Twenty-Five–Year Experience With the Medtronic-Hall Valve Prosthesis in the Aortic Position

Tunable Elastomers with an Antithrombotic Component for Cardiovascular Applications

This study reports the development of a novel family of biodegradable polyurethanes for use as tissue engineered cardiovascular scaffolds or blood-contacting medical devices. Covalent incorporation of the antiplatelet agent dipyridamole into biodegradable polycaprolactone-based polyurethanes yields biocompatible materials with improved thromboresistance and tunable mechanical strength and elasticity. Altering the ratio of the dipyridamole to the diisocyanate linking unit and the polycaprolactone macromer enables control over both the drug content and the polymer cross-link density. Covalent cross-linking in the materials achieves significant elasticity and a tunable range of elastic moduli similar to that of native cardiovascular tissues. Interestingly, the cross-link density of the polyurethanes is inversely related to the elastic modulus, an effect attributed to decreasing crystallinity in the more cross-linked polymers. In vitro characterization shows that the antiplatelet agent is homogeneously distributed in the materials and is released slowly throughout the polymer degradation process. The drug-containing polyurethanes support endothelial cell and vascular smooth muscle cell proliferation, while demonstrating reduced levels of platelet adhesion and activation, supporting their candidacy as promising substrates for cardiovascular tissue engineering.

Standardized Definition of Structural Valve Degeneration for Surgical and Transcatheter Bioprosthetic Aortic Valves

Bioprostheses are prone to structural valve degeneration, resulting in limited long-term durability. A significant challenge when comparing the durability of different types of bioprostheses is the lack of a standardized terminology for the definition of a degenerated valve. This issue becomes especially important when we try to compare the degeneration rate of surgically inserted and transcatheter bioprosthetic valves. This document, by the VIVID (Valve-in-Valve International Data), proposes practical and standardized definitions of valve degeneration and provides recommendations for the timing of clinical and imaging follow-up assessments accordingly. Its goal is to improve the quality of research and clinical care for patients with deteriorated bioprostheses by providing objective and strict criteria that can be utilized in future clinical trials. We hope that the adoption of these criteria by both the cardiological and surgical communities will lead to improved comparability and interpretation of durability analyses.

Karl Viktor Hall: From In Situ Vein Bypass to the Tilting Disc Heart Valve Prosthesis

In 1977, Karl Viktor Hall implanted a novel tilting disc heart valve prosthesis at Rikshospitalet in Oslo, Norway. The Medtronic-Hall valve was known for its excellent durability and low thrombogenicity. Hall popularized the use of the great saphenous vein in situ as an arterial shunt in the 1960s, made a metal stripper to lyse vein valves, and introduced electromagnetic flowmeters in vascular surgery. He performed the first coronary artery bypass graft in Scandinavia in 1969. Under his leadership the first heart transplantation and the first heart-lung transplantation were performed in Scandinavia by his successor Tor Frøysaker in 1983 and 1986, respectively.

Prognosis after surgical replacement with a bioprosthetic aortic valve in patients with severe symptomatic aortic stenosis: systematic review of observational studies

OBJECTIVE

 To determine the frequency of survival, stroke, atrial fibrillation, structural valve deterioration, and length of hospital stay after surgical replacement of an aortic valve (SAVR) with a bioprosthetic valve in patients with severe symptomatic aortic stenosis.

DESIGN

 Systematic review and meta-analysis of observational studies.

DATA SOURCES

 Medline, Embase, PubMed (non-Medline records only), Cochrane Database of Systematic Reviews, and Cochrane CENTRAL from 2002 to June 2016.

STUDY SELECTION

 Eligible observational studies followed patients after SAVR with a bioprosthetic valve for at least two years.

METHODS

 Reviewers, independently and in duplicate, evaluated study eligibility, extracted data, and assessed risk of bias for patient important outcomes. We used the GRADE system to quantify absolute effects and quality of evidence. Published survival curves provided data for survival and freedom from structural valve deterioration, and random effect models provided the framework for estimates of pooled incidence rates of stroke, atrial fibrillation, and length of hospital stay.

RESULTS

 In patients undergoing SAVR with a bioprosthetic valve, median survival was 16 years in those aged 65 or less, 12 years in those aged 65 to 75, seven years in those aged 75 to 85, and six years in those aged more than 85. The incidence rate of stroke was 0.25 per 100 patient years (95% confidence interval 0.06 to 0.54) and atrial fibrillation 2.90 per 100 patient years (1.78 to 4.79). Post-SAVR, freedom from structural valve deterioration was 94.0% at 10 years, 81.7% at 15 years, and 52% at 20 years, and mean length of hospital stay was 12 days (95% confidence interval 9 to 15).

