Bioprosthetic Replacement Research Articles

LEFT VENTRICULAR OUTFLOW TRACT OBSTRUCTION RELATED TO MITRAL VALVE SURGERIES IN HYPERTROPHIC CARDIOMYOPATHY PATIENTS

Symptomatic left ventricular outflow tract (LVOT) obstruction in hypertrophic cardiomyopathy (HCM) patients may develop after mitral valve (MV) surgery. We present two such cases treated with alcohol septal ablation (ASA). A 77-year-old woman who had received bioprosthetic MV replacement presented

The effects of decellularization and cross-linking techniques on the fatigue life and calcification of mitral valve chordae tendineae

In cases of severely diseased mitral valves (MV), the required treatment is often valve replacement. Bioprosthetic and stentless replacement valves are usually either fully or partially composed of animal derived tissue treated with a decellularization process, a cross-linking process, or both. In this study, we analysed the effects of these treatments on the fatigue properties of porcine MV chordae tendineae (CT), as well as on the calcification of the CT using an in vitro technique. CT were tested in 4 groups; (1) native, (2) decellularized (DC), (3) decellularized and cross-linked with glutaraldehyde (DC-GTH), and (4) decellularized and cross-linked with 1-ehtyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)(DC-EDC). CT were tested in both uniaxial tension, and in fatigue at 10MPa peak stress (1Hz). The cycles to failure (mean±SD) for the four groups are as follows; Native- 53,397±55,798, DC- 28,013±30,634, DC-GTH- 97,665±133,556, DC-EDC- 318,601±322,358. DC-EDC CT were found to have a slightly longer fatigue life than the native and DC groups. The DC-EDC group also had a marginally lower dynamic creep rate, meaning those CT elongate more slowly. After in vitro calcification, X-ray microtomography was used to determine relative levels of calcification. The DC-EDC and DC-GTH groups had the lowest volume of calcific deposits. Under uniaxial testing, the ultimate tensile strength (UTS) of the DC-GTH CT was statistically significantly reduced after calcification, while the UTS was relatively unchanged for the DC-EDC group. Overall, these results indicate that a treatment of decellularization plus cross-linking with EDC may improve the fatigue life of porcine CT, reduce the rate of elongation, and help the CT resist the negative effects of calcification. This may be a preferable treatment in the preparation of porcine MVs for the replacement of diseased MVs.

Sutureless 3f Enable valve implantation concomitant with mitral valve surgery.

Interest in aortic sutureless bioprostheses is growing. Here, we evaluate the feasibility of performing aortic sutureless valve replacement concomitant with mitral valve surgery using the 3f Enable prosthesis. Of the 198 3f Enable® valve implantation procedures carried out in our unit between March 2011 and October 2014, 15 were performed concomitant with mitral valve surgery (8 bioprosthetic replacements and 7 annuloplasties). The mean age and logistic EuroSCORE were 76 ± 6 years and 10.2 ± 4.8, respectively. The procedural success rate of aortic sutureless valve implantation was 100%. Mean cross-clamping and cardiopulmonary bypass times were 113.9 ± 35 and 150- ± 43 min, respectively. No reclamping in response to a sutureless paravalvular leakage (PVL) was needed. One grade 1 leak was observed at the time of discharge. There was no perioperative mortality. Pacemaker implantation was required in 1 case (6.6%). Initial follow-up (median = 8 months, range 1-6) showed no new aortic PVL; mean and peak transprosthetic gradients and the orifice area were 11.1 ± 2.5 and 18.4 ± 4.9 mmHg and 1.7 ± 0.4 cm(2), respectively. One grade 2 and two grade 1 mitral valve leaks were detected following annuloplasty. 3f Enable® sutureless valve implantation combined with mitral valve surgery appears feasible and the results presented here are encouraging. This procedure has the potential to simplify surgery in a cohort of high-risk patients for whom transcatheter aortic valve replacement is not an effective option. Larger studies should be conducted to confirm these observations.

An unusual cause of left ventricular outflow tract obstruction

Left ventricular outflow tract obstruction (LVOTO) has been reported with bio-prosthetic and mechanical mitral valves (MV), though it is more common with the former. The obstruction can be dynamic or fixed. We hereby report a case of fixed LVOTO following bio-prosthetic MV replacement (MVR).

