Digital subtraction high-frame-rate echocardiography in detecting delayed onset of regional left ventricular relaxation in ischemic heart disease

Stress echocardiography: a useful tool for children with aortic stenosis

The development of echocardiographic ventricular wall motion abnormalities and ST segment changes with exercise may enhance the detection of myocardial ischemia in children with aortic valve stenosis (AS). This study aimed to assess the relationship between the exercise wall motion index (WMIe), ST segment depression (STd), and overall functionality in asymptomatic children with isolated AS. A prospective interpretation of collected stress echocardiographic images was performed. The 98 children who met the inclusion criteria had a mean age of 12.8 years and a male/female ratio of 4/1. Group 1 (mild AS) was composed of 70 children, and group 2 (moderate or severe AS) was composed of 28 children. Abnormal WMIe was seen in 8 patients (5 in group 1 and 3 in group 2), and significant STd was observed in 13 children (3 in group 1 and 10 in group 2). Four (50 %) of the eight patients with abnormal WMIe also had significant STd. Severity of stenosis was associated with STd (odds ratio [OR], 12.0; 95 % CI 3.0-49.0), logistic regression). A significant association also existed between abnormal WMIe and STd (OR, 9.0; 95 % CI 1.9-42.0, logistic regression). Exercise duration was significantly shorter in group 2 (12 ± 4.52 min) than in group 1 (13 ± 5.28 min) (p = 0.02, analysis of covariance). The appearance of wall motion abnormalities and STd during exercise may be helpful in detecting inducible, functionally important myocardial ischemia in asymptomatic children with AS. Stress echocardiography may be a useful adjunct to more traditional exercise testing in risk stratifying asymptomatic children with AS.

Persistence of systolic and diastolic regional dysfunction after brief episodes of myocardial ischemia evaluated with velocity vector imaging

BACKGROUND

The time course and characteristics of persistent regional dysfunction after ischemia remain unclear. Velocity vector imaging (VVI) allows accurate quantification of regional myocardial function. The aim of this study was to characterize the time course of regional diastolic and systolic abnormality after recovery from different durations of ischemia by VVI.

METHODS

72 rats underwent brief left coronary occlusion (3, 5, 10 and 15 min, respectively) followed by reperfusion for 4-8h. Hemodynamic measurements and VVI were performed at various time points. Regional systolic and diastolic functions were estimated from peak diastolic and systolic circumferential strain rate (SR-d and SR-s) of the left ventricle, respectively.

RESULTS

Both SR-d and SR-s were significantly decreased in the ischemic segment during occlusion compared to non-ischemic segment. With the increase in occlusive time, the duration of reduced SR-d and SR-s after reperfusion was prolonged. Both SR-d and SR-s returned to pre-occlusion values in less than 30 min after reperfusion in the 3 min and 5 min ischemia groups. However, in the 10- and 15-min ischemia groups, SR-d did not fully recovered even at 240 min after reperfusion despite complete recovery of SR-s. The left ventricular hemodynamics during occlusion were significantly changed in all groups and returned to baseline immediately after reperfusion.

CONCLUSION

The persistence of diastolic regional dysfunction is longer than systolic regional dysfunction after a relative longer ischemic event, suggesting that recent myocardial ischemic insult mimicking variant angina may be recognized with the evaluation of regional diastolic function.

The relationship between invasive hemodynamic measurements and tissue Doppler-derived myocardial velocity and acceleration during isovolumic relaxation in healthy dogs

This study investigated the feasibility of using the values of tissue Doppler imaging (TDI)-derived myocardial velocity during isovolumic relaxation (V(IR)) and myocardial acceleration during isovolumic relaxation (ACC) obtained from the left ventricular (LV) free wall to evaluate LV relaxation in normal dogs. Seven dogs were anesthetized, and dobutamine or esmolol was infused at a rate of 5.0 and 10.0 mug/kg/min or 100 and 500 mug/kg/min, respectively, via a cephalic vein. The order of drug administration (dobutamine or esmolol) was assigned to each dog. Simultaneous pulsed-Doppler (PD) echocardiography, TDI and hemodynamic measurements were performed. Compared with the baseline values, dobutamine significantly increased dP/dt min, but significantly shortened tau (tau). Similarly, esmolol significantly decreased dP/dt min, but significantly prolonged tau. Compared with the baseline values, dobutamine significantly increased V(IR) and ACC, and esmolol significantly decreased V(IR) and ACC. Both dP/dt min and tau were significantly correlated with TDI-derived IVRT (r=-0.43 and 0.74), V(IR) (r=0.85 and -0.49) and ACC (r=0.84 and -0.52). These results indicate that the TDI-derived V(IR) and ACC values obtained from the LV free wall can potentially be used to assess LV relaxation in dogs.

Assessment of global and regional left ventricular function after surgical revascularization in patients with coronary artery disease by real-time triplane echocardiography

OBJECTIVE

The purpose of this study was to evaluate the capability of real-time triplane echocardiography (RT3PE) for monitoring global and regional systolic function of the left ventricle (LV) after surgical revascularization and for evaluating the effect of surgery and predicting restenosis.

METHODS

Forty-nine patients underwent RT3PE before and at 10 days and 1, 3, and 6 months after coronary artery bypass grafting (CABG). The global systolic function of the LV was assessed with the parameters of end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), and stroke volume (SV). The regional myocardial deformation was detected by triplane strain rate imaging. Recovery of myocardial function after surgery and the correlation between global and regional function were investigated.

RESULTS

In 41 of the 49 patients, the EDV and ESV decreased, and the EF and SV increased gradually and showed statistical significance at 3 and 6 months after surgery (P < .05; P < .01). The systolic strain rate (SR(sys)) and systolic strain (S(sys)) increased, and the postsystolic strain index (PSI) decreased progressively after CABG, with significant changes in almost all studied segments at 6 months (P < .05; P < .01). In addition, recovery of the SR(sys), S(sys), and PSI at each follow-up stage after surgery correlated well with EF improvement, with a positive correlation between the SR(sys), S(sys), and EF and a negative correlation between the PSI and EF. Restenosis was suspected in the other 8 patients. The sensitivity, specificity, and accuracy of RT3PE to predict restenosis were 75.00%, 89.47%, and 85.19%, respectively.

