Papers by Leonard Arnolda
Heart, Lung and Circulation, 2015
BACKGROUND Chronic disease represents a large and growing burden to the health care system worldw... more BACKGROUND Chronic disease represents a large and growing burden to the health care system worldwide. One method of managing this burden is the use of app-based interventions; however attrition, defined as lack of patient use of the intervention, is an issue for these interventions. While many apps have been developed, there is some evidence that they have significant issues with sustained use, with up to 98% of people only using the app for a short time before dropping out and/or dropping use down to the point where the app is no longer effective at helping to manage disease. OBJECTIVE Our objectives are to systematically appraise and perform a meta-analysis on dropout rates in apps for chronic disease and to qualitatively synthesize possible reasons for these dropout rates that could be addressed in future interventions. METHODS MEDLINE (Medical Literature Analysis and Retrieval System Online), PubMed, Cochrane CENTRAL (Central Register of Controlled Trials), and Embase were searc...
Lancet (London, England), Jul 1, 2017
rate monitoring is not a good test of fetal wellbeing. We declare no competing interests.
The Journal of Physiology, 2005
Chronic exercise induces physiological enlargement of the left ventricle ('athlete's heart'), but... more Chronic exercise induces physiological enlargement of the left ventricle ('athlete's heart'), but the effects of current and long-term exercise training on diastolic function have not been investigated. Echocardiography and Doppler imaging were used to assess left ventricular (LV) dimensions and indices of diastolic filling in 22 elite athletes at the end of their 'off-season' (baseline) and, subsequently, following 3 and 6 months of training. Twelve matched controls were also studied at baseline, 3 and 6 months. Compared to controls at baseline, athletes exhibited significantly higher LV mass (235.7 ± 7.1 g versus 178.1 ± 14.5 g, P < 0.01) and reduced flow propagation velocity (V P : 50.21 ± 1.7 versus 72.2 ± 3.6 cm s −1 , P < 0.01), a measure of diastolic function. Three months of training further increased LV mass in athletes (253.2 ± 7.1 g; P < 0.01 versus baseline), and significantly increased their V P (66.7 ± 2.5 cm s −1 ; P < 0.05 versus baseline). These trends for increased mass and diastolic filling persisted following 6 months of training (LV mass 249.0 ± 8.7 g P < 0.05 versus baseline; V P 75.7 ± 3.0 cm s −1 ; P < 0.01 versus baseline, and P = 0.01 versus 3 months). This study suggests that following a period of relative inactivity the rate of ventricular relaxation during early diastole may be slowed in athletes who exhibit ventricular hypertrophy, whilst resumption of training increases the speed of ventricular relaxation in the presence of further hypertrophy of the left ventricle.
Cardiovascular Ultrasound, 2007
Background: Carotid intima-media thickness (CIMT) measured by B-mode ultrasonography is a marker ... more Background: Carotid intima-media thickness (CIMT) measured by B-mode ultrasonography is a marker of atherosclerosis and is commonly used as an outcome in intervention trials. We have developed DICOM-based software that measures CIMT rapidly on multiple end-diastolic image frames. The aims of this study were to compare the performance of our new software with older bitmap-based CIMT measurement software and to determine whether a tenfold increase in the number of measurements used to calculate mean CIMT would improve reproducibility. Methods: Two independent sonographers recorded replicate carotid scans in thirty volunteers and two blinded observers measured CIMT off-line using the new DICOM-based software and older bitmap-based software. A Bland-Altman plot was used to compare CIMT results from the two software programs and t-tests were used to compare analysis times. F-tests were used to compare the coefficients of variation (CVs) from a standard six-frame measurement protocol with CVs from a sixty-frame measurement protocol. Ordinary least products (OLP) regression was used to test for sonographer and observer biases. Results: The new DICOM-based software was much faster than older bitmap-based software (average measurement time for one scan 3.4 ± 0.6 minutes versus 8.4 ± 1.8 minutes, p < 0.0001) but CIMT measurements were larger than those made using the alternative software (+0.02 mm, 95%CI 0.01-0.03 mm). The sixty-frame measurement protocol had worse reproducibility than the six-frame protocol (inter-observer CV 5.1% vs 3.5%, p = 0.004) and inter and intraobserver biases were more pronounced in the sixty-frame than the six-frame results. Conclusion: While the use of DICOM-based software significantly reduced analysis time, a tenfold increase in the number of measurements used to calculate CIMT did not improve reproducibility. In addition, we found that observer biases caused differences in mean CIMT of a magnitude commonly reported as significant in intervention trials. Our results highlight the importance of good study design with concurrent controls and the need to ensure that no observer drift occurs between baseline and follow-up measurements when CIMT is used to monitor the effect of an intervention.