Mitral valve repair or bioprosthetic replacement: The conundrum in Indigenous rheumatic mitral disease

Mitral valve repair or bioprosthetic replacement: The conundrum in Indigenous rheumatic mitral disease

Aortic Valve Leaflet Replacement with Bovine Pericardium to Preserve Native Dynamic Capabilities of the Aortic Annulus

Valve replacement is typically the most appropriate option for treating aortic valve stenotic insufficiency. However, neither mechanical nor bioprosthetic replacement components preserve the circumferential expansion and contraction of a native aortic annulus during the cardiac cycle, because the prosthetic ring is affixed to the annulus. A 64-year-old man presented with a bicuspid and stenotic aortic valve, and the native annulus was too small to accommodate a porcine replacement valve. We fashioned new aortic leaflets from bovine pericardium with use of a template, and we affixed the sinotubular junction with use of inner and outer stabilization rings. Postoperative echocardiograms revealed coaptation of the 3 new leaflets with no regurgitation. At the patient's 5.5-year follow-up examination, echocardiograms showed flexible leaflet movement with a coaptation height of 7 mm, and expansion and contraction of the aortic annulus similar to that of a normal native annulus. The transvalvular pressure gradient was insignificant. If long-term durability of the new leaflets is confirmed, this method of leaflet replacement and fixation of the sinotubular junction might serve as an acceptable alternative to valve replacement in the treatment of aortic valve stenosis. We describe the patient's case and present our methods and observations.

When should a mechanical tricuspid valve replacement be considered?

Isolated mechanical tricuspid valve replacement (mTVR) is uncommon, early mortality is reported to be high, and little is known regarding the long-term outcome. We sought to evaluate the long-term outcome of mTVR. From 1980 to 2007, isolated mTVR was performed in 64 patients (33 men) at our institution; themedian age was 45.5 years (6-71 years). There were 2192 tricuspid valve (TV) repairs and 137 isolated bioprosthetic TV replacements during the same time interval. Valve dysfunction was caused by congenital TV abnormality in 45 patients (70%), carcinoid heart disease in 13 (20%), traumatic TV regurgitation in 3(5%), and other reason in 3 (5%). Twenty-three patients (36%) had at least 1 previous cardiac procedure (TV repair in 8 and bioprosthetic TV replacement in 7). Mechanical prostheses used included Starr-Edwards (before 1993) in 36 patients (56%) and bileaflet prostheses in 28 (44%). Concomitant procedures included atrial septal defect closure in 28 (44%), arrhythmia surgery in 11 (17%), and pulmonary valvectomy for carcinoid disease in 10 patients (16%). Early mortality occurred in 5 patients (7.8%). Early morbidity included a permanent pacemaker in 9 (14%) and reexploration for bleeding in 2 patients (3%). Mean follow-up was 6 years (maximum 22.4 years). Five- and 10-year survival was 65% and 58%, respectively. There was no valve-related mortality. Late morbidity included valve thrombosis in 5 patients (8%); 3 were managed nonoperatively and 2 underwent TV rereplacement. Isolated mTVR still leads to increased early mortality. A mechanical valve can be considered inselect situations when anticoagulation is necessary and in the presence of good right ventricular function.

