Long term results of elective aortic ascendens wrapping technique – single center study

Abstract

Background

The wrapping technique for the ascending aorta was developed for the treatment of high-risk patients. It is currently used to treat acute pathologies of the ascending aorta in patients with comorbidities or in high-risk situations. This study presents our long-term results with a standardized wrapping method.

Methods

This retrospective single-center study analyzed data on various aortic diseases from January 2008 to December 2018. The aim of this study was to evaluate the long-term results of the wrapping procedure, with a focus on aortic size as the primary endpoint. Mortality and cerebrovascular events are the secondary endpoints.

Results

The wrapping procedure was performed in 38 patients (16 female and 22 male patients, mean EuroScore II 4.9, range 2.0–18.7). The intended size of the ascending aorta was achieved through the use of Prolene mesh. The postoperative median diameter was 38 mm (preoperative median 5.50, range 4.3–7.1). During the follow-up period of 52.0 months (range 2.3–183.8), no recurrence of dilatation or need for reoperation was observed. Perioperative mortality and 1-year mortality were 0%.

Conclusions

The technique of covering the ascending aorta with a polypropylene mesh can be performed safely without the use of cardiopulmonary bypass. The technique allows for a predictable and stable diameter of the aortic wall without reintervention and with a longer follow-up period.

Introduction

The method of choice for treating an enlargement/aneurysm of the ascending aorta is replacement. The societies have made these recommendations in over the past several years [1–3]. Due to our positive and convincing results with wrapping technique of the ascending aorta, we have occasionally used this technique in selected high-surgical risk patients, in patients who did not want invasive surgery with the heart-lung machine for personal reasons or who have had contraindications for full heparinization [4].

The wrapping technique of the ascending aorta was initially developed for the treatment of high-risk patients [5, 6]. Currently, some articles focus on the treatment of acute pathologies of the ascending aorta in patients with comorbidities or in high-risk constellations [7–12].

So far, and despite some promising data, there is still only spare results published and no unity in the methods or material used.

In the following, we would therefore like to present our long-term results with a standardized wrapping method, that may support it use as an alternative treatment approach for ascending aorta pathologies.

Patients and methods

This retrospective observational study, in which the pre-, intra- and postoperative clinical and radiological data were analyzed descriptively, was performed in accordance with the institutional ethics committee (KEK BASEC No. 2021–02203). All patients provided informed written consent for the procedures and the analysis of all procedural data.

All data are available and obtained from the clinical information system of the University Hospital of Zurich (Dendrite Clinical System and KISIM 5.0.9.3). The data were compiled in Excel (Microsoft Corporation, Redmond, WA, USA) and prepared for statistical evaluation.

Patients

The patients presented here underwent surgery from January 2008 to December 2018 (Table 1). In all patients, the wrapping procedure (n = 38) was performed. Patient baseline characteristics are summarized in Table 2.

Table 1.

Demographic data preoperatively: wrapping only and wrapping + supra-aortic debranching (r = range)

Demography		Wrapping technique
N=		38
Male/Female		22/16
AGE	median	68.34 (r 43.4–86.6)
> 80 years		4/38 = 10.5%
urgency (30d mortality)	elective	36
	semi-elective	2
	urgent	0
	emergency	0
EURO-SCORE II	mean	4.9 (r 2.0–18.73)
NYHA	I/II/III/IV	20/12/4/0
CAD		14
Hypertension		37
Atrial fibrillation	permanent/interm	2/1
COPD		10
CVD		4
GFR %	median	68.50 (r 43–117)
LVEF %	median	59 (r 36–72)

Table 2.

Leading pathology with indication for surgery (several patients show mixed pathologies)

Aortic Pathologies	n = 38
♣ aneurysm of asc aorta isolated extended to arch (diameter < 50 mm) extended to desc aorta (diameter < 50 mm)	31 4 2
♣ following TEVAR (zone 3): arch aneurysm	1

Main inclusion criteria were use of multidetector computertomography-determined, various aortic pathologies and indication for treatment (Table 2). Outcomes and events were reported according to the end points.

