Experimental Study of Aortic Anastomosis Using a Circular Stapling Device in the Porcine Model

Α systematic review and meta-analysis of the efficacy of aortic anastomotic devices

OBJECTIVE

One of the factors contributing to complications related to open repair of the aorta is the construction of a hand-sewn anastomosis. Aortic anastomotic devices (AADs), such as the intraluminal ringed graft (IRG), and the anastomotic stenting technique have been developed to perform a sutureless and less complicated anastomosis. This study performed a systematic review and meta-analysis of the literature reporting clinical use of AADs and aimed to assess, primarily, the effect of each device on 30-day overall and operation-related mortality and aortic cross-clamping time and, secondarily, the rate of successful two-sided application of the IRG device and the operation-related morbidity for each device.

METHODS

An electronic search was performed using MEDLINE, Scopus, ScienceDirect, and Cochrane Library by two independent authors. Our exclusion criteria included studies incorporating fewer than three patients and studies reporting results solely from animals or in vitro testing, results solely from end-to-side anastomosis, and results solely from endarterectomy procedures. The last search date was February 1, 2018.

RESULTS

A total of 41 studies were identified that reported outcomes for the use of three different device types: IRG, anastomotic stenting technique, and surgical staplers. The last two types were classified together as the non-IRG group. The meta-analysis included 27 studies with 50 cohorts incorporating 1260 patients. The median age of the incorporated patients was 61.4 years (range, 51-73 years), and 68.9% were male. The operations were performed for the treatment of acute aortic dissection in 82.3%. The pooled overall 30-day mortality rate varied by device type; IRG devices had a mean rate of all-cause mortality of 9.71%, whereas non-IRG devices were associated with a significantly (I2 = 15.78%; P for Cochrane Q test < .19) lower rate of death (1.47%). The pooled mean aortic cross-clamping time was 35.83 minutes. Metaregression showed that the performance of two-sided anastomosis with the IRG device significantly decreased the aortic cross-clamping time. However, a successful two-sided ringed anastomosis was performed in approximately half of the cases.

CONCLUSIONS

Taking into account that the majority of operations were performed for the treatment of acute aortic dissection, AADs had a relatively low rate of 30-day mortality. Despite the observed heterogeneity in study protocols and the small sample size in the non-IRG group, the non-IRG group presented with the lowest 30-day mortality rate. Specific device-related complications between the different device types need further investigation.

Preliminary experimental study of a mechanical connector allowing vascular anastomosis

BACKGROUND

Aortic clamping time needed to carry out anastomosis during aortic surgery is one of the major predictive factors of morbidity/mortality. Because of the difficulties inherent in this technique, the duration of aortic clamping can be increased significantly with laparoscopy, which may explain why this kind of surgery is not often undertaken. We designed an original connector that will help us perform automated end-to-end vascular anastomoses. This anastomotic device was tested on a cadaver, test benches, and finally on pigs.

METHODS

The connector consists of a bare-metal stent with spikes covering its outer surface. Once the prosthesis has been introduced into the arterial lumen over a 15-mm length, the connector is placed into the prosthesis; then, upon inflating a balloon and employing stent spikes, the prosthesis can be anchored in the artery. A feasibility study was carried out, first on cadaveric arteries and then on bench tests. In vivo, using this connector, the infrarenal aorta of 7 pigs was replaced with a 6-8-mm-diameter prosthesis. One to 42 days after implantation, angiography was performed before explanting the prosthesis. Evaluation criteria included anastomosis performance time, leakproofing capacity, tensile strength, patency, and histologic changes induced by the device.

RESULTS

On the cadavers, manual traction tests showed that the anastomoses were satisfactory. Median force needed to rupture an automated anastomosis was 15.85 N. No leakage was seen under a systolic/diastolic pressure of up to 250/180 mm Hg. All pigs benefited from automated anastomosis. Once the designed device had been assessed, the median connection time was 2 minutes. In 4 cases, aortic thrombosis was found, 1 of which was septic. The implanting ancillary was responsible for 2 posterior aortic wall perforations, which extended the clamping time; therefore, this device should be modified. Anastomosis patency and tensile strength tests were satisfactory. Histologic results showed the connector incorporation, integration of the spikes in the arterial wall, and the absence of inflammation in the aortic wall.