CONCLUSIONS

Real-time triplane echocardiography can be used to quantitatively assess global and regional myocardial function. It may represent a new, powerful method to monitor improvement of myocardial function after CABG and to predict restenosis.

Detection of left ventricular systolic and diastolic abnormalities in patients with coronary artery disease by color kinesis

BACKGROUND

Color kinesis (CK) is a recently developed echocardiographic technique based on acoustic quantification that automatically tracks and displays endocardial motion in real time and has been used in initial studies to improve the evaluation of global and regional wall motion.

HYPOTHESIS

For further validation of the use of CK for analysis of segmental ventricular dysfunction, we assessed its sensitivity and specificity for detection of regional systolic and diastolic wall motion abnormalities in patients with coronary artery disease (CAD).

METHODS

Two-dimensional (2-D) echocardiography and CK were used to study 15 normal subjects and 63 patients with technically good quality echocardiographic tracings, who underwent coronary arteriography within 1 month of echocardiography. Significant (> 70% luminal diameter stenosis) CAD was present in 50 patients (79%).

RESULTS

Color kinesis tracked endocardial motion accurately in 93% of left ventricular segments. Wall motion score, systolic segmental endocardial motion (SEM), and the time of systolic SEM (tSEM) and diastolic (tDEM) segmental endocardial motion were calculated. Intra- and interobserver variability were within narrow limits. SEM and tSEM were significantly lower and tDEM was significantly higher in the patient population than in the control group (p < 0.001). Comparison between CK and 2-D echocardiography showed a correlation coefficient of 0.81 between the two techniques. The score was identically graded in 74% of segments, with concordance of 82% in diagnosing segments as abnormal. Interobserver concordance was 86% for CK (r = 0.85) and 81% for 2-D echocardiography (r = 0.80). The sensitivity and specificity of systolic and diastolic CK parameters for the detection of CAD were 88 and 92% and 77 and 85%, respectively. The positive predictive values were 93 and 96%, respectively, the negative predictive values were 63 and 73%, respectively, and the overall accuracy was 86 and 91%, respectively.

CONCLUSIONS

Our data suggest that CK is a feasible and sensitive technique for identifying regional systolic as well as diastolic wall motion abnormalities in patients with CAD.

Strain rate imaging pre- and post-percutaneous coronary intervention: a potential role in the objective detection of ischaemia in exercise stress echocardiography

AIMS

To determine the feasibility of strain rate imaging (SRI) in the objective detection of exercise-induced ischaemia.

METHODS AND RESULTS

Sixteen patients undergoing elective percutaneous coronary intervention (PCI) underwent treadmill exercise stress echocardiography (ESE) pre- and post-PCI. Measurement of systolic SRI parameters was attempted in all myocardial segments at baseline, peak stress, and in recovery. Segments were divided into those supplied by target (Group 1) and non-target vessels (Group 2). Percutaneous coronary intervention was successful in all patients. In Group 1, there was no significant difference in post-systolic strain rate (SRps) at baseline or at peak stress but there was significantly greater SRps pre-PCI compared with post-PCI at 30 min into recovery (-0.37 +/- 0.53 vs. -0.07 +/- 0.44 s(-1), P = 0.004). There were similar findings with the SRps index [ratio of SRps:peak systolic strain rate (SRsys)]. Group 2 segments did not demonstrate any significant differences in SRI parameters pre- and post-PCI. At peak exercise pre-PCI, Group 1 segments had significantly delayed time to SRsys compared with Group 2 (0.12 +/- 0.05 vs. 0.09 +/- 0.05 s, P = 0.013), a difference that was abolished post-PCI.

CONCLUSION

This suggests a potential role for SRI in the objective detection of exercise-induced ischaemia by echocardiography at peak stress and during recovery at the time of improved image quality.

Positive Isovolumic Relaxation Velocity Detected by a Spectral Tissue Doppler Mapping Technique as an Indicator of Coronary Artery Disease: A Prospective Study

BACKGROUND

A positive myocardial velocity during isovolumic relaxation phase (V(IR)) detected by spectral tissue Doppler imaging has been shown to indicate ischemic myocardium. We sought to examine the diagnostic value of positive V(IR) for detecting coronary artery disease (CAD) in patients with chest pain and apparently normal left ventricular contraction.

METHODS

A total of 138 patients (74 men, age 69 +/- 8 years) underwent spectral Doppler tissue imaging measurements at the annular and mid left ventricular levels in the apical 4- and 2-chamber views (8 points/patient) at rest in addition to standard echocardiography. Subsequently, patients underwent thallium-201 myocardial perfusion single photon emission computed tomography (n = 98) and/or coronary angiography (n = 60). The duration of positive V(IR) was also assessed. CAD was diagnosed by having more than 75% diameter stenosis in coronary angiography.

RESULTS

CAD was present in 41 patients (30%). The duration of positive V(IR) was distributed from 0 to 280 milliseconds with the median value of 100 milliseconds. Presence of positive V(IR) predicted CAD with sensitivity of 80% and specificity of 61%.

CONCLUSIONS

Positive V(IR) detected by spectral tissue Doppler imaging is a useful indicator of CAD in patients with apparently normal left ventricular contraction and chest pain.

Effects of Postischemic Regional Left Ventricular Diastolic Wall Motion Abnormalities or Delayed Relaxation Following Coronary Vasospasm on Global Diastolic Function

BACKGROUND

Regional left ventricular (LV) diastolic wall motion abnormalities detected by color kinesis (CK), an echocardiographic technique, may be a more sensitive measure to postischemic damage following coronary spasm than parameters of global diastolic function.

