Long-term size follow-up of knitted Dacron grafts (Gelseal™) used in the ascending aorta

Biomaterials containing extracellular matrix molecules as biomimetic next-generation vascular grafts

The performance of synthetic biomaterial vascular grafts for the bypass of stenotic and dysfunctional blood vessels remains an intractable challenge in small-diameter applications. The functionalization of biomaterials with extracellular matrix (ECM) molecules is a promising approach because these molecules can regulate multiple biological processes in vascular tissues. In this review, we critically examine emerging approaches to ECM-containing vascular graft biomaterials and explore opportunities for future research and development toward clinical use.

Hemolytic anemia caused by kinked graft 6 months after aortic dissection repair

Background

Clinically insignificant hemolytic anemia is occasionally a complication of prosthetic valve replacement. However, hemolysis related to kinked grafts is a very rare complication after central repair for acute aortic dissection.

Case presentation

A 42-year-old man had undergone replacement of the ascending aorta and a root repair for type A aortic dissection 6 months previously. Laboratory data showed mild hemolysis 5 months later, and he began to complain of fatigue on exertion. The serum hemoglobin level reduced to 8.6 g/dL, and lactate dehydrogenase levels increased to 3071 IU/L with gross change in urine color, indicating hemoglobinuria. We diagnosed mechanical hemolytic anemia caused by a kinked graft and planned a repeat operation. The kinked graft was resected and graft-graft anastomosis was performed. Postoperatively, the clinical course was uneventful, and the hemolytic anemia completely resolved.

Conclusion

We herein report a case of hemolytic anemia caused by kinking of the graft 6 months after acute aortic dissection repair. The diagnosis was swiftly made, and the patient was successfully managed with redo surgery.

TEVAR and EVAR, the unknown knowns of the cardiovascular hemodynamics; and the immediate and long-term consequences of fabric material on major adverse clinical outcome

This review discusses the impact of endovascular aneurysm repair on cardiovascular (CV) hemodynamics and the role of stent-graft material, i.e., polytetrafluoroethylene (PTFE) vs. polyester in post-procedural outcomes. Endovascular aneurysm repair has been widely employed in the last decades for thoracic and abdominal aneurysm repair. However, aortic endografts are stiff and alter the native flow hemodynamics. This failure to simulate the native aorta could lead to added strain on the heart, manifesting as increased left ventricular strain, higher pulse pressure, and congestive heart failure later. This could result in adverse CV outcomes. Also, evidence is mounting to support the implication of stent-graft materials, i.e., PTFE vs. polyester, in adverse post-procedural outcomes. However, there is an absence of level one evidence. Therefore, the only way forward is to plan and perform a randomised controlled trial to demonstrate the alterations in the CV hemodynamics in the short and long run and compare the available stent-graft materials regarding procedural and clinical outcomes. We believe the best solution, for now, would be to reduce the stented length of the aorta. At the same time, in the longer term, encourage continuous improvement in stent-graft materials and design.

Model-Based Fluid-Structure Interaction Approach for Evaluation of Thoracic Endovascular Aortic Repair Endograft Length in Type B Aortic Dissection

Thoracic endovascular aortic repair (TEVAR) is a commonly performed operation for patients with type B aortic dissection (TBAD). The goal of TEVAR is to cover the proximal entry tear between the true lumen (TL) and the false lumen (FL) with an endograft to induce FL thrombosis, allow for aortic healing, and decrease the risk of aortic aneurysm and rupture. While TEVAR has shown promising outcomes, it can also result in devastating complications including stroke, spinal cord ischemia resulting in paralysis, as well as long-term heart failure, so treatment remains controversial. Similarly, the biomechanical impact of aortic endograft implantation and the hemodynamic impact of endograft design parameters such as length are not well-understood. In this study, a fluid-structure interaction (FSI) computational fluid dynamics (CFD) approach was used based on the immersed boundary and Lattice–Boltzmann method to investigate the association between the endograft length and hemodynamic variables inside the TL and FL. The physiological accuracy of the model was evaluated by comparing simulation results with the true pressure waveform measurements taken during a live TEVAR operation for TBAD. The results demonstrate a non-linear trend towards increased FL flow reversal as the endograft length increases but also increased left ventricular pulsatile workload. These findings suggest a medium-length endograft may be optimal by achieving FL flow reversal and thus FL thrombosis, while minimizing the extra load on the left ventricle. These results also verify that a reduction in heart rate with medical therapy contributes favorably to FL flow reversal.

