Mehmood Butt

University of Birmingham, Birmingham, England, United Kingdom

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Publications (14)63.64 Total impact

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    ABSTRACT: Objectives Arterial and systolic elastance are important parameters determining effective functional interaction of heart and vessels. The aims of this study were to (i) compare arterial [arterial elastance index (EaI)] and ventricular [End-systolic elastance (Ees) and End-diastolic elastance (Eed)] elastance in subjects with obstructive sleep apnoea (OSA) and patients with treated ‘high-risk’ hypertension (HHT), and (ii) test whether these parameters in OSA patients can be improved by continuous positive airway pressure (CPAP) therapy. Methods Echocardiographic parameters of cardiac and vascular stiffness (EaI, Ees and Eed) were quantified in 28 patients with OSA (mean [SD] age 51 [11] years, 79% male) and 28 treated subjects with HHT (mean [SD] age 48 [12] years, 61% male). Twenty three OSA patients were treated with CPAP for median of 26 weeks. Ea was calculated from stroke volume and systolic BP and adjusted by body area (EaI). Both study groups had preserved and comparable left ventricle (LV) contractility. Results There was no significant differences in arterial elastance index (EaI, p=0.94), end-systolic elastance (Ees, p=0.5), end-diastolic elastance (Eed, p=0.63) and arterial-ventricular interaction (Ees/Ea, p=0.62) between OSA and HHT groups. After CPAP therapy, there was a significant reduction in arterial elastance index (EaI; paired t-test, p=0.013), and arterial-ventricular interaction (Ees/Ea; paired t-test, p=0.004). End-systolic elastance (Ees, p=0.17), end-diastolic elastance (Eed, p=0.66) parameters did not change significantly. Conclusions OSA patients and HHT patients have similar parameters of elastance and ventricular-arterial coupling. CPAP treatment in OSA patients significantly improved ventricular-arterial coupling.
    Journal of the American Society of Hypertension 09/2014; 8(9). DOI:10.1016/j.jash.2014.05.013 · 2.61 Impact Factor
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    ABSTRACT: Previous studies in obstructive sleep apnea (OSA) were limited by study cohorts with comorbidities that confound assessment of left ventricular (LV) systolic and diastolic function. We comprehensively evaluated LV function using 2-dimensional echocardiography (2DE), tissue Doppler imaging (TDI), and 3-dimensional echocardiography (3DE) in subjects moderate-severe OSA, who were compared with disease (patients with hypertension, no OSA) and healthy control subjects. A total of 120 subjects (n=40 each of matched OSA, hypertension and healthy cohorts) underwent echocardiographic examination for the assessment of septal and posterior wall thickness, LV mass index, LV volumes and ejection fraction, mitral valve inflow indices (E, A), mitral annular velocity (S, E'), and left atrial volume index (LAVI). OSA subjects were treated with continuous positive airway pressure (mean duration of 26 weeks), after which the echocardiographic parameters were reassessed. Posterior wall thickness and LV mass index were significantly higher in OSA and hypertensive groups compared with healthy. Systolic S velocity was reduced in OSA and hypertensive compared with healthy control subjects (P<0.05). Diastolic function (E/A, IVRT, and E/E') was impaired in both OSA and hypertensive groups. On 3DE, mean LAVI was significantly greater in OSA and hypertensive compared with healthy. In OSA patients, continuous positive airway pressure therapy resulted in reduction of the posterior wall thickness (P=0.02) and improvement in LV ejection fraction (P<0.05), systolic S velocity (P<0.05), and diastolic LV impairment parameters. Moderate to severe OSA causes structural and functional changes in V function and are comparable to that seen in hypertension. These abnormalities significantly improve after CPAP therapy.
    Circulation Heart Failure 03/2012; 5(2):226-33. DOI:10.1161/CIRCHEARTFAILURE.111.964106 · 5.89 Impact Factor
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    ABSTRACT: BACKGROUND: Previous studies have confirmed that cardiac structural and functional abnormalities exist in patients with malignant hypertension (MHT). The effect of long-term blood pressure control in MHT patients on cardiac structure and function is still unknown. METHODS: We performed detailed left ventricle (LV) assessment using two-dimensional (2DE) and three-dimensional (3DE) echocardiography, and tissue Doppler imaging (TDI) in patients with previous MHT (but now in stable phase) who were compared with patients with treated 'high risk' hypertension (HHT, but non-MHT) and healthy controls (HC). Vasodilator stress myocardial contrast echocardiography (in addition to wall motion analysis) was used to exclude significant coronary artery disease, as part of our comprehensive echocardiographic assessment. Septal and posterior wall thickness, LV mass index, LV volumes and ejection fraction, mitral valve inflow indices (E, A) mitral annular velocity (S, E') and left atrial volume index (LAVI), were calculated using 2DE, 