METHODS AND RESULTS

Regional LV diastolic wall motion was evaluated by using CK in 18 patients with variant angina on the day following coronary spasm, which was induced by intracoronary acetylcholine. Fractional regional LV cavity area expansion in the short-axis view during the first 30% of the LV filling time, was used to identify postischemic asynchronous diastolic wall motion. Regional delayed relaxation was observed in any of the LV regions in all the patients, who were divided into 2 groups (Group S: 7 patients with single-vessel spasm with regional delayed relaxation in one area. Group M: 11 patients with multivessel spasm or spasm of the proximal left anterior descending branch with regional delayed relaxation in multiple areas). In Group S, no abnormality (0%) was noted in any of the indexes of global diastolic function including the isovolumic relaxation time, the ratio of peak rapid filling to peak atrial filling velocities and the deceleration time. In contrast, in 5 (45%) of the Group M patients, abnormalities were noted in all of those indexes.

CONCLUSIONS

Postischemic regional LV-delayed relaxation following coronary vasospasm was detected sensitively by analysis of CK images. The indexes of global LV diastolic function are insensitive to postischemic damage following single vessel spasm, although they are somewhat sensitive following multivessel spasm.

Diagnosis of multivessel coronary vasospasm by detecting postischemic regional left ventricular delayed relaxation on echocardiography using color kinesis

BACKGROUND

It is not known whether multivessel coronary spasm occurs spontaneously in patients who have variant angina (VA) with demonstrated multivessel spasm induced by intracoronary injection of acetylcholine (ACh). Regional left ventricular (LV) diastolic dysfunction or wall motion abnormality may persist after an episode of coronary vasospasm. Color kinesis (CK) is a recent development that facilitates the echocardiographic evaluation of regional diastolic wall motion.

METHODS AND RESULTS

Regional diastolic wall motion was evaluated using CK in 26 patients with VA within 1 week of the last episode of angina. The LV segmental filling fraction in the short-axis view during the first 30% of the diastolic filling time, expressed as a percentage, was used to objectively identify postischemic diastolic endocardial motion asynchrony. Diastolic asynchrony or regional LV delayed relaxation was noted in all 26 (100%) patients and in 14 (54%) it was detected in multiple vascular territories, suggesting multivessel spasm. Multivessel spasm was induced by ACh in 11 (79%) of the patients with suspected multivessel spasm by CK. In 11 (92%) of the 12 patients with multivessel spasm induced by ACh multiple regions of delayed relaxation had been noted by CK. The regions of delayed relaxation were largely consistent with the territories perfused by the arteries reacting to ACh (sensitivity: 96%, specificity: 91%).

CONCLUSION

ACh induced spasm in the same coronary arteries as those perfusing the regions with delayed diastolic wall motion detected by CK in most of the patients with VA, suggesting that multivessel spasm does occur spontaneously in patients with susceptible arteries.

Anatomic m-mode, a pertinent tool for the daily practice of transthoracic echocardiography

OBJECTIVES

We sought to compare anatomic M-mode (AMM), a new echocardiographic postprocessing option, and conventional M-mode (CMM) using fundamental imaging and tissue harmonic imaging.

METHODS

Transthoracic echocardiography was performed in 15 selected patients to analyze the reproducibility of AMM and in 47 patients to assess its clinical value versus CMM. Acquisitions were performed successively: CMM fundamental imaging; CMM tissue harmonic imaging; tissue harmonic imaging cineloops for AMM; and fundamental imaging cineloops for AMM. Quantitative analysis was performed offline. The angle alpha between the CMM line and the septal endocardial interface was calculated and the expected percentage of error in measuring left ventricular diameter was derived.

RESULTS

AMM analysis was reproducible. Optimal AMM full echocardiographic definition was obtainable in 77% of the population, whereas CMM was optimal for 49% because of scan line misalignment, causing a measurement overestimation exceeding 5%.

CONCLUSION

The ability with AMM to reduce the alpha angle to 0 degrees and, thus, avoid overestimation of left ventricular dimensions might improve follow-up in several pathologic conditions.

Timing of regional left ventricular lengthening by pulsed tissue Doppler

Pulsed tissue Doppler can measure myocardial velocities with high temporal resolution. Our aim was to determine the onset timing of the regional left ventricular longitudinal early lengthening (e) in relation to the mitral inflow (E) in acute coronary syndromes. We applied pulsed tissue Doppler to the septal, lateral, inferior, and anterior left ventricular basal walls of 160 patients with acute coronary syndromes and 60 control subjects. Maximum systolic and early diastolic velocities were lower for patient than for control walls (6.1 +/- 1.7 vs 7.9 +/- 1.4 cm/s, P <.0001, and 6.9 +/- 2.3 vs 10.0 +/- 2.3 cm/s, P <.0001, respectively) and e started later than E (12 +/- 30 vs 2 +/- 19 milliseconds later, P <.0001). All 3 variables related to the degree of visual left ventricular wall pathology. The intraindividual time range for all 4 e starts was wider for patients (43 +/- 27 vs 30 +/- 18 milliseconds, P <.0001). Our results show that pulsed tissue Doppler can identify a delayed and asynchronous initial wall lengthening in acute coronary syndromes.

Diagnosis of coronary vasospasm by detection of postischemic regional left ventricular delayed relaxation using echocardiographic evaluation with color kinesis

BACKGROUND

Coronary vasospasm has been diagnosed by invasive provocative procedures during coronary arteriography. It would be useful to have a reliable, noninvasive, and safe diagnostic method for coronary vasospasm. Regional left ventricular (LV) diastolic dysfunction may persist without systolic dysfunction after an episode of coronary vasospasm. Color kinesis (CK) has been recently developed to facilitate the echocardiographic evaluation of regional wall motion.

HYPOTHESIS

Color kinesis may be useful for diagnosis of coronary vasospasm by detection of postischemic regional LV diastolic wall motion abnormality.

METHODS

Fifty-one consecutive patients with the last chest symptom within 2 weeks (4 +/- 3 days) were studied echocardiographically. Regional fractional area change during the first 30% of LV filling time in percentage of the segmental end-diastolic area change (CK diastolic index) was used to identify diastolic endocardial motion asynchrony.

