State of the Art Review: Surgical Treatment of Acute Type A Aortic Dissection.

Acute type A aortic dissection (ATAAD) is a life-threatening event that requires immediate surgical treatment. Improvements in surgical treatment, graft technology, organ protection and imaging techniques have led to improved clinical outcomes. Individualized treatment concepts have emerged based on more advanced planning tools that allow for a tailored approach even in complex situations such as multi-level malperfusion. This review provides an overview of the current surgical treatment of ATAAD, focusing on new disease classifications, preoperative computed tomography angiography (CTA) assessment, new prosthesis and stent technologies, and organ-protection strategies.

Endovascular treatment of an anastomotic outflow graft pseudoaneurysm of the descending aorta after implantation of a left ventricular assist device.

INTRODUCTION: Outflow graft (OG) obstruction is a dangerous complication that may occur for various reasons after the implantation of the left ventricular assist device (LVAD). CASE REPORT: In this study, we describe the case of a 67-year-old patient on LVAD support who developed a late pseudoaneurysm of the OG anastomosis (to the descending aorta) causing OG stenosis at the level of the anastomosis. The patient was treated with a customized fenestrated endovascular stent graft placed into the descending aorta and stent implantation into the OG.

New Hybrid Prosthesis for Acute Type A Aortic Dissection.

BACKGROUND: Acute type A aortic dissection (ATAAD) is a surgical emergency with high rates of morbidity and mortality. The treatment of ATAAD is highly individualized and mainly depends on anatomical and technical factors. Great efforts to reduce the time to diagnosis and technological innovations have led to improved surgical results with a lower rate of dissection-related reoperations during long-term follow up. The aim of this article is to introduce a novel hybrid device for the treatment of DeBakey I acute aortic dissection. CONCEPT: A non-covered hybrid stent from Ascyrus Medical (Boca Raton, FL, USA) aims to improve the current standard of care, without increasing technical complexity or device-related complications. The AMDS (Ascyrus Medical Dissection Stent) prolongs the hemiarch operation by only a few minutes, does not need endovascular skills to be deployed, and provides an anatomical and "haemodynamic" correction. The device is intended to reduce perfusion of the false lumen by sealing the distal anastomosis, and to restore distal perfusion of the true lumen. Obliteration of the false lumen at the distal anastomosis is likely to reduce aortic enlargement and the need for reoperations, mainly driven by a low-flow state and pressure reduction, which promote thrombosis. CONCLUSIONS: The AMDS provides a new concept to treat acute aortic dissection by moving the focus from resecting the dissected tissue to restoring adequate true-lumen flow and sealing the false lumen at the distal anastomosis. With a high rate of procedural success, AMDS represents a safe, reproducible and promising solution to treat DeBakey I aortic dissections.

Prospective Study of the Iliac Branch Device E-liac in Patients with Common Iliac Artery Aneurysms: 12 Month Results.

OBJECTIVES: At 12 months follow up of the PLIANT study, clinical success and efficacy of the E-liac Stent Graft System (JOTEC GmbH, Hechingen, Germany) were evaluated. Clinical success was defined as aneurysm exclusion (no type I, III, IV endoleak) with primary patency of the internal iliac artery (IIA) and external iliac artery (EIA) on the E-liac implantation side. METHODS: In this prospective multicentre European observational study, clinical and morphological data of 45 patients (93% male, mean age 72 y) were prospectively collected in 11 European centres between July 2014 and June 2016. Forty patients underwent an aorto-iliac (three patients bilaterally) treatment and five an isolated iliac treatment. RESULTS: At 12 months follow up, data were available for 42 patients. Overall clinical success at 12 months was 90%, with a survival rate of 100%. Four patients (10%) did not achieve clinical success, one with an internal iliac artery (IIA) occlusion on the E-liac implantation side, one with an infrarenal type Ia endoleak, and two with type Ib endoleaks in IIA. At 12 months the primary patency rate in the internal iliac artery on the iliac side branch implantation side was 98%. Two patients (5%) received E-liac related re-interventions: one caused by an edge stenosis at the distal end of the graft limb in the external iliac artery (EIA) and one caused by thrombo-embolism in the external iliac artery. Thus, for the EIA, primary and secondary patency rates were 98% and 100%, respectively. CONCLUSIONS: The low device related re-intervention rate of 5%, the high survival rate of 100%, and the high primary patency rates of 98% for the IIA and EIA at 12 month follow up demonstrate the safety and efficacy of the E-liac Stent Graft System. Long term 36 month results are awaited to confirm the efficacy and durability.

