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Featured researches published by N. Collins.


Catheterization and Cardiovascular Interventions | 2012

Pseudoaneurysm after transradial cardiac catheterization: Case series and review of the literature

N. Collins; Rodrigo Wainstein; Michael R. Ward; Rohan Bhagwandeen; Vladimir Dzavik

Introduction: Radial artery access for diagnostic and therapeutic procedures offers clear advantages in terms of vascular complications. While radial artery occlusion may occasionally complicate radial artery access, new methods of hemostasis are now utilized to avoid this complication. In contrast, pseudoaneurysm following radial artery access is an extremely uncommon complication. Methods: We describe a series of patients who developed radial artery pseudoaneurysm after their procedure. Results: Five patients developed radial pseudoaneurysm after diagnostic and interventional procedures, likely reflecting inadequate hemostasis following the procedure and delayed bleeding complicating systemic anticoagulation. Conclusions: While uncommon, radial artery pseudoaneurysm may complicate cardiac catheterization procedures, with anticoagulation an important contributor. The clinical presentation, likely precipitating mechanisms and treatment options are discussed.


Internal Medicine Journal | 2014

Sudden cardiac death complicating acute myocardial infarction following synthetic cannabinoid use

R. Tse; S. Kodur; B. Squires; N. Collins

1 Dux S, Bishara J, Marom D, Blum I, Pitlik S. Medroxyprogesterone acetate-induced secondary adrenal insufficiency. Ann Pharmacother 1998; 32: 134. 2 Krueger RB, Hembree W, Hill M. Prescription of medroxyprogesterone acetate to a patient with pedophilia, resulting in Cushing’s syndrome and adrenal insufficiency. Sex Abuse 2006; 18: 227–8. 3 De Matteo R, May CN. Glucocorticoid-induced renal vasodilatation is mediated by a direct renal action involving nitric oxide. Am J Physiol Regul Integr Comp Physiol 1997; 273: R1972–R9. 4 De Matteo R, May CN. Inhibition of prostaglandin and nitric oxide synthesis prevents cortisol-induced renal vasodilatation in sheep. Am J Physiol Regul Integr Comp Physiol 1999; 276: R1125–R31. 5 Thomas CP, Liu KZ, Vats HS. Medroxyprogesterone acetate binds the glucocorticoid receptor to stimulate α-ENaC and SGK1 expression in renal collecting duct epithelia. Am J Physiol Renal Physiol 2006; 290: F306–F12. 6 Arias-Loza P-A, Muehlfelder M, Elmore SA, Maronpot R, Hu K, Blode H et al. Differential effects of 17β-estradiol and of synthetic progestins on aldosterone-salt-induced kidney disease.


Heart Lung and Circulation | 2015

Peri-operative Levosimendan in Patients Undergoing Cardiac Surgery: An Overview of the Evidence.

William Y. Shi; Sheila Li; N. Collins; David B. Cottee; Bruce Bastian; A. James; Ross Mejia

Levosimendan, a calcium sensitiser, has recently emerged as a valuable agent in the peri-operative management of cardiac surgery patients. Levosimendan is a calcium-sensitising ionodilator. By binding to cardiac troponin C and reducing its calcium-binding co-efficient, it enhances myofilament responsiveness to calcium and thus enhances myocardial contractility without increasing oxygen demand. Current evidence suggests that levosimendan enhances cardiac function after cardiopulmonary bypass in patients with both normal and reduced left ventricular function. In addition to being used as post-operative rescue therapy for low cardiac output syndrome, a pre-operative levosimendan infusion in high risk patients with poor cardiac function may reduce inotropic requirements, the need for mechanical support, the duration of intensive care admissions as well as post-operative mortality. Indeed, it is these higher-risk patients who may experience a greater degree of benefit. Larger, multicentre randomised trials in cardiac surgery will help to elucidate the full potential of this agent.


