Clinical outcome and hemodynamic behavior of the Labcor Dokimos Plus aortic valve
Christ et al. Journal of Cardiothoracic Surgery
Clinical outcome and hemodynamic behavior of the Labcor Dokimos Plus aortic valve
Torsten Christ 0
Konstantin Zhigalov 0
0 Equal contributors Department of Cardiovascular Surgery , Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin , Germany
Background: The Labcor Dokimos Plus (LDP) is a stented externally mounted pericardial aortic bioprosthesis, which was recently introduced in Europe. Aims of the study are evaluation of operative and postoperative results as well as hemodynamic performance. Methods: One hundred consecutive patients with a mean age of 65.9 ± 10.7 years (range 35-87) and a mean EuroSCORE II of 3.1 ± 3.9 (range 0.67-24.5) underwent aortic valve replacement with the LDP. Mean valve-size was 25.2 ± 1.7 mm. Concomitant procedures were performed in 34% of the cases. Postoperative clinical data were analyzed and hemodynamic performance of the prostheses was evaluated by transthoracic echocardiography. Clinical follow-up was 100%, echocardiographic follow-up was 93% complete. Results: Intraoperatively no peculiarities occurred. Mean cross clamp times for isolated and complex procedures were 74.5 ± 20.0 min and 103.7 ± 37.1 min, respectively. Patients were extubated after a mean of 9.4 ± 15.8 h. There were no perioperative strokes. Bleeding events occurred in 4 patients. 30-day-mortality was 2%. One case of early endocarditis occurred. Echocardiography showed maximum and mean pressure gradients of 18.1 ± 6.4 and 9.6 ± 3. 7 mmHg, respectively. Correspondingly to valve sizes 21, 23, 25 and 27 mm, mean pressure gradients were 17.3, 9.5, 8.5 and 10.2 mmHg, effective orifice areas were 1.92, 1.79, 2.0, 2.16 cm2 and indexed effective orifice areas were 1. 08, 0.95, 0.99 and 1.01 cm2/m2, respectively. No relevant regurgitations occurred. Conclusions: The LDP showed operatively no peculiarities and a satisfactory clinical outcome with low perioperative morbidity and mortality. The hemodynamic performance of the implanted valve sizes was satisfactory.
Stented aortic valve replacement; Biological prosthesis; Valve replacement; Echocardiography
Recently, a new bovine pericardial stented bioprosthesis
for the aortic position, the Labcor Dokimos plus (LDP),
became available in Europe. The design features are a low
profile stent with externally mounted leaflets . Yet, no
contemporary data about clinical outcome and
hemodynamic performance are available. We report about
our perioperative experience with this substitute, the early
clinical outcome and hemodynamic performance.
From October 2013 to February 2015 100 consecutive
patients underwent aortic valve replacement with LDP
prostheses, while a total of 358 patients received an
aortic valve replacement at our institution. The decision
to implant the bioprosthesis was made according to the
actual guidelines [2, 3]. Baseline preoperative
characteristics are displayed in Table 1.
The LDP prosthesis, manufactured in Labcor
Laboratories, Belo Horizonte, Brazil is a CE-marked stented
bovine pericardial bioprosthesis and available in sizes from
19 to 27 mm (Fig. 1). Special features of this prosthesis
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Table 1 Baseline characteristics and risk stratification
Age in years ± standard deviation
Body surface area ± standard
Active endocarditis (n)
Predominant cardiac rhythm
Atrial fibrillation (n)
Coronary artery disease (n)
Arterial hypertension (n)
Pulmonary hypertension (n)
Renal dysfunction (n)
Diabetes mellitus (n)
NYHA class (Mean ± standard deviation)
Isolated aortic valve replacement
Fig. 1 Lateral view and front view of the Labcor Dokimos Plus
are a low profile, an acetal copolymer stent covered with
polyester, externally mounted pre-molded leaflets fixed
with glutaraldehyde at zero pressure as well as a so
called Reducer® anti-calcification treatment.
A right upper hemisternotomy in the 4th intercostal
space was performed for isolated aortic valve
replacement and full sternotomy for combined procedures.