Transcatheter Valve-in-Valve and Valve-in-Ring Interventions for Failing Bioprostheses and Annuloplasty Rings.

Transcatheter aortic valve implantation has dramatically changed the treatment of valvular heart disease over the past decade. At the same time, the indications for bioprosthesis implantation have been continuously extended toward younger patients, driven by excellent clinical results and improved durability. While the omission of oral anticoagulation reduces the risk of severe bleeding complications, the long-term durability of bioprostheses is still limited. In light of the growing number of elderly transcatheter aortic valve replacement (TAVR) patients, the prevalence of patients with failed bioprostheses and advanced comorbidities is expected to rise. Currently, transcatheter valve-in-valve (ViV) and valve-in-ring (ViR) interventions represent a valuable alternative treatment option for patients with a high risk for surgical reoperation. Several reports have described a high procedural success rate and low postprocedural morbidity and mortality during mid-term follow-up. We are still facing valve-specific and procedure-related challenges in all types of procedures, but especially in transcatheter ViR interventions. Considering the high technical demand of these interventions, a strong and highly specialized heart team in heart valve centers is the cornerstone of successful patient treatment. This review focuses on individualized patient selection, procedure-specific risk factors and technical aspects of transcatheter ViV/R interventions, and explores the currently available literature on postinterventional outcome.

Prospective study of the E-liac Stent Graft System in patients with common iliac artery aneurysms: 30-Day results.

OBJECTIVES: To study the safety and feasibility of the E-liac Stent Graft System® in patients with aorto/iliac aneurysms. METHODS: A prospective multicentric European registry of patients receiving the E-liac Stent Graft System® was conducted. Endpoints of the study included the technical success as well as periprocedural events and 30-day endoleaks, reinterventions, internal and external iliac artery patency and mortality. RESULTS: Between July 2014 and June 2016, a total of 45 patients (93% men, mean age 72 years, range 53-90 years) were enrolled at 11 sites in four European countries. Five patients received an isolated iliac treatment. Thirty-seven patients were treated with a combination of an abdominal stent graft and a unilateral E-liac and three in combination with bilateral E-liac. All E-liac Stent Grafts (48) were implanted in the intended position and the internal iliac arteries were successfully bridged. Two patients did not receive clinical success, due to endoleak type Ia of the aortic stent graft. At 30-day follow-up, clinical success rate was 96%. Three successful endovascular reinterventions were performed within the 30-day follow-up: one due to a type Ia endoleak in the common iliac artery, one due to type Ia endoleak of the aortic stent graft, and one due to bilateral lower limb claudication provoked by stent graft limb stenosis. At 30-day, a 100% survival rate and complete absence of pelvic or buttock ischemia/claudication were reported. Primary patency at 30 days was 100% for the internal iliac artery and 98% for the external iliac artery with an assisted patency of 100% in the latter. CONCLUSIONS: The high clinical success rate, low rates of device-related reinterventions (2%), and excellent patency rate demonstrate the safety and feasibility of the E-liac Stent Graft System. Long-term results are awaited to state efficacy and durability. Clinical Trials.gov. Identifier no. NCT02209194.

The Ascyrus Medical Dissection Stent: A One-Fits-All Strategy for the Treatment of Acute Type A Aortic Dissection?

The treatment of DeBakey type I aortic dissection remains a major challenge in the field of aortic surgery. To upgrade the standard of care hemiarch replacement, a novel device called an "Ascyrus Medical Dissection Stent" (AMDS) is now available. This hybrid device composed of a proximal polytetrafluoroethylene cuff and a distal non-covered nitinol stent is inserted into the aortic arch and the descending thoracic aorta during hypothermic circulatory arrest in addition to hemiarch replacement. Due to its specific design, it may result in a reduced risk for distal anastomotic new entries, the effective restoration of branch vessel malperfusion and positive aortic remodeling. In this narrative review, we provide an overview about the indications and the technical use of the AMDS. Additionally, we summarize the current available literature and discuss potential pitfalls in the application of the AMDS regarding device failure and aortic re-intervention.

