Kinematic analysis of left ventricular deformation in myocardial infarction using magnetic resonance cardiac tagging

The Magnetic Resonance (MR) tagging technique provides detailed information about 2D motion in the plane of observation. Interpretation of this information as a reflection of the 3D motion of the entire cardiac wall is a major problem. In finite element models of the mechanics of the infarcted heart, an infarcted region causes motional asymmetry, extending far beyond the infarct boundary. Here we present a method to quantify such asymmetry inamplitude and orientation. For this purpose images of a short-axis cross-section of the ejecting left ventricle were acquired from 9 healthy volunteers and 5 patients with myocardial infarction. MR-tags were applied in a 5 mm grid at end-diastole. The tags were tracked by video-image analysis. Tag motion was fitted to a kinematic model of cardiac motion. For the volunteers and the patients the center of the cavity displaced by about the same amount(p=0.11) during the ejection phase: 3.8 ± 1.4 and 3.0 ± 0.9 mm (mean ± sd), respectively. Cross-sectional rotation and the decrease in cross-sectional area of the cavity were both greater in the volunteers than in the patients: 6.4 ± 1.5 vs. 3.0 ± 0.8 degrees (p<0.001), and 945 ± 71 vs. 700 ± 176 mm 2 (p=0.02), respectively. In the patients, asymmetry of wall motion, as expressed by a sine wave dependency of contraction around the circumference, was significantly enlarged (p=0.02). The proposed method of kinematic analysis can be used to assess cardiac deformation in humans. We expect that by analyzing images of more cross-sections simultaneously, the 3D location and the degree of infarction can be assessed efficiently.     

Sustained postinfarction myocardial oedema in humans visualised by magnetic resonance imaging

OBJECTIVE—To demonstrate postinfarction myocardial oedema in humans with particular reference to the longitudinal course, using magnetic resonance imaging (MRI).
DESIGN—Prospective observational study. Subjects were studied one week, one month, three months, six months, and one year after presenting with a myocardial infarct.
SETTING—Cardiology and magnetic resonance departments in a Danish university hospital.
PATIENTS—10 patients (three women, seven men), mean (SEM) age 58.2 (3.20) years, with a first transmural myocardial infarct.
MAIN OUTCOME MEASURES—Location and duration of postinfarction myocardial oedema.
RESULTS—All patients had signs of postinfarction myocardial oedema. The magnetic resonance images were evaluated by two blinded procedures, employing two MRI and two ECG observers: (1) MRI determined oedema location was compared with the ECG determined site of infarction and almost complete agreement was found; (2) the time course of postinfarction myocardial oedema was explored semiquantitatively, using an image ranking procedure. Myocardial oedema was greatest at the initial examination one week after the infarction, with a gradual decline during the following months (Spearman's rank correlation analysis: ρ_{observer 1} = 0.94 (p < 0.0001) and ρ_{observer 2} = 0.97 (p < 0.0001)). The median duration of oedema was six months.
CONCLUSIONS—Postinfarction myocardial oedema seems surprisingly long lasting. This observation is of potential clinical interest because the oedema may have prognostic significance.


Keywords: myocardial infarction; myocardial oedema; magnetic resonance imaging     

Missed diagnosis of unruptured,huge left ventricular pseudoaneurysm

We report a case of a huge left ventricular pseudoaneurysm following myocardial infarction. Early after myocardial infarction, the pseudoaneurysm was missed during the cardiac examination. The patient underwent coronary bypass surgery with endoaneurysmorraphy of the pseudoaneurysm, and made a satisfactory recovery.     

Differential diagnosis of left ventricular hypertrophy: usefulness of multimodality imaging and tissue characterization with cardiac magnetic resonance

Differential diagnosis of asymmetrical left ventricular hypertrophy may be challenging, particularly in patients with history of hypertension. A middle‐aged man underwent an echocardiographic examination during workup for hypertension, which unexpectedly showed significant asymmetrical septal hypertrophy and raised suspicion for hypertrophic cardiomyopathy. Cardiovascular magnetic resonance confirmed the asymmetrical hypertrophy. No myocardial late gadolinium contrast enhancement was seen. However, precontrast T1 mapping revealed a low native myocardial T1 value. This was highly suggestive of Anderson‐Fabry disease, which was subsequently proved with very low alpha galactosidase enzyme levels and mutation analysis. The case illustrates clinical usefulness of multimodality imaging and the novel tissue characterization techniques for assessment of left ventricular hypertrophy.     

