Browsing by Author "Van Wyk, Jacques"

Now showing 1 - 6 of 6
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    7-Year experience of transcatheter aortic valve implants (TAVI) in a Western Cape private healthcare setting
    (South African Heart Association, 2019) Weich, Hellmuth; Liebenberg, Jacques; Van Wyk, Jacques; Vivier, Rocco; Barnard, Barry; Abelson, Mark; Phillips, Andre; Mabin, Tom
    Introduction: We describe the largest South African transcatheter aortic valve implantation (TAVI) outcome report of a single team in the Western Cape, over a 7-year period from 2009 - 2016. Methods: All patients who received TAVI at Mediclinic Vergelegen and Mediclinic Panorama were prospectively entered into a database. A total of 244 implants (61 CoreValve and 183 Edwards valves) were performed. Results: Patients were high risk with a mean STS score of 7.89 (standard deviation (SD) 5.7) and mean logistic EuroSCORE of 26.5 (SD 12.5). There was a trend toward lower risk over time. Procedures were initially performed mainly via a transapical approach, but this changed to mostly transfemoral with the introduction of smaller delivery systems. Procedural success rate was 91.8% for CoreValve and 88.5% for Edwards cases. Mean length of hospital stay following TAVI was 9 days initially, but this declined to 4 days for the latter part of our experience. One year mortality was 19% and one year stroke rate was 10%. Conclusion: Despite the limitations of a study of this nature, our group could document outcomes similar to international studies, with improvements over time and illustrating successful cooperation between different hospitals to expand exposure and experience in a resource-constrained environment.
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    First case of trans apical implantation of an aortic valve in a patient with dextrocardia
    (BioMed Central, 2012-03) Weich, Hellmuth S.; Van Wyk, Jacques; Van Zyl, Wynand; Vivier, Rocco; Phillips, Andre; Mabin, Thomas
    Abstract We describe the clinical presentation and implantation procedure of the first transcatheter aortic valve implantation described in a patient with dextrocardia.
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    How to automatically detect calls from cetaceans and fish without large-scale training data
    (Stellenbosch : Stellenbosch University, 2024-03) Van Wyk, Jacques; Versfeld, Jaco; Du Preez, Johan; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: Passive acoustic monitoring has become pivotal in the acquisition of vocalisations produced by marine wildlife, however, there is a need for suitable detection methods that can segment these vocalisations from the many hours of noise present in the retrieved audio recordings. Automatic detection methods can aid in this, labelling potential animal calls in bioacoustic recordings faster than manual annotation. One problem modern automatic detection methods suffer from, particularly deep learning methods, is overfitting due to small training sets. This calls for detection methods that can quickly and accurately detect bioacoustic vocalisations without the need for copious amounts of training data. Such detection methods are proposed here for the automatic detection of cetacean and fish vocalisations in underwater recordings. The first method is a silence detector based on a temporal power calculation that can be used as a pre-processing step to quickly find potential target calls. The harmonic structure of vocalisations is then exploited to aid in their detection. The second method is based on the summation of sound harmonics, with a normalisation scheme that provides robust performance in the presence of wide-band noise. The third method extends this normalisation scheme to spectrogram masking, a faster alternative to spectrogram cross-correlation. After this the use of unsupervised deep learning methods are investigated, in an attempt to determine their ability to detect cetacean vocalisations in the presence of imbalanced data.
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    Malignant peripheral nerve sheath tumours and neurofibromatosis 1 : a case series and recommendations for care
    (AOSIS, 2018-08-20) Burger, Henriette; Bezuidenhout, Heidre; Sher-Locketz, Candice; Baatjes, Karin; Van Wyk, Jacques; Bonthuys, Anita
    Background: The incidence of malignant peripheral nerve sheath tumours (MPNST) in patients with neurofibromatosis 1 (NF1) is significantly higher than that of the general population. NF1-associated MPNST occur at a younger age and carry a worse prognosis than sporadic MPNST. Aim: This case series describes four cases of MPNST in patients with NF1. Setting: The study was performed in a public academic hospital in the Western Cape province of South Africa. Method: Demographics, disease status, histopathology, treatment and outcome data were collected retrospectively from medical charts and through review of histological slides. Results: The median age was 36.5 years. All tumours were > 5 cm at presentation and located on the trunk. One patient presented with metastatic disease. There was a mean delay of 3.5 months from presentation to initiation of treatment. Three patients underwent wide excision, with one receiving adjuvant chemotherapy and radiotherapy. At a median follow-up of 20 months from histological diagnosis only one patient was alive in clinical remission. Two patients had succumbed to progressive disease at 8 and 16 months from diagnosis and one patient with terminal metastatic disease was lost to follow-up. Conclusion: In this series the patients presented with advanced, often unresectable lesions for which single modality therapy was not curative. An adult NF1 health surveillance guideline for resource-constrained environments could lead to early diagnosis and treatment of MPNST and other complications in NF1 patients.
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    The South African SHARE-TAVI registry : incidence and risk factors leading to conduction disturbances requiring permanent pacemaker implantation
    (South African Heart Association, 2021) Du Toit, Rudolf; Doubell, Anton; Abelson, Mark; Hellig, Farrel; Horak, Adie; Mabin, Thomas; Klug, Eric; Schaafsma, Elizabeth; Van Wyk, Jacques; Scherman, Jacques; Ntsekhe, Mpiko; Weich, Hellmuth
    Background: One of the most common complications post transcatheter aortic valve implantation (TAVI) is the development of heart block requiring permanent pacemaker implantation (PPM). The incidence of PPM in international registries ranges from 13% - 17.5%. Methods: The aim of this observational study was to report the PPM rate in the SHARE-TAVI registry and determine the clinical, electrocardiographic and procedural predictors of PPM as well as the effect of PPM on clinical outcomes. Results: Three hundred and fi ve subjects were analysed. The PPM rate was 9%. Third degree atrioventricular block at the time of implant was the most common indication for PPM. Self-expanding valves (PPM rate 14% vs. 6% for balloon-expandable valves, p=0.02) were correlated with the need for PPM. Baseline ECG predictors of PPM were axis deviation, QRS duration and conduction delay, most notably a pre-existing right bundle branch block (OR 15.88, p<0.01). PPM infl uenced functional class at 30 days, but not the need for repeat hospitalisation or mortality at 30-day and 1-year follow-up. Conclusions: A PPM rate lower than that reported in large international registries was found. Predictors of PPM and the infl uence of PPM on outcomes were similar to those reported in the international data.
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    Transcatheter aortic valve in mitral annular calcifi cation (TAV-in-MAC) : a new treatment option for mitral valve replacement in patients with severe annular calcification
    (South African Heart Association, 2019) Weich, Hellmuth; Van Wyk, Jacques; Hofmeyr, Lou; Vogts, Carl
    ENGLISH ABSTRACT: Severe mitral annular calcification is not an uncommon occurrence in the elderly and up to now, this has often precluded surgical replacement of the mitral valve. Initial attempts at percutaneous placement of transcatheter aortic valves in the calcified mitral annulus, has not been very successful due to obstruction of the left ventricular outflow tract. We describe a surgical approach where the anterior mitral valve leaflet was resected and a balloon expandable transcatheter aortic valve then deployed within the calcified annulus. The benefits of this technique over a fully percutaneous approach is discussed.