Mediastinal transposition of the greater omentum for treatment of infected prostheses of the ascending aorta and aortic arch.

OBJECTIVES: The aim of this study was to evaluate the outcomes of transposition of the omentum into the mediastinum to support the replacement of infected aortic grafts or to cover infected aortic grafts that are not amenable for surgical replacement. METHODS: All patients with thoracic aortic graft infections who underwent mediastinal transposition of the omentum at our institution between 2005 and 2023 were included in this study. Mediastinal transposition of the omentum was performed either after replacement of the infected graft ('curative concept') or solely as bailout procedure by wrapping the infected graft ('palliative concept'). The diagnosis, including computed tomography scans during follow-up, was made according to the criteria of the Management of Aortic Graft Infection Collaboration. RESULTS: The patient cohort consisted of 31 patients. Both in-hospital and 1-year mortality were 0% (n = 0) for the curative concept (n = 9) compared to 23% (n = 5) and 41% (n = 9) for the palliative concept (n = 22), respectively. There was no graft infection-associated death or recurrence of infection after 3 years in the curative group. Survival was 52% at 3 years in the palliative group, with freedom of infection in 59% of the patients (n = 13). CONCLUSIONS: Transposition of the omentum and wrapping of the infected aortic prosthetic graft is a useful bailout strategy for patients who are ineligible for replacement of an infected aortic graft. However, mortality stays high. For radical treatment of aortic graft infections, it may prove an effective supportive therapy and represents an important tool in the armamentarium of cardiac surgeons.

Outcomes and survival following thoracic endovascular repair in patients with aortic aneurysms limited to the descending thoracic aorta.

BACKGROUND: Thoracic endovascular aortic repair (TEVAR) is a well-established therapy for descending aortic aneurysms (DTA). There is a paucity of large series reporting the mid- and long-term outcomes from this era. The main aim of this study was to evaluate the outcomes of TEVAR with regards to the effect of aortic morphology and procedure-related variables on survival, reintervention and freedom from endoleaks. METHODS: In this retrospective single center study, we evaluated the clinical outcomes among 158 consecutive patients with DTA than underwent TEVAR between 2006 and 2019 at our center. The cohort included 51% patients with device landing zones proximal to the subclavian artery and 25.9% patients undergoing an emergent or urgent TEVAR. The primary outcome was survival, and secondary outcomes were reintervention and occurrence of endoleaks. RESULTS: Median follow-up was 33 months [IQR 12 to 70] while 50 patients (30.6%) had longer than 5-year follow-up. With a median patient age of 74 years, post-operative Kaplan Meyer survival estimates were 94.3% (95%CI 90.8-98.0, SE 0.018%) at 30 days, 76.4% (95%CI 70.0-83.3, SE 0.034%) at one year and, 52.9% (95%CI 45.0-62.2, SE 0.043%) at five years. Freedom from reintervention at 30 days, one year, and five years was 92.9% (95%CI 89.0-97.1, SE 0.021%), 80.0% (95%CI 72.6-88.1, SE 0.039%), and 52.8% (95%CI 41.4-67.4, SE 0.065%), respectively. On cox regression analysis greater aneurysm diameter, and the use of device landing zones in aortic regions 0-1 were associated with an increased probability of all-cause mortality, and with reintervention during follow-up. Independent of aneurysm size undergoing urgent or emergent TEVAR was associated with higher mortality risk for the first three years post-operative but not on long-term follow-up. CONCLUSIONS: Larger aneurysms and those requiring stent-graft landing in aortic zones 0 or 1, are associated with higher risk for mortality and reintervention. There remains a need to optimize clinical management and device design for larger proximal aneurysms.

Case Report: Successful endovascular treatment of acute type A aortic dissection.

