Keywords
descending aortic replacement - thoracoabdominal aortic replacement - cardiopulmonary
bypass - left atrial-femoral bypass - aortic surgery - aortic aneurysm
Since the pioneering report by Magovern in 1989,[1] left heart bypass with a centrifugal pump and no oxygenator has long been established
as the key strategy for distal aortic perfusion during descending and thoracoabdominal
aortic (DTAA) replacement operations, mitigating the deleterious effects of the “clamp
and sew” technique.[2] Left heart bypass provides visceral, spinal cord, and lower limb perfusion while
the aorta is cross-clamped and requires only low-dose heparinization. However, in
this partial bypass circuit, intraoperative blood salvage is accomplished solely by
means of a cell saver, which preserves red blood cells but does not prevent loss of
platelets, plasma, and coagulation factors.[3]
The full cardiopulmonary bypass (CPB) circuit including the oxygenator, roller pumps,
and pump suckers has been proven to maintain oxygenation and hemodynamic stability
during cardiac and ascending or descending aortic operations and to provide immediate
blood return to the patient, while preserving plasma and clotting factors.[3] Aomi et al have previously reported a limited experience with DTAA repair using
left heart bypass with a centrifugal pump, an oxygenator, and a heat exchanger.[4] The purpose of this article is to describe our initial experience performing DTAA
replacement with a novel perfusion technique of left atrial-femoral artery (LA-FA)
or distal aortic full CPB with an oxygenator, roller pump, and pump suckers.
Methods
The circuit is shown in [Fig. 1]. The technique was conceived by our perfusionist (C.S.) after many years of performing
conventional LA-FA partial bypass with a centrifugal pump without an oxygenator. One-lung
ventilation is instituted. Inflow is taken from the superior or inferior pulmonary
vein with a right angle cannula (number 24, Edwards Lifesciences). Kinetic assisted
venous (LA) drainage (KAVD) is a technique in which a roller head is used to control
the rate of venous flow. A number 24 right angled cannula is connected to a primed
1/4″ line through a roller pump on the heart–lung machine and returned to the venous
reservoir. Blood passes through an oxygenator and heat exchanger and is propelled
by a roller pump back to the FA. Our perfusionists note that this system provides
optimal hemodynamic and circulatory capabilities. Shed blood is automatically and
immediately harvested into the pump suckers and returned to the pump. There is no
delay in processing through a cell saver device for later transfusion. Also, the perfusionists
can adjust the rate of left atrial drainage via roller pump as needed to leave enough
blood in the heart to provide the high upper body pressures required to optimize spinal
cord perfusion. They can independently adjust the flow through the other roller pump
to maintain the desired level of lower body perfusion. This permits immediate, appropriate
response to blood loss and other causes of hemodynamic instability.
Fig. 1 Left atrial-femoral full cardiopulmonary bypass circuit.
Full heparinization is used. Flows are adjusted to maintain a good upper body pressure
at or above 140 mm Hg during the cross-clamp time and to provide 2 to 4 L lower body
perfusion, dependent on body size. Left atrial return is adjusted to maintain these
parameters. Immediate harvesting and return of shed blood is accomplished via the
pump suckers.
Patient Population
Fourteen consecutive patients underwent descending or thoracoabdominal aortic replacement
under LA-FA (left-left) CPB with an oxygenator (CPB group) between October 2017 and
December 2018 at our institution. The CPB group was compared with 50 consecutive patients
who underwent DTAA replacement under traditional left heart bypass without an oxygenator
from February 2014 to October 2017 (LA-FA group).
Electronic medical records (EMRs) were reviewed to collect patients' demographics
and comorbidities, as well as preoperative, intraoperative, and postoperative parameters,
outcomes, and complications. Institutional Review Board approval was obtained from
Yale University's Human Investigation Committee. Informed consent was waived due to
the retrospective nature of the study.
Statistical analysis was conducted using Fisher's exact test for categorical data
and Student's t-tests for continuous data. Continuous variables are presented as mean ± standard
deviation and categorical variables are presented as numbers and percentages.