Combined thoracic endovascular aortic repair and endovascular aneurysm repair and the long-term consequences of altered cardiovascular haemodynamics on morbidity and mortality: case series and literature review

Background

Thoracic and abdominal aortic stent grafts are firmer and more rigid than the native aorta. Aortic implanted devices have been implicated in the development of acute systolic hypertension, elevated pulse pressure, and reduced coronary perfusion.

Case summary

We report four cases of staged thoracic endovascular aortic repair (TEVAR) and then endovascular aneurysm repair (EVAR). All patients had TEVAR first for thoracic aortic aneurysm and later on developed infra-renal abdominal aortic aneurysm (AAA) that required EVAR. There were three males and one female with a median age of 74.5 years (range 67.5-78.5). None of the patients developed aortic-related major clinical adverse effects or required any aortic intervention during their follow-up. However, within 2 years, all patients developed symptomatic left ventricular hypertrophy with diastolic dysfunction. All patients had bilateral lower limb oedema, with on and off chest pain and shortness of breath (SOB), necessitating coronary angiograms, which showed no evidence of coronary artery disease. Three patients died from cardiovascular-related morbidities, and the fourth patient is still complaining of SOB despite a normal coronary angiogram.

Discussion

Aortic-endograft compliance mismatch is an invisible enemy, with troubling consequences for the aorta proximal and distal to the endograft. Aortic stiffness due to vascular endograft could lead to cardiovascular adverse events, even in the absence of direct aortic-related complications. After combined TEVAR and EVAR, the compliance mismatch and elasticity loss are even more pronounced than with TEVAR alone, which necessitates patient monitoring for the development of cardiovascular complications.

Graft Dilatation May Cause Secondary Regurgitation in Aortic Valve-Sparing Operations

Aortic valve-sparing operations are meant to stabilize the root in order to provide stable aortic valve function. The possibility of graft dilatation has been known in other forms of aortic replacement but is largely ignored in valve-preserving surgery. We describe graft dilatation as a cause of failure late after aortic valve reimplantation. It was corrected by applying the concepts of aortic valve repair.

Prosthetic Graft Dilation at the Aortic Arch in the Era of Hybrid Aortic Surgery

Objective: This study aims to evaluate the chronological size changes of the prosthetic graft in the aortic arch, which is used as a landing zone for a subsequent stent grafting in hybrid aortic surgery.

Materials and Methods: Eighty-five patients who underwent total aortic arch replacement followed by computed tomography follow-up for at least 30 months after the surgery were included in the study.

Results: Prosthetic grafts used were Hemashield (Maquet, Rastatt, Germany), J-Graft (Japan Lifeline Inc., Tokyo, Japan) and Triplex (Terumo, Tokyo, Japan). There was an initial increase in diameter compared to package size after implantation (Hemashield, 1.04±0.035 vs. J-Graft, 1.06±0.027 vs. Triplex, 1.04±0.023, p=0.13). Significant difference in graft dilation ratio was observed in Triplex (1.18±0.062) at long-term compared to Hemashield (1.07±0.052, p<0.001) and J-Graft (1.10±0.071, p<0.001). Multivariate analysis showed that age (r=0.002; 95% confidence interval [CI], 0.0001–0.0037; p=0.035), knitted-type prosthesis (r=0.089; 95% CI, 0.0610–0.1163; p<0.0001), and prevalence of cerebral vascular disease (r=0.038; 95% CI, 0.0030–0.0732; p=0.034) were independently associated with graft dilation after surgery.

Conclusion: Prosthetic graft selection and appropriate sizing of the stent graft should be considered for each individual undergoing hybrid aortic surgery to maintain sufficient oversizing of the stent graft.