Introduction: Open surgical repair remains the current gold standard for the treatment of acute type A aortic dissection. However, especially elderly patients with relevant comorbidities who are deemed unfit for open surgery may benefit from a minimally invasive endovascular approach. Methods: We report a case of an 80-year-old male with retrograde acute type A aortic dissection and peripheral malperfusion after receiving thoracic endovascular aortic repair due to thoracic aortic aneurysm. Our individualized endovascular approach consisted of left carotid-subclavian bypass, proximal extension of thoracic endovascular aortic repair using a covered stent graft and a single covered stent graft for the ascending aorta in combination with an uncovered stent for the aortic arch. Results: Postoperative computed tomographic angiography demonstrated excellent outcome with no signs of endoleak or patent false lumen. Follow-up after 3.5 years showed a stable result with no signs of stent failure or dissection progress. No aortic re-interventions were needed in the further course. Discussion: An individualized endovascular approach may be justified for acute type A aortic dissection in elderly patients with high surgical risk if performed in specialized aortic centers. Additional short-length stent graft devices are needed to address the anatomical challenges of the ascending aorta. For enhanced remodeling of the dissected aorta, the use of an additional uncovered stent may be advisable.

Cerebral Protection Strategies and Stroke in Surgery for Acute Type A Aortic Dissection.

BACKGROUND: Perioperative stroke remains a devastating complication in the operative treatment of acute type A aortic dissection. To reduce the risk of perioperative stroke, different perfusion techniques can be applied. A consensus on the preferred cerebral protection strategy does not exist. METHODS: To provide an overview about the different cerebral protection strategies, literature research on Medline/PubMed was performed. All available original articles reporting on cerebral protection in surgery for acute type A aortic dissection and neurologic outcomes since 2010 were included. RESULTS: Antegrade and retrograde cerebral perfusion may provide similar neurological outcomes while outperforming deep hypothermic circulatory arrest. The choice of arterial cannulation site and chosen level of hypothermia are influencing factors for perioperative stroke. CONCLUSIONS: Deep hypothermic circulatory arrest is not recommended as the sole cerebral protection technique. Antegrade and retrograde cerebral perfusion are today's standard to provide cerebral protection during aortic surgery. Bilateral antegrade cerebral perfusion potentially leads to superior outcomes during prolonged circulatory arrest times between 30 and 50 min. Arterial cannulation sites with antegrade perfusion (axillary, central or carotid artery) in combination with moderate hypothermia seem to be advantageous. Every concept should be complemented by adequate intraoperative neuromonitoring.

The impact of malperfusion patterns in elderly patients undergoing surgery for acute type A aortic dissection.

OBJECTIVES: The aim of this study is to investigate the outcome of elderly patients with surgically treated acute type A aortic dissection (ATAAD) complicated by malperfusion. METHODS: Patients ≥70 years old who underwent surgical treatment for ATAAD between January 2000 and December 2020 were enrolled in this study and stratified by their specific Penn Classification into 4 different subgroups, where Penn Abc was defined as multilevel malperfusion. Short- and long-term outcomes were investigated. Multivariable binary logistic regression was performed to identify risk factors for 1-year mortality. RESULTS: Four hundred elderly patients underwent surgical treatment for ATAAD. A total of 204 (51%) patients had no evidence of malperfusion (Penn Aa), 106 (26.5%) had localized organic malperfusion (Penn Ab), 44 (11%) patients had systemic malperfusion (Penn Ac) and 46 (11.5%) suffered from multilevel malperfusion (Penn Abc). For the latter, in-hospital mortality was 70% (P < 0.001). Age (P < 0.006) and multilevel malperfusion (P < 0.001) were independent risk factors for 1-year mortality. Patients with multilevel malperfusion showed the worst 1-year survival (P < 0.001). In the case of Penn Aa, in-hospital mortality was 13% (P < 0.001). CONCLUSIONS: Surgery may lead to satisfactory results in the absence of malperfusion, even in octogenarians. Elderly patients with multilevel malperfusion show very poor surgical outcome. In these patients, the decision for surgery should be taken with caution. Operation, if performed, should be carried out by experienced teams only.

Transcatheter aortic valve implantation into a stentless prosthetic valve with a low position of the left main coronary artery.

Recently during a transcatheter aortic valve implantation (TAVI), we were faced with a problem that seemed to be untreatable by TAVI. It was difficult to decide whether to perform atypical TAVI or to convert to conventional redo aortic valve surgery in an extremely high-risk patient with a degenerated stentless aortic bioprosthesis.

Rescue transcatheter aortic valve implantation and simultaneous percutaneous coronary intervention on cardiopulmonary bypass in a patient with an extreme risk profile.