Journal of Medical Internet Research, 2021
Background Hypertension affects over 15% of the world’s population and is a significant global pu... more Background Hypertension affects over 15% of the world’s population and is a significant global public health and socioeconomic challenge. Mobile health (mHealth) services have been increasingly introduced to support hypertensive patients to improve their self-management behaviors, such as adherence to pharmacotherapy and lifestyle modifications. Objective This study aims to explore patients’ perceptions of mHealth services and the mechanisms by which the services support them to self-manage their hypertension. Methods A semistructured, in-depth interview study was conducted with 22 outpatients of the General Hospital of Ningxia Medical University from March to May 2019. In 2015, the hospital introduced an mHealth service to support community-dwelling outpatients with self-management of hypertension. Content analysis was conducted by following a grounded theory approach for inductive thematic extraction. Constant comparison and categorization classified the first-level codes with sim...
Medical Journal of Australia, 2001
Comment on: PBS/RPBS cost implications of trends and guideline recommendations in the pharmacolog... more Comment on: PBS/RPBS cost implications of trends and guideline recommendations in the pharmacological management of hypertension in Australia, 1994-1998. [Med J Aust. 2001
Medical Journal of Australia, 2003
had many principles in common. These included the need to assess and to consider overall cardiova... more had many principles in common. These included the need to assess and to consider overall cardiovascular risk rather than just blood pressure, to describe absolute risk rather than relative risk alone, and to stratify patients according to the severity of risk to determine prognosis and treatment. 1,2 However, these major guidelines differed in their recommendations for beginning drug treatment. JNC VI recommended that, in the absence of compelling indications such as previous myocardial infarction or diabetic nephropathy, drug treatment should begin with diuretics or -blockers. This was because, at that time, there was only limited evidence that the newer agents-such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers (CCBs) or ␣-blockers-reduced morbidity or mortality in patients with hypertension. 1 In contrast, the WHO-ISH 1999 guidelines recommended that any of these major classes of drugs could be used to initiate drug treatment, according to the clinical situation in the individual patient. This recommendation reflected the premise that the benefits of antihypertensive drugs were mainly dependent on their blood-pressurelowering efficacy rather than on effects specific to particular drug classes. 2 Most experts in the field agreed that these differences in recommendations arose from lack of evidence, and that randomised trials of the newer drugs were necessary to resolve the uncertainty. 1,2 Since the late 1990s, many clinical trials examining these issues have been completed, so that, by the turn of the century, there was sufficient evidence to establish that ACE inhibitors and CCBs do reduce the risks of coronary heart disease and stroke in patients with hypertension when compared with placebo. 3 In the past year, the results of two of the most awaited trials have become available. These are: ■ The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), the largest comparative study of blood-pressure-lowering drugs ever completed, 4 and ■ The Second Australian National Blood Pressure Study (ANBP2), a smaller head-to-head comparison of diuretics and ACE inhibitors, carried out entirely within general practice in Australia. 5 Here, we review, primarily, the results of ALLHAT and ANBP2 in the context of the accumulated evidence about the newer classes of blood-pressure-lowering drugs reported since JNC VI and WHO-ISH 1999 were published. 1,2 Our review is made more timely by the release of JNC VII in May this year, 6 with recommendations based predominantly on the outcomes of ALLHAT 4 and the recent European Guidelines, released in June 2003 by the European Society for Hypertension jointly with the European Society of Cardiology. 7 The importance of the effective treatment of hypertension has been reinforced in a most powerful way by the recent World Health Organization report (WHO Report 2002), 8 as highlighted in two shorter articles in the Lancet. 9,10 These reports confirm that, in developed countries, blood pressure is the single most important contributor to global mortality
Biochemical Pharmacology, 2015
Release of Ca(2+) from the sarcoplasmic reticulum (SR) through the cardiac ryanodine receptor (Ry... more Release of Ca(2+) from the sarcoplasmic reticulum (SR) through the cardiac ryanodine receptor (RyR2) is an essential step in cardiac excitation-contraction coupling. Excess Ca(2+) release due to overactive RyR2 can cause arrhythmia that can lead to cardiac arrest. Fragments derived from the carboxy-terminal domain of human glutathione transferase M2 (GSTM2C) specifically inhibit RyR2 activity. Our aim was to further improve this inhibition by mutagenesis and to assess the therapeutic potential of GSTM2C based peptides to treat Ca(2+) release-based arrhythmia. We generated several mutant variants of the C-terminal fragment GSTM2C H5-8 and from those mutant proteins we identified two (RM13 and SM2) that exhibited significantly greater inhibition of cardiac SR Ca(2+) release and single RyR2 channel activity. Flow cytometry analysis showed that these two mutant proteins as well as GSTM2C H5-8 are taken up by isolated adult mouse cardiomyocytes without the aid of any additional compounds, Ca(2+) imaging and isolated cell contraction measurements revealed that GSTM2C H5-8, SM2 and RM13 reduce the SR Ca(2+) release rate and the fractional shortening of adult mouse cardiomyocytes, while importantly increasing the rate of Ca(2+) removal from the sarcoplasm. These observations indicate that peptides derived from GSTM2C inhibit RyR2 at a cellular level and thus they may provide the basis for a novel therapeutic agent to treat arrhythmia and heart attack.