The objectives of this study were the evaluation of the long-term results of the wrapping procedure focusing on the size of the aorta as the primary endpoint. Mortality and cerebrovascular events are the secondary endpoints.

The Surgical Concept of the Wrapping technique

As described previously, the surgical part is divided in the following steps [4].

In the following description, we would like to mention the products that we have used.

Following the full median sternotomy, the ascending aorta was fully exposed from the the sinotubular junction to the brachiocephalic trunk. Parallel a quadrangular polypropylene mesh was longitudinally marked according to the intended circumference, respectively corresponding aortic diameter.

The ascending aorta is surrounded by the polypropylene mesh (Prolene Polypropylene Mesh, 15 × 15 cm, Ethicon by J&J) and reduced to the before mentioned diameter (Fig. 1). We recommend a 2/0 polypropylene (Prolene 2 − 0 45 cm FS 8685 H, Ethicon by J&J) suture using for double layer running suture lines. Using the first horizontal mattress suture line, the mesh is fixed to the adventitia of the aortic wall. The second suture line is performed as an over and over suture line and provides additional stability.

Fig. 1.

Wrapping technique - intraoperative situs after WT: the arrow shows the mesh graft. Additional sutures are attached in the area of the inner and outer curvature to prevent the graft from slipping. Bottom right box: 3D reconstruction of the ascending aorta from the preoperative CT scan

Additional anchoring 4/0 Ticron (TI-CRON Polyester Suture, 4 − 0, Soft PTFE. MFID: 8886331431, Covidien) stitches fix the mesh at the medial and lateral sides at the sinotubular junction and at it cranial end avoiding a slipping of the mesh.

The procedure is performed without systemic heparinization.

In case of use of prolene mesh, special attention is required to orientate the mesh with is elastic property in the longitudinal axis and the stiffer property around the aorta.

The Criteria for indication and contraindication of the wrapping technique are listed in Table 3.

Table 3.

Criteria for the wrapping technique (WT):

Indication	Contraindication
♣ Indication for isolated WT of AA: diameter<70 mm originating distal to the sinotubular junction and ending proximally or just at the origin of the brachiocephalic trunk (BCT)	♣ absolute contraindication: calcified aorta or thrombi inside (risk of embolism!)
	♣ absolute contraindication: connective tissue disorders
	♣ dilatation of the aortic annulus or SJT
♣ Rapid growth and/or a family history of aortic rupture and/or dissection justified treatment even in patients with an ascending aortic diameter < 5 cm	♣ indication for other complex cardiac surgery e.g. coronary multivessel disease e.g. aortic or mitral valve stenosis or insufficiency 1
♣ In combination with TEVAR: landing zone is at least 4 cm
♣ ideally no previous operations
♣ elective or urgent indication - no emergency surgery (e.g. rupture in the aortic arch) to be discussed: type A aortic dissection
♣ variability of supraaortic branches is not important - excessive manipulations in aortic arch pathologies should be avoided (alternative: LSA using sandwich periscope technique)

(¹ a mild aortic valve insufficiency is well tolerated - in our own patient collective there was no patient in whom mild aortic insufficiency would have led to surgery at a later stage.)

Postoperative anticoagulation

Regarding the wrapping technique, postoperative anticoagulation is not mandatory, by may be required from other indications, e.g. thrombosis prophylaxis. By preserving the integrity of the intima, activation of the coagulation system is not to be expected.

Follow up

The follow-up computer tomography angiography (CTA) scan protocol includes an arterial and a venous phase scan in the first week, at 6 weeks, at 3, 6, and 12 months, and then annually [13]. If the constellation is stable, the follow-up frequency can be extended to 2 or 3 years. The CT images were analyzed independently by a senior radiologist and a senior cardiovascular surgeon. In case of divergency, final statement was achieved as a consensus after additional review.

