Search

Your search keyword '"Kal Asrress"' showing total 6 results
Start Over Author "Kal Asrress"
6 results on '"Kal Asrress"'

1. Effects of Epicardial and Endocardial Cardiac Resynchronization Therapy on Coronary Flow: Insights From Wave Intensity Analysis

Author

Simon Claridge, Zhong Chen, Tom Jackson, Kalpa De Silva, Jonathan Behar, Manav Sohal, Jessica Webb, Eoin Hyde, Matthew Lumley, Kal Asrress, Rupert Williams, Julian Bostock, Motin Ali, Jaswinder Gill, Mark O'Neill, Reza Razavi, Steve Niederer, Divaka Perera, and Christopher Aldo Rinaldi

Subjects
cardiac resynchronization therapy, coronary flow, endocardial pacing, wave intensity, Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Background The increase in global coronary flow seen with conventional biventricular pacing is mediated by an increase in the dominant backward expansion wave (BEW). Little is known about the determinants of flow in the left‐sided epicardial coronary arteries beyond this or the effect of endocardial pacing stimulation on coronary physiology. Methods and Results Eleven patients with a chronically implanted biventricular pacemaker underwent an acute hemodynamic and electrophysiological study. Five of 11 patients also took part in a left ventricular endocardial pacing protocol at the same time. Conventional biventricular pacing, delivered epicardially from the coronary sinus, resulted in a 9% increase in flow (average peak velocity) in the left anterior descending artery (LAD), mediated by a 13% increase in the area under the BEW (P=0.004). Endocardial pacing resulted in a 27% increase in LAD flow, mediated by a 112% increase in the area under the forward compression wave (FCW) and a 43% increase in the area under the BEW (P=0.048 and P=0.036, respectively). There were no significant changes in circumflex parameters. Conventional biventricular pacing resulted in homogenization of timing of coronary flow compared with baseline (mean difference in time to peak in the LAD versus circumflex artery: FCW 39 ms [baseline] versus 3 ms [conventional biventricular pacing], P=0.008; BEW 47 ms [baseline] versus 8 ms [conventional biventricular pacing], P=0.004). Conclusions Epicardial and endocardial pacing result in increased coronary flow in the left anterior descending artery and homogenization of the timing of waves that determine flow in the LAD and the circumflex artery. The increase in both the FCW and the BEW with endocardial pacing may be the result of a more physiological activation pattern than that of epicardial pacing, which resulted in an increase of only the BEW.

Published
2015
Full Text
View/download PDF

2. 14 Differential effects of exercise and nitrates on invasive haemodynamics in patients with coronary artery disease

Author

Jan Schreuder, Stam Kapetenakis, Daniel Burkhoff, Kal Asrress, Simone Rivolo, Jack Lee, Satpal Arri, Rupert Williams, Tiffany Patterson, Divaka Perera, Brian Clapp, Natalia Briceno, Simon Redwood, and Michael S. Marber

Subjects
medicine.medical_specialty, Supine position, Cath lab, business.industry, Ischemia, Hemodynamics, Vasodilation, Disease, medicine.disease, Coronary artery disease, Internal medicine, medicine, Cardiology, In patient, business
Abstract

Background Exertional angina and the response to nitrates have been recognised for over two centuries. This ischaemic cascade and the mechanistic relief by nitrates has not been extensively studied. The aim was to identify these precise haemodynamic changes. Methods In 31 patients with exertional angina and coronary artery disease, real-time simultaneous LV pressure-volume (PV) relations and invasive measures of coronary flow were performed in the cathlab. A novel software system was developed to analyse these simultaneous data. Results Compared to control, exercise induced ischaemia (supine cath lab ergometer) led to a rightward, upward shift in end-systolic (39±14 versus 71±31 mL; p Conclusions These data support the adverse haemodynamic consequences of ischaemia and the systemic and coronary vasodilatory effects of nitrates. The novel technology developed and used to assess real-time ventricular-arterial interaction has the potential to facilitate future works investigating haemodynamic change induced by disease states and therapeutic interventions.

