sternal wound infection after heart

8/8/2019 Sternal Wound Infection After Heart

1/5

Sternal Wound Infection After HeartTransplantation: Incidence and Results With

Aggressive Surgical TreatmentMichel Carrier, MD, Louis P. Perrault, MD, Michel Pellerin, MD,Richard Marchand, MD, Pierre Auger, MD, Guy B. Pelletier, MD, Michel White, MD,Normand Racine, MD, and Denis Bouchard, MD

Department of Surgery and Medicine and the Microbiology Laboratory, Montreal Heart Institute and University of Montreal,Montreal, Quebec, Canada

Background. Sternal wound infection remains a signif-icant complication. We reviewed the incidence and thetreatment of sternal wound infection after hearttransplantation.Methods. Of 226 patients who had a heart transplanta-

tion, 20 (8.8%) underwent postoperative wound debride-ment for superficial or deep sternal wound infection. Theincidence and the survival of patients with sternalwound infection were analyzed.Results. The incidence of sternal wound infection was

similar among patients treated with four protocols ofimmunosuppressive drugs: cyclosporine and prednisone(0 of 22; 0%); cyclosporine, prednisone, and azathioprine(2 of 24; 8.3%); cyclosporine, prednisone, azathioprine,and antithymocyte globulin (15 of 139; 10.8%); and cyclo-

sporine, prednisone, mycophenolate mofetil, and anti-thymocyte globulin (3 of 41; 7.3%) (p 0.4). Six-monthand 5-year survival of patients with sternal wound infec-tion averaged 85% 8% and 74% 10% compared with92% 2% and 82% 3% in patients without woundinfection (p 0.15). Patients with deep sternal woundinfection, debridement, and reconstruction had a 5-yearsurvival averaging 80% 10%.Conclusions. The incidence of sternal wound infection

remains similar between patients treated with the tripledrug therapy. Surgical debridement and reconstructioncan result in long-term survival after heart transplanta-tion.

(Ann Thorac Surg 2001;72:71924) 2001 by The Society of Thoracic Surgeons

Sternal wound infection remains a serious complica-tion after cardiac operations, with rates ranging from1% to 10% [14]. Although most wound infection epi-sodes are superficial and self limited, deep sternal infec-tion and acute mediastinitis can be life-threatening, es-pecially in heart transplantation recipients to whomimmunosuppressive agents are administered during thepostoperative period. Not only was sternal wound infec-tion not reported in the most recent clinical trials com-paring newer immunosuppression agents after hearttransplantation [5, 6], but the incidence of wound infec-tion was almost never analyzed in single-center studies

on clinical results after heart transplantation. Yet, sternalwound infection is a major cause of morbidity andoccasionally of mortality among these patients.

The objective of the present study was to review thevariation in the incidence of sternal wound infectionaccording to different protocols of immunosuppressivedrugs immediately after heart transplantation. The clin-ical outcome of sternal wound infection treatment afterheart transplantation was also reviewed.

Material and Methods

Heart Transplantation Program

From 1983 to September 2000, 237 patients underwentheart transplantation at the Montreal Heart Institute.Eleven patients died during or immediately after theirsurgical procedures, precluding any significant analysisof the risk of wound infection. All patients were followedprospectively and data were collected in a computerizeddatabase. Four protocols of immunosuppressive agentswere used during the study period. Cyclosporine andprednisone were administered to patients who under-

went heart transplantation between 1983 and 1987. Cy-closporine, prednisone, and azathioprine were used in1988; the combination of cyclosporine, prednisone, aza-thioprine, and rabbit antithymocyte globulin from 1989 to1997; and cyclosporine, prednisone, mycophenolatemofetil, and antithymocyte globulin was used from 1997to 2000 [7, 8].

Patients who underwent open heart operations be-tween 1983 and 2000 were administered preoperative andpostoperative antibiotic prophylaxis with either cefazolinor vancomycin for penicillin-allergic patients. The anti-biotics were administered during the first 48 hours afteroperation in heart transplantation patients.

Accepted for publication May 3, 2001.

Address reprint requests to Dr Carrier, Department of Surgery, MontrealHeart Institute, 5000 Belanger St East, Montreal, QB, H1T 1C8, Canada;e-mail: [email protected].

2001 by The Society of Thoracic Surgeons 0003-4975/01/$20.00Published by Elsevier Science Inc PII S0003-4975(01)02824-7


2/5

Definition of the Type of Infection

Sternal wound infection was classified as superficialinfection characterized by purulent drainage from thewound limited to cutaneous and subcutaneous involve-ment. Deep wound infection involved deep fascial andmuscular tissue. Acute mediastinitis was defined as pu-

rulent drainage involving the sternal bone and surround-ing mediastinal tissue. Cultures of drainage of all sus-pected surgical wound infections were obtained andanalyzed routinely.