If the follow-up was carried out in other hospitals, the CT scans were performed in accordance with our protocol. The examination results (clinical) and the evaluation of the CT examinations were always sent to us in written form. The images were forwarded to us electronically and evaluated by us.

Statistical analysis

The analysis was performed retrospectively on all data available for these patients at the clinical information system of the University Hospital of Zurich (Dendrite Clinical System and KISIM 5.0.9.3).

Descriptive data are presented as mean standard deviation and range, if appropriate. Nominal data are provided as counts and percentages. To adjust for the covariates age and gender, a Cox proportional hazards regression was performed to estimate the probability of survival (IBM SPSS Statistics 29/SPSS Inc., Chicago, IL, USA) (Figs. 2, 3).

Fig. 2.

Gender-related comparision of the pre- and postoperative aortic diameters and aortic index

Fig. 3.

Conditional on surgical technique: Plication (white arrows) more anteriorly and on the right side

Results

The wrapping procedure was performed in 38 consecutive patients (16 female and 22 male pt.). The median age is 68 (43–86) years.

Figure 4 shows the distribution of age, gender, and date of the last follow-up examination.

Fig. 4.

Distribution of gender in relation to the follow-up period

In all patients, regardless of presenting symptoms, the morphological outcome was documented postoperatively by angio-CT scan after wrapping procedure.

Primary endpoints

Size of the ascending aorta

The intended size of the ascending aorta can be achieved by adjusting and marking the Prolene mesh accordingly.

During the postoperative follow-up, a stable diameter of the ascending aorta was observed (intraop to last FU). Overall, the patients show a postoperative median diameter of 38 mm - our preferred and intended target size, especially when the arch may eventually require in future endovascular treatment extending into zone 0. No patient showed re-dilatation with the need for re-operation (Table 4).

Table 4.

Pre- & posteroperative aortic diameter (r = range)

Aortic diameter		Wrapping technique
ASC DIAMETER PRE	median	5.50 (r 4.3–7.1)
Ao Index (Dia/BSA) pre	median	3.03 (r 2.1–4.3)
ASC DIAMETER POST	median	3.80 (r 2.8–5.1)
AO INDEX (DIA/BSA) POST	median	2.07 (r 1.4–2.9)
DIFFERENCE PRE-POST	median	1.70 (r 0.7–2.5)

In addition, we calculated an aortic index to better compare the different aortic diameters in relation to body surface area. The comparison between the male and female patients also shows that the absolute values are not different, but the index shows a gender-dependent difference (Fig. 2).

Analysis of the very early postoperative CT-scans findings revealed in a few patients a plication of the aortic wall, especially in patients with larger diameters (> 50 mm) preoperatively (Fig. 3). Typically, these plications appeared on the ventral and outer curves. This can be explained by the fact that in all patients the aortic enlargement was more prominent ventrally as well at the outer curve. These plications disappeared during the follow-up period. Neurological complications caused by thrombus formations and embolism were not seen, especially not in these patients.

No dilation of the distal aorta or aortic arch was observed during follow-up examinations (independent CT scan evaluation by a radiologist and a member of our team). Furthermore, no reoperation/reintervention was necessary in any case.

Secondary Endpoint

I Perioperative mortality

Perioperative mortality and the 1-year-mortality rate in our patient population is 0%. The postoperative mortality is illustrated in Fig. 5.

Fig. 5.

Kaplan-Meier Analysis

The calculated mean EuroScore II was 4.9 (range 2.0–18.7) preoperatively. The operation was performed electively in 36 cases and urgently (< 24 h) in 2 patients.

In addition, we performed a Cox proportional hazards regression (Fig. 6) to examine the influencing factors of age and gender. Age showed a significance level of p = 0.021, while gender showed a significance level of p = 0.366.

Fig. 6.

Survival Probability (Cox Regression)

II Neurological complications

Clinical suspicion of spinal anterior syndrome was raised in one patient, who showed complete remission on the 2nd POD.