Minimally invasive tricuspid valve surgery in patients at high risk

Reports of minimally invasive tricuspid valve operations are rare, and results are often contradictory. This study analyzes our 5-year experience with minimally invasive tricuspid valve operations in high-risk patients. Between November 2005 and December 2011, tricuspid valve surgery using a nonsternotomy minimally invasive technique was performed in 64 patients (19 male, 45 female; mean age, 63.2±12.8years). Mean preoperative European System for Cardiac Operative Risk Evaluation was 7.3±2.9, and predicted mortality was 11.6%±11.7%. Tricuspid valve regurgitation cause was functional in 36 patients (56.2%), endocarditis in 2 patients (3.1%), and rheumatic in 24 patients (37.5%). Two patients (3.1%) showed prosthesis dysfunction. Forty patients (62.5%) had undergone previous cardiac surgery. Tricuspid valve repair was performed in 35 patients (54.7%). Tricuspid valve replacement with bioprosthesis was performed in 27 patients (42.2%), and the remaining 2 patients (3.1%) underwent bioprosthetic replacement. Concomitant procedures (48) included mitral valve surgery (42 patients), atrial septal defect closure (5 patients), and myxoma exeresis (1 patient). Conversion to sternotomy occurred in 1 patient (1.6%). Overall hospital mortality was 7.9%. Stroke occurred in 1 patient (1.6%), and 5 patients underwent reoperation for bleeding (7.8%). Mean follow-up time was 21±16months (range, 1-59months) and 100% completed. Cumulative Kaplan-Meier estimated 5-year survival was 81.3%, and 5-year freedom from reoperation was 100%. The heart-port-based minimally invasive approach seems to be safe, feasible, and reproducible in case of tricuspid valve operations. It ensures low perioperative morbidity, moderate to low rates of tricuspid regurgitation recurrence, and low late mortality. It also seems to have an added value in case of reoperative procedures.

Mitral valve repair and bioprosthetic replacement without postoperative anticoagulation does not increase the risk of stroke or mortality

The study aimed to determine if mitral valve repair (MVRR) or bioprosthetic mitral valve replacement (BMVR) without postoperative anticoagulation is associated with a similar risk of thromboembolism and death as anticoagulation. We retrospectively reviewed our 2004-09 experience in 249 MVRR and bioprosthetic replacement patients (53% female; 63 year mean age). Concurrent procedures principally included antiarrhythmic surgery, aortic valve replacement, tricuspid valve repair and coronary bypass grafting. Warfarin therapy was instituted at the discretion of the surgeon. Thirty-day, a period known to have the highest risk of valve-related thromboembolism, outcomes were compared relying on the incidence of stroke and death as surrogates of thromboembolic complications. Intermediate-term survival was compared between the groups using Cox proportional hazard models. The mean follow-up was 2.9 years. Given the non-randomized warfarin use, a propensity score using patient comorbidities and concurrent procedures was created and added to the Cox models. One hundred and ninety-two (77%) patients were discharged on warfarin and 57 (23%) were discharged without warfarin. Thirty-day mortality in patients discharged from the index hospitalization was 1.2% and was similar for the two groups (P = 0.99). Four ischaemic perioperative strokes were detected; 3 in the warfarin group and 1 in the no warfarin group (P = 0.99). Overall survival was 84%, with 84% survival in the warfarin group and 86% in the no warfarin group (P = 0.79). Bleeding complications were comparable between the two groups (P = 0.72). In a multivariate analysis, warfarin was not related to mortality. Despite current guidelines recommending postoperative anticoagulation following MVRR or bioprosthetic replacement, the avoidance of warfarin does not increase perioperative complications and has no impact on intermediate survival. Accordingly, a prospective randomized study to adjudicate the role of extended warfarin thromboprophylaxis in mitral valve surgery is warranted.

Comparison between homografts and Freestyle(R) bioprosthesis for right ventricular outflow tract replacement in Ross procedures

Although data from large series indicate the satisfactory performance of bioprosthetic valves in the right ventricular outflow tract (RVOT), replacement of the pulmonary valve in adult patients undergoing the Ross procedure is usually performed with pulmonary allografts. We evaluated the outcomes of homografts vs. bioprosthetic RVOT replacement after the Ross procedure in adults. Between 1996 and 2011, a total of 186 adult patients (141 male; mean age 44 ± 10 years) underwent aortic root replacement with a pulmonary autograft. The RVOT was replaced with a homograft in 113 patients and with stentless bioprostheses (Medtronic Freestyle(®)) in 73. Patients were followed for a mean of 6 years (range 1-15 years; 1106 patient years). Twelve patients required reintervention owing to dysfunction of the RVOT replacement, which was caused by endocarditis (n = 4), degeneration (n = 2) or stricture at the proximal suture line (n = 6). For homografts, the incidence of reintervention was 1 in 150 patient years, compared with 1 in 36 patient years for stentless bioprostheses (P = 0.007). The median gradient was 15 mmHg for the homograft group and 24 mmHg for bioprosthesis (P < 0.0001). The incidence of gradients >40 mmHg was 10-fold higher in the bioprosthetic group. Patients with bioprostheses in the RVOT position after the Ross procedure showed a significantly higher risk of reintervention or pulmonary valve dysfunction. The main problem, early development of a stricture at the proximal suture line, has to be solved to achieve satisfactory bioprosthetic function in the RVOT.

