David Sahn - Academia.edu (original) (raw)

Papers by David Sahn

The American Journal of Cardiology, 1999

Atrial fibrillation is the most common sustained arrhythmia that now affects approximately 2.2 mi... more Atrial fibrillation is the most common sustained arrhythmia that now affects approximately 2.2 million adults in the United States alone. Minimally invasive catheter-based electrophysiological interventions have revolutionized the management of cardiac arrhythmias. We are developing forward-viewing ultrasound imaging catheters based on two types of transducer arrays using the capacitive micromachined ultrasonic transducer technology: A 10-MHz, 24-element MicroLinear (ML) array with

The American Journal of Cardiology, Dec 1, 1983

Journal of the American College of Cardiology, 1997

Objectives. The aim of the present study was to quantitate aortic regurgitant volume and regurgit... more Objectives. The aim of the present study was to quantitate aortic regurgitant volume and regurgitant fraction in a chronic animal model with surgically created aortic regurgitation using a new semiautomated color Doppler flow calculation method.

Circulation, Nov 20, 2012

Circulation, Nov 22, 2011

We tested a newly developed 4-dimensional (4D) right ventricular (RV) analysis method for computi... more We tested a newly developed 4-dimensional (4D) right ventricular (RV) analysis method for computing RV volumes for both 3-dimensional (3D) ultrasound (US) and magnetic resonance (MR) images.

BioMed Research International, 2015

Left atrial (LA) functional analysis has an established role in assessing left ventricular diasto... more Left atrial (LA) functional analysis has an established role in assessing left ventricular diastolic function. The current standard echocardiographic parameters used to study left ventricular diastolic function include pulsed-wave Doppler mitral inflow analysis, tissue Doppler imaging measurements, and LA dimension estimation. However, the above-mentioned parameters do not directly quantify LA performance. Deformation studies using strain and strain-rate imaging to assess LA function were validated in previous research, but this technique is not currently used in routine clinical practice. This review discusses the history, importance, and pitfalls of strain technology for the analysis of LA mechanics.

Lecture Notes in Computer Science, 2009

Automated motion tracking of the myocardium from 3D echocardiography provides insight into heart'... more Automated motion tracking of the myocardium from 3D echocardiography provides insight into heart's architecture and function. We present a method for 3D cardiac motion tracking using nonrigid image registration. Our contribution is two-fold. We introduce a new similarity measure derived from a maximum likelihood perspective taking into account physical properties of ultrasound image acquisition and formation. Second, we use envelope-detected 3D echo images in the raw spherical coordinates format, which preserves speckle statistics and represents a compromise between signal detail and data complexity. We derive mechanical measures such as strain and twist, and validate using sonomicrometry in open-chest piglets. The results demonstrate the accuracy and feasibility of our method for studying cardiac motion.

2007 IEEE Conference on Computer Vision and Pattern Recognition, 2007

Tracking of speckles in echocardiography enables the study of myocardium deformation, and thus ca... more Tracking of speckles in echocardiography enables the study of myocardium deformation, and thus can provide insights about heart structure and function. Most of the current methods are based on 2D speckle tracking, which suffers from errors due to through-plane decorrelation. Speckle tracking in 3D overcomes such limitation. However, 3D speckle tracking is a challenging problem due to relatively low spatial and temporal resolution of 3D echocardiography. To ensure accurate and robust tracking, high level spatial and temporal constraints need to be incorporated. In this paper, we introduce a novel method for speckle tracking in 3D echocardiography. Instead of tracking each speckle independently, we enforce a motion coherence constraint, in conjunction with a dynamic model for the speckles. This method is validated on in vivo porcine hearts, and is proved to be accurate and robust.

