Umar aziz khan - Academia.edu (original) (raw)
Papers by Umar aziz khan
Anaesthesia, 1986
A case is presented in which the inhalation OJ* a foreign body caused a respiratory arrest and wa... more A case is presented in which the inhalation OJ* a foreign body caused a respiratory arrest and was subsequently diagnosed and treated as an attack ofacute asthma. Thepresentation, diagnosis. investigation and treutment of this condition is discussed and a review of the literature is presented.
Echocardiography (Mount Kisco, N.Y.), Jan 27, 2017
To assess the effects of submassive pulmonary embolism (SMPE) on right atrial (RA) anatomy and fu... more To assess the effects of submassive pulmonary embolism (SMPE) on right atrial (RA) anatomy and function. Right ventricular dysfunction (RVD) is associated with adverse outcomes in SMPE. However, the effects of SMPE on the structure and function of the RA have received much less attention. Fifty patients with SMPE documented by CT angiography (SMPE group) and evidence of RVD on two-dimensional echocardiography were retrospectively identified and compared to 50 controls (control group). Both RA and RV areas, volumes and fractional area change (FAC) were measured. Pulmonary artery systolic pressures were estimated. RA and RV longitudinal strains were obtained using vector velocity imaging (VVI). Compared with controls, RA and RV FACs were significantly reduced and associated with higher chamber volumes in the SMPE group. Global longitudinal RA strain was reduced in the SMPE group (29% + 11% vs 55% + 16%; P < .01), as was global RV longitudinal strain (-12% + 5% vs -20% + 5%, P < ...
Current Heart Failure Reports, 2012
Several new imaging modalities are being utilized in the management of heart failure. Echocardiog... more Several new imaging modalities are being utilized in the management of heart failure. Echocardiography and speckle tracking imaging offer clinician the benefits of easy accessibility, real time data interpretation and objective quantification of heart function. Accordingly, this article reviews the current evidence base related to the use of echocardiography and other advanced ultrasonography techniques in heart failure, and discusses applications as well as limitations of these emerging technologies. The role of cardiac resynchronization therapy (CRT) and implications of the PROSPECT (Predictors of Response to CRT) trial in management of heart failure are also reviewed. The article concludes with a discussion about the evolving role of echocardiography in diagnosis and management of subclinical heart disease, so that preventive strategies may be devised.
Echocardiography, 2000
Two-dimensional speckle tracking imaging (STI) has recently been applied to the study of left atr... more Two-dimensional speckle tracking imaging (STI) has recently been applied to the study of left atrial (LA) reservoir function. We utilized STI to analyze LA function in diastolic dysfunction (DD), hypothesizing that LA strain abnormality is part of the pathogenesis of diastolic dysfunction. We applied STI to 50 patients with Grade 1-2 DD, comparing these results to 100 normal controls. Complete Doppler analysis of filling was made using peak E, peak A and tissue Doppler e&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; velocities; E/e&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; was used as a surrogate for LA pressure and LA stiffness index was calculated. In analysis of covariance, adjusting for age and gender, compared with controls, DD patients had higher E/e&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;, greater LA volume and greater LA stiffness, but lower E/A ratio and global LA strain. LA strain appears to be inversely related to LA volume, but not to other indices of LV diastolic function. In subgroup analysis, LA strain was significantly lower, and stiffness significantly higher in DD, even after correction for differences in LA volume and E/A ratio. Analysis of ROC curves suggests that abnormal LA strain is a better marker for diastolic dysfunction than LA enlargement. LA strain by STI is significantly reduced in early diastolic dysfunction and is related to higher LA stiffness and LA size. Reduction in LA strain is partially independent of LA volume; accordingly we hypothesize that reduced atrial strain indicates impaired atrial distensibility.
Cardiovascular Ultrasound, 2012
Background Echocardiographic left atrial (LA) strain parameters have been associated with atrial ... more Background Echocardiographic left atrial (LA) strain parameters have been associated with atrial fibrillation (AF) in prior studies. Our goal was to determine if strain measures [peak systolic longitudinal strain (LAS) and stiffness index (LASt)] changed after cardioversion (CV); and their relation to AF recurrence. Methods and results 46 participants with persistent AF and 41 age-matched participants with no AF were recruited. LAS and LASt were measured before and immediately after CV using 2D speckle tracking imaging (2DSI). Maintenance of sinus rhythm was assessed over a 6-month follow up. Mean LAS was lower, and mean LASt higher, in participants with AF before CV as compared to control group (11.9 ± 1.0 vs 35.7 ± 1.7, p<0.01 and 1.31 ± 0.17 vs 0.23 ± 0.01, p<0.01, respectively). There was an increase in the mean LAS immediately after CV (11.9 ± 1.0 vs 15.9 ± 1.3, p<0.01), whereas mean LASt did not change significantly after CV (p=0.62). Although neither LAS nor LASt wer...
2013 19th International Conference on Automation and Computing, Sep 1, 2013
This contribution reports a method for increasing the imaging speed of an Atomic Force Microscope... more This contribution reports a method for increasing the imaging speed of an Atomic Force Microscope. The is done by allowing the complete length of the cantilever beam to interact with the sample surface rather than just the free end. The deflection of the beam is then observed at uniformly distributed points along the beam length using an array of laser spots and detectors. This scheme enables measurement of an entire line on the sample surface simultaneously, thus eliminating the need for rastering and reducing imaging time. This speed up is illustrated in this contribution through simulation results.
