Ultrasonic Tissue Characterization: Review of a Noninvasive Technique for Assessing Myocardial Viability

The determination of myocardial perfusion and myocardial viability has prognostic and therapeutic implications, particularly in the current era of percutaneous transluminal coronary angioplasty and thrombolytic therapy. Several modes of investigation, including positron emission tomography, thallium-201 scintigraphy, and nuclear magnetic resonance imaging are used to differentiate viable from nonviable myocardium. Though these noninvasive tests are useful diagnostic modalities, they are expensive, time consuming, and too cumbersome to be used in the acute setting. Expeditious distinction between viable and nonviable myocardium, during acute coronary syndromes, is of great importance since reperfusion can minimize the extent ofischemic injury and infarction. An expanding body of evidence confirms that ultrasonic tissue characterization has great potential to become a practical bedside diagnostic tool in the search for salvageable myocardium. Further clinical investigative studies would help accomplish a better understanding of the complex interaction between ultrasound and myocardium.     

超声背向散射技术在心肌病中的应用进展

超声背向散射技术作为一种非侵入性评价组织病理变化类型与程度的定量检测新技术,在评价组织的生理和病理变化方面具有其独特的优势。现就超声背向散射技术的基本原理及其在扩张型心肌病和肥厚型心肌病中的应用进展作一综述。     

Normal Values in Children for Myocardial Ultrasonic Tissue Characterization by Integrated Backscatter

Normal values in adults for ultrasonic tissue characterization by integrated backscatter have been reported previously and subsequently applied to patients with specific diseases. Factors influencing integrated backscatter values in a pediatric population are not clearly defined. To obtain normal values for myocardial ultrasonic integrated backscatter in a pediatric population, we studied 72 children with normal cardiac anatomy using an ultrasonic integrated backscatter imaging system. The parameters measured were at peak, nadir, and end-diastole in eight different regions with two different settings: fixed and variable. We subsequently calculated cyclic variation, the ratios of cyclic variation to end-diastole and to peak. Age ranged from 1 day to 17.4 years (median 4.4 years). More than 90% of data curves from the two regions in the left ventricular posterior wall in long-axis view had normal patterns, whereas more than 50% of curves for the other regions had abnormal patterns. Comparing the two posterior wall positions, there were no differences in cyclic variation between the two regions, with little effect of setting. Less effect of regions and settings was noted for the ratios of cyclic variation to end-diastole or peak. There was no relation between backscatter variables and age, gender, or height, and some variables correlated weakly with body surface area. The assessment of integrated backscatter in children is optimal with interrogation of the left ventricular posterior wall imaged in the long-axis view. More stable estimates are obtained when the cyclic variation is related to the peak or end-diastolic value.     

Ultrasonic Tissue Characterization: Review of an Approach to Assess Hypertrophic Myocardium

It is well known that left ventricular hypertrophy is associated with increased cardiovascular morbidity and mortality. Recently, there has been considerable interest in the application and refinement of noninvasive diagnostic techniques for identification of myocardial tissue composition to permit differentiation between left ventricular hypertrophy that may be associated with irreversible, and therefore, possibly adverse, collagen accumulation ("pathological hypertrophy") as opposed to the type of possibly "benign" hypertrophy devoid of such characteristics (i.e., "physiological hypertrophy"). We review the current state of knowledge in the application of ultrasonic tissue characterization that addresses this question with respect to left ventricular myocardium.     

Ultrasonic tissue characterization and Doppler tissue imaging in the analysis of left ventricular function in essential arterial hypertension: a preliminary study