Standard cannulation of the ascending aorta and the
right atrium was performed in all cases except in two
patients with additional tricuspid valve repair. In these
cases bicaval cannulation was performed. Usually
normothermic perfusion was used. However, in complex
cases with impaired ventricular function mild
hypothermia (32–34 °C) was applied. After clamping of
the aorta, intermittent antegrade blood cardioplegia
according to Calafiore was performed. The ascending aorta
was transversely opened 1–2 cm above the commissures
for half of its circumference. After resection of the
diseased valve and thorough annular decalcification, sizing
with ball-sizers and LDP-sizers was performed. The
appropriate prosthesis was implanted with 12–20
horizontal felt-armed mattress sutures. The prosthesis was
positioned either supra-annularly or intra-annularly
depending on the distance between the aortic annulus and
the coronary ostia, the position of the coronary ostia,
calcifications in the coronary sinus and the size of the
annulus and the sinus coronarius. The intra-annular
position was chosen in patients with tubular sinuses,
possible coronary obstruction by the bioprosthesis and
in patients with aortic annuli above 29 mm. In smaller
annuli (≤21 mm), stentless valves were implanted
(according to institutional guidelines), what represents a
selection bias for this study. Mitral valve procedures
(with or without left atrial ablation), distal coronary
anastomoses and aortic annular enlargement were
performed before implantation of the LDP. Tricuspid
procedures were performed on the beating heart after the
aortic valve replacement. Aortic annular enlargement
was done using the Manouguian technique using a patch
of bovine pericardium to reconstruct the extended
aortotomy into the non-coronary cusp and the subaortic
curtain. The function of the prosthesis was controlled by
After approval by the local Ethics Committee pre-,
intraand early postoperative (until discharge) data were
prospectively collected. Hemodynamic performance was
evaluated using transthoracic echocardiography at
discharge. It was performed with a GE Vivid 7 Dimension
(General Electric, Fairfield, Connecticut, USA) to check
morphology and function of the implanted prostheses.
Two-dimensional and Doppler transthoracic
echocardiography was performed. Mean values for each
measurement were derived from three beats in sinus rhythm,
and five beats in those in non-sinus rhythm. Transaortic
flow velocities were assessed by continuous–wave
Doppler, while flow velocities in the left ventricular outflow
tract were assessed by pulsed–wave Doppler. Pressure
gradients were calculated using the Bernoulli equation.
The effective aortic valve orifice area (EOA) was
calculated with the continuity equation and indexed by the
body surface area of the patient (EOAI).
All data were prospectively collected and analyzed with
SPSS Statistics version 22.0.0 (SPSS Inc., Chicago,
Illinois). Descriptive statistics are reported as the mean
± standard deviation for continuous variables and as
absolute frequencies and percentages for categorical
Operative details are presented in Table 2. Smaller valve
sizes (≤21 mm) were implanted rarely, due to
institutional guidelines to implant stentless valves in these
cases. Intra-annularly implantation of the LDP was
performed due to a wide aortic annulus (>29 mm, n = 23),
possible coronary obstruction (n = 18) and calcification
or anatomical anomalies of the Valsalva sinuses (n = 16).
Supra-annularly implantation was performed in the rest
of the patients. No intraoperative complications
occurred and intraoperative mortality was 0%. Patients
were extubated after a mean of 9.4 ± 15.8 h. Three
patients developed a low cardiac output syndrome
postoperatively and therefore received extracorporeal life
support (ECLS) within the first 24 h after the operation.
These patients had undergone complex combined
procedures and suffered preoperatively from an impaired left
ventricular function with a left ventricular ejection
fraction ≤ 35%. ECLS could be weaned in two patients at the
4th and 5th day postoperatively, respectively. However,
both patients died due to intractable ventricular
fibrillation and septic multi-organ failure at the 9th and 44th
postoperative day, respectively. The third patient died at
the 6th postoperative day due to multi-organ failure. No
other fatalities occurred. Hence, in patients with
complex procedures the 30-day mortality was 5.9% and the
hospital mortality 8.8%. For patients undergoing isolated
valve replacement the 30-day mortality was 0%.
