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ADULT CARDIAC SURGERY:
The Annals of Thoracic Surgery CME Program is located online at http://cme.ctsnetjournals.org.
To take the CME activity related to this article, you must have either an STS member or an
individual non-member subscription to the journal.
Driveline Infections in Left Ventricular Assist
Devices: Implications for Destination Therapy
Vikas Sharma, MD, Salil V. Deo, MS, MCh, John M. Stulak, MD,
Lucian A. Durham III, MD, PhD, Richard C. Daly, MD, Soon J. Park, MD,
Larry M. Baddour, MD, Kashish Mehra, MBBS, and Lyle D. Joyce, MD, PhD
Divisions of Cardiovascular Surgery and Infectious Diseases, Mayo Clinic, Rochester, Minnesota
Background. Infection is one of the major limitations to
successful long-term support after ventricular assist device implantation. There are limited data specifically
examining the incidence and predictors of driveline
infections (DLI), with a changing treatment paradigm
toward destination therapy (DT) and longer duration of
support.
Methods. Between January 2007 and 2011, 143 patients
underwent HeartMate II (Thoratec, Pleasanton, CA) implantation, with 87 (61%) as DT. Driveline maintenance
strategy included sterile dressing changes with chlorhexidine and saline application, without prophylactic
oral antibiotics.
Results. DLI developed in 18 patients (12%) at a median of 182 days (range, 26 to 1,138 days) after implantation, among which 12 (66%) were from the DT cohort.
Infections were superficial in 15 (82%) and deep in 3
(18%). Trauma was documented in 6 patients (33%).
Seven patients (38%) needed readmission for DLI. Surgical debridement was needed in 3 (17%). All patients
were managed successfully, without the need for device
explantation or urgent cardiac transplantation. No patient required continuous antibiotic prophylaxis after the
infection subsided. Risk factor analysis identified duration of support as the only independent predictor of
infection (mean. 600 vs 390 days; p ⴝ 0.03). The odds of
having a DLI rose by 4% for every month of support.
Conclusions. Longer duration of support significantly
increased the risk of DLI and hence increased the risk of
DLI in patients with DT. DLI may be successfully
managed with antibiotics and local wound care. Most of
the infections were superficial, and progression to deep
pocket or pump infection is rare in our experience.
H
infections, including pump infection, pocket infection, or
driveline infections (DLI). The axial-flow devices, with
their smaller driveline and lesser intrathoracic dissection,
have contributed toward a reduction in the risks for DLI,
but DLI still remains a major cause of morbidity and
death, with important financial implications [5].
DLI is particularly important in patients with DT
therapy, because LVAD-specific infections seem to be
cumulative over time. There are limited data specifically examining the incidence and predictors of DLI in
axial-flow devices, with a changing treatment paradigm toward DT. We present our experience with the
management of DLIs with an axial-flow LVAD in a
single institution and its implication with increasing
use of LVAD as DT.
eart failure is a major public health epidemic, with
more than 500,000 new cases annually and a prevalence of more than 5 million patients [1]. The left
ventricular assist device (LVAD) represents one of the
major advances in the management of patients with
end-stage heart failure and has been shown to provide
longer survival and better quality of life in these patients
compared with optimal medical therapy [2]. The rates of
LVAD implants per year have increased fivefold from
2007 to 2011, with a twofold increase in implants for
destination therapy (DT) [3].
The Randomized Evaluation of Mechanical Assistance
for the Treatment of Congestive Heart Failure trial established the status of the LVAD as DT [4]. Infection remains
one of the major challenges and limits to successful
long-term support on LVAD, especially LVAD-specific
Accepted for publication May 24, 2012.
Address correspondence to Dr Sharma, Division of Cardiovascular Surgery, Mayo Clinic College of Medicine, 200 First St SW, Rochester,
MN 55905; e-mail: [email protected].
