Publications by authors named "Zhen Hao Ang"

7 Publications

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Accuracy of pelvic magnetic resonance imaging in local staging for rectal cancer: a single local health district, real world experience.

ANZ J Surg 2021 01 28;91(1-2):111-116. Epub 2020 Dec 28.

Department of Colorectal Surgery, Wollongong Hospital, Wollongong, New South Wales, Australia.

Background: Neoadjuvant chemoradiotherapy plays a key role in reducing local recurrence rates for locally advanced rectal cancer. Pelvic magnetic resonance imaging (pMRI) is the gold standard for local clinical staging which allows clinicians to decide the treatment patients receive. A more advanced tumour or the presence of high-risk features on pMRI mean that neoadjuvant therapy will be offered to these patients. Understanding the accuracy of pMRI in local staging for rectal cancer is therefore crucial.

Methods: A retrospective cohort analysis of the accuracy of pMRI staging in a subgroup of patients who had primary rectal cancer surgery without neoadjuvant therapy was performed. Specificity and sensitivity for T-staging, N-staging and presence of high-risk features (threatened circumferential resection margin and extramural venous invasion) were calculated. Patients who had previous pelvic surgery, previous pelvic radiotherapy and previous surgery for continence were excluded.

Results: A total of 114 patients were included in the analysis. MRI accurately predicts T-stage in 56.6% and N-stage in 55.8%. Prediction of extramural disease was accurate in 51%. A negative circumferential resection margin was accurately predicted in 98.6% of patients. Overall adherence to reporting proforma was 15.8%.

Conclusion: Overall, this study provided valuable information about the clinical staging of patients with rectal cancer who are at an early stage within a large regional catchment area in Australia with pMRI. These results allow us to assess the accuracy of our local staging with ramifications to the clinical decisions being made in the context of the more recent trials which questioned the need for neoadjuvant chemo-radiotherapy in all node positive patients.
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http://dx.doi.org/10.1111/ans.16509DOI Listing
January 2021

Should cardiac surgery be delayed in patients with uncorrected hypothyroidism?

Interact Cardiovasc Thorac Surg 2020 11;31(5):618-621

Department of Cardiothoracic Surgery, Prince of Wales Hospital, Randwick, NSW, Australia.

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: 'should cardiac surgery be delayed in patients with uncorrected hypothyroidism?' A total of 1412 papers were found using the reported search, of which 7 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. There was limited high-quality evidence with the majority of the studies being retrospective. One propensity-matched analysis and 6 cohort studies provided the evidence that there was no significant difference in the rate of major adverse cardiac events including mortality based on thyroid status. However, hypothyroidism and subclinical hypothyroidism were associated with higher rates of postoperative atrial fibrillation. Based on the available evidence, we conclude that cardiac surgery should not be delayed to allow achievement of euthyroid status.
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http://dx.doi.org/10.1093/icvts/ivaa172DOI Listing
November 2020

Comparison of novel oral anticoagulants versus warfarin for post-operative atrial fibrillation after coronary artery bypass grafting.

Ann Med Surg (Lond) 2020 Oct 8;58:130-133. Epub 2020 Sep 8.

Department of Cardiothoracic Surgery, Prince of Wales Hospital, Sydney, Australia.

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Does the use of Novel Oral Anticoagulants (NOACs) result in more complications than Warfarin for treatment of post-operative atrial fibrillation (AF) following coronary artery bypass grafting (CABG)?' Altogether more than 93 papers were found using the reported search with 4 studies representing the best evidence to answer the clinical question, including 1 randomised trial and 3 retrospective case-control studies. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. Timing for initiation of anticoagulation was similar across the studies, with both demonstrating longer hospital stays and greater time to reach therapeutic anticoagulation in the warfarin cohort. Three studies reported similar safety between the two groups. One study revealed significantly more invasive interventions for pleural or pericardial effusions in the NOAC group, whilst in contrast another study demonstrated a higher rate of major bleeding in the warfarin cohort. Cost-analysis revealed that NOACs were overall more cost-effective compared to warfarin despite the higher cost for the medication itself. In conclusion, the use of NOACs after CABG for post-operative AF can be used as an alternative to warfarin, however, one should remain vigilant for possible pericardial or pleural effusions which may require reintervention. Further dedicated research and larger appropriately powered randomised control trials are needed to confirm the safety of NOACs in post-cardiac surgery patients.
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http://dx.doi.org/10.1016/j.amsu.2020.09.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7493037PMC
October 2020

In patients undergoing dialysis who require a valve replacement is a bioprosthetic valve superior to a mechanical prosthesis in terms of long-term survival and morbidity?

Interact Cardiovasc Thorac Surg 2020 08;31(2):174-178

Department of Cardiothoracic Surgery, Prince of Wales Hospital, Randwick, NSW, Australia.

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'In [dialysis patients undergoing a valve replacement] is [a bioprosthetic valve superior to a mechanical prosthesis] for [long-term survival and morbidity]'. Altogether more than 501 papers were found using the reported search, of which five represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. There was limited high-quality evidence with all studies being retrospective. One meta-analysis and four cohort studies provided the evidence that there was no significant difference in long-term survival based on prosthesis type. However, the majority of studies demonstrated a significantly higher rate of valve-related complications including bleeding and thromboembolism, and readmission to hospital in the mechanical valve prosthesis group, likely related to the requirement for long-term anticoagulation. We conclude that overall long-term survival in dialysis-dependent patients is poor. While prosthesis type does not play a significant contributing role to long-term survival, bioprosthetic valves were associated with significantly fewer valve-related complications. Based on the available evidence, a bioprosthetic valve may be more suitable in this high-risk group of patients as it may avoid the complications associated with long-term anticoagulation without any reduction in long-term survival.
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http://dx.doi.org/10.1093/icvts/ivaa084DOI Listing
August 2020

How to do a handsewn reversal of ileostomy: a systematic technique for new surgical trainees.

ANZ J Surg 2020 09 21;90(9):1762-1763. Epub 2020 Jun 21.

Department of Colorectal Surgery, Wollongong Hospital, Wollongong, New South Wales, Australia.

A straightforward, systematic and reproducible framework for junior registrars to adopt when learning the handsewn ileostomy closure technique.
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http://dx.doi.org/10.1111/ans.16062DOI Listing
September 2020

General Surgeons Australia's 12-point plan for emergency general surgery.

ANZ J Surg 2019 07 7;89(7-8):809-814. Epub 2019 Jul 7.

Department of General Surgery, Prince of Wales Hospital, Sydney, New South Wales, Australia.

In the last decade, emergency general surgery (EGS) in Australia and New Zealand has seen a transition from the traditional on-call system to the acute surgical unit (ASU) model. The importance and growing demand for EGS has resulted in the implementation of the General Surgeons Australia's 12-point plan for emergency surgery. Since its release, the 12-point plan has been used as a benchmark of a well-functioning ASU, both locally and abroad. This study aims to provide a descriptive review on the relevance of the 12-point plan to the ASU model and review the current evidence to support this framework. The review concludes that the establishment of the ASU model has met the aims set out by the Royal Australasian College of Surgeons for EGS. The 12-point plan is relevant and has good evidence to support its framework.
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http://dx.doi.org/10.1111/ans.15327DOI Listing
July 2019

Idiopathic sclerosing encapsulating peritonitis: a rare surgical presentation.

ANZ J Surg 2019 Jun 8;89(6):E274-E275. Epub 2018 Jan 8.

Prince of Wales Clinical School, The University of New South Wales, Sydney, New South Wales, Australia.

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http://dx.doi.org/10.1111/ans.14347DOI Listing
June 2019