Analysis of Echocardiography Images Using Grid Independent Technique for Patients with Mitral Valve Problems (MVP)

With echocardiography images collected by a transthoracic transducer, can be used to evaluate the mitral valve problems. Incorrect surgical of mitral valves failure will cause death and the surgical repair can be improved by knowing the correlations between backflow and the rigidity of mitral valve. In this study, a nearly method for identifying the mitral valve rigidity from two-dimensional (2D) images of echocardiography is presented. This method employs the grid independent technique. Systolic and diastolic stages of mitral valve condition were investigated by 10 patients with MVP. The results show linear correlation between degeneration of the valves and volume of backflow. The findings are the prediction of the behavior of the mitral valves and blood flow which can assist the medical practitioners in their decision on the patients’ treatments

Semi-automatic algorithm for construction of the left ventricular area variation curve over a complete cardiac cycle

<p>Abstract</p> <p>Background</p> <p>Two-dimensional echocardiography (2D-echo) allows the evaluation of cardiac structures and their movements. A wide range of clinical diagnoses are based on the performance of the left ventricle. The evaluation of myocardial function is typically performed by manual segmentation of the ventricular cavity in a series of dynamic images. This process is laborious and operator dependent. The automatic segmentation of the left ventricle in 4-chamber long-axis images during diastole is troublesome, because of the opening of the mitral valve.</p> <p>Methods</p> <p>This work presents a method for segmentation of the left ventricle in dynamic 2D-echo 4-chamber long-axis images over the complete cardiac cycle. The proposed algorithm is based on classic image processing techniques, including time-averaging and wavelet-based denoising, edge enhancement filtering, morphological operations, homotopy modification, and watershed segmentation. The proposed method is semi-automatic, requiring a single user intervention for identification of the position of the mitral valve in the first temporal frame of the video sequence. Image segmentation is performed on a set of dynamic 2D-echo images collected from an examination covering two consecutive cardiac cycles.</p> <p>Results</p> <p>The proposed method is demonstrated and evaluated on twelve healthy volunteers. The results are quantitatively evaluated using four different metrics, in a comparison with contours manually segmented by a specialist, and with four alternative methods from the literature. The method's intra- and inter-operator variabilities are also evaluated.</p> <p>Conclusions</p> <p>The proposed method allows the automatic construction of the area variation curve of the left ventricle corresponding to a complete cardiac cycle. This may potentially be used for the identification of several clinical parameters, including the area variation fraction. This parameter could potentially be used for evaluating the global systolic function of the left ventricle.</p

Track 5: Cardiology and the imaging revolution - Part I

Cardiology and the imaging revolution

Acute myocardial infarction : early diagnosis and the prognostic value of ECG and echocardiography

