Usefulness of myocardial velocity gradient derived from two-dimensional tissue Doppler imaging as an indicator of regional myocardial contraction independent of translational motion assessed in atrial septal defect

Ultrasound imaging for assessing functions of the GI tract

OBJECTIVE

In the following review we outline how ultrasound can be used to measure physiological processes in the gastrointestinal tract.

APPROACH

We have investigated the potential of ultrasound in assessing gastrointestinal physiology including original research regarding both basic methodology and clinical applications.

MAIN RESULTS

Our main findings show the use of ultrasound to study esophageal motility, measure volume and contractility of the stomach, assess motility, wall thickness, and perfusion of the small bowel, and evaluate wall vascularization and diameters of the large bowel.

SIGNIFICANCE

Ultrasound is a widely accessible technology that can be used for both scientific and clinical purposes. Being radiation-free and user friendly, the examination can be frequently repeated enabling longitudinal studies. Furthermore, it does not influence normal GI physiology, thus being useful to estimate motility and subtle changes in physiology. Accordingly, ultrasound scanning and physiological measurements may make a big difference for the scientist and the doctor; and for the patients who receive an efficient work-up.

Systemic sclerosis and the heart

Heart disease, either clinically apparent or silent, is a frequent complication of systemic sclerosis (SSc, scleroderma) and may affect both patients with diffuse cutaneous and limited cutaneous SSc. The availability of more sensitive modalities has led to an increased awareness of scleroderma heart disease, which often involves the pericardium, myocardium, and cardiac conduction system. This awareness of cardiac involvement requires attention and interventions led by internists, cardiologists, and rheumatologists. Although no specific therapy exists for scleroderma heart disease, early recognition of the presence and type of scleroderma heart disease may lead to more effective management of patients with scleroderma.

Primary myocardial involvement in systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized by diffuse vascular lesions and fibrosis. Primary myocardial involvement is common in SSc and, when clinically evident, appears as a poor prognostic factor. An increasing body of evidence suggests that myocardial involvement is due, at least in part, to microcirculation impairment with abnormal vasoreactivity, with or without associated structural abnormalities of the small coronary arteries or arterioles. Using conventional methods, myocardial perfusion impairment, systolic and diastolic left ventricular dysfunction and right ventricular dysfunction have been reported in SSc. Recently, tissue Doppler echocardiography and magnetic resonance imaging have confirmed these results. Vasodilators, such as calcium channel blockers and angiotensin converting enzyme inhibitors, improve both myocardial perfusion and function abnormalities.

Detection of myocardial dysfunction in the presence of normal ejection fraction

Detection of subclinical myocardial involvement is of utmost importance in risk stratification and prognosis; the role of ejection fraction in the detection of subclinical disease may be unhelpful. Our aim was to evaluate the methodology and importance of early detection of myocardial involvement in the presence of normal ejection fraction. Most of the pertinent English and non-English articles published from 1980 to 2006 in Medline, Scopus, and EBSCO Host research databases have been reviewed. Serial assessment of systolic function with different techniques should be avoided, since imaging modalities and ejection fraction measurements are not interchangeable. Additional non-invasive tools still are needed for the identification of subclinical left ventricular dysfunction in certain diseases. The recognition of subclinical involvement will prompt initiation of specific therapy to prevent the development of overt left ventricular dysfunction. This also is needed for determining the best timing for intervention in asymptomatic patients with metabolic and valvular disorders.

Advanced imaging and visualization in gastrointestinal disorders

Advanced medical imaging and visualization has a strong impact on research and clinical decision making in gastroenterology. The aim of this paper is to show how imaging and visualization can disclose structural and functional abnormalities of the gastrointestinal (GI) tract. Imaging methods such as ultrasonography, magnetic resonance imaging (MRI), endoscopy, endosonography, and elastography will be outlined and visualization with Virtual Reality and haptic methods. Ultrasonography is a versatile method that can be used to evaluate antral contractility, gastric emptying, transpyloric flow, gastric configuration, intragastric distribution of meals, gastric accommodation and strain measurement of the gastric wall. Advanced methods for endoscopic ultrasound, three-dimensional (3D) ultrasound, and tissue Doppler (Strain Rate Imaging) provide detailed information of the GI tract. Food hypersensitivity reactions including gastrointestinal reactions due to food allergy can be visualized by ultrasonography and MRI. Development of multi-parametric and multi-modal imaging may increase diagnostic benefits and facilitate fusion of diagnostic and therapeutic imaging in the future.

Ultrasound imaging versus morphopathology in cardiovascular diseases: the heart failure

This review article summarizes the results of histopathological studies to assess heart failure in humans. Different histopathological features underlying the clinical manifestations of heart failure are reviewed. In addition, the present role of echocardiographic techniques in assessing the failing heart is briefly summarized.

Reduced myocardial contractility assessed by tissue Doppler echocardiography is associated with increased risk during adrenal surgery of patients with pheochromocytoma: report of a preliminary study

BACKGROUND

Depressed myocardial contractility, although rarely reported in pheochromocytoma, might be underestimated. It may be a determinant of perioperative risk during adrenal surgery.

METHODS

We prospectively studied consecutive patients with pheochromocytoma; myocardial function examined by standard and tissue Doppler echocardiography was compared with matched control subjects. The incidence of hemodynamic collapse during adrenal surgery was measured.

RESULTS

A total of 15 patients were included (8 men, 46 [17] years, hypertension in 10). All but one had a normal left ventricular ejection fraction. However, compared with control subjects, they had a depressed systolic strain rate (SR) (1.8 [2.1] vs 4.1 [2.2] s(-1), P = .007). Furthermore, 6 of 8 patients with systolic SR less than 2 s(-1) experienced intraoperative collapse, versus 1 of 7 with SR greater than 2 s(-1) (P = .041). No association was observed with other variables.

CONCLUSIONS

Patients with pheochromocytoma may have depressed myocardial contractility detected by tissue Doppler echocardiography despite a normal standard echocardiogram. A systolic SR less than 2 s(-1) was associated with an increased risk of perioperative collapse.

Prediction of subclinical left ventricular dysfunction with strain rate imaging in patients with mild to moderate rheumatic mitral stenosis

BACKGROUND

Left ventricular (LV) long-axis function evaluated by Doppler tissue echocardiography-derived strain rate (SR) imaging has been shown to be a useful index of LV systolic function; however, it has not been evaluated in patients with mitral stenosis (MS). We examined the LV long-axis function of patients with pure MS and normal global systolic function as assessed by LV ejection fraction.