3DE, and TDI. MHT patients had good blood pressure control for an average of 144months. RESULTS: A total of 95 subjects (MHT=15; HHT and HC=40 each) were studied. Both posterior and septal wall thickness were significantly higher in the MHT and hypertensive groups compared to normal controls with no difference between MHT and HHT. No significant difference in LV ejection fraction was found between the 3 groups. Increased LAVI (p<0.05 MHT vs. HC and HHT vs. HC), reduced 'S' velocity on TDI (p=0.05 MHT vs. HC and vs.HHT, p<0.001 HHT vs. HC) and higher E/E' (p=0.029 HHT vs. HC) and lower E/A ratio (p=0.001 MHT vs. HC, p<0.001 HHT vs. HC) values were detected in the two hypertensive groups. CONCLUSION: Despite long-term good blood pressure control, MHT patients have persistent structural and functional changes in LV function on echocardiography, comparable to that seen in HHT.
    International journal of cardiology 12/2011; 167(1). DOI:10.1016/j.ijcard.2011.11.077 · 4.04 Impact Factor
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    ABSTRACT: Obstructive sleep apnea is associated with increased cardiovascular morbidity and mortality. We investigated myocardial perfusion using real-time quantitative myocardial contrast echocardiography with concurrent assessment of macrovascular and microvascular endothelial dysfunction in normotensive subjects with moderate-to-severe obstructive sleep apnea, who were compared with hypertensive and healthy subjects, as well as the impact of continuous positive airway pressure treatment on obstructive sleep apnea subjects. We measured flow (hyperemia)-mediated dilation and response to glyceryl trinitrate of brachial artery (ultrasound), cutaneous perfusion responses to acetylcholine and sodium nitroprusside (laser Doppler), pulse wave velocity, and circulating endothelial and endothelial progenitor cells in a total of 108 subjects (n=36 each of matched obstructive sleep apnea, hypertension, and healthy cohorts). Subjects with obstructive sleep apnea and hypertension demonstrated abnormal myocardial perfusion (P<0.001 for both comparisons), attenuated brachial artery reactivity (P<0.001), and cutaneous perfusion responses (P<0.001) compared with healthy individuals. Both hypertensive and obstructive sleep apnea patients showed significant improvements in myocardial perfusion (P<0.01), brachial artery reactivity (P<0.001), and cutaneous perfusion responses (P<0.001) after 26 weeks of continuous positive airway pressure therapy. There were no significant differences in pulse wave velocity and endothelial cells across the 3 groups. Concomitant endothelial dysfunction and impaired myocardial perfusion are present in otherwise normal subjects with moderate-to-severe obstructive sleep apnea, and effective continuous positive airway pressure treatment reverses many of these macrovascular/microvascular abnormalities.
    Hypertension 09/2011; 58(3):417-24. DOI:10.1161/HYPERTENSIONAHA.111.170910 · 6.48 Impact Factor
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    ABSTRACT: Endothelial dysfunction is characteristic of patients with essential hypertension, but only limited data are available on different aspects of endothelial function in patients with malignant-phase hypertension. We investigated myocardial perfusion using real-time quantitative myocardial contrast echocardiography with concurrent assessment of macrovascular and microvascular endothelial damage/dysfunction in patients with previous malignant hypertension (but now in stable phase), who were compared with patients with treated "high-risk" hypertension (hypertension) and healthy controls. We measured flow (hyperemia)-mediated dilation and response to glyceryl trinitrate of brachial artery (ultrasound), microvascular (forearm) response to acetylcholine and sodium nitroprusside (laser Doppler), pulse wave velocity, circulating endothelial and endothelial progenitor cells in 15 patients with malignant hypertension, 40 matched patients with hypertension, and 40 healthy controls. Patients with malignant hypertension had impaired endothelial-dependant response to acetylcholine (P<0.001, but not to sodium nitroprusside) compared with hypertension and impaired reaction to both stimuli compared with healthy subjects (P<0.001). Patients with malignant hypertension had increased circulating endothelial cells (P=0.001), endothelial progenitors (P=0.008), and stiffness (P=0.003). Both hypertensive groups had impaired response to hyperemia and glyceryl trinitrate when compared with healthy controls (P<0.05). Both hypertensive groups had similar myocardial perfusion, which was significantly lower than in healthy controls. There were no significant differences in hyperemia and endothelium-independent stimuli between the 2 hypertensive groups. In conclusion, despite fairly well-controlled blood pressure, malignant hypertension patients had more pronounced abnormalities of macrovascular and microvascular function (which seem to be both endothelium dependent and endothelium independent) compared with patients with hypertension and healthy controls.
    Hypertension 03/2011; 57(3):490-6. DOI:10.1161/HYPERTENSIONAHA.110.166314 · 6.48 Impact Factor