Introduction Acute myocardial infarction (AMI) is a main cause of death. Despite vast improvements in management and treatment strategies over the past decades, morbidity and mortality after an AMI remains high. For patients with AMI and ST-segment elevations (STEMI), urgent management has been shown to be associated with reductions in both morbidity and mortality. Various pre-hospital management strategies have been implemented, during which STEMI patients can be referred directly to the catheterization laboratory instead of first being assessed in the emergency department. Valuable minutes can thus be saved. However, it is important that the diagnosis is correct which can be more challenging in a setting where the referring cardiologist is not at the same location as the patient and the clinical setting therefore needs to be reported by the paramedic staff. Studies on the accuracy of pre-hospital STEMI diagnoses are limited. In order to expedite management for STEMI patients, international guidelines have included benchmark time targets. Little is known regarding gender differences in the achievement of these time targets, and the feasibility of obtaining a pre-hospital ECG within ten minutes of ambulance arrival has been questioned. For patients who survive an AMI, there is a risk of transient or permanent damage to the left ventricle. Such damage can be quantified by echocardiography. It is shown that patients with a reduced left ventricular ejection fraction (LVEF) have a higher risk of sudden cardiac death than patients with normal LVEF. For patients with reduced LVEF despite optimal medical treatment, an implantable cardioverter defibrillator (ICD) can reduce mortality. This benefit is not seen until after several months have passed since the AMI. This is further complicated by the fact that the risk of death is highest in the early days, weeks and months after an AMI. Therefore, finding predictors in the early phase after an AMI, preferably while the patient is still admitted to the ward, would likely be beneficial in the selection of patients for ICD treatment. Aims The overall aim of this thesis was to find easily obtainable measurements by ECG and echocardiography that could improve the prognosis for patients with acute myocardial infarction. More specifically, the aim was to study the rate of false-positive STEMI diagnoses based on pre-hospital ECGs (study I), study gender differences in time intervals and adherence to guideline set time targets (study II), study the predictive value of low-dose dobutamine stress echocardiography on the improvement of LVEF (study III) and investigate the use of discharge ECG in the early prediction of ICD candidates (study IV). Methods In study I all patients for whom a pre-hospital ECG had been transmitted to the investigating hospital during 2013 were included. In study II, patients with a STEMI diagnosis and a prehospital ECG between December 2010 and July 2015 were included. Information on whether a pre-hospital STEMI diagnosis had been set or not was collected from medical charts and the final diagnosis of STEMI was found in the national quality registry SWEDEHEART. For both study I and study II, information on time intervals were collected from ambulance charts, medical charts, a database collecting information on pre-hospital ECGs, and SWEDEHEART. In studies III and IV, adult patients with an at least moderately reduced left ventricular function (defined as LVEF ≤ 40%) with a life expectancy of more than one year and who were admitted for AMI were invited and followed by clinical visits and echocardiographic examinations. In study III, a low-dose dobutamine stress echocardiogram was performed within one week of the AMI and in study IV, the discharge ECG was reviewed. Results In study I, 16% (95% CI 10 – 23) out of 115 patients with a suspected STEMI based on prehospital ECGs were discharged with alternative diagnoses. Measured as the time from ambulance arrival at the patient’s location, the time target of reperfusion therapy within 90 minutes was achieved for almost all patients (98%), but the achievement of a pre-hospital ECG within ten minutes was only met for 16% of the cohort. The delay time to pre-hospital ECG was significantly longer for women than for men, 20 vs. 13 minutes (p < 0.001). In study II, 539 patients with STEMI and a pre-hospital ECG were included. A pre-hospital ECG was obtained within ten minutes for 22% of the cohort, and the target was more likely to be achieved for men than for women (29% vs. 14%, p = 0.001). Among all patients, 88% reached the target of reperfusion therapy within 90 minutes and there was no difference between men and women. Women had a significantly longer delay time between symptom onset and emergency call than men (median 61 vs. 45 minutes, p = 0.031). In study III, among 96 patients with an at least moderately reduced LVEF after an AMI, 60% had an LVEF ≥ 35% after three months. Patients with an LVEF ≤ 35% after three months had a significantly lower left ventricular function at both resting and stress echocardiography, measured as LVEF, mitral annular plane systolic excursion (MAPSE) and peak systolic velocity (PSV). Baseline LVEF was a good predictor of recovery with a C-statistic of 85% (95% CI 74 – 94). None of the other variables, including the stress echocardiography variables, were better discriminators. In study IV, 87 patients with LVEF ≤ 40% after an AMI were included. Patients who had a pathologic R-wave progression on the discharge ECG were four times more likely to receive an ICD than those with normal R-wave progression (HR 4.0, 95% CI 1.1-14.3, p = 0.033). None of the patients without a pathologic R-wave progression, pathologic Q-waves, or intraventricular conduction abnormalities, received an ICD or suffered from malignant arrhythmias during the follow-up period. Conclusions The rate of false-positive catheterization laboratory activations based on pre-hospital STEMI diagnoses is well in comparison to rates reported based on in-hospital triage. Still, there are gender differences favoring men in regards of delay time from symptom onset to emergency call and ambulance arrival to pre-hospital ECG. The target of obtaining a pre-hospital ECG within ten minutes is met for only around one fifth of the patients, and improvements regarding this are warranted. For patients with heart failure after an AMI, baseline LVEF is a strong predictor of improved recovery while simple measurements of LVEF, MAPSE and PSV during low-dose dobutamine stress echocardiography did not add prognostic information. Patients with a pathologic R-wave progression have a significantly higher risk of receiving an ICD, and patients without pathologic R-wave progression, or Q-waves, or intraventricular conduction abnormalities are unlikely to receive an ICD and could be seen as a low-risk population