© 2012 by The Society of Thoracic Surgeons
Published by Elsevier Inc
(Ann Thorac Surg 2012;94:1381– 6)
© 2012 by The Society of Thoracic Surgeons
Material and Methods
After approval from the Institutional Review Board, we
conducted a retrospective record review of all consecutive patients who underwent continuous-flow LVAD im0003-4975/$36.00
http://dx.doi.org/10.1016/j.athoracsur.2012.05.074
ADULT CARDIAC
ORIGINAL ARTICLES: ADULT CARDIAC
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DRIVELINE INFECTIONS IN VADS
Ann Thorac Surg
2012;94:1381– 6
Fig 1. (A) A superficial driveline infection with disruption of the seal between the skin edges and the velour coating of the driveline. (B) A
cross-sectional computed tomography image of the upper abdomen depicts the presence of a multiloculated abscess cavity deep to the rectus
sheath near the insertion of the driveline.
plantation at Mayo Clinic from January 2007 to January
2011. All preoperative demographic factors were analyzed for the entire cohort. The primary end point was
DLI, and patients were accordingly separated into DLI
and no-DLI groups. The study excluded all other LVADrelated infections, such as LVAD pump infections, and
infections not related to the LVAD, such as catheterrelated bloodstream infection, pneumonia, and sternal
wound infection. Organisms cultured from the DLI site,
antibiotic susceptibility, and duration of antibiotic support were also studied.
Study Definitions
The International Society for Heart and Lung Transplantation (ISHLT) consensus statement [6] was used to
define the presence of DLI or pocket infection.
Prophylactic Antibiotic Protocol
Antibiotic preferences were surgeon-specific. One intravenous antibiotic or 2 antibiotics, along with an antifungal agent, were given within 30 minutes of skin incision.
Medications were readministered as determined by their
pharmacokinetic properties in the operating room. Chest
closure was initially temporary if hemorrhage was excessive after the procedure or hemodynamics were borderline. Mediastinal irrigation and change of dressings were
performed on alternate days until the sternum could be
approximated in the regular manner.
Antibiotics are given for 48 hours from the time of
operation or until the patient has invasive catheters,
whichever is later. Microbiologic testing is performed if a
DRIVELINE INFECTION. The presence of a DLI was defined by
clinical signs (ie, purulent drainage from the DLI site, an
abscess, or other evidence of infection involving the
driveline tract found on direct examination), histopathologic or radiologic examination, and isolation of organisms from culture fluid or tissue from the exit site (Fig 1).
POCKET INFECTION. A pocket infection was defined as an
infection that occurs in the space that holds the pump
device inside the patient’s body cavity. The pocket may be
intraabdominal or intrathoracic. Workup for suspected DLI
included a series of microbiologic and radiologic investigations involving multidisciplinary teams (Table 1).
Table 1. Investigations for Suspected Driveline Infection
●
●
●
●
●
●
●
White cell count, serial C-reactive protein, erythrocyte
sedimentation rate
Blood cultures if clinically indicated
Sterile aspirate for Gram-stain, KOH, routine bacterial and
fungal culture of driveline exit site, if pus present
Tissue samples from suspicious tissue surrounding driveline
sent for histologic analysis, Gram-stain, KOH, bacterial, and
fungal cultures
Chest roentgenogram
Echocardiogram
If suspicion of pocket infection or deep abscess—abdominal
ultrasound, CT abdomen ⫾ thorax ⫾ nuclear imaging
CT ⫽ computed tomography.
Fig 2. Diagram shows the dressing for the driveline exit site.