We report on successful emergency transcatheter aortic valve implantation combined with percutaneous coronary revascularization in a polymorbid and preterminal patient in profound cardiogenic shock and with multiorgan failure. The risk scores were almost unbelievably high (Society of Thoracic Surgeons mortality score, 83.9%; Society of Thoracic Surgeons morbidity and mortality score, 96.8%; logistic EuroSCORE, 96.7%). Two and a half years after the procedure, the patient is doing very well.

Matched comparison of 3 cerebral perfusion strategies in open zone-0 anastomosis for acute type A aortic dissection.

OBJECTIVES: The present study aims to investigate outcomes after the surgical treatment of acute type A aortic dissection in regard to three available selective cerebral perfusion strategies. METHODS: From 2000 to 2019, patients were selected based on the employment of either retrograde cerebral perfusion (RCP), unilateral antegrade cerebral perfusion (uACP) or bilateral antegrade cerebral perfusion (bACP) during open zone-0 anastomosis. Propensity score TriMatch analysis considering several preoperative and intraoperative variables was used to identify well-balanced triplets. The primary end point of the study was a new cerebral operation-related neurologic deficit. RESULTS: Operative times (operation time, cardiopulmonary bypass time, reperfusion time) were significantly longer in the RCP group, in which deeper hypothermia was applied (27.5 [24-28], 28 [26-28] and 16 [16-17]°C for uACP, bACP and RCP, respectively, P-value <0.001). The RCP group showed higher red blood cell concentrates and fresh frozen plasma transfusion rates. No significant difference of new cerebral operation-related neurologic deficit was observed between the 3 groups (12.9% vs 12.9% vs 11.3% for RCP, uACP and bACP, P-value = 0.86). In addition, 30-day mortality showed similar distribution independently of the cerebral perfusion strategy adopted (17.7% vs 14.5% vs 17.7% for RCP, uACP and bACP, P-value = 0.86). CONCLUSIONS: However, based on a small sample size, the comparison showed no relevant differences in terms of neurologic outcome and 30-day mortality, confirming RCP, uACP and bACP as safe and reproducible selective cerebral perfusion strategies in surgery for acute type A aortic dissection.

Revascularization of Left Subclavian to Common Carotid Artery Prepares for Covered Stent Implantation in Patients With Complex Aortic Coarctation.

Seven adult patients underwent a two-stage treatment of complex coarctation (CoA), including surgical revascularization of the left subclavian artery (LSA) to left common carotid artery (LCCA), followed by transcatheter covered stent implantation. The majority of patients (5 of 7, 71%) received 1 covered stent (covered Cheatham Platinum stent: 8 zig/45 mm [n = 2], 10 zig/60 mm [n = 1], 10 zig/65 mm [n = 1]; BeGraft: 24/48 mm [n = 2]). In 1 patient (14%), the implantation of 2 covered stents (BeGraft 20/48 mm) was necessary. During a median follow-up of 2.4 years (interquartile range, 0.1 to 4.9 years), complications occurred in 3 of 7 patients (43%), including an asymptomatic but severe stenosis of the LSA bypass (n = 1), a recoarctation with a mild endoleak (n = 1), and a severe endoleak (n = 1). Surgical revascularization of the LSA to the LCCA can successfully prepare for covered stent implantation in complex CoA in adult patients. This two-stage approach was feasible and safe with complications occurring in 3 of 7 patients (43%). All complications were managed by catheter reintervention only.

Aortic remodelling and late outcomes following thoracic endovascular repair with a bare-metal stent distal extension among patients with complicated type-B aortic dissection.