Patient demographics for the two groups are shown in [Table 1]. The mean patient age was 68.2 ± 7.2 years for the CPB group and 66.5 ± 12.7 years
for the LA-FA group. Three patients (21.4%) in the CPB group and 27 (54%) patients
in the LA-FA group were female. The CPB group consisted of eight (57.1%) patients
with nondissecting aneurysms, four (28.6%) patients with dissected aneurysms, one
(7.1%) patient with a pseudoaneurysm (as a result of a chronic traumatic aortic transection),
and one (7.1%) patient with penetrating ulcer of the aorta. In the LA-FA group, 27
(54%) patients presented with nondissecting aneurysms, 22 (44%) patients with dissected
aneurysms, and 1 (2%) patient with contained aortic rupture. Aortic pathology involved
only the descending aorta in 3 (21.4%) and 20 (40%) patients and the thoracoabdominal
aorta in 11 (78.6%) and 30 (60%) patients in the CPB and LA-FA groups, respectively.
Table 1
Patient demographics
|
CPB group (n = 14)
|
LA-FA group (n = 50)
|
p-Value (if applicable)
|
|
Age at the time of surgery
|
68.2 ± 7.2
|
66.5 ± 12.7
|
0.63
|
|
Female gender
|
N = 3 (21.4%)
|
N = 27 (54%)
|
|
|
Height (cm)
|
173.5 ± 11.2
|
168.4 ± 9.9
|
0.1
|
|
Weight (kg)
|
86.07 ± 16.9
|
76.7 ± 17.8
|
0.08
|
|
BMI (kg/m2)
|
28.6 ± 4.7
|
26.9 ± 5.1
|
0.28
|
Abbreviations: BMI, body mass index; CPB, cardiopulmonary bypass; LA-FA, left atrial-femoral
artery.
The Crawford classification with the Safi modification was used to assess the extent
of thoracoabdominal aortic aneurysms,[5] with the majority of TAAs falling under the most extensive type II category (N = 6 and N = 10 for the CPB and LA-FA groups, respectively). The maximal aortic diameter was
5.3 ± 1 cm for the CPB group and 5.8 ± 1.5 cm for the LA-FA group ([Table 2]).
Table 2
Diagnosis and related preoperative parameters
|
CPB group (n = 14)
|
LA-FA group (n = 50)
|
p-Value (if applicable)
|
|
Primary diagnosis
|
Nondissecting aneurysm, N = 8 (57.1%)
Dissected aneurysm, N = 4 (28.6%)
• Chronic type A dissection, N = 4 (100%)
Penetrating aortic ulcer, N = 1 (7.1%)
Aortic transection, N = 1 (7.1%)
|
Nondissecting aneurysm, N = 27 (54%)
Dissected aneurysm, N = 22 (44%)
• Chronic type A dissection, N = 8 (36.4%)
• Type B dissection, N = 14 (63.7%) (acute/subacute, N = 3; chronic, N = 11)
Contained rupture, N = 1 (2%)
|
|
|
Location of primary diagnosis
|
Thoracoabdominal, N = 11 (78.6%)
Descending, N = 3 (21.4%)
|
Thoracoabdominal, N = 30 (60%)
Descending, N = 20 (40%)
|
|
|
Crawford classification
|
Crawford 1, N = 3
Crawford 2, N = 6 (54.5%)
Crawford 4, N = 1
Crawford 5, N = 1
|
Crawford 1, N = 11
Crawford 2, N = 10 (33.3%)
Crawford 3, N = 4
Crawford 4, N = 1
Crawford 5, N = 4
|
|
|
Maximal aortic diameter
|
5.3 ± 1
|
5.8 ± 1.5
|
0.2
|
Abbreviations: CPB, cardiopulmonary bypass; LA-FA, left atrial-femoral artery.