  • Scientific Sessions on Arteriosclerosis, Thrombosis and Vascular Biology; 11/2010
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    ABSTRACT: The endothelium is a thin monocellular layer lining the entire human vascular system, separating blood from interstitium. It plays a core role in the vascular tone by releasing a variety of vasoactive substances, such as nitric oxide (NO) and endothelin. In addition to regulating vasomotion, the healthy endothelium also has anti-thrombotic (through prostacyclins), anti-inflammatory (through developmental endothelial locus-1{Del-1}) and anti-proliferative (through NO and prostaglandin I2) properties. All such mechanisms are regulated by a strict balance amongst several agonist and antagonist biochemical substances secreted by the endothelium. Endothelial dysfunction (ED) is a systemic process in which the endothelium loses the ability/capacity to maintain vascular equilibrium. ED is strongly associated with cardiovascular risk factors/diseases and can be assessed by a number of invasive and non invasive methods. Strict physiological and/or pharmacological management of cardiovascular risk factors improves the functional status of the endothelium and reduces the risk of future cardiac events. This review will provide an overview of the modern perception of endothelial biology, the methods of its assessment and interaction of the endothelium with cardiovascular risk factors and prognosis.
    Current pharmaceutical design 10/2010; 16(31):3442-54. DOI:10.2174/138161210793563383 · 3.45 Impact Factor
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    Mehmood Butt · Girish Dwivedi · Omer Khair · Gregory Yh Lip ·