Statistical Analysis

Data are expressed in mean and standard deviation.Differences between means were analyzed with the Stu-dents t test, and the Fisher exact test was used forcategorical variables. The actuarial method was used toanalyze survival and event-free survival in our groups ofpatients. A logistic regression analysis was used to studythe risk factors correlated with wound infection after

heart transplantation. Factors included in the analysiswere recipient age, sex, pretransplant diabetes, mechan-ical support before transplantation, and the protocols ofimmunosuppressive drugs.

Results

Patient Population

Among 226 patients who had a heart transplantation,preoperative diagnoses included 118 (52%) with end-stage ischemic cardiomyopathy, 50 (22%) with congestivecardiomyopathy, and 38 (17%) with various forms ofend-stage heart disease. Of the 226 patients, 20 (8.8%)showed evidence of sternal wound infection: 9 (of 226;3.9%) had superficial wound infections, 4 (of 226; 1.8%)had deep wound infections, and 7 (of 226; 3%) had acutemediastinitis. Of these 20 patients, 3 (15%) were womenand 17 (85%) were men; of the 206 free from sternalinfection, 37 (18%) were women and 169 (82%) were men(p 0.7). Patients with sternal wound infection averaged52 9 years of age compared with 46 10 years inpatients free from sternal infection (p 0.01). Diabeteswas noted in 1 of the 20 patients (5%) who developed asternal wound infection and in 12 of 206 patients (6%)without wound infection after transplantation (p 0.9).

Superficial wound infections were treated with localdebridement and dressing changes in an outpatient

clinic. Deep wound infections were treated with surgicaldebridement and sternal rewiring including Robiscekweave in 3 patients and local debridement in anotherpatient. Acute mediastinitis was treated with surgicaldebridement, drainage, and sternal rewiring in 5 pa-tients. Omentoplasty and pectoralis muscle flaps wereused in 2 other patients.

Sixteen patients (of 20; 80%) who developed sternalwound infections after transplantation were followed atour outpatient clinic while waiting for heart transplanta-tion (recipient UNOS status 2) compared with 116 (of 206;56%) UNOS status 2 recipients without wound infectionafter transplantation. Four patients (of 20; 20%) with

sternal wound infection after transplantation were hos-pitalized before transplantation (recipient UNOS status1) compared with 89 (of 206; 43%) UNOS status 2 recip-ients who remained free from wound infection aftertransplantation.

Twenty-five patients were mechanically supported be-

fore heart transplantation, 5 with the CardioWest totalartificial heart, 3 with a Thoratec (Pleasanton, CA) leftventricular assistance, and 17 with an intraaortic balloonpump. All other mechanically supported patients did notshow any evidence of sternal infection throughout theperiods of support and transplantation. One patient (of20; 5%) was on mechanical assistance with the Cardio-West (Tucson, AZ) total artificial heart and developed anepisode of acute mediastinitis after heart transplantation.

Patients who developed sternal wound infection aftertransplantation waited 15 23 weeks for a donor heartcompared with 24 38 weeks for patients who did notshow any evidence of wound infection after transplanta-tion (p 0.13). Donor ischemic time in these two groupsaveraged 139 49 minutes and 134 63 minutes,respectively (p 0.5).

Sternal Wound Infection and Regimens of Immunosuppressive Drugs

There was no sternal wound infection among the 22patients treated with cyclosporine and prednisone. Evi-dence of sternal wound infection after heart transplanta-tion was found in 2 of 24 (8.3%) patients who wereadministered cyclosporine, prednisone, and azathio-prine; 15 of 139 patients (10.8%) who were administeredcyclosporine, prednisone, azathioprine, and antithymo-cyte globulin; and 3 of 41 patients (7.3%) who were

administered cyclosporine, prednisone, mycophenolatemofetil, and antithymocyte globulin (p 0.4).

Of the 20 sternal wound infections after heart trans-plantation, most were superficial (9; 45%), 4 (20%) weredeep, and 7 (35%) were episodes of acute mediastinitis.The acute mediastinitis was caused by various bacterialagents in various combinations: bacteroides (n 1),Escherichia coli (n 2), Staphylococcus epidermidis (n 5),Staphylococcus aureus (n 6), methicillin-resistant S au-reus (n 2), Aspergillus fumigans (n 1). For superficialand deep wound infections, S aureus (8 of 20; 40%) and Sepidermidis (5 of 20; 25%) were the most common bacteriaresponsible.