SHARMA ET AL
DRIVELINE INFECTIONS IN VADS
1383
Table 2. Distribution of Preoperative Risk Factors Between Groups With and Without Driveline Infection
Variablea
Age, years
Male sex
Destination therapy
Pre-op risk factors
COPD
Immunosuppression
Diabetes
Chronic renal failure
Body mass index, kg/m2
NYHA class IV
Pre-op IABP
Pre-op inotropes
Laboratory variables
Hemoglobin, g/dL
Serum creatinine, mg/dL
Serum BUN, mg/dL
Serum bilirubin, mg/dL
INR
Platelet count ⫻ 103/␮L
WBC count ⫻ 109/L
Albumin, g/dl
a
All patients (n ⫽ 143)
DLI (n ⫽ 18)
No DLI (n ⫽ 125)
61.3 ⫾ 12.2
123 (86)
87 (61)
60.0 ⫾ 16.9
16 (89)
11 (62)
61.5 ⫾ 11.5
107 (86)
76 (61)
0.64
0.69
0.97
36 (25.2)
7 (4.8)
48 (33.6)
80 (56)
30.8 ⫾ 10.2
98 (69.5)
59 (41.84)
81 (63.1)
7 (39)
2 (11)
7 (39)
12 (67)
31.6 ⫾ 8.6
6 (30)
4 (23.5
8 (47)
29 (23)
5 (4)
41 (33)
68 (54)
30.6 ⫾ 10.5
92 (74.2)
55 (44.4
81 (65.3)
0.16
0.25
0.61
0.32
0.65
⬍0.01
0.12
0.18
11.7 ⫾ 1.75
1.62 ⫾ 0.71
34.4 ⫾ 19.4
1.33 ⫾ 0.82
1.5 ⫾ 0.76
169.5 ⫾ 66.7
7.69 ⫾ 2.84
3.75 ⫾ 0.54
11.7 ⫾ 1.76
1.86 ⫾ 1.04
29.8 ⫾ 14
1.31 ⫾ 0.9
1.49 ⫾ 0.53
177 ⫾ 67.9
7.2 ⫾ 2
3.79 ⫾ 0.52
11.9 ⫾ 1.65
1.59 ⫾ 0.65
34.9 ⫾ 20
1.33 ⫾ 0.81
1.56 ⫾ 0.79
168 ⫾ 66.7
7.7 ⫾ 2.9
3.75 ⫾ 0.55
OR (95% CI)
0.18 (0.06–0.55)
p Value
0.54
0.29
0.20
0.93
0.61
0.63
0.40
0.77
Continuous data are shown as the mean ⫾ standard deviation; and categoric data as number (%).
BUN ⫽ blood urea nitrogen;
CI ⫽ confidence interval;
balloon pump;
INR ⫽ international normalized ratio;
COPD ⫽ chronic obstructive airway disease;
DLI ⫽ driveline infection;
IABP ⫽ intraaortic
NYHA ⫽ New York Heart Association;
OR ⫽ odds ratio;
WBC ⫽ white blood cell.
fever develops or white cell count rises, and antibiotics
are continued. We have a committed infectious diseases
team that guides appropriate antibiotic therapy, and a
regular audit is performed to update the antibiotic therapy guidelines according to the sensitivity spectrum of
commonly isolated organisms.
Driveline Care
Care of the driveline (Fig 2) involves coordinated efforts
between the nursing staff and the patient. Care of the
driveline exit site is performed daily, initially by the
nurse during the early postoperative period and is taught
to the primary caregiver before the patient leaves the
hospital. The caregiver wears a facemask and sterile
gloves, and chlorhexidine and saline swabs are used to
clean the 3-inch circular area around the exit site and the
driveline. The driveline is covered with two 4- ⫻ 4-inch
sterile gauze sheets with slits cut in them for passing
around the driveline. The patient wears an abdominal
binder at all times to prevent inadvertent pull on the
driveline. An equally important part of teaching is also
focused on detecting early signs of infection and skin
damage around the driveline.
Statistical Analysis
Categoric variables are presented as percentages, and
continuous data are presented as mean ⫾ standard
deviation. Relationships of categoric variables were analyzed using the two-tailed Fisher exact t test. Continuous
variables were analyzed using the ␹2 test or the Wilcoxon
test, as appropriate. Statistical significance is considered
for a p value of less than 0.05.
