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Dive into the research topics where S. Lo is active.

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Featured researches published by S. Lo.


Catheterization and Cardiovascular Interventions | 2004

Patient tolerance and resource utilization associated with an arterial closure versus an external compression device after percutaneous coronary intervention

C. Juergens; Dominic Y. Leung; John A. Crozier; Adelina M. Wong; Jacqui T.C. Robinson; S. Lo; Hashim Kachwalla; A. Hopkins

We assessed patient tolerance and resource utilization of using the AngioSeal closure device versus assisted manual compression using the Femostop device after percutaneous coronary intervention (PCI). Patients undergoing PCI with clean arterial access and no procedural hematoma were randomized to receive the AngioSeal or Femostop device to achieve femoral arterial hemostasis. Times from procedure end to removal from angiography table, hemostasis, ambulation, and hospital discharge were recorded. Bedside nursing/medical officer care time, vascular complications, and disposable use were also documented. Patient comfort was assessed using Present Pain Intensity and Visual Analogue scales at baseline, 4 hr, 8 hr, and the morning after the procedure. One hundred twenty‐two patients were enrolled (62 AngioSeal, 60 Femostop). Patients in the AngioSeal group took longer to be removed from the angiography table (11 ± 4 vs. 9 ± 3 min; P = 0.002) compared with the Femostop group. Time to hemostasis (0.4 ± 1.1 vs. 6.4 ± 1.7 hr; P < 0.001) and ambulation (17 ± 8 vs. 22 ± 13 hr; P = 0.004) were less in the AngioSeal group, although time to discharge was not different. Nursing and medical officer time was no different. Disposables including device cost were higher in the AngioSeal group (


Journal of The American Society of Echocardiography | 2008

Left ventricular longitudinal and radial synchrony and their determinants in healthy subjects

Arnold C.T. Ng; Da T. Tran; Mark Newman; Christine Allman; Jane Vidaic; S. Lo; A. Hopkins; Dominic Y. Leung

209 ± 13 vs.


Journal of Cardiovascular Electrophysiology | 1999

Review: Clinical aspects of vascular remodeling.

Niall A. Herity; Michael R. Ward; S. Lo; Alan C. Yeung

53 ± 9; P < 0.001). On a Visual Analogue scale, patients reported more pain at 4 hr (P < 0.001) and 8 hr (P < 0.001) in the Femostop group. The worst amount of pain at any time point was also more severe in the Femostop group (P < 0.001). Similar results were found on a Present Pain Intensity scale of pain. There were no differences in ultrasound‐determined vascular complications (two each). Femoral access site closure using the AngioSeal device resulted in a small delay in leaving the angiography suite and a higher disposable cost compared to using the Femostop device. However, patients receiving the AngioSeal were able to ambulate sooner and reported less pain, which may justify the increased costs involved. Catheter Cardiovasc Interv 2004;63:166–170.


Internal Medicine Journal | 2009

Nephrotoxic effects of iodixanol and iopromide in patients with abnormal renal function receiving N‐acetylcysteine and hydration before coronary angiography and intervention: a randomized trial

C. Juergens; J. P. Winter; P. Nguyen‐Do; S. Lo; John K. French; H. Hallani; C. Fernandes; N. Jepson; Dominic Y. Leung

OBJECTIVE The reference values and impact of physiologic variables on echocardiographic quantification of left ventricular (LV) synchrony in a large series of healthy persons are unknown. This study prospectively investigated the impact of age, gender, and other physiologic parameters on LV longitudinal and radial synchrony. METHODS LV longitudinal systolic and diastolic synchrony using tissue Doppler imaging were measured as the standard deviation of times to 12 regional peak myocardial systolic Sm (SDTs) and early diastolic Em (SDTe) velocities in 122 healthy volunteers (age 19-68 years, 64 men). By using 2-dimensional speckle tracking, radial synchrony was measured as the standard deviation of times to 6 regional peak strain (SDTrepsilon) in the short-axis papillary muscle level. Longitudinal systolic synchrony was also measured as the standard deviation of times to 12 regional peak strain (SDTlepsilon). RESULTS The mean QRS duration and LV ejection fraction were 87 +/- 12 msec and 61% +/- 5.5%, respectively. The mean SDTs and SDTe were 37.1 +/- 17.4 msec and 17.3 +/- 6.7 msec, respectively. Gender and the mean Sm velocity from the 6 basal LV segments were independent predictors of SDTs, whereas the isovolumic relaxation time and mean Em velocity independently predicted SDTe. The mean SDTrepsilon was 19.2 +/- 14.6 msec. SDTrepsilon did not correlate with any clinical or echocardiographic parameters. The mean SDTlepsilon was 40.4 +/- 11.8 msec. Isovolumic relaxation time, pulmonary S/D ratio, and mean Sm independently predicted SDTlepsilon. There was no correlation between LV longitudinal and radial synchrony. Intraobserver and interobserver variability analyses showed the highest correlation for SDTs compared with SDTrepsilon and SDTlepsilon. CONCLUSION This study establishes normal reference ranges for LV systolic and diastolic synchrony measured with tissue Doppler velocity-based and 2-dimensional speckle tracking-based methods in a large group of healthy subjects of both genders across a wide age group. SDTs is gender specific and dependent on global LV systolic function, whereas SDTe is dependent on global LV diastolic function. Two-dimensional speckle-derived radial synchrony is independent of any clinical and echocardiographic variables but has higher intraobserver and interobserver variability compared with SDTs. LV longitudinal synchrony does not correlate with radial synchrony.