International Journal of Cardiology, 2015

The adoption of electronic health records (EHR) has created an opportunity for multicenter data c... more The adoption of electronic health records (EHR) has created an opportunity for multicenter data collection, yet the feasibility and reliability of this methodology is unknown. The aim of this study was to integrate EHR data into a homogeneous central repository specifically addressing the field of adult congenital heart disease (ACHD). Target data variables were proposed and prioritized by consensus of investigators at five target ACHD programs. Database analysts determined which variables were available within their institutions' EHR and stratified their accessibility, and results were compared between centers. Data for patients seen in a single calendar year were extracted to a uniform database and subsequently consolidated. From 415 proposed target variables, only 28 were available in discrete formats at all centers. For variables of highest priority, 16/28 (57%) were available at all four sites, but only 11% for those of high priority. Integration was neither simple nor straightforward. Coding schemes in use for congenital heart diagnoses varied and would require additional user input for accurate mapping. There was considerable variability in procedure reporting formats and medication schemes, often with center-specific modifications. Despite the challenges, the final acquisition included limited data on 2161 patients, and allowed for population analysis of race/ethnicity, defect complexity, and body morphometrics. Large-scale multicenter automated data acquisition from EHRs is feasible yet challenging. Obstacles stem from variability in data formats, coding schemes, and adoption of non-standard lists within each EHR. The success of large-scale multicenter ACHD research will require institution-specific data integration efforts.

Ultrasound in Medicine & Biology, 2008

Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2013

Quantitative motion analysis from cardiac imaging is important to study the function of heart. Mo... more Quantitative motion analysis from cardiac imaging is important to study the function of heart. Most of existing image-based motion estimation methods model the myocardium as an isotropically elastic continuum. We propose a novel anisotropic regularization method which enforces the transmural homogeneity of the strain along myofiber. The myofiber orientation in the end-diastolic frame is obtained by registering it with a diffusion tensor atlas. Our method is formulated in a diffeomorphic registration framework, and tested on multimodal cardiac image sequences of two subjects using 3D echocardiography and cine and tagged MRI. Results show that the estimated transformations in our method are more smooth and more accurate than those in isotropic regularization.

Cardiology in the Young, 2015

To quantify myocardial blood flow in infants and children with mild or moderate aortic stenosis u... more To quantify myocardial blood flow in infants and children with mild or moderate aortic stenosis using adenosine-infusion cardiac magnetic resonance. It is unclear whether asymptomatic children with mild/moderate aortic stenosis have myocardial abnormalities. In addition, cardiac magnetic resonance-determined normative myocardial blood flow data in children have not been reported. We studied 31 infants and children with either haemodynamically normal hearts (n=20, controls) or mild/moderate aortic stenosis (n=11). The left ventricular myocardium was divided into six segments, and the change in average segmental signal intensity during contrast transit was used to quantify absolute flow (ml/g/minute) at rest and during adenosine infusion by deconvolution of the tissue curves with the arterial input of contrast. In all the cases, adenosine was well tolerated without complications. The mean pressure gradient between the left ventricle and the ascending aorta was higher in the aortic stenosis group compared with controls (24 versus 3 mmHg, p<0.001). Left ventricular wall mass was slightly higher in the aortic stenosis group compared with controls (65 versus 50 g/m2, p<0.05). After adenosine treatment, both the absolute increase in myocardial blood flow (p<0.0001) and the hyperaemic flow significantly decreased (p<0.001) in children with mild/moderate aortic stenosis compared with controls. Abnormal myocardial blood flow in children with mild/moderate aortic stenosis may be an important therapeutic target.

Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2007

Automated motion reconstruction of the left ventricle (LV) from 3D echocardiography provides insi... more Automated motion reconstruction of the left ventricle (LV) from 3D echocardiography provides insight into myocardium architecture and function. Low image quality and artifacts make 3D ultrasound image processing a challenging problem. We introduce a LV tracking method, which combines textural and structural information to overcome the image quality limitations. Our method automatically reconstructs the motion of the LV contour (endocardium and epicardium) from a sequence of 3D ultrasound images.

Cardiology clinics, 2007

Three-dimensional (3D) ultrasound of the fetal heart is increasingly being used in prenatal diagn... more Three-dimensional (3D) ultrasound of the fetal heart is increasingly being used in prenatal diagnosis. While very detailed fetal cardiac studies can be performed using the various 3D ultrasound modalities, their utility for screening for fetal heart disease is yet to be proven. With the emergence of even newer technologies such as quantification techniques and two-dimensional matrix arrays, further improvements are imminent.