Medical and surgical history for both groups is shown in [Table 3]. Comorbidities were more prevalent in the CPB group, as illustrated in [Fig. 2], with the most significant difference observed in coronary artery disease, in 10
(71.4%) patients in the CPB group and 17 (34%) patients in the LA-FA group (p = 0.01). Six patients in the CPB group (42.9%) had a confirmed family history of
thoracic aortic disease as documented by a relative having undergone imaging or surgical
repair, versus 9 (18%) patients in the LA-FA group (p = 0.07). Furthermore, 9 (64.3%) patients in the CPB group and 40 (80%) patients in
the LA-FA group had a prior history of open or endovascular aortic operation. Also,
3 (21.4%) and 13 (26%) patients, respectively, had had a previous cardiac surgery
(non aortic).
Fig. 2 Radar plot showing patient comorbidities for CPB and LA-FA groups. Note higher complexity
of CPB group. CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease;
CPB, cardiopulmonary bypass; LA-FA, left atrial-femoral artery.
Table 3
Previous medical and surgical history of patients in the CPB and LA-FA groups
|
CPB group (n = 14)
|
LA-FA group (n = 50)
|
p-Value
|
|
Hypertension
|
14 (100%)
|
48 (96%)
|
1
|
|
Diabetes
|
3 (21.4%)
|
7 (14%)
|
0.68
|
|
Dyslipidemia
|
9 (64.3%)
|
31 (62%)
|
0.89
|
|
Obesity
|
9 (64.3%)
|
22 (44%)
|
0.75
|
|
Chronic obstructive pulmonary disease
|
5 (35.7%)
|
12 (24%)
|
0.49
|
|
Renal failure
|
2 (14.3%)
|
8 (16%)
|
1
|
|
Coronary artery disease
|
10 (71.4%)
|
17 (34%)
|
0.01
|
|
Marfan's syndrome/connective tissue disorder
|
0
|
3 (6%)
|
0.59
|
|
History of smoking
|
12 (85.8%)
|
30 (60%)
|
0.11
|
|
Other vascular abnormality
|
11 (78.6%)
|
39 (78%)
|
1
|
|
Previous cardiac surgery (nonaortic)
|
3 (21.4%)
|
13 (26%)
|
1
|
|
Previous aortic surgery (open)
|
7 (50%)
|
34 (68%)
|
0.34
|
|
Previous aortic endovascular surgery
|
4 (28.6%)
|
8 (16%)
|
0.44
|
|
Confirmed family history of aortic disease
|
6 (42.9%)
|
9 (18%)
|
0.07
|
Abbreviations: CPB, cardiopulmonary bypass; LA-FA, left atrial-femoral artery.
Note: The bold values are the ones in which p < 0.05.
Operative Data
Operative data are summarized in [Table 4]. Descending aortic replacement was performed in 8 (57.1%) and 32 (64%) patients
and thoracoabdominal aortic replacement was performed in 6 (42.9%) and 18 (36%) patients
in the CPB and LA-FA groups, respectively. The operation was elective in 13 (92.9%)
and 46 (92%) patients and urgent in 1 (7.1%) and 4 (8%) patients in the two groups,
respectively. Extracorporeal circulation time was 62.5 ± 27.2 and 53.6 ± 23.1 minutes,
respectively (p = 0.23). Aortic cross-clamp time was higher in the CPB group (66.9 ± 24.1 vs. 50.6 ± 19 minutes,
p = 0.01). The mean arterial blood oxygen saturation (SpO2%) during bypass time was maintained at high levels in both CPB and LA-FA groups (97.8 ± 6.8
vs. 97.2 ± 5, p = 0.8).