Published
2018

3. Collateral Formation in the Absence of Obstructive Coronary Artery Disease: Potential New Pathways in Cardioprotection

Author

Michael S. Marber, Simon Redwood, and Kal Asrress

Subjects
Male, Cardioprotection, medicine.medical_specialty, Collateral, business.industry, MEDLINE, Collateral Circulation, Coronary Artery Disease, medicine.disease, Coronary artery disease, Coronary Circulation, Internal medicine, medicine, Cardiology, Humans, Female, Pharmacology (medical), Cardiology and Cardiovascular Medicine, business
Published
2011

4. 6 Unravelling the mechanisms of mental stress vs exercise induced myocardial ischaemia

Author

Brian Clapp, Simon Redwood, R Cooke, Kal Asrress, Tiffany Patterson, Michael S. Marber, Matthew Lumley, Divaka Perera, Rupert Williams, James Coutts, Satpal Arri, Howard Ellis, and Muhammed Zeeshan Khawaja

Subjects
medicine.medical_specialty, Myocardial ischaemia, business.industry, Ischemia, Exercise stress, medicine.disease, Mental arithmetic, Surgery, Stenosis, Rate pressure product, Mental stress, Internal medicine, medicine, Cardiology, Cardiology and Cardiovascular Medicine, business, Stroop effect
Abstract

Background Mental stress (MS) triggers myocardial ischaemia at cardiac workloads that are lower than those that cause exercise-induced ischaemia in the same patient. Methods Intracoronary pressure and flow velocity data were acquired from 15 CAD (FFR 70% stenosis) patients and 11 controls during MS (mental arithmetic, stroop test). 7 CAD patients and 5 controls also underwent cycle ergometer exercise stress (ES). Coronary flow average peak velocity (APV), microvascular resistance (MR) and Buckberg index (BI) were calculated. Results At peak MS rate pressure product (RPP), a marker of myocardial oxygen demand, increased by 4418 ± 2353mmHg.bpm (p = 0 Conclusion A paradoxical rise in MR does occur in response to MS that is not seen with ES at similar workloads. This abnormal endothelial response correlates with the extent of atherosclerosis in the vessel.

Published
2016

5. Fractional Flow Reserve and The Instant Wave-free Ratio Have Equivalent Agreement with Flow Based Indices Across the Entire Spectrum of Stenosis Severity: Results of CLARIFY (The Classification Accuracy of Pressure-only Ratios Against Indices Using Flow Study)

Author

Jamil Mayet, Sayan Sen, Justin E. Davies, Alun D. Hughes, Kal Asrress, Darrel P. Francis, Javier Escaned, Christopher Baker, Ghada Mikhail, Ricardo Petraco, Sukhjinder Nijjer, Rodney A. Foale, Amarjit Sethi, Simon Redwood, and Iqbal S. Malik

Subjects
medicine.medical_specialty, business.industry, Spectrum (functional analysis), Mathematical analysis, Fractional flow reserve, medicine.disease, Stenosis, Flow (mathematics), Internal medicine, Cardiology, Medicine, Cardiology and Cardiovascular Medicine, business, Instant
Published
2013

6. FRACTIONAL FLOW RESERVE AND THE INSTANT WAVE–FREE RATIO HAVE EQUIVALENT AGREEMENT WITH FLOW–BASED INDICES ACROSS THE ENTIRE SPECTRUM OF STENOSIS SEVERITY RESULTS OF THE CLARIFY STUDY RESULTS OF CLARIFY (THE CLASSIFICATION ACCURACY OF PRESSURE–ONLY RATIOS AGAINST INDICES USING FLOW STUDY)

Author

Sayan Sen, Simon Redwood, Iqbal S. Malik, Alun D. Hughes, Jamil Mayet, Ghada W. Mikhail, Darrel P. Francis, Sukhjinder Nijjer, Kal Asrress, Rodney A. Foale, Javier Escaned, Justin E. Davies, and Ricardo Petraco da Cunha

Subjects
Stenosis, Flow (mathematics), business.industry, Mathematical analysis, Spectrum (functional analysis), medicine, Fractional flow reserve, Cardiology and Cardiovascular Medicine, medicine.disease, business, Instant
Published
2013

Catalog

Books, media, physical & digital resources
See catalog results