Clinical Impact of Concomitant Tricuspid Valve Procedures During Left Ventricular Assist Device Implantation

Almost 50% of patients referred for implantable left ventricular assist device (LVAD) have significant tricuspid regurgitation (TR). Preoperative TR is associated with negative outcomes but the clinical benefit of concomitant tricuspid valve procedures has not been extensively studied. One hundred fifteen patients, undergoing implantable LVADs, were identified as having significant TR by echocardiography prior to their surgical procedure. Patients underwent either LVAD alone (n = 81) versus LVAD plus concomitant tricuspid procedures (n = 34) (29 annuloplasty ring repairs and 5 bioprosthetic replacements.) Preoperative characteristics and hemodynamics, as well as TR severity and clinical outcomes were retrospectively determined from chart and database review and compared for the two groups. Preoperative characteristics and hemodynamics were similar for the two groups. Postoperative TR was markedly reduced for the group undergoing concomitant procedures versus LVAD alone. A temporary right ventricular assist device was required for only one of the 34 cases in which concomitant tricuspid procedures were performed; for patients undergoing LVAD alone, 8 of 81 required right ventricular assist devices. Mean duration of postoperative inotrope utilization was increased for the LVAD alone group versus the group with concomitant tricuspid procedures (10.0 vs 8.0 days, respectively, p = 0.04). The incidence of postoperative renal dysfunction was increased for the LVAD alone group (39%) versus concomitant procedures (21%) (p = 0.05). The LVAD alone group also had a greater mean postimplant length of hospitalization versus the concomitant procedures group (26.0 vs 19.0 days, p = 0.02). Finally, there was a trend toward improved survival for the group with concomitant tricuspid procedures versus LVAD alone. For patients with significant TR undergoing implantable LVAD procedures, concomitant tricuspid procedures are associated with improved early clinical outcomes.

Long-Term Survival for Patients With Preoperative Renal Failure Undergoing Bioprosthetic or Mechanical Valve Replacement

The objective of this study was to assess short-term and long-term outcomes after valve replacement with biologic or mechanical prostheses in patients with preoperative end-stage renal disease on chronic dialysis. A retrospective review of patients with end-stage renal disease undergoing valve replacement from January 1996 through March 2008 at Emory Healthcare Hospitals was performed. Outcomes were compared using χ(2) tests and 2-sample t tests. Adjusted long-term survival up to 10 years was assessed with Kaplan-Meier plots and compared between biologic and mechanical replacements using the Cox proportional hazards model. A total of 202 patients underwent 211 valve replacement operations. Patient age was 20 to 83 years (mean age, 54.8 ± 14.0); 115 of 211 (54.5%) were male. Operations included the following: 100 of 211 (47.4%) isolated aortic; 49 of 211 (23.2%) isolated mitral; 4 of 211 (1.9%) isolated tricuspid; and 58 of 211 (27.5%) combined replacements. Thirteen (6.2%) patients underwent reoperative valve replacements. Most patients received bioprosthetic valves (143 of 211, 67.8%), while 68 of 211 (32.2%) received mechanical valves. Concomitant coronary artery bypass was performed in 53 of 211 (25.1%) patients. Thirty-day mortality was in 42 of 211 patients (19.9%) and was not different between bioprosthetic and mechanical replacements. Overall 10-year survival was 18.1% for all patients and was not influenced by valve type implanted. For patients with end-stage renal disease treated with dialysis, valve replacement carries acceptable operative mortality. Long-term survival is similar among patients receiving bioprosthetic versus mechanical valve replacement. Careful risk assessment and choice of valve prosthesis should be performed prior to surgical intervention in this high-risk patient population.