Table 4
Operative data for CPB and LA-FA groups
|
CPB group (n = 14)
|
LA-FA group (n = 50)
|
p-Value (if applicable)
|
|
Operation—emergent, urgent, elective
|
Elective, N = 13 (92.9%)
Urgent, N = 1 (7.1%)
|
Elective, N = 46 (92%)
Urgent, N = 4 (8%)
|
|
|
Surgery replacement—descending, thoracoabdominal
|
Descending, N = 8 (57.1%)
Thoracoabdominal, N = 6 (42.9%)
|
Descending, N = 32 (64%)
Thoracoabdominal, N = 18 (36%)
|
|
|
Cannulation site (to pump)
|
Pulmonary vein, N = 14 (100%)
|
Pulmonary vein, N = 50 (100%)
|
|
|
Cannulation site (from pump)
|
Femoral artery, N = 6 (42.9%)
Distal aorta, N = 6 (42.9%)
Left iliac artery, N = 2 (14.3%)
|
Femoral artery, N = 36 (72%)
Distal aorta, N = 13 (26%)
Right iliac artery, N = 1 (2%)
|
|
|
Surgery—additional concomitant procedure (e.g., wedge lung resection, subclavian artery
reconstruction, among others)
|
11(78.6%)
|
31 (62%)
|
0.35
|
|
Extracorporeal circulation time (min)
|
62.5 ± 27.2
|
53.6 ± 23.1
|
0.23
|
|
Aortic cross-clamp time (min)
|
66.9 ± 24.1
|
50.6 ± 19
|
0.01
|
|
Mean SpO2 during bypass time (%)
|
97.8 ± 6.8
|
97.2 ± 5
|
0.8
|
|
Number of RBC units transfused intraoperatively
|
2.21 ± 3.2
|
5.88 ± 4.2
|
0.004
|
|
Number of platelet units transfused intraoperatively
|
1.29 ± 1.1
|
1.02 ± 0.8
|
0.32
|
|
FFP/cryoprecipitate transfused intraoperatively
|
N = 10 (71.4%)
|
N = 44 (88%)
|
0.21
|
|
Factor VII transfused intraoperatively
|
N = 2 (14.3%)
|
N = 2 (4%)
|
0.21
|
|
Number of vasopressors infused intraoperatively
|
1.93 ± 0.9
|
0.98 ± 1
|
0.002
|
|
Number of bolus inotropes injected intraoperatively
|
2 ± 1.5
|
1.54 ± 1.1
|
0.2
|
|
Total number of minutes when SBP was below 80 mm Hg intraoperatively
|
14.4 ± 13.8
|
16.8 ± 18.9
|
0.66
|
|
Cell saver volume (mL)
|
1,518.6 ± 1,691.7
|
2,653 ± 1,805
|
0.04
|
|
Motor evoked potentials—preserved/transient decrease/permanent loss
|
Preserved, N = 6 (42.9%)
Transient decrease, N = 8 (57.1%)
|
Preserved, N = 27 (54%)
Transient decrease, N = 15 (30%)
Permanent loss, N = 1 (2%)
|
|
Abbreviations: CPB, cardiopulmonary bypass; FFP, fresh frozen plasma; LA-FA, left
atrial-femoral artery; RBC, red blood cells; SBP, systolic blood pressure; SpO2, peripheral capillary oxygen saturation.
Note: The bold values are the ones in which p < 0.05.
Patients who underwent DTAA replacement under full left atrial-femoral bypass with
an oxygenator required significantly fewer red blood cell (RBC) transfusions intraoperatively
than the LA-FA group (2.21 ± 3.2 vs. 5.88 ± 4.2 units, p = 0.004; [Fig. 3]). The CPB and LA-FA groups did not substantially differ in platelet transfusions
(1.29 ± 1.1 vs. 1.02 ± 0.8, p = 0.32), fresh frozen plasma/cryoprecipitate transfusions (10 [71.4%] vs. 44 [88%]
patients, p = 0.21), factor VII transfusions (2 [14.3%] vs. 2 [4%] patients, p = 0.21), or bolus inotrope injections intraoperatively (2 ± 1.5 vs. 1.54 ± 1.1, p = 0.2). However, patients in the CPB group required significantly more vasopressor
infusions in the operating room (1.93 ± 0.9 vs. 0.98 ± 1, p = 0.002). Both groups remained hemodynamically stable, as the average total time
when the systolic blood pressure was below 80 mm Hg intraoperatively was 14.4 ± 13.8 minutes
for the CPB group and 16.8 ± 18.9 minutes for the LA-FA group (p = 0.66). The cell saver volume was significantly reduced in the CPB group (1,518.6 ± 1,691.7
vs. 2,653 ± 1,805 mL, p = 0.04).
