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Biomedical subjects

David R Clarke

Publications and source records attributed to David R Clarke.

8 recordsLinked to original sources
PubMed2006

Birth weight and complexity are significant factors for the management of hypoplastic left heart syndrome.

BACKGROUND: Classic options for treatment of hypoplastic left heart syndrome include the Norwood procedure (NW) and heart transplantation (HT). Recently off-pump palliative procedures were introduced in the management of these patients. Risk factors influencing the decision between the NW with staged reconstruction or off-pump palliation and HT were assessed. METHODS: Between January 2002 and January 2006, 69 patients with hypoplastic left heart syndrome were referred for either a NW (n = 33) or HT (n = 36). Patients referred for HT underwent off-pump palliation (catheter-based, n = 20, or surgical hybrid procedures, n = 7) until a donor organ became available: including patent ductus arteriosus stenting (80.6%), atrial septostomy (41.7%), and branch pulmonary artery banding (55.6%). RESULTS: Heart transplantation patients were more complex, based on a higher Aristotle Comprehensive Complexity score calculated at birth (HT 18.8 +/- 2.4 versus NW 17.7 +/- 1.7; p < 0.05). Presurgical death was significantly greater for HT referrals (HT 27.8% versus NW 3.0%; p < 0.01); however, there was no difference between the two groups in operative (HT 11.5% versus NW 21.9%; not significant) or overall mortality (HT 36.1% versus NW 24.2%; not significant). No independent risk factors for death were identified with HT; however, a lower birth weight (<2.5 kg) and a higher Aristotle score (>20) correlated with surgical death with NW (p < 0.01). Noticeably, surgical survival was 85.7% for infants with birth weight of 2.5 kg or greater undergoing NW. CONCLUSIONS: Overall survival is similar for hypoplastic left heart syndrome patients referred for the NW or HT. Lower birth weight and higher complexity are risk factors for patients undergoing NW. Off-pump palliation followed by HT or further staged palliation should be considered for these high-risk hypoplastic left heart syndrome patients.

Apoptosis Regulatory Proteins↗
PubMed2006

Invited commentary.

Explore the source record for details and available documents.

Absorbable Implants↗
PubMed2006

Beam-supported AlN thin film bulk acoustic resonators.

A novel, suspended thin film bulk acoustic wave resonator (SFBAR) has been fabricated from an aluminum nitride film sputtered directly on a (100) silicon substrate. The suspended membrane design uses thin beams to support, as well as electrically connect, the resonator and has been fabricated using both thin film processing and bulk silicon micromachining. The quality factor and the effective electromechanical coupling coefficient were characterized as a function of the number and the length of the support beams. The length of the support beams was found to affect neither the quality factor at resonance nor the effective electromechanical coupling factor. However, longer support beams did facilitate better frequency pair response. Device performance varied with the number of support beams: 70% of the resonators tested showed a higher figure of merit with eight support beams than with four support beams.

Journal Article↗
PubMed2005

The Aristotle method: a new concept to evaluate quality of care based on complexity.

PURPOSE OF REVIEW: Evaluation of quality of care is a duty of the modern medical practice. A reliable method of quality evaluation able to compare fairly institutions and inform a patient and his family of the potential risk of a procedure is clearly needed. It is now well recognized that any method that purports to evaluate quality of care should include a case mix/risk stratification method. No valuable method was available until recently in pediatric cardiac surgery. RECENT FINDINGS: The Aristotle method is a new concept of evaluation of quality of care in congenital heart surgery based on the complexity of the surgical procedures. Involving a panel of expert surgeons, the project started in 1999 and included 50 pediatric surgeons from 23 countries. The basic score adjusts the complexity of a given procedure and is calculated as the sum of potential for mortality, potential for morbidity and anticipated technical difficulty. The Comprehensive Score further adjusts the complexity according to the specific patient characteristics (anatomy, associated procedures, co-morbidity, etc.). The Aristotle method is original as it introduces several new concepts: the calculated complexity is a constant for a given patient all over the world; complexity is an independent value and risk is a variable depending on the performance; and Performance = Complexity x Outcome. SUMMARY: The Aristotle score is a good vector of communication between patients, doctors and insurance companies and may stimulate the quality and the organization of heath care in our field and in others.

Benchmarking↗
PubMed2002

Surgical options and results of repeated aortic root replacement for failed aortic allografts placed in childhood.

OBJECTIVES: This report reviews our experience with repeated aortic root replacement after failure of cryopreserved aortic allografts placed during childhood and compares replacement with aortic allografts, pulmonary autografts, and mechanical valved conduits in these patients. METHODS: This was a retrospective analysis of all such patients from 1986 through May 2001. RESULTS: There were 25 operations (11 aortic allografts, 9 pulmonary autografts, and 5 mechanical valved conduits) among 23 patients. The mean time to reoperation was 6.3 years. There were 2 in-hospital deaths (8%, 1 patient with a pulmonary autograft and 1 with a mechanical valved conduit). There were 2 early nonfatal valve-related events (1 patient with an aortic allograft and 1 with a pulmonary autograft). There were no late valve-related deaths and 2 late non-valve-related deaths of patients with aortic allografts placed. No variable predicted early death or early valve-related event. No differences in preoperative characteristics, hospital variables, early outcomes, or late outcomes were detected among the groups. Overall, 19 patients are alive (18 in New York Heart Association functional class I and 1 in New York Heart Association functional class III) at a mean follow-up of 49 months. Two late aortic allograft failures necessitated reoperation. All patients with successful pulmonary autografts had excellent autograft function at a mean follow-up of 68 months. All early survivors with mechanical valved conduits are alive and free of valve-related events (mean follow-up 71 months). Five-year freedoms from valve-related death or event (Kaplan-Meier) were 84% for all patients, 91% for aortic allografts, 78% for pulmonary autografts, and 80% for mechanical valved conduits (no statistically significant group differences by log-rank test). CONCLUSIONS: Replacement of cryopreserved aortic root allografts placed during childhood is safe. Five-year pulmonary autograft durability is excellent, although the risk of early failure may be increased. Differences in 5-year conduit longevity were not detectable.

Adolescent↗