CONCLUSION

 Patients with severe symptomatic aortic stenosis undergoing SAVR with a bioprosthetic valve can expect only slightly lower survival than those without aortic stenosis, and a low incidence of stroke and, up to 10 years, of structural valve deterioration. The rate of deterioration increases rapidly after 10 years, and particularly after 15 years.

Repair options in rheumatic aortic valve disease in young patients: potential problems with pericardial cusp extension

This article outlines the arguments against cusp extension, which were put forward at the debate entitled "Repair options in rheumatic aortic disease in young patients" at the Symposium on Surgery for Rheumatic Heart Disease organized by The World Society for Pediatric and Congenital Heart Surgery at The Sixth World Congress of Paediatric Cardiology and Cardiac Surgery, February 17-22, 2013, Cape Town, South Africa. We propose that cusp extension should be avoided because (1) these patients are usually old enough to receive the same valve substitutes as adults, (2) lack of antibioprophylaxis compliance will likely result in early reintervention, (3) cusp extension mandates rerepair within four to five years and is more expensive in the long term, and (4) it is fraught with myocardial ischemic complications. Thus, a mechanical, bioprosthetic, or autograft valve replacement may be superior for patients unless they have unrestricted access to repetitive interventions. A single surgical technique does not suffice in the treatment of rheumatic aortic valve disease, and a diversified approach should be adopted dependent on both the patients' characteristics and the financial constraints.

Influence of prosthesis type on long-term survival after re-replacement of aortic valve prosthesis

BACKGROUND

The purpose of this study is to examine the influence of the prosthesis type on early mortality and long-term survival after re-replacement of aortic valve prosthesis, especially in patients over 60 years old.

METHODS

Late outcome of 223 patients who underwent a reoperation on the aortic valve and received a mechanical (mechanical group) or biological (biological group) heart valve prosthesis at a single institution were analyzed for survival and major valve-related complications, including structural valve deterioration, thromboembolism, hemorrhage, further reoperation, and valve-related mortality.

RESULTS

Preoperative New York Heart Association class IV (P = 0.001), emergency procedure (P = 0.002), and endocarditis (P = 0.025) were significant risk factors for 30-day mortality rates, which were 8.4 % and 12.5 %, respectively (mechanical versus biological group, P = 0.361). A subanalysis of elective patients revealed a low risk of 30-day mortality of 2.4 % and 1.8 %, respectively. Event-free survival was comparable at 5 years (73.9% ± 3.6% versus 70.5% ± 6.5%, mechanical versus biological group) and 10 year (49.7% ± 5.0% versus 35.3% ± 9.8%, mechanical versus biological group). In a propensity-matched subanalysis, survival and event-free survival were comparable at 5 and 10 years in both groups.

CONCLUSION

The type of aortic valve prosthesis did not affect early outcome and late survival in patients who underwent valve replacement, and therefore, the current strategy favoring a biological aortic valve prosthesis for patients aged over 60 years in first-time operations could also be applied in re-replacement.

Thirty-year results after implantation of the Björk-Shiley Convexo-Concave Heart valve prosthesis

BACKGROUND

Modifications of the Björk-Shiley valve prosthesis have shown good long-term results. The convexo-concave model, however, was recalled 27 years ago because of a propensity for breakage due to outlet strut fracture. The objective of this study is to describe the 30-year outcome after implantation of the Björk-Shiley convexo-concave mechanical heart valve prosthesis (Pfizer, Rye Brook, NY).

METHODS

The study included 279 patients who were operated between 1979 and 1983 at Turku University Hospital. A total of 305 valves were implanted; 205 in the aortic position and 100 in the mitral position. Patient records were reviewed for baseline characteristics and late events, data on mortality were acquired from registries.

RESULTS

Mean actuarial survival was 19.8 years and mean follow-up was 19.2 years (maximum 34 years). Freedom from reoperation was 91.3% at 30 years. There were 3 outlet strut fractures (2 fatal) during follow-up. Statistically significant predictors of mortality were age and concomitant coronary artery bypass grafting.

CONCLUSIONS

Despite the possibility of structural valve failure the Björk-Shiley convexo-concave valve confers excellent 30-year survival.