It is not known if diastolic abnormalities are independent of systolic dysfunction in arterial hypertension. We studied three groups of 10 male subjects of comparable mean age (31.6 +/- 3.5 years), weight, and height: Athletes (A) (cyclists), essential hypertensive patients (H), and controls (C). Ultrasonic myocardial integrated backscatter signals (IBS) of the septum and the posterior wall were analyzed, while the systo-diastolic variation of the backscatter was considered as a cyclic variation index (CVI(ibs)). Myocardial velocities across the left ventricular major axis were sampled at septum and lateral wall levels by pulsed-wave Doppler tissue imaging (DTI). CVI(ibs) at the septum and the posterior wall were significantly lower in the hypertensive group in comparison with athletes and controls, who were comparable. Early diastolic myocardial velocity (E(m)) of the lateral wall and of the septum were significantly lower in hypertensives, while the late diastolic myocardial velocity (A(m)) was significantly higher in hypertensives in comparison with athletes. The E(m)/A(m) at the septum level was significantly lower in hypertensives in comparison with athletes and controls. Significant correlations were found between CVI and DTI parameters: CVI(ibs) and E(m)/A(m) septum (r = 0.50, P < 0.002). Furthermore, significant correlations were found between mean arterial pressure (MAP) and E(m)/A(m) septum (r = - 0.65, P < 0.001). Ultrasonic tissue characterization with the intrinsic contractility study and the evaluation of the regional diastolic function should, therefore, represent a new integrated diagnostic modality for the evaluation of left ventricular hypertrophied intramyocardial function. This study demonstrated that diastolic abnormalities of left ventricular function, in arterial hypertension, are related and progress with systolic intrinsic dysfunction.     

Right Ventricular Adaptations Along with Left Ventricular Remodeling in Older Athletes

Background: Afterload changes and anatomic interaction between the ventricles cause right ventricle (RV) adaptation along with left ventricle (LV) remodeling. This study was designed to evaluate RV adaptations along with LV remodeling and to determine the effect of aging on both ventricles in a population of older athletes. Methods: Echocardiographic characteristics of 48 endurance trained older athletes were examined by tissue Doppler imaging (TDI) and integrated backscatter (IBS). Results: Mean LV mass index was calculated as 107.8 ± 17.0 g/m² . Twenty-two athletes were > 55 years old. Age was found to be a risk factor for diastolic dysfunction regarding lateral TDI velocities (E_m < A_m) (r = 0.385, P < 0.001). RV long-axis (LAX) diameters were associated with LA volumes and LV masses (r = 0.380, P < 0.01 and r = 0.307, P < 0.05). RV LAX diameters were correlated with RV TDI E-wave (r =−0.285, P < 0.05), RV LAX average, and peak IBS values (r = 0.36, P < 0.05 and r = 0.348, P < 0.05). Conclusions: TDI and IBS are applicable methods to evaluate the relationship between the two ventricles in athletes' heart. Increased RV LAX IBS values indicate increased LV mass and LA volume as a result of RV changes along with LV remodeling. Our data suggest that RV TDI E-wave and average RV IBS values reflect cardiac adaptations of both RV and LV in older athletes.     

Clinical Study of Ultrasonic Tissue Characterization with Integrated Backscatter and Echo Intensity in the Diagnosis of Acute Myocardial Infarction

Objectives The purpose of this study was to determine if the ultrasonic integrated backscatter and echo intensity could be used in clinical diagnosis of acute myocardial infarction. Methods and Results Within 2 weeks after acute myocardial infarction,35 patients underwent ultrasonic tissue characterization from the papillary short-axis view. The cyclic variation of integrated backscatter and echo intensity of three different myocardial regions perfused by left anterior descending coronary artery, left circumflex coronary and right coronary were measured . The value of cyclic variation of integrated backscatter and integrated backscatter and echo intensity ≤half of the highest value of three different myocardial regions on a same view were define as the criteria for diagnosing acute myocardial infarction , and the results were compared with coronary angiography. The sensitivity of diagnosing acute myocardial infarction by both Ultrasonic tissue characterization with integrated backscatter and echo intens     

Tissue Doppler Myocardial Velocity Imaging in Infants and Children—a Window into Developmental Changes of Myocardial Mechanics