Long Term Outcomes of Isolated Mitral Valve Surgery for Rheumatic Heart Disease in the Young: New Zealand 1990–2006

Background: Mitral valve (MV) repair offers potential advantages over replacement in patients with Rheumatic Heart Disease (RHD). This retrospective study compares the outcomes of isolated MV repair, mechanical and bioprosthetic replacement.

Late Outcomes of Cardiac Surgery for Rheumatic Heart Disease in the Young: The New Zealand Experience 1990–2006

Background: Valve repair offers potential advantages over replacement in patients with Rheumatic Heart Disease (RHD). This study compares the outcomes of mechanical valve replacements to valve repair and bioprosthetic replacements.

Composite Freestyle Stentless Xenograft With Dacron Graft Extension for Ascending Aortic Replacement

The present study was undertaken to evaluate clinical, hemodynamic, and morphologic results of composite stentless xenograft with polyethylene terephthalate fiber (Dacron; DuPont, Wilmington, DE) graft extension for combined replacement of the aortic valve, root, and ascending aorta. Between 1997 and 2008, 55 consecutive patients (33 men, 71 +/- 11 years) underwent ascending aortic replacement using Medtronic Freestyle with Dacron graft extension (DuPont). Indications included aneurysm (n = 31, 56%), dissection (n = 16, 29%), and endocarditis (n = 8, 15%). Associated procedures were performed in 25 patients (46%). Preoperative logistic EuroSCORE averaged 34% +/- 28%. Mean cardiopulmonary bypass and aortic cross-clamp times were 244 +/- 134 minutes and 162 +/- 69 minutes, respectively. Clinical follow-up was 100% complete and averaged 2 +/- 3 years. Early mortality was 0% (n = 0) in patients with a preoperative EuroSCORE of less than 20 (n = 26, mean expected mortality, 13% +/- 5%) and 31% (n = 9) in those with preoperative logistic EuroSCORE of at least 20 (n = 29, mean expected mortality, 52% +/- 28%). One- and 3-year survival rates were 83% +/- 5% and 78% +/- 7%, respectively. No major thromboembolic or spontaneous bleeding events were recorded. One patient (2%) required late reoperation for prosthetic valve endocarditis. Echocardiographic follow-up showed no valve dysfunction and low mean transvalvular gradients (7 +/- 5 mm Hg). A 64-channel computed tomographic scan was performed in 33 patients at 32.4 +/- 34 months and revealed two small pseudoaneurysms in a single patient. Composite Freestyle with Dacron graft extension appears to be a safe option for bioprosthetic replacement of the aortic root and tubular ascending aorta. However, long-term results using this composite graft will have to be determined.

Trends in Mitral Valve Surgery in the United States: Results From The Society of Thoracic Surgeons Adult Cardiac Database

The purpose of this study is to examine trends in mitral valve (MV) repair and replacement surgery using The Society of Thoracic Surgeons Adult Cardiac Surgery Database (STS ACSD). The study population included isolated mitral valve operations performed between January 2000 and December 2007 at 910 hospitals participating in the STS ACSD. Patients with endocarditis, prior cardiac operation, shock, emergency operation, and concomitant coronary artery bypass graft or aortic valve surgery were excluded. During the 8-year study period, 58,370 patients underwent isolated primary MV operations. For patients with isolated mitral regurgitation (n = 47,126), the rate of MV repair (versus replacement) increased from 51% to 69% (p < 0.0001). Among patients having replacement (n = 24,404), there has been a pronounced decline in the use of mechanical valves: 68% to 37% (p < 0.0001). The operative mortality for MV replacement was consistently higher than that for repair (3.8% versus 1.4%), a finding that persisted after risk-adjustment (adjusted odds ratio 0.52, 95% confidence interval: 0.45 to 0.59; p < 0.0001). Among patients having elective isolated MV repair (n = 28,140), the operative mortality was 1.2%. For asymptomatic (class I) patients, operative mortality was 0.6%. This study documents several important trends in MV surgery, including the progressive adoption of mitral valve repair and increasing use of bioprosthetic replacement valves. Operative risks of MV repair are significantly lower than those for MV replacement. Operative mortality for isolated elective mitral valve repair is 1% in contemporary clinical practice.