Current treatment options in cardiovascular medicine, 2000

Endocarditis is a rare, but potentially fatal process in children. Patients with congenital heart... more Endocarditis is a rare, but potentially fatal process in children. Patients with congenital heart disease compose the majority of patients with endocarditis. Neonates and children with central venous catheters are an increasingly frequent group of patients diagnose with this disease. Rheumatic fever predisposing to endocarditis is unusual. Streptococcus viridans and Staphylococcus aureus are the most pervasive organisms associated with endocarditis, though others are becoming more frequent. Blood cultures should be obtained in febrile children with congenital heart disease before the administration of antibiotics. Echocardiography is useful in children with known endocarditis, and in children in whom there is a high level of clinical suspicion for endocarditis. Echocardiography is a poor screening tool for patients without clinical or bacteriologic evidence for endocarditis. Endocarditis prophylaxis for children with congenital heart disease (excluding a secundum atrial septal defec...

Journal of Tongji Medical University = Tong ji yi ke da xue xue bao, 1993

Nyquist velocity and transorifice pressure gradient dramatically influence color aliasing shape a... more Nyquist velocity and transorifice pressure gradient dramatically influence color aliasing shape and accuracy of simple hemispherical flow convergence equation for calculation of flow rate. The present in vitro study was performed to determine whether the value of Nyquist velocity, at which the shape of proximal isovelocity surface is best fit for a given shape assumption in different orifice size, and the flow rate may be a determinable and orifice size independent function of clinically measurable peak velocity or transorifice pressure gradient. Steady flow was driven through circular discrete orifices with diameter of 3.8 mm, 5.5 mm and 10 mm and flow rate ranging from 2.88 L/min to 8.28 L/min. For every flow rate, Doppler color encoded M-mode images through the center of flow convergence region were transferred into the microcomputer in their original digital format. The continuous wave Doppler traces of maximal velocity through the orifice were performed for the calculation of p...

The American Journal of Cardiology, 1999

Atrial fibrillation is the most common sustained arrhythmia that now affects approximately 2.2 mi... more Atrial fibrillation is the most common sustained arrhythmia that now affects approximately 2.2 million adults in the United States alone. Minimally invasive catheter-based electrophysiological interventions have revolutionized the management of cardiac arrhythmias. We are developing forward-viewing ultrasound imaging catheters based on two types of transducer arrays using the capacitive micromachined ultrasonic transducer technology: A 10-MHz, 24-element MicroLinear (ML) array with

The American Journal of Cardiology, Dec 1, 1983

Journal of the American College of Cardiology, 1997

Objectives. The aim of the present study was to quantitate aortic regurgitant volume and regurgit... more Objectives. The aim of the present study was to quantitate aortic regurgitant volume and regurgitant fraction in a chronic animal model with surgically created aortic regurgitation using a new semiautomated color Doppler flow calculation method.

Circulation, Nov 20, 2012

Circulation, Nov 22, 2011

We tested a newly developed 4-dimensional (4D) right ventricular (RV) analysis method for computi... more We tested a newly developed 4-dimensional (4D) right ventricular (RV) analysis method for computing RV volumes for both 3-dimensional (3D) ultrasound (US) and magnetic resonance (MR) images.

BioMed Research International, 2015

Left atrial (LA) functional analysis has an established role in assessing left ventricular diasto... more Left atrial (LA) functional analysis has an established role in assessing left ventricular diastolic function. The current standard echocardiographic parameters used to study left ventricular diastolic function include pulsed-wave Doppler mitral inflow analysis, tissue Doppler imaging measurements, and LA dimension estimation. However, the above-mentioned parameters do not directly quantify LA performance. Deformation studies using strain and strain-rate imaging to assess LA function were validated in previous research, but this technique is not currently used in routine clinical practice. This review discusses the history, importance, and pitfalls of strain technology for the analysis of LA mechanics.