Diagnosis of double-chambered left ventricle by echocardiogram and cardiac magnetic resonance imaging: A rare case in an adult

Double-chambered left ventricle (DCLV) is a very rare malformation which is congenital. In most cases, the left ventricle (LV) is divided into two parallel chambers by a septum or aberrant muscular structure, with fewer superior–inferior arrangement. Here, we present the case of an asymptomatic 25-year-old man who was diagnosed with superior–inferior arrangement DCLV on transthoracic echocardiography and cardiac magnetic resonance (CMR). DCLV generally does not cause serious outcomes. Owing to absence of any symptoms, no treatment was provided, and the patient was regularly followed up.     

An unusual presentation of a large left ventricular pseudoaneurysm

Left ventricle pseudoaneurysm is an infrequent complication of myocardial infarction, and is most commonly localized in the inferoposterior left ventricular segments. We describe a patient post anterior myocardial infarction, who presented with pulmonary edema and a large pseudoaneurysm of the anterolateral wall with involvement of the anterolateral papillary muscle, resulting in severe mitral regurgitation. The patient underwent successful operation and is currently well.     

Long-term survival following cardiac rupture with subsequent development of left ventricular pseudoaneurysm

This report describes a patient who survived rupture of the left ventricular free wall following a myocardial infarction and who then subsequently went on to develop a pseudoaneurysm. The rupture became clinically recognized when the patient developed cardiac tamponade. A large hemopericardium was evacuated by performing a thoracotomy and a pericardiotomy. Although not evident at the time of the initial catheterization, a pseudoaneurysm developed over the ensuing months. The aneurysm was initially recognized by radionuclide angiography and confirmed by left ventricular angiography at a second cardiac catheterization. The aneurysm was successfully resected, and the patient was alive and functioning normally 18 months after rupture and 12 months after aneurysmectomy.     

磁共振延迟增强显像诊断心肌梗死的临床研究

目的 了解磁共振延迟增强(MR-DE)显像在心肌梗死诊断中的临床意义。方法 42例拟诊冠心病的患者,按临床分为心肌梗死、心肌缺血、正常3组,行MR-DE显像,其中25例行冠状动脉造影(CAG),并按冠脉狭窄程度分为狭窄<50％,50％～99％和100％3组。计算MR-DE检出心肌梗死的敏感性与特异性,并分别分析临床分组和CAG分组的MR-DE结果。结果 利用延迟增强判断心肌梗死,敏感性、特异性和诊断准确性分别为87.5％,94.1％和92.8％。出现延迟增强的比例,在临床分组中,分别为87.5％,8.7％和0％;在CAG分组中,分別为0％,50％和100％。结论 MR-DE显像对心肌梗死诊断有较高临床意义。     

Principles, current status and clinical implications of ischaemic heart disease assessment by cardiac magnetic resonance imaging

Cardiac magnetic resonance imaging (CMR) has matured into a robust, accurate and highly reproducible imaging modality for the assessment of cardiac function and ischaemic heart disease. The unique physical properties of CMR permit depiction of pathology-specific tissue contrast based on differences in tissue composition, such as myocardial oedema, necrosis and fibrosis. This can be imaged at high spatial resolution allowing characterisation of the acuity of an ischaemic event, the presence and extent of myocardial ischaemia, necrosis and viability. Prognostically important information obtained from CMR evaluation of ischaemic heart disease, such as left ventricular ejection fraction, infarct size and transmurality, infarct location and the presence of intraventricular mechanical dyssynchrony may be used to guide coronary revascularisation, device and medical therapies.     

