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Kaivan Khavandi

Kaivan Khavandi, Reza Aghamohammadzadeh, Matthew Luckie, Jack Brownrigg, Uazman Alam, Rajdeep Khattar, Rayaz A Malik, Anthony M Heagerty, Adam S Greenstein
BACKGROUND: Small artery pathophysiology is frequently invoked as a cause of obesity-related diastolic heart failure. However, evidence to support this hypothesis is scant, particularly in humans. METHODS AND RESULTS: To address this, we studied human small artery structure and function in obesity and looked for correlations between vascular parameters and diastolic function. Seventeen obese patients with metabolic syndrome and 5 control participants underwent echocardiography and subcutaneous gluteal fat biopsy...
April 11, 2017: Journal of the American Heart Association
Kaivan Khavandi, Rachael A Baylie, Sarah A Sugden, Majid Ahmed, Viktoria Csato, Philip Eaton, David C Hill-Eubanks, Adrian D Bonev, Mark T Nelson, Adam S Greenstein
Activation of Ca2+ -sensitive, large-conductance potassium (BK) channels in vascular smooth muscle cells (VSMCs) by local, ryanodine receptor-mediated Ca2+ signals (Ca2+ sparks) acts as a brake on pressure-induced (myogenic) vasoconstriction-a fundamental mechanism that regulates blood flow in small resistance arteries. We report that physiological intraluminal pressure within resistance arteries activated cGMP-dependent protein kinase (PKG) in VSMCs through oxidant-induced formation of an intermolecular disulfide bond between cysteine residues...
October 11, 2016: Science Signaling
Ian Sabir, Kaivan Khavandi, Jack Brownrigg, A John Camm
Anticoagulation is the most-important intervention to prevent stroke in patients with atrial fibrillation (AF). Despite a lower point prevalence of AF in Asian communities and Asian countries than in other populations, individuals of Asian ethnicity are at a disproportionately high risk of stroke and have greater consequent mortality. Warfarin and other vitamin K antagonists are conventionally used for anticoagulation, and demonstrably reduce the risk of stroke and all-cause mortality in patients with AF. The use of warfarin in Asian countries is suboptimal, primarily owing to the universal challenge of achieving controlled anticoagulation with an unpredictable drug as well as concerns about the particularly high-risk of haemorrhage in Asian patients...
May 2014: Nature Reviews. Cardiology
Reza Hajhosseiny, Kaivan Khavandi, Naheed Jivraj, Soudeh Mashayekhi, David J Goldsmith, Rayaz A Malik
INTRODUCTION: The prevalence of diabetic nephropathy is increasing as a consequence of the global epidemic of diabetes, and the complications of diabetic nephropathy are unsurprisingly legion. Blockade of the renin-angiotensin-aldosterone system (RAAS) has formed the mainstay of management, but despite this, most individuals will suffer premature cardiovascular events, and many will progress to end-stage renal disease. Given the heterogeneity of pathologies, it is perhaps naïve to hope that blocking a single neurohormonal pathway will protect against the myriad of pathogenetic mechanisms that conspire to cause the injuries seen with diabetes...
April 2014: Expert Opinion on Investigational Drugs
Andrew J Kwok, Meghavi Mashar, Kaivan Khavandi, Ian Sabir
Dipeptidyl-peptidase-IV (DPP-IV) inhibitors are a new class of oral hypoglycaemic agents recently approved for the management of type 2 diabetes mellitus. Early data suggested that they had a positive impact on the cardiovascular system: treatment appeared to result in improvements in cardiac performance, blood pressure and lipid levels. However, recent clinical findings bring this into question. Our understanding of the physiological actions of these agents is complicated by the fact that DPP-IV has a wide range of substrates in addition to glucagon-like peptide 1...
May 2014: Trends in Cardiovascular Medicine
Kaivan Khavandi, Halima Amer, Bashar Ibrahim, Jack Brownrigg
Diabetes is a major and growing public health challenge which threatens to overwhelm medical services in the future. Type 2 diabetes confers significant morbidity and mortality, most notably with target organ damage to the eyes, kidneys, nerves and heart. The magnitude of cardiovascular risk associated with diabetes is best illustrated by its position as a coronary heart disease risk equivalent. Complications related to neuropathy are also vast, often working in concert with vascular abnormalities and resulting in serious clinical consequences such as foot ulceration...
