A separate analysis of only strokes ipsilateral to the operated artery was also performed for each artery. However, the total number of strokes was very similar to the number of ipsilateral strokes, since in the majority of studies all the strokes were ipsilateral. Arterial complications such as occlusion, haemorrhage from the endarterectomy site, restenosis, infection at the operation site, or pseudoaneurysm formation were analysed for all arteries rather than patients. The analyses based on arteries assumed that, in patients who had bilateral endarterectomies, outcome events in each carotid artery were independent.
Main results: The previous version of this review included three trials involving 326 operations. Since then a further five trials have been reported, increasing the number of operations to 1480. Prior to 1995, all studies had compared vein closure with PTFE closure, but three of the later studies compared vein to Dacron grafts instead and one compared Dacron with PTFE. Allocation was not adequately concealed in two trials, and one only followed up patients to the time of hospital discharge. Intention to treat analysis was possible for six trials. In all but two trials a patient could be randomised twice and have each carotid artery randomised to different treatment groups. There were too few operative events to determine whether there was any difference between the vein and Dacron patches for perioperative stroke, death and arterial complications. The one study that compared Dacron and PTFE patches found a significant risk of combined stroke and transient ischaemic attack (p = 0.03) and restenosis at 30 days (p = 0.01), a borderline significant risk of perioperative stroke (p = 0.06), and a non significant increased risk of perioperative carotid thrombosis (p = 0.1) with dacron compared with PTFE. Five trials followed up patients for longer than 30 days. During follow-up for more than one year, no difference was shown between the two types of patch for the risk of stroke, death, or arterial restenosis. However, the number of events was small. Based on 15 events in 776 patients in four trials, there were significantly fewer pseudoaneurysms associated with synthetic patches than vein (odds ratio [OR] 0.09, 95% confidence interval [CI] 0.02 to 0.49) but the numbers involved were small and the clinical significance of this finding is uncertain.
Reviewers' conclusions: It is likely that the differences between different types of patch material are very small. Consequently, many more data than are currently available will be required to establish whether any differences do exist. Some evidence exists that PTFE patches may be superior to Colagen impregnated Dacron grafts in terms of perioperative stroke rates and restenosis. However the evidence is based upon data from a single, small trial and more studies that compare different types of synthetic graft are required to make firm conclusions. Psuedo aneurysm formation may be more common after use of a vein patch compared with a synthetic patch.
The GORE® ACUSEAL Cardiovascular Patch is designed for cardiovascular applications including cardiac, great vessel, and peripheral vascular repair and reconstruction. Advanced fluoropolymer technology enables our synthetic patch to seal around penetrating sutures and reduce suture line bleeding by as much as 88 percent.* This technology, combined with a low rate of restenosis, low thrombogenicity, improved suture retention, and multi-directional strength, sets the patch apart from the competition. The GORE-TEX® Suture is the ideal surgical companion when implanting the GORE® ACUSEAL Cardiovascular Patch.
Primary trends driving the vascular patches market are the rising incidence of CVD, growing geriatric population and subsequent prevalence of vascular diseases, rising number of cardiovascular surgeries worldwide, the availability of reimbursement for vascular procedures, growing adoption of biological patches.
Biologic patches are widely used for arterial closure during vascular and cardiac surgery. These patches have several advantages over their synthetic counterparts regarding biocompatibility and ease of use. They also minimize suture line bleeding and reduce the rates of infection.
Most children who are born with a clinically significant congenital heart defect (CHD) require palliative congenital heart surgeries utilizing native and artificial patch materials for the reconstruction of the heart and great vessels. A typical example of patch reconstruction surgery is the repair of vascular anomalies of the right side, as in the Tetralogy of Fallot (TOF) disease.2,13 In these operations, through the relief of main pulmonary artery (MPA) stenosis with an arterial patch, a balanced PA flow distribution is desired, which is influenced by the post-surgery conduit geometry and pressure levels. This task is further complicated by the large variability in patient-specific anatomy and the PA size. Unfavorable post-operative pulmonary hemodynamics may further result in abnormal pulmonary vascular remodeling.21 Therefore, the main objective of the present study is to develop a pre-surgical patch planning and biomechanical performance prediction system for TOF surgeries. It is hypothesized that this tool will assist the surgical team to achieve the best patch-reconstructed MPA conduit flow-pattern and mechanical stress customized for the individual patient in silico.