Results
Between January 2007 and November 2011, 143 patients
(86% men), who were a mean age of 61.32 ⫾ 12.26 years,
underwent HeartMate II implantation (Thoratec Corp,
Pleasanton, CA). VAD was implanted as DT in 87 (61%)
and as bridge to transplant (BTT) in the rest. The DT
cohort was significantly older than the BTT group (66.8 ⫾
7.5 vs 52.8 ⫾ 13.3 years; p ⬍ 0.01). Table 2 demonstrates
the distribution of pertinent preoperative variables in the
groups with and without DLI. Both groups had a similar
median duration of preoperative in-hospital stay
(p ⫽ 0.94).
DLI developed in 18 patients (12%) at a median of 182
days (range, 26 to 1,138 days) after implantation; of these,
11 (60%) were from the DT cohort. A DLI before 30
postoperative days developed in only 1 patient. Trauma
was documented in 6 patients (33%). Three (17%) patients had deep infections with documented abscess
formation in deep abdominal tissues. DLIs were
“proven” in 3 patients (17%), possible in 4 (22%), and
probable in 11 (61%). Only 1 patient (6%) had an associated pocket infection. Two patients (11%) presented with
positive blood cultures and clinical features suggestive of
sepsis. Seven patients (38%) needed readmission to the
hospital, whereas the rest were managed as outpatients.
The DLIs were distributed evenly throughout the study
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DRIVELINE INFECTIONS IN VADS
Ann Thorac Surg
2012;94:1381– 6
12%
150
120
90
8%
60
30
21%
10%
2008
2009
15%
14%
0
2007
2010
2011
Total
Fig 3. Bar graph shows the distribution of driveline infection by year.
period, showing that that there was no change in DLIs as
our experience with LVAD implants increased (Fig 3).
The microbiologic profile of the patients is summarized
in Table 3. Staphylococcus aureus and coagulase-negative
staphylococci were the most common organisms isolated.
Only 1 patient (6%) had polymicrobial infection. The
focus of treatment was on the use of appropriate antibiotics as determined by the results of microbiologic analysis of the isolated organism and secured immobilization
of driveline using the abdominal binder. Six patients
(33%) needed intravenous antibiotics, and the remaining
were successfully treated with oral antibiotics. Antibiotic
therapy was continued until the cessation of discharge
and erythema around the driveline or completion of
therapy, whichever was longer. Patients with positive
blood cultures underwent repeated sampling at regular
intervals until a negative result was obtained.
Excisional debridement and drainage was preformed
in 3 patients (17%), and the exit site was incised to
facilitate easy drainage of the purulent material. Two
patients needed more than one debridement session.
Only 1 patient (6%) progressed to a pump pocket infection, which needed aggressive debridement, drainage of
the pocket, intravenous antibiotics, and vacuum-assisted
wound closure.
Table 3. Profile of Patients With Driveline Infection
Variable
Patients with driveline infection
Commonest isolated organisms
Staphylococcus spp
Coagulase-negative
S aureus
Pseudomonas aeruginosa
Type of infection
Superficial
Deep
History of trauma
Surgical debridement
Fig 4. Bar diagram demonstrates the increment in the incidence of
driveline infection with increasing duration of left ventricular assist
device support.
All patients were successfully treated without the need
for VAD explantation or urgent transplantation. Four
patients (22%) had more than one episode of DLI, which
were separated by a median duration of 12 months. The
same organism was isolated in all patients during these
multiple episodes.
We did not find any significant difference in the groups
with and without DLI in postoperative morbidities, including reexploration for bleeding, delayed sternal closure, postoperative intensive care unit stay, or the need
for hemodialysis.
The entire cohort was supported on the LVAD for a mean
of 11.39 ⫾ 11 months. Patients with DLI had a significantly
prolonged duration of LVAD support (20.22 ⫾ 12.79 vs 13 ⫾
11.59 months; p ⫽ 0.03). Univariate nominal logistic regression analysis identified duration of support on the LVAD as
a significant predictor of DLI (p ⫽ 0.02). The odds that a DLI
would occur rose by 4% for every monthly increase in
support. At the end of 1 year, 62 patients from the original
cohort were on LVAD support, and the incidence of DLI
rose to 17.7% from a baseline of 11% for the entire group.