International Journal of Cardiology | 2017

Clozapine and incidence of myocarditis and sudden death – Long term Australian experience

A. Khan; Asma Ashraf; David Baker; M. Al-Omary; Lindsay Savage; Avedis Ekmejian; R. Singh; Stephen Brienesse; Tazeen Majeed; Tracy Gordon; Vincent Drinkwater; N. Collins

BACKGROUND Clozapine is the cornerstone of therapy for refractory schizophrenia; however, the potential for cardiotoxicity is an important limitation in its use. In the current analysis we sought to evaluate the long term cardiac outcomes of clozapine therapy. METHODS All-cause mortality, incidence of sudden death and time to myocarditis were assessed in a cohort of patients maintained on clozapine between January 2009 and December 2015. All patients had regular electrocardiograms, complete blood count, clozapine levels and echocardiography as part of a formal protocol. RESULTS A total of 503 patients with treatment-resistant schizophrenia were maintained on clozapine during the study period of which 93 patients (18%) discontinued therapy with 29 (6%) deaths. The incidence of sudden death and myocarditis were 2% (n=10) and 3% (n=14) respectively. Amongst patients with sudden death, 7 out of 10 (70%) were documented to have used illicit drugs prior to death, with a tendency to weight gain also noted. The mean time to myocarditis post clozapine commencement was 15±7days. The reduction in left ventricular ejection fraction in those with myocarditis was 11±2%. CONCLUSION Myocarditis and sudden cardiac death are uncommon but clinically important complications in a cohort of patients followed while maintained on clozapine undergoing regular cardiac assessment. Further studies are required to document the role of preventive measures for left ventricular dysfunction and sudden cardiac death in this population.


Internal Medicine Journal | 2012

Prevalence of Helicobacter pylori positivity in patients undergoing percutaneous coronary intervention.

C. Hiew; A. Duggan; T. de Malmanche; R. Hatton; F. Baker; John Attia; N. Collins

Background The adverse effect of haemorrhagic complications after percutaneous coronary intervention (PCI) on outcome is well established with Helicobacter pylori infection known to be an important precipitant of peptic ulcer disease in patients receiving non‐steroidal anti‐inflammatory drug therapy. The prevalence of H. pylori positivity in patients undergoing PCI and receiving subsequent antiplatelet therapy is unknown.


Internal Medicine Journal | 2017

Incidence, Time of Occurrence and Response to Heart Failure Therapy in Patients with Anthracycline Cardiotoxicity.

A. Khan; Asma Ashraf; R. Singh; Aadil Rahim; Walid Rostom; Mumtaz Hussain; Ian W. Renner; N. Collins

Anthracyclines are commonly used chemotherapeutic medications.


Congenital Heart Disease | 2017

Cardiac remodeling in preterm infants with prolonged exposure to a patent ductus arteriosus.

Koert de Waal; Nilkant Phad; N. Collins; Andrew J. Boyle

BACKGROUND Sustained volume load due to a patent ductus arteriosus (PDA) leads to cardiac remodeling. Remodeling changes can become pathological and are associated with cardiovascular disease progression. Data on remodeling changes in preterm infants is not available. METHODS Clinical and echocardiography data were collected in preterm infants <30 weeks gestation on postnatal day 3 and then every 7-14 days until closure of the ductus arteriosus. Images were analyzed using conventional techniques and speckle tracking. Remodeling changes of infants with prolonged (>14 days) exposure to a PDA were compared to control infants without a PDA. RESULTS Thirty out of 189 infants had prolonged exposure to a PDA. The left heart remodeled to a larger and more spherical shape and thus significantly increased in volume. Most changes occurred in the first 4 weeks, plateaued, and then returned to control values. Systolic function and estimates of filling pressure increased and effective arterial elastance reduced with a PDA, however contractility was unchanged. Wall thickness increased after 4 weeks of increased volume exposure. CONCLUSION The preterm PDA induces early and significant remodeling of the left heart. A compensated cardiac physiology was seen with preserved systolic function, suggesting adaptive rather than pathological remodeling changes with prolonged exposure to a PDA.