In adults, tissue Doppler myocardial velocity imaging (TDI) is a recommended component of routine echocardiography and particularly useful to assess diastolic function of the left ventricle. In contrast, color and pulsed‐wave TDI velocities are less accepted in pediatrics, perhaps due to their strong age dependence in children. This review discusses the strengths and limitations of TDI velocity imaging in the pediatric age group. Myocardial velocities increase during normal childhood heart development, starting from fetal life, and these changes vary by cardiac segment. TDI velocity maturation opens an interesting window into the normal development of myocardial mechanics in childhood, but makes it difficult to interpret data in an individual child. Moreover, there is a wider range of normal for any given pediatric age than in adults. Still, TDI has been useful to monitor systolic heart function in children with cardiomyopathy or after heart transplantation. TDI studies revealed diastolic dysfunction in obese children and in cancer survivors with preclinical anthracycline cardiomyopathy. There is a growing body of studies using TDI to assess right heart function in children with congenital heart disease or pulmonary hypertension. Another potential strength of TDI velocities is the study of myocardial dyssynchrony where color TDI is well suited for rapid pediatric heart rates, even on fetal echocardiogram. Quantitative stress echocardiography with TDI is an emerging application in children that already offered insight into heart function in children with tetralogy of Fallot. Therefore, TDI velocity imaging should become part of the routine assessment of heart function in children.     

冠状动脉粥样硬化斑块组织定征:血管内超声研究现状

传统血管内超声对斑块仅可定性为软斑块、纤维斑块和钙化斑块,利用射频数据尚可分析反射波或背向散射的频谱参数以确定斑块构成信息.虚拟组织学作为一种新的组织超声分析技术,在射频数据分析的基础上通过彩色编码以不同颜色来区分不同的斑块成分,绿色代表纤维组织,黄色代表纤维脂质,白色代表钙化组织,红色代表坏死组织.血管内超声弹性图是评价局部斑块弹性的新技术,该技术基于组织受压产生变形的弹性原理,可用以检出斑块并评价其破裂趋势或弹性物质构成.     

Ultrasonic tissue characterization in patients with dilated cardiomyopathy: comparison with findings from right ventricular endomyocardial biopsy

Aim: The clinical usefulness of integrated backscatter (IB) imaging was compared with right ventricular endomyocardial biopsy for assessing myocardial damage in patients with dilated cardiomyopathy (DCM). Methods: We examined 15 patients with DCM and 20 healthy controls. In addition to the conventional M-mode echocardiographic parameters, we determined the cyclic variation in IB values (CV-IB) obtained from parasternal short axis views of the left ventricle just under the transducer for both the interventricular septum (IVS) and the left ventricular posterior wall (PW). The per cent fibrosis area (%) and the transverse diameter of myocytes (m) were measured in right ventricular endomyocardial biopsy specimens by computer image analysis. To analyze the relationship between pathological findings and CV-IB, we divided patients into four subgroups on the basis of the pathological characteristics of endomyocardial biopsy specimens as follows: degeneration dominant group (n=5), fibrosis dominant group (n=5), dilated phase hypertrophic cardiomyopathy (n=2), and mixed type (n=3). Results: CV-IB in the IVS and the PW was lower in patients with DCM (8.8 ± 2.9, 8.3 ± 2.7dB, respectively) than in normal subjects (14.4 ± 2.9, 13.6 ± 2.6dB, respectively). Biopsy findings showed a mean per cent fibrosis area of 24.0 ± 12.3%, and a mean myocyte diameter of 14.3 ± 2.9m in patients with DCM. CV-IB was correlated with both of these findings: per cent fibrosis area (r=–0.56 in IVS, r=–0.56 in PW) and myocyte diameter (r=0.67 in IVS, r=0.71 in PW). CV-IB was decreased in all DCM subgroups compared with normal subjects, but there was no significant difference between subgroups. Conclusions: CV-IB was correlated with both the extent of fibrosis in myocardial tissue and the myocyte diameter. These findings suggest that ultrasonic tissue characterization is a good indicator of the severity of fibrosis and myocyte atrophy in patients with DCM.     

Assessment of the Systolic Left Ventricular Myocardial Velocity Profile and Gradient Using Tissue Doppler Imaging in Patients with Hypertrophic Cardiomyopathy

