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Biomedical subjects

R W Frater

Publications and source records attributed to R W Frater.

At least 19 recordsLinked to original sources
PubMed2001

Mitral ring annuloplasty: an incomplete correction of functional mitral regurgitation associated with left ventricular remodeling.

Functional mitral regurgitation (FMR) occurs commonly in patients undergoing left ventricular (LV) remodeling. It is ubiquitous in patients referred to cardiac transplantation for LV systolic dysfunction and predicts a poor prognosis. The LV remodeling that is responsible for FMR is well understood and involves regional LV dysfunction Mitral annular dilatation is present in patients with idiopathic dilated cardiomyopathy but most often absent in patients with ischemic cardiomyopathy. Nonrandomized observations indicate that implantation of a mitral undersized flexible mitral ring reduces the amount of FMR, reverses LV remodeling, and improves symptoms in patients with end-stage cardiomyopathy and severe FMR. Whether a surgical procedure that does not correct the major LV alterations leading to FMR can have long-lasting effects on the amount of FMR and the reversal of LV remodeling remains to be demonstrated in randomized trials.

Heart Valve Prosthesis Implantation↗
PubMed2001

Age and valve size effect on the long-term durability of the Carpentier-Edwards aortic pericardial bioprosthesis.

BACKGROUND: Bioprosthesis durability decreases with time and younger age. However, the time-scale and determinants of durability of the aortic Carpentier-Edwards stented bovine pericardial prosthesis are incompletely characterized. METHODS: Between September 1981 and January 1984, 267 patients underwent implantation of the pericardial aortic prosthesis at four centers. Mean age at implant was 65 +/- 12 years (range 21 to 86 years). Follow-up averaged 12 +/- 4.5 years. The primary end point was explant for structural valve dysfunction (SVD), which was analyzed multivariably in the context of death as a competing risk. RESULTS: Freedom from explant due to SVD was 99%, 94%, and 77% at 5, 10, and 15 years. Risk of SVD increased exponentially with time and younger age (p = 0.0001) at implantation; an increased risk of small valve size was not reliably demonstrated (p = 0.1). Considering the competing risk of death, patients aged 65 years or older had a less than 10% chance of explant for SVD by 15 years. CONCLUSIONS: Durability of this stented pericardial aortic bioprosthesis is excellent and justifies its use in patients aged 65 or older.

Actuarial Analysis↗
PubMed2000

Cardiac surgery and the human immunodeficiency virus.

Since the first deliberate open heart operation was performed on a patient known to be carrying HIV, much has been learned. The fear that cardiopulmonary bypass might cause acceleration of the disease has not been borne out. Patients infected with HIV have shown considerable tolerance to major cardiac and pulmonary surgery. Indeed, the extraordinary fruits of a massive research effort have made it reasonable to perform elective surgery and to offer major surgery to patients with the full-blown syndrome of AIDS. The concern that the operators would be exposed to significant risk of acquiring the infection during surgery has proved to be unfounded. This has been in part due to the widespread adoption of universal precautions against the passage of microorganisms from patient to operator. However, there remain surgeons who ignore these precautions. The price they pay is the risk of acquiring hepatitis, which is far more easily transmitted than AIDS and may be fatal.

Attitude of Health Personnel↗
PubMed1999

Contraction-relaxation coupling: determination of the onset of diastole.

Left ventricular relaxation is dependent on afterload conditions during systole. An abrupt increase in afterload while the ventricle is actively contracting prolongs the duration of systole. An increase in afterload during ventricular relaxation shortens the duration of systole. Therefore, we hypothesized that the point during systole when an abrupt increase in afterload had no effect on the duration of systole represented the onset of ventricular relaxation. To determine when this point occurs, we performed aortic occlusions progressively throughout the duration of systole in six dogs. We determined the change in systolic time (t(sys)) after an intervention normalized to t(sys) of a control beat (t(sys,i)/t(sys, c)) as a function of systolic occlusion time as a percentage of total systolic time (t(occ)/t(sys,c)), where t(sys) is the duration from time of left ventricular end-diastolic pressure to the time of minimum first derivative of left ventricular pressure. Our results show the onset of left ventricular relaxation during normal ejection occurs at 34 +/- 3% of systolic time and approximately 16% after the onset of ejection. Thus the beginning of relaxation occurs soon after the beginning of ejection, suggesting that relaxation is modulated by variable loading conditions during ejection, significantly before what has been conventionally been assumed to be the beginning of ventricular relaxation.

Animals↗
PubMed1998

An unusual presentation of metastatic colon cancer to the lung.

A 75-year-old man with a history of resected colon carcinoma presented to his primary care physician because of a new onset of coughing. The patient had expectorated a small piece of solid tissue; pathologic examination of the tissue found it to be consistent with metastatic colon adenocarcinoma. After further work-up, a right upper lobectomy was performed. The surgical specimen removed during the lobectomy showed a tumor that was histologically identical to the patient's prior colonic primary tumor.

Adenocarcinoma↗
PubMed1998

Long-term durability and patient functional status of the Carpentier-Edwards Perimount pericardial bioprosthesis in the aortic position.

BACKGROUND AND AIMS OF THE STUDY: The study aim was to examine the long-term durability of the aortic Carpentier-Edwards Perimount pericardial bioprosthesis using actuarial and actual analyses. METHODS: A total of 267 patients were implanted at four centers between September 1981 and December 1983. Of these patients, 171 (64%) were males and 96 (36%) females; mean age at implant was 64.9+/-11.8 years (range: 21 to 86 years). Patients have been followed for 9.1+/-4.2 years (total 2335.7 patient-years). Long-term echocardiography data are presented. RESULTS: The total operative (<30 days postoperative) mortality rate was 4.9%; of this, 0.4% was valve-related. The total late (> or = 30 days postoperative) mortality rate was 6.2%/pt-yr and included a valve-related mortality rate of 1.6%/pt-yr. Complications of thromboembolism, thrombosis and bleeding showed linearized rates of 1.6%/pt-yr and 0.4%/pt-yr, respectively. Valve dysfunction resulted in an explant rate of 0.9%/pt-yr and an associated mortality rate of 0.1%/pt-yr. At 14 years post implant, actuarial freedom from overall and valve-related death was 39.3% and 78.8%, respectively. Actuarial and actual freedom from valve dysfunction was 70.4% and 81.7%. Actuarial freedom from valve explant as a result of dysfunction was 85.1% in all patients; explant in patients aged < or = 65 years at implant was less (76.1%) than in patients aged >65 years (96.3%). CONCLUSION: The high actuarial and actual freedom from explant due to structural valve dysfunction supports the long-term durability of this pericardial bioprosthesis and justifies its clinical use in patients older than 65 years at implant.

Adult↗
PubMed1997

MRI in the evaluation and management of a newborn infant with cardiac rhabdomyoma.

A newborn infant presented with a life-threatening cardiac arrhythmia. Echocardiography showed a large cardiac mass growing exophytically in the region of the left atrial appendage extending along the left ventricular wall but showed no clear tissue plane between the mass and the left ventricular wall. Based on the echocardiogram, surgical resection might damage the left ventricular wall. Magnetic resonance imaging demonstrated a clear plane of demarcation, making surgical resection a viable life-saving option.

Heart Neoplasms↗