Anaesthesia, 1986
A case is presented in which the inhalation OJ* a foreign body caused a respiratory arrest and wa... more A case is presented in which the inhalation OJ* a foreign body caused a respiratory arrest and was subsequently diagnosed and treated as an attack ofacute asthma. Thepresentation, diagnosis. investigation and treutment of this condition is discussed and a review of the literature is presented.
Echocardiography (Mount Kisco, N.Y.), Jan 27, 2017
To assess the effects of submassive pulmonary embolism (SMPE) on right atrial (RA) anatomy and fu... more To assess the effects of submassive pulmonary embolism (SMPE) on right atrial (RA) anatomy and function. Right ventricular dysfunction (RVD) is associated with adverse outcomes in SMPE. However, the effects of SMPE on the structure and function of the RA have received much less attention. Fifty patients with SMPE documented by CT angiography (SMPE group) and evidence of RVD on two-dimensional echocardiography were retrospectively identified and compared to 50 controls (control group). Both RA and RV areas, volumes and fractional area change (FAC) were measured. Pulmonary artery systolic pressures were estimated. RA and RV longitudinal strains were obtained using vector velocity imaging (VVI). Compared with controls, RA and RV FACs were significantly reduced and associated with higher chamber volumes in the SMPE group. Global longitudinal RA strain was reduced in the SMPE group (29% + 11% vs 55% + 16%; P < .01), as was global RV longitudinal strain (-12% + 5% vs -20% + 5%, P < ...
Current Heart Failure Reports, 2012
Several new imaging modalities are being utilized in the management of heart failure. Echocardiog... more Several new imaging modalities are being utilized in the management of heart failure. Echocardiography and speckle tracking imaging offer clinician the benefits of easy accessibility, real time data interpretation and objective quantification of heart function. Accordingly, this article reviews the current evidence base related to the use of echocardiography and other advanced ultrasonography techniques in heart failure, and discusses applications as well as limitations of these emerging technologies. The role of cardiac resynchronization therapy (CRT) and implications of the PROSPECT (Predictors of Response to CRT) trial in management of heart failure are also reviewed. The article concludes with a discussion about the evolving role of echocardiography in diagnosis and management of subclinical heart disease, so that preventive strategies may be devised.
Echocardiography, 2000
Two-dimensional speckle tracking imaging (STI) has recently been applied to the study of left atr... more Two-dimensional speckle tracking imaging (STI) has recently been applied to the study of left atrial (LA) reservoir function. We utilized STI to analyze LA function in diastolic dysfunction (DD), hypothesizing that LA strain abnormality is part of the pathogenesis of diastolic dysfunction. We applied STI to 50 patients with Grade 1-2 DD, comparing these results to 100 normal controls. Complete Doppler analysis of filling was made using peak E, peak A and tissue Doppler e&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; velocities; E/e&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; was used as a surrogate for LA pressure and LA stiffness index was calculated. In analysis of covariance, adjusting for age and gender, compared with controls, DD patients had higher E/e&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;, greater LA volume and greater LA stiffness, but lower E/A ratio and global LA strain. LA strain appears to be inversely related to LA volume, but not to other indices of LV diastolic function. In subgroup analysis, LA strain was significantly lower, and stiffness significantly higher in DD, even after correction for differences in LA volume and E/A ratio. Analysis of ROC curves suggests that abnormal LA strain is a better marker for diastolic dysfunction than LA enlargement. LA strain by STI is significantly reduced in early diastolic dysfunction and is related to higher LA stiffness and LA size. Reduction in LA strain is partially independent of LA volume; accordingly we hypothesize that reduced atrial strain indicates impaired atrial distensibility.
Cardiovascular Ultrasound, 2012
Background Echocardiographic left atrial (LA) strain parameters have been associated with atrial ... more Background Echocardiographic left atrial (LA) strain parameters have been associated with atrial fibrillation (AF) in prior studies. Our goal was to determine if strain measures [peak systolic longitudinal strain (LAS) and stiffness index (LASt)] changed after cardioversion (CV); and their relation to AF recurrence. Methods and results 46 participants with persistent AF and 41 age-matched participants with no AF were recruited. LAS and LASt were measured before and immediately after CV using 2D speckle tracking imaging (2DSI). Maintenance of sinus rhythm was assessed over a 6-month follow up. Mean LAS was lower, and mean LASt higher, in participants with AF before CV as compared to control group (11.9 ± 1.0 vs 35.7 ± 1.7, p<0.01 and 1.31 ± 0.17 vs 0.23 ± 0.01, p<0.01, respectively). There was an increase in the mean LAS immediately after CV (11.9 ± 1.0 vs 15.9 ± 1.3, p<0.01), whereas mean LASt did not change significantly after CV (p=0.62). Although neither LAS nor LASt wer...
2013 19th International Conference on Automation and Computing, Sep 1, 2013
This contribution reports a method for increasing the imaging speed of an Atomic Force Microscope... more This contribution reports a method for increasing the imaging speed of an Atomic Force Microscope. The is done by allowing the complete length of the cantilever beam to interact with the sample surface rather than just the free end. The deflection of the beam is then observed at uniformly distributed points along the beam length using an array of laser spots and detectors. This scheme enables measurement of an entire line on the sample surface simultaneously, thus eliminating the need for rastering and reducing imaging time. This speed up is illustrated in this contribution through simulation results.