Fig. 3 Kernel density plot of number of intraoperative RBC transfusions in the CPB and LA-FA
groups. CPB, cardiopulmonary bypass; LA-FA, left atrial-femoral artery; RBC, red blood
cell.
Postoperative Parameters and Operative Outcome
Postoperative Parameters and Operative Outcome
Total blood loss from arrival at the ICU until 7 a.m. the day following the operation
was 1,445.7 ± 1,061.3 mL for the CPB group and 1,094.5 ± 940.3 mL for the LA-FA group
(p = 0.23; [Table 5]). The mean lowest systolic blood pressure the first night after the operation was
107.1 ± 14.9 mm Hg for the CPB group and 111.7 ± 18.5 for the LA-FA group (p = 0.4). There was no significant difference observed between the CPB and LA-FA groups
in terms of postoperative INR (1.41 ± 0.4 vs. 1.32 ± 0.35, p = 0.3) and postoperative PTT (45.5 ± 22.1 vs. 37.7 ± 19.5, p = 0.2). The CPB group had significantly lower postoperative RBC count (3.3 ± 0.6
vs. 4.0 ± 0.7 cells/μL, p = 0.0001) and hematocrit values (30.2 ± 4.3 vs. 35.8 ± 6.2, p = 0.002). However, these patients did not require a significantly higher amount of
transfusions postoperatively, with an average of 3.3 ± 3.2 RBC units required, as
compared with 1.6 ± 4.4 RBC units for the LA-FA group (p = 0.19), as well as 0.9 ± 1.1 versus 1.1 ± 1.9 platelet units (p = 0.78). Fresh frozen plasma or cryoprecipitate transfusion was required in 8 (57.1%)
and 20 (40%) patients (p = 0.36), and factor VII was transfused in 4 (28.6%) and 6 (12%) patients (p = 0.2) in the CPB and LA-FA group, respectively.
Table 5
Postoperative parameters for CPB and LA-FA groups
|
CPB group (n = 14)
|
LA-FA group (n = 50)
|
p-Value (if applicable)
|
|
Total blood loss until 7 a.m. on postoperative day 1 (mL)
|
1,445.7 ± 1,061.3
|
1,094.5 ± 940.3
|
0.23
|
|
Lowest SBP the night after surgery
|
107.1 ± 14.9
|
111.7 ± 18.5
|
0.4
|
|
Number of vasopressors infused on the first postoperative night
|
0.9 ± 1.2
|
0.5 ± 0.8
|
0.14
|
|
Temperature at ICU arrival
|
35.9 ± 1.1
|
35.8 ± 0.8
|
0.65
|
|
Postoperative INR
|
1.41 ± 0.4
|
1.32 ± 0.35
|
0.4
|
|
Postoperative PTT
|
45.5 ± 22.1
|
37.7 ± 19.5
|
0.2
|
|
Postoperative RBC count
|
3.3 ± 0.6
|
4.0 ± 0.7
|
0.0001
|
|
Postoperative hematocrit
|
30.2 ± 4.3
|
35.8 ± 6.2
|
0.002
|
|
Number of RBC units transfused postoperatively
|
3.3 ± 3.2
|
1.6 ± 4.4
|
0.19
|
|
Number of platelet units transfused postoperatively
|
0.9 ± 1.1
|
1.1 ± 1.9
|
0.78
|
|
Fresh frozen plasma transfused postoperatively
|
N = 8 (57.1%)
|
N = 20 (40%)
|
0.36
|
|
Factor VII transfused postoperatively
|
N = 4 (28.6%)
|
N = 6 (12%)
|
0.2
|
Abbreviations: CPB, cardiopulmonary bypass; ICU, intensive care unit; INR, international
normalized ratio; LA-FA, left atrial-femoral artery; PTT, partial thromboplastin time;
RBC, red blood cells; SBP, systolic blood pressure.
Note: The bold values are the ones in which p < 0.05.