RESULTS

After diagnostic coronary arteriography with spasm provocation, 26 patients were diagnosed with coronary spastic angina (CSA) and the other 25 with chest pain syndrome (CPS). Regional delayed relaxation (CK-diastolic index < or = 50%) or diastolic asynchrony had been observed in at least one region in 25 (96%) patients with CSA, whereas it had been noted in 2 (8%) patients with CPS. In 17 (65%) patients with CSA, it had been detected in multiple vascular territories, suggesting multivessel spasm. The diastolic asynchrony disappeared in CSA after a month of angina-free period.

CONCLUSION

Analysis of CK images allows identification of regional LV delayed relaxation or diastolic asynchrony in patients with coronary vasospasm, differentiating them from patients with chest pain syndrome (sensitivity 96%, specificity 92%).

Diastolic filling abnormalities by color kinesis in newborns exposed to intrauterine cocaine

Because cocaine crosses the placenta, we prospectively evaluated global and segmental systolic and diastolic cardiac function by color kinesis in clinically asymptomatic newborns who were exposed to cocaine in utero (group 1, n = 82). Their data were compared with normal controls (group 3, n = 87) and newborns exposed to drugs other than cocaine (group 2, n = 108). During left ventricular filling, newborns exposed to cocaine, compared with groups 2 and 3, had significantly (P <.05) higher global fractional area change (%) (76 +/- 10.3 vs 72 +/- 9.4 and 72 +/- 9.1, respectively), regional fractional area changes (%) for the anterior, septal, inferior, and lateral wall, and in the index of asynchrony (at 50% filling 13.2 +/- 5.8 vs 11.3 +/- 4.1 and 11.6 +/- 4.2, respectively). There were no significant differences in systolic function among the 3 groups. Prenatal cocaine exposure in asymptomatic infants leads to higher global and segmental fractional area changes and asynchrony during diastole. The significance and course of these alterations require further investigation.

Assessment of normal and ischaemic myocardium by quantitative M-mode tissue Doppler imaging

This paper presents a methodology and a software package developed to quantify M-mode tissue Doppler imaging (TDI), defining a number of quantitative parameters drawn from velocity and gradient curves obtained after segmenting the myocardial wall into anatomical layers. The independent clinical predictive value of these parameters to detect motion abnormalities in the presence of ischaemia was evaluated in a comparative study between a group of 17 healthy volunteers and 18 ischaemic patients. Factor analysis and stepwise logistic regression were used to assess the independent predictive value of these parameters in detecting abnormal contractility of the basal posterior segment. The statistical analysis performed has proved that any single parameter related to the gradient intensity, particularly the maximum gradient at the moment of the "e" wave, provides meaningful clinical information, achieving a rate of correct classification of 79.1% on the same data set used for the analysis. Adding additional parameters does not improve the diagnostic performance. Further testing with different settings (stress studies, other pathologies or segments) is warranted.

Phase contrast MRI of myocardial 3D strain by encoding contiguous slices in a single shot

Quantitative measurements of inherently three-dimensional (3D) cardiac strain and strain rate require 3D data; MRI provides uniquely high sensitivity to material strain by combining phase contrast with single-shot acquisition methods, such as echo-planar imaging (EPI). Previous MRI methods applied to 3D strain used multiple two-dimensional (2D) acquisitions and suffered loss of sensitivity due to magnification within the strain calculation of physiologic noise related to cardiac beat-to-beat variability. In the present work, each single-shot acquisition generates 3D image data by acquiring two contiguous 2D Fourier transform (FT) images in a single echo train of an EPI readout. Although strain encoding divides across multiple EPI shots, each strain component is computed only within single-shot data, avoiding noise magnification. Strain tensor maps are displayed using iconic 3D graphics or a simple color code of tensor shape. In a deforming gel phantom, gradient-recalled echo (GRE) MRI movies of 3D strain rates match expected strain fields. In normal human subjects, 3D strain rate tensor movies of heart and brain comprising seven slices in each of seven cardiac phases were completed in 56 heartbeats. Stimulated echo (STE) MRI of net systolic 3D strain was also demonstrated. Two-slices-in-one-shot spatial encoding permits a complete quantitative survey of ventricular 3D strain in under a minute, with routine patient supervision and turnkey image processing.

Age-dependent changes in regional diastolic function evaluated by color Doppler myocardial imaging: a comparison with pulsed Doppler indexes of global function

The goals of this study were to evaluate possible normal age-related changes in regional myocardial relaxation as detected by color Doppler myocardial imaging (CDMI) velocities and to compare the extent of any such changes with age-induced changes in global diastolic function. In 80 healthy subjects (aged 21 to 72 years, equally subdivided by decades) the mitral flow velocities in early diastole (E) and atrial contraction (A) were recorded as were the velocities of left ventricular (LV) motion of early (EDV) and late diastole (LDV) in the 16 standard LV segments, and their ratios were calculated. In healthy persons younger than 40 years, all segments showed an EDV/LDV ratio > 1, whereas in healthy persons aged 40 years or older the mean EDV of all segments decreased, and the mean LDV increased, resulting in a significant decrease of the mean EDV/LDV ratio with age. Values of EDV/LDV ratios were higher than E/A ratios (P <.0001), but their changes with age correlated well with each other (r = 0.805). With increasing age, an EDV/LDV ratio <1 was observed more often in basal segments (P <.001, compared with mid and apical segments) and less often in segments of anteroseptal and posterior walls viewed from the parasternal window. The presence of >50% segments with an EDV/LDV ratio <1 was associated with an E/A ratio <1. Regional diastolic function indexes as evaluated by CDMI changed with increasing age in a heterogeneous way and influenced global diastolic function parameters.