Heart Lung and Circulation | 2011

Stroke during Pregnancy: Therapeutic Options and Role of Percutaneous Device Closure

Lisa Dark; Andre Loiselle; R. Hatton; Rohan Bhagwandeen; N. Collins

Percutaneous device closure of patent foramen ovale has developed into a therapeutic option for patients with presumed cryptogenic stroke. The appropriate use of these therapies relies on appropriate clinical assessment, as well as an understanding of the potential advantages of certain closure devices. Pregnancy is an uncommon scenario for stroke, but nonetheless represents a hypercoaguable state which may predispose to thromboembolism. We describe a case of stroke during pregnancy treated with percutaneous device closure; the role of, and alternatives to, device closure are discussed, as are specific issues related to device selection and the interventional procedure.


Heart Lung and Circulation | 2015

Influence of Age on Outcome in Patients with Pulmonary Arterial Hypertension

Sreekanth Kodur; Waheed Ahmad; Melanie Heittarachi; Glenn Reeves; John Attia; Daniel Barker; N. Collins

BACKGROUND The development of effective orally administered medical therapy for pulmonary arterial hypertension (PAH) has made a significant impact on outcome in patients with PAH. Identification of patient groups likely to derive optimal benefit is important, given cost and potential side effects; the clinical effectiveness of these therapies in older patients with PAH is unclear as the presence of co-morbidity may limit benefits of therapy. AIMS We evaluated the epidemiology of PAH in a contemporary cohort to assess the influence of age on long-term outcome using PAH-specific therapies. RESULTS A total of 119 patients (88% female; mean age 65±12 years) were reviewed, comprising 52% with underlying connective tissue disease. Bosentan was the PAH specific agent most frequently used. The baseline 6MWT distance in the entire cohort was 304m with age associated with a significant decline in 6MWT. CONCLUSIONS In a large cohort of patients treated with PAH-specific therapies, patients less than 55 years of age showed improvement in 6MWT with older patients demonstrating stabilisation or decline.


Cardiology in The Young | 2017

Assessment of cerebral blood flow in adult patients with aortic coarctation.

Rachel H.X. Wong; Waheed Ahmad; A. Davies; Neil J. Spratt; Andrew J. Boyle; Christopher Levi; Peter R. C. Howe; N. Collins

BACKGROUND Survival into adult life in patients with aortic coarctation is typical following surgical and catheter-based techniques to relieve obstruction. Late sequelae are recognised, including stroke, hypertension, and intracerebral aneurysm formation, with the underlying mechanisms being unclear. We hypothesised that patients with a history of aortic coarctation may have abnormalities of cerebral blood flow compared with controls. METHODS Patients with a history of aortic coarctation underwent assessment of cerebral vascular function. Vascular responsiveness of intracranial vessels to hypercapnia and degree of cerebral artery stiffness using Doppler-derived pulsatility indices were used. Response to photic stimuli was used to assess neurovascular coupling, which reflects endothelial function in response to neuronal activation. Patient results were compared with age- and sex-matched controls. RESULTS A total of 13 adult patients (males=10; 77%) along with 13 controls underwent evaluation. The mean age was 36.1±3.7 years in the patient group. Patients with a background of aortic coarctation were noted to have increased pulse pressure on blood pressure assessment at baseline with increased intracranial artery stiffness compared with controls. Patients with a history of aortic coarctation had less reactive cerebral vasculature to hypercapnic stimuli and impaired neurovascular coupling compared with controls. RESULTS Adult patients with aortic coarctation had increased intracranial artery stiffness compared with controls, in addition to cerebral vasculature showing less responsiveness to hypercapnic and photic stimuli. Further studies are required to assess the aetiology and consequences of these documented abnormalities in cerebral blood flow in terms of stroke risk, cerebral aneurysm formation, and cognitive dysfunction.

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A. Khan

John Hunter Hospital

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C. Hiew

John Hunter Hospital

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