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Orıgı na l Ar tıcle / Özgün Ma k ale
Turkis h Journal of Thoracic and Cardiovascular Surgery 2024;32(2):141-150
Mustafa Mert Ozgur, Mehmet Aksut, Tanıl Ozer, Barış Gurel, İsmail Yerli,
Mine Şimşek, Sabit Sarikaya, Kaan Kırali
Comparison of minimal invasive extracorporeal circulation versus standard
cardiopulmonary bypass systems on coronary artery bypass surgery
Koroner arter baypas cerrahisinde minimal invaziv ekstrakorporeal dolaşım ile
standart kardiyopulmoner baypas sistemlerinin karşılaştırılması
Department of Cardiovascular Surgery, Koşuyolu High Specialization Training and Research Hospital, İstanbul, Türkiye
Received: September 14, 2023
Accepted: March 19, 2023
Published online: April 30, 2024
Corresponding author: Mus tafa Mer t Ozgur.
E-mail: drmertozgur@gmail.com
This is an ope n access ar ticle und er the terms of t he Creati ve Commons At tribut ion-No nCommerc ial License , which
permits us e, distribu tion and rep roduction i n any medium , provided th e original wo rk is properl y cited and is n ot used for
commercial purposes (http://creativecommons.org/licenses/by-nc/4.0/).
Cite this ar ticle as: Oz gur MM, Aksut M, Ozer T, Gure l B, Yer li İ, Sarikaya S, et al. Com parison of mi nimal i nvasive
extracorporeal circulation versus standard cardiopulmonary bypass systems on coronary artery bypass surgery.
Turk Gog us Kalp D ama 20 24;32(2):141-150. doi: 10.5 606/tgkdc.derg isi.2024 .255 84.
Doi: 10. 560 6/tgkdc.d ergisi.2 024. 2558 4
ÖZ
Amaç: Bu çalışmada koroner arter baypas grefti hastalarına
yönelik minimal invaziv ekstrakorporeal dolaşım sistemi ile
ilgili deneyimlerimizi paylaştık.
Ç a l ı ş m a p l a n ı : Temmuz 2021 - Nisan 2023 tarihleri
arasında minimal invaziv ekstrakorporeal dolaşım ile
koroner arter baypas grefti uygulanan 83 hasta (63 erkek,
20 kadın; ort. yaş: 61.9±8.9 yıl; dağılım, 35-81 yıl) ve
konvansiyel kardiyopulmoner baypas ile koroner arter
baypas grefti uygulanan 80 hasta (65 erkek, 15 kadın;
ort. yaş: 60.5±8.8 yıl; dağılım, 43-82 yıl) olmak üzere
toplam 163 hasta retrospektif çalışmaya dahil edildi. Aynı
ekip tarafından gerçekleştirilen elektif koroner baypas
vakaları çalışmaya dah i l edild i. Ölüm, maj ör advers kardiya k
ve serebrovasküler olay, hastane yatışları ve transfüzyon
gereksinimleri değerlendirildi.
Bul gu lar: İki grup arasında cinsiyet dağılımı, yaş,
komorbidite ve kan değerleri açısından anlamlı fark yoktu.
Ameliyat sırasında, minimal invaziv ekstrakorporeal dolaşım
grubunda distal anastomoz sayısı biraz daha fazlaydı ve aortik
kros klemp ve kardiyopulmoner baypas için benzer süreler
vardı. Tamponad, kanama, atriyal fibrilasyon, sol ventrikül
ejeksiyon fraksiyonunda iyileşme veya azalma ve ameliyat
sonrası drenaj gibi ameliyat sonrası sonuçlar iki grup arasında
benzerdi. Bununla birlikte, minimal invaziv ekstrakorporeal
dolaşım grubuna daha az paketlenmiş eritrosit ve taze donmuş
plazma transfüzyonu yapıldı ve yoğun bakım ünitesinde kalış
süresi daha kısaydı.
S o n u ç : Minimal invaziv ekstrakorporeal dolaşım sistemi kanı
etkili bir şekilde korumaktadır, koroner arter baypas greftlemede
ek komplikasyon olmadan daha düşük aktif pıhtılaşma zamanı
değerleriyle çalışmaktadır ve anemisi olan veya yüksek doz
heparinizasyon için nispeten yüksek riskli hastalar için daha iyi
bir seçenek sunabilmektedir.
A n a h t a r s ö z c ü k l e r : Komplikasyonlar minimal invaziv ekstrakorporeal
dolaşım, koroner arter baypas greftleri, enflamatuar yanıt, patofizyoloji.