METHOD

In all, 30 patients (22 women; 45 +/- 9 years) with mild to moderate MS (mitral valve area = 1.5 +/- 0.3 cm2) and 28 healthy volunteers (20 women; 44 +/- 10 years) were evaluated by both conventional and Doppler tissue echocardiography. Two-dimensional Doppler tissue echocardiography was performed in the apical 4-chamber view in the septal and lateral wall on the mitral annular level. Peak systolic myocardial SR and end-systolic strain data were measured for both segments.

RESULTS

Peak systolic SR (1.2 +/- 0.4% vs 1.8 +/- 0.39%, P < .001) and end-systolic strain (10 +/- 5 vs 25 +/- 6 s(-1), P < .001) were both significantly lower in patients with MS than in control subjects.

CONCLUSIONS

Patients with MS had significantly impaired long-axis function evaluated by Doppler tissue echocardiography-derived SR imaging despite normal global systolic function.

New aspects of the ventricular septum and its function: an echocardiographic study

OBJECTIVES

To examine whether the line dividing the septum into two layers is found consistently by conventional echocardiography and to evaluate functional differences in the right and left side of the septum in terms of wall thickening, strain rate, and strain imaging.

DESIGN

In a systematic study in 30 normal subjects, M mode and Doppler myocardial imaging data from the interventricular septum (IVS) were recorded. Velocity curves, regional strain rate, and strain profiles were obtained. Systolic deformation (wall thickening, radial and longitudinal strain rate, and strain) of both sides were assessed. Furthermore, three patients with one sided abnormalities were studied.

RESULTS

A bright echo consistently segmented the IVS into a left and right part. In this normal population radial deformation was different for the left and right side of the septum (mean (SD) wall thickening on the left, 49 (46)%, and on the right, 17 (38)%; strain rate on the left, 3.8 (0.6) 1/s, and on the right, 2.1 (1.9) 1/s; strain on the left, 41 (17)%, and on the right, 22 (14)%), whereas longitudinal deformation was found to be similar (strain rate on the left, -2.2 (0.7) 1/s, and on the right, -2.0 (0.6) 1/s; strain on the left, -28 (12)%, and on the right, -25 (12)%). The presented clinical examples show that abnormalities can be strictly limited to one layer.

CONCLUSIONS

Differential radial deformation and knowledge of fibre architecture showing an abrupt change in the middle of the septum, together with the clinical cases, suggest the septum to be a morphologically and functionally bilayered structure potentially supplied by different coronary arteries.

Evaluation of the effect of nifedipine upon myocardial perfusion and contractility using cardiac magnetic resonance imaging and tissue Doppler echocardiography in systemic sclerosis

BACKGROUND

Primary myocardial involvement due to microcirculation impairment is common in systemic sclerosis (SSc). Cardiovascular magnetic resonance imaging (MRI) and tissue Doppler echocardiography (TDE) were recently shown to be more sensitive than conventional methods for the respective assessment of myocardial perfusion and contractility. Previous studies have suggested that dihydropyridine-type calcium channel blockers mitigate both myocardial perfusion and function abnormalities.

OBJECTIVE

To investigate the effects of nifedipine on myocardial perfusion by MRI and on contractility by TDE, in patients with SSc.

PATIENTS AND METHODS

18 patients with SSc without clinical heart failure and with normal pulmonary arterial pressure (14 women, 4 men; mean (SD) age 59 (9) years; mean (SD) disease duration 7 (4) years, 10 with diffuse and 8 with limited cutaneous forms) were prospectively evaluated. The MRI perfusion index, determined from time-intensity curves, and systolic and diastolic strain rate determined by TDE were assessed at baseline, after a 72 hour vasodilator washout period, and after 14 days of oral treatment with nifedipine 60 mg/day.

RESULTS

Nifedipine treatment led to a significant increase in the MRI perfusion index (mean (SD) 0.26 (0.07) v 0.19 (0.05) at baseline, p = 0.0003) and in systolic and diastolic strain rate (2.3 (0.6) v 1.5 (0.4) s(-1) at baseline, p = 0.0002, and 4.2 (1.6) v 3.0 (1.2) at baseline, p = 0.0003, respectively).

CONCLUSION

Fourteen days of treatment with nifedipine simultaneously improves myocardial perfusion and function, as evaluated by highly sensitive and quantitative methods.

A new Doppler tissue ratio to revisit systole: The pre-ejectional isovolumic to ejectional velocity ratio–application to aging

Most diagnostic applications of Doppler tissue echocardiography rely on peak (Pk) velocity (V) values of single variables or myocardial V gradient. Whereas age-related changes in diastolic V are well-known, previous Doppler tissue echocardiography studies of systolic function showed no age effect for pre-ejectional (Ej) isovolumic (PEI) and Ej inward wall motion Pk V. In addition to myocardial V gradient, ratios were calculated between PEI and Ej Pk V, and mean V averaged over systole (PEI/Ej V ratios) at each layer of the posterior wall using M-mode color on two control groups: A (27 +/- 5 years) and B (54 +/- 10 years). The only changes were for PEI/Ej V ratios (mean V endocardial 21 +/- 7% vs 34 +/- 20%, P = .01; mean V epicardial 27 +/- 8% vs 40 +/- 18%, P = .006; Pk epicardial V 21 +/- 10% vs 30 +/- 16%, P = .04 for groups A and B, respectively). Correlation versus age were r = 0.52 and P = .005 (mean V endocardial), r = 0.50 and P = .007 (mean V epicardial), and r = 0.32 and P = .03 (Pk epicardial V). PEI/Ej V ratios and mean V studied in separate layers showed that the new systolic approach had advantages over single variable or Pk V to study age-related changes.

