Northern Medical Journat 2OO9: 1g(1): 1_9

ON PUMP BEATING HEART CABG ISSUPERIOR TO CONVENTIONAL CABG INPOOR LEFT VENTRICULAR FUNCTION

Hriday Ranjan Royr, Mirza Md. Nazrur rsram2,. Nasir Uddin Ahmed3,Rabindra Nath Barmana

Abstract:3cronary artery bypass graft (CABG) surgery is one of the treatment modalities of coronary arteryc sease (cAD) patients. There are multiple selection criteria for cABG

""; ;;lte1" procedures tikeconventional CABG, on pump beating heart CABG 3nd9f] pump beating hearr cnbc topcAB). Thisstlrdy was intended to compare between conventional CABG'and on-pump oeating heart CABG.Total 60 patients were selected for the study, of whicl'L so fatients rr'ao ,inJ"rgone conventionalCABG and 30 had undergone on pump- beating heart' CABG. D;f";";i -pieoperalve andpostoperative variables shows clear and significant_su[eriority of on pump beating [""rt cnac. So itmay an alternative surgical procedure where oPOAB is not feasible in poor ieft ventricular (LV)

f unction. Northern Medical Journat 2009; 1g(1): 1_9.

lndexing words: coronary Artery Bypass Graft (oABG), coronary Artery Disease (cAD), on-pumpbeating heart OABG (on P-BH OABG), off pump beating heart CABG (opcnei baroioputmonarybypass (CPB).

lntroduction:

coronary Artery Bypass Graft (OABG) surgery is excision with saphenous vein or internalwell esiablished treatment modalities in pitients r"rnr"ry "rt"rv*'g-iIii.i" ri l tirr, reportedwith Coronary Artery Diseases (CAD) refractory successfut CABd opieration took place in 1964 into .medical therapy or when intervention Leningrad, *h"r" Kolesov grafted a LIMA to thecardiologic procedures (prcA) are not feasible.l mo riitnout cBp t Yr q*vv

After 1968, CABG with Cardiopulmonary Bypass(CPB) was widely adopted and has become weil-established treatment modalities for patients withCAD5. However, there has been increasingevidence that CPB may be responsible for someof the morbidities associated with CABG surgery.Thus, it has been proposed that CABG suroervwould be safer if CpB would be avoided.o inedevelopment of new cardiac stabilization deviceshas allowed for the creation of safe andreproducible anastomoses on beating heart.T

ln '1950s, before the Cardiopulmonary Bypass(CPB) era, the concept of myocardialrevascularization was propounded byDemikhov.2 ln the same decade, Murray andLongmire performed CABG using segmental

Consultant Dept. of Surgery &Assoc. Prof. Dept. of Cardiology,Bangpur Medical CollegeProf . of Cardiac Surgery

1

2.

3.

NICVD, Dhaka4. Junior Consultant, Cardiology

Pirganj lJpazila Health Complex, Rangpur.

Several large, nonrandomized, retrospectivecase series comparing CABG surgery performedon the beating heart (Off PumP) and

conventional CABG (CCAB) surgery performedwith CPB (on pump) have indicated an

advantage to CABG surgery without CPB(OPCAB); however, selection bias towardstbwer-rlsi< cases in OPCAB remains an issue.6

Furthermore, the potential pitfalls of OPCABsurgery are technically demanding with steeplearning, incomplete revascularization,intraoperative, ischemia and sub-optimalanastomoses.-Enormous development of medical therapy andintervention cardiology resulted to reducednumber of CABG and the end stage coronaryartery diseases (ESCAD) are being submitted forCABG surgery.ESCAD patients with bypassable vessels to twoor more regions of reversible ischemia canundergo safe CABG with acceptable hospitalsurvival and mortality and morbidity' ln high-riskESCAD patients, who may poorly toleratecardioplegic arrest, on-pump beating heart (OnP-