Overall, the postoperative course was uncomplicated (postoperative course Table 5). A postoperative low cardiac output (LCO: monitored cardiac index < 2.2 l/min/m², without associated relative hypovolemia and secondary to left and/or right ventricular failure) was detected in 2 (5.3%) patients. In both cases, the cause of LCO was an arrhythmia (atrial fibrillation and AV-block), that required temporarily medical support.

Table 5.

Treatment and postoperative Course (r = range)

Treatment and postoperative course		Wrapping technique
No. of Patients		38
postOPerative
LCO		2 (5.2%)
Renal failure		0
postop renal failure		0
GFR % POST	median	75.0 (r 37–136)
CVE		1 (transient) = 2.6%
mortality
30 d mortality		0
according to the urgency	Elective	36
	Urgent	2
	Emergency	0
	Salvage	0
ICU STAY (DAY)	median	1 (0–8)
Follow up	mean	52.0 (r 2.3–183.8)
Follow up > 1 year		30 (79%)

No complications were observed during the follow up (at our hospital) of mean 52.0 (range 2.3–183.8) months. All patients (100%) attended the first follow-up examination with CT scan at our hospital. In 79% of patients, the follow-up examinations were performed more than 1 year at our hospital. In 8 patients (21%), further follow-up (> 1 year) was carried out at their home location.

Discussion

The aim of our study was to analyze the long-term results of the wrapping technique of the ascending aorta as an alternative treatment approach for aortic pathologies.

As a result of our investigations, we were able to determine a 1-year mortality of 0% and stable diameters of the aorta after wrapping over the course of the follow-up.

There are numerous modifications to the wrapping technique [14–19]. Plonek has examined these in a meta-analysis and comes to similar results and conclusions as our study [20].

Current guidelines recommend replacement of the ascending aorta [2, 21]. In the previous European/STS Guidelines for ascending aortic surgery, the wrapping technique was not recommended as first line standard treatment [3]. The technique can be used “as an alternative to reduce the aortic diameter when aortic cannulation and cardiopulmonary bypass are either not possible or not desirable. This may be the case in elderly patients with calcified aorta, in high-risk patients” [3].

A calcified aorta is an absolute contraindication for this technique considering a diameter reduction is intended. This restriction of the indication of this technique is also supported by a meta-analysis [20]. But we used this technique without diameter reduction as an ad-hoc bailout treatment, in a case where intraoperative situs was considered highly inappropriate for conventional surgery.

However, and especially after the publication of a meta-analysis, it appears that there are no reports of increased mortality in patients or the need for re-do surgery after a wrapping procedure compared to patients after supracoronary graft replacement [20].

Regarding other wrapping techniques, the use of polypropylene mesh has critical advantage. Eventual bleeding produces by sutures is immediately visualized.

Potential Benefits of the Wrapping technique

The wrapping technique has several potential advantages, especially for high-risk patients or when used with other procedures.

I Less invasive and risk-reducing

It is considered a less complex procedure that can reduce operative, bypass, and cardiopulmonary bypass times [7, 22–25]. Some studies have shown that it results in shorter pump times, lower transfusion rates, and less postoperative atrial fibrillation compared to vessel replacement [26]. This can be explained by the absence of systemic anticoagulation and the use of a cardiopulmonary bypass.

II Optimization of the landing zone

Treating pathologies in the aortic arch is associated with many technical and anatomical challenges. The ideal landing zone for a stent graft in the aortic arch is considered to be a length of > 2 cm (proximal and distal) and a diameter of < 38/39 mm, in accordance with currently available endografts.

Example

Size of the prosthesis to be implanted (e.g., 45 mm) and the planned oversizing of the prosthesis by 15–20%. This results in a diameter of the “neo”-aorta of 35–38 mm. For the dimensions of the mesh (circumference of the “neo”-aorta), this means 110–120 mm.

However, an enlarged ascending aorta is an established exclusion criterion [10, 11, 27].