Infective endocarditis

The term ‘predisposing heart condition’ is used as an indication of antimicrobial prophylaxis to prevent infective endocarditis (IE) and as a criterion for diagnosing IE according to the modified Duke criteria. Whereas the use of the term for antimicrobial prophylaxis is well defined, the criterion for diagnosing IE is not. The general objective of this thesis is to narrow the definition of a predisposing heart condition in ‘native’ valves for the diagnosis of IE. Therefore, we reviewed the literature and the evidence about specific heart conditions reported to be a risk factor for IE. In parallel, we reviewed the imaging technique available at the time these studies were published and compared the results with imaging from today’s perspectives and current definitions of a specific heart condition (i.e. valvular disease). Finally, we evaluated the knowledge and opinion of clinicians about the term predisposing heart condition. Our literature review included 207 studies, the vast majority of which were descriptive. Only a few studies investigated valve pathology as a risk factor for IE via analytical statistics. In addition, three-quarters of all included studies involved patients who presented with IE prior to the publication of the modified Duke criteria. Studies focussing on mitral valve prolapse (MVP, 116 publications), prior IE (96 publications), and bicuspid aortic valve (BAV, 78 publications) provided the most data. The odds ratio of developing IE for a patient who had previously experienced an episode of it was approximately 2.5. The mean proportion of patients with IE plus a history of previous IE was 8.3% (median 7.1%, interquartile range [IQR] 4.9%–10.2%). One study associated BAV with a higher risk of IE (hazard ratio 6.3). In 77 descriptive studies, a median of approximately 6% of patients with IE had BAV as an underlying condition. Our literature review on the evolution of imaging methods indicated, however, a considerable influence of medical progress on the diagnosis of MVP. Six analytical studies and 90 of the 110 descriptive studies included patients prior to the publication of the modified Duke criteria in 2000. For many years, MVP was diagnosed via auscultation only, and echocardiographic means for diagnosis were used in the late 90s. Therefore, both the risk of developing IE and the proportion of patients with IE and MVP as a predisposing factor could not be quantified. The literature review on mitral valve stenosis (MS, 23 publications) and pathologies involving the pulmonary valve (18 publications) and the tricuspid valve (nine publications) provided little data. These publications had inconsistent results and low proportions of patients with IE had these valve pathologies. The significance of aortic valve stenosis (AS, 46 publications), mitral valve insufficiency (MI, 41 publications), and aortic valve insufficiency (AI, 39 publications) as a predisposing heart condition was difficult to assess from today’s perspective because of the progress made in imaging methods; of these studies, 75.6%, 78.6%, and 79.5%, respectively, included patients prior to the publication of the modified Duke criteria in the year 2000. In addition, except for AS (1989), the categorisation of mild, moderate, and severe valve pathology was established in 1998 or 2006. The publications had considerable heterogeneity with a wide distribution of results. An observational study indicated that with an increased incidence of AS, the risk of developing IE rises. Only one of these 126 publications for these three valve pathologies used analytical statistics. Congenital AS was associated with a higher risk of IE (hazard ratio of 4.9). The results from the literature review parallel those from a survey that we performed to evaluate the knowledge and opinion of clinicians on the term predisposing heart condition. The survey indicated that there is significant uncertainty among clinicians regarding what is considered to be a Duke minor criterion for a predisposing heart condition in a native valve. The results from 318 questionnaires with responses from specialists in the fields of internal medicine, infectious diseases, and cardiology provided a wide range of answers. Their answers also showed that what the participants believed to be a current Duke minor criterion and what they thought should be a minor criterion had a median accordance of 33%. Taken together, these findings demonstrate that there is uncertainty about what is considered a predisposing heart condition for the diagnosis of IE. This uncertainty is demonstrated in our extensive literature review and reflected in our survey among clinicians. The vast majority of studies used only descriptive statistics and included patients prior to the publication of the modified Duke criteria (2000). The tremendous progress in imaging methods and categorisation of valve pathologies since then makes it difficult to interpret the literature review analyses from today’s perspective. Nonetheless, studies on MVP, a prior episode of IE, and BAV had the highest representation in the literature. Among these three pathologies, MVP is most likely to be affected by the evolution of imaging methods, and therefore its risk cannot be quantified. Sensitivity analyses and mathematical models performed on the data obtained in this systematic review may help to further narrow the definition of a predisposing heart condition