September 2013: Therapeutic Advances in Chronic Disease
Reza Hajhosseiny, Ronak Rajani, Kaivan Khavandi, Frédéric A Sebag, Soudeh Mashayekhi, Matthew Wright, David Goldsmith
BACKGROUND: Electrocardiographic early repolarization (ER) occurring in <5% of general/atherosclerotic populations, is a marker of sudden cardiac death (SCD). The prevalence of ER in chronic kidney disease (CKD) patients, in whom SCD is common, is unknown. We aimed to determine the prevalence, contributing factors, and relationship of ER to all-cause mortality and progression to dialysis in CKD patients. METHODS: A retrospective study of 197 patients with stage 3-5 CKD...
2013: Frontiers in Physiology
Khaled M Musallam, Faek R Jamali, Frits R Rosendaal, Toby Richards, Donat R Spahn, Kaivan Khavandi, Iskandar Barakat, Benjamin Demoss, Luca A Lotta, Flora Peyvandi, Pier M Sfeir
Background. Identification and management of risk factors for stroke following isolated coronary artery bypass grafting (CABG) could potentially lower the risk of such serious morbidity. Methods. We retrieved data for 30-day stroke incidence and perioperative variables for patients undergoing isolated CABG and used multivariate logistic regression to assess the adjusted effect of preoperative hematocrit concentration on stroke incidence. Results. In 2,313 patients (mean age 65.9 years, 73.6% men), 43 (1.9%, 95% CI: 1...
2013: Anemia
Kaivan Khavandi, Meena Arunakirinathan, Adam S Greenstein, Anthony M Heagerty
Prevention of target organ damage represents the El Dorado for clinicians who treat hypertension. Although many of the cardiovascular sequelae of chronic hypertension are due to large artery atherosclerosis, an equal number are due to small artery dysfunction. These microvascular complications include eye disease (retinopathy), kidney failure, diastolic dysfunction of the heart and small vessel brain disease leading to stroke syndromes, dementia and even depression. Examination of the retinal vasculature represents the only way to reliably derive information regarding small arteries responsible for these diverse pathologies...
June 2013: Current Hypertension Reports
Kaivan Khavandi, Jack Brownrigg, Mohammed Hankir, Harpreet Sood, Naveed Younis, Joy Worth, Adam Greenstein, Handrean Soran, Anthony Wierzbicki, David J Goldsmith
In recent decades we have seen a surge in the incidence of diabetes in industrialized nations; a threat which has now extended to the developing world. Type 2 diabetes is associated with significant microvascular and macrovascular disease, with considerable impact on morbidity and mortality. Recent evidence has cast uncertainty on the benefits of very tight glycaemic goals in these individuals. The natural history of disease follows an insidious course from disordered glucose metabolism in a pre-diabetic state, often with metabolic syndrome and obesity, before proceeding to diabetes mellitus...
January 2014: Current Vascular Pharmacology
Constantina Chrysochou, Robert N Foley, James F Young, Kaivan Khavandi, Ching M Cheung, Philip A Kalra
BACKGROUND: Many physicians retain reservations regarding the routine prescription of renin-angiotensin blockade (RAB) in patients with atheromatous renovascular disease (ARVD). Conversely, these patients are in most need of the cardio- and renal protection offered by RAB. This reservation is mostly because of fear of precipitating acute renal deterioration. We aimed to study whether RAB can be used safely in ARVD patients and whether it altered their outcome. METHODS: Prospective observational study of all ARVD patients presenting to our tertiary referral centre from 1999-2009...
April 2012: Nephrology, Dialysis, Transplantation
Khaled M Musallam, Hani M Tamim, Toby Richards, Donat R Spahn, Frits R Rosendaal, Aida Habbal, Mohammad Khreiss, Fadi S Dahdaleh, Kaivan Khavandi, Pierre M Sfeir, Assaad Soweid, Jamal J Hoballah, Ali T Taher, Faek R Jamali
BACKGROUND: Preoperative anaemia is associated with adverse outcomes after cardiac surgery but outcomes after non-cardiac surgery are not well established. We aimed to assess the effect of preoperative anaemia on 30-day postoperative morbidity and mortality in patients undergoing major non-cardiac surgery. METHODS: We analysed data for patients undergoing major non-cardiac surgery in 2008 from The American College of Surgeons' National Surgical Quality Improvement Program database (a prospective validated outcomes registry from 211 hospitals worldwide in 2008)...