Assessment of papillary muscle function using myocardial velocity gradient derived from tissue Doppler echocardiography

Papillary muscle (PM) function is vital to mitral valve competence. However, quantitative assessment of the function is difficult due to the complexity of the mitral apparatus. We hypothesized that myocardial velocity gradient (MVG) could be applied to assess PM function. We studied MVG-PM in 123 patients with left ventricular dysfunction (ejection fraction <40%) and 123 normal subjects throughout a systolic phase. MVG-PM in normal subjects was significantly higher than in patients with left ventricular dysfunction (3.6/s vs 1.4/s, p <0.001). MVG-PM reached its peak at early systole and correlated well with PM thickening (r = 0.89). MVG-PM in patients with left ventricular dysfunction correlated with the severity of apical tenting of the mitral valve (y = 0.8x - 0.07, r = 0.72). Patients with lower MVG-PM tended to have less severe mitral regurgitation (y = 0.03x + 0.3, r = 0.83). PM contractility can be quantitatively assessed by calculating the MVG derived from tissue Doppler imaging. PM dysfunction, indicated by lower MVG-PM, decreased mitral leaflet tethering, thus paradoxically decreasing mitral regurgitation severity. MVG is a useful tool in determining the role of PM in functional mitral regurgitation.

Potential application of tissue Doppler imaging to assess regional left ventricular diastolic function in patients with hypertrophic cardiomyopathy: comparison with 123I-beta-methyl iodophenyl pentadecanoic acid myocardial scintigraphy

BACKGROUND

Tissue Doppler imaging (TDI) has been utilized to evaluate left ventricular myocardial dysfunction in patients with hypertrophic cardiomyopathy (HCM); however, no clear explanation for the abnormality of TDI variables has been forthcoming.

HYPOTHESIS

Peak negative myocardial velocity gradient (MVG) derived from TDI may correlate with a disorder of fatty acid metabolism in patients with HCM.

METHODS

Tissue Doppler imaging and 123I-beta-methyl iodophenyl pentadecanoic acid (123I-BMIPP) myocardial scintigraphy were performed in 15 patients with asymmetric septal hypertrophy (mean age 47 +/- 18 years) and in 12 healthy controls (mean age 43 +/- 10 years).

RESULTS

In early 123I-BMIPP images, accumulation defects were observed in the ventricular septum in 12 patients and in the posterior wall in 8 patients with HCM. Peak negative MVG in the ventricular septum (1.1 +/- 0.5 vs. 2.8 +/- 0.5, p < 0.0001) and posterior wall (5.2 +/- 1.4 vs. 6.7 +/- 0.8, p < 0.01 ) was significantly lower in the HCM group than in the controls; also, these parameters were significantly lower in patients with than in those without a defect in the region in question. The peak negative MVG in the ventricular septum and posterior wall correlated inversely with the washout rate in all subjects.

CONCLUSIONS

Peak negative MVG according to TDI is related to disorder of fatty acid metabolism in the regional left ventricular myocardium of patients with HCM.

Tissue Doppler, strain, and strain rate echocardiography for the assessment of left and right systolic ventricular function

Tissue Doppler (TDE), strain, and strain rate echocardiography are emerging real time ultrasound techniques that provide a measure of wall motion. They offer an objective means to quantify global and regional left and right ventricular function and to improve the accuracy and reproducibility of conventional echocardiography studies. Radial and longitudinal ventricular function can be assessed by the analysis of myocardial wall velocity and displacement indices, or by the analysis of wall deformation using the rate of deformation of a myocardial segment (strain rate) and its deformation over time (strain). A quick and easy assessment of left ventricular ejection fraction is obtained by mitral annular velocity measurement during a routine study, especially in patients with poor endocardial definition or abnormal septal motion. Strain rate and strain are less affected by passive myocardial motion and tend to be uniform throughout the left ventricle in normal subjects. This paper reviews the underlying principles of TDE, strain, and strain rate echocardiography and discusses currently available quantification tools and clinical applications.

Strain rate acceleration yields a better index for evaluating left ventricular contractile function as compared with tissue velocity acceleration during isovolumic contraction time: an in vivo study

OBJECTIVE

Our study aimed to investigate whether strain rate acceleration (SRA) during isovolumic contraction time (IVCT) could serve as a sensitive indicator of myocardial function.

METHODS

A total of 8 sheep underwent occlusion of left anterior descending coronary artery or diagonal branches and 2 sheep underwent left circumflex coronary artery occlusion to create septal, apical, or basal segment myocardial ischemia 19 to 27 weeks before the study. Baseline, volume-loading, dobutamine, and metoprolol infusion were used to produce 4 hemodynamic stages for each sheep. Doppler tissue imaging was acquired using a 5-MHz probe (GE/VingMed Vivid Five, GE Medical Systems, Milwaukee, Wis) on open-chest animals using the liver as a standoff at the apex. Using software (EchoPac, GE Medical Systems), SRA during IVCT was calculated and compared with tissue velocity acceleration (TVA) during IVCT from areas located in the normal and ischemic zones. Also, invasively monitored left ventricle dP/dt was measured as reference contractile function.

RESULTS

Both TVA and SRA during IVCT showed higher values for normal tissue than for ischemic area (P <.0001). SRA for normal wall segments changed significantly during the 4 stages (P =.01) with corresponding changes on high-fidelity left ventricular pressure catheters (r = 0.92). TVA over normal segments showed no significant change (P =.29) in the 4 hemodynamic stages. Both TVA and SRA of the ischemic segments showed no significant change with pharmacologic maneuvers or loading conditions.

CONCLUSIONS

SRA and TVA during IVCT are both useful indicators for detecting abnormal heart wall motion. However, SRA tends to be more sensitive than TVA for differentiating the response to stress conditions.

Clinical relevancy of the myocardial velocity gradient: limitations of a binary response

BACKGROUND

Doppler tissue echocardiographic myocardial velocity gradient (MVG) overcomes translational or tethered motion effects. Diagnostic applications rely on MVG numeric value, an instantaneous value calculated at peak endocardial velocity. Our aim was to test the clinical relevancy of MVG for patients with dilated cardiomyopathy (CM) at rest. Efficiency of MVG, as a marker of the underlying mechanism, ischemic or nonischemic, was compared with that of mean velocities averaged over a cycle.

METHODS

Peak and mean velocities were measured and MVG calculated during ejection, and early and late diastole, in the endocardium and epicardium on color M-mode Doppler tissue echocardiographic parasternal recordings of the posterior wall, simultaneously imaged with the septum. The population consisted of 34 patients with similar clinical presentation (left ventricular ejection fraction < 40%, left ventricular end-diastolic diameter > 6 cm, and proven ischemic [14] or nonischemic [20] dilated CM) and 16 control subjects.