Survival and RejectionSix-month and 5-year survival of patients with sternalwound infection averaged 85% 8% and 74% 10%,compared with 92% 2% and 82% 3% in patientswithout wound infection (p 0.15) (Fig 1). Eleven pa-tients with deep sternal wound infection or acute medi-astinitis underwent aggressive surgical debridement,drainage, and reconstruction with 6-month and 5-yearsurvival rates averaging 91% 9% and 80% 10%,respectively (Fig 2). One patient with acute mediastinitisdied from uncontrolled sternal wound infection afterimplantation of a total artificial heart and transplantationand another patient died from massive hemorrhage sec-

720 CARRIER ET AL Ann Thorac SurgSTERNAL WOUND INFECTION 2001;72:719 24


3/5

ondary to erosion of the ascending aorta. Two patientsunderwent successful reconstruction of the ascendingaorta, with a Dacron (C. R. Bard, Haverhill, PA) graft in 1and a cryopreserved homograft in the other after theappearance of infected false aneurysms of the ascendingaorta (Fig 3). Omentoplasty and pectoralis muscle flapswere also used in these 2 patients to control the infectedmediastinal space (Fig 4). Three patients recovered suc-cessfully after surgical debridement, mediastinal drain-age, and sternal reclosure associated with the proper

antibiotic treatment.The freedom rate from acute rejection averaged 47%

4% 6 months after transplantation in patients who did notshow evidence of sternal wound infection, compared

with 43% 11% in patients with sternal wound infections(p 0.5). The number of treated acute rejection episodes

averaged 1.1 1.2 per patient in those who did not showevidence of sternal wound infection compared with 1.0 0.9 episode per patient in those with sternal woundinfections (p 0.8).

Multivariate Analysis

Recipient age (odds ratio 1.08, 95% confidence interval,1.05 to 1.1) was the only risk factor significantly correlatedwith the appearance of wound infection after heart trans-plantation. The use of mycophenolate mofetil, azathio-prine, and antithymocyte globulin was not associatedwith wound infection, nor was the presence of diabetesbefore transplantation.

Fig 1. Actuarial survival of patients with superficial, deep, andacute mediastinitis (infection) compared with patients without ster-nal wound infection. Survival was lower among patients with ster-

nal wound infection, but the difference is not statistically significant(p 0.15).

Fig 2. Actuarial survival of patients with deep sternal wound infec-tion and acute mediastinitis compared with patients without deepwound and mediastinal infection. Survival was similar in the twogroups.

Fig 3. Computed tomography scan showing (A) a false aneurysm ofthe ascending aorta (arrow) and (B) a mediastinal abscess behindthe ascending aorta (arrow). The patient was treated for a deep ster-nal wound infection immediately after heart transplantation butshowed evidence of mediastinal infection 6 months later. Cultures ofthe abscess isolated a methicillin-resistant Staphylococcus aureusbacteria.

721Ann Thorac Surg CARRIER ET AL2001;72:719 24 STERNAL WOUND INFECTION


4/5

Comment

Heart transplantation is an established treatment forpatients in end-stage heart failure. Although rejectionand systemic infections episodes have been well charac-terized among transplant patients, sternal wound infec-tion is seldom reported and rarely discussed. Yet, sternalwound infection after standard cardiac operations andafter heart transplantation is the major source of morbid-ity and mortality. The present study showed that sternalwound infection after heart transplantation correlatesdirectly with patient age. There was no significant rela-

tionship between the incidence of sternal wound infec-tion and protocols of immunosuppressive drugs used inthe present experience, although the incidence wasslightly higher among patients with the quadruple drugtherapy. There was no sternal infection in patients withthe double drug therapy of cyclosporine and prednisone,but the later protocol was used in the earliest part of ourexperience with heart transplantation enrolling onlyyoung patients. Moreover, survival of patients with ster-nal wound infection remains similar to those withoutwound infection after transplantation suggesting that, inmost cases, aggressive surgical debridement and appro-priate reconstructive approaches were successful.

From 1992 to 2000, including 13,199 patients undergo-ing cardiac operation in our institution, the annual inci-dence of acute mediastinitis varied from 0.13% to 1.33%.Our experience with acute mediastinitis occurring intransplant patients showed a high rate of 3%. Althoughrecipient age was the only risk factor associated with

sternal wound infection in the present study, a largercohort of patients could show the effect of pretransplantgeneral nutritional status, mechanical support, and im-munosuppressive drugs.

