Magnetic resonance imaging of myocardial strain after acute ST-segment-elevation myocardial infarction: a systematic review

The purpose of this systematic review is to provide a clinically relevant, disease-based perspective on myocardial strain imaging in patients with acute myocardial infarction or stable ischemic heart disease. Cardiac magnetic resonance imaging uniquely integrates myocardial function with pathology. Therefore, this review focuses on strain imaging with cardiac magnetic resonance. We have specifically considered the relationships between left ventricular (LV) strain, infarct pathologies, and their associations with prognosis. A comprehensive literature review was conducted in accordance with the PRISMA guidelines. Publications were identified that (1) described the relationship between strain and infarct pathologies, (2) assessed the relationship between strain and subsequent LV outcomes, and (3) assessed the relationship between strain and health outcomes. In patients with acute myocardial infarction, circumferential strain predicts the recovery of LV systolic function in the longer term. The prognostic value of longitudinal strain is less certain. Strain differentiates between infarcted versus noninfarcted myocardium, even in patients with stable ischemic heart disease with preserved LV ejection fraction. Strain recovery is impaired in infarcted segments with intramyocardial hemorrhage or microvascular obstruction. There are practical limitations to measuring strain with cardiac magnetic resonance in the acute setting, and knowledge gaps, including the lack of data showing incremental value in clinical practice. Critically, studies of cardiac magnetic resonance strain imaging in patients with ischemic heart disease have been limited by sample size and design. Strain imaging has potential as a tool to assess for early or subclinical changes in LV function, and strain is now being included as a surrogate measure of outcome in therapeutic trials

Use of advanced echocardiography imaging techniques in the critically ill

Background: Critical care echocardiography has become standard of care in the ICU. New technologies have been developed and have shown potential clinical utility to elucidate myocardial dysfunction not seen with conventional imaging. We sought to determine the feasibility and potential clinical benefit of these techniques in common situations seen in the ICU. Hypothesis: Advanced echo techniques would be feasible in the majority of critically ill patients and have prognostic significance, clinical utility and diagnose cardiac abnormalities, potentially in a more sensitive manner than conventional techniques. Results: (a) Speckle tracking echocardiography (STE) Left ventricle and RV analysis with STE was feasibly in ~80% of patients. More dysfunction was found using STE vs conventional analysis. RV dysfunction assessed by STE held significant prognostic relevance in those with septic shock and highlighted subtle dysfunction induced by mechanical ventilation, both in animal and human studies. (b) 3D transthoracic echocardiography (3D TTE) Despite finding 3D TTE feasible in mechanically ventilated ICU patients (LV 72% and RV 55%), it lacked necessary low variability and high precision vs standard measures. (c) Myocardial contrast perfusion echocardiography (MCPE) Assessing acute coronary artery occlusion in the ICU patient is challenging. Troponin elevation, acute ECG changes, regional wall motion analysis on echo and overall clinical acumen often lack diagnostic capabilities. MCPE was found to be feasible in the critically ill and had better association predicting acute coronary artery occlusion vs clinical acumen alone. Conclusions: STE, 3D TTE and MCPE are feasible in the majority of ICU patients. STE may show dysfunction not recognised by conventional imaging. 3D TTE for volumetric analysis is likely not suitable for clinical use at this stage. MCPE may help guide interventions in acute coronary artery occlusion

Echocardiography

The book "Echocardiography - New Techniques" brings worldwide contributions from highly acclaimed clinical and imaging science investigators, and representatives from academic medical centers. Each chapter is designed and written to be accessible to those with a basic knowledge of echocardiography. Additionally, the chapters are meant to be stimulating and educational to the experts and investigators in the field of echocardiography. This book is aimed primarily at cardiology fellows on their basic echocardiography rotation, fellows in general internal medicine, radiology and emergency medicine, and experts in the arena of echocardiography. Over the last few decades, the rate of technological advancements has developed dramatically, resulting in new techniques and improved echocardiographic imaging. The authors of this book focused on presenting the most advanced techniques useful in today's research and in daily clinical practice. These advanced techniques are utilized in the detection of different cardiac pathologies in patients, in contributing to their clinical decision, as well as follow-up and outcome predictions. In addition to the advanced techniques covered, this book expounds upon several special pathologies with respect to the functions of echocardiography

