Usefulness of free-angle M-mode echocardiography in assessing left ventricular dimension and left ventricular systolic function

Objectives To assess the usefulness of free-angle M-mode echocardiography in measuring left ventricular (LV) dimension and global systolic function. Background The validity of conventional M-mode echocardiography in assessing LV dimension and global systolic function is well known; the incidental angle between the M-mode cursor and true LV minor axis diameter, however is a potential cause of measurement error. Free-angle M-mode echocardiography may overcome the limitation of M-mode cursor arrangement in conventional M-mode echocardiography. Methods Thirteen normal volunteers and 10 patients in whom abnormal left ventricular wall motion was not detected by echocardiography (mean age, 53±17 years) were enrolled in this study. Conventional and free-angle M-mode echocardiographic images of the LV were obtained by echocardiography (ALOKA SSD-5500) using a 2.5-MHz transducer, and the LV end-diastolic (LVDd) and end-systolic (LVDs) dimensions were measured by the leading edge method. LV end-diastolic and end-systolic volumes were calculated using a formula by Teichholz, and the LV ejection fraction (LVEF) was obtained. Data from conventional M-mode echocardiography and free-angle M-mode echocardiography were then compared. Results Measurements obtained with conventional M-mode and free-angle M-mode echocaardiography were strongly correlated. Correlation coefficients for LVDd, LVDs, and LVEF were 0.98, 0.98, and 0.96, respectively (p<0.001 in each case). Conclusions Assessment of left ventricular dimension, and global systolic function with free-angle M-mode can be as accurate as conventional M-mode in subjects in whom left ventricular wall motion abnormality is not detectable by echocardiogram. Moreover, when there is improper M-mode cursor direction in conventional echocardiography, free-angle M-mode echocardiography can assess global left ventricular systolic function more accurately and conveniently than conventional M-mode echocardiography.     

Left ventricular involvement in arrhythmogenic right ventricular cardiomyopathy - a scintigraphic and echocardiographic study

BACKGROUND: Left ventricular involvement in arrhythmogenic right ventricular cardiomyopathy (ARVC) is a common finding in autopsy studies. In clinical studies using myocardial scintigraphy, MRI and echocardiography, contradictory results have been reported. In this study, we therefore investigated a group of 15 patients with ARVC using thallium-201 (Tl) single-photon emission tomography (SPECT) and echocardiography including assessment of mitral annular motion with M-mode and pulsed tissue Doppler. METHODS: Exercise and rest Tl-201 SPECT were performed in 15 patients with ARVC. The time from diagnosis of the disease varied from less than 1-16 years. All patients fulfilled the established diagnostic criteria for ARVC. An echocardiographic examination, including assessment of left and right ventricular motion and measurements of the mitral annulus motion with M-mode and pulsed tissue Doppler was performed in the patients and in 25 normal subjects. RESULTS: Tl-201 uptake defects in the left ventricular myocardium were present in all except one patient (93%). The uptake defects were predominantly located to the anteroseptal and basal posterior segments. Wall motion abnormalities were seen in the same segments, and in addition to this, in the septal area. In line with this, the total amplitude and the peak systolic velocity of mitral annular motion at the septal point were significantly decreased in the patients compared with the control group. CONCLUSIONS: Our data show that left ventricular involvement is common in ARVC. Tl-201 SPECT and echocardiographic abnormalities were seen not only in patients with long-lasting symptoms but also in asymptomatic patients and in those with short duration of symptoms.     

Illusion of contraction from out-of-plane translation: can Doppler tissue velocities resolve it?

