1000 3.9 — 4.3 —
Mishraetal.(2005)[40] NewDelhi 9/97—12/04 430 0.5 — 0.5 —
Aybeketal.(2006)[41] Frankfurt 7/97—5/04 241 3.3 — 0.8 —
Torraccaetal.(2006)[42] Milan 10/99—12/03 104 0 — 0 —
ECU,EastCarolinaUniversity;MVP,mitralvalverepair;MVR,mitralvalvereplacement;NYU,NewYorkUniversity;PAIR,portaccessinternationalregistry;STS,
SocietyofThoracicSurgeons.
a IncludesdatafromMihaljevicetal.[24].
b Unpublisheddata.
Table4
SummarydataderivedfromabovecohortstudiescomparedtodatafromSTSFall2007report
No.ofpatients No.ofstudies Summarydata(%) STSdata(%)
Mortality Repair 2176 6 1.1 1.5
Replacement 979 5 4.9 5.5
Overall 6253 10 2.0 3.3
Stroke Repair 1226 4 1.6 1.9
Replacement 778 3 2.3 3.2
Overall 6290 10 2.2 2.5
Dataforrepairandreplacementarederivedfromthosestudieswherethesevariablesarereportedindependently.Overalldataarederivedfromallstudies
combined.
theyhadtohaveredosurgeryand46%arebackatworkwithin with 91% being discharged home compared to 67% with
3weeks[34].However,perhapsthemostinsightfulpieceof a conventionalapproach [8,24].
evidence for patient preference of MIMVS comes from two
studiesreportingthatthosewhohavehadaMIapproachas 4.9.Intermediate- andlong-term results
theirsecondprocedureallfeltthattheirrecoverywasmore
rapidandlesspainfulthantheiroriginalsternotomy[14,35]. Comparingaconsecutivecohortof100minithoracotomy
mitralvalveoperationstotheprevious100sternotomymitral
4.8.Hospital stay,costs anddischargedisposition valve procedures, Grossi et al. found comparable 1-year
freedom from reoperation (96.8% vs 94.4%, p=0.38,
Does a more rapid recovery translate into a shorter stay respectively) with similar net improvement in functional
in hospital andtherefore reduced costs? Eight of 14 studies class [20]. Mihaljevic et al. reported significantly better
reported less time in hospital with a MI approach [8,12, actuarialsurvivalat5yearsforminimallyinvasivecompared
14,19,21—29,32]. Only five studies were eligible for meta- to sternotomy patients (95% vs 86%), but this may be
analysisandalthoughthetrendindicatedthistobethecase, explained by a lower risk profile [24]. Many of the cohort
theresultwasnotstatisticallysignificant(350patients,WMD studies are temporally updated results from a few select
(cid:2)0.73, 95% CI (cid:2)1.52 to 0.05, p=0.07) (Fig. 1). Chitwood, high-volume centers such as the Cleveland Clinic, the
Cohn and Cosgrove equated this to a 34%, 20% and 7% cost Brigham and Women’s Hospital, New York University,
saving,respectively[8,12,36].Moreover,thesepatientshad University of Leipzig, OLV Clinic (Aalst, Belgium) and East
fewer requirements for post-hospital rehabilitation, which Carolina University. Therefore, only the most recent data
is a significant advantage in terms of healthcare savings from 10 cohorts with 6479 patients are considered, herein
Table5
Studiesreportinglong-termresultsofminimallyinvasivemitralvalvesurgery
Study,year,reference Institution Survival Freedomfromre-operation
Gulielmosetal.(2000)[43] Dresden 93.5%at3.3years —
Casselmanetal.(2003)[34] Aalst 95.4(cid:5)1.7%at4years 91(cid:5)3.5%at4years
Greelishetal.(2003)[44] Brigham 95%at5years 92%at5years
Waltheretal.(2004)[39] Leipzig 83%at6.8years —
Mishraetal.(2005)[40] NewDelhi 99%at3.2years 99.3%at3.2years
Aybeketal.(2006)[41] Frankfurt 90.7%at6.3years 96.2%at6.3years
Torraccaetal.(2006)[42] Milan 100%at2.3years 95.2%at4years
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P.Modietal./EuropeanJournalofCardio-thoracicSurgery34(2008)943—952 949