Australian family physician, 2003
Dizziness and loss of consciousness are common clinical problems presenting in general practice. ... more Dizziness and loss of consciousness are common clinical problems presenting in general practice. This article aims to provide the practitioner with a pragmatic and logical approach to identifying the cardiovascular causes of dizziness and loss of consciousness. A range of disorders with varying pathology cause a transient loss of consciousness associated with postural collapse (syncope) by interruption of blood flow to the brain. Syncope and seizures are the only common causes of recurrent episodes of loss of consciousness. The vasovagal reaction or 'common faint' and postural hypotension are both common and benign causes of syncope. Syncope can also result from cardiac causes that include disorders of cardiac rhythm and mechanical obstruction to cardiac output. Cardiac causes of syncope are associated with much higher morbidity and mortality than postural hypotension or fainting. Specific treatment is available for the various cardiac causes of syncope and thus accurate dia...
American journal of physiology. Heart and circulatory physiology, 2003
Chronic heart failure (CHF) is associated with adaptive structural changes at the alveolocapillar... more Chronic heart failure (CHF) is associated with adaptive structural changes at the alveolocapillary barrier that may be associated with altered protein permeability. Bidirectional protein movement across the barrier was studied in anesthetized rats with infarct-induced CHF by following (125)I-labeled albumin ((125)I-albumin) flux into the alveoli and the leakage of surfactant protein (SP)-B from the alveoli into the circulation. Three groups were studied: controls [0% left ventricular (LV) infarction], moderate infarct (25-45% LV infarction), and large infarct (>46% LV infarction). Wet and dry lung weights increased in the large infarct group (both P < 0.001), consistent with increased lung water and solid lung tissue. (125)I-albumin flux increased across the endothelial (P < 0.001) and epithelial (P < 0.01) components of the alveolocapillary barrier in the large infarct group. Plasma SP-B increased 23% with moderate infarcts (P < 0.05) and 97% with large infarcts (P &...
The Journal of pharmacology and experimental therapeutics, 1995
The effect of right heart failure on theophylline clearance was investigated in rats in which rig... more The effect of right heart failure on theophylline clearance was investigated in rats in which right ventricular pressure overload was produced by pulmonary artery constriction (PAC). Fifteen wk after the surgery, compared to sham-operated controls (n = 9), PAC rats (n = 9) showed markedly elevated mean central venous pressure (11 +/- 3 vs 1.44 +/- 0.88 mm Hg, P = .0001), and increased right ventricular weight (0.229 +/- 0.047 vs 0.124 +/- 0.013 g/100 g body weight, P = .0001). Centrilobular hepatic congestion was present in all PAC rats and total hepatic oxygen delivery was reduced significantly compared to controls (146 +/- 58 mumols/min vs. 206 +/- 28 mumol/min; P = .025). In the PAC group, theophylline clearance was reduced (0.82 +/- 0.12 ml/min vs. 0.96 +/- 0.13 ml/min in controls; P = .014), and there was a nonlinear correlation between theophylline clearance and total hepatic oxygen delivery (r = .82). These results suggest that in animals with PAC, metabolism of theophylline ...
The Clinical Teacher, 2008
‘C linical teaching is at the centre of medical education,’ states Prideaux et al., a view held b... more ‘C linical teaching is at the centre of medical education,’ states Prideaux et al., a view held by many clinicians and educators. Rarely, however, have clinicians been taught how to teach and many do not have the time to attend staff development programmes. Not only do good clinical teachers need to have skills to facilitate learning, but they also need to work in an environment that supports their efforts. It is important to recognise the barriers that face teachers and provide solutions and, although many of the barriers have been recognised, there has been limited research into solutions.