RESULTS

Doppler tissue echocardiography data significantly differed between control subjects and all patients with CM. Between patients, the only significant differences were found at the posterior wall for mean velocities at the epicardium in systole (9 +/- 4 mm/s for ischemic vs 14 +/- 5 mm/s for nonischemic, P =.002), and at both layers in early diastole (endocardium, 14 +/- 9 vs 29 +/- 12 mm/s, P =.0004; epicardium, 12 +/- 4 vs 22 +/- 11 mm/s, P =.002; ischemic vs nonischemic CM, respectively).

CONCLUSION

Specific features of CM were characterized by myocardial velocity changes studied layer by layer throughout a phase. The binary response of transient peak MVG could not reach this goal.

Myocardial strain rate is a superior method for evaluation of left ventricular subendocardial function compared with tissue Doppler imaging

OBJECTIVES

This study was performed to evaluate subendocardial function using strain rate imaging (SRI).

BACKGROUND

The subendocardium and mid-wall of the left ventricle (LV) play important roles in ventricular function. Previous methods used for evaluating this function are either invasive or cumbersome. Strain rate imaging by ultrasound is a newly developed echocardiographic modality based on tissue Doppler imaging (TDI) that allows quantitative assessment of regional myocardial wall motion.

METHODS

We examined eight sheep using TDI in apical four-chamber views to evaluate the LV free wall. Peak strain rates (SRs) during isovolumic relaxation (IR), isovolumic contraction (IC), and myocardial strain were measured in the endocardial (End), mid-myocardial (Mid), and epicardial (Epi) layers. For four hemodynamic conditions (created after baseline by blood, dobutamine, and metoprolol infusion), we compared differences in SR of End, Mid, and Epi layers to peak positive and negative first derivative of LV pressure (dP/dt).

RESULTS

Strain rate during IC showed a good correlation with +dP/dt (r = 0.74, p < 0.001) and during IR with -dP/dt (r = 0.67, p = 0.0003). There was a significant difference in SR between the myocardial layers during both IC and IR (End: -3.4 +/- 2.2 s(-1), Mid: -1.8 +/- 1.5 s(-1), Epi: -0.63 +/- 1.0 s(-1), p < 0.0001 during IC; End: 2.2 +/- 1.5 s(-1), Mid: 1.0 +/- 0.8 s(-1), Epi: 0.47 +/- 0.64 s(-1), p < 0.0001 during IR). Also, SRs of the End and Mid layers during IC were significantly altered by different hemodynamic conditions (End at baseline: 1.7 +/- 0.7 s(-1); blood: 2.0 +/- 1.1 s(-1); dobutamine: 3.4 +/- 2.3 s(-1); metoprolol: 1.0 +/- 0.4 s(-1); p < 0.05). Myocardial strain showed differences in each layer (End: -34.3 +/- 12.6%; Mid: -22.6 +/- 12.1%; Epi: -11.4 +/- 7.9%; p < 0.0001) and changed significantly in different hemodynamic conditions (p < 0.0001).

CONCLUSIONS

Strain and SR appear useful and sensitive for evaluating myocardial function, especially for the subendocardial region.

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.

Tissue Doppler analysis is hindered in abnormal wall motion and changes in afterload

BACKGROUND

Tissue Doppler (TD) analysis is used to estimate contractility. However, interference with hemodynamics has not been investigated.

OBJECTIVE

To evaluate the effect of hemodynamic conditions and wall motion abnormalities on TD indices.

METHODS

TD indices were obtained in 16 dogs and correlated with hemodynamics and wall thickening.

RESULTS

An inverse relation between TD indices and systemic vascular resistance was observed when afterload-related parameters were included in the analysis (early systolic subendocardial velocity: r((multiple regression))=0.82, P<0.0001 vs. r((simple regression))=0.57, P=0.0002). Early systolic TD data were more closely related to hemodynamics than those derived from the entire systole. TD data did not correspond to the hyperkinesia of the contralateral wall in myocardial infarction, whereas the increase of gradient parameters reflected hypercontractility (P<0.05).

CONCLUSION

TD indices are directly related to contractility and inversely to afterload. They do not reflect wall motion of those segments not involved in regional ischemia.

Novel approach to the quantitation of regional left ventricular systolic and diastolic function using tissue Doppler imaging to create a myocardial velocity profile and gradient

The myocardial velocity profile (MVP) and gradient (MVG) between the endocardium and epicardium of the left ventricular (LV) wall measured by color-coded tissue Doppler imaging (TDI) are new indices for evaluating regional LV myocardial function. However, accurate recording and measurement of the MVP is difficult using conventional methodology because of the stochastic nature of the ultrasound signal; that is, the effect of speckled noise. The aim of this study was to validate the accuracy and establish the validity of a newly developed method for measuring the MVP and MVG using 10 clinically normal controls and 10 patients with a hypertensive hypertrophied LV posterior wall. A non-isotropic, averaging algorithm was developed that was capable of obtaining a stable MVP (averaged MVP). Averaged MVP was recorded using parasternal, LV short-axis, color-coded TDI, placing regions of interest along the LV posterior wall with the reference point for angle-correction being at the center of LV contraction. The velocity from epicardium to endocardium within the region of interest was automatically angle-corrected to calculate the velocity component radially relative to the LV cavity and was spatially averaged along the circumference within the region of interest. Inter- and intraobserber variabilities of measurements were lower in the averaged MVP and MVG than in the conventional MVP and MVG. The correlation coefficients of the linear regression lines of systolic and early diastolic MVPs in the LV posterior wall were higher in all controls and hypertensive patients with the averaged method than with the conventional TDI procedures. The mean peak systolic and early diastolic MVGs were lower in the hypertensive group than in the controls. In conclusion, the newly developed averaged MVP provides a stable and reproducible index for the quantitative assessment of regional LV myocardial function.