Finding the Mitral Annular Lines From 2-D + 1-D Precordial Echocardiogram Using Graph-Search Technique

The apical four-chamber view echocardiogram collected by a transthoracic transducer can be used to evaluate the left ventricle volume. In the diastole, the left ventricle and left atrium become one chamber. In this case, the left ventricle and left atrium need to be separated using a “mitral annular line” so the volume of the left ventricle can be estimated. In this paper, a nearly automatic method for identifying the mitral annular lines from two-dimensional (2-D) + one-dimensional (1-D) precordial four-chamber view echocardiogram is presented. This method employs the optical flow technique and graph-search approach. The mitral annular line sequence is found by finding the shortest path in a weighted directed graph. The vertices in the graph are candidates for the mitral annular lines. The weights on the directed edges are determined using the optical flow technique. The proposed method requires only a physician to provide a point that is always in the left ventricular chamber. Experimental results show that the average error for the left ventricle volume obtained based on the computed mitral annular lines is 3%

Infective endocarditis: What are predisposing conditions in native valves?

The term ‘predisposing heart condition’ is used as an indication of antimicrobial prophylaxis to prevent infective endocarditis (IE) and as a criterion for diagnosing IE according to the modified Duke criteria. Whereas the use of the term for antimicrobial prophylaxis is well defined, the criterion for diagnosing IE is not. The general objective of this thesis is to narrow the definition of a predisposing heart condition in ‘native’ valves for the diagnosis of IE. Therefore, we reviewed the literature and the evidence about specific heart conditions reported to be a risk factor for IE. In parallel, we reviewed the imaging technique available at the time these studies were published and compared the results with imaging from today’s perspectives and current definitions of a specific heart condition (i.e. valvular disease). Finally, we evaluated the knowledge and opinion of clinicians about the term predisposing heart condition. Our literature review included 207 studies, the vast majority of which were descriptive. Only a few studies investigated valve pathology as a risk factor for IE via analytical statistics. In addition, three-quarters of all included studies involved patients who presented with IE prior to the publication of the modified Duke criteria. Studies focussing on mitral valve prolapse (MVP, 116 publications), prior IE (96 publications), and bicuspid aortic valve (BAV, 78 publications) provided the most data. The odds ratio of developing IE for a patient who had previously experienced an episode of it was approximately 2.5. The mean proportion of patients with IE plus a history of previous IE was 8.3% (median 7.1%, interquartile range [IQR] 4.9%–10.2%). One study associated BAV with a higher risk of IE (hazard ratio 6.3). In 77 descriptive studies, a median of approximately 6% of patients with IE had BAV as an underlying condition. Our literature review on the evolution of imaging methods indicated, however, a considerable influence of medical progress on the diagnosis of MVP. Six analytical studies and 90 of the 110 descriptive studies included patients prior to the publication of the modified Duke criteria in 2000. For many years, MVP was diagnosed via auscultation only, and echocardiographic means for diagnosis were used in the late 90s. Therefore, both the risk of developing IE and the proportion of patients with IE and MVP as a predisposing factor could not be quantified. The literature review on mitral valve stenosis (MS, 23 publications) and pathologies involving the pulmonary valve (18 publications) and the tricuspid valve (nine publications) provided little data. These publications had inconsistent results and low proportions of patients with IE had these valve pathologies. The significance of aortic valve stenosis (AS, 46 publications), mitral valve insufficiency (MI, 41 publications), and aortic valve insufficiency (AI, 39 publications) as a predisposing heart condition was difficult to assess from today’s perspective because of the progress made in imaging methods; of these studies, 75.6%, 78.6%, and 79.5%, respectively, included patients prior to the