OBJECTIVES: The goal of this study was to describe the factors affecting mid and late aortic remodelling following thoracic endovascular aortic repair with the PETTICOAT (Provisional Extension To Induce Complete Attachment) technique among patients with complicated acute or subacute type B aortic dissection. METHODS: A retrospective single-centre study that evaluates clinical and morphological outcomes among 65 consecutive patients. The area and diameter of the true and false lumen, overall aortic diameter and false lumen perfusion were evaluated. RESULTS: Concomitant direct visceral artery stenting was successfully conducted in 32 (49%) patients. There was one (1.5%) postoperative stroke; three (4.6%) patients developed spinal cord ischaemia; two (3%) patients suffered retrograde type A dissection; and two (3%) patients had mesenteric ischaemia, despite successful reperfusion, that required a bowel resection. Median postoperative follow-up was 63.1 (interquartile range, 32.1- 91.8) months. The probability of survival was 96.9% [95% confidence interval (CI) 88.3%-99.2%] at 30 days, 93.9% (95% CI 84.4%-97.6%) at 1 year, 78.0 (95% CI 64.2%-87.0%) at 5 years and 72.8% (95% CI at 57.9%-83.2%) at 10 years postoperatively. There was a statistically significant postoperative increase in true-lumen area, diameter and true-lumen index in all five aortic levels measured. Complete false lumen (FL) thrombosis at the coeliac trunk, renal arteries and aortic bifurcation levels was observed in 47%, 15% and 24% of patients at midterm (6-15 months) and in 29%, 21% and 29% on late (later than 21 months) computed tomography angiograms (CTA). Persistent false lumen (FL) perfusion at the coeliac level on midterm CTA was associated with a larger extent of late aortic growth (P = 0.042) and was, in the majority of cases, caused by iliac re-entries either alone (28.57) or in combination with visceral and lumbar (28.57%) or distal aortic (10.71%) re-entries. A larger abdominal aortic diameter at midterm was associated with an increased probability of distal aortic reinterventions (hazard ratio 7.26, 95% CI 2.41-21.9, P < 0.001). CONCLUSIONS: Persistent FL perfusion of the distal aorta at midterm following TEVAR with the PETTICOAT technique among patients with acute and subacute type B dissection is caused mainly by iliac, visceral, lumber and distal aorta re-entries. Patients with persistent FL perfusion have an increased risk of aortic aneurysmal growth at late follow-up.

Transapical aortic valve implantation and 'off-pump' arterial coronary bypass in a patient with a porcelain aorta.

A simple hybrid procedure, namely transapical aortic valve implantation combined with 'off-pump' coronary artery bypass using an internal thoracic artery, was performed in a patient with porcelain aorta, aortic valve stenosis and coronary artery disease. This approach does not require cardiopulmonary bypass, and avoids aortic or peripheral arterial cannulation and clamping of the aorta. This hybrid approach can be regarded as a 'new technique' being applied to an 'old idea'.

Transcatheter aortic valve implantation and simultaneous closure of ostium secundum atrial septal defect.

We were faced with a difficult question: how to treat a high-risk patient with severe aortic valve stenosis and a secundum atrial septal defect (ASD II). An 85-year-old woman with progressive dyspnea and pedal edema and in New York Heart Association class IV was treated with concomitant transapical aortic valve implantation and transcatheter closure of the ASD II. The combined procedure and postoperative course were completely uneventful. At 2 years after the clinical follow-up, the patient is doing well. This case report demonstrates, for the first time, the feasibility, safety, and effectiveness of simultaneous application of 2 transcatheter methods--aortic valve implantation and closure of an ASD II. As surgeons, we should consider percutaneous treatment of combined structural heart disease in patients at high risk for conventional surgery.

Initial experience with the new type A arch dissection stent: restoration of supra-aortic vessel perfusion.

OBJECTIVES: The goal of the present study is to investigate changes in supra-aortic vessel perfusion after implantation of the non-covered Ascyrus Medical Dissection Stent (AMDS) for surgical treatment of acute type A aortic dissection. METHODS: From 2017 to 2020, 16 consecutive patients treated with AMDS and involvement (dissection to total occlusion) of at least 1 supra-aortic vessel were included in the study. Centre-line based computed tomography measurements of true, false and total lumen area using Terarecon software were performed before and after surgery. Changes in the true lumen area were indexed to the entire vessel area. The paired sample t-test was used to assess the significance of the observed differences. RESULTS: Analysis of supra-aortic vessels and the descending aorta showed significant improvement in true lumen perfusion after the AMDS was implanted. The indexed true lumen area increased postoperatively by 72%, 112% and 30% in the innominate, right and left common carotid arteries, respectively. Total occlusions of both common carotid arteries recovered completely after surgical treatment. The proximal- and the mid-descending aorta showed a 78% and 48% improvement of the indexed true lumen area, respectively. CONCLUSIONS: Arch repair using AMDS shows promising results in the treatment of acute type A aortic dissection. Quantitative measurements of true and false lumen perfusion demonstrated a significant increase in true lumen area and a 100% regression of totally occluded supra-aortic branches. Further examination in a larger cohort of patients and comparison with isolated hemiarch repair are needed to confirm positive vascular remodelling after an AMDS implant.