LVAD support for more than 18 months clearly predisposed the patients to a DLI, with 25% of the patients in this
group having had at least one episode during their support
period (odds ratio, 3.95; 95% confidence interval, 1.43 to
10.93; Fig 4).
Comment
No. (%)
18
7
4
3
2
15 (83)
3 (17)
6 (33)
3 (17)
Infection has always been an important cause of morbidity and death in patients supported on LVAD since the
first-generation pulsatile pumps. Sepsis was an important cause of death in the Randomized Evaluation of
Mechanical Assistance for the treatment of Congestive
Heart Failure trial, accounting for 41% of cases in the LVAD
patients [7]. The survival benefit of the LVAD group in this
trial did not extend beyond the first year of support,
underlining the role of infection as a contributor of poorer
late outcomes. There have been significant advances in the
new-generation continuous-flow pumps in size and design,
but they still depend on an extracorporeal driveline to
power and control the implanted device. DLIs hence con-
tinue to be an important source of adverse outcomes in
patients being supported on the LVAD as DT.
Our cohort of patients is older than the other reported
series, which is understandable because we have a higher
DT population compared with other series. Unlike some
authors, we have not found that preoperative variables,
such as immunosuppression, diabetes, and obesity [8 –10]
significantly influence the incidence of DLI. The patients in
both groups were in the hospital preoperatively for a
similar period, and even the use of an intraaortic balloon
pump or invasive catheters for inotropic support were
comparable in the DLI and no-DLI cohorts. The above
factors have been quoted in earlier studies as possible risk
factors for a DLI [10, 11]. This could be related to the
fastidious care of invasive catheters, adequate antibiotic
coverage, or unknown factors that cannot be elucidated. We
also found no significant relationship between DLI and the
duration of operation, blood product requirement, or postoperative stay, and this has also been demonstrated in
other articles [12, 13].
Trauma has always been an important inciting factor in
the development of DLI [14, 15]. Although a clear history
of this could be documented in only one-third of the
patients from our cohort, an unrecognized inadvertent
tug is all that is required to damage the seal between the
driveline and the skin. Further patient education and
compliance regarding proper driveline care and immobilization will play an important role in reducing the
incidence of these events in future.
As described in other articles [9, 10], we have predominantly cultured staphylococci (60% of all positive reports) from the driveline site swab. Previous studies have
also identified Staphylococcus or Pseudomonas spp as frequent causes of DLI because of their ability to form a
biofilm that is resistant to host defense mechanisms [16,
17]. Unlike patients in reports from other authors [18],
none of our patients had fungal infection, which is highly
resistant to conventional medical therapy. Most of our
infections were superficial (83%), with most being probable or possible DLI.
Along with appropriate antibiotic therapy, a few patients required surgical debridement. Surgical procedures, including prolonged antibiotic irrigation or relocation of the driveline exit site, have been used by some
with success [19, 20]. Vacuum-assisted therapy, used
traditionally for the care of nonhealing ulcers, is an
attractive option in the care of the debrided LVAD pocket
[21]. We successfully used this therapy to promote tissue
healing in a patient with a pocket infection.
Possible progression to a pocket infection is an important complication that may lead to the need for an LVAD
exchange or urgent cardiac transplantation [22, 23], but
we have been able to manage DLIs without the need to
resort to such extreme measures. We believe that LVAD
exchange and transplantation can certainly not be considered a standard approach to treat DLI.
Good patient education regarding the importance of
driveline immobilization, driveline care, and early recognition of signs of DLI, along with a regular and strict
follow-up is needed for early identification of infection.
SHARMA ET AL
DRIVELINE INFECTIONS IN VADS
1385
Once diagnosed, appropriate diagnostic measures to
determine the extent of infection and prompt initiation of
medical and surgical measures, if needed, are important
to limit the spread of infection. A multidisciplinary approach involving the surgeon, LVAD coordinators, nursing staff, and the infectious diseases committee is important in effective management of patients with DLI.
