Hybrid and frozen elephant trunk for total arch replacement in DeBakey type I dissection

OBJECTIVE

The study objective was to determine whether hybrid aortic repair yields superior outcomes compared with the conventional surgical approach for DeBakey type I aortic dissection.

METHODS

A retrospective analysis of patients with DeBakey type I dissection admitted to Fuwai Hospital between January 2010 and December 2016 showed that 815 patients (86.9%) underwent open total arch replacement with frozen elephant trunk (frozen elephant trunk group) and 122 (13.1%) underwent hybrid aortic arch repair without deep hypothermic circulatory arrest (hybrid group). We selected 109 pairs of patients for propensity score matching. Outcomes included early postoperative death, a composite of complications, dissected aorta remodeling, long-term survival, and freedom from reoperation.

RESULTS

Early mortality and complication rates were lower in the hybrid group, but the difference was not statistically significant (9.2% vs 17.4%, P = .073; 15.6% vs 25.7%, P = .066). The rates of postoperative renal insufficiency was significantly lower in the hybrid group than in the frozen elephant trunk group (22.9% vs 38.5%, P = .013); liver insufficiency and paraplegia were significantly lower in the hybrid group than in the frozen elephant trunk group (20.2% vs 33.9%, P = .022; 0% vs 6.4%, P = .014). After matched, the 1-year, 3-year, and 5-year survivals were 87.6%, 86.3%, and 82.2%, respectively, in the hybrid group and 80.7%, 76.5%, and 74.6% (P = .071), respectively, in the frozen elephant trunk group.

CONCLUSIONS

Hybrid aortic arch repair is a viable alternative treatment for patients with DeBakey type I aortic dissection, which improves outcomes and promotes remodeling of the dissected thoracic aorta.

[Method of forming a distal anastomosis with an autovenous cuff]

Presented herein is a brief review of the world literature dedicated to methods of formation of composite arterial anastomoses in the femoropopliteal-tibial region The most justified is considered the use of a composite shunt formed proximally from a synthetic vascular graft made of polytetrafluoroethylene and distally with an extension from a portion of the suitable for reconstruction autovein (the so-called autovenous cuff of patch). The use of an autovenous cuff is more physiological since it provides closer correspondence of the diameters of the distal anastomosis being applied between the artery and autovenous extension, as well as contributes to creation of more adequate haemodynamic conditions in the shunt. Also analysed is the technique of performing the previously suggested anastomoses, demonstrating their main disadvantages. This is followed by describing a new original method of formation of a distal anastomosis using an autovenous insert, showing its advantages, with the main amongst them being the presence of only two vascular sutures and a decrease in the possibility of the onset and development of turbulence in the zone of the anastomosis. A conclusion is drawn that the suggested method contributes to decreasing the duration of the main stage of the operation, decreases the probability of technical defects and reduces the risk for the development of postoperative complications associated with impairments of the processes of haemodynamics in the zone of the anastomosis formed.

[In situ aortofemoral reconstructions in surgical treatment of infected aortofemoral grafts]

The article presents a review of literature sources covering possibilities of peiforming in situ aortofemoral reconstructions in surgical treatment of infected aortofemoral grafts. This methodology makes it possible to improve the outcomes of treatment for paraprosthetic infection at the expense of decreasing lethality and morbidity, increasing parameters of patency of grafts and lower limb salvage in the remote postoperative period. Mention should be made that in situ secondary aortofemoral reconstructions are fraught with danger of relapsing paraprosthetic infection, therefore many publications are dedicated to search for prostheses most resistant to infection. The article also presents the results of works devoted to the use of various types of prostheses for in situ secondary aortofemoral reconstructions: prostheses made of polytetrafluoroethylene (PTFE), synthetic grafts saturated with various antibacterial drugs and gelatine, cadaveric allografts, synthetic prostheses treated with silver ions, autovenous conduits based on the femoral and popliteal veins.

[Efficiency of bioprosthesis in case of axillary-femoral bypass in patients with high operative risk]

It was analyzed the treatment results of 60 male patients with critical limb ischemia in case of atherosclerotic lesions of the aorta-iliac segment and severe somatic diseases. All patients were divided into 2 groups. Every group consisted 30 patients. The first group included axillary-femoral bypass by using of synthetic polytetrafluoroethylene prosthesis. The second group - by using of bioprosthesis of bull's internal thoracic arteries. Using of bioprosthesis allows to reduce early postoperative complications in intermediate postoperative period on 13.3%, late bypass thrombosis on 30%. Also there was elongation of average time of bypasses functioning in 1.8 times. Physical health was increased on 12.8%, mental - on 9.1%.