To determine the systolic characteristics of the hypertrophied myocardium in patients with hypertrophic cardiomyopathy (HCM), we evaluated the left ventricular [left ventricle (LV)] myocardial velocity profile (MVP) and gradient obtained from tissue Doppler imaging (TDI). Transmural wall-motion velocities in the ventricular septum and LV posterior wall were recorded in 12 patients with asymmetric septal hypertrophy and 12 healthy volunteers, and their profiles and gradients were determined. The maximum systolic myocardial velocity gradient in the ventricular septum was significantly lower in the HCM group than in the control group (0.88 ± 0.35 versus 2.24 ± 0.41; P < 0.001), whereas the gradient in the LV posterior wall was only slightly lower in the HCM group than in the control group (2.69 ± 0.82 versus 3.45 ± 0.96). In the control group, the MVPs in the ventricular septum and LV posterior wall were closely linear, suggesting that the transmural velocity is uniform during systole. MVPs in the ventricular septum and LV posterior wall in the HCM group also were closely linear, whereas the distribution of velocities in the ventricular septum was fairly dispersed compared with the control group. The myocardial velocity gradient on the right ventricular side of the ventricular septum decreased or disappeared in the patients with HCM, suggesting a nonuniform distribution of velocities. In conclusion, the MVP and gradient obtained from TDI may represent new indices for evaluating regional LV contractile abnormality in patients with HCM.     

Abnormal Ultrasonic Tissue Characterization of the Myocardium in Children Receiving Doxorubicin for Cancer Therapy

Ultrasonic tissue characterization by integrated backscatter is a sensitive tool to detect myocardial changes related to specific diseases. Cardiotoxicity related to doxorubicin use is well known and remains a major concern. To determine if ultrasonic tissue characterization of the myocardium is abnormal in patients receiving doxorubicin, we studied the myocardium of pediatric patients receiving doxorubicin by a real-time integrated backscatter (IB) imaging system. Three values of IB parameters were averaged from the left ventricular posterior wall at the level of the tip of the mitral valve. In addition to standard echo parameters, we obtained the following IB parameters: peak, nadir, cyclic variation (CV), end-diastole, heart-rate corrected delay of nadir (Delay_c), and the ratio of CV over end-diastole. IB parameters were normalized as Z scores from multiple linear regression equations including echo wall thickness and functional indices from a normal control group of 72 children. We evaluated 27 patients at a median age of 11.6 years (1.6 years to 20.3 years) and median time of 1.7 m (2 days to 7.2 years) after a mean cumulative dose of doxorubicin of 188 ± 120 mg/m² for treatment of neoplasm. Mean (± SD) Z scores for IB variables were as follows: zPeak 0.15 ± 1.07, P = 0.47; zNadir 0.41 ± 1.16, P = 0.08; zCV -0.49 ± 0.95, P = 0.01; zEnd-diastole 0.17 ± 0.94, P = 0.38; zDelay_c 0.33 ± 0.80, P = 0.06, and zCV/Peak -0.59 ± 1.06, P = 0.009. This study shows that ultrasonic IB of the myocardium of children receiving doxorubicin is abnormal and is independent of the cumulative dosage of doxorubicin or the amount of time since the last dose.     

Myocardial blood flow in dilated cardiomyopathy

Myocardial blood flow (MBF) impairment has been documented in advanced idiopathic dilated cardiomyopathy (IDC) where different factors may secondarily affect myocardial perfusion. In failing hearts, explanted from patients with end-stage IDC, MBF is markedly depressed; however, a preferential flow to the subendocardium is preserved; furthermore, the severity of perfusion impairment does not correlate with the extent of fibrosis quantitatively determined by biochemical assessment or evaluated by histologic criteria. Thus, other mechanisms, besides myocardial hemodynamic and structural derangement, seem to operate in determining resting MBF impairment in advanced IDC. Abnormalities in the absolute levels of myocardial perfusion and in regional MBF distribution can also be detected in an early phase of IDC preceeding the development of severe ventricular dysfunction and the clinical appearance of overt heart failure. In patients with subclinical IDC, regional and global myocardial perfusion, as evaluated by positron emission tomography, is frequently impaired both at rest and in response to different vasodilating stimuli such as pacing tachycardia, dipyridamole or adenosine infusion. The presence of an additional coronary resistance, at the microcirculatory level, not sensitive to adenosine, is a possible mechanism causing depressed MBF in subclinical IDC. Progression of the discase is associated with a further impairment in myocardial perfusion.     