Real-time strain rate echocardiographic imaging: temporal and spatial analysis of postsystolic compression in acutely ischemic myocardium

Postsystolic compression (PSC) is a sensitive indicator of regional left ventricular ischemic diastolic dysfunction. Quantitative assessment of compression patterns by strain rate imaging could determine the presence and spatial extent of PSC for the detection and analysis of acute ischemic diastolic dysfunction. With the use of a segmental left ventricular model, we evaluated time to compression/expansion crossover (T-CEC) in standard apical views. Data at baseline and after acute left anterior descending coronary artery occlusion were collected from 18 open-chest pigs. We found significant mean prolongation of T-CEC, ranging from 43.9 +/- 48.6 ms to 110.8 +/- 73.8 ms, in all apical segments and in 2 midventricular (anterior and anteroseptal) segments. Analysis of variance demonstrated that the prolonged T-CEC is spatially consistent with perfusion defect. The temporal and spatial analysis of T-CEC with the use of strain rate imaging is a new noninvasive technique for identification and topographic quantitation of ischemic diastolic dysfunction expressed by PSC.

Detection of regional temporal abnormalities in left ventricular function during acute myocardial ischemia

Echocardiographic diagnosis of myocardial ischemia is based on visualizing hypokinesis, which occurs late in the ischemic cascade. We hypothesized that temporal changes in endocardial motion may constitute sensitive early markers of ischemia. Two protocols were performed in 19 anesthetized pigs. Protocol 1 included 54 intracoronary balloon occlusions. Transthoracic images were acquired at baseline and every 15 s during 5 min of occlusion and reperfusion. In protocol 2, ischemia was induced in 12 animals by use of graded dobutamine infusion, after creating significant partial occlusions without a resting wall motion abnormality. Systolic and diastolic endocardial motion was color encoded using color kinesis and analyzed using custom software. All ischemic episodes caused detectable and reversible changes. The earliest sign of ischemia was tardokinesis in 31/54 occlusions, whereas hypokinesis appeared first in 23/54 cases. Dobutamine-induced ischemia caused tardokinesis first in 9/12 and hypokinesis in 3/12 animals. Reversible ischemic changes in regional left ventricular performance can be objectively detected using analysis of echocardiographic images and will likely improve the early noninvasive diagnosis of acute ischemia.

Regional asynchrony during acute myocardial ischemia quantified by ultrasound strain rate imaging

OBJECTIVES

We propose a new method to easily quantify asynchronous wall motion due to postsystolic shortening (PSS). We also studied the relationship of the spatial and temporal extent of PSS to the extent of myocardium at ischemic risk after variable duration of ischemia.

BACKGROUND

Postsystolic shortening is a sensitive marker of asynchrony during ischemia. Current techniques for detection of asynchrony are either subjective, or invasive and time-consuming. Strain rate imaging (SRI) can noninvasively depict PSS as prolonged compression/expansion crossover.

METHODS

Nineteen open-chest pigs were scanned from apical views, before and after left anterior descending coronary artery occlusion. Strain rates were derived offline from tissue Doppler velocity cineloops. The time from electrocardiographic R-wave to the occurrence of compression/expansion crossover (TCEC) was calculated. Prolonged TCEC during ischemia was identified using a standardized analysis and both spatial (% of left ventricle) and temporal extent were quantified. The extent of myocardium at risk was measured in seven animals from dye-stained specimens.

RESULTS

Prolonged TCEC was found in all ischemic segments. There was a good correlation (r = 0.91; p < 0.001) and good agreement between the spatial distributions of prolonged TCEC and myocardium at risk. The extent of myocardium at risk was better approximated by TCEC measurement (36 +/- 7% vs. 39 +/- 8%, respectively; p = NS) than by wall motion analysis (47 +/- 17%, p < 0.05). The duration of occlusion did not prolong TCEC.

CONCLUSIONS

Prolonged TCEC consistently occurs in ischemic myocardium and is apparently not affected by the duration of ischemia. Standardized analysis of TCEC in SRI closely quantifies the extent of ischemic myocardium. This new method may be a useful tool in other cardiac conditions associated with regional diastolic asynchrony.

Normal values of regional left ventricular endocardial motion: multicenter color kinesis study

Our goal was to establish normal values for quantitative color kinesis indexes of left ventricular (LV) wall motion over a wide range of ages, which are required for objective diagnosis of regional systolic and diastolic dysfunction. Color-encoded images were obtained in 194 normal subjects (95 males, 99 females, age 2 mo to 79 yr) in four standard views. Quantitative indexes of magnitude and timing of systolic and diastolic function were studied for age- and gender-related differences. Normal limits of all ejection and filling indexes were in a narrow range (< or =25% of the mean), with no major gender-related differences. Despite invariable ejection fractions, both peak filling and ejection rates decreased with age (30 and 20%, correspondingly) with a concomitant increase in mean filling and ejection times, resulting in five- and twofold increases in the late to early filling and ejection ratios, correspondingly. Diastolic asynchrony increased with age (from 4.7 +/- 2.0 to 6.4 +/- 3.2 from the 2nd to 7th decade). The normal values of color kinesis indexes should allow objective detection of regional LV systolic and diastolic dysfunction.

Regional diastolic function by pulsed Doppler myocardial mapping for the detection of left ventricular ischemia during pharmacologic stress testing: a comparison with stress echocardiography and perfusion scintigraphy

OBJECTIVES

We evaluated regional diastolic function by pulsed Doppler myocardial mapping for the detection of left ventricular ischemia during pharmacologic stress testing.

BACKGROUND

Evaluation and quantification of diastolic myocardial function remain a challenge for imaging techniques in stress tests.

METHODS

A prospective study compared the detection of coronary artery stenosis: 1) by pulsed Doppler myocardial mapping, 2) by two-dimensional echocardiographic dobutamine stress test, and 3) by perfusion scintigraphy in 64 patients using coronary angiography for reference. An age matched subgroup of 10 patients with normal angiograms and two-dimensional echocardiographic stress test served as control group. Peak myocardial contraction velocity (Vc) and lengthening rate during early diastolic left ventricular (LV) filling (VE) were measured in 12 LV segments from three apical views.