ABSTRACT
Background: In this study, we shared our experience with the
minimal invasive extracorporeal circulation system for coronary
artery bypass grafting patients.
Methods: A total of 163 patients were included in the
retrospective study, with 83 patients (63 males, 20 females;
mean age: 61.9±8.9 years; range, 35 to 81 years) undergoing
coronary artery bypass grafting with minimal invasive
extracorporeal circulation and 80 patients (65 males,
15 females; mean age: 60.5±8.8 years; range, 43 to 82 years)
undergoing coronary artery bypass grafting with conventional
cardiopulmonary bypass between July 2021 and April 2023.
Elective coronary bypass performed by same surgical team
were included in the study. Mortality, major adverse cardiac
and cerebrovascular event, hospital stays and transfusion
requirements were evaluated.
Results:There were no significant differences in sex distribution,
age, comorbidities, and blood values between the two groups.
Intraoperatively, the minimal invasive extracorporeal circulation
group had a slightly higher number of distal anastomoses and
comparable times for aortic cross-clamp and cardiopulmonary
bypass. Postoperative outcomes such as tamponade, bleeding,
atrial fibrillation, left ventricular ejection fraction improvement
or reduction, and postoperative drainage were similar between
the two groups. However, the minimal invasive extracorporeal
circulation group had fewer transfusions of packed red blood
cells and fresh frozen plasma and a shorter length of stay in the
intensive care unit.
Conclusion: The minimal invasive extracorporeal circulation
system effectively preserves blood, works with lower activated
clotting time values without additional complications in coronary
artery bypass grafting, and could present a better option for
patients with anemia or patients with a relatively high risk for
high-dose heparinization.
Keywords: Complications minimal invasive extracorporeal circulation,
coronary artery bypass grafts, inflammatory response, pathophysiology.
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Turk Gogus Kalp D ama
2024;32(2):141-150
Coronary artery bypass grafting (CABG), a
frequent and life-saving cardiac procedure, is generally
performed with a conventional cardiopulmonary
bypass (CPB) system since the first days of cardiac
surgery in the 1960s. Conventional CPB involves
exposing blood to air and nonendothelial surfaces,
leading to coagulation cascades, platelet activation, and
the occurrence of microemboli and thromboembolic
events.[1] To address these concerns, minimal invasive
extracorporeal circulation (MiECC) has been
established in the past decades.[2]
Current literature demonstrates that MiECC
surpasses conventional CPB in various aspects,
including reduced blood product usage, shorter
hospital and intensive care unit (ICU) stays,
decreased mortality and thromboembolic events,
and improved myocardial protection.[2] Based on
accumulating evidence, MiECC was recommended
as class 2A evidence for blood preservation in
the 2019 European Association for Cardio-Thoracic
Surgery (EACTS)/European Association of
Cardiothoracic Anaesthesiology (EACTA)/European
Board of Cardiovascular Perfusion (EBCP) guideline
on CPB in cardiac surgery and 2021 Society of
Thoracic Surgeons (STS)/Society of Cardiovascular
Anesthesiologists (SCA)/American Society of
ExtraCorporeal Technology (AmSECT)/Society for
the Advancement of Blood Management (SABM)
update to the clinical practice guidelines on patient
blood management.[3,4] Furthermore, Turkish national
societies recommend the use of MiECC for specific
indications as a measure to conserve blood and
prevent the need for transfusions.[5]
This study aimed to assess the potential effects and
benefits of MiECC on outcomes of isolated coronary
surgery. The primary objective of the study was to
evaluate the effectiveness of MiECC in protecting
blood and reducing the usage of blood products.
Additionally, the study aimed to assess the impact of
MiECC on secondary endpoints, such as the reduction
in length of stay in the ICU and the inpatient service.
PATIENTS AND METHODS
This single-center retrospective observational
study was carried out with 163 patients who
underwent isolated elective CABG with sternotomy
at the Koşuyolu High Specialization Training and
Research Hospital, Department of Cardiovascular
Surgery between July 2021 and April 2023.