Although our institution has a surgeon-specific preoperative antibiotic protocol, the numbers of DLI patients
were too few to do an intragroup comparison for antibiotic efficacy. Because only 1 patient had early infection,
we believe that the contribution of variable prophylactic
antibiotic regimens to the development of DLI is minimal. The role of long-term prophylactic antibiotics after
the first episode of DLI is controversial because it may
lead to the emergence of multidrug-resistant species of
organisms. In our study, 4 patients (22%) had more than
one readmission for a DLI, and the same microbiologic
flora was isolated each time. In retrospect, it may be a
useful strategy to consider after the first DLI event.
We have conclusively proven that the most important
factor leading to a DLI is duration of support on the
LVAD. Although we found an incremental risk of 4% per
month of support, Zierer and colleagues [14] calculated a
cumulative hazard of 94% at the end of 1 year of LVAD
support. A case-control study demonstrated that the
mean duration of VAD support patients with a DLI was
more than twice the noninfected group [8]. This inference
is even more important as we enter the era of DT, with
the hope that VADs would one day be a comparable
alternative to heart transplantation.
In conclusion, DLIs are an important cause of morbidity in patients undergoing support with a LVAD. These
infections can be treated with a combination of appropriate medical and surgical therapy, without the need for
urgent heart transplantation or a pump exchange. The
odds that a DLI infection will develop are directly proportional to the duration of LVAD support. Patient education regarding driveline care and immobilization, strict
follow-up, and early recognition are imperative for effective therapy.
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INVITED COMMENTARY
Sharma and colleagues [1] have provided useful updated
information with respect to the management of left
ventricular assist device (LVAD) destination therapy patients. The authors’ finding that the risk of incurring a
drive-line infection (DLI) increases proportionally to the
duration of LVAD support, with the majority in the
destination therapy cohort, is intuitive. Of more import
are the authors’ conclusions that, with careful drive line
management, strict follow-up, and early recognition of
exit-site infections, this complication can be successfully
treated with relatively conservative measures in the vast
majority of cases, and that urgent transplantation or
pump exchange is rarely required.
Given that the drive line exit site in LVAD patients is,
in effect, chronically colonized with skin flora and likely
other pathogens, it is somewhat surprising and encouraging that the authors encountered a relatively low rate
of DLI (12%) over the 4-year study period. It is also
surprising that the authors were able to successfully treat
most of their infections with limited courses of oral antibiotics. I suspect that these DLIs were not, in fact, completely
eradicated but converted from acute to chronically infected
states, whereby an ascending infection into the pump
pocket did not occur as long as there was a route of distal
egress through what was essentially a chronically draining sinus.
In future studies, it would be useful to obtain data that
would facilitate developing validated, consensus antibiotic
© 2012 by The Society of Thoracic Surgeons
Published by Elsevier Inc
treatment and prophylactic regimens for DLIs, given that
current practices are empiric and variegated. It seems that
prolonged and repeated antibiotic courses administered
over the steadily increasing life spans of destination therapy patients will hasten the development of antibioticresistant organisms. Furthermore, it would be interesting
to determine whether the substantially smaller caliber
drive lines of newer devices (eg, HeartWare) will lead to
comparatively lower DLI rates than those encountered
with the HeartMate II devices observed in this study.
Fortunately, wireless control and power transmission
systems appear to be on the horizon and will likely lead
to significantly reduced LVAD infections.
David D. Yuh, MD
Section of Cardiac Surgery
Yale University School of Medicine
Yale-New Haven Hospital Heart and Vascular Center
330 Cedar St, Boardman 204
New Haven, CT 06510
e-mail: [email protected]
Reference
1. Sharma V, Deo SV, Stulak JM, et al. Driveline infections in left
ventricular assist devices: implications for destination therapy. Ann Thorac Surg 2012;94:1381– 6.
0003-4975/$36.00
http://dx.doi.org/10.1016/j.athoracsur.2012.06.004