Nine patients in the present study had superficialwound infections and were treated at the outpatientclinic without significant morbidity. Eleven patients haddeep sternal wound infections or acute mediastinitisrequiring prolonged hospital stay and multiple surgicalprocedures of mediastinal drainage, debridement, reop-eration, and in 2 cases reconstruction of the ascendingaorta (Dacron graft in 1 case and cryopreserved ho-mograft in another) associated with pectoralis muscleflaps and omentoplasty to control the mediastinal in-fected space. Other authors have also reported the use ofmuscle flaps and of omentoplasty in patients with medi-astinal infection after conventional operation [9] or hearttransplantation [10, 11].

Coselli and colleagues [12] described the use of cryo-preserved homografts in patients with thoracic aorticgraft infections, an approach that we used in combinationwith omentoplasty and pectoralis muscle flaps in patientswho showed evidence of infected pseudoaneurysms ofthe ascending aorta at the site of the aortic anastomosis[13]. Although Argenziano and colleagues [14] showedthat wound infection in patients with left ventricularassist support does not adversely affect survival, local

infection surrounding a total artificial heart carries adismal prognosis [15], as was the case with 1 of ourpatients.

There is no clear guideline as to the level of immuno-suppression that should be maintained in patients withsignificant sternal wound infection after transplantation.Our practice has been to rely on cyclosporine and pred-nisone while azathioprine or mycophenolate mofetilwere stopped until we were confident that the sternal ormediastinal infection was controlled. The use of cyclo-sporine and prednisone was effective in preventing therejection process during these episodes of sternal woundinfection.

Sternal wound infection and acute mediastinitis re-

main a serious complication after heart transplantation.Although there was no significant difference in the inci-dence of sternal wound infection among the four proto-cols of immunosuppressive agents used, older patientsand those with quadruple drug treatment had the high-est rate of wound complications. Although old age wasshown to increase the incidence of wound infection, theselection criteria remain based on risks and benefits ofthe transplantation procedure. Immediate and aggres-sive surgical debridement of all infected sternal tissue ismandatory with cultures and proper antibiotic treatment.Mediastinal drainage, debridement of all infected andnecrotic tissue, and closure is most often successful, but

Fig 4. A patient underwent resection of the false aneurysm, drainageof the retroaortic abscess, reconstruction of the ascending aorta witha cryopreserved homograft, omentoplasty to control mediastinal deadspace, and pectoralis muscle flap to secure the sternal closure. Thepatient had a successful outcome and remains free from recurrence 6

months after the operation.

722 CARRIER ET AL Ann Thorac SurgSTERNAL WOUND INFECTION 2001;72:719 24


5/5

omentoplasty and pectoralis muscle flaps may be neces-sary whenever sternal or mediastinal dead space needsto be controlled. Cryopreserved homograft appears to bea suitable conduit for aortic reconstruction in the pres-ence of acute mediastinitis and infected pseudoaneurysmof the aorta; prosthetic material should probably be

avoided. Aggressive surgical treatment of sternal woundcomplications results in good short- and long-term sur-vival after heart transplantation.

References

1. Loop FD, Lytle BW, Cosgrove DM, et al. Sternal woundcomplications after isolated coronary artery bypass grafting:early and late mortality, morbidity, and cost of care. AnnThorac Surg 1990;49:17986.

2. Mossad SB, Serkey JM, Longworth DL, Cosgrove DM, Gor-don SM. Coagulase-negative staphylococcal sternal woundinfections after open heart operations. Ann Thorac Surg1997;63:395401.

3. Harbath S, Samore MH, Lichtenberg D, Carmeli Y. Pro-longed antibiotic prophylaxis after cardiovascular surgeryand its effect on surgical site infections and antimicrobialresistance. Circulation 2000;101:291626.

4. Jakob HG, Borneff-Lipp M, Bach A, et al. The endogenouspathway is a major route for deep wound infection. EurJ Cardiothorac Surg 2000;17:15460.

5. Eisen JE, Hobbs RE, Davis SF, et al. Safety, tolerability, andefficacy of cyclosporine microemulsion in heart transplantrecipients. A randomized, multicenter, double-blind com-parison with the oil based formulation of cyclosporine

results at six months after transplantation. Transplantation1999;68:66371.

6. Kobashigawa J, Miller L, Renlund D, et al. A randomizedactive-controlled trial of mycophenolate mofetil in hearttransplant recipients. Transplantation 1998;66:50715.