BH) CABG may be an acceptable alternativeassociated with lower postoperative mortalityand morbidity. Such a technique offers bettermyocardial and renal protections a,ssociated with

lower postoperative complications.'' o

Furthermore, in high-risk patients (Poor LV

function-EF <25o/", evolving Ml or infarct and

advanced age-mean 79.5) OPCAB is not

technically feasible. So, an intermediateapproach based on maintenance of beatingheart with CPB support but without aortic crossclumping and cardiologic arrest might be an

acceptable alternative.e lt is still associated with

the potentially detrimental effects of CPB but

eliminates intraoperative global myocardialischemia due to avoidance of cross-clumpingand cardiologic arrest.e'

1o

The special emphasis may be projected to CADwith poor LV function (EF <35%). OnP-BH

Roy, lslam, Ahmed, Barman

CABG can be done safely in patients with a lowejection fraction.ll'12't' The main advantage o{

OnP-BH technique is the ability it provides one toperform complete revascularization andintracavity _procedures with low morbidity and

mortality. ''"" lt avoids myocardial injuryassociated with aortic cross clamping in

conventional CABG (CCAB).12ln Bangladesh, several studies were conductedreoardino the outcome of conventionalt[t6ta'Ys't0 but no previous study on OnP-BHCABG surgery has been carried out till date. Weintroduced it first time in NICVD. So, it will bebeneficial to evaluate the efficacy, safety andapplicability of OnP-BH CABG surgery in

patients with CAD having impaired LV function.Our study was to identify the CABG procedurethat is better for patients with impaired left

ventricular {unction.Materials and Methods:The study was conducted at National lnstitute of

Cardiovascular Diseases; Dhaka during theperiod may 2006 to April 2007. lt was aProspective Randomized Control Clinical Trial(RCT) type o{ study. Patients undergoing CABGfor CAD with impaired left ventricular function(EF < 45%) were selected for the study. Total 60patients were selected for the study and werebeing divided into two groups: Group l: 30patients underwent Conventional CABG (Controlgroup) and Group ll: 30 patients underwent On-

Pump Beating Heart CABG (Study group). Thepatients were explained about the purpose and

importance of the study. lnformed and writtenconsent was taken f rom the participants.lnclusion criteria was patients underwent on-pump beating heart CABG & conventional CABGhaving CAD with impaired leit ventricularfunction (EF <45%). Exclusion criteria werepatients having EF >45%, history of previous

cardiac surgery, concomitant proceduresincluding valvular operation, congenital orventricular aneurysm, reoperation and had

On pump beating heart CABG is superlorto conventional CABG in poor leftventricular function

history of renal, respiratory or hepatic failure,strokeff lA or coagulopathy.Peroperative variables were Total operation timein minutes, Extracorporeal circulation time inminutes, Aortic cross-clamp time in minutes(CCAB), Number of distal anastomoses (LAD,LCX, Diagonal, RCA), Postoperative Ml,Ventilation time in hours, ICU stay in hours, Lowcardiac output syndrome, Total length of hospitalstay in days, Neurological complications,Mortality etc. Assessment of LV function at 3'dmonth by Echo was done in each patient.Patients were followed up for 3 months. Allpatients were attended '1 month after dischargeand at 3 months following operation. All relevantdata was collected from each patient by apredesigned q uestionnaire.

Result:The mean age was found 62+7 in group-l and57x.l1 in group-ll (Table-1). The value ofunpaired t-test was 1.67 and it was insignificant(prO.1). So there was no age variation betweentwo groups. The Chi-Square test of thepreoperative data between two groups was 0.58with df (c-1) (r-1) =1 (Table-2). The p value was>0.5 and was insignificant. So there was nodifference of preoperative data between twogroups. The mean operation time in group-l was276!20.24 minutes and in group-ll was227x.15.85 minutes (Table-3). The unpaired t-test value is 10.65 (p<0.001) and was highlysignificant. So, the total operation time wassignificantly less in group-ll than in group-1. TheMean Extracorporeal Circulation Time was '126.4+ 12.3 min in Group-l and 107-+4.5 min in Group-.ll (Table-a). Unpaired t-test value was 1.48(pt0.1) and was insignif icant. So theExtracorporeal Circulation Time had nodifference between two Groups. The mean XCTin Group-l was 6'1 .3 * 4.42 (Table-S). As therewas no Cross Clamp in Group-ll, it was 0. Theunpaired t-test value was 13.8 (p<0.001) and