Mechanical Properties of Surgical Glues Used in Aortic Root Replacement

Surgical glues are used in mechanical, stentless bioprosthetic, and homograft aortic root replacements to seal and reinforce anastomotic suture lines. The aortic root normally undergoes substantial physiologic dilation and may be affected by the stiffness of applied sealants. We determined the material properties of four common commercial glues, comparing them with known properties of aortic root replacements. Samples of BioGlue (CryoLife, Inc, Kennesaw, GA), CoSeal (Baxter Healthcare International, Palo Alto, CA), Tisseel (Baxter Healthcare Corp, Glendale, CA), and Crosseal (OMRIX Biopharmaceuticals, Inc, New York, NY) sealants underwent biaxial tensile testing. A Hookean strain energy function was fit to the stress-strain response of each sample, and the Young's modulus was obtained for comparison of material stiffness. Sealants demonstrate a relatively linear response to loading; mean elastic moduli for BioGlue (3,122.04 +/- 1,639.68 kPa), CoSeal (100.02 +/- 67.60 kPa), Tisseel (102.59 +/- 41.13 kPa), and Crosseal (53.56 +/- 32.59 kPa) varied greatly. CoSeal and Tisseel have no significant difference in stiffness (p = 0.897) while Crosseal is more compliant than Tisseel (p = 0.004) and CoSeal (p = 0.055). BioGlue is stiffer than CoSeal, Tisseel, and Crosseal (p < 0.001). Furthermore, BioGlue is much stiffer than cited properties of Dacron grafts, glutaraldehyde-fixed porcine roots, and human aortic tissue. However, CoSeal and Tisseel are much more compliant than the aortic root conduits. BioGlue is much less compliant than the other sealants studied and materials available for aortic root replacement. A surgeon's choice of glue should be determined by stiffness as well as sealant efficacy. Sealants with greater stiffness than aortic root replacement material may restrict normal physiologic dilation and cause anastomotic strictures.

Invited Commentary

Dr LeMaire discloses a financial relationship with Ethicon Biosurgicals and Baxter Healthcare. Dr LeMaire discloses a financial relationship with Ethicon Biosurgicals and Baxter Healthcare. During the past decade, there has been a substantial increase in the number of surgical adhesives and sealants available for use in cardiovascular operations. As new products and new information about benefits and risks become available, surgeons constantly need to adjust their algorithms for deciding when to use each agent. Key considerations in these algorithms include the agent's effectiveness, safety, and cost. In this report, Azadani and colleagues [1Azadani A.N. Matthews P.B. Ge L. et al.Mechanical properties of surgical glues used in aortic root replacement.Ann Thorac Surg. 2009; 87: 1154-1160Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar] describe important quantitative differences in the stiffness and elasticity of several adhesives and sealants, and the authors make the case that the mechanical properties of a product should also be considered when adhesives and sealants are selected. Although the authors have chosen to discuss their results in the context of aortic root replacement, their findings have implications for many types of cardiovascular and thoracic operations. Both Tisseel (Baxter, Deerfield, IL) and BioGlue (CryoLife Inc, Kennesaw, GA) are widely used in aortic dissection repair to glue the inner dissecting membrane to the outer aortic wall, thereby obliterating the false lumen. This technique, which effectively sandwiches the adhesive between layers of aortic tissue, can profoundly alter the mechanical properties of the aorta. These agents are marketed for use not only in aortic repairs but also in peripheral vascular, pulmonary, and esophageal procedures; in all of these areas, a mismatch between adhesive and tissue compliance can lead to complications. For example, sealants and adhesives are used on the surface of the lung to reduce postoperative air leaks, but if an agent is unable to expand and contract with the lung throughout the respiratory cycle, it is unlikely to maintain an effective seal. The authors' objective findings about the differing mechanical properties of these agents corroborate the subjective differences observed by surgeons who have used them. Of particular concern are the findings that the stiffness of BioGlue was at least 30 times greater than that of the other products tested, and its elasticity was significantly less than that of aortic tissue or commonly used aortic replacement conduits. In considering the clinical implications of their findings, the authors suggest that, “the high stiffness of BioGlue as demonstrated in this study may result in an elevated wall stress which could additionally weaken the tissue and predispose to late pseudoaneurysm formation.” Several reports have described pseudoaneurysms and redissections that occurred after BioGlue was used for ascending aortic repair. Ngaage and colleagues [2Ngaage D.L. Edwards W.D. Bell M.R. Sundt T.M. A cautionary note regarding long-term sequelae of biologic glue.J Thorac Cardiovasc Surg. 2005; 129: 937-938Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar], for example, recently reported nearly circumferential disruption of both the proximal and distal anastomoses after ascending aortic dissection repair. Although the role of the glue in the anastomotic failure was primarily attributed to the intense local inflammatory process the glue caused, the strain placed on the anastomosis as the relatively compliant aortic wall and prosthetic graft pulsated against a noncompliant ring of adhesive may also have been a factor. Although adhesives and sealants can be extremely useful tools in the surgical armamentarium, Weissberg's words of caution remain salient: “Tissue adhesives are not innocuous when applied to the arterial wall. This … mitigates against [their] indiscriminate use” [3Weissberg D. Surgical glue and necrosis of arterial wall.Ann Thorac Surg. 2003; 75 ([letter]): 1063Abstract Full Text Full Text PDF PubMed Google Scholar]. By examining the mechanical limitations of existing products and discussing their potential clinical implications, Azadani and colleagues remind us of the importance of ongoing efforts to develop better surgical adhesives and sealants. Mechanical Properties of Surgical Glues Used in Aortic Root ReplacementThe Annals of Thoracic SurgeryVol. 87Issue 4PreviewSurgical glues are used in mechanical, stentless bioprosthetic, and homograft aortic root replacements to seal and reinforce anastomotic suture lines. The aortic root normally undergoes substantial physiologic dilation and may be affected by the stiffness of applied sealants. We determined the material properties of four common commercial glues, comparing them with known properties of aortic root replacements. Full-Text PDF

