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Biomedical subjects

Ronald C Elkins

Publications and source records attributed to Ronald C Elkins.

5 recordsLinked to original sources
PubMed2003

Is tissue-engineered heart valve replacement clinically applicable?

Tissue engineering of a heart valve has progressed dramatically in three different arenas: a biodegradable stented valve seeded with autogenous cells, decellularized allograft and xenograft valves that are seeded with autogenous cells, and decellularized allograft and xenograft valves that repopulate by adaptive remodeling in vivo. Preclinical evaluation and implants in sheep have been accomplished in each of these arenas, and clinical use of this emerging technology is occurring in the latter two. The clinical use of decellularized allografts that repopulate in vivo is expanding; however, its impact on allograft durability remains unknown.

Aortic Valve↗
PubMed2003

Prognosis after aortic root replacement with cryopreserved allografts in adults.

BACKGROUND: Aortic root replacement with cryopreserved allografts is associated with excellent hemodynamics, little endocarditis, low thromboembolic event rates, and no need for anticoagulation. There is, however, concern regarding the long-term durability of this valve substitute, especially in younger patients. Meta-analysis and microsimulation were used to calculate age-specific long-term prognosis after allograft aortic root replacement based on current evidence. METHODS: Our center's experience with cryopreserved allograft aortic root replacement in 165 adult patients was combined in a meta-analysis with reported and individual results from four other hospitals. Using this information, the microsimulation model predicted age- and gender-specific total and reoperation-free and event-free life expectancy. RESULTS: The pooled results comprised 629 patients with a total follow-up of 1860 patient-years (range 0 to 12.8 years). Annual risks were 0.6% for thromboembolism, 0.05% for bleeding, 0.5% for endocarditis, and 0.5% for nonstructural valve failure. Structural allograft failure requiring reoperation occurred in 15 patients, and a patient age-specific Weibull function was constructed accordingly. Calculated total life expectancy varied from 27 years in a 25-year-old to 12 years in a 65-year-old male; corresponding actual lifetime risk of reoperation was 89% and 35%, respectively. CONCLUSIONS: Cryopreserved aortic allografts have an age-related limited durability. This results in a considerable lifetime risk of reoperation, especially in young patients. The combination of meta-analysis and microsimulation provides an appropriate tool for estimating individualized long-term outcome after aortic valve replacement and can be useful both for patient counseling and prognostic research purposes.

Adolescent↗
PubMed2003

Pulmonary autografts in patients with severe left ventricular dysfunction.

BACKGROUND: Performing a Ross operation in patients with severe left ventricular dysfunction is controversial. The objective in this retrospective study was to determine the outcome of 15 patients with aortic valve disease (11 had aortic insufficiency and 4 had aortic insufficiency and aortic stenosis) associated with reduced left ventricular function (ejection fraction < 40%) treated with a pulmonary autograft. METHODS: We identified 15 patients with severe left ventricular dysfunction from 226 consecutive pulmonary autograft procedures done between age 18 and 50 years from 1986 to 2001. Patients had documented preoperative ejection fraction less than 40% and were in New York Heart Association class III or IV. Preoperative ejection fraction ranged from 18% to 37% (mean, 31% +/- 6.5%). Transthoracic echocardiograms obtained preoperatively and at 1-week, 6-month, and 1- and 2-year intervals were reviewed. Records were evaluated for survival, clinical status, left ventricular function, and valve function. RESULTS: There were no operative deaths, late deaths, or reoperations. All patients had follow-up examinations within the past year and are clinically well (67% > 2 years follow-up). Ten of 15 patients (67%) had substantially improved ventricular function (> 20% increase). The average ejection fraction increased from 31% +/- 7% preoperatively to 51% +/- 11% at 2 years, and the increase is significant from 1 week on (p < 0.02). Average left ventricular mass index decreased by 41% at 6 months (n = 10; p = 0.009) and by 44% at 2 years (n = 9; p = 0.02). Mean Z values for left ventricular mass decreased from 7.6 to 3.6 after more than 2 years (p = 0.007). CONCLUSIONS: The Ross operation is an appropriate option in adults age 50 or younger in the presence of decreased left ventricular ejection fraction. Neither operative mortality nor postoperative sequelae were identified in our subset of patients. Excellent survival and ventricular recovery are predicted.

Adult↗
PubMed2003

Effect of prior aortic valve intervention on results of the Ross operation.

BACKGROUND AND AIM OF THE STUDY: Patient-related factors, aortic insufficiency, bicuspid aortic valve, aortic annulus dilatation, ascending aortic dilatation or aneurysm, and aortic valve endocarditis have been suggested as affecting the results of the Ross operation. The study aim was to assess the impact of prior aortic valve intervention on early and late results of a Ross operation. METHODS: A total of 399 patients who underwent surgery between August 1986 and September 2000 were reviewed retrospectively. The patients were grouped as: no prior aortic valve intervention (NOAVI, n = 219); prior aortic valvuloplasty (AVP, n = 106); prior balloon aortic valvuloplasty (AVB, n = 40); and prior aortic valve replacement (AVR, n = 34). Details of operative and late mortality, autograft valve function, and homograft valve function were analyzed. RESULTS: Operative mortality was higher for AVB (10%; three deaths in neonates) than the other groups (from 2.3% to 5.9%) (p = 0.084). Freedom from autograft valve degeneration, defined as severe autograft valve insufficiency, non-endocarditis autograft valve reoperation or valve-related death, ranged from 93 +/- 3% for AVP to 76 +/- 8% for NOAVI at 10 years (p = 0.43). Freedom from homograft reoperation in the pulmonary position was 100% for AVB at six years, and 99 +/- 1% for AVP, 82 +/- 8% for NOAVI, and 70 +/- 13% for AVR at 10 years (p = 0.0026). CONCLUSION: There appears to be no significant difference between patients with and without prior aortic valve surgery, with respect to operative mortality or late autograft function. However, patients with prior AVR appear to have a significantly higher homograft reoperation rate after a Ross operation, the reasons for which are uncertain.

Adolescent↗