was highly significant. Table-6 shows the BypassGraft conduits of two Groups. The X2 test revealsp value>0.5 and was insignificant. So GraftConduits are not predictor variables between twoGroups. Table-7 shows the name and number ofdistal anastomosis. The Mean DistalAnastomosis in Group-l was 2.7 + 1.2 and inGroup-ll was 3.1 * 1.3. The unpaired t{est wasdone with l= 0.22 (ptO.t) and insignificant. Sothe numbers of distal anastomosis did not varysignificantly between two Groups. Table-g showspostoperative predictor variables as follows: ICUStay in Hours: G-l Mean=67.32+5.4, G-llMean=35.2+4.8, t=4.44(p<0.05), significant;Ventilation Time in Hours: G-l Mean=18.2t3.5,G-ll Mean='1 0.2*2.4, t=1.99(p<0.05), Signif icant;Postoperative Ml: X2 = 0.22(p>.05), lnsignificant;Blood Loss in ml: G-l=625.54 ti0.42, G-ll=630.4+8.7, t=0.38(ptQ.1), lnsignificant;Arrhythmia: G-l=13(43%), G-ll=5('16%), X' =3.78(p<0.05), Significant; tnotropic Support inHours: G-l=62.8+6.4, G-ll=30.6*4.7,t=4.05(p<0.00'l), Significant; Low cardia! outputsyndrome: G-l=S1367;, G-ll=3(10%), X' = 3.74(p=0.0S), Significant; Respiratory Complications:G1=7123"7.1, G-ll= 6(20%), p>0.01 with X2 test,lnsignificant; Renal Complications: G-l=4('13%),Gll=216"7"1, ptO.1 with y2 test, lnsignificant;Neurological Complications: G-l=9(30%), G-ll=2(6%), X' =5.44(p<0. 02), Sign if icant; Mortal ity:G-l= 2(6%), G-ll= 1(3%), p>0.5 with y2 test,lnsignificant. So the significant difference wasobserved in ICU stay, Ventilation time,Development of Arrhythmia, lnotropic support,Low output syndrome and Neurologicalcomplications. No significant difference found inPostoperative Ml, Blood loss, Respiratorycomplications and Mortality between two groups.Table-9 shows LVEF lmprovement between twogroups. The Unpaired t-test value2.47(p<0.02) and was significant. So,improvement of LVEF in Group-ll wassignificant than in Group-1.

wasthe

more

41-5051-6061-70

72313 4310 33

5 1618 60723

50

30

71310

000

Roy, lslam, Ahmed, Barman

>0.1

t= '13.8

p<0.00'1

Mean+SD

HTN

DM

CreatinineLevel>2mgldl

Family History

SmokingHistory

Mean+SE

40-8461.3 r 4.42

18 60

11 36

15

I1

>0,5

>0.5

>0.5

>0.5

>0.5

02 LIMA 30(100%) 30(100%) p>0.5RIMA O 1(3%) with X2RA 1(3%) 1(3%) test.

Range in 230-370 180-295 t- Test=minutes 10.65.

Meanr SE 276*20.24 227t15.85 p<0'001

RSVG 30(100%) 30(100%)

The values are numbers with percentage withinparenthesis.

LIMA= Left lnternal Mammary Artery; RIMA=Right lnternal Mammary Artery; RA= RadialArtery; RSVG= Reverse Saphenous Vein Graft.

Table-7: Numbers of Distal Anastomosis.

Target Vessel value30(100%)11(36%)17(56%)

1(3%)

14(46%)

e(30%)Total

7 23 't1 36

21 70 22 73

LAD

DiagonalOM

RI

RCA

PDA

30(100%)13(43%)27(e0%)

1(3%)

14(46%)

11(36%)

Unpairedt= 0.22,p>0.1

RangeMean +

SE

80-220126.412.3

60-'175 t= 1.48+ 107 + 4.5 p>0.1 9582

Table-l: Age and Sex Distribution.

AgeGroup-l(30) Group-l(30)

p valueMale Female TotalMale Female Total

No o//o No o//o

Table'2: Preoperative Data.