publication of the modified Duke criteria in the year 2000. In addition, except for AS (1989), the categorisation of mild, moderate, and severe valve pathology was established in 1998 or 2006. The publications had considerable heterogeneity with a wide distribution of results. An observational study indicated that with an increased incidence of AS, the risk of developing IE rises. Only one of these 126 publications for these three valve pathologies used analytical statistics. Congenital AS was associated with a higher risk of IE (hazard ratio of 4.9). The results from the literature review parallel those from a survey that we performed to evaluate the knowledge and opinion of clinicians on the term predisposing heart condition. The survey indicated that there is significant uncertainty among clinicians regarding what is considered to be a Duke minor criterion for a predisposing heart condition in a native valve. The results from 318 questionnaires with responses from specialists in the fields of internal medicine, infectious diseases, and cardiology provided a wide range of answers. Their answers also showed that what the participants believed to be a current Duke minor criterion and what they thought should be a minor criterion had a median accordance of 33%. Taken together, these findings demonstrate that there is uncertainty about what is considered a predisposing heart condition for the diagnosis of IE. This uncertainty is demonstrated in our extensive literature review and reflected in our survey among clinicians. The vast majority of studies used only descriptive statistics and included patients prior to the publication of the modified Duke criteria (2000). The tremendous progress in imaging methods and categorisation of valve pathologies since then makes it difficult to interpret the literature review analyses from today’s perspective. Nonetheless, studies on MVP, a prior episode of IE, and BAV had the highest representation in the literature. Among these three pathologies, MVP is most likely to be affected by the evolution of imaging methods, and therefore its risk cannot be quantified. Sensitivity analyses and mathematical models performed on the data obtained in this systematic review may help to further narrow the definition of a predisposing heart condition

Finding the Mitral Annular Lines from 2-Dd Precordial Echocardiogram Using Graph-Search Technique

The apical four-chamber view echocardiogram collected by a transthoracic transducer can be used to evaluate the left ventricle volume. In the diastole, the left ventricle and left atrium become one chamber. In this case, the left ventricle and left atrium need to be separated using a &quot; mitral annular line&quot; so the volume of the left ventricle can be estimated. In this paper, a nearly automatic method for identifying the mitral annular lines from two-dimensional (2 -D) one-dimensional (1-D) precordial four-chamber view echocardiogram is presented. This method employs the optical flow technique and graph-search approach. The mitral annular line sequence is found by finding the shortest path in a weighted directed graph. The vertices in the graph are candidates for the mitral annular lines. The weights on the directed edges are determined using the optical flow technique. The proposed method requires only a physician to provide, a point that is always in the left ventricular chamber. Experimental results show that the average error for the left ventricle volume obtained based on the computed mitral annular lines is 3%

Automated analysis of 3D echocardiography

In this thesis we aim at automating the analysis of 3D echocardiography, mainly targeting the functional analysis of the left ventricle. Manual analysis of these data is cumbersome, time-consuming and is associated with inter-observer and inter-institutional variability. Methods for reconstruction of 3D echocardiographic images from fast rotating ultrasound transducers is presented and methods for analysis of 3D echocardiography in general, using tracking, detection and model-based segmentation techniques to ultimately fully automatically segment the left ventricle for functional analysis. We show that reliable quantification of left ventricular volume and mitral valve displacement can be achieved using the presented techniques.SenterNovem (IOP Beeldverwerking, grant IBVC02003), Dutch Technology Foundation STW (grant 06666)UBL - phd migration 201