Amer M. Johri
Queen's University
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Featured researches published by Amer M. Johri.
Jacc-cardiovascular Imaging | 2011
Amer M. Johri; Michael H. Picard; John B. Newell; Jane E. Marshall; Mary Etta King; Judy Hung
OBJECTIVES This study sought to determine whether a formalized teaching intervention could reduce the interobserver variability (IOV) in visual estimation of left ventricular ejection fraction (LVEF) within a group of sonographers and physicians with a spectrum of experience. BACKGROUND Precise and reliable echocardiographic assessment of LVEF is necessary for clinical decision-making and minimizing duplicative testing. Skill in the visual estimation of LVEF varies depending on experience and is critical for corroborating EF quantification. IOV may also lead to inconsistency if multiple readers are assessing the EF on serial exams. METHODS Fourteen cases of 2-dimensional echocardiograms were shown to 25 participants who estimated the EF based on a complete assessment of LV wall motion including parasternal, short-axis, apical, and subcostal views. The cases represented a spectrum of EF range, image quality, and clinical context. Following the initial interpretations, participants underwent a teaching intervention involving tutorial review of reference cases and group discussion of each case with determination of the EF guided by quantitative measure (biplane Simpson method). Three months after the teaching intervention, 14 new cases were shown to the 25 participants following the same methodology. RESULTS IOV was quantified before and after the teaching intervention with the use of a 3-factor, nested analysis of variance. The factors were: observer, patient, and pre- and post-intervention (time). The analysis of variance showed that the intervention reduced the IOV for the 25 readers between the pre- and post-intervention assessments (F = 2.8, p = 0.007). The IOV decreased from ± 14% EF prior to intervention to ± 8.4% EF following intervention (a 40% reduction in IOV). CONCLUSIONS In a large echocardiography laboratory with a wide range of training levels and experience, a simple, formalized teaching intervention can successfully diminish IOV of LVEF assessment. This intervention provides not only discrete quality measures, but also serves as a practical tool to document and improve quality of reporting, potentially reducing clinical inefficiencies and repeat testing.
Canadian Journal of Cardiology | 2015
John J. Ryan; Jessica Huston; Shelby Kutty; Nathan Hatton; Lindsay C. Bowman; Lian Tian; Julia E. Herr; Amer M. Johri; Stephen L. Archer
Pulmonary arterial hypertension (PAH) is an obstructive pulmonary vasculopathy, characterized by excess proliferation, apoptosis resistance, inflammation, fibrosis, and vasoconstriction. Although PAH therapies target some of these vascular abnormalities (primarily vasoconstriction), most do not directly benefit the right ventricle (RV). This is suboptimal because a patients functional state and prognosis are largely determined by the success of the adaptation of the RV to the increased afterload. The RV initially hypertrophies but might ultimately decompensate, becoming dilated, hypokinetic, and fibrotic. A number of pathophysiologic abnormalities have been identified in the PAH RV, including: ischemia and hibernation (partially reflecting RV capillary rarefaction), autonomic activation (due to G protein receptor kinase 2-mediated downregulation and desensitization of β-adrenergic receptors), mitochondrial-metabolic abnormalities (notably increased uncoupled glycolysis and glutaminolysis), and fibrosis. Many RV abnormalities are detectable using molecular imaging and might serve as biomarkers. Some molecular pathways, such as those regulating angiogenesis, metabolism, and mitochondrial dynamics, are similarly deranged in the RV and pulmonary vasculature, offering the possibility of therapies that treat the RV and pulmonary circulation. An important paradigm in PAH is that the RV and pulmonary circulation constitute a unified cardiopulmonary unit. Clinical trials of PAH pharmacotherapies should assess both components of the cardiopulmonary unit.
Journal of The American Society of Echocardiography | 2014
Thomas R. Cawthorn; Curtis Nickel; Michael O'Reilly; Henryk Kafka; James W. Tam; Lynel C. Jackson; Anthony J. Sanfilippo; Amer M. Johri
BACKGROUND Handheld ultrasound is emerging as an important tool for point-of-care cardiac assessment. Although cardiac ultrasound skills are traditionally introduced during postgraduate training, the optimal time and methodology to initiate training in focused cardiac ultrasound (FCU) are unknown. The objective of this study was to develop and evaluate a novel curriculum for training medical students in the use of FCU. METHODS The study was conducted in two phases. In the first phase, 12 first-year medical students underwent FCU training over an 8-week period. In the second phase, 45 third-year medical students were randomized to one of three educational programs. Program 1 consisted of a lecture-based approach with scan training by a sonographer. Program 2 coupled electronic education modules with sonographer scan training. Program 3 was fully self-directed, combining electronic modules with scan training on a high-fidelity ultrasound simulator. Image interpretation skills and scanning technique were evaluated after each program. RESULTS First-year medical students were able to modestly improve interpretation ability and acquire limited scanning skills. Third-year medical students exhibited similar improvement in mean examination score for image interpretation whether a lecture-based program or electronic modules was used. Students in the self-directed group using an ultrasound simulator had significantly lower mean quality scores than students taught by sonographers. CONCLUSIONS Third-year medical students were able to acquire FCU image acquisition and interpretation skills after a novel training program. Self-directed electronic modules are effective for teaching introductory FCU interpretation skills, while expert-guided training is important for developing scanning technique.