Prosthesis-sparing aortic root replacement following aortic valve replacement

Reoperation on the aortic root is considered to be challenging because of high hospital mortality. Prosthesis-sparing aortic root replacement, in which the aortic prosthesis is preserved during reoperation, and could avoid passing sutures through the weakened aortic annuls after the initial prosthesis has been removed. We report 3 cases of prosthesis-sparing aortic root replacement. Prior procedures were aortic valve replacement and the Bentall operation 14 to 35 years previously. Postoperative courses were uneventful, with no signs of pseudoaneurysm or valve malfunction observed during follow-up periods of 93 to 360 days.

Acute obstruction by Pannus in patients with aortic medtronic-hall valves: 30 years of experience

BACKGROUND

Acute dysfunction of mechanical aortic valve prostheses is a life-threatening adverse event. Pannus overgrowth, which is fibroelastic hyperplasia originating from the periannular area, is one cause of dysfunction. The aim of this study was to determine the annual incidence of readmittance resulting from acute obstruction caused by pannus during 30 years of observation in patients with Medtronic-Hall aortic valve prostheses and to analyze the risk factors associated with pannus development.

METHODS

From 1982 to 2004, 1,187 patients in our department underwent aortic valve replacement with Medtronic-Hall mechanical monoleaflet valve prostheses. As of December 31, 2012, 27 of these patients (2.3%) had presented with acute valve dysfunction caused by pannus obstruction.

RESULTS

The annual incidence of pannus was 0.7 per 1,000. The median time from the primary operation to prosthetic dysfunction was 11.1 years (range, 1.2 to 26.8 years). Of the 20 patients who underwent reoperation, 2 died. Seven patients died before reoperation. Women had a higher risk for the development of obstructing pannus, and patients with pannus obstruction were younger. Valve size was not an independent risk factor.

CONCLUSIONS

Women and younger patients are at higher risk for pannus development. When acute dysfunction by pannus is suspected in a mechanical aortic valve, an immediate echocardiogram and an emergency aortic valve replacement should be carried out because of the potential of a fatal outcome.

Episodic circulatory collapse caused by intermittent prosthetic aortic valve dysfunction

An 80-year-old woman with a 20-mm Medtronic Hall (tilting-disc) aortic prosthesis presented with episodes of chest pain associated with circulatory collapse and subsequent rapid spontaneous recovery. A computed tomography angiogram demonstrated no evidence of aortic dissection, pulmonary embolus, or coronary artery disease. A transthoracic echocardiogram demonstrated a well-functioning prosthetic aortic valve. After another inpatient episode, auscultation demonstrated an intermittent absence of the prosthetic second heart sound. A transesophageal echocardiography examination revealed that the aortic valve was intermittently sticking in the open position. During the emergency replacement, the existing valve was noted to have pannus and overlying thrombus, which are rare in this type of valve but can lead to dramatic circulatory collapse when present. This case demonstrates how a diagnosis of intermittent valve dysfunction can prove elusive. It is important, as part of the assessment of mechanical valves, to perform regular, careful auscultation and echocardiographic examination, with emphasis on recording in Doppler or M-mode through the valve at slow sweep speeds for a prolonged period in order to maximize the chance of diagnosing episodic valve dysfunction.

Choice of prosthetic heart valve in adults an update

In the last 7 years, more data have reconfirmed that patients' comorbid conditions are very important factors determining patient outcomes. Prosthetic heart valves (PHVs) that require aortic root replacement in the absence of aortic root disease are associated with poorer outcomes. For the vast majority of patients, the choice of PHV is between a mechanical valve and a stented bioprosthesis. The choice is largely dependent upon the age of the patient at the time of PHV implantation and on which complication the patient wants to avoid: specifically, anticoagulation therapy and its complications with the mechanical valve, and structural valve deterioration with a bioprosthesis. Data on the pros and cons of the choices and exceptions to the rules are discussed, and a new algorithm is developed.

Antithrombotic management of patients with prosthetic heart valves: current evidence and future trends

Over 4 million people worldwide have received a prosthetic heart valve, and an estimated 300,000 valves are being implanted every year. Prosthetic heart valves improve quality of life and survival of patients with severe valvular heart disease, but the need for antithrombotic therapy to prevent thrombotic complications in valve recipients poses challenges for clinicians and patients. Here, we review antithrombotic therapies for patients with prosthetic heart valves and management of thromboembolic complications. Advances in antithrombotic therapy and valve technologies are likely to improve the management of patients with prosthetic heart valves in developed countries, but the most important unmet need and potential for benefit from these new therapies is in developing countries where a massive and rapidly increasing burden of valvular heart disease exists.