VariablesGroup-l Group-ll

p valueNo o/to No ot/o

Table-S: Aortic Cross Clamp Time (XCT) in minutes.

Range

Table-6: Bypass Graft Conduits.

Table-3: Total Operation Time.

Table-4: Extracorporeal Circulation Time (ECCT).

Mean t SE 2.7 * 1.2 3.'1 t 1.3

-; ,:. -E'-q

_=: : ii _-=_: s:_:g-:'

*11= *i- r-::-:. Jescending; OM= Obtuse":': --= - = ='--:-..rS lntermediUS; RCA= Right_ -- -- =-" :li-, -{JA= posterior Descending-?,

-$bie-€ ::s::cerative Predictor Variables in lCU.

The late in hospital complications of woundinfections (20% and 13%), totat tength of hospitatglqy (16+7 days and '14-16 days) and mortatiry(00%) was statistically insignificant between twogroups (Table-10).

Table-10: Late in Hospital Complications.

l=4.44p<0.05

t=1.88p<0.05

x2= 0.22p>.05

t=0.38p>0.1

X2 =378p<0.05

t=4.05p<0,001

x2 = 3]4P=0.05

p>0.01 with

x2 test

p>0.1 with X2

test

X2 =5.44p<0.02

p>0.5 with X2test

The values are numbers with percentage withinparenthesis.

Table-9: lmprovement of LV Function (LVEF)between Groups.

67.32t5.4 35.2t4.8

18.2t3.5 10.2x2.4

3(10%) 2$a/")

625,54 630.4 8.7x10.42

13(430/.) 5(16%)

62.8t6.4 30.6x4.7

e(30%) 3(10%)

7(23o/o) 6(20%)

4(13o/o) 2(6"/0

Wound lnfeclion 6(20"/")(Affecled)

4(13"/4 X2 test revealsp>0.5,

lnsignificant

HospitalStay(days) 16x.7 14+6Mean t SE

Mortality (n) 0 O

t-test, p>0.01,insignificant.

lnsignificant

s30

31-35

36-40

41-45

>46

omplications 9(30%) 2(6%)

2(6'/4 1(3%)

The values are numbers with percentage withinparenthesis.

Discussion:

This study included total 60 patients of coronaryartery diseases with LVEF< 1% who underwentCABG surgery in NICVD, Dhaka, Bangladesh.Out of 60 patients, 30 underwent convintionalIABG (Group-t) and 30 underwent On pumpBeating Heart (OnP-BH) CABG (Group-il). Datafrom 60 patients were included for final analysis.The mean age was found 62+7 in group-l and57+'l 1 ;n group-ll and no significant variation ofage between two groups. Age of the maioritv ofpatients was 51 to 60. ln another studyt3,-themean patient age was 57.9 + 9.5 and was similarto this study. There was only one female patientin G-l (3%) in our series. ln another studylo themale to female ratio was 22:1. The seleciion ofLVEFS45 may be the cause of having minimalfemale patients in this series

The mean operation time (minutes) in group_lwas 276i20.24 and in group-il was 227ti5.85.The total operation time was significanily less ingrgup-ll than in group-1. ln the study of Gulcan etal ", the total operation time was 225 + 63 min.This was similar to Group- l. So, total operationtime was reduced significanfly in Group-ll. The

1

5

6

10

8

0

0

4

7

19

Unpairedl= 2.47,p<0.02,

Significant

Mean Extracorporeal Circulation Time (ECCT orCPB time) was 126.4 r 12.3 min in Group-l and10h4.5 min in Group-ll. The difference betweentwo groups was insignificant. ln another study 7

CPB time was '116120 min and was similar tothis study. The mean XCT (Cross clamp time) inGroup-l was 61 .3 t 4.42. As there was no CrossClamp in Group-ll, and it was 0. The unpaired t-test value was '13.8 (p<0.001) and was highlysignificant. The XCT was 84+23 min in the studycarried out by Prifti et al8 and 64.2+26.2 min inthe study of Folliguet et all2 and was nearlysimilar to this study.