(Table 3) [1,33,34,37—42]. The crude unadjusted mortality outcomeswithamini-thoracotomyapproachforreoperative
ratesfortheentirecohortare1.1%formitralvalverepairand mitral and aortic valve surgery [48]. In 71 reoperative
4.9% for mitral valve replacement. The corresponding data mitral valve operations of which 38 were done through a
fromtheSocietyofThoracicSurgeons(STS)Fall2007report minithoracotomy, Bolotin et al. noted no difference in
are1.5%forMVPand5.5%forMVR(Table4).Theneurological mortality or CPB times but significantly reduced intubation
event rates for the entire cohort are lower than STS data. times, blood transfusion and hospital stay with a minimally
With regard to long-term survival, we found seven studies invasive approach [49]. In a retrospective study from Duke
reporting from 100% survival at a mean of 2.3 years to 83% University,patientsundergoingarightmini-thoracotomyfor
at 6.8 years postoperatively (Table 5) [34,39—44]. This redomitralsurgeryhadlowermortality,lessbloodlossand
comparesfavorablyto5-yearsurvivalsof86.4%reportedby fewertransfusionsthanviaaredosternotomyoranantero-
theMayoClinic[45]and82%reportedbytheClevelandClinic lateral thoracotomy [50].
[46].Fivestudiesreportedfreedomfromreoperationranging Vanermen recently reported 80 adults undergoing endo-
from99.3%at3.2yearsto91%at4years[34,40—42,44].The scopic MV and TV reoperative surgery with an operative
longest follow-up was 6.3 years with 96.2% freedom from mortality of 3.8% [51]. There was one intra-operative and
reoperation.AgainthiscomparesfavorablytotheMayoClinic two postoperative strokes. Survival at 1 and 4 years was
data which indicates a risk of reoperation of between 0.5% 93.6(cid:5)2.8%and85.6(cid:5)6.4%respectively,andtherewasone
peryearforisolatedposteriorleafletprolapseto1.64%per latereoperationatfiveyears.AttheUniversityofMichigan,
year forisolated anterior leafletprolapse [45]. Bolling et al. used a 5—10cm right anterior 5th interspace
thoracotomy in 22 patients for reoperative mitral and
tricuspid valve surgery with no 30-day mortality [35].
5.Special situations Patients were weaned from ventilation at a mean of 5h
and received 1.3(cid:5)1 units of blood. There were no re-
5.1.Reoperative surgery explorationsforbleeding.Theimportantmessagefromthis
studywasthatallpatientsinterviewedconsideredthattheir
Thegreatestpotentialbenefitofarightmini-thoracotomy recoverywasmorerapidandlesspainfulthantheiroriginal
istheavoidanceofsternalre-entryandlimiteddissectionof sternotomy.
adhesions,avoidingtheriskofinjurytocardiacstructuresor Onnasch et al. reported 39 patients undergoing redo
patent grafts, and limiting the amount of postoperative mitralvalvesurgerythrougharightminithoracotomywitha
bleeding[47].Thisconsistentlytranslatesintoreducedblood mortality of 5.1% [53]. One patient experienced transient
loss, less transfusions and faster recovery. There are seven hemiplegiaduetomigrationoftheaorticballoonendoclamp.
important studies (three case-control and four cohort) This group concluded that a MI approach offers excellent
describingarightminithoracotomyapproachforreoperative exposureandminimizestheneedformediastinaldissection
valvesurgery[35,48—53]andonedescribingaleftposterior and optimizes patient comfort. Their updated series
approach [54] (Table6). described 97 patients undergoing mitral reoperations since
The case-control studies all demonstrated superiority 1996 with anin-hospital mortality of 5.6% [52].