Among these patients, 83 (63 males, 20 females;
mean age: 61.9±8.9 years; range, 35 to 81 years)
underwent CABG with the use of MiECC, while
80 patients (65 males, 15 females; mean age:
60.5±8.8 years; range, 43 to 82 years) underwent
CABG with conventional CPB. The same surgical
team, specializing in both MiECC surgery and
isolated coronary bypass, performed operations
on both groups of patients. The elective cases
were performed in the same operating theatre with
the same anesthesiologists and perfusionists. In
emergency cases, a perfusionist or anesthesiologist
who could operate the MiECC system may not have
been available. Additionally, a centrifugal pump
was not present in all operating rooms. Therefore,
in emergency cases, the operations could have been
performed at different operating rooms that did not
have a centrifugal pump to combine with the MiECC
system. Since emergency cases were not included
in the MiECC group, they were excluded from the
conventional system group to achieve a sufficient
comparison. Furthermore, since we did not have the
experience of using MiECC systems in minimally
invasive CABG and in cases where concomitant
cardiac intervention is required, this group of
patients was also excluded from the study.
Surgical technique
All surgeries were conducted through standard
median sternotomy under general anesthesia, utilizing
grafts from the left internal mammary artery and the
great saphenous vein. Both groups underwent standard
aortic and single two-stage venous cannulation.
Initially, intermittent cold blood cardioplegia with an
antegrade approach was employed. Later, we changed
our strategy and started using Del Nido cardioplegia in
both groups.
A MiECC system (LivaNova, London, UK) with
the Sorin Revolution Centrifugal pump, 3/8-inch
coated tubing, and a hollow fiber oxygenator featuring
an integrated arterial filter (Inspire 6F Phisio-coated;
LivaNova, London, UK) was utilized in the MiECC
group. The perfusion strategy evolved over time,
initially incorporating type 2 and 3 MiECC systems
with a soft-shell reservoir bag and venting system.
As we adapted to the system, the type 1 MiECC
system became the routine choice. Mild hypothermia
(33-34°C) was maintained, with a target flow rate
index of 2.5 L/min per square meter of body surface
area using nonpulsatile flow. The system was primed
with 800 to 1000 mL of Ringer solution along with
100 mL of mannitol. Retrograde autologous priming
(RAP) was performed in hemodynamically stable
cases. Heparin (100 IU/kg) was given intravenously
to initiate perfusion. According to the position paper
from the MiECTiS (Minimal Invasive Extracorporeal
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et al.
Compa rison of MiECC and CPB in CABG
Tech nologies Inter national Society), the ta rget activated
clotting time (ACT) value for the CABG cases is
around 300 to 350 sec.[6] Although the operations were
initially performed with higher ACT values, over time,
as our strategies were updated and the system became
almost completely closed circuit, the operations were
performed at lower ACT levels. The target ACT
value was maintained between 250 and 350 sec.
with close monitoring and repeated measurements
during perfusion. After each ACT measurement, it
was determined whether an additional dose of heparin
would be administered by the joint decision of the
surgeon, anesthesiologist, and perfusionist, considering
the course of the operation and the estimated perfusion
time. Initially, coronary suction was used in a few
cases involving type 2 or 3 MiECC. The use of
autotransfusion (cell saver) or coronary suction was
avoided in the early stages of type 1 MiECC cases, and
instead, we focused on strict bleeding control. However,
after encountering high transfusion requirements and
unnecessary blood loss in two to three cases, we
decided to change our approach and began routinely
using cell saver and type 1 MiECC systems. It is
important to note that the tubing systems were coated
with phosphorylcholine, and the priming fluid did not
contain heparin.
The extracorporeal circuit in the CPB group was
an open system, featuring 3/8 to 1/2-inch noncoated
tubing (Bıçakcılar, İstanbul, Türkiye), an S5 heart-
lung machine (LivaNova, London, UK), and a hollow
fiber oxygenator with an integrated arterial filter (FX
Terumo FX25; Terumo, Tokyo, Japan). Surgeries were
conducted under moderate hypothermia (30-32°C).
The system was primed with 1500 mL of Ringer
solution supplemented with 150 mL of mannitol.
Heparin (300-400 IU/kg) was given intravenously to
initiate CPB, with a target ACT value of >450 sec.
during the surgery. In the standard CPB group, only
cardiotomy suction was routinely used. Cell saver was
not used in this group.
Data collection
Preoperative data were meticulously gathered by
examining medical records from our department and
cross-referencing them with the national electronic
recording system. Intraoperative data were collected
by reviewing surgical records. This involved
documenting crucial information such as the number
of distal anastomoses, aortic cross-clamp time,
CPB time, initial hematocrit (Hct) levels, Hct levels
after the operation, postoperative Hct difference,
maximum ACT during the operation, and ACT after
the operation.