Bioprosthetic replacement of the ascending thoracic aorta: what are the options?

Increasing patient age and improved durability of latest generation bioprostheses have stimulated the use of bioprosthetic devices in the setting of ascending aortic replacement as an alternative to mechanical valved conduits or aortic valve-sparing procedures. We performed an English literature review to assess different surgical options that have been described for bioprosthetic replacement of the ascending aorta. Reported options include: (1) composite valved conduits using a stented bioprosthesis; (2) composite valved conduits using a stentless bioprosthesis; (3) total xenopericardial valved conduits. Composite valved grafts using stented bioprostheses offer a safe and durable option for bioprosthetic replacement of the ascending aorta. Other options are of more recent use and await medium-term results.

Nitric Oxide‐Mediated Growth Inhibition of an Endothelialized Tissue Engineered Aortic Valve

The tissue engineering (TE) of aortic valves may provide an alternative to the use of non‐viable bioprosthetic replacements. Endothelialization of a TE construct is necessary to establish a non‐thrombogenic surface and has been shown to inhibit the proliferation of vascular smooth muscle cells within the construct. Previously it has been shown that nitric oxide (NO) production by endothelial cells may be responsible for this growth inhibition. To test this hypothesis, cells scaffold constructs (CSCs) were produced consisting of radial artery cells seeded onto small intestine submucosa. After one week in culture, an analog inhibitor of nitric oxide synthase, L‐iminoethyl‐L‐orthinine (L‐NIO, 100 μM) was added to either CSCs or endothelialiazed CSCs (ECSCs). Constructs were cultured for an additional week, followed by fixation and tissue thickness analysis by confocal microscopy. ECSC and CSC control groups were cultured for two weeks in the absence of L‐NIO. The presence of an endothelium (ECSCs) significantly inhibited growth of the construct, however, in the presence of L‐NIO, growth of the construct continued in a manner similar to CSCs (75.6μ m vs 55.3μm). Results suggest that the production of NO by the endothelium may be responsible for growth inhibition of the ECSCs providing a valuable tool for controlling TE valve construct thickness in vitro. Funding provided by Heart and Stroke foundation of Ontario.