Myocardial velocity gradient reflects the severity of myocardial damage regardless of the presence or absence of mitral regurgitation

Complicating mitral regurgitation (MR) apparently enhances left ventricular ejection fraction, thereby leading to the underestimation of myocardial damage by routine echocardiography. We sought to assess the significance of myocardial velocity gradient (MVG) derived from Doppler tissue imaging as an indicator of the severity of myocardial damage in the presence or absence of MR. Peak systolic and diastolic MVG was obtained from 39 participants: 12 healthy participants, 10 patients with dilated cardiomyopathy complicating moderate to severe MR [MR (+) group], and 17 patients with dilated cardiomyopathy without significant MR [MR (-) group]. MVG was compared with standard echocardiographic and Doppler transmitral flow velocity indices. Plasma brain natriuretic peptide levels were measured in all patients. Left ventricular dimension and fractional shortening was similar between MR (+) and MR (-) groups. Plasma brain natriuretic peptide levels were significantly increased in MR (+) group (440 +/- 417 pg/mL) as compared with MR (-) group (122 +/- 107 pg/mL, P <.05). Peak systolic MVG was significantly attenuated in dilated cardiomyopathy group with or without MR [MR (+) group = 1.3 +/- 0.5 seconds(-1), MR (-) group = 2.1 +/- 0.5 seconds(-1), where normal = 4.0 +/- 0.9 seconds(-1), P <.01, respectively]. Peak systolic MVG was further attenuated in MR (+) group than in MR (-) group (P <.01). Plasma brain natriuretic peptide levels were negatively correlated with peak systolic MVG (r = -0.66, P <.0005). Peak diastolic MVG was attenuated in MR (+) and also in MR (-) groups [MR (+) group = -4.5 +/- 2.0 seconds(-1), MR (-) group = -4.4 +/- 1.1 seconds(-1), where normal = -8.7 +/- 2.4 seconds(-1), P <.01, respectively], whereas transmitral flow indices failed to distinguish MR (+) group from normal as a result of pseudonormalization. MVG may reflect the severity of myocardial damage regardless of the presence or absence of complicating MR.

Quantitative assessment of short axis wall motion using myocardial strain rate imaging

Although left ventricular wall motion has been usually assessed with four-point scale (1 = normal; 2 = hypokinesis; 3 = akinesis; 4 = dyskinesis) based on the visual assessment, this method is only qualitative and subjective. Recently, a new echocardiographic system that enables calculation of myocardial strain rate based on tissue Doppler information has been developed. We investigated whether myocardial strain rate could quantify regional myocardial contraction in 17 patients with and without wall motion abnormalities including 6 patients undergoing dobutamine stress echocardiography. Left ventricular short-axis wall motion was assessed with standard two-dimensional echocardiography at basal, mid-ventricular, and apical levels. The same levels were imaged with tissue Doppler method to determine regional myocardial strain rate. Sixty-four segments were judged normokinesis, 53 segments hypokinesis, and 18 segments akinesis at rest; 16 segments were judged normokinesis and 6 segments hypokinesis at stress. No segments characterized dyskinesis. Strain rates of normokinetic, hypokinetic, and akinetic wall segments at rest were significantly different each other (-2.0 +/- 0.6 for normokinesis,-0.6 +/- 0.5 for hypokinesis,P < 0.0001 vs. normokinesis, and-0.008 +/- 0.3 for akinesis, P < 0.0001 vs. normokinesis and hypokinesis). Further, strain rates well reflected the change in wall motion induced by dobutamine challenge: strain rates in the 15 segments revealing augmented wall motion changed from -2.0 +/- 0.7 to -4.7 +/- 1.7 (1/sec) (P < 0.0001) and those in the 7 segments revealing deteriorated or unchanged wall motion changed from -2.1 +/- 1.0 to -1.7 +/- 0.8 (1/sec) (P < 0.05). In conclusion, strain rate agreed well with assessed wall motion. Strain rate imaging may be a new powerful tool to quantify regional wall contraction.

Strain during gastric contractions can be measured using Doppler ultrasonography

This study was undertaken to explore if strain of the muscle layers within the gastric wall could be measured by transabdominal strain rate imaging (SRI), a novel Doppler ultrasound (US) method. A total of 9 healthy fasting subjects (8 women, 1 man; ages 22 to 55 years) were studied and both grey-scale and Doppler US data were acquired with a 5- to 8-MHz linear transducer in cineloops of 97 to 256 frames. Rapid stepwise inflation (5 to 60 mL) of an intragastric bag was carried out and bag pressure and SRI were measured simultaneously. SRI enabled detailed studies of layers within the gastric wall in all subjects. Great variations in strain distribution of the muscle layers were found. Radial strain was much higher in the circular than in the longitudinal muscle layer. Strains derived from SRI correlated well with strains obtained with B-mode measurements (r = 0.98, p < 0.05). During balloon distension, we found an inverse correlation between pressure and radial strain (r = -0.87, p < 0.05). Intraobserver correlation of strain estimation was r = 0.98 (p < 0.05) and intraobserver agreement was 0.2% +/- 18.6% (mean difference +/- 2SD, % strain). Interobserver correlation was r = 0.84 (p < 0.05) and interobserver agreement was 6.9% +/- 56.8%. SRI enables detailed mapping of radial strain distribution of the gastric wall and correlates well with B-mode measurements and pressure increments.

Strain and strain rate echocardiography

Strain and strain rate echocardiography is an emerging technique for assessing myocardial systolic and diastolic function. It is envisioned that this modality could change the quantitative assessment of regional wall motion and improve the accuracy and reproducibility of test readings. Myocardial strain and strain rate can detect inducible ischemia and at earlier stages than visual estimation of wall motion or wall thickening parameters. Changes in systolic strain rate and strain have potential to discriminate between different myocardial viability states. Measurement of diastolic rate of deformation can differentiate physiologic from pathologic hypertrophy, and restrictive from constrictive cardiomyopathy. This article reviews basic principles and current experimental and clinical applications of strain and strain rate echocardiography.

Tissue Doppler imaging for the assessment of left ventricular systolic and diastolic functions

Doppler tissue imaging is a technique that allows recording of the low Doppler shift frequencies of high energy generated by the ventricular walls motion that are purposely filtered out in standard Doppler blood flow studies. Doppler tissue imaging can be performed with the use of pulsed Doppler, color two-dimensional Doppler, and color M-mode Doppler. Pulsed Doppler tissue imaging offers a high temporal resolution and therefore can be appropriately used for analysis of temporal relation between myocardium systolic and diastolic velocity waves. Color two-dimensional Doppler provides a good spatial resolution that permits differentiation of the velocity profiles between subendocardial and subepicardial layers but is limited by its poor temporal resolution. M-mode color-coded tissue imaging is characterized by a high spatiotemporal resolution, but sampling is only performed on a single line. Both two-dimensional and M-mode color-coded tissue imaging require specific modification of the current ultrasound machines. The present article reviews how Doppler tissue imaging may contribute to the noninvasive assessment of systolic and diastolic myocardial functions.