Postoperative data were gathered from multiple
sources, including ICU and general ward records, as
well as national electronic health system records, to
ensure a comprehensive approach. This allowed for
the recording of vital variables such as tamponade,
stroke, bleeding, atrial fibrillation, transfusion
requirements including fresh frozen plasma (FFP)
and packed red blood cells (PRBCs), postoperative
drainage, postoperative troponin levels, postoperative
hemoglobin (Hgb) levels, postoperative Hct levels,
left ventricular ejection fraction, intubation time, ICU
duration, and length of hospital stay.
Stage 1 acute kidney injury was defined as
serum creatinine of 1.5 to 1.9 times of baseline.
Stage 2 was defined as serum creatinine of
2.0 to 2.9 times of baseline. Stage 3 was defined as
serum creatinine ≥3.0 times of baseline or new-onset
dialysis.[7]
Anemia and postoperative transfusion strategy
The cut-off values for normal Hgb were 13.5 g/dL
for male and 12 g/dL for female patients. Symptomatic
(e.g., hypotension, tachycardia, and dyspnea) patients
with Hct values <25 were routinely transfused with
1 unit of PRBCs. In addition, all anemic patients were
started on oral iron therapy.
Statistical analysis
Statistical analysis was performed using the IBM
SPSS version 22.0 software (IBM Corp., Armonk, NY,
USA). The categorical data in this study were reported
as percentages, reflecting the proportion of individuals
within each category. Numerical data were presented
as mean ± standard deviation (SD). To evaluate any
differences, statistical analyses were performed using
chi-square tests and measures such as Phi and Cramer's
test for categorical variables. For numerical variables,
Student’s t-test was employed. A p-value <0.05 was
considered statistically significant.
RESULTS
Patient characteristics
The sex distribution was similar between the
MiECC and conventional CPB groups, with 24.1%
female patients in the MiECC group compared to
18.8% in the CPB group (p=0.406). The mean age
showed no significant difference between the groups
(p=0.796). Other variables such as hypertension
(p=0.916), type 2 diabetes mellitus (p=0.531), anemia
(p=0.111), and left ventricular ejection fraction
(p=0.142) were comparable between the two groups.
In terms of blood values, the mean preoperative Hgb
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Turk Gogus Kalp D ama
2024;32(2):141-150
levels were 13.5±2.1 g/dL in the MiECC group and
13.9±1.7 g/dL in the CPB group (p=0.051). Similarly,
preoperative Hct levels were slightly lower in the
MiECC group compared to the CPB group (p=0.059).
However, the preoperative C-reactive protein (CRP)
level was significantly higher in the MiECC group
(p =0.036, Table 1).
Intraoperative findings were compared between
the MiECC and conventional CPB groups, as shown
in Table 2. The mean distal anastomosis count was
3.3±0.9 in the MiECC group and 3.1±0.8 in the CPB
group, indicating a slightly higher number in the
MiECC group (p=0.064). The mean aortic cross-clamp
time was 56.0±21.1 min in the MiECC group and
60.0±20.4 min in the CPB group, with no significant
difference (p=0.381). Similarly, the CPB time was
comparable between the two groups, with a mean of
97.6±24.8 min in the MiECC group and 101.3±28.0 min
in the CPB group (p=0.651).
Regarding blood parameters, the initially
measured Hct levels were 37.6±6.4 in the MiECC
group and 39.4±5.5 in the CPB group, with no
significant difference (p=0.163). However, the
perioperative difference in Hct levels (perioperative
Table 1. Patient characteristics
MiECC Conventional CPB
Variables n % Mean±SD n % Mean±SD p
Age (year) 61.9±8.9 60.5±8.8 0.796
Sex
Female 20 24.1 15 18.8 0.406
Hypertension 14 16.9 13 16.2 0.916
Peripheral arterial disease 2 2.4 22.5 0.970
Type 2 diabetes mellitus 41 49.4 35 43.8 0. 531
Anemia 36 43.4 24 31.2 0.111
Left ventricular ejection fraction 56.0±9.9 55. 4±11.1 0.142
Blood values
Hemoglobin 13.5±2.1 13.9±1.7 0.051
Hematocrit 40.4±5.6 41.5±4.5 0.059
C-reactive protein 6. 5±7.7 5.4±5.7 0.036
MiECC: Minimal invasive extracorporeal circulation; CPB: Cardiopulmonary bypass; SD: Standard deviation.