The Bypass Graft conduits of two Groups wereas follows: in G-|, LIMA 100%, RIMA 0%, RadialArtery 3% and RSVG 100% and in G-ll, LIMA100o/o, RIMA 3%, RA 3% and RSVG 100%. GraftConduits are not predictor variables between twoGroups. ln other studyl3, LIMA use was 97.87",RA 21"/" and RSVG 84.8% and was nearlysimilar to our study. The Mean number of DistalAnastomosis in Group-l was 2.7 + 1.2 and inGroup-ll was 3.1 + 1.3. The target vessel in G-lwere LAD 100%, Diagonal 36/", Obtusemarginal 56%, Ramous lntermedius 3%, RCA46% and PDA 30%. ln G-ll, the target vesselwere LAD 100%, Diagonal 13"/", ObtuseMarginal 27"k, Ramous lntermedius 3%, RCA46% and PDA 36%. The number of distalanastomosis did not vary significantly betweentwo Groups. The number of distal anastomosiswas 2.6+0.97 and 3.06 * '1.0413 in other studies.ln the study of Gulcan et all3 the target vesselwas: LAD 93.1%, Diagonal 60.8%, OM 76.1%and RCA 73.9%. The number and target vesselof our study was similar to other study.

ICU Stay in Hours: G-l Mean=67.32t5.4, G1lMean=35.2+4.8 was significantly less in G-ll. lnanother studyls ICU stay was 2.56*1.7 days andwas similar to this study. Ventilation Time inHours: G-l Mean=18.2t3.5, G-ll Mean=10.2t2.4and was significantly less in G-ll. Ventilation time

was 9.2 *.22.6 in another studyl2 and was similarto the Group-ll of this study. Postoperative Mt:1O% in G-land 6% in G-ll and the difference wasinsignificant. Perioperative Ml were 2.8/o 17and'1.3%" in otherstudies. The rate of Ml is relativelyhigher in Group-l of this study. Blood Loss in mt(Postoperative): G-l=625.54 x.10.42, G-ll=630.4*8.7, t=0.38(p>0.1) and the variationwas insignificant. ln other studies it was500.15t303.55m113 and 61 4*22.6m112 . Thesefindings are similar to our study. PostoperativeArrhythmia: G-l= 43o/", G-ll= 16% and it wassignificantly^less in G-ll. Arrhythmia was 19.1o/o17and 15.2o/"'' in other studies. These findings aresimilar to the Group-ll of our study and signifythat the rate of arrhythmia is higher in Group-|.Postoperative lnotropic Support in Hours in ICU:G-l=62.8+6.4, G-ll=30.6+4.7 and wassignificantly less in G-ll. lnotropic support was19.2 hours in the study of Legare et al6.Postoperative Low output syndrome: G-l=30%,G-ll=10% and was significantly less in G-ll. lnthe study of Prifti et al' it was 24"k and ii%respectively. Postoperative RespiratoryComplications: G-l=23%, G-ll= 20"/" and thedifference between two Groups was insignificant.ln the study of Prifti et al' respiratorycomplications were 3.7%. The higher incidenceof respiratory complications in this study was dueto inadequate isolation and poor restriction ofvisitors in the lCU. Postoperative RenalComplications: G-l=1 3%, G-ll=6/. the differencewas statistically insignif icant. Renalcomplications were 2.2o/o13 and ',l3.3% 10 in otherstudy and are similar to this study. Acute renalfailure was found in 3.6% to and 3.5o/" 17

oIpatients undergoing CABG with poor LV

Roy, lslam, Ahmed, Barman

f unction. Postoperative NeurologicalComplications: G-l=30%, G-ll=6% and wassignificantly less in G-ll. ln another study 7, theneurological complications were 8.4./" and 7.5"/"respectively. The incidence was similar toGroup-ll of this study but there are higher rate of

On pump beating heart CABG is superiorto conventional CABG in poor leftventricular function

-g.1sloglcat complications in Group_1. ICUil,lor":a fty: G-l= 67., G-ll= 3% and was statisticallv-s gr:rficant. Hospital mortality was 2oA t, andI -".' in other study. The rate of mortality was

s - ra!'rn our study.