BACKGROUND: Assessment of wall motion is one of the most challenging aspects of echocardiography. Because of tapering cardiac shape, the impression of thickening can be produced by cardiac translation perpendicular to the image plane. Doppler tissue imaging (DTI) can potentially resolve this problem because in noncontracting myocardium, velocities (V) are uniform (V gradient [VG] = 0) and V measured by DTI should be unaffected by translation perpendicular to the imaging beam. METHODS: A left ventricle-shaped phantom and a string model were translated at known angles to the ultrasound beam. Two-dimensional gray-scale, DTI, and M-mode images were acquired and analyzed. RESULTS: During translation perpendicular to the image plane, 2-dimensional and M-mode images of the ventricular model showed apparent wall thickening, but analysis of the DTI images showed that V and VG across the walls were near 0 (V = 0.04 +/- 0.1 cm/s; VG = 0.02 +/- 0.02/s). Translation of both models at various angles relative to an M-mode beam also created the impression of wall thickening. However, DTI accurately measured the angle-corrected V component toward the transducer (r > 0.98, P <.0001), and VG corresponded to rigid body motion (0.003 +/- 0.02/s). CONCLUSIONS: M-mode and 2-dimensional echocardiography images are subject to the illusion of myocardial thickening resulting from out-of-plane translation. Analysis of tissue Doppler V avoids such error by accurately measuring V components and VG, and it has the potential to improve assessment of left ventricular function.     

Digital recording, display, and storage of echocardiograms

Digital acquisition, display, and storage are new options available for handling echocardiographic images. These types of image management offer many practical advantages and are excellent supplements to standard videotape recordings. For routine M-mode and Doppler studies this digital approach, when combined with videotape, can virtually eliminate the necessity for strip chart recordings. Probably the principal advantage of digital storage techniques is for two-dimensional echocardiography. The continuous loop display is extremely convenient for rapid review, quantitation, and serial studies. When considering the implementation of these techniques, there are many limitations and practical considerations that must be kept in mind. Recording two-dimensional echocardiograms in a continuous loop mode requires that the same number of frames or cells must be used if one wants to display more than one image simultaneously. When creating a continuous loop of a single cardiac cycle, the number of cells and the interval between cells are greatly influenced by the heart rate. One must be able to display simultaneous images with varying heart rates. Last, the number of cells, the resolution, and the gray scale determine the amount of digital information that has to be stored, retrieved, or transmitted. The cost and size of the medium and the speed with which the images can be retrieved or transmitted become factors in how one elects to digitally acquire this information. One approach that has been used, which seems to work quite well in most cases, is to use an eight-cell sequence for two-dimensional echocardiograms. When primarily interested in looking at ventricular function, especially regional wall motion, a 50 msec interval between frames is most appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)     

The use of echocardiography in Wolff–Parkinson–White syndrome

Endocardial mapping and radiofrequency catheter ablation are well established modalities for the diagnosis and treatment of patients with Wolff–Parkinson–White (WPW) syndrome associated with tachyarrhythmias. However, the electrophysiologic techniques are invasive, require radiation exposure, and lack spatial resolution of cardiac structures. A variety of echocardiographic techniques have been investigated as a non-invasive alternative for accessory pathway localization. Conventional M-mode echocardiography can detect the fine premature wall motion abnormalities associated with WPW syndrome. However, it is unable to identify the exact site of accessory pathway with sufficient accuracy. 2D, 2D-guided M-mode, and 2D phase analysis techniques are limited by image quality and endocardial border definition. Various modalities of tissue Doppler echocardiography significantly increase the accuracy of left-sided accessory pathway localization to 80–90% even in patients with poor acoustic window. However, right-sided pathways remain a diagnostic challenge. Strain echocardiography by speckle tracking has recently been evaluated and appears promising. Different cardiac abnormalities have been detected by echocardiography in WPW patients. Patients with WPW syndrome and tachyarrhythmias have impaired systolic and diastolic function which improves after radiofrequency ablation. Echocardiography is useful in identifying patient with accessory pathway-associated left ventricular dyssynchrony and dysfunction who may benefit from ablation therapy. Transesophageal and intracardiac echocardiography have been used to guide ablation procedure. Ablation-related complications detected by routine echocardiography are infrequent, rarely clinically relevant, and of limited value.     

Ultrasound beam orientation during standard two-dimensional imaging: assessment by three-dimensional echocardiography.