Journal of the American College of Cardiology | 2003

Effect of a change in gender on coronary arterial size: a longitudinal intravascular ultrasound study in transplanted hearts.

Niall A. Herity; S. Lo; David P. Lee; Michael R. Ward; Steven D Filardo; Paul G. Yock; Peter J. Fitzgerald; Sharon A. Hunt; Alan C. Yeung

Clinical Aspects of Vascular Remodeling. Vascular remodeling represents a spectrum of structural changes whereby the vascular wall responds to changes in its hemodynamic environment. Such changes may be classified as vessel enlargement (outward remodeling), diminution (inward remodeling), alternatively as adaptive (compensatory, appropriate to the hemodynamic stimulus), or maladaptive (dysfunctional, inappropriate). The direction and scale of remodeling are coordinated by endothelial production of growth factors, proteases, and cellular adhesion molecules in response to sensed changes in blood flow. In early atherosclerosis, outward remodeling preserves lumen size. Although protective in the long‐term, the matrix degradation involved in this process may predispose atherosclerotic plaques to rupture, hence increasing the risks of acute coronary syndromes. Inward remodeling also occurs in advanced atherosclerotic lesions, whereby the vessel shrinks rather than enlarging, exacerbating rather than ameliorating stenosis. In transplant coronary artery disease, early inward remodeling may he a more important component of vessel stenosis than intimal thickening, while inappropriate inward remodeling appears to he as least as important as excessive intimal growth in the development of restenosis after angioplasty. Increased awareness of vascular remodeling, and in particular its malaptive forms, may provide new therapeutic insights for the future.


Catheterization and Cardiovascular Interventions | 2000

Selective regional myocardial infiltration by the percutaneous coronary venous route: A novel technique for local drug delivery

Niall A. Herity; S. Lo; Frederick Oei; David P. Lee; Michael R. Ward; Steven D Filardo; Ali Hassan; Takeshi Suzuki; Mehrdad Rezaee; Andrew J. Carter; Paul G. Yock; Alan C. Yeung; Peter J. Fitzgerald

Background:  The use of contrast agents during coronary intervention can result in nephropathy, particularly in patients with renal dysfunction. We aimed to determine whether the use of iso‐osmolar iodixanol is less nephrotoxic than that of low‐osmolar iopromide when patients are adequately prehydrated and have received N‐acetylcysteine.


International Journal of Cardiology | 2015

Antithrombotic treatment for stroke prevention in atrial fibrillation: The Asian agenda

Chen-Huan Chen; Mien Cheng Chen; Harry Gibbs; Sun U. Kwon; S. Lo; Young Keun On; Azhari Rosman; Nijasri C. Suwanwela; Ru San Tan; Louie S. Tirador; Andreas Zirlik

OBJECTIVES We sought to document whether a physiologic change in gender has any effect on coronary arterial size. BACKGROUND The coronary arteries are smaller in women, even after correction for body surface area (BSA). These differences may contribute to adverse clinical outcomes after coronary artery bypass graft surgery and myocardial infarction in women. In male and female transsexuals, pharmacologic doses of estrogens and androgens significantly influence vascular diameter. Thus, gender differences in the coronary vasculature may be a reflection of the hormonal environment. METHODS In 86 patients who had undergone orthotopic heart transplantation, serial intravascular ultrasound studies of the proximal left anterior descending coronary artery (LAD) were analyzed. Changes in vessel area (VA) over the first or second post-transplant year were recorded, and comparisons were made between donor hearts that were transplanted in a patient of the same gender and those that were transplanted in a patient of the opposite gender. RESULTS Vessel area of the proximal LAD increased over time in all patient groups. In hearts transplanted within the same gender and in male donor hearts transplanted to female recipients, the change was small and not significant. However, in hearts transplanted from female donors to male recipients, there was a substantial and highly significant increase in LAD VA (median 16.13 to 17.88 mm(2); p = 0.01). This increase was not explained by confounding due to changes in BSA or left ventricular wall thickness. CONCLUSIONS This pattern of arterial remodeling early after heart transplantation supports a link between host gender and coronary arterial size.