The relationship between serial postinfarction T wave changes and infarct size and ventricular function as determined by cardiac magnetic resonance imaging

Background

The value of sequential T wave changes on the electrocardiogram (ECG) has less well been described than ST-segment changes in the follow-up of patients with myocardial infarction (MI). We investigated whether the amplitude of T wave positivity correlates with infarct size (IS) and left ventricular ejection fraction (LVEF) measured using cardiac magnetic resonance imaging 3 months after reperfusion therapy.

Materials and Methods

Fifty-five patients with a first acute MI referred for primary percutaneous coronary intervention were included. Electrocardiograms were analyzed within 4 hours after reperfusion and at 3 months, measuring T wave ampitudes in 2 contiguous infarct-related leads, summed up as one value called T wave amplitude. Cardiac magnetic resonance imaging was performed at 3 months of follow-up. Correlations between T wave amplitude, IS, and LVEF were tested with Pearson r correlation coefficient test. Subanalyses were performed using a 2-sample t test.

Results

A good correlation was found between LVEF and IS (r = −0.7, P < .0001). Most of the patients had inferior MI location (69%). In this group, there were significant positive correlations between the amount of T wave positivity and both IS (r = −0.40, P = .012) and LVEF (r = 0.33, P = .043). Results were similar in patients with and without an increase in T wave amplitude during follow-up.

Conclusions

In this study of patients with reperfused MI, patients with inferior locations demonstrated a statistically significant relationship between the amount of positivity of T wave amplitude and both IS and LVEF measured at 3 months. Furthermore, these results were independent of whether the T wave positivity was persistent or evolutionary between the immediate postreperfusion and 3-month ECG recordings.     

A novel technique using biplane cine magnetic resonance imaging to evaluate left ventricular volume in children

The purpose of the study is to determine the feasibility of a novel simplified technique using cine magnetic resonance imaging (MRI) to assess left ventricular (LV) volume and ejection fraction (EF) validated by comparison with biplane LV angiography. Previous MRI studies to assess LV volumes have used multiple axial planes, which are compromised by partial volume effects and are time consuming to acquire and analyze. Accordingly, we developed a simplified imaging approach using biplane cine MRI and imaging planes aligned with the intrinsic cardiac axes of the LV. We studied 20 children (aged 4 months to 10 years) with various heart diseases. The accuracy of cine MRI was compared with that of LV angiography in all patients. LV volumes were calculated using Simpson's rule algorithm, for both MRI and LV angiography. LV volumes determined from MRI were slightly underestimated but correlated reasonably well with angiographic volumes (LVEDV: Y = 0.88X + 1.58, r = 0.99, LVESV: Y = 0.73X + 1.03, r = 0.98). Most importantly, even in patients who had abnormal ventricular curvature such as in tetralogy of Fallot, MRI determined LV volumes correlated well with angiographic values. The MR study was completed within 35 min in all patients. In conclusion, simplified biplane cine MRI, using the intrinsic LV axis planes, permits noninvasive assessment of LV volumes in views comparable to standard angiographic projections and appears practical for clinical use in childhood heart disease since the scan and analysis times are relatively short.     

Changes of the left ventricle after myocardial infarction—estimation with cine magnetic resonance imaging during the first six months