Table 2. Operative characteristics
MiECC Conventional CPB
Mean±SD Mean±SD p
Variables
Distal anastomosis count 3.3±0.9 3.1±0.8 0.064
Aortic cross clamp time 56.0±21.1 60.0±20.4 0. 381
Cardiopulmonary bypass time 97.6 ± 24. 8 101.3±28.0 0.651
Blood values
Hematocrit at the beginning 37.6±6.4 39.4±5. 5 0.163
Hematocrit at the end of operation 33.6±6.2 31.7±5.7 0.472
Perioperative hematocrit difference 4.5±4.1 8. 0±5.2 0.016
Maximum activated clotting time 316±53 580±127 0.001
MiECC: Minimal invasive extracorporeal circulation; CPB: Cardiopulmonary bypass; SD: Standard deviation.
145
Ozgur M M,
et al.
Compa rison of MiECC and CPB in CABG
Hct difference) was significantly higher in the
CPB group (p=0.016). The course of the Hgb and
Hct values are shown in Figure 1 and Figure 2.
The maximum ACT during the procedure was
316±54 sec in the MiECC group and 580±127 sec
in the CPB group, showing a significant difference
(p =0.0 01).
Postoperative outcomes were compared between
the MiECC and conventional CPB groups, as shown in
Table 3. The occurrence of postoperative tamponade
was similar between the two groups, with 1.2% (n=1)
in both the MiECC and CPB groups (p=0.979).
While no cases of postoperative reexploration for
bleeding were reported in the MiECC group, 2.5%
(n=2) of patients in the CPB group experienced
reexploration for bleeding (p=0.244). Postoperative
atrial fibrillation occurred in 2.4% (n=2) of patients
in the MiECC group and 5.1% (n=4) in the CPB
group, with no significant difference (p=0.355).
Postoperative acute kidney injury was observed in
8.3% (n=7) of patients in the MiECC group and 14.5%
Table 3. Postoperative outcomes
MiECC Conventional CPB
n % Mean±SD n % Mean±SD p
Variables
Postoperative tamponade 1 1.2 11.2 0.979
Postoperative bleeding 00.0 22.5 0.244
Postoperative AKI 78.3 11 14.5 0.220
Postoperative atrial brillation 2 2.4 45.1 0.355
Postoperative stroke 0 0.0 00.0 -
Postoperative TIA 0 0.0 00.0 -
Postoperative drainage 513±2 88 630±297 0.254
Transfused PRBCs 1.0 ±1.3 1.6 ±1.9 0.004
Transfused FFP 0.1±0.3 0.4±0.8 0.001
Postoperative LVEF 56.2±9.4 57.0 ± 9.3 0.747
Intubation time (h) 7.9±3.7 7.6 ± 3.4 0.460
LOS ICU (Days) 1.2±0.5 1.5±1.1 0.0 01
LOS ward (Days) 6.1±1.7 6.6±2.2 0.221
Blood values
Postoperative hemoglobin D1 10.3±1.7 9.9 ±1.6 0.449
Postoperative hemoglobin D3 8.7±1.3 8.4±1.4 0.498
Postoperative hemoglobin D4 9.4 ±1.6 9.3±1.4 0.139
Postoperative hematocrit D1 30.7±4.8 29.7±4.6 0.432
Postoperative hematocrit D3 26.9±4.4 25.5± 4.0 0.288
Postoperative hematocrit D4 28.6±4.8 29.0±4. 2 0.437
Postoperative C-reactive protein D1 56 ±54 49±37 0.764
Postoperative C-reactive protein difference 50±48 49±36 0.643
Postoperative C-reactive protein D3 179±74 178±75 0.554
Postoperative Cr D1 1.08±0.51 0.99±0.31 0.118
Postoperative Cr D3 1.05± 0.75 0.98±0.45 0.271
Postoperative Tr D1 0.576±0.616 0.622±0.886 0.425
MiECC: Minimal invasive extracorporeal circulation; CPB: Conventional cardiopulmonary bypass; SD: Standard deviation; AKI: Acute kidney injury; TIA:
Transient ischemic attack; PRBCs: Packed red blood cells; D: Day; FFP: Fresh frozen plasma; LVEF: Left ventricular ejection fraction; LOS: Length of stay;
ICU: Intensive care unit; Tr: Troponin.
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Turk Gogus Kalp D ama
2024;32(2):141-150
(n=11) of patients in the CPB group without statistical
difference (p=0.220). There were no recorded cases
of postoperative transient ischemic attack or stroke in
either group.