The wall-thinning to transmitral flow-velocity relation: derivation with in vivo validation

Motion of the endocardial surface in diastole is the resultant effect of wall thinning. Endocardial wall motion to transmitral flow (Doppler E-wave) relations that predict wall thinning are derived using conservation of myocardial volume, two simplified (spatiotemporally homogeneous) left ventricular (LV) geometric models and the constant-volume pump attribute of the heart. For validation, model-predicted vs. color M-mode recorded maximum rate of wall thinning was compared in (n = 15) normal controls. Excellent agreement for both models (r = 0.84, r = 0.86) was observed. For abnormal LV function (n = 15), model-predicted vs. M-mode recorded maximum rate of wall-thinning correlated poorly (r = -0.28, r = -0.22). We conclude that, in normal ventricles, the Doppler E-wave and wall thinning are related through the constant-volume attribute of the heart and its geometry. Pathologic cases are governed by the same principles, but the filling to wall-thinning relation is altered by spatiotemporal inhomogeneities in geometry and wall motion.

Quantification of the myocardial velocity gradient and myocardial wall thickening velocity in healthy children: a new indicator of regional myocardial wall motion

Doppler tissue imaging allows the measurement of tissue motion velocity in real time. However, tissue velocities are affected by translational motion and by the angle of Doppler interrogation. The myocardial velocity gradient and myocardial wall thickening velocity, determined by color Doppler tissue imaging, can be used to evaluate regional wall thickening and thinning motion independent of translational motion. To determine the control values for myocardial velocity gradient and myocardial wall thickening velocity for the interventricular septum and posterior wall, we studied 120 healthy children (mean age: 7.8 +/- 5.0 years). Peak values of myocardial velocity gradient and myocardial wall thickening velocity at each cardiac phase were measured: systole, early diastole, and atrial contraction. The peak values of myocardial velocity gradient and myocardial wall thickening velocity were higher in the posterior wall than those in the interventricular septum, suggesting that thickening and thinning are more dynamic in the posterior wall. Linear regression analysis demonstrated that absolute values of myocardial velocity gradient at systole, early diastole, and atrial contraction, and wall thickening velocity at atrial contraction decreased with body surface area (BSA). On the other hand, absolute values of myocardial wall thickening velocity at systole and early diastole increased with BSA, and myocardial wall thickening velocity at early diastole in interventricular septum did not change. Myocardial velocity gradient at systole and early diastole, and myocardial wall thickening velocity at systole were strongly related to BSA. In contrast, myocardial velocity gradient and myocardial wall thickening velocity at atrial contraction strongly correlated with time interval between 2 consecutive QRS complexes. Because myocardial wall thickening velocity at early diastole in the interventricular septum did not correlate with BSA or time interval between 2 consecutive QRS complexes, it might evaluate diastolic function of interventricular septum independent of body size or heart rate.

Doppler-derived myocardial systolic strain rate is a strong index of left ventricular contractility

BACKGROUND

Myocardial fiber strain is directly related to left ventricular (LV) contractility. Strain rate can be estimated as the spatial derivative of velocities (dV/ds) obtained by tissue Doppler echocardiography (TDE). The purposes of the study were (1) to determine whether TDE-derived strain rate may be used as a noninvasive, quantitative index of contractility and (2) to compare the relative accuracy of systolic strain rate against TDE velocities alone.

METHODS AND RESULTS

TDE color M-mode images of the interventricular septum were recorded from the apical 4-chamber view in 7 closed-chest anesthetized mongrel dogs during 5 different inotropic stages. Simultaneous LV volume and pressure were obtained with a combined conductance-high-fidelity pressure catheter. Peak elastance (Emax) was determined as the slope of end-systolic pressure-volume relationships during caval occlusion and was used as the gold standard of LV contractility. Peak systolic TDE myocardial velocities (Sm) and peak (epsilon'(p)) and mean (epsilon'(m)) strain rates obtained at the basal septum were compared against Emax by linear regression. Emax as well as TDE systolic indices increased during inotropic stimulation with dobutamine and decreased with the infusion of esmolol. A stronger association was found between Emax and epsilon'(p) (r=0.94, P<0.01, y=0.29x+0.46) and epsilon'(m) (r=0.88, P<0.01) than for Sm (r=0.75, P<0.01).

CONCLUSIONS

TDE-derived epsilon'(p) and epsilon'(m) are strong noninvasive indices of LV contractility. These indices appear to be more reliable than S(m), perhaps by eliminating translational artifact.

Discriminative ability of conventional echocardiography and tissue Doppler imaging techniques for the detection of subclinical cardiotoxic effects of treatment with anthracyclines

This study investigated improvement of diagnosing myocardial damage caused by anthracyclines using tissue Doppler imaging (TDI). The optimal set of conventional echocardiographic and/or TDI parameters, needed for the discrimination of survivors from healthy controls, was retrospectively assessed. A total of 60 patients and 99 controls, age range 8.5 to 17.6 years, were studied. The survivors received 50 to 400 mg/m(2) cumulative dose of anthracyclines, with a mean follow-up of 7.3 (+/-2.3) years. The parameters used in the discriminant score (S-score) were selected from a large set of 51 echocardiographic parameters, using logistic regression analysis (stepwise selection). The correct classification probability (C-index) and the generalized distance (d) between the distributions of S-scores were used to measure the overall discriminative performance of each echocardiographic technique separately and in combination. The overall discriminative performance of the conventional echo-Doppler parameters (C = 77.3%, d = 1.04) was lower than that of the TDI (C = 84.2%, d = 1.37); the highest C-index was obtained using both techniques (C = 89.2%, d = 1.66). The set of parameters includes: LV fractional shortening and MV early diastolic flow velocity, two long-axis and five apical 4-CV TDI wall velocities (systolic and diastolic). In the patient group, the S-score was positively associated with cumulative dose of anthracyclines (p = 0.05) and duration of treatment (p = 0.01). The diagnostic index S-score, based on a limited number of variables from both techniques simultaneously, could retrospectively discriminate asymptomatic children with anthracycline-induced cardiomyopathy from healthy controls. The potentials of the S-score for serial and prospective studies are further investigated.