Postoperative outcomes are summarized in [Table 6]. Patients were followed up clinically at 30 days to assess mortality and duration
of hospitalization, as well as postoperative complications. Thirty-day mortality included
only one (7.1%) patient from the CPB group and seven (14%) patients from the LA-FA
group (p = 0.67). No patients in the CPB group suffered paraparesis or paraplegia, compared
with three (6%) patients in the LA-FA group (p = 0.59). Three (21.4%) patients in the CPB group required a reexploration operation
for bleeding, compared with three (6%) patients in the LA-FA group (p = 0.11). Other postoperative morbidities for the CPB and LA-FA groups, respectively,
included stroke in 1 (7.1%) and 4 (8%) patients, atrial fibrillation in 7 (50%) and
10 (20%) patients (p = 0.04), prolonged ventilation (more than 48 hours) in 2 (14.3%) and 9 (18%) patients,
pulmonary complications in 5 (35.7%) and 17 (34%) patients, and renal dysfunction
requiring dialysis in 2 (14.3%) and 4 (8%) patients (p = 0.6). Average hospital stay duration was 15.7 ± 10 days for the CPB group and 11.9 ± 9.4
days for the LA-FA group (p = 0.2).
Table 6
Early mortality, morbidity, and hospital stay duration for CPB and LA-FA groups
|
CPB group (n = 14)
|
LA-FA group (n = 50)
|
p-Value
|
|
30-d mortality
|
1 (7.1%)
|
7 (14%)
|
0.67
|
|
Stroke
|
1(7.1%)
|
4 (8%)
|
1
|
|
Paraplegia
|
0
|
3 (6%)
|
0.59
|
|
Seizures
|
0
|
0
|
1
|
|
Atrial fibrillation
|
7 (50%)
|
10 (20%)
|
0.04
|
|
Prolonged ventilation (>48 h)
|
2 (14.3%)
|
9 (18%)
|
1
|
|
Pulmonary complications
|
5 (35.7%)
|
17 (34%)
|
1
|
|
Renal dysfunction requiring CRRT or dialysis
|
2 (14.3%)
|
4 (8%)
|
0.6
|
|
Reexploration for bleeding
|
3 (21.4%)
|
3 (6%)
|
0.11
|
|
Hospital stay duration (d)
|
15.7 ± 10
|
11.9 ± 9.4
|
0.2
|
Abbreviation: CCRT, continuous renal replacement therapy; CPB, cardiopulmonary bypass;
LA-FA, left atrial-femoral artery.
Note: The bold values are the ones in which p < 0.05.
The surgeon's intraoperative strong impression was that hemodynamics and oxygenation
were easily maintained, likely reflecting immediate harvesting and transfusion of
shed blood.
Discussion
Despite the progress in DTAA surgery, the appropriate perfusion strategies for preventing
severe complications such as spinal cord ischemia and end-organ dysfunction remain
controversial. Some studies have shown that left heart bypass has reduced incidence
of paraparesis and paraplegia from 39 to 10% in type II cases and has led to a significant
decrease in postoperative renal failure.[6]
[7]
[8]
[9]
[10] Others have demonstrated that left heart bypass produces no concrete advantage over
the “clamp and sew” technique, especially in terms of spinal cord injury.[11]
[12] Some authors have also reported favorable outcomes with the routine use of full
arteriovenous CPB[13] and total circulatory arrest[14] during DTAA repair.
In our experience, left atrial-femoral bypass with an oxygenator is safe and represents
an interesting alternative to traditional left heart bypass during DTAA operations.
The merits and demerits of the novel perfusion technique compared with conventional
left heart bypass are shown in [Table 7]. All patients remained hemodynamically stable intraoperatively, as the use of the
cardiotomy reservoir and the pump suckers permitted blood salvage and immediate return
to the patient. Kinetically enhanced drainage permitted excellent hemodynamic modulation.
Full-dose CPB heparin was reversed without difficulty and there were no CPB circuit-related
intraoperative complications.