Postoperative complications included re-exploration
for bleeding, which had to be performed in four patients.
Furthermore, eight patients developed acute renal
insufficiency and required temporary dialysis. Insertion of a
permanent pacemaker became necessary in six patients.
There were no strokes or deep sternal wound infections.
Table 2 Operative characteristics
Combined procedures (n)
Coronary artery bypass grafting (n)
Mitral Valve Replacement (n)
Mitral Valve Repair (n)
Left atrial ablation (n)
Ascending Aorta Replacement (n)
Tricuspid Valve Reconstruction (n)
Aortic Annular Enlargement (n)
Implanted valve sizes
Technique of implantation
Duration of procedure (min)
Isolated procedures (min)
Combined procedures (min)
Cardiopulmonary bypass time (min)
Isolated procedures (min)
Combined procedures (min)
Aortic cross clamp time (min)
Isolated procedures (min)
Combined procedures (min)
One case of early postoperative endocarditis occurred,
which led to a successful secondary valve replacement at
the 30th postoperative day. Patients were discharged
after a mean of 10.5 ± 6.9 days.
Echocardiography was analyzed for 93% of the cases.
Excluded were data of 7 patients, due to insufficient
conditions early postoperatively (n = 4), death (n = 2;
patients with ECLS, who died on the 6th and 9th day
postoperatively) and endocarditis (n = 1). Maximum and
mean prosthetic pressure gradients at discharge were
18.1 ± 6.4 and 9.6 ± 3.7 mmHg, respectively. Mean EOA
and mean EOAI were 2.01 ± 0.52 cm2 and 0.99 ±
0.25 cm2/m2, respectively. Two cases of severe
patientprosthesis mismatch (EOAI < 0.65 cm2/m2) were
observed (mean body mass index in these patients was
33.3). Twenty-one cases of moderate
prosthesismismatch (EOAI > 0.65 cm2/m2 and < 0.85 cm2/m2)
were observed. No relevant central or para-valvular
regurgitation was evident. No structural or nonstructural
valve dysfunctions and no valve thrombosis could be
observed. Table 3 provides the detailed hemodynamic
data according to the different valve sizes.
Conventional aortic valve replacement is still a gold
standard for patients with relevant aortic valve disease
without excessive risk profile. Biological substitutes are
recommended for patients older than 65 years or those
with contraindications to systemic anticoagulation [2, 3].
Stented biological substitutes are easy to implant and
show acceptable hemodynamic performances. However,
there is still the necessity to improve these valves
concerning hemodynamic properties and clinical
performance as well as durability. The LDP was launched in
Europe in 2013. It´s innovative design combined with a
novel anti-calcification treatment makes it a promising
substitute in the category of stented bioprostheses. To
our knowledge, this is the first study that reports early
postoperative outcome and hemodynamic data in a
Procedural data, including cross clamp times, were
comparable to other stented bio-prosthetic heart valves
and verify the simplicity and safety of the
LDPimplantation [4–6]. However, one has to consider the
low mean age and predicted risk of the study cohort,
which was triggered by the increasing use of
transfemoral aortic valve replacement in our institution in
older high risk patients. Noticeably, intra-annularly
implantation occurred very frequently. This is triggered by
the institutional guideline to implant stentless valves in
smaller annuli, which leaves the stented valves for larger
annuli, where in turn intra-annularly implantation can
be advantageous. This proceeding also led to a
predominant male study population, by eliminating female
patients with small annuli. Consequently, 64% of valve size
27 mm was implanted intra-annularly.
The early clinical results after implantation of the LDP
were within normal limits for bioprostheses. The
postoperative course of most patients was uneventful.
However, the need of permanent pacemakers in six patients
was slightly higher than reported for the SJM Trifecta
. Moreover, there were eight patients requiring
temporary dialysis postoperatively. However, those patients
Table 3 Echocardiographic results according to labeled valve sizes
Gradient in mmHg
Maximum Pressure gradient in mmHg
Indexed Effective Orifice Area in cm2/m2
were multi-morbid and all but one had undergone
complex procedures. The 30-day mortality of 2.0% was lower
than the EuroSCORE II predicted mortality (3.1 ± 3.9%),
which is actually one of the best predictors for hospital
mortality after aortic valve replacement .