While the framework demonstrated in this paper is for MPA reconstruction, the methodology is equally applicable to the aortic patch repair surgeries (such as aortic coarctation and hypoplastic arch) with modifications on vessel dimensions, material property models and pre- post- operative loading.
In this paper, we present a pre-surgical, computer-aided surgical patch design framework for great arteries having arbitrary 3D stenosis sections. The proposed framework is validated through the actual surgical patch reconstructions performed on rapid-prototype replicas (Supplementary Material 1). This approach allows us to predict the intra- and post- operative anatomy, mechanical loading and the hemodynamics of the surgical reconstructions. It also allows the structural optimization of the reconstructed patch region before the surgical execution, leading improved performance. Particularly, pre-surgical planning of the 3D patch shape will reduce cardiopulmonary bypass time and consequently could influence the probability of post-operative complications.16,38
An idealized main pulmonary artery having symmetric stenosis leading to an asymmetric post-operative conduit after patch repair. The sequence of virtual surgical instances is illustrated in sequence. (a) Cutting an incision slit on the artery, (b) load-free state due to the release of residual stress after the incision, (c) intraoperative stretching of the incision gap for enlarging and deforming an initially flat patch to 3D shape that is tangent to the suture line curvature, (d) the suturing of patch to the artery (e) following cardiopulmonary bypass, the arterial pressure is established and the reconstructed PA conforms to its acute post-operative shape.
The finite element solver is validated experimentally, where the entire sequence of pre-operative surgical actions are replicated using a flexible rapid-prototype stenosis model (please see Supplementary Material 1). The rapid-prototype replica of Baseline case is patched using a Polytetrafluoroethylene (PTFE) material (Hemashield Gold Knitted Double Velour Vascular Graft, Maquet Getinge group, Rastatt, Germany) and tested in a mock-up static pressure set-up. The error in computed deformations is less than 2.7%, compared to the experimental post-op measurements.
Finite element and CFD simulations enabled the computation of multiple biomechanical performance indices, which are employed here to evaluate and compare the different patch designs and intra-operative strategies. These performance indices are listed below:
Figure 3 shows the 3D post-operative shape of designed patches for the cases in Length group. The effect of slit length on the post-operative shape of the patch is examined using the results of these cases. All patches are designed for a standard 16 mm-width initial gap opening. For the shorter slit length, a patch area of 488 mm2 is required which increases to 610 and 807 mm2 for Baseline and Length_2 cases, respectively. Likewise, the maximum stress value on these models increases from 135 to 239 kPa as the slit length is increased from 4 to 6 mm, respectively. For the case Baseline and case Length_2, maximum stress occurs at the artery while for case Length_1, the implanted patch bears the highest stress. As the slit length decreases, high stress regions extend further such that they overlap with the highly deformed cambered center region of the patch.
Implementing the patch to the stenosis region by using a single vessel opening recovers the narrowing of the vessel partly and remains the second half stenosed as shown in Fig. 2(b). To overcome this residual vessel narrowing effect, one approach is to patch both sides of the vessels with two identical patches instead of one as shown in Fig. 4(c). Indeed, the resulting post-operative patch reconstructions are relatively flatter compared to the single patch solution and are able to recover the stenosis almost fully on both sides of the artery. However, the total patch surface area increases 67% and the maximum stress on the patch rises from 119 to 216 kPa. Native vessel section also bare 95% higher maximum stress value compared to the Baseline configuration. 2b1af7f3a8