Journal of the American Heart Association | 2014

Varying Definitions for Periprocedural Myocardial Infarction Alter Event Rates and Prognostic Implications

H. Idris; S. Lo; I. Shugman; Y. Saad; A. Hopkins; C. Mussap; Dominic Y. Leung; Liza Thomas; C. Juergens; John K. French

Recent advances in the treatment of heart disease, in particular cardiovascular gene therapy and therapeutic angiogenesis, highlight the need for efficient and practical local delivery methods for the heart. We assessed the feasibility of percutaneous selective coronary venous cannulation and injection as a novel approach to local myocardial drug delivery. In anesthetized swine, the coronary sinus was cannulated percutaneously and a balloon‐tipped catheter advanced to the anterior interventricular vein (AIV) or middle cardiac vein (MCV). During balloon occlusion, venous injection of radiographic contrast caused regional infiltration of targeted myocardial regions. Complete AIV occlusion had no impact on LAD flow parameters. Videodensitometric analysis following venous injection showed that radiographic contrast persisted for at least 30 min. Selective regional myocardial infiltration is feasible by this approach, targeting selected myocardial beds, including the apex, anterior wall, septum, and inferoposterior wall. This novel technique has potential application for local myocardial drug or growth factor delivery. Cathet. Cardiovasc. Intervent. 51:358–363, 2000.


American Journal of Cardiology | 2000

Acute Myocardial Infarction and Vascular Remodeling

Steven D Filardo; Severin P. Schwarzacher; S. Lo; Niall A. Herity; David P. Lee; Heike Huegel; William L Mullen; Peter J. Fitzgerald; Michael R. Ward; Alan C. Yeung

Atrial fibrillation (AF) is the most common heart arrhythmia. Untreated AF incurs a considerable burden of stroke and associated healthcare costs. Asians have AF risk factors similar to Caucasians and a similarly increased risk of AF-related stroke; however, with a vast and rapidly ageing population, Asia bears a disproportionately large disease burden. Urgent action is warranted to avert this potential health crisis. Antithrombotic therapy with oral anticoagulants is the most effective means of preventing stroke in AF and is a particular priority in Asia given the increasing disease burden. However, AF in Asia remains undertreated. Conventional oral anticoagulation with warfarin is problematic in Asia due to suboptimal control and a propensity among Asians to warfarin-induced intracranial haemorrhage. Partly due to concerns about intracranial haemorrhage, there are considerable gaps between AF treatment guidelines and clinical practice in Asia, in particular overuse of antiplatelet agents and underuse of anticoagulants. Compared with warfarin, new direct thrombin inhibitors and Factor Xa inhibitors are non-inferior in preventing stroke and significantly reduce the risk of life-threatening bleeding, particularly intracranial bleeding. These agents may therefore provide an appropriate alternative to warfarin in Asian patients. There is considerable scope to improve stroke prevention in AF in Asia. Key priorities include: early detection of AF and identification of asymptomatic patients; assessment of stroke and bleeding risk for all AF patients; evidence-based pharmacotherapy with direct-acting oral anticoagulant agents or vitamin K antagonists for AF patients at risk of stroke; controlling hypertension; and awareness-raising, education and outreach among both physicians and patients.


Atherosclerosis | 2001

The influence of plaque orientation (pericardial or myocardial) on coronary arterial remodeling.

Michael R. Ward; Allen Jeremias; Kiyoshi Hibi; Niall A. Herity; S. Lo; Steven D Filardo; David P. Lee; Peter J. Fitzgerald; Alan C. Yeung

Background Periprocedural myocardial infarction (PMI) has had several definitions in the last decade, including the Society for Cardiovascular Angiography and Interventions (SCAI) definition, that requires marked biomarker elevations congruent with surgical PMI criteria. Methods and Results The aim of this study was to examine the definition‐based frequencies of PMI and whether they influenced the reported association between PMI and increased rates of late death/ myocardial infarction (MI). We studied 742 patients; 492 (66%) had normal troponin T (TnT) levels and 250 (34%) had elevated, but stable or falling, TnT levels. PMI, using the 2007 and the 2012 universal definition, occurred in 172 (23.2%) and in 99 (13.3%) patients, respectively, whereas 19 (2.6%) met the SCAI PMI definition (P<0.0001). Among patients with PMI using the 2012 definition, occlusion of a side branch ≤1 mm occurred in 48 patients (48.5%) and was the most common angiographic finding for PMI. The rates of death/MI at 2 years in patients with, compared to those without, PMI was 14.7% versus 10.1% (P=0.087) based on the 2007 definition, 16.9% versus 10.3% (P=0.059) based on the 2012 definition, and 29.4% versus 10.7% (P=0.015) based on the SCAI definition. Conclusion In this study, PMI, according to the SCAI definition, was associated with more‐frequent late death/MI, with ≈20% of all patients, who had PMI using the 2007 universal MI definition, not having SCAI‐defined PMI. Categorizing these latter patients as SCAI‐defined no PMI did not alter the rate of death/MI among no‐PMI patients.

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C. Juergens

University of New South Wales

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Dominic Y. Leung

University of New South Wales

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Liza Thomas

University of New South Wales

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I. Shugman

University of New South Wales

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J. Xu

Liverpool Hospital

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