7. Carrier M, White M, Perrault LP, et al. A 10-year experiencewith intravenous thymoglobuline in induction of immuno-suppression following heart transplantation. J Heart LungTransplant 1999;18:121823.

8. Mathieu P, Carrier M, White M, et al. Effect of mycopheno-late mofetil in heart transplantation. Can J Surg 2000;43:2026.

9. Jurkiewicz JG, Bostwick J, Wood R, et al. Management of theinfected median sternotomy wound with muscle flaps. TheEmory 20-year experience. Ann Surg 1997;225:76676.

10. Ascherman JA, Hugo NE, Sultan MR, Patsi MC, Smith CR,Rose EA. Single-stage treatment of sternal wound complica-tions in heart transplant recipients in whom pectoralis majormyocutaneous advancement flaps were used. J Thorac Car-diovasc Surg 1995;110:10306.

11. Sood R, Cavarocchi NC, Mitra A, McClurken JB, KolffJ. Muscle flap closure for infected wounds after heart trans-plantation. Transplant Proc 1990;22:23949.

12. Coselli JS, Koksoy C, LeMaire SA. Management of thoracic

aortic graft infections. Ann Thorac Surg 1999;677:19903.13. Katsumata T, Moorjani N, Vaccari G, Westaby S. Mediasti-

nal false aneurysm after thoracic aortic surgery. Ann ThoracSurg 2000;70:54752.

14. Argenziano M, Catanese KA, Moazami N, et al. The influ-ence of infection on survival and successful transplantationin patients with left ventricular assist devices. J Heart LungTransplant 1997;16:82231.

15. Griffith BP, Kormos RL, Hardesty RL, Armitage JM, Dummer JS. The artificial heart: infection-related morbidity and itseffect on transplantation. Ann Thorac Surg 1988;45:40914.

INVITED COMMENTARY

Sternal wound infections following cardiac surgery havebeen well defined. Subscribing to the CDC definition ofsurgical wound infection (SWI) a deep infection ischaracterized by a subfascial location or involving thebone or retrosternal space (mediastinitis). The incidenceis generally well below 1% for valve procedures andincreases to 1% to 2% for coronary artery bypass grafting.Risk factors are consistent across series and include olderage, diabetes, obesity, chronic obstructive pulmonarydisease, current smoking, use of bilateral internal tho-racic arteries and surgical techniques that traumatize thetissue or interfere with wound healing. Mortality issignificant at 10% to 20%.

Heart transplantation SWI rate should be similar tothat of a valve procedure. In fact, one could expect aneven lower incidence because many of the risk factors forSWI are contraindications to transplantation and thesternum is not acutely devascularized. So on initial read-ing, the 3.9% superficial SWI and 4.9% deep infectionrates reported by Carrier and colleagues appear quitehigh. However as they point out there is very littleinformation published to compare these rates with. Aquick (unconfirmed) review of our transplant database(excluding left ventricular assist device [LVAD] patients)found a 5% SWI rate and a separate database managedby the Infectious Disease Department found a 2% inci-

dence of superficial SWI and a 3.3% deep SWI rate. Notthat much different than Carriers incidence.

Could it be that different risk factors play a role in SWIafter heart transplantation? Malnutrition, cardiac ca-chexia, chronic low cardiac output state, anemia, pro-longed hospitalization on inotropic support through cen-tral lines, and infections or colonization with nosocomialflora followed immediately by intense immunosuppres-sion may put these patients at increased infection risk.Unfortunately, very few variables were investigated inthis series. Inexplicably, 80% of the SWI occurred in whatwould appear to be a low risk population of UnitedNetwork for Organ Sharing status II patients waiting on

average only 4 months for transplantation, and, unlikeSWI in nontransplant patients, mortality was not signif-icantly increased (although a trend was suggested). Thisundoubtedly reflects the small numbers affected.

Their management paradigm supports an aggressivediagnostic and therapeutic approach, which I support.Prevention is the best. All nonpermanent central venouslines are replaced at the time of transplant and in LVADpatients the pump pocket and mediastinum are debridedof all necrotic material and copiously irrigated beforeimplanting the heart. If a deep SWI occurs, especially inthe patient who has had multiple previous operationsand a fixed mediastinum, obliteration of the infected

723Ann Thorac Surg CARRIER ET AL2001;72:719 24 STERNAL WOUND INFECTION

2001 by The Society of Thoracic Surgeons 0003-4975/01/$20.00Published by Elsevier Science Inc PII S0003-4975(01)03043-0

sternal wound infection after heart

Documents