oftherightmini-thoracotomyversusareoperativesternot- Finally, the New York University group have described
omy. The largest series from Sharony et al. demonstrated a left posterior minithoracotomy approach in 40 patients
equal mortality (5% for isolated mitral operations), fewer in whom a right thoracotomy was precluded, e.g. right
wound infections, less blood product utilization, decreased mastectomy/irradiation[54].Theyconcludedthisapproach
hospitallengthofstay,andslightlymorefavorablemid-term to be a valuable option in complicated reoperative mitral
Table6
Studiesreportingaminithoracotomyapproachforreoperativemitralvalvesurgery
Study,reference Period No.of Valve Design Importantfindings
patients
MI Conv
Sharonyetal.(2006)[48] 1995—2002 161 St337 AV,MV CC Surgicalapproachnotanindependentriskfactorformortality.
However,fewerwoundinfections,lessbloodproducttransfusion
andshorterhospitalstaysforMIgroup
Bolotinetal.(2004)[49] 1/96—6/03 38 St33 MV CC ShorterintubationandLOS,reducedbloodtransfusion
Burfeindetal.(2002)[50] 1985—2001 60 Th37 MV(cid:5)TV CC Lessbleeding,transfusionandmortalitywithminithoracotomy
St155 approach
Casselmanetal.(2007)[51] 12/97—5/06 80 — MV,TV Cohort Observed/expectedmortality,0.24.Four-yearsurvival85.6(cid:5)6.4%.
Onereoperationat5years.99%ofpatientspreferredMIapproach
topriorsternotomy
Vlessisetal.(1998)[35] 12/96—10/97 22 — MV(cid:5)TV Cohort Nomortality,meanventilatorysupport5h,meanblood
orASD transfusion1.3(cid:5)1.0units,meanLOS5.9days.Allfeltlesspain
andfasterrecoverythanpriorsternotomy
Waltheretal.(2006)[52]a 3/97—1996 97 MV Cohort Mortality7.2%comparedtoregistrydataof8.75%.Repairin56%
ASD,atrialseptaldefect;AV,aorticvalve;CC,case-control;Conv,conventional;LOS,lengthofstay;MI,minimallyinvasive;MV,mitralvalve;St,sternotomy;Th,
standardanterolateralrightthoracotomy;TV,tricuspidvalve.
a Updatedresultsfromapreviousstudy[53].
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950 P.Modietal./EuropeanJournalofCardio-thoracicSurgery34(2008)943—952
procedures with acceptable perioperative morbidity and and with fewer complications (reduced bleeding, wound
mortality. problems andfewerfemoral arteryreconstructions) andhe
showed areduction in costs ofdisposables by$2800 [61].
5.2.Lowejection fraction
Previouslyconsideredbymanyasacontraindicationtoa 7.Limitations ofa minimally invasive approach
minimallyinvasiveapproach,Mohrhastreated68patients
havingadilatedcardiomyopathy(EF21(cid:5)8%)withMImitral Clearly,thereisalearningcurveforthesurgeonaswellas
valverepairand11withareplacementwithanoverall8.8% the anesthetists, perfusionists and nursing teams. Mohr
mortality[52].Severepulmonaryhypertensionwaspresent reportedahighmortality(9.8%)inhisearlyportaccesscases,
in45.6%.Postoperatively,6.3%developedrenalfailureand partiallyprocedure-relatedwithtwoof51patientssuffering
7.9%hadlowcardiacoutput.Despitesuccessfulmitralvalve an aortic dissection [13]. After simplification of the surgical
repair, seven patients required transplantation during procedurethemortalitydecreasedto3%.Vanermendemon-
follow-up. stratedthatICUandhospital staysdecreasewithincreasing
experience[62].
5.3.Elderlypatients There are potential vascular risks with femoral cannula-
tion,especiallywiththelargerportaccessfemoralcannula.