Lecture Notes in Computer Science, 2009

Automated motion tracking of the myocardium from 3D echocardiography provides insight into heart'... more Automated motion tracking of the myocardium from 3D echocardiography provides insight into heart's architecture and function. We present a method for 3D cardiac motion tracking using nonrigid image registration. Our contribution is two-fold. We introduce a new similarity measure derived from a maximum likelihood perspective taking into account physical properties of ultrasound image acquisition and formation. Second, we use envelope-detected 3D echo images in the raw spherical coordinates format, which preserves speckle statistics and represents a compromise between signal detail and data complexity. We derive mechanical measures such as strain and twist, and validate using sonomicrometry in open-chest piglets. The results demonstrate the accuracy and feasibility of our method for studying cardiac motion.

2007 IEEE Conference on Computer Vision and Pattern Recognition, 2007

Tracking of speckles in echocardiography enables the study of myocardium deformation, and thus ca... more Tracking of speckles in echocardiography enables the study of myocardium deformation, and thus can provide insights about heart structure and function. Most of the current methods are based on 2D speckle tracking, which suffers from errors due to through-plane decorrelation. Speckle tracking in 3D overcomes such limitation. However, 3D speckle tracking is a challenging problem due to relatively low spatial and temporal resolution of 3D echocardiography. To ensure accurate and robust tracking, high level spatial and temporal constraints need to be incorporated. In this paper, we introduce a novel method for speckle tracking in 3D echocardiography. Instead of tracking each speckle independently, we enforce a motion coherence constraint, in conjunction with a dynamic model for the speckles. This method is validated on in vivo porcine hearts, and is proved to be accurate and robust.

International Journal of Cardiology, 2015

The adoption of electronic health records (EHR) has created an opportunity for multicenter data c... more The adoption of electronic health records (EHR) has created an opportunity for multicenter data collection, yet the feasibility and reliability of this methodology is unknown. The aim of this study was to integrate EHR data into a homogeneous central repository specifically addressing the field of adult congenital heart disease (ACHD). Target data variables were proposed and prioritized by consensus of investigators at five target ACHD programs. Database analysts determined which variables were available within their institutions' EHR and stratified their accessibility, and results were compared between centers. Data for patients seen in a single calendar year were extracted to a uniform database and subsequently consolidated. From 415 proposed target variables, only 28 were available in discrete formats at all centers. For variables of highest priority, 16/28 (57%) were available at all four sites, but only 11% for those of high priority. Integration was neither simple nor straightforward. Coding schemes in use for congenital heart diagnoses varied and would require additional user input for accurate mapping. There was considerable variability in procedure reporting formats and medication schemes, often with center-specific modifications. Despite the challenges, the final acquisition included limited data on 2161 patients, and allowed for population analysis of race/ethnicity, defect complexity, and body morphometrics. Large-scale multicenter automated data acquisition from EHRs is feasible yet challenging. Obstacles stem from variability in data formats, coding schemes, and adoption of non-standard lists within each EHR. The success of large-scale multicenter ACHD research will require institution-specific data integration efforts.

Ultrasound in Medicine & Biology, 2008

Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2013

Quantitative motion analysis from cardiac imaging is important to study the function of heart. Mo... more Quantitative motion analysis from cardiac imaging is important to study the function of heart. Most of existing image-based motion estimation methods model the myocardium as an isotropically elastic continuum. We propose a novel anisotropic regularization method which enforces the transmural homogeneity of the strain along myofiber. The myofiber orientation in the end-diastolic frame is obtained by registering it with a diffusion tensor atlas. Our method is formulated in a diffeomorphic registration framework, and tested on multimodal cardiac image sequences of two subjects using 3D echocardiography and cine and tagged MRI. Results show that the estimated transformations in our method are more smooth and more accurate than those in isotropic regularization.