Journal of The American Society of Echocardiography | 2013
Amer M. Johri; David W. Chitty; M. Matangi; Paul Malik; Parvin Mousavi; Andrew Day; Matthew Gravett; Christopher S. Simpson
BACKGROUND Screening tools for the detection of coronary artery disease (CAD) are of considerable interest in light of skyrocketing risk factors. Recent work suggests that carotid plaque has a relatively unexplored role in CAD risk prediction but has previously been limited by the difficulty in quantifying its irregular architecture using two-dimensional (2D) ultrasound. The aim of this study was to investigate the utility of a novel automated three-dimensional (3D) ultrasound-based carotid plaque volume quantification technique as a negative predictor of CAD. METHODS In this prospective study, 70 consecutive patients referred for coronary angiography underwent same-day 2D and 3D carotid ultrasound scans for the purpose of plaque quantification in the carotid bulbs. Two-dimensional plaque thickness was measured in its maximal value perpendicular to the vessel wall. Total 3D plaque volume was quantified using a stacked-contour method. Luminal narrowing of coronary arteries was analyzed using the established 16-segment model for coronary arteries to produce an overall angiographic score. Receiver operating characteristic curves, negative predictive value, and sensitivity of 2D and 3D plaque quantification relative to coronary angiography were determined. RESULTS The novel 3D carotid ultrasound method resulted in a higher negative predictive value and sensitivity relative to 2D carotid ultrasound at their optimal thresholds as determined by Youden indices of receiver operating characteristic curves. In particular, total 3D plaque volumes less than the threshold of 0.09 mL accurately predicted the absence of significant CAD in 93.3% of patients (98.0% sensitivity), whereas maximal 2D plaque thickness less than the threshold of 1.35 mm provided significantly lower negative predictability at 75% (93.9% sensitivity). CONCLUSIONS Using the determined threshold of 0.09 mL for plaque volumes, this feasibility study suggests that automated 3D ultrasound-based carotid plaque quantification may serve as an important clinical screening tool to help identify patients who are at low risk for significant CAD.
Circulation | 2008
Kibar Yared; Amer M. Johri; Anand Soni; Matthew J. Johnson; Tarik K. Alkasab; Ricardo C. Cury; Judy Hung; Wilfred Mamuya
A 59-year-old male was admitted to Massachusetts General Hospital, Boston, Mass, with a 2-month history of exertional dyspnea (New York Heart Association class II to III). The patient denied dyspnea at rest, chest pain, palpitations, or syncope. There was no history of fevers or recent weight loss. An outpatient echocardiogram (Figure 1), performed as part of the workup of the patient’s dyspnea, demonstrated normal left ventricular size and function. The right ventricle (RV) was normal in size but diffusely hypokinetic. There was evidence of segmental RV dysfunction, with 2 discrete aneurysmal areas in the RV free wall at the base and apex, which measured 1.5 and 3.0 cm in width. Both areas appeared thinned and dyskinetic. The echocardiographic appearance was suggestive of arrhythmogenic RV dysplasia/cardiomyopathy (ARVD/C).1 A CT scan ruled out the presence of pulmonary embolism but was notable for marked mediastinal lymphadenopathy (Figure 2 …
Nutrition Metabolism and Cardiovascular Diseases | 2014
Amer M. Johri; D.K. Heyland; Marie-France Hétu; Bredon Crawford; Spence Jd
As the incidence of metabolic syndrome increases, there is also a growing interest in finding safe and inexpensive treatments to help lower associated risk factors. L-carntine, a natural dietary supplement with the potential to ameliorate atherosclerosis, has been the subject of recent investigation and controversy. A majority of studies have shown benefit of L-C supplementation in the metabolic syndrome or cardiovascular risk factors. However, recent work has suggested that dietary L-C may accelerate atherosclerosis via gut microbiota metabolites, complicating the role of L-C supplementation in health.