Standard two-dimensional echocardiographic image planes are defined by anatomic landmarks and assumptions regarding their orientation when these landmarks are visualized. However, variations of anatomy and technique may invalidate these assumptions and thus limit reproducibility and accuracy of cardiac dimensions recorded from these views. To overcome this problem, we have developed a three-dimensional echocardiograph consisting of a real-time scanner, three-dimensional spatial locater, and personal computer. This system displays the line of intersection of a real-time image and an orthogonal reference image and may be used to assess actual image orientation during standardized two-dimensional imaging when the line-of-intersection display is not observed by the operator. Three hundred forty standard images were assessed from 85 examinations by 11 echocardiographers. Twenty-four percent of the unguided standard images were optimally positioned within +/- 5 mm and +/- 15 degrees of the standard. Of the optimal images, two thirds were parasternal long-axis views. A subsequent study with three-dimensional echocardiography and line-of-intersection guidance of image positioning showed 80% of the guided images to be optimally positioned, a threefold improvement (p < 0.001). Two-dimensional echocardiography does not achieve reasonably consistent optimal positioning of standard imaging views, suggesting that measurements taken from these views are likely to be suboptimal. Three-dimensional echocardiography that uses line-of-intersection guidance improves image positioning threefold and should therefore improve the accuracy and reproducibility of quantitative echocardiographic measurements derived from these images.     

A comparison of left atrial size by two-dimensional transthoracic echocardiography and magnetic endocardial catheter mapping

This study sought to validate the accuracy of magnetic electroanatomic mapping (MEAM) for determining cardiac chamber size in a clinically relevant situation. The authors chose to compare LA size measured by MEAM to that assessed by two-dimensional guided M-mode echocardiography. The study included 37 patients with drug refractory paroxysmal atrial fibrillation who underwent two-dimensional echocardiography and a detailed MEAM of the LA. The entire LA was mapped with a mean of 132 +/- 50 points with attention to identifying the mitral annulus and posterior wall of the LA. The MEAM measurement of LA size was taken as the distance from the anterior wall of the LA to the posterior wall in a plane parallel to the mitral valve annulus at atrial end-diastole. LA dimension determined by M-mode echocardiography was assessed in a plane parallel to the mitral valve annulus in the parasternal long-axis view during atrial end-diastole. LA size assessed by M-mode echocardiography was 41.2 +/- 5.0 versus 40.9 +/- 4.5 mm as assessed by MEAM, with good correlation (r = 0.87, P < 0.001). Only three patients had a difference in LA size that was > 0.3 cm between the two measurement techniques. Thus, it appears that LA anteroposterior dimension as determined by electroanatomic mapping is similar to that determined by two-dimensional guided M-mode echocardiography. MEAM appears to be an accurate method by which LA size can be assessed in patients with drug refractory atrial fibrillation undergoing left atrial ablation procedures.     

In vitro simulation and quantification of temporal jitter artifacts in ECG-gated dynamic three-dimensional echocardiography

The image quality of dynamic 3-D echocardiography is limited by temporal jitter artifacts that result from the asynchronous acquisition of video frames with the cardiac cycle. This paper analyzes the source and extent of these artifacts using in vitro studies. Dynamic 3-D images of a myocardial motion phantom were reconstructed and analyzed for eight cardiac motion patterns. The extent of temporal jitter artifacts was quantified, first, from the images by computing temporal jitter maps and, second, predicted from the motion waveforms. Temporal jitter appeared as a pattern of streak artifacts converging at the axis of rotation of the imaging plane, for the rotational scanning approach used in our study. The results of the experimental analysis techniques were compared with the waveform analysis using linear regression analysis. The least squares line showed good correlation between the data (r > 0.9) and its deviation from the line of identity was calculated to be <9%.     

Right and left ventricular long-axis function in the fetus using angular M-mode.