    Expert Review of Cardiovascular Therapy 07/2009; 7(6):561-3. DOI:10.1586/erc.09.36
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    Mehmood Butt · Girish Dwivedi · Omer Khair · Gregory Y.H. Lip ·
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    ABSTRACT: Obstructive sleep apnea (OSA) is a common yet an under-diagnosed sleep related breathing disorder affecting predominantly middle-aged men. OSA is associated with many adverse health outcomes, including cardiovascular disease. Common OSA associated/induced cardiovascular disorders include coronary artery disease, heart failure, hypertension, cardiac arrhythmias and stroke, which further increase morbidity and mortality in the OSA population. Endothelial dysfunction, coagulopathy, impaired sympathetic drive, oxidative and inflammatory stress are the pathophysiological pathways suggested for the development of cardiovascular disease in OSA. The evidence would suggest that OSA should be considered as a cardiovascular risk factor, and is a treatable condition. Multiple studies using Continuous Positive Airway Pressure (CPAP) have shown improvements in the clinical state as well as retardation of disease progression. Therefore, patients with cardiovascular disease should be proactively screened for OSA and vice versa.
    International journal of cardiology 07/2009; 139(1):7-16. DOI:10.1016/j.ijcard.2009.05.021 · 4.04 Impact Factor
  • A Siddique · M Butt · E Shantsila · G Y H Lip ·
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    ABSTRACT: Antiplatelet therapy remains a cornerstone of modern management of atherothrombotic vascular disease. For many years, aspirin has been the mainstay of initial antiplatelet drug management in coronary heart disease, while the need for inhibition of other platelet activation pathways has led to the development of various other antiplatelet drugs, such as clopidogrel. An improved understanding of the underlying mechanisms involved in thrombogenesis has paved the way for further development of newer antiplatelet drug therapies. Various clinical studies have probed the effectiveness and risk profile of the newer antiplatelet drugs, such as prasugrel, in comparison with currently available drugs. Some newer agents such as prasugrel are close to being approved for clinical use, whereas other agents such as cangrelor and AZD6140 are in phase 3 clinical trials. New drug classes, such as the thromboxane receptor antagonists (such as NCX-4016 and S18886), as well as platelet adhesion antagonists and thrombin receptor antagonists are similarly being evaluated for their efficacy and risk profile in phase I and II trials.
    International Journal of Clinical Practice 06/2009; 63(5):776-89. DOI:10.1111/j.1742-1241.2009.02058.x · 2.57 Impact Factor
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    Mehmood Butt · Derek Connolly · Gregory Y H Lip ·
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    ABSTRACT: Cardiovascular medicine has evolved over the last few decades, with the advent of percutaneous interventional treatments. In particular, balloon angioplasty and, subsequently, coronary stenting has revolutionized our current perspective of stable and unstable coronary artery disease management. However, the long-term results of stent usage have been blighted by the dual problems of in-stent restenosis and stent thrombosis. Whilst stent thrombosis became much less frequent with the introduction of dual-antiplatelet therapy, restenosis remained a significant problem. Intense work on stent development has successfully led to the introduction of drug-eluting stents (DES) in an effort to address this problem. Randomized trials have consistently proven the superior efficacy of DES over bare metal stents, in elective patients, acute coronary syndromes and patients with diabetes mellitus. Nevertheless, the routine use of DES in by-pass venous graft disease remains debatable. The initial DES used sirolimus and paclitaxel are now being joined by newer stents releasing drugs, such as everolimus, zotarolimus and tacrolimus. Ongoing developments with the stent platform and the polymer coating are also gradually improving the performance of these stents in clinical practice. More recently, the idea of antibody-coated stents that would encourage epithelialization of stent struts by endothelial progenitor cells recruitment has gained attraction among interventionists, with a possible beneficial impact on reducing the incidence of restenosis.
    Future Cardiology 04/2009; 5(2):141-57. DOI:10.2217/14796678.5.2.141
  • Suresh Krishnamoorthy · Mehmood Butt · Gregory Y.H. Lip ·
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    ABSTRACT: Atrial septal defect (ASD) accounts for approximately a third of all congenital heart disease in adults. It is rarely diagnosed and less likely to cause any symptoms during infancy, but approximately more than half become symptomatic around their fifth decade. In clinical setting it commonly presents as exertional dyspnoea, atrial arrhythmias, right heart failure and is rarely related to the thromboembolic complications due to paradoxical embolism. ASD is usually well tolerated in pregnancy with low risk of miscarriages, stillbirth, preterm delivery and perinatal mortality. We report an interesting case of undiagnosed large ostium secundum atrial septal defect in a young pregnant lady presented as 'asymptomatic hypoxia'. All pregnant women with hypoxia either pre or post-partum should be investigated to rule out any undiagnosed intra cardiac shunts to minimise maternal and foetal complications.
    International journal of cardiology 02/2009; 143(2):e34-6. DOI:10.1016/j.ijcard.2008.12.039 · 4.04 Impact Factor
  • Mehmood Butt · Gregory Y H Lip ·

    American Journal of Hypertension 01/2009; 21(12):1275-6. DOI:10.1038/ajh.2008.303 · 2.85 Impact Factor
  • Gregory Y H Lip · Mehmood Butt ·

    European Heart Journal 11/2008; 29(21):2585-6. DOI:10.1093/eurheartj/ehn451 · 15.20 Impact Factor