The mean postoperative drainage was 513±288 mL
in the MiECC group and 630±297 mL in the CPB
group, showing no significant difference (p=0.254).
However, a significant difference was observed in the
transfusion of PRBCs and FFP. The MiECC group
received a mean of 1.0±1.3 units of PRBCs compared
to the 1.6±1.9 units in the CPB group (p=0.004). The
transfusion of FFP was 0.1±0.3 units in the MiECC
group and 0.4±0.8 units in the CPB group (p=0.001).
The mean intubation time was similar between the
MiECC and conventional CPB groups, with 7.9±3.7 h
and 7.6±3.4 h, respectively (p=0.460). However, the
length of stay in the ICU was significantly shorter
in the MiECC group, with a mean of 1.2±0.5 days
compared to 1.5±1.1 days in the conventional CPB
group (p=0.001). The length of stay in the inpatient
service did not show a statistically significant difference
between the MiECC and CPB groups, with values of
6.1±1.7 days and 6.6±2.2 days, respectively (p=0.221).
Rega rd in g b l oo d va lue s, no s ign ific an t d iffe r en ce s
were observed between the MiECC and CPB groups
in terms of postoperative Hgb levels (p=0.449).
Similarly, there were no significant differences
in postoperative Hct levels (p=0.432). The
postoperative levels of CRP were also comparable
between the MiECC and CPB groups, showing no
statistically significant differences. Additionally,
the postoperative troponin levels on the first day
did not differ significantly between the MiECC and
CPB groups, with values of 0.576±0.616 ng/mL and
0.622±0.886 ng/mL, respectively (p=0.425).
Although there was no statistically significant
difference between groups, postoperative AKI
incidence was lower in the MiECC group (8.5%)
than in the CPB group (14.5%; odds ratio 1.69).
DISCUSSION
This study, positioned among the most extensive
investigations in Europe employing the state-of-the-
art MiECC system, underscores the hematoprotective
significance of MiECC. It unveils the practicality
of performing CABG with reduced ACT values.
The MiECC technique was developed to enhance
biocompatibility and ensure more physiological
perfusion during cardiac surgeries, serving as an
alternative to conventional CPB. Theoretically, MiECC
offers several advantages. First, it prevents air-blood
contact, thereby reducing the risk of complications.
Additionally, it minimizes inflammation, leading
to reduced mechanical trauma compared to roller
pumps.[2] Furthermore, MiECC maintains optimal
perfusion efficiency by utilizing a lower prime volume,
thereby preventing hemodilution. Numerous clinical
Figure 1. Course of hemoglobin values during the pre- and
postoperative period.
PO: Preoperative; D: Day.
Mean hemoglobin (g/dL)
Preoperative PO D1 PO D3 PO D4
14.50
14.0 0
13.0 0
13.50
12.00
10.00
11.0 0
9.0 0
7.50
6.50
11.5 0
9.5 0
8.00
12.50
10.50
8.50
7.0 0
6.00
MiECC CPB
Preoperative Intraoperative
before the
incision
Mean hematocrit (%)
Intraoperative
after the
incision
closure
PO D1 PO D3 PO D4
43.0 0
35.0 0
27. 0 0
39.00
31.0 0
23.0 0
41.0 0
33.0 0
25.00
37. 0 0
29. 00
21.0 0
Figure 2. Course of hematocrit values during the pre- and postoperative period.
147
Ozgur M M,
et al.
Compa rison of MiECC and CPB in CABG
studies provided evidence supporting these theoretical
advantages. In a meta-analysis encompassing
2,770 patients from 24 studies, MiECC demonstrated
statistically significant superiority over conventional
bypass in terms of systemic inflammatory response
syndrome, hemodilution, and PRBC transfusion.[8]
This study covers our first cases and the adaptation
period of surgeons, anesthesiologists, anesthesia
technicians, and perfusionists during the transition
from a more open MIECC system to a completely closed
system. During this period, changes have occurred in
our approaches and awareness on issues such as blood
preservation, volume distribution, priming, heparin
use, ACT management, and cardioplegia management.
Over time, these changes have been reflected in our
clinical practice in both MiECC systems and standard
systems.