OBJECTIVE: Long-axis function is determined by the longitudinally oriented myocardial fibers. Postnatally, conventional M-mode is used to assess tricuspid and mitral valve ring movements in relation to the cardiac apex. During fetal life, this is precluded by variable fetal position. We assessed the feasibility of determining right and left ventricular long-axis function in the fetus. METHODS: A prospective, pilot study. The four-chamber view obtained during routine fetal echocardiography was recorded in a cineloop to which B-mode guided M-mode echocardiography was applied using angular M-mode. This allowed retrospective and correct placement of the cursor line from cardiac apex to tricuspid or mitral valve rings. M-mode tracings of the valve ring movements in relation to the apex were derived from the originally stored loop. Data from 18 fetuses (17-29 weeks of gestation) were available for analysis. Total excursion of the valve rings was measured offline. A second cursor line was simultaneously placed in the left ventricular outflow tract during color flow mapping for timing purposes (n = 6). RESULTS: Right and left ventricular long-axis recordings were obtained in 18 and 14 cases, respectively. Total right ventricular excursion was 5.2 mm (SD, 0.9 mm) (range, 3.9-7.2 mm). Total left ventricular free wall excursion was 4.5 mm (SD, 1.1 mm) (range, 3.0-6.8 mm). For paired data, the mean of differences (right ventricle-left ventricle) was 0.8 mm (95% confidence interval 0.5-1.2). The valve rings moved towards the apex during systole (shortening) and away from it during diastole (lengthening). Peak downward movement coincided with cessation of aortic flow and diastolic lengthening with flow through the atrioventricular valves. CONCLUSION: Long-axis function in the fetus is feasible if M-mode angle correction is used. There was no clinically significant difference between tricuspid and mitral valve excursions. The pattern of atrioventricular valve movement is coordinate and similar to that of adults. Long-axis function offers a new avenue to study systolic and diastolic function in the fetus.     

Automatic detection of inter-frame motion in echocardiographic images

Signal averaging of echocardiographic frames acquired over multiple cardiac cycles has been used to improve image quality. However, misalignment of frames from respiration, transducer or patient movement, and irregular cardiac contraction affects the quality of the resultant averaged image. A motion detection system has been developed using inter-frame subtraction and statistical pattern recognition techniques. Automatic selection of frames exhibiting significant motion in a canine cardiac model compare favorably to manual selection by cardiologists (phi = 0.94) in a test set of 103 images. This method, combined with signal averaging, has resulted in an improvement in image quality.     

Echocardiographic design of a multicenter investigation of free-living elderly subjects: the Cardiovascular Health Study.

The Framingham study has shown by M-mode echocardiography that left ventricular hypertrophy is a powerful, independent predictor for the development of coronary heart disease and that increased left atrial dimension has been associated with an increased risk of stroke. No previous population-based study has evaluated the risk factor correlates and predictive value for coronary heart disease and stroke of two-dimensional and Doppler, as well as M-mode, echocardiography. The Cardiovascular Health Study is a multi-year prospective epidemiologic study of 5201 men and women older than 65 recruited from four geographic sites in the United States. The main objectives of incorporating echocardiography were to determine whether echocardiographic indices, or changes in these indices, are (1) correlated with traditional risk factors for coronary heart disease and stroke; and (2) independent predictors of morbidity and mortality for coronary heart disease and stroke. Echocardiographic measurements of interest include those related to global and segmental left ventricular systolic and diastolic structure and function and left atrial size. For each subject, a baseline echocardiogram was recorded in super-VHS tape using a standard protocol and equipment. All studies were sent to a reading center where images were digitized and measurements were made using customized computer algorithms. Calculated data and images were stored on optical disks to facilitate retrieval and future comparisons in longitudinal studies. A second echocardiogram is scheduled in year 7, with a goal of determining whether changes in cardiac anatomy or function over a 5-year period are important predictors of morbidity or mortality from coronary heart disease and stroke. Quality control measures included standardized training of echocardiography technicians and readers, technician observation by a trained echocardiographer, periodic blind duplicate readings with reader review sessions, phantom studies, and quality control adults.     

Feasibility of detailed M-mode echocardiographic examination in markedly obese adults: Prospective study of 50 patients

A study that investigated the applicability of M-mode echocardiography in a group of obese adults who were referred to the clinical echocardiographic laboratory is summarized. The M-mode echocardiographic imaging technique, as performed with currently available equipment, permitted visualization of the cardiac anatomy in a majority of the patients. Comparable clinical information may be difficult to obtain by other methods.     