Cardiology in the Young, 2015

To quantify myocardial blood flow in infants and children with mild or moderate aortic stenosis u... more To quantify myocardial blood flow in infants and children with mild or moderate aortic stenosis using adenosine-infusion cardiac magnetic resonance. It is unclear whether asymptomatic children with mild/moderate aortic stenosis have myocardial abnormalities. In addition, cardiac magnetic resonance-determined normative myocardial blood flow data in children have not been reported. We studied 31 infants and children with either haemodynamically normal hearts (n=20, controls) or mild/moderate aortic stenosis (n=11). The left ventricular myocardium was divided into six segments, and the change in average segmental signal intensity during contrast transit was used to quantify absolute flow (ml/g/minute) at rest and during adenosine infusion by deconvolution of the tissue curves with the arterial input of contrast. In all the cases, adenosine was well tolerated without complications. The mean pressure gradient between the left ventricle and the ascending aorta was higher in the aortic stenosis group compared with controls (24 versus 3 mmHg, p<0.001). Left ventricular wall mass was slightly higher in the aortic stenosis group compared with controls (65 versus 50 g/m2, p<0.05). After adenosine treatment, both the absolute increase in myocardial blood flow (p<0.0001) and the hyperaemic flow significantly decreased (p<0.001) in children with mild/moderate aortic stenosis compared with controls. Abnormal myocardial blood flow in children with mild/moderate aortic stenosis may be an important therapeutic target.

Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2007

Automated motion reconstruction of the left ventricle (LV) from 3D echocardiography provides insi... more Automated motion reconstruction of the left ventricle (LV) from 3D echocardiography provides insight into myocardium architecture and function. Low image quality and artifacts make 3D ultrasound image processing a challenging problem. We introduce a LV tracking method, which combines textural and structural information to overcome the image quality limitations. Our method automatically reconstructs the motion of the LV contour (endocardium and epicardium) from a sequence of 3D ultrasound images.

Cardiology clinics, 2007

Three-dimensional (3D) ultrasound of the fetal heart is increasingly being used in prenatal diagn... more Three-dimensional (3D) ultrasound of the fetal heart is increasingly being used in prenatal diagnosis. While very detailed fetal cardiac studies can be performed using the various 3D ultrasound modalities, their utility for screening for fetal heart disease is yet to be proven. With the emergence of even newer technologies such as quantification techniques and two-dimensional matrix arrays, further improvements are imminent.

Current treatment options in cardiovascular medicine, 2000

Endocarditis is a rare, but potentially fatal process in children. Patients with congenital heart... more Endocarditis is a rare, but potentially fatal process in children. Patients with congenital heart disease compose the majority of patients with endocarditis. Neonates and children with central venous catheters are an increasingly frequent group of patients diagnose with this disease. Rheumatic fever predisposing to endocarditis is unusual. Streptococcus viridans and Staphylococcus aureus are the most pervasive organisms associated with endocarditis, though others are becoming more frequent. Blood cultures should be obtained in febrile children with congenital heart disease before the administration of antibiotics. Echocardiography is useful in children with known endocarditis, and in children in whom there is a high level of clinical suspicion for endocarditis. Echocardiography is a poor screening tool for patients without clinical or bacteriologic evidence for endocarditis. Endocarditis prophylaxis for children with congenital heart disease (excluding a secundum atrial septal defec...

Journal of Tongji Medical University = Tong ji yi ke da xue xue bao, 1993

Nyquist velocity and transorifice pressure gradient dramatically influence color aliasing shape a... more Nyquist velocity and transorifice pressure gradient dramatically influence color aliasing shape and accuracy of simple hemispherical flow convergence equation for calculation of flow rate. The present in vitro study was performed to determine whether the value of Nyquist velocity, at which the shape of proximal isovelocity surface is best fit for a given shape assumption in different orifice size, and the flow rate may be a determinable and orifice size independent function of clinically measurable peak velocity or transorifice pressure gradient. Steady flow was driven through circular discrete orifices with diameter of 3.8 mm, 5.5 mm and 10 mm and flow rate ranging from 2.88 L/min to 8.28 L/min. For every flow rate, Doppler color encoded M-mode images through the center of flow convergence region were transferred into the microcomputer in their original digital format. The continuous wave Doppler traces of maximal velocity through the orifice were performed for the calculation of p...