Po st op er at ive h e mo rr ha ge e x h i bit ed a n o te wo rt hy
reduction in the MiECC group; however, in contrast
to reported findings in the extant literature,
our investigation did not unveil a statistically
significant disparity. The reason might be the use
of type 2 or 3 MiECC systems in the initial period
and working at high ACT levels. Furthermore,
it is noteworthy that none of the patients in
the MiECC cohort necessitated reexploration due
to bleeding, whereas two patients in the CPB
group underwent reexploration. The dedication to
a conservative conventional CPB strategy, geared
towards mitigating volume overload, coupled with
an unwavering commitment to intensive bleeding
control protocols, likely played a role in the
comparatively marginal variance observed in
p o st op er at iv e dr ai na g e be tw ee n t he M iE CC a nd C PB
groups. Although this discrepancy failed to attain
statistical significance, the meticulous adherence to
these strategies underscores their potential impact
on mitigating adverse postoperative outcomes.
With the implementation of MiECC, blood
becomes less diluted, and the interaction between
blood and foreign bodies is minimized, resulting
in lower postoperative losses of Hct and Hgb.
Consequently, MiECC is recommended in both
general guidelines and blood conservation protocols
to minimize the reliance on blood products.[3-5] Ellam
et al.[9] observed a reduction in blood product usage
and postoperative Hgb loss with the adoption of
MiECC. In our investigation, we noted that MiECC
effectively preserved blood and its components during
cardiac surgery, leading to a significantly reduced
perioperative Hct difference compared to the control
group. However, the use of blood products led to a
convergence of Hgb and hemostatic values between
the two groups. Furthermore, the MiECC group
exhibited a substantial decrease in the utilization of
blood products throughout the entire hospitalization
period. These findings highlight the efficacy of
MiECC, specifically in anemic patients and those
undergoing CABG with a relatively higher distal
anastomosis count which correlates with current
literature.[9,10] However, there was no statistically
significant difference in the two patient groups on the
first, third, and fourth days after surgery. It is possible
for the blood products used in patients with decreased
Hgb to have an effect. Accordingly, significantly
more blood products were used in the conventional
group than in the MiECC group. In other words,
the similarity in postoperative days is due to the
difference in the use of blood products.
There are many reasons that affect blood
transfusion in on-pump CABG surgery. These factors
include the patient's age, general health condition,
anemia or clotting disorders, type and complexity of
heart surgery, type of surgical procedure, amount of
blood lost during surgery, and duration of surgery.
Postoperative factors that affect the need for blood
transfusion include chest tube drainage, systemic
infection, or multiorgan dysfunction.[11-13]
One of the methods suggested to reduce
postoperative transfusions is the use of cell
savers. According to the EACTS/EACTA/EBCP
guidelines, the use of cell savers in cardiac surgery
has positive effects.[14] Likewise, according to the
STS/SCA/AmSECT/SABM guidelines, positive
effects of cell saver in cardiac surgery were stated
with o ut cl ea r ef fe c ts o n m or ta lity and m o rb i d it y.[4] On
the other hand, it has been argued that large volumes
of salvaged blood may disrupt the coagulation
cascade.[15] In our study, the cell saver system was
used only in the MiECC group, and cardiotomy
suction was used only in the CPB group. Studies
showing the positive effects of cell saver use in terms
of transfusion generally compared the simultaneous
use of a cell saver with a cardiotomy suction or the
use of a cardiotomy suction alone. Therefore, when
comparing the two groups in our study, we cannot
clearly state whether the use of cell saver contributes
to positive results in terms of transfusion need.
Another method proposed to reduce intra- or
postoperative transfusion is autologous priming of
the on-pump system. Guidelines state that RAP is
a simple, safe, and effective process to decrease
intraoperative and postoperative transfusion rates
and should be done as much as possible.[4,14] In our
148
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2024;32(2):141-150
study, there was no significant difference between the
groups in terms of RAP. Therefore, we do not think
that this approach will lead to a significant difference
in terms of transfusion between the two groups.
Another significant finding from our study
pertains to the optimization of ACT value, which
aims to minimize the invasiveness of extracorporeal
circulation.[16] In the MiECC group, the mean
maximum ACT value recorded was 316±54 sec,
compared to 580±127 sec in the conventional CPB
group. Despite this substantial difference, neither
group experienced any thromboembolic events, such
as oxygenator or device-line thrombosis and stroke
or transient ischemic attack, and the surgeries were
safely completed. Existing literature suggests that
MiECC can be implemented at an ACT value of around
350 sec, whereas our study demonstrates that MiECC
can be safely conducted with lower ACT values.[17]
This demonstrates that MiECC utilization allows
for a more physiological and secure extracorporeal
circulation, marked by significantly lower ACT
values. This positions MiECC as a noteworthy
alternative for anticoagulation, particularly
beneficial for high-risk patients. Furthermore, the
findings suggest that on-pump coronary bypass
surgery can be safely conducted even with low ACT
values, underscoring the procedure's safety and lack
of complications.