Assessment of colour doppler tissue imaging using test-phantoms

An investigation has been carried out on the velocity resolution, spatial resolution and accuracy of Doppler images as part of a study into the Doppler display of cardiac tissue motion. Test-phantoms were designed to perform this work and images were captured on a computer. The characteristics of the phantom images and of the image capture process were studied. The smallest spatial detail that was observed in the Doppler image was 3 mm by 3 mm. Doppler receive gain and Doppler ensemble size both affected velocity resolution. Different target materials gave different measures for velocity resolution. This could be related to the different back-scatter intensities of the materials.     

人体心脏运动对多普勒血流速度频谱测定的影响

目的 观察多普勒血流速度频谱上的心脏运动性多普勒频移信号的幅度是否有真正代表心脏局部运动的速度,进而为纠正血流速度频谱中血流速度测量误差提供方法。方法 以心尖部为探测点,主动脉瓣环处M型超声心动图不同相位的最大运动速度为标准,观察主动脉瓣口多普勒血流速度频谱中相应相位的心脏运动性多普勒频移信号的峰值速度是否与M型测得者相关。结果 心脏运动性多普勒频谱领带不同相位的峰值运动速度与M型超声心动图所测得的相应相位的最大运动速度相关非常显著,r＝0．99。结论 根据本研究和体外模拟实验研究,血液通过各瓣口的真实峰值血流速度为血流速度频谱显示的最大血流速度与心脏运动性多普勒频移信号的峰值速度之和。     

多平面经食管三维超声心动图测量左室心肌重量的实验研究

为了探索定量评价左室肥厚的新方法，本文采用多平面经食管超声心动图三维重建系统，测量了18只实验犬冠状动脉结扎前后的在体心脏左室心肌重量（LVM），并以LVM的解剖学测值为标准对照，与M-型超声Penn氏方法进行了比较。结果显示，冠状动脉结扎前，三维超声心动图（3DE）及Penn氏方法的LVM测值均与其实测值取得了高度相关（r分别为0.95，0.91，SEE分别为2.1g，3.6g），两种方法所测LVM与其实际值间均无显著性差异（P均＞0.1）;冠状动脉结扎后，Penn氏方法的测量结果与LVM实际值的相关性显著下降（r=0.63，SEE=7.9g），而3DE方法的测值仍与LVM的解剖学测值保持高度相关（r=0.96，SEE=2.2g）。表明：3DE可准确测量LVM，且不受左室几何形状的影响，因而在评价高血压合并冠心病患者心肌肥厚时，较之传统的M-型超声Penn氏方法具有显著的优越性。     

Real-time cross-sectional echocardiographic diagnosis of infiltrative cardiomyopathy due to amyloid

We report the real-time cross-sectional echocardiographic findings in a case of cardiac amyloidosis. Alterations in cardiac structure and function previously demonstrated by M-mode echocardiography were also demonstrable on cross-sectional examination. A new finding of an altered pattern of myocardial echoes detected by cross-sectional echocardiography alone is described.     

Adaptive brightness transfer functions in echocardiography

Despite the clear advantages of echocardiography as a diagnostic tool, its images tend to be noisy and unclear. This paper presents an innovative algorithm, called ABTF (adaptive brightness transfer function), designed to optimally adjust the gray-levels used in echocardiography. The algorithm is aimed at aiding in visual tissue classification and texture-based visual tissue tracking in echocardiographic images. The ABTF method is based on fitting the cine-loop's gray-level histogram to a sum of three Gaussian functions, each of which relates to a different region within the image, the left ventricular cavity, the relatively dark regions within the cardiac muscle and the bright regions within the cardiac muscle. The procedure's feasibility has been supported by a test-set, including 23 echocardiographic cine-loops from 10 different patients. The resulting image quality appears to be superior to that of the original images, tending to show better contrast and a higher dynamic range of gray-levels within the cardiac muscle. According to two expert cardiologists, who have blindly ranked the image quality of each cine-loop on a scale from 1 to 10, where 10 corresponds to the highest possible image quality, the mean score of the original cine-loops is 7.1 +/- 1.1, while the mean score of the cine-loops to which ABTF has been applied is 8.0 +/- 1.2.     