Speckle-Tracking Imaging, Principles and Clinical Applications: A Review for Clinical Cardiologists

Evaluation of myocardial mechanics, although complex, has now entered the clinical arena, thanks to the introduction of bedside imaging techniques, such as speckle-tracking echocardiography

Left ventricular deformation: echocardiographic assessment and clinical implications in small animals

Echocardiography has become a very important diagnostic exam in veterinary cardiology, being consider as the exam of choice in many of the small animals cardiopathies. Recently, new echocardiographic techniques have been studied with the intent of improving diagnostic accuracy, introducing new parameters on the routine echocardiographic exam. These techniques, namely Tissue Doppler imaging and Specke Tracking, are already well established in human medicine cardiology and many studies have proven their value and effectiveness. During the last decade, these techniques have also been studied in veterinary medicine. Tissue Doppler imaging and Bi-dimensional Speckle Tracking deliver new parameters in evaluating the myocardium performance, as the evaluation of the deformation indices (Strain and Strain Rate), ventricular torsion and synchrony. In this review, relevance will be given to these parameters and how they affect changes on the left ventricle. This will be achieved by gathering studies recently made in various cardiopathies, as well as the normal values for myocardial deformation in healthy animals. This review will also focus on these techniques’ ability to detect early changes, allowing the clinicians to use proper and timely therapeutic decisions. This is a very important factor, since it could have impact on definitive diagnosis and future prognosis of several diseases.Em Medicina Veterinária, a ecocardiografia tornou-se um exame complementar de extrema importância no diagnóstico definitivo de várias cardiopatias, sendo considerada como o método diagnóstico de eleição. Recentemente, novas modalidades ecocardiográficas têm sido estudadas com o intuito de melhorar a capacidade de diagnóstico e introduzir novos parâmetros no exame ecocardiográfico de rotina. Em Medicina Humana, as referidas ténicas de ecocardiografia mais avançadas, como o Doppler tecidular e o Speckle Tracking são já utilizadas na rotina da prática clínica, existindo diversos estudos que comprovam o seu valor e eficácia. Durante a última década estas ténicas têm vindo também a ser estudadas em Medicina Veterinária, sendo o Speckle tracking bi-dimensional considerado o mais recente. Tanto o Doppler Tecidular como o Speckle Tracking fornecem novos parâmetros de avaliação da performance do miocárdio, como a avaliação dos parâmetros de deformação (Strain e Strain Rate), torsão ventricular e sincronia mecânica do miocárdio. Nesta revisão será dada relevância às alterações destes parâmetros no estudo do ventrículo esquerdo. Desta forma, esta revisão tem como objectivo reunir os estudos feitos recentemente em diversas cardiopatias, assim como em animais saudáveis, podendo estes servir como referência na validação futura dos parâmetros de deformação. Será dado maior relevo à capacidade destas técnicas detectarem alterações precocemente, possibilitanto ao clínico uma conduta terapêutica adequada, antes dos parâmetros obtidos na ecocardiografia convencional se apresentarem alterados. Este factor é de extrema importância para o desenvolvimento da abordagem terapêutica quer no prognóstico quer no diagnóstico definitivo das cardiopatias em Medicina Veterinária

Cardiovascular imaging 2010 in the International Journal of Cardiovascular Imaging

Cardiovascular Aspects of Radiolog

Cardiac and Mitochondrial Dysfunction during Diabetes Mellitus: Examination of Mitochondrial Import Mechanisms