As a secondary endpoint, we evaluated the length
of stay in both the inpatient service and the ICU. The
results indicated a shorter mean ICU stay with the
utilization of MiECC; however, we did not observe
a corresponding reduction in the length of stay in
the inpatient service. We believe that one of the
crucial factors influencing this lack of difference
in length of stay is the strict adherence to the
Enhanced Recovery After Surgery protocols at our
clinic, allowing for prompt patient discharge from
the fa ci lit y.[18]
Contrary to the existing literature, this study did
not reveal any inflammatory benefits associated
with the use of MiECC. In our clinic, pre- and
postoperative inflammatory markers, such as
interleukin-6 or tumor necrosis factor-alpha, were
not measured routinely. C-reactive protein is the
only inflammatory marker that was measured
routinely. Although preoperative CRP values were
significantly higher in the MiECC group, there
were no significant differences between groups in
the postoperative period. However, CRP can be
influenced by various confounding factors.[8,19]
Regarding renal outcomes, it is well documented
in the literature that MiECC is associated with a
reduced risk of renal injury and acute kidney injury,
and its impact on this outcome is also emphasized
in current clinical guidelines.[2 ,3, 4,8, 20] In this study,
we observed an incidence of acute kidney injury in
8.5% of the MiECC group and 14.5% of the CPB
group. Although the odds ratio of 1.69 was notable,
the analysis revealed that this difference did not
achieve statistical significance. Furthermore, we did
not observe any statistically significant difference
between postoperative creatinine values.
This study showed no significant difference
in troponin values between the MiECC and
conventional CPB groups, contrary to two studies in
the literature.[8, 21] We closely monitored cardioplegia
and troponin levels during conventional CPB, which
may have contributed to the lack of difference.
Additionally, there are numerous cofactors that can
trigger troponin elevation, and the present study
may not have had enough patients to overcome these
inherent differences.
The main limitations were that the study was
nonrandomized and retrospective and contained
a relatively limited sample size. The strength of
this article lies in its comprehensive comparison
of intraoperative and postoperative hemodynamic
data between two groups with similar preoperative
characteristics and a similar number of patients who
were operated on by the same surgical team in a short
period of time.
In conclusion, this study investigated the use
of minimal invasive extracorporeal circulation
compared to conventional conventional
cardiopulmonary bypass in patients undergoing
isolated coronary artery bypass surgery and revealed
significant advantages in terms of hematological
preservation and blood product utilization. The use
of minimal invasive extracorporeal circulation was
associated with a shorter length of stay in the intensive
care unit, lower perioperative hematocrit difference,
and a reduced need for transfusion of packed red blood
cells and fresh frozen plasma. Furthermore, minimal
invasive extracorporeal circulation allowed for the
optimization of activated clotting time, achieving a
more physiological extracorporeal circulation with
lower activated clotting time values, revealing an
alternative for patients at relatively high risk for
anticoagulation. Although this study had limitations,
it contributes to the growing body of evidence
supporting the use of minimal invasive extracorporeal
circulation in cardiac surgeries. Future research with
149
Ozgur M M,
et al.
Compa rison of MiECC and CPB in CABG
larger sample sizes is warranted to further explore the
potential benefits of minimal invasive extracorporeal
circulation and its impact on patient outcomes.
Ethics Committee Approval: The study protocol was
approve d by the Kartal Kosuyolu Hig h Specia l izat ion Training
and Research Hospital Clinical Research Ethics Committee
(date: 31.01.2023, no: 2023/02/666). The study was conducted
in accordance with the principles of the Declaration of
Helsinki.
Patient Consent for Publication: A written informed
consent was obtained from each patient.
Data Sharing Statement: The data that support the findings
of this study are available from the corresponding author upon
reasonable request.
Author Contributions: Concept and design: M.M.O.,
K.K.; Data collection: B.G., M.M.O., İ.Y., M.Ş.; Analysis and
interpretation of the data: M.M.O., M.A., K.K.; Drafting the
article: M.M.O.; Critical revision: K.K., S.S., T.O.; Visualisation:
T.O., S.S.
Conflict of Interest: The authors declared no conflicts of
interest with respect to the authorship and/or publication of this
article.
Funding: The authors received no financial support for the
research and/or authorship of this article.
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