So the significant difference was observed inICU stay, Ventilation time, Development ofArrlrythmia, lnotropic support, Low outputsyndrome and Neurological complications.These parameters are significanily less inGroup-ll and favors Onp-BH CABG thanConventional CABG in patients with poor LVfunction (LVEF<45). No significant differencefound in Postoperative Ml, Blood loss,Respiratory complications and Mortality betweentwo groups.

The late in hospital complications of woundinfections (20% and 13%), total tength of hospital

g]?y (16+7 days and 14+6 days) and mortatity(00%) was statistically insignificant between twogroups (Table-10).

ln the study of Folliguet et a|12, hospital stay was9.4t5.8 days. A wound infection was g% in thestudy of Prifti et al7 . These findings were nearlysimilar to our study.

Pre- and postoperative EF analysis withimprovement of LVEF was statistically significantin both group-l and G-ll. The numbers ofSubgroup Migration (LVEF lmprovement) inGroup-ll was significanily more than in Group_1.ln Group-1, the , mean preoperative andpostoperative (at 3'd month) LVEF were 39.gtj.2and 42.9 + 1.7 respectively. ln Group_ll, themean preoperative and postoperative LVEFwere 4'1.6+1.3 and 46.26 +- 2.01 respectively andwas significant statistically at p>0.05 level.

Prifti et al.'

Prifti et al.8

24.8+4

24.8*A.4

26.4*4

27.2t40.035 26.2t 4.3

0.001 25$27+6 NS

26.6+7 0.125Folligurt et a|.12 24.9% *.11.2%Gulcan et a1.13 25.6*2.g

30.5%t10.8% 0.003.

33.64r4.69

Table-11: lmprovement of LVEF in different previous studies.

StudyOnP-BH CABG Conventional CABG

pPreoperative Postoperative p Preoperative Postoperative

Table-1'1 shows the preoperative andpostoperative LVEF in different previous studiesundergolng CABG. From these table values, itcan be realized that the LVEF had improvedsignificantly in the patients undergoing Onp-BHCABG than conventional CABG in paiients withpoor LV functton, Our study also showed thatsignificant improvement of LV function can beachieved by using Onp-BH CABG in .patientswith poor LV function.

Several limitations of this study should beaddressed. First, Echocardiography is an

observer dependent investigation and it waspossible for an observer to distinguish betweentwo groups. So there may be chance ofbiasness. Second, all surgery were notperformed by one surgical team but sameprotocol of NICVD was followed by allteams.Conclusion:

On-pump beating-heart (Onp-BH) CABG is safefor patients with severely depressed LV function.The OnP-BH technique offers surgeonscomplete revascularization without technicil and

hemodynamic difficulties along with lowmorbidity and mortality. ln highest risk patients,who may poorly tolerate cardioplegic arrest, andin situations where off pump surgery mayincrease the operative risk, the on-pump/beating-heart CABG may be an acceptable alternativeassociated with lower postoperative mortalityand morbidity. Such a technique offers bettermyocardial and renal protection associated withlower postoperative complications resulting fromintraoperative hypoperfusion. LV function hadalso improved significantly after surgery. Thesebenefits suggest that OnP-BH CABG should bethe method used in cases of severe LVdysf unction.

List of Abbreviations:

CABG- Coronary Artery Bypass Graft, OPCAB-Off-Pump Coronary Artery Bypass, CCAB-Conventional Coronary Artery Bypass, OnP-BH-On-Pump Beating Heart, CAD- Coronary ArteryDiseases, CPB- Cardiopulmonary Bypass,PTCA- Percutaneous Coronary Angioplasty,IMA- lnternal Mammary Artery, LMCA- Left MainCoronary Artery, LAD- Left Anterior Descending,LCX- Left Circumflex Artery, RCA- RightCoronary Artery, OM- Obtuse Marginal, l-V- LeftVentricle, EF- Ejection Fraction, LVIDd- LeftVentricular lnternal Diameter in Diastole, LVIDs-Leit Ventricular lnternal Diameter in Systole,ESCAD- End Stage Coronary Artery Diseases,VSD- Ventricular Septal Defect.

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I