This technique optimizes the proximal landing zone for stent grafts in hybrid aortic arch operations. It offers reliable fixation, reduces the diameter, prevents proximal migration of the stent graft, and ensures a secure sealing zone. This reduces the risk of type I endoleaks [22, 27].

This makes endovascular repair possible even in patients who would otherwise be excluded due to an ectatic or dilated aorta.

Morphological finding of the aortic wall after wrapping

Wrapping part

The wrapping may lead to the formation of folds, or the aortic wall behaves like a “rubber band” and contracts after stress reduction.

Kolvenbach et al. observed a plication of the aorta after WT [28]. We also made this observation and explain it by the aortic wall surplus resulting when the diameter, respectively the circumference of large (> 50–55 mm) ascending aneurysm is reduced. That may occur in cases where the aortic has been overstretched and did lose it elasticity and therefore can’t recover to its original size when wrap is applied. Whatever, in our series plications were only discrete and disappeared during follow-up.

Plonek et al. have not observed this phenomenon and explained this with the “residual elasticity of moderately dilated aorta” [29]. They have performed a biomechanical analysis and have shown the reduction of wall tension following wrapping procedure. Later findings may be in line with our finding in larger aneurysms.

Non-Wrapping part

In this context, it is important to consider what happens to the non-wrapping aortic segments, especially the proximal aortic arch. While we did not observe any changes, and this has also been demonstrated by other authors [22], other authors have observed significant enlargements in the proximal aortic arch, which indicate the need for reintervention [30].

Material for Wrapping technique

It is worth to mention that we did not use a prosthesis for the wrapping as we were afraid by late ruptures that have been related to an erosion of the aortic wall by the graft [31, 32]. Possible causes include an interruption in the blood supply to the vasa vasorum of the tunica media; a chronic inflammatory response to foreign material; or compression of the aortic wall by opposing forces, such as external wrapping and aortic pressure. This compression could impair the metabolism of the aortic wall, leading to atrophy and sclerosis [33].

In our opinion, the use of a prolene mesh seems to be more appropriate. The mesh can be customized and is non-absorbable.

The measurement results from the mechanical tests show that prolene/polypropylene meshes can typically absorb tensile forces of several dozen newtons per cm in direct tension – well above the forces (a few newtons per cm bandwidth) that would occur solely due to blood pressure-induced wall stresses.

According to the manufacturer, it has a pore size of 1 mm, which allows connective tissue fibers to grow through it allow aortic wall to regenerate.

This hypothesis remains speculative because there are no patients in our series with re-operation and the option of histological examination. Notably, aortic dissection in the area repaired by wrapping has not been reported to date.

Limitations

One of the limitations of this study is the retrospective character of a relatively small population. Follow-up (> 1 year) is not 100%, which is due to the postoperative controls of the patients in their residential areas. A fact, which has been addressed in another publication [34]. For this reason, only limited statements can be made about the long-term stability of the wrapping technique.

In addition, propensity score matching is desirable for a larger number of cases in order to reduce selection bias.

Conclusion

The wrapping technique on the ascending aorta with a polypropylene-mesh can be perfomed safely without the use of cardiopulmonary bypass (including full heparinization and aortic cannulation). Our technique allows predictable diameter of the aortic wall, that is shown to remain stable with no re-intervention on the repaired spot in our updated series with longer follow-up period. This technique is therefore suitable for patients with an increased risk profile, among others. Finally, simplicity, quick learnability and thus controllability of this technique ensure safe implementation in daily practice.

Author contributions

M.H.: Writing – original draft, data acquisition & analysis. M.L.: Supervision, Methodology, Review, A.P.: Writing – review & editing, L.C.: Conceptualization, Writing – review & editing.

Funding

No external funding received.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Competing interests

The authors declare no competing interests. Mario Lachat reports being a consultant and proctor for Endospan since 2014 and CryoLife since 2019, as well as being a medical director for Endospan and holder of stock options since 2019.