[Ways to improve patency of the femoral-popliteal-crural bypass grafts]

Chronic obliterating diseases of lower-limb arteries account for more than 20% of all manifestations of cardiovascular pathology. A surgical method of treatment for this pathology remains most effective. The types of operations below the inguinal fold currently used are as follows: bypass grafting, endarterectomy, and angioplasty. The vein is the material of choice and if it is not easily available allografts may be used. Differing elastic properties of the artery and prosthesis lead to progression of the neointima thus negatively affecting patency of bypass grafts. This article describes venous bypass grafts, their efficacy, methods of improving patency of allografts, as well as variants of combined operations.

[Restenosis of carotid arteries after carotid endarterectomy: current aspects of the problem: (local and systemic risk factors). Part 1]

Carotid endarterectomy is currently the most effective surgical means of preventing ischaemic stroke. Despite the fact that this type of intervention is widely used, there seems to be no tendency toward decreased incidence of such a complication as restenosis of carotid arteries.The present review deals with the results of analyzing the literature on the problem concerning carotid artery restenosis after carotid endarterectomy. Considered herein are the problems of epidemiology and prevalence of the complication involved. Special attention is paid to local and systemic risk factors for the development of restenosis. Studying risk factors of restenosis after carotid endarterectomy is of considerable importance for both prevention and choice of pathogenetically targeted treatment of patients presenting with atherosclerotic lesions of brachiocephalic vessels.

[Surgical treatment of leiomyosarcoma of the inferior vena cava]

The presented review of the literature is generalization of the currently existing data of foreign and Russian literature concerning treatment of a rare non-organic retroperitoneal tumour from smooth-muscle tissue, i. e., leiomyosarcoma of the inferior vena cava. The authors also formulate and lay down the basic principles of surgical interventions depending on the scope and level of the lesion, as well statistical analysis of the outcomes of surgical management of the this severely ill patient cohort.

[Aortic dissection type B with aortic arch involvement surgically treated--a case report]

A case of a 56-year-old male with acute aortic dissection type B is presented. The patient underwent successful surgery which was very difficult due to the extent of aortic dissection.

The Valiant thoracic endograft

Thoracic aortic pathology is common, but conventional surgery carries with it a significant risk of mortality and morbidity due to thoracotomy, extensive surgical dissection, partial left lung collapse, proximal aortic cross-clamping and blood loss necessary for open thoracic aortic replacement. Endovascular techniques have the potential to remove much of this harm. However, endograft delivery to the thoracic aorta brings its own challenges; the graft and delivery system must be conformable to follow the aortic arch, flexible to track through tortuous calcified vessels, of low profile for access through the iliac arteries, and deploy accurately and with minimal force to avoid accidental side branch occlusion. The endoprosthesis must also prove to be durable. This paper reviews current indications for thoracic aortic stent grafts and the properties of an ideal endograft for deployment in the arch and descending aorta. The Medtronic Valiant TM endoprosthesis with Xcelerant TM Delivery System is a third-generation system designed specifically for the treatment of a range of thoracic aortic pathologies, including but not exclusively, aneurysms and dissections. The design of the Valiant endoprosthesis and delivery system are described in detail, and compared to the second-generation Talent system. Our early experience of using Valiant in 28 patients with a range of pathologies is described. The graft achieved an initial technical success in 93% and was easy to position and deploy. Long-term data is now required; the Virtue Registry is a prospective multicenter European registry collecting clinical and health economics data on Valiant in the management of aortic dissections.

Use of Stent Grafts to Repair Hemodialysis Graft–related Pseudoaneurysms

PURPOSE

To review the author's early experience with stent grafts to repair hemodialysis graft-related pseudoaneurysms.

MATERIALS AND METHODS

Eleven patients had undergone insertion of a stent graft to repair a pseudoaneurysm arising from a PTFE hemodialysis graft. The study group consists of seven women and four men with a mean age of 50.7 years. The primary indications for stent graft placement were: rapid enlargement of a pseudoaneurysm in four patients, difficulty with cannulating the graft in two patients, high risk of acute rupture in three patients, persistent bleeding from the pseudoaneurysm in one patient, and one was incidentally discovered during diagnostic fistulography. In 10 of the 11 patients, the pseudoaneurysm arose from the arterial limb of a loop-configuration graft. A stent graft was successfully deployed in all patients. The radiological and surgical records were reviewed.