RESULTS

In controls, myocardial velocities increased during stress by > or =3.6 cm/s (p < 0.001). In LV segments depending on a stenosed artery (n = 70), VE decreased by > or =1 cm/s and, thus, was different from control segments (n = 112, p < 0.001) and from scar segments (n = 13, p < 0.01), whereas the change of Vc was similar to that in scar segments. A stress induced 2 cm/s reduction of VE discerned the best diagnostic accuracy (sensitivity 84%, specificity 93%) in comparison with two-dimensional echocardiography (78% and 71%) and perfusion scintigraphy (61% and 86%). Using receiver operating curves at incremental levels of luminal narrowing, these relations persisted.

CONCLUSIONS

Quantification of diastolic myocardial function by pulsed Doppler myocardial mapping during dobutamine stress test was shown to be a feasible, accurate, reproducible, noninvasive technique that should be considered to be a sensitive alternative to the present echocardiographic and scintigraphic imaging techniques for stress tests.

High-frame-rate tissue harmonic imaging enhances anatomic M-mode sections of the left ventricle in short-axis view

BACKGROUND

High-frame-rate echocardiography (HFRE) and tissue harmonic imaging (THI) may improve image quality, thereby enabling anatomic M-mode sections of left ventricular (LV) wall segments to be visualized in various planes in the short-axis view.

OBJECTIVES

The goals of this study were to compare image quality between HFRE and conventional-frame-rate echocardiography (CFRE) and between fundamental imaging (FI) and THI, and to obtain anatomic M-mode values of basal short-axis LV segments from healthy subjects for use in the evaluation of abnormal segments in patients with myocardial infarction (MI).

METHODS AND RESULTS

The study included 28 healthy subjects and 15 patients with MI who underwent 2-dimensional echocardiography with an ultrasonographic system equipped with THI and anatomic M-mode. Left ventricular image cineloops at the basal short-axis view that were obtained with 3 combinations of imaging techniques (FI + CFRE, FI + HFRE, and THI + HFRE) were digitized and displayed side-by-side in random order for comparison by blinded readers. M-mode sections were done in 3 planes: anteroseptal-posterior, inferoseptal-lateral, and anterior-inferior basal segments. The THI + HFRE combination showed the best image quality with significant reduction in noise artifacts, resulting in a good signal-to-noise ratio and good tractability of all LV segments by anatomic M-mode. In healthy subjects, significant intersegmental differences existed in the diastolic and systolic thicknesses and in the percent systolic thickening of LV segments. In patients with MI, LV systolic thickening was significantly decreased in abnormal segments. No significant differences were noted in ejection fraction and fractional shortening among the 3 anatomic M-mode planes.

CONCLUSION

High-frame-rate tissue harmonic imaging improved image quality, thereby allowing reproducible anatomic M-mode measurements in various planes in the short-axis view and providing a convenient objective evaluation of global and regional LV function.

Tissue Doppler imaging (TDI) for on-line detection of regional early diastolic ventricular asynchrony in patients with coronary artery disease

Diastolic filling of the left ventricle is often impaired in patients with coronary artery disease (CAD) in the absence of systolic wall motion abnormalities or previous myocardial infarction. The current study was designed to assess the ability of tissue Doppler imaging (TDI) for on-line detection of regional diastolic wall motion abnormalities to identify CAD in patients with preserved systolic function. 20 normal subjects (age 51 +/- 13 years) and 17 CAD patients with normal systolic function and > or = 70% luminal narrowing of the LAD (age 56 +/- 11 years) were included. Coronary anatomy was unknown to the echocardiographer. In the parasternal short axis and the apical 4-chamber-view, peak tissue velocities of the anterior/inferior and the midseptal/midlateral LV segments during rapid ejection (RE), isovolumic relaxation (IR), rapid filling (RF) and atrial contraction (AC) were analyzed by color-M-Mode-TDI. In the apical view, in 13 of 35 (37%) patients with adequate recordings, myocardial asynchrony was detected during IR: while the septum was moving inwards (red color-coding), the lateral wall was moving outwards (blue/green coding). In the remaining 22 patients (63%) a slow, synchronous outward motion of septum and lateral wall with homogeneous color-coding (blue/green) was seen. Unblinding of the coronary status revealed a critical LAD stenosis in all 13 patients (100%) with myocardial asynchrony. Analysis of midseptal peak velocities during IR revealed positive velocities (1.22 +/- 1.64 cm/s) in CAD patients and negative velocities (-1.39 +/- 0.81 cm/s) in normal subjects. Thus, TDI allowed for the on-line detection of early diastolic asynchrony in 13 of 16 (82%) patients with critical LAD-narrowing. Due to the rapid assessment of regional wall motion abnormalities, TDI might help to identify CAD in patients with normal systolic function.

A comparison of the interpretation of digitized and videotape recorded echocardiograms

Conventional echocardiograms are typically recorded on videotape and later reviewed and interpreted by a physician. Although videotape recording is an excellent medium for this purpose, it does have several disadvantages, which may be overcome by digital storage. This study compared the diagnostic accuracy of digitized and videotape recorded echocardiograms. Echocardiographic examinations (n = 110) were recorded simulta-neously on videotape and were digitized with a commercially available frame grabber system. Images were transmitted by an Ethernet link to the network-based computer system and compressed with a nondestructive compression algorithm. Images were reviewed on a personal computer. Images were interpreted by 3 observers, and differences in interpretation were documented. There were 274 findings in 110 patients. Exact agreement in interpretation was found in 83%. A major discrepancy occurred in 2%, and a minor discrepancy occurred in 15%. Most discrepancies occurred in the setting of valvular heart disease. When compared with a consensus interpretation, no significant difference was seen in the number of errors between the digital and videotape interpretation. We conclude that the interpretation of a properly recorded digitized echocardiographic examination yields interpretations equivalent to those of videotape recordings.