Background: In recent years, the interest of cardiologists has focused increasingly on the morphologic and functional changes of the left ventricle after myocardial infarction (MI), due to their great prognostic significance for the patient. Hypothesis: The aim of this study was to evaluate changes in left ventricular morphology and function during the first 6 months following MI. Methods: In all, 61 patients (17 women, 44 men, age 36–83 years) were examined with cine magnetic resonance imaging (CMRI) 1,4, and 26 weeks after myocardial infarction. Thirty-two patients had anterior MI and 29 patients had posterior MI. According to enzyme-derived infarct weight, 15 patients had small infarcts (<20 g), 19 had intermediate-sized infarcts (20–40 g), and 27 patients had large infarcts (>40 g). CMRI was performed in the true short axis of the left ventricle. In each examination, left ventricular end-diastolic and end-systolic volume indices (LVEDVI, LVESVI), stroke volume index (LVSVI), ejection fraction (LVEF), and regional thickness, mass, and motility of the myocardial wall—diastolic thickness (IDdia), infarct mass (IM) and motility (MOT) of the infarct area and diastolic and systolic thickness (VDdia, VDsys), muscular mass (VM), and motility (VMOT)—were determined. In addition, patients were divided into subgroups according to New York Heart Association (NYHA) functional status at baseline. Results: In the total group, LVEDVI increased from 73·9 ± 23·5 ml/m² to 85·4 ± 28·1 ml/m² (p <0·001) and LVESVI from 40·5 ± 19·4 ml/m² to 51·2 ± 29·0 ml/m² (p <0·001). In the subgroups the development depended on infarct size and location. LVSVI and LVEF remained more or less constant except for large anterior infarctions. All changes of the myocardial wall depended on infarct size and location: In all patients IDdia decreased from 10·4 ± 1·6 mm to 8·9 ± 1·7 mm (p <0·001), IMOT from 2·0± 1·6 mm to 0·5 ±2·9 mm (p<0·001). IM increased from 41 ± 21 g to 45 ± 25 g (p <0·001). In the total group, VDdia increased from 11·9 ± 1·6 mm to 12·4 ± 1·8 mm (p <0·05), VDsys from 16·6 ± 2·5 mm to 17·2 ± 3·1 mm (p <0·05). In the subgroups changes varied: VDdia and VDsys decreased markedly in large anterior wall infarctions. VM increased in the total cohort from a mean of 246 ± 66 g to 276 ± 80 g (p <0·001). VMOT decreased from 7·1 ±2·4 mm to 6·3 ± 2·7 mm (p <0·05). Loss of motility was most pronounced in anterior infarctions. The volume–mass ratio, a measure of the success of compensation of volume increase by myocardial hypertrophy, decreased in small infarcts, remained unchanged in intermediate infarcts, and increased in large infarcts. There was a trend toward improvement of the NYHA functional status during the observation period. Conclusions: Changes of the left ventricular chamber during the first 6 months following MI are dependent on its size and location, with large anterior infarctions having the worst course. Myocardial wall remodeling is also dependent on infarct size and location, and the volume–mass ratio increases in the presence of large areas of necrosis, indicating the noncompensatory effect of myocardial hypertrophy. However, these changes have no clinical effect during the first half year after MI.     

Giant left ventricular pseudoaneurysm presenting with hemoptysis

Left ventricular (LV) pseudoaneurysm is a late mechanical complication of myocardial infarction (MI). A giant LV pseudoaneurysm is a rare presentation. We report a case of a giant LV pseudoaneurysm in a post MI patient, who presented with hemoptysis. Hemoptysis is a rare clinical presentation of LV pseudoaneurysm. The patient had successful surgical repair of the aneurysm and had a favorable outcome in 9 mo’ follow-up. The imaging modalities and surgical treatment of a pseudoaneurysm is discussed.     

静息心肌灌注显像与超声心动图、磁共振测定左室大小的相关性研究

目的 评价静息心肌灌注显像（Rest MPI）、心肌磁共振显像（MRI）和超声心动图（Echo）测定左室大小的相关性,分析Rest MPI中左室大小与缺血程度、缺血面积是否相关。方法：分析121例于住院1周内行Rest MPI、MRI、Echo三项检查的患者,分别测定左室大小。将MRI、Echo分别与Rest MPI检测结果比较, 行直线相关分析及Bland-Altman一致性检验。结果 Rest MPI横径、长径均较MRI、Echo所测左室大小偏低。Rest MPI横径与MRI、Echo所测左室大小呈正相关（r=0.873,P<0.01;r=0.867,P<0.01）;Rest MPI长径与MRI、Echo所测左室大小呈正相关（r=0.868,P<0.01;r=0.850,P<0.01）。经Bland-Altman一致性检验, Rest MPI与MRI、Echo所测左室大小均有等价性。Pearson相关分析结果显示,缺血程度、缺血面积与左室横径均呈正相关（r=0.631,P＜0.01;r=0.642,P＜0.01）,与左室长径均呈正相关（r= 0.632,P＜0.01;r=0.641,P＜0.01）。结论 Rest MPI 与MRI、Echo对评估左室大小具有等价性。静息心肌灌注显像中的缺血程度、缺血面积与左室大小相关。