Two studies have looked at the application of MI Groinseromascanbeproblematicbutarekepttoaminimum
techniques specifically to elderly patients. Grossi et al. by dissection only of the anterior surface of the vessels as
reviewed111patientsundergoingMIvalvesurgerywhowere wellasclippinglymphatics.Whenthepericardiumisopened
at least 70 years old and compared these to 259 patients too posteriorly, phrenic nerve palsy has been reported and
having a sternotomy [23]. The MI group had a significantly canbeavoidedbyplacingthepericardiotomyatleast 3cm
lowerincidenceofsepsisandwoundcomplications,required anteriortoit.Excesstensionbypericardialretractionsutures
lessfrozenplasmatransfusions,andhadashorterlengthof should be avoided. Although some have suggested that a
hospitalstay.Theyconcludedthatthisapproachcanbeused small anterior thoracotomy is associated with equal or
safelyinoperationsontheelderlypopulationwithexcellent greaterpostoperativepain[63,64],thereisgoodevidenceas
results.Also,Tabataetal.recentlyreported123casesofMI detailed above that it actually reduces postoperative
mitralvalverepairinpatientsaged70yearsandolderwith discomfort andenhances recovery [21,25,65].
1.6%operativemortalityaswellas5-yearactuarialsurvival
of 87%and5-year freedom fromreoperation of93%[55].
8.Conclusions
6.Endo-aortic balloonocclusion versustransthoracic Overthelastdecadethere hasbeenatransformation in
clamping thewaycardiacsurgeons,cardiologistsandpatientsdecide
theapproachtocardiactherapies.Lessinvasiveprocedures
One of the most significant risks of endo-aortic balloon aredemandedbutatthesametimeprovensafety,efficacy
occlusion(EABO)isaorticdissection,andasaconsequence, and durability are expected. There is no prior level one
many surgeons have abandoned this technique. In the first evidence to justify switching to minimally invasive mitral
PAIRreport,theincidenceofaorticdissectionwas1.3%inthe valvesurgery.Allthereviewedevidencedemonstrates that
firsthalfofthestudycomparedto0.2%inthesecondhalf,a minimally invasive mitral valve surgery is associated with
difference attributable to experience, better techniques, equal mortality and neurological events despite longer
and improved technology [56]. In comparison to transthor- cardiopulmonary bypass and aortic cross-clamp times.
acicclamping(TTC),EABOismoreexpensive,andtheclamp However, there is less morbidity in terms of reduced need
position is less stable. Proximal balloon dislodgement can forreoperationforbleeding,atrendtowardsshorterhospital
cause innominate artery occlusion with neurological injury. stay, less pain and faster return to preoperative function
Monitoring by transesophageal echocardiography and trans- levels than conventional sternotomy-based surgery. This
cranial Doppler should be done routinely [57,58]. Balloon wouldbeexpectedtotranslateintoimprovedutilizationof
prolapse into the left ventricle can lead to inferior limitedhealthcareresources.Withfollow-upnowofalmost7
myocardialprotection,ventriculardistensionoraorticvalve years it is clear that long-term outcomes are equivalent to
injury. those of conventional surgery. Data for minimally invasive
There are three pertinent studies, all non-randomized mitralvalvesurgeryafterpreviouscardiacsurgeryislimited
consecutiveseriesfromGermany,demonstratingsuperiority but consistently demonstrates reduced blood loss, fewer
of TTC over EABO. Onnasch et al. demonstrated a signi- transfusions and faster recovery compared to reoperative
ficantlyhigherriskofneurologicalcomplicationswithEABO sternotomy. Almost all patients who undergo a minimally
(8.1%vs1.8%,p<0.05)andhighermortality(5.2%vs3.1%, invasive mitral valve operation as their second procedure
respectively). Mohr subsequently abandoned EABO for feeltheirrecoveryismorerapidandlesspainfulthantheir
primary mitral valve procedures [59]. In58patients, Aybek original sternotomy.
et al. demonstrated similar results with faster operations, Asforthefuture,minimallyinvasivecardiacsurgeryislikely
fewer technical difficulties, less blood loss and lower costs tobecomemorewidelyadoptedasgrowthinthisnichemarket
using the transthoracic clamp [60]. Reichenspurner et al. andcardiacsurgeryasawholeisoftenpatient-driven,muchin
confirmed shorter operative times with TTC in 120 patients thesamewaythatpercutaneousinterventionformultivessel
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P.Modietal./EuropeanJournalofCardio-thoracicSurgery34(2008)943—952 951
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