Regional Left Ventricular Diastolic Dysfunction Evaluated by Pulsed-Tissue Doppler Echocardiography

Pulsed-wave Doppler tissue imaging (DTI) allows the examination of regional wall motion at a very high temporal resolution and therefore constitutes an excellent technique for assessing diastolic motion of left ventricular walls. Regional relaxation has been well characterized in normal subjects using this technique, and physiological time intervals and motion wave profiles are described. In an experimental model of acute ischemia, local relaxation impairment was observed showing highly characteristic local diastolic abnormalities. Interestingly, these findings took place before any decrease in systolic motion was recordable. In a prospective clinical study, noninvasive regional DTI parameters were compared with coronary angiography to assess the feasibility and clinical value of the technique; the diagnostic accuracy is discussed in detail. Also, the association between regional diastolic parameters and global regional function as assessed by Doppler analysis of transmitral left ventricular filling flow was studied, stressing the impact of regional diastolic function on overall ventricular performance. Finally, the diagnostic role of pulsed-wave DTI on stress testing, identification of myocardial viability, and microvascular angina is reviewed.

Regional Diastolic Function in Microvascular Angina Studied by Pulsed-Wave Doppler Tissue Imaging

OBJECTIVES: Diastolic dysfunction is an early finding during myocardial ischemia. However, regional diastolic function has not been studied in patients with microvascular angina (MA). The purpose of this study was to assess the regional diastolic function in patients with MA through use of the new echocardiographic technique, pulsed-wave Doppler tissue imaging (DTI). METHODS: Regional diastolic function was studied by DTI in 81 myocardial segments of seven patients with MA and in 54 segments of six healthy control subjects. RESULTS: Myocardial segments in patients with MA had, in comparison with controls, an increased regional isovolumetric relaxation time (126 +/- 34 vs 99 +/- 34 msec, P < 0.0001), a higher e/a ratio (1.1 +/- 0.7 vs 0.8 +/- 0.3, P = 0.0048), and a lower peak velocity of the late diastolic wave a (6.9 +/- 2.9 vs 8.4 +/- 1.7 cm/msec, P = 0.0009). Moreover, peak velocity of systolic wave s was higher in patients with MA (5.8 +/- 1.4 vs 5.3 +/- 1.2 cm/msec, P = 0.0424). CONCLUSIONS: Patients with MA have an impaired regional diastolic function (an increased regional isovolumetric relaxation time and a lower a wave) and a higher velocity of the regional systolic wave s. These findings may have physiopathological implications.

Assessment of left ventricular dyssynergy by color kinesis

Color kinesis is a new echocardiographic technique based on acoustic quantification. It has been developed to facilitate the ability to identify contraction abnormalities and has been incorporated into a commercially available ultrasound imaging system. The potential of this technique to improve the qualitative and quantitative assessment of wall motion abnormalities is described. Evaluation of color-encoded images allows detection of decreased amplitude of endocardial motion in abnormally contracting segments as well as a shorter time of endocardial excursion in segments with severely decreased motion. Compared with off-line quantitative studies, color kinesis has the advantage to be used on-line, without time-consuming manual tracing of endocardial boundaries. In addition, a single end-systolic color image contains the entire picture of spatial and temporal contraction and can be digitally stored and retrieved. In patients with proven coronary artery disease, color kinesis had a sensitivity of 88%, a specificity of 77%, and an overall accuracy of 86% in identifying the presence of segmental dysfunction. The practical application of color kinesis might be to improve our ability to distinguish normal from hypokinesis, something that has always been difficult in clinical echocardiography. Segmental analysis of color kinesis images allows objective detection of dobutamine-induced regional wall motion abnormalities in agreement with conventional visual interpretation of the corresponding 2-dimensional views. A method for objective assessment of wall dynamics during dobutamine stress echocardiography would be of particular clinical value, because these images are even more difficult to interpret than conventional echocardiograms. Quantitative assessment of diastolic function may allow objective evaluation of segmental relaxation abnormalities, especially under conditions of pharmacologic stress testing. Acquisition of color kinesis images during dobutamine stress echocardiography, both transthoracic and transesophageal, may facilitate the assessment of hybernating but viable myocardium and enhance the sensitivity in the detection of coronary artery disease.

Use of color kinesis for evaluation of left ventricular filling in patients with dilated cardiomyopathy and mitral regurgitation

OBJECTIVES

We tested the feasibility of using analysis of color kinesis images to objectively assess global and regional left ventricular (LV) diastolic function in patients with dilated cardiomyopathy (DCM). In addition, the ability of this technique to track drug-induced changes on LV diastolic properties was studied.

BACKGROUND

Diastolic dysfunction contributes to symptomatology in patients with DCM. The assessment of LV diastolic function using conventional Doppler echocardiography is indirect and is confounded by multiple variables. Moreover, the noninvasive evaluation of regional diastolic properties is difficult. In contrast, color kinesis directly tracks and color-encodes regional diastolic endocardial motion.

METHODS

We studied 24 patients with DCM and mitral regurgitation (MR) and 24 age-matched normal subjects. Transmitral and pulmonary vein flow velocities were measured using pulsed Doppler echocardiography. Diastolic color kinesis images were used to calculate indexes of magnitude and timing of global and regional diastolic function. Diastolic asynchrony was evaluated in different subgroups of patients with DCM. The effects of drug infusions (nitroprusside and dobutamine) were also studied.

RESULTS

Color kinesis indexes of global diastolic function showed significant differences between patients with DCM and normal subjects. Compared with Doppler indexes, color kinesis was less confounded by MR and was capable of differentiating between drug-induced lusitropic and vasodilator effects. Diastolic asynchrony was increased in patients with DCM and severe MR.

CONCLUSIONS

Quantitative analysis of global and regional LV diastolic function in patients with DCM using color kinesis is feasible.

The Sensitivity of Exercise Echocardiography Can Be Improved by Taking the Delayed Myocardial Contraction into Account

The purpose of this study was to test whether the systolic myocardial wall motion abnormalities at the early stages of ischemia are applicable to the diagnosis of coronary artery disease. Forty-four patients with suspected coronary artery disease were studied with the use of low-level exercise echocardiography. Exercise was stopped at the onset of first cardiac symptoms, and no patient exceeded 70% of the age-predicted maximal heart rate level. Forty patients had significant stenosis in at least one coronary artery on coronary angiography. Ten control subjects with a low probability of ischemic heart disease also were studied with exercise echocardiography. The first ischemic wall motion abnormality in systole, defined as delayed onset of the contraction (a regional delay of at least 100 milliseconds in a frame-by-frame analysis of echocardiograms) without any reduction in systolic movement, was regarded separately from hypokinesis (systolic wall motion excursion of less than 5 mm). When the delayed onset of the contraction also was taken into account, 37 of the 40 patients with coronary artery disease had an ischemic response after exercise. The sensitivity of the test thus was 93%. The reduction in systolic wall movement was detected in only 18 of these patients at the exercise level attained (70% or less of age-predicted maximal heart rate). There were two false-positive echocardiograms, but when the control group also was considered, the specificity of the test remained high at 86%. The sensitivity of exercise echocardiography can be increased by paying attention to the delayed onset of the systolic contraction, which occurs at the early stages of ischemia.