October 15, 2011: Lancet
Philip A Kalra, Constantina Chrysochou, Darren Green, Ching M Cheung, Kaivan Khavandi, Sebastian Sixt, Aljoscha Rastan, Thomas Zeller
BACKGROUND: Around 16% of all patients who present with atheromatous renovascular disease (ARVD) in the United States undergo revascularization. Historically, patients with advanced chronic kidney disease (CKD) have been considered least likely to show improvement in renal functional terms, or survival. We aimed to investigate whether differences in outcomes after revascularization compared to medical management might be observed in ARVD patients if stratified by their CKD classes. METHODS: Two prospective cohorts, a UK center with a traditionally conservative approach, and a German center who undertook a proactive revascularization approach, were compared...
January 1, 2010: Catheterization and Cardiovascular Interventions
Kaivan Khavandi, Ali Khavandi, Omar Asghar, Adam Greenstein, Sarah Withers, Anthony M Heagerty, Rayaz A Malik
Diabetic individuals have a significantly increased likelihood of developing cardiovascular disease. Whilst part of this association is explained by the presence of concomitant risk factors, large epidemiological studies have consistently reported diabetes as a strong risk factor for the development of heart failure after adjusting for such covariates. This has resulted in the notion that there is a distinct cardiomyopathy specific to diabetes, termed 'diabetic cardiomyopathy'. The natural history is characterized by a latent subclinical period, during which there is evidence of diastolic dysfunction and left ventricular hypertrophy, before overt clinical deterioration and systolic failure ensue...
June 2009: Best Practice & Research. Clinical Endocrinology & Metabolism
Adam S Greenstein, Anna Price, Kazuhiko Sonoyama, Angela Paisley, Kaivan Khavandi, Sarah Withers, Linda Shaw, Oscar Paniagua, Rayaz A Malik, Anthony M Heagerty
Type 2 diabetes mellitus profoundly changes small artery remodeling in response to hypertension. Abnormal increases of both wall thickness and lumen diameter are associated with an increased mortality. Changes to small artery structure in response to blood pressure (BP) in patients with type 1 diabetes mellitus have never been examined. In 1997, 17 patients with type 1 diabetes mellitus and 9 control subjects underwent in vitro assessment of gluteal-fat small arteries using pressure myography. Patients with BP <140/90 mm Hg (systolic BP: 119+/-3 mm Hg; n=12) had normal-resistance artery structure...
July 2009: Hypertension
Omar Asghar, Ahmed Al-Sunni, Kaivan Khavandi, Ali Khavandi, Sarah Withers, Adam Greenstein, Anthony M Heagerty, Rayaz A Malik
Diabetic cardiomyopathy is a distinct primary disease process, independent of coronary artery disease, which leads to heart failure in diabetic patients. Epidemiological and clinical trial data have confirmed the greater incidence and prevalence of heart failure in diabetes. Novel echocardiographic and MR (magnetic resonance) techniques have enabled a more accurate means of phenotyping diabetic cardiomyopathy. Experimental models of diabetes have provided a range of novel molecular targets for this condition, but none have been substantiated in humans...
May 2009: Clinical Science (1979-)
Adam S Greenstein, Kaivan Khavandi, Sarah B Withers, Kazuhiko Sonoyama, Olivia Clancy, Maria Jeziorska, Ian Laing, Allen P Yates, Philip W Pemberton, Rayaz A Malik, Anthony M Heagerty
BACKGROUND: Inflammation in adipose tissue has been implicated in vascular dysfunction, but the local mechanisms by which this occurs are unknown. METHODS AND RESULTS: Small arteries with and without perivascular adipose tissue were taken from subcutaneous gluteal fat biopsy samples and studied with wire myography and immunohistochemistry. We established that healthy adipose tissue around human small arteries secretes factors that influence vasodilation by increasing nitric oxide bioavailability...
March 31, 2009: Circulation
Kazuhiko Sonoyama, Adam Greenstein, Anna Price, Kaivan Khavandi, Tony Heagerty
At the level of the small artery, essential hypertension is associated with eutrophic inward remodeling. This involves reduction in lumen diameter by an increase in wall thickness. Previously thought to involve either hypertrophy or hyperplasia of the vascular smooth muscle cells in the media, it is now felt to be mediated by a functional property of the wall: myogenic tone. This is the ability of an artery to contract in response to an increase in intraluminal pressure. This autoregulatory function is also vital to ensure stabilisation of distal capillary pressures and so prevent, or limit, organ damage...
December 2007: Therapeutic Advances in Cardiovascular Disease
Kaivan Khavandi, Adam S Greenstein, Kazuhiko Sonoyama, Sarah Withers, Anna Price, Rayaz A Malik, Anthony M Heagerty
No abstract text is available yet for this article.
February 2009: Nephrology, Dialysis, Transplantation
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