Biomedical subjects

H Welch

Publications and source records attributed to H Welch.

4 recordsLinked to original sources

PubMed1992

Routine postendarterectomy duplex surveillance: does it prevent late stroke?

Our recent finding that less than 50% of late postendarterectomy strokes are related to recurrent carotid stenosis led us to question the utility of routine postendarterectomy duplex surveillance (RpCEADS) in the prevention of late stroke. To evaluate our RpCEADS program, we reviewed our postoperative duplex studies and correlated their results with clinical data. A total of 1053 postendarterectomy scans was carried out on 348 carotid arteries (258 patients) (3.0 +/- 0.1 studies/artery) during an average follow-up of 52.6 (+/- 2.3) months. Less than 50% of recurrent carotid stenosis was documented throughout follow-up in 292 (83.9%) of 348 arteries. Recurrent carotid stenosis of greater than 50% or occlusion of either the common or internal carotid artery was noted in the remaining 56 arteries (16.1%). Of the 56 duplex-detected recurrent stenoses, only two (3.6%) resulted directly in an unheralded stroke, whereas eight (14.3%) underwent prophylactic reoperation, eight (14.3%) resulted in transient ischemia requiring reoperation, eight (14.3%) occluded without causing stroke, and 29 (51.8%) remained asymptomatic and did not progress to occlusion. Assuming that each of our eight patients who underwent prophylactic reoperation would have had a stroke if operation had not been carried out and our two unheralded strokes could have been prevented with more rigorous follow-up, RpCEADS might have prevented late stroke related to 10 (2.9%) of 348 arteries in 10 (3.9%) of 258 patients after surgery. All other cases of duplex-detected recurrent carotid stenosis or occlusion were asymptomatic or manifest by transient cerebral ischemia. Therefore RpCEADS cannot be justified as a means of preventing late strokes related to recurrent stenosis.

Carotid Stenosis↗

PubMed1986

Complications of carotid endarterectomy. A military hospital experience.

The Naval Hospital Oakland (NHO) carotid study is a review of the morbidity and mortality of an 8-year experience of 201 consecutive carotid endarterectomies (164 patients). Arteriographic findings, risk factors, method of patient management, and all major and minor complications are discussed. Patient groups are categorized by indication for surgery and by the Mayo Clinic classification of Sundt. A credentialed attending surgeon assisted a senior general surgery resident (81.6%) or performed the operation himself (18.4%). Resident and staff adverse occurrences are compared. Complications in the NHO study were present in 35.8 per cent of cases (8.9% major). Elimination of myocardial infarction and transient ischemic attacks reduced this to 4 per cent. The experience is compared to one in a university setting, a Veteran Administration study, community hospital studies, and a study performed in another major military medical center.

Adult↗

PubMed1979

Failure of carotid stump pressures. Its incidence as a predictor for a temporary shunt during carotid endarterectomy.

A total of 289 carotid endarterectomies were performed in 204 patients. A decision to place a temporary shunt during carotid endarterectomy in this series was made entirely on the basis of intraoperative EEG monitoring. Retrospectively, the correlation between stump pressures and the results of intraoperative EEG monitoring in each case was determined. Evidence of ischemia developed in 6% of the total series on intraoperative EEG monitoring despite a stump pressure of greater than 50 mm Hg. The degree of disagreement between stump pressure and EEG varied according to clinical category in this series. In those endarterectomies performed for completed stroke, all cases requiring shunting had stump pressures less than 50 mm Hg. In those cases performed for symptoms of vertebral basilar insufficiency, however, 77% of the cases requiring an intraoperative shunt had stump pressures greater than 50 mm Hg. A review of the complication rate in the various study groups indicates that the use of intraoperative EEG is a safe indicator of cerebral ischemia during carotid endarterectomy regardless of stump pressure.

Blood Pressure↗

PubMedDate not supplied

Reducing the variability in durability of heart valve bioprostheses. Key factor for future improvement.

Two observations concerning the Meadox unicusp bovine pericardial valve were presented. First, calcification has not been a major problem because of the relatively short implant durations (less than 5 years). The second observation was that thromboembolism was found to be practically nonexistent. The third observation was that the leaflets of certain valves that had been removed showed leaflet stretching, which resulted in excess stress in certain loci of the leaflet. The studies reported here showed that the bovine pericardial sac was distensible to various degrees. Strips from various sections of pericardium had a large spectrum of strain (5-45%), at very small stress levels (less than or equal to 4 g/mm2). Further, within any section the material was anisotropic, with strain differences of 25%. Finally, histologic studies of clinical grade Ionescu-Shiley bovine pericardial valves showed marked discrepancies in structure and staining characteristics, further documenting that this material is not homogeneous. New methods of tissue selection are mandatory and have been designed to improve uniformity and ultimately reduce the viability in performance in the clinical setting. This method can be applied to all pericardial valves.

Animals↗