Journal of the American College of Cardiology, 1993
Journal of the American College of Cardiology, 1996
also studied. LV end-systolic and end-diastolic pressure-volume relationships (ESPVR & EDPVR) wer... more also studied. LV end-systolic and end-diastolic pressure-volume relationships (ESPVR & EDPVR) were measured using an intmvantdcular balloon. The data (means :t: SD, Rgure) indicate that, compared to normal he~ls, EsPVRs and EDPVRs of CHFc and CHFsx were shifted towards larger volumeS. There was a small leftward shift of the ESPVR of CHFEx and no significant change in EDPVR between CHF gmupe. Thus, El" blunted the rise in LVEDP, provided mild preservation of systOflo properflas but did not prevent the significant increase in chamber size (mmodeling) secondary to rapid pacing. The benefit.let effects of ET in CHF may relate more to peripheral than cardiac effects.
Heart, 1996
Ledingham JGG, et al. Skeletal muscle metabolism in heart failure: a 31P nuclear magnetic resonan... more Ledingham JGG, et al. Skeletal muscle metabolism in heart failure: a 31P nuclear magnetic resonance spectroscopy study of leg muscle. Clin Sci 1990;79:583-9.
Journal of Hypertension, 1992
Europace, 2007
To determine long-term effects of atrioventricular junction ablation and pacing (AVJAP) on cardia... more To determine long-term effects of atrioventricular junction ablation and pacing (AVJAP) on cardiac function and quality of life. Methods and results Prospective follow-up was performed on consenting patients recruited in two participating centres representing majority of the Australian intervention randomized control of rate in atrial fibrillation trial (AIRCRAFT) cohort after 4-7 years. All patients underwent history, physical examination, 24 h ambulatory ECG monitoring, and transthoracic echocardiogram. Quality of life questionnaires in original AIRCRAFT trial were re-administered including CAST, assessment quality of life, and sickness impact profile. Of the 63 eligible patients, 14 refused participation, and 1 patient was lost to follow-up. The remaining 48 patients (25 males, current mean age 74 + 7.5 years), 23 randomized to AVJAP and 25 to pharmacologic therapy (MED) were re-evaluated. In the MED group, LVEF was 62 + 11% at baseline, 63 + 10% at 6 months, 64 + 9% at 12 months, and 59 + 12% at 5 years (P , 0.01). In the AVJAP group LVEF was 54 + 19% at baseline, 55 + 13% at 6 months, 53 + 15% at 12 months, and 51 + 17% at 5 years (P ¼ 0.02). NYHA functional class was not statistically different between MED and AVJAP patients (1.4 vs. 1.5, P ¼ 0.48). Death occurred in 10 MED and 5 AVJAP patients. Survival analysis incorporating all 63 patients showed no statistical difference between the 2 treatment groups (P ¼ 0.26). The CAST quality of life questionnaire revealed that patients in the AVJAP group had fewer symptoms of irregular heart beat (P , 0.001), chest pain (P ¼ 0.02), and difficulty breathing (P ¼ 0.02). Psychosocial scores and overall life satisfaction were similar (P. 0.05). Conclusion In this long-term follow-up of the AIRCRAFT cohort, similar decline in LVEF and NYHA class was observed in both treatment groups. AVJAP patients have better quality of life with fewer symptoms. Based on improved quality of life, ablate and pace strategy for permanent atrial fibrillation should be considered for highly symptomatic patients refractory to pharmacologic therapy.
Clinical Science, 2001
Comment on: The effect of glutamate infusion on cardiac performance is independent of changes in ... more Comment on: The effect of glutamate infusion on cardiac performance is independent of changes in metabolism in patients undergoing routine coronary artery bypass surgery. [Clin Sci (Lond). 2001
Clinical and Experimental Pharmacology and Physiology, 1998
1. In conscious rabbits, when alerting stimuli elicit vasoconstriction in the ear vascular bed, t... more 1. In conscious rabbits, when alerting stimuli elicit vasoconstriction in the ear vascular bed, there is little or no associated change in cardiac output (CO), as measured by chronically implanted Doppler ultrasonic probes. 2. Local anaesthetic injected around the base of the ear substantially diminished the degree of the vasoconstriction elicited during responses. 3. Our results emphasize that selective cutaneous vasoconstriction, an integral part of the response to alerting stimuli in conscious animals, is part of a patterned redistribution of the CO, organized by the brain.
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Papers by Leonard Arnolda