Echocardiographic characterization of cardiomyopathy in Friedreich's ataxia with tissue Doppler echocardiographically derived myocardial velocity gradients

BACKGROUND

Conventional and tissue Doppler echocardiographically derived myocardial velocity gradients (MVGs) were used to characterize the myocardium in patients with Friedreich's ataxia (FRDA), and the relationship between MVGs and the mutation in the FRDA gene, a GAA triplet repeat expansion, was investigated.

METHODS AND RESULTS

We studied 29 patients with FRDA (10 men, mean age 31+/-9 years) who were homozygous for the GAA expansion in the FRDA gene and were without cardiac symptoms. A comparison was made with a group of 30 age-matched control subjects. In patients with FRDA, interventricular septal thickness (1.17+/-0.26 versus 0.85+/-0.13 cm, P:<0.005), posterior left ventricular wall thickness (1.00+/-0.24 versus 0.88+/-0.15 cm, P:<0.01), and left atrial diameter (3.3+/-0.5 versus 2.9+/-0.3 cm, P:=0.01) were increased compared with control subjects. MVGs were reduced in FRDA during systole (3.1+/-1.2 versus 4.5+/-0.5 s(-1), P:<0.0001) and in early diastole (4.9+/-2.7 versus 8.8+/-1.8 s(-1), P:<0.0001) but increased in late diastole (2.0+/-1. 3 versus 1.1+/-0.9 s(-1), P:<0.01). The strongest relationship was seen between age-corrected early diastolic MVGs and the GAA expansion in the smaller allele of the FRDA gene (r=-0.68, P:<0. 0001).

CONCLUSIONS

MVGs offer a means of further characterizing the myocardial abnormalities in patients with FRDA. Early diastolic MVGs appear to relate most closely to the genetic abnormality and the consequential reduction in frataxin protein.

Tissue Doppler echocardiography

Tissue Doppler echocardiography (TDE) is a relatively recent addition to the diagnostic ultrasonographic examination. This is similar to routine Doppler ultrasonography to assess blood flow, but technologic features focus on lower velocity frequency shifts. Two techniques are used to assess myocardial function: pulsed TDE and color-coded TDE. A great deal of data has been generated on TDE over the last 5 years, and this review allows for only a small portion of these emerging data to be discussed. One clinical application is to assess peak systolic mitral annular velocity from the apical windows as an index of global ventricular function. The six-site average for peak systolic mitral annular velocity by the color-coded TDE method of greater than 5.4 cm/sec is predictive of an ejection fraction greater than 50% with an 88% sensitivity and a 97% specificity. An emerging application is to use pulsed-TDE to assess ventricular filling pressures. The mitral annular to inflow ratio (E/Ea) greater than 10 is predictive of a mean pulmonary capillary wedge pressure greater than 15 mm Hg with a 92% sensitivity and 80% specificity. Another application is to use peak early diastolic velocity to help differentiate constrictive pericarditis from restrictive cardiomyopathy. Peak early diastolic velocity is blunted with restrictive cardiomyopathy and preserved with constrictive pericarditis. These are just a few of the many evolving clinical applications of this new quantitative diagnostic ultrasonographic method.

Differentiation between restrictive cardiomyopathy and constrictive pericarditis by early diastolic doppler myocardial velocity gradient at the posterior wall

BACKGROUND

The differential diagnosis between restrictive cardiomyopathy (RCM) and constrictive pericarditis (CP) is challenging and, despite combined information from different diagnostic tests, surgical exploration is often necessary.

METHODS AND RESULTS

A group of 55 subjects (mean age, 63+/-11 years; 36 men and 19 women) were enrolled in the study; 15 had RCM, 10 had CP, and 30 were age-matched, normal controls. The diagnosis of RCM was supported by a biopsy; in the CP group, the diagnosis was confirmed either surgically or at autopsy. All patients underwent a transthoracic echocardiogram that included the assessment of Doppler myocardial velocity gradient (MVG), as measured from the left ventricular posterior wall during the predetermined phases of the cardiac cycle. MVG was lower (P<0.01) in RCM patients compared with both CP patients and normal controls during ventricular ejection (2. 8+/-1.2 versus 4.4+/-1.0 and 4.7+/-0.8 s(-1), respectively) and rapid ventricular filling (1.9+/-0.8 versus 8.7+/-1.7 and 3.7+/-1.4 s(-1), respectively). Additionally, during isovolumic relaxation, MVG was positive in RCM patients and negative in both CP patients and normal controls (0.7+/-0.4 versus -1.0+/-0.6 and -0.4+/-0.3 s(-1), respectively; P<0.01). During atrial contraction, MVG was similarly low (P<0.01) in both RCM and CP patients compared with normal controls (1.6+/-1.7 and 1.7+/-1.8 versus 3.8+/-0.9 s(-1), respectively).

CONCLUSIONS

Doppler myocardial imaging-derived MVG, as measured from the left ventricular posterior wall in early diastole during both isovolumic relaxation and rapid ventricular filling, allows for the discrimination of RCM from CP.

Subendocardial motion in hypertrophic cardiomyopathy: assessment from long- and short-axis views by pulsed tissue Doppler imaging

BACKGROUND

Tissue Doppler imaging (TDI) is a recently developed technique that allows the instantaneous measurement of intrinsic regional myocardial motion velocity. Pulsed TDI is capable of separately assessing left ventricular (LV) regional motion velocity caused by circumferential and longitudinal fiber contraction. This particular feature of function is still controversial in patients with hypertrophic cardiomyopathy (HC).

METHODS

To better characterize intrinsic circumferential and longitudinal LV systolic myocardial function in HC, we used pulsed TDI to measure short- and long-axis LV motion velocities, respectively. The subendocardial motion velocity patterns at the middle of the LV posterior wall (PW) and ventricular septum (IVS) in LV parasternal and apical long-axis views were recorded by pulsed TDI in 19 patients with nonobstructive HC and in 21 normal controls (NC).