Approximately 9% of the United States population is diagnosed with diabetes mellitus (DM), which is comprised of 2 distinct pathologies: type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). T1DM, which is caused by insufficient insulin production, affects approximately 5% of diabetic patients, while T2DM results from insulin resistance and affects 95% of all diabetic patients. Within diabetic patients, cardiac complications, such as diabetic cardiomyopathy, are the leading cause of morbidity and mortality. The mitochondrion has been implicated as an underlying factor in the etiology and progression of the cardiac contractile deficits and cardiac failure that accompany DM. The study of cardiac mitochondria is further complicated by the presence of two distinct mitochondrial subpopulations residing within the cardiomyocyte. The pool of mitochondria existing beneath the sarcolemmal membrane are termed the subsarcolemmal mitochondria (SSM), while the group that exists between the myofibrils is called the interfibrillar mitochondria (IFM). Assessment of mitochondrial subpopulations has revealed differential impact to both physiological and pathological stimuli. Specifically, during DM, the IFM are most impacted during T1DM, with the SSM being most impacted under T2DM pathological insult. During DM, proteomic analyses by our laboratory and others reveal decreased abundance of nuclear-encoded mitochondrial proteins essential for processes such as oxidative phosphorylation, fatty acid oxidation and tricarboxylic acid cycle in the subpopulation predominantly impacted by the DM type. Further, our laboratory has previously shown import efficiency to be down in the T1DM IFM, which could play a role in the proteomic dysregulation. Approximately 99% of the mitochondrial proteome is composed of nuclear-encoded proteins imported into the mitochondrion via a complicated mechanism of translocation that coordinates both the outer and inner mitochondrial membranes, thus highlighting the importance of studying the nuclear-encoded mitochondrial protein import process during pathological states. To date, evaluation of the diabetic heart using a highly sensitive echocardiographic analysis software in order to assess subtle changes in left ventricular function prior to overt contractile dysfunction during DM has not been completed. Additionally, the differential proteomic alterations in mitochondrial subpopulations resulting from distinct DM pathologies and the evaluation of inefficient nuclear-encoded mitochondrial protein import due to decrements in a key import constituent in the mitochondrial subpopulation predominantly affected, mitochondrial heat shock protein 70 (mtHsp70), have not been completed. Further, the mechanisms involved in miRNA import into the mitochondrion during DM remains limited. Therefore, the goal of the following studies was to examine subpopulation-specific mitochondrial proteome disruption stemming from inefficient nuclear-encoded mitochondrial protein import and/or increased miRNA influx into the mitochondrion, thus leading to increased contractile dysfunction during DM. T1DM was induced in 6-week-old mice with multiple low-dose (50mg/kg) streptozotocin (STZ) injections for 5 consecutive days. Hyperglycemia was confirmed and echocardiography performed at weeks 1, 3 and 6 post-diabetic onset. Conventional analyses revealed cardiac contractile deficits relative to control at 6-weeks post-T1DM onset. In contrast, short- and long-axis analyses using the speckle-tracking based strain analysis software demonstrated changes in the LV myocardium as early as 1-week post-diabetic onset. These findings show that analysis of myocardial function using speckle-tracking based strain analyses could provide a more precise method for evaluating cardiac contractile dysfunction during the progression of different pathological states. Our laboratory has previously shown that proteomic alterations specific to the T2DM SSM and T1DM IFM occur, potentially due to a decrement in nuclear-encoded mitochondrial protein import. Because mtHsp70, an essential component in the import of nuclear-encoded proteins into the mitochondrion is consistently down during DM, we generated a novel transgenic line with a cardiac-specific overexpression of mtHsp70. We subjected this line to STZ to generate a T1DM mouse model with mtHsp70 overexpression. Further, we utilized the db/db mouse model for T2DM and with a novel ovarian transplantation procedure, we were able to generate an increased abundance of mtHsp70 db/db and control animals, which were approximately 20-weeks-old before hearts were excised and mitochondrial subpopulations isolated. When assessing nuclear-encoded mitochondrial protein import efficiency in the mitochondrial subpopulations during both types of DM, we found decrements to this process in the SSM of T2DM mice and IFM of T1DM mice, which was subsequently restored with mtHsp70 overexpression. Further, alterations to the most impacted mitochondrial subpopulations proteome were noted, with mtHsp70 affording protection. Additionally, we also found mtHsp70 protein content to be down in the T1DM and T2DM human heart. (Abstract shortened by ProQuest.)