At first glance, hemodynamic data of the LDP in this
study were conclusive. Mean results, regarding pressure
gradients, EOA and EOAI were comparable or even
better than other bioprostheses, like the St. Jude Medical
Trifecta, the Sorin Mitroflow, the Medtronic Mosaic or
the Sorin Freedom Solo [6, 9–11]. While analyzing these
data it´s to consider, that the body surface area of our
study population was relatively high (but normal and
typical for German inhabitants), which lowered the
EOAI results. Additionally, only two cases of severe
patient-prosthesis-mismatch were evident. These cases
occurred in obese patients with valve size 25 mm, where
obesity biased (lowered) the EOAI by causing a higher
body surface area. Notably, also 8 of the 21 patients with
moderate-patient-prosthesis mismatch were obese (body
mass index above 30). But at second glance,
hemodynamic outcome with regard to the labelled valve
sizes showed conflicting results in comparison to various
other available bioprostheses. For this evaluation, data of
the 21 mm LDP was not considered, due to the low
number of cases. Data for valve-sizes 23 mm and 25 mm
were comparable to data published for the SJM Trifecta
regarding pressure gradients, EOA and EOAI [7, 12]. In
contrast, data for size 27 mm showed inferior results
than the SJM Trifecta. The comparison to the Sorin
Mitroflow, a stented pericardial bioprostheses, showed
comparable pressure gradients for valve-sizes 23 mm
and 25 mm, whereas LDP size 27 mm showed higher
gradients . The EOAI of the Sorin Mitroflow was
lower for all valve sizes, but the gap to the LDP was
closest for the 27 mm prosthesis. The Medtronic
Mosaic, a stented porcine bioprostheses, showed higher
mean pressure gradients for valve sizes 23 mm and
25 mm and comparable values for size 27 mm .
Upon consideration of the EOA of the Medtronic
Mosaic, values were comparable for valve sizes 23 mm
and 25 mm, and higher for size 27 mm . The first
generation porcine stentless valves (Medtronic Freestyle,
SJM Toronto) showed a clear disadvantage in terms of
pressure gradients and EOA [13, 14]. On the contrary,
the latest generation of pericardial stentless valves
showed lower transvalvular gradients compared to our
data . Even so, the EOAI of these valves was only
slightly above results of the LDP, but once again with
the widest gap for valve size 27 mm . According to
the comparison with these studies, valve sizes 23 mm
and 25 mm showed excellent hemodynamic properties,
while a slightly impaired function of valve size 27 mm
was evident. Possibly, the high percentage of
intraannularly implanted valves in this size has an impact,
due to the change of the hemodynamic flow pattern
caused by the stent in the aortic annulus. However, our
results showed no difference between the intra-annular
and the supra-annular position for valve size 27, possibly
due to the low number of cases. Hence, further studies
with larger cohorts and a higher number of implants per
size are required. Additionally, longer follow-up is
necessary to confirm these findings in mid-term and
The Labcor Dokimos Plus was easy to implant, offered
operatively no peculiarities and patients showed a satisfactory
clinical outcome. Hemodynamic results were pleasing.
ECLS: Extracorporeal life support; EOA: Effective aortic valve orifice area;
EOAI: Indexed effective aortic valve orifice area; LDP: Labcor Dokimos Plus
Availability of data and material
The datasets generated during and/or analyzed during the current study are
not publicly available due to reasons of data protection but are available
from the corresponding author on reasonable request.
TC analyzed and interpreted the patient data and wrote the manuscript. KZ
performed data acquisition and was a major contributor in writing the
manuscript. WK and SH were major contributors in writing the manuscript.
All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
The Study was approved by the Ethics committee of the
CharitéUniversitätsmedizin Berlin (Reference number EA1/053/15). Patients
consented into participation in the study.
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