Echocardiography-a Journal of Cardiovascular Ultrasound and Allied Techniques | 2011
Anand Jagannath; Amer M. Johri; Richard R. Liberthson; Marco Larobina; Jonathan Passeri; Dennis A. Tighe; Arvind K. Agnihotri
Quadricuspid aortic valve (QAV) is rare and its diagnosis, clinical course, and management are less well defined relative to other aortic valve abnormalities. Advances in diagnostic imaging, notably in ultrasound, have increased clinical awareness of this anomaly and prompted this review of our experience with 12 new patients and a compilation of previously reported patients to further characterize this condition. (Echocardiography 2011;28:1035‐1040)
Circulation-arrhythmia and Electrophysiology | 2012
Rodrigo Miranda; Michael A. Nault; Amer M. Johri; Christopher S. Simpson; Kevin A. Michael; Hoshiar Abdollah; Adrian Baranchuk; Damian P. Redfearn
Background—Cardiac resynchronization therapy is widely used for the treatment of heart failure. Recent data suggest that electric separation during left ventricular pacing varies within the right ventricle (RV). We hypothesized that placement of the RV lead guided by maximal electric separation (MES) would improve response to cardiac resynchronization therapy compared with standard apical placement. Methods and Results—A single-blind, randomized controlled trial was conducted. Patients eligible for cardiac resynchronization therapy-D were enrolled. Left ventricular lead placement was performed at the coronary sinus branch. The RV outflow tract, septum, and apex were mapped during left ventricular pacing and MES recorded. Patients were randomized to receive either apical placement or RV lead placement at the site mapping MES. Left ventricular ejection fraction, 6-minute walk distance, and New York Heart Association functional class were recorded at baseline and 3 months by blinded observers. Response was defined as at least one of the following: 5% absolute increase in ejection fraction, 50 m increase in 6-minute walk distance, or an increase by >1 functional class. Primary end point was improvement in ejection fraction at 3 months. Fifty patients were randomized (25 MES-guided and 25 apical). Baseline characteristics were similar in the 2 groups. Electric separation was lower in the apex (143±23 versus 168±25 ms in MES group; P=0.01). MES was most commonly septal and rarely apical (4/50 patients). Responders in the MES-guided versus apical group are as follows: Echo 21 versus 13 patients (P=0.032), 6-minute walk distance 19 versus 12 patients (P=0.079), and functional class 22 versus 15 patients (P=0.051). No dislodgment or reposition for suboptimal defibrillation tests was reported. Conclusions—MES-guided placement of the RV lead improves cardiac resynchronization therapy responders compared with standard apical placement.
Heart | 2010
Amer M. Johri; Jonathan Passeri; Michael H. Picard
Effective performance and interpretation of two dimensional (2D) echocardiography requires one to mentally integrate the collected images into a three dimensional (3D) reconstruction of the heart. For example, prolapse of the mitral leaflets may involve the entire leaflet, or only a leaflet portion, requiring the echocardiographer to examine each individual leaflet portion from a series of 2D images and then to mentally ‘map’ the valve to define the location and nature of the abnormality. To do this accurately, one must understand the relationship of each 2D image to one another. Quantification of cardiac structure and function by 2D echocardiography typically requires assumptions about the geometry of the structure being measured so that specific formulae can be accurately used. The shapes of these structures may become altered in various diseases and thus the geometric assumptions about shape become less accurate as do the values calculated from the formulae. 3D echocardiography eliminates the need for cognitive reconstruction of image planes and use of geometric assumptions about shape of structures for cardiac quantitation. This particularly applies to complex shapes such as the right ventricle, an aneurysmal left ventricle (LV), an asymmetrically stenotic or regurgitant valve orifice, eccentric regurgitant jets assessed by colour Doppler, valve annulae, and the complex structural relationships observed in congenital heart lesions. 3D echocardiography can be performed from the transthoracic or transoesophageal approach. The 3D echocardiographic technique has the potential to decrease the time required for complete image acquisition of the heart. Also, the 3D echocardiogram can be viewed from various projections by rotation of the images resulting in an improved appreciation of the relationships between various cardiac structures. Up until recently, 3D echocardiography was primarily a research tool because off-line image reconstruction from a series of component 2D images was required (reconstruction technique) and this was very time consuming. …
Canadian Journal of Cardiology | 2009
Amer M. Johri; Tara Baetz; Phillip A. Isotalo; Robert L. Nolan; Anthony J. Sanfilippo; Glorianne Ropchan
Primary cardiac lymphomas are rare extranodal lymphomas that should be distinguished from secondary cardiac involvement by disseminated non-Hodgkins lymphoma. Cardiac lymphomas often mimic other cardiac neoplasms, including myxomas and angiosarcomas, and often require multimodality cardiac imaging, in combination with endomyocardial biopsy, excisional biopsy or pericardial fluid cytology, to establish a definitive diagnosis. A 60-year-old immunocompetent man who presented with superior vena cava syndrome secondary to a right atrial, primary cardiac diffuse large B cell lymphoma (non-Hodgkins lymphoma) is described in the present article. The patient had no clinical evidence of disseminated lymphoma and was successfully treated with prompt surgical excision of his atrial mass, followed by anthracycline-based chemotherapy. The patient required multi-modality cardiac imaging to accurately identify and plan surgical excision of his cardiac lymphoma. The therapeutic management and clinical and radio-logical features of primary cardiac lymphoma are reviewed.