Old Myths, New Concerns: the Long-Term Effects of Ascending Aorta Replacement with Dacron Grafts. Not All That Glitters Is Gold

Synthetic grafts are widely used in cardiac and vascular surgery since the mid-1970s. Despite their general good performance, inability of mimicking the elastomechanical characteristics of the native arterial tissue, and the consequent lack of adequate compliance, leads to a cascade of hemodynamic and biological alterations deeply affecting cardiovascular homeostasis. Those concerns have been reconsidered in more contemporaneous surgical and experimental reports which also triggered some research efforts in the tissue engineering field towards the realization of biomimetic arterial surrogates. The present review focuses on the significance of the “compliance mismatch” phenomenon occurring after aortic root or ascending aorta replacement with prosthetic grafts and discusses the clinical reflexes of this state of tissue incompatibility, as the loss of the native elastomechanical properties of the aorta can translate into detrimental effects on the normal efficiency of the aortic root complex with impact in the long-term results of patients undergoing aortic replacement.

Pseudoaneurysm of graft-graft anastomosis of a hand-sewn branched graft: a case report

Background

Pseudoaneurysm of graft–graft anastomosis is an extremely rare but potentially fatal complication after thoracic aorta replacement with a prosthetic graft. We report a case of pseudoaneurysm at the graft–graft anastomosis of a hand-sewn branched graft.

Case Presentation

A 65-year-old man underwent total arch replacement with a hand-sewn branched graft for Stanford type A acute aortic dissection 22 years ago. During follow-up, serial CT scans showed a pseudoaneurysm on the branched graft which warranted reintervention. Surgical repair involved direct suture of multiple bleeding points which were found at the sites of the hand-sewn branches anastomosis. The postoperative course was uneventful, and no signs of bleeding were observed by CT after the reoperation.

Conclusions

Long-term follow-up is essential to detect late complications at the site of hand-sewn anastomosis.

Systematic review of interventions to repair ascending aortic pseudoaneurysms

BACKGROUND

The safety and efficacy of endovascular therapies for ascending aortic pseudoaneurysms (AAPs) are still controversial.

METHODS

We report an endovascular correction of an AAP in a high-risk surgical patient and present the results of a literature review focusing on AAP treatment strategies. A multilingual search of AAP therapy was performed with limiting dates of January 1980 to May 2014. The studies were classified by intervention.

RESULTS

A 79-year-old male with a 9 × 10 × 7 cm AAP in the anterior mediastinum was considered too high risk for surgery. An endovascular closure with a 12 mm Amplatzer septal occluder device (St. Jude Medical) was performed, and computed tomography angiography at 3-month follow-up exhibited a thrombosed AAP with minimal residual shunt. In our literature search, we identified 355 cases of AAPs, mostly case reports (91.5%) and a few patient series (8.5%). Surgical correction accounted for 73.8% of the cases, 5% of the patients were conservatively treated or considered too critically ill for any intervention, and 21.2% were treated with endovascular techniques. The most commonly reported endovascular techniques were stent grafts (9.8%) and septal occluder devices (9.8%).

CONCLUSION

Although endovascular closure of AAPs with off-label devices is a reliable option for controlling the expansion and symptoms in high-risk surgical patients, solid data on survival are lacking. Efforts to promote discussion within the heart team to expand the application of endovascular techniques can provide groundbreaking evidence to support the use of endovascular techniques as guideline therapy when facing these complicated cases.

Thoracic endovascular aortic repair in patients with prior open aortic surgery

OBJECTIVE

To review our experience of thoracic endovascular aortic repair (TEVAR) in patients with prior open aortic repair (OAR).

MATERIALS AND METHODS

Stent-grafts were deployed in the arch, descending thoracic and thoracoabdominal aortae of 39, 13 and 5 patients, respectively, and in a deteriorated extra-anatomical prosthesis in one. The access route was the femoral artery in 10 of 23 patients with, and in 30 of 35 patients without a prior abdominal prosthesis. Prior prostheses and elephant trunks comprised 57 of 116 landing zones and 23 proximal landing zones, respectively.

RESULTS

Three patients died before discharge. Type II endoleaks developed in six patients, and Types I and III developed in one patient each. Type I endoleaks were not found at landing zones comprising prosthetic grafts. The overall actuarial three-year survival rate including early mortality was 86.5%.

CONCLUSION

The clinical outcomes of TEVAR were excellent, even in patients with prior OAR. Prosthetic grafts, including elephant trunks, provided good landing zones for TEVAR. Prostheses with larger-caliber designs are recommended for iliac artery reconstruction in future TEVAR.