Factors associated with non-adherence to therapy with warfarin in a population of chronic heart failure patients

BACKGROUND: Adherence to heart failure therapy is important in reducing morbidity and mortality over the course of the disease process. The aim of this study was to examine factors associated with non-adherence to warfarin in chronic heart failure patients. METHODS: Eighty patients receiving warfarin therapy in 2002 were included. Adherence was defined as maintenance of international normalized ratio (INR) between 2 and 3.5 and keeping scheduled appointments for INR checks at least 75% of the time. Clinical variables examined included age, gender, race, insurance, left ventricular ejection fraction (LVEF), etiology, New York heart association (NYHA) class, comorbidities, smoking, and alcohol use. RESULTS: Of 80 patients studied, 59 were male with mean age ( +/- standard deviation) 52 +/- 13 years, 24 had ischemic etiology with mean LVEF of 24% +/- 9%. Non-adherence was associated with tobacco use, odds ratio of 6.5 (p <0.01). Ischemic etiology was associated with adherence, odds ratio of 4.5 (p <0.01). Non-adherent patients were more likely to be insured with Medicare/Medicaid (p = 0.04) and have better NYHA class (p = 0.04). Adherence positively correlated with older age and lower LVEF, and negatively correlated with number of hospitalizations (p<0.01 for all). In a multiple regression model, patients with improvement in LVEF had decreased adherence over the year (p<0.01). CONCLUSIONS: The profile of heart failure patients who demonstrated non-adherence to warfarin therapy included younger age, nonischemic etiology, better NYHA class, smoking, insurance with Medicare/Medicaid and improved LVEF over the study. Measures targeting these patients may result in improved adherence to other pharmacologic treatments of heart failure.     

Tissue characterization with intra-arterial ultrasound: Special promise and problems

Although we are able to identify many tissue types based on the screen image in intravascular ultrasound, there is additional information in the ultrasound signal which could be of assistance in characterization and identification of tissue. Intravascular ultrasound has several special characteristics which affect tissue characterization. These include the high transducer frequency, small transducers, short and relatively uniform path to the tissue, and limited tissue types to identify. These characteristics influence the results obtained by absolute backscatter, local statistics, frequency dependent backscatter, and angle dependency of backscatter. These effects are both positive and negative, and in many cases can be observed in clinical imaging. Another area of tissue characterization which can be performed with ultrasound is measurement of arterial wall elasticity. This can be of importance in the evaluation of mechanisms of dilatation, and the potential for complications.     

Heart transplant for dilated cardiomyopathy associated with polymyositis

Cardiac involvement is one of the most significant factors in the poor clinical outcome of polymyositis. The case of a 39 year old African American woman with polymyositis, cardiomyopathy, and severe heart failure who had orthotopic heart transplantation is described. Review of the literature reveals that cardiac manifestations of polymyositis are frequent and include conduction system abnormalities, myocarditis, cardiomyopathy, coronary artery atherosclerosis, valvar disease, and pericardial abnormalities.


Keywords: polymyositis; cardiomyopathy; heart failure; heart transplantation     

Serum markers of angiogenesis and myocardial ultrasonic tissue characterization in patients with dilated cardiomyopathy

BACKGROUND AND AIMS: It has been proven that a disturbance in angiogenesis contributes to the progression of myocardial interstitial fibrosis in idiopathic dilated cardiomyopathy (DCM). This study was designed to evaluate the relationship between serum activity of angiogenic factors and myocardial ultrasonic tissue characterization in patients with DCM. METHODS AND RESULTS: We studied 30 patients with DCM and 15 healthy control subjects. Serum levels of vascular endothelial growth factor (VEGF), interleukin (IL)-4 and IL-13 were measured using enzyme-linked immunosorbent assay. We determined calibrated myocardial integrated backscatter (IB) as the value of myocardial interstitial fibrosis using ultrasonic tissue characterization and also quantified the magnitude of cyclic variations in IB (CV-IB). Serum levels of VEGF and IL-13 were significantly higher in patients with DCM than in control subjects (both P<0.05). Calibrated IB was significantly higher and CV-IB was markedly lower in patients with DCM than in control subjects (both P<0.01). In patients with DCM, the levels of IL-13 significantly correlated with calibrated IB (r=0.520, P=0.018). In addition, there was a significant negative correlation between levels of VEGF and CV-IB (r=-0.611, P=0.007). CONCLUSION: The increase in serum VEGF and IL-13 may be closely related to alterations in myocardial texture in DCM.