CONCLUSIONS

These preliminary studies confirm that the connector is quick and reliable for performing in vivo arterioprosthetic anastomoses. Further studies are needed to improve the ancillary device, which will enable its use it in laparoscopic and conventional surgery.

Trial of new vascular clips for aortic anastomosis in a canine model

OBJECTIVES

We created a new vascular clip designed for aortic surgery. The purposes of this investigation were to examine surgical applicability in a clinically relevant aortic replacement model and to assess biomechanical strength of the clipped anastomosis and serial histologic changes in the clipped anastomotic site.

METHODS

Twenty-one beagles underwent descending thoracic aortic replacement. Distal anastomosis was performed with the new clips, mimicking the cuffed anastomosis technique, and proximal anastomosis was carried out by conventional suture anastomosis. Tissue specimens of the anastomotic sites were harvested at 1, 3, 6, and 12 months postoperatively for examination.

RESULTS

There was no significant difference in the time required to carry out clip anastomosis (12.2 +/- 1.3 minutes) and suture anastomosis (13.7 +/- 0.9 minutes; P = .38). Neither type of anastomotic site was disrupted by raising the intraluminal pressure to 280 mm Hg. Microscopically, the areas of aortic wall compressed by vascular clips appeared as hyalinized areas adjacent to surrounding collagen fibers, with no significant infiltration of inflammatory cells. Identical histologic changes were observed at the site of the sutured anastomosis. The media at the clipped anastomosis site was significantly thinner than that at the sutured anastomosis site at 1 month after the operation. However, there was no significant difference in the thickness of the media at 3 months.

CONCLUSIONS

The new vascular clips were effective in this clinically relevant model, with appropriate biomechanical strength, and the anastomotic sites underwent similar histologic changes to those observed after suture anastomosis.

Experimental Study of a Novel Suture-less Aortic Anastomotic Device

OBJECTIVES

To assess the suitability and safety of a novel suture-less hermetic docking head (HDH) device for aortic anastomosis, and to test it in vitro, on cadavers, and in animals.

DESIGN

Uncontrolled prospective studies.

MATERIALS

HDH device with commercial vascular grafts.

METHODS

Two experimental series were conducted in vitro to test the hermetic seal of the anastomosis and the fixation of the device. Another series was performed in 6 cadavers with atherosclerotic aortas. Two in vivo trials tested the HDH device when implanted in ten and five pigs, respectively, with follow-up of 22 weeks. Pathological, histological and radiographic studies of the aorta were performed.

RESULTS

The in vitro and cadaveric studies demonstrated the resilience of the device under physiological and extreme conditions (up to 1200mmHg pulsatile flow on the bench and up to 270mmHg in cadaveric studies). These studies also established the safety and ease of application of the device in both normal and atherosclerotic aortas. Insertion was easy and rapid. There was no indication of leakage, narrowing or stenosis at the anastomotic sites. The implants' position was maintained without distal or proximal migration. Reliable fixation was observed despite significant increase (up to 112%) in the weight of the animals. Histologically, normal tissue reaction of the lamina was observed.

CONCLUSIONS

The suture-less HDH device's behavior in vitro and in vivo suggests that this implant is useful for aortic anastomosis, and its use is faster and simpler than common suturing techniques.

Intravascular Stapler for “Open” Aortic Surgery: Preliminary Results

OBJECTIVES

The aim of this study was to assess the efficacy of a new stapling device using a pig model.

METHODS

Straight 12 mm Gore-Tex grafts were inserted end to end into the aorta of 12 pigs. One anastomosis was performed with the stapler and the other using 4/0 prolene sutures and 13 mm needles. The animals were sacrificed at one week, one and three months and all grafts underwent histological examination. Leakage from the anastomoses was assessed in a separate specially designed circulation model using saline as a perfusate.

RESULTS

The stapled anastomoses took 1.0+/-0.25 minutes to complete while suturing took 8.5+/-1.5 minutes. There was no difference in the histology between the two types of anastomosis. The leak rate was six times greater at the sutured compared to the stapled anastomosis.

CONCLUSION

The use of stapled anastomoses may allow a significant shortening of aortic cross clamping time, reduce anastomotic leakage and may be particularly useful in laparoscopic aortic repair. A randomised trial is required to assess the efficacy of this device.