RESULTS

The Viabahn endoprosthesis was successfully inserted and deployed in all 11 patients. Six patients underwent subsequent interventions, which ended primary patency at 39 days, 40 days, 63 days, 104 days, 120 days, and 327 days after insertion of the stent graft. However, no additional interventions have been performed in five patients and primary patency continues. In these five patients the interval of continuing primary patency is 55 days, 92 days, 103 days, 139 days, and 196 days. In this small group of patients the primary patency rate is 71% at 3 months and 20% at 6 months.

DISCUSSION

Early experience has demonstrated that a stent graft can successfully exclude a pseudoaneurysm from a hemodialysis graft and may prevent further enlargement and decrease the likelihood of rupture. However, in two of these 11 patients, the large pseudoaneurysm remained problematic and required subsequent surgical repair.

Analysis of Prolapse in Cardiovascular Stents: A Constitutive Equation for Vascular Tissue and Finite-Element Modelling

The effectiveness of a cardiovascular stent depends on many factors, such as its ability to sustain the compression applied by the vessel wall, minimal longitudinal contraction when it is expanded, and its ability to flex when navigating tortuous blood vessels. The long-term reaction of the tissue to the stent is also device dependant; in particular some designs provoke in-stent restenosis (i.e., regrowth of the occlusion around the stent). The mechanism of restenosis is thought to involve injury or damage to the vessel wall due to the high stresses generated around the stent when it expands. Because of this, the deflection of the tissue between the struts of the stent (called prolapse or “draping”) has been used as a measure of the potential of a stent to cause restenosis. In this paper, uniaxial and biaxial experiments on human femoral artery and porcine aortic vascular tissue are used to develop a hyperelastic constitutive model of vascular tissue suitable for implementation in finite-element analysis. To analyze prolapse, four stent designs (BeStent 2, Medtronic AVE; NIROYAL, Boston Scientific; VELOCITY, Cordis; TETRA, Guidant) were expanded in vitro to determine their repeating-unit dimensions. This geometric data was used to generate a finite element model of the vascular tissue supported within a repeating-unit of the stent. Under a pressure of 450 mm Hg (representing the radial compression of the vessel wall), maximum radial deflection of 0.253 mm, 0.279 mm, 0.348 mm and 0.48 mm were calculated for each of the four stents. Stresses in the vascular wall were highest for the VELOCITY stent. The method is proposed as a way to compare stents relative to their potential for restenosis and as a basis for a biomechanical design of a stent repeating-unit that would minimize restenosis.

The FDA and regulatory issues in graft development

Regulatory issues in graft development range from mundane to complex because of the extensive diversity in graft technology. This article, describes the regulatory differentiation between types of grafts, incorporating a description of the system for classifying devices by the Food and Drug Administration (FDA). Information relating to the need for and the regulation of clinical investigations of grafts is included. This discussion includes a description of the current work by the International Organization of Standards on endovascular devices. Finally, a contrast between clinical studies sponsored by manufacturers and individual clinical investigators is provided.

The validity of canine platelet aggregometry in predicting vascular graft patency

Several laboratories have found canine platelet aggregometry predictive of thrombotic potential in vascular grafts. Adenosine diphosphate (ADP) is a frequently used agonist, often at unspecified or differing concentrations. This study was designed to evaluate the predictive value of ADP-induced platelet aggregometry and the validity of the methodology. Platelet aggregometry in response to 2 x 10(-5) M ADP was assayed in 70 dogs. Twenty-six percent were aggregators, 51% were non-aggregators, and 20% were indeterminant. All dogs were then treated with aspirin and dipyridamole. Vascular prostheses were implanted bilaterally (aorto-iliac) and anti-platelet therapy continued for two weeks. Dose-response to ADP was studied at three concentrations in 20 dogs. At 2 x 10(-5) 1/20 aggregated, at 4 x 10(-5) 3/19 aggregated and at 2 x 10(-4) 15/20 aggregated. Time between samples and study was evaluated in 11 dogs, with 2/11 changing from non-aggregator to aggregator at two or three hours. Daily reproducibility was studied in 70 dogs, 14 of which changed aggregation status between days. Patency was 58/68 (85%) for non-aggregators, 23/34 (68%) for aggregators (p = 0.038). Platelet aggregometry has significant predictive value for graft patency but methodology must be specified and standardized.

Iatrogenic vascular injury during peripheral revascularization

Iatrogenic vascular injury may occur during peripheral revascularization procedures secondary to the application of vascular occlusive devices. This review summarizes the known mechanical causes of such injury, relates this to clamp design, and suggests methods to minimize such injury by appropriate selection and handling of vascular occlusive clamps.