Cardiac motion and strain detection using 4D CT images: comparison with tagged MRI,and echocardiography

Ischemic heart disease is a leading cause of death in the modern world. Coronary obstruction is the basis for ischemic heart disease and leads to decreased cardiac supply and decreased contractility of the myocardium. Recently, high quality 4D computed tomography (CT) has become available for cardiac imaging and provides the clinician with high quality anatomical images. In this article, a new method is proposed to detect 3D motion and strain from 4D cardiac CT images by constraining intensity constancy, myocardial volume changes and motion smoothness assumptions. The proposed method is validated by using manual tracking of the cardiac CT landmarks. The average error for the manual tracking, by an expert, was 2.9 ± 0.9 mm. As an additional validation, the cardiac CT strain values were compared to the cardiac tagged magnetic resonance imaging (MRI) and 2D B-mode echocardiography strain values of the same patients. The correlation ratio was significantly high for CT and tagged MRI radial strain values (r = 0.76, 95 % confidence interval, P < 0.001). The correlation ratio was meaningful for CT and echocardiography radial strain values as well (r = 0.67, 95 % confidence interval, P < 0.001). The correlation ratio for CT and tagged MRI circumferential strain values was acceptable (r = 0.73, 95 % confidence interval, P < 0.001), while the correlation ratio for CT and echocardiography circumferential strain values was good as well (r = 0.61, 95 % confidence interval, P < 0.001). In general, motion and strain values computed from cardiac CT images agree with motion and strain values computed from tagged MRI and echocardiography images.     

Assessment of the normal adult right ventricular diastolic function using M-mode echocardiographic measurement of tricuspid ring motion

Right ventricular function can be evaluated echocardiographically by assessing the longitudinal motion of the tricuspid ring recorded in the apical four chamber view. In this study, we applied this technique to assess the right ventricular diastolic function in 10 healthy Japanese men (mean age : 28±6 years; age range : 20–43 years). Echocardiographic studies were performed with a phased-array imaging system using a 2.5 MHz probe. Tricuspid ring motion was measured by two-dimensional echo guided M-mode echocardiogram of the right lateral tricuspid ring. The excursion of the tricuspid ring during early diastole (dS; mm) and the peak rate of change of the excursion (dS/dt; mm/sec) were measured. We also assessed the right ventricular function by cine magnetic resonance imaging (MRI). Cine gradient echo images were obtained along the short axis of the right ventricle. The right ventricular volume at each phase of the cardiac cycle was calculated by Simpson's method and time–volume curves were constructed. The peak filling rate (dV/dt; ml/s) was determined from these time–volume curves. The dS was 12.8±2.5 mm, dS/dt was 132±27 mm/sec and dV/dt was 269±66 ml/s. There were significant positive correlations between dS and dV/dt (r=0.80, P<0.01), and between dS/dt and dV/dt (r=0.45, P<0.05). Based on our results, M-mode echocardiographic measurements of tricuspid ring motion may be used to assess the right ventricular diastolic function.     

Improved cardiac anthropomorphic phantom.

An improved cardiac sonographic phantom is described that simulates the anatomy of the human heart for applications as a low cost quality assurance and training tool in echocardiography. The major new feature in the phantom is the development of a polyurethane sponge left ventricle, which mimics the myocardium during sonographic imaging while undergoing hydraulic pumping. The left ventricle, including prosthetic mechanical mitral and aortic valves, is housed in an optically transparent Lexan chamber or in a tissue mimicking polyurethane rubber torso. Additional new features include a port for transesophageal imaging, and an adjustable calibrated stroke volume on the piston pump, which can serve as a standard for echocardiographic stroke volume measurement. B-scans of the phantom show excellent image quality in all three standard echocardiographic views as well as in transesophageal scanning.