Table 7
Merits and demerits of novel perfusion with roller pump and oxygenator, compared with
conventional LA-FA bypass
|
CPB (LA-FA with oxygenator)
|
Conventional LA-FA bypass (no oxygenator)
|
|
Benefits
|
|
Immediate harvest and return of shed blood
|
Delay in return of shed blood due to cell saver processing
|
|
Preservation of coagulation components lost in plasma removal by cell saver
|
Loss of coagulation components in plasma removed by cell saver
|
|
Oxygenation of desaturated blood from “down” lung
|
No contribution to oxygenation
|
|
Smooth, secure hemodynamics (strong clinical impression)
|
|
|
“Kinetically enhanced” drainage
|
None
|
|
Liabilities
|
|
Full heparinization
|
Low-dose heparinization
|
|
Increased complexity
|
Simplicity
|
Abbreviations: CPB, cardiopulmonary bypass; LA-FA, left atrial-femoral artery.
Aomi and colleagues have previously reported their experience performing DTAA replacement
using a centrifugal pump (ours was a roller pump), an oxygenator and a heat exchanger
in 25 patients and standard left heart bypass in 45 patients. The authors demonstrated
that the group with the oxygenator experienced significantly less intraoperative blood
loss (p < 0.01) and required significantly fewer blood transfusions (p < 0.05). Thus, their experience was similar to ours. Our experience also showed that
the CPB group required significantly fewer RBC transfusions compared with the LA-FA
group (2.21 vs. 5.88, p = 0.004; [Fig. 3]). These patients also had markedly reduced cell saver volume (1,518.6 vs. 2,653 mL,
p = 0.04), confirming the salvage of plasma through the use of the full heart–lung machine.
Aomi et al also reported that their method showed an oxygenation advantage; patients
in our CPB group also maintained superb oxygenation at all times.[4] We felt that directly draining and oxygenating desaturated blood from the “down”
lung produced reliable and beneficial high oxygenation.
In our series, the patients in the CPB group presented with greater comorbidities
than the LA-FA group ([Fig. 2]), with the largest difference observed in coronary artery disease (p = 0.01). A study by Coselli et al evaluating the outcomes of DTAA replacement in
3,309 patients showed that coronary artery disease increases risk of paraplegia and
paraparesis in Crawford type I and II repairs,[15] such as the cases performed in the majority of patients in our CPB group. Furthermore,
the CPB group had significantly longer aortic cross-clamp times (66.9 ± 24.1 vs. 50.6 ± 19 minutes,
p = 0.01), likely indicating increased operation complexity in this group. Despite
the greater burden of CAD and more complex surgical procedures, not a single case
of paraplegia was observed in this group, which could be interpreted as a benefit
of the novel full LA-FA bypass technique. Reliably superb oxygenation maintenance
may contribute to cord protection. Early mortality included only one complex patient
in the CPB group (7.1%) and 7 patients (14%) in the LA-FA group, indicating excellent
safety for the novel full LA-FA bypass technique.
Study Limitations
We have presented a favorable but limited experience with the novel technique of left
atrial-femoral CPB with an oxygenator for DTAA surgery. More cases and a longer follow-up
are necessary to ascertain more fully the benefits and disadvantages of this perfusion
strategy for DTAA replacement. We did not compare with full CPB with drainage from
the right atrium, which has been used for decades in such operations but fallen behind
in usage after the advent of LA-FA bypass with a centrifugal pump. Our technique avoids
the need for groin dissection and passage of a long venous line to the RA. Also, with
full bypass, issues of cardioplegia and upper and lower body arterial cannulation
may arise, depending on team preferences and policies.
Conclusion
Traditional LA-FA bypass without an oxygenator avoids high-dose heparin. Our experience
finds that in the present era, when heparin reversal is more secure, application of
full left atrial-femoral bypass with an oxygenator is safe. This novel technique,
which includes a venous reservoir, a roller pump with pump suckers, and an oxygenator,
permits immediate blood retrieval and salvage of the plasma and coagulation factors
lost in the cell saver with the traditional LA-FA bypass, while maintaining arterial
oxygenation levels. Our initial clinical impression is that the novel CPB technique
with an oxygenator provides significant advantages, and we suggest that surgeons explore
this technical option.