Segmentation and tracking in echocardiographic sequences: active contours guided by optical flow estimates

This paper presents a method for segmentation and tracking of cardiac structures in ultrasound image sequences. The developed algorithm is based on the active contour framework. This approach requires initial placement of the contour close to the desired position in the image, usually an object outline. Best contour shape and position are then calculated, assuming that at this configuration a global energy function, associated with a contour, attains its minimum. Active contours can be used for tracking by selecting a solution from a previous frame as an initial position in a present frame. Such an approach, however, fails for large displacements of the object of interest. This paper presents a technique that incorporates the information on pixel velocities (optical flow) into the estimate of initial contour to enable tracking of fast-moving objects. The algorithm was tested on several ultrasound image sequences, each covering one complete cardiac cycle. The contour successfully tracked boundaries of mitral valve leaflets, aortic root and endocardial borders of the left ventricle. The algorithm-generated outlines were compared against manual tracings by expert physicians. The automated method resulted in contours that were within the boundaries of intraobserver variability.

How does computer-assisted digital wall motion analysis influence observer agreement and diagnostic accuracy during stress echocardiography?

This study assessed interobserver and intraobserver variation and diagnostic accuracy during 25 dipyridamole stress echocardiography tests interpreted with different analysis systems: a) computer display of high frame rate digital cineloops (47 frames/s); b) computer display of lower frame rate digital cineloops (24 frames/s); and c) videotape recordings. The majority of the patients (84%) had documented coronary artery disease with baseline wall motion abnormalities due to previous myocardial infarctions and/or coronary bypass surgery, thus comprising a population with difficult interpretation of stress echocardiography. Diagnostic accuracy was assessed using coronary angiography as reference method. Interobserver and intraobserver agreement was highest when analysis was performed from computer-displayed cineloops, 96 and 92%, respectively, compared to 84 and 80% respectively, using videotape recordings. Sensitivity for identification of coronary artery stenosis was similar using digital cineloops with high frame rate or videotape recordings (67% to 80% for both systems), and tended to be lower using cineloops with lower frame rate for analysis (53%). Inter- and intraobserver differences for wall motion score index were not significantly influenced by the analysis system. We conclude that computer assisted analysis with high frame rate of the displayed cineloops provides optimal observer agreement and diagnostic accuracy in the same range as videotape analysis in patients undergoing stress echocardiography.

On-line quantitative assessment of left ventricular filling during dobutamine stress echocardiography: a useful addition to conventional wall motion scoring

In order to determine whether the diastolic rate of ventricular volume change obtained on-line with an automatic border detection (ABD) system during dobutamine stress echocardiography (DSE) would provide an interpretation of the diastolic ventricular response to the drug in quantitative terms in the assessment of coronary artery disease, we studied, with ABD and DSE, 59 patients who underwent coronary arteriography within 2 months of the stress test. Eleven patients had normal coronary findings or non-significant coronary lesions. Significant (> or =70% diameter stenosis) coronary artery disease (CAD) was present in 48 patients (81%). Dobutamine stress echocardiography (DSE) to a maximal dose of 50 microg/kg per min was performed in all patients. ABD images were acquired at rest and at the peak of infusion along with conventional two-dimensional images. The following measurements were evaluated: left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular ejection fraction (LVEF), slope of rapid filling segment (RFS), peak filling rate (PFR), rapid filling phase fractional change (RFFC). Patients with non-significant coronary artery lesions exhibited a hyperdynamic response with an LVEF increment of at least 20% from baseline to peak drug infusion. In these patients the effect of dobutamine produced an increase of RFS from 35.5+/-5.6 to 86.5+/-10.5 ml/s, an increase of PFR from 4.4+/-0.6 to 6.8+/-0.6 EDV/s, and an increase of RFFC from 74+/-8 to 92+/-5% (P<0.001). Of the 48 patients with coronary artery disease, 27 had <20% LVEF increase at peak dobutamine infusion. Four of 22 patients with single vessel disease and 23 of 26 patients with multivessel disease had an abnormal systolic response. After dobutamine infusion single vessel CAD patients showed a decrease of RFS from 33.4+/-5.3 to 26.7+/-5.9 ml/s, a decrease of PFR from 3.8+/-0.7 to 3.0+/-0.7 EDV/s, and a decrease of RFFC from 73+/-6 to 59+/-4% (P<0.001). Multivessel CAD patients showed a decrease of RFS from 32.0+/-5.9 to 23.1+/-4.1 ml/s, a decrease of PFR form 3.8+/-0.6 to 2.8+/-0.6 EDV/s, and a decrease of RFFC from 71+/-5 to 54+/-8% (P<0.001). The overall sensitivity of detecting CAD was 85% for conventional DSE and 90% for ABD-DSE (P=NS). The sensitivities of detecting patients with single vessel and multivessel CAD with conventional DSE were 68 and 92%, respectively, and with ABD-DSE were 91% (P<0.01) and 96% (P=NS), respectively. Our results show that an abnormal diastolic as well as systolic response during on-line quantitative assessment of dobutamine stress echocardiography is a sensitive marker of coronary artery disease and is predictive for the detection of extensive lesions. The described measurements can be utilized to improve the DSE sensitivity in identifying coronary artery disease. On-line quantitation of diastolic indexes with ABD can represent another step toward obtaining uniform results after stress echocardiography.