RESULTS

Peak short- and long-axis systolic subendocardial velocities in both the LV PW and IVS were significantly smaller in the HC group than in the NC group, and the time to peak velocity was significantly delayed. Furthermore, peak PW systolic velocity was significantly greater along the long axis than along the short axis in the NC group (8.8 +/- 1.5 cm/s vs 8.2 +/- 1.4 cm/s, P <.05), whereas the opposite was observed in the HC group (6.1 +/- 1.2 cm/s vs 7.5 +/- 1.0 cm/s, P <.0001). No significant differences were found in either group between the long- and short-axis IVS velocities (HC: 5.9 +/- 1.4 cm/s vs 5.5 +/- 1.3 cm/s; NC: 7.8 +/- 1.3 cm/s vs 7.9 +/- 1.6 cm/s).

CONCLUSIONS

By using the capability of pulsed TDI for the evaluation of intrinsic myocardial velocity instantaneously in a specific region and direction, we found impairment of LV myocardial systolic function in patients with HC not only in the hypertrophied IVS but also in the nonhypertrophied LV PW. We also found a greater decrease in LV PW velocities along the long axis than the short axis, suggesting greater impairment of long-axis contraction in patients with HC. Because our HC patients did not appear to have excessive intracavitary pressure, these results suggest that the relatively normal-appearing PW is directly affected by the HC pathologic process.

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.

The effect of long-term training on age-related left ventricular changes by Doppler myocardial velocity gradient

Myocardial velocity gradient (MVG) derived from Doppler myocardial imaging and standard echocardiographic parameters were used to investigate whether age-related left ventricular (LV) functional and/or structural changes are different in long-term training athletes than in those leading a sedentary life style. Eighty-nine athletes (64 men, mean age 38 years, range 18 to 64) and 105 age-matched sedentary normal subjects were enrolled into the study. The MVG was analyzed in all patients throughout the cardiac cycle, and peak values were measured in systole and in diastole during both rapid ventricular filling and atrial contraction. No differences were found in LV systolic and late diastolic function between athletes and sedentary normal subjects. However, athletes had higher peak E waves in early diastole (73 +/- 10 cm/s vs 68 +/- 10 cm/s, p <0.001) and rapid ventricular filling MVG (10.2 +/- 1.5 s(-1) vs 7.2 +/- 2.8 s(-1), p <0.001) than sedentary normal subjects, suggesting a better early relaxation pattern. From LV diastolic indexes, the rapid ventricular filling MVG age-related decrease was less pronounced in athletes than in sedentary normal subjects (r = -0.39 vs r = -0.91; p <0.01). All other diastolic variables, including transmitral Doppler inflow, had a similar degree of age-related changes in both study groups. Thus, athletes, compared with those leading a sedentary lifestyle, have higher early diastolic performance, which is less affected by the physiologic aging process. It would appear that MVG derived from Doppler myocardial imaging may play an important role in the assessment of LV functional and/or structural changes.

Evaluation of the potential role of color-coded tissue Doppler echocardiography in the detection of allograft rejection in heart transplant recipients

BACKGROUND

Color-coded tissue Doppler (TD) echocardiography can noninvasively quantify alterations in left ventricular (LV) systolic and diastolic function. The objective of this study was to test the hypothesis that TD may play a role in the detection of LV dysfunction associated with allograft rejection in heart transplant recipients.

METHODS AND RESULTS

Seventy-eight consecutive transplant recipients underwent 89 TD studies of posterior wall myocardial velocity gradient and mitral annular velocity within 1 hour of endomyocardial biopsy. Color TD echocardiographic images were digitized for semiautomated computer analysis. Histologic analysis revealed no significant rejection in 75 biopsies and significant rejection in 14. TD posterior wall peak systolic and diastolic velocity gradients were reduced significantly with rejection: 3.9 +/- 2.0 s(-1) versus 2.6 +/- 0.9 s(-1) and 5.4 +/- 2. 4 s(-1) versus 3.5 +/- 1.6 s(-1), respectively (P <.05 vs the nonrejecting group). Peak systolic and diastolic mitral annular velocities by TD were also reduced with rejection: 63 +/- 14 mm/s versus 49 +/- 12.4 mm/s and 90 +/- 23 mm/s versus 60 +/- 21 mm/s, respectively (P <.001 vs the nonrejecting group). A TD peak-to-peak mitral annular velocity >135 mm/s had 93% sensitivity, 71% specificity, and 98% negative predictive value for detecting rejection. Although TD was unable to discriminate between rejection and other causes of low velocity values, high TD velocity values were supportive of excluding rejection.

CONCLUSIONS

These data suggest that color-coded TD may play a potential role as a screening test to exclude rejection in heart transplant recipients. Although this method has the potential to decrease the number of biopsies, further testing in a larger series of transplant recipients with rejection is warranted.

Quantitative Analysis of Tissue Doppler Data

A visual qualitative analysis of color Doppler myocardial images cannot show the low velocity changes in myocardial walls, and a quantitative analysis of tissue Doppler data is mandatory for an analysis of color Doppler myocardial recordings, including an assessment of myocardial velocity gradient across the thickness of the wall. Measurement of myocardial velocity in each pixel should provide access to a broader pathophysiological insight into regional contraction across wall thickness and into all myocardial segments throughout the cardiac cycle.

Myocardial Velocity Gradient Assessed by a Tissue Doppler Imaging Technique

Although tissue Doppler imaging (TDI) is a promising technique for quantitative regional left ventricular wall motion analysis, Doppler angle of incidence and translational motion of the heart influence the velocity measurement by TDI because, in principle, TDI detects the velocity against the transducer. Myocardial velocity gradient (MVG) is derived from TDI as the slope of the regression line for a transmural velocity profile across the myocardial wall, which reflects regional wall thickening and thinning dynamics. Thus, regional diastolic and systolic function may be quantified by using MVG. MVG is also validated to be independent of the translational motion both theoretically and clinically. MVG may therefore be used as an indicator of regional wall motion even under such a condition that the translational motion of the heart cannot be neglected. Our preliminary experience suggests that the quantitative and objective nature of MVG enhances the diagnostic power of stress echocardiography. Further development of the automated, real time processing system and the algorithm for the apical approaches should be awaited for the practical approaches of MVG to be applied to daily clinical practice.

Comparison of 2 myocardial velocity gradient assessment methods during dobutamine infusion with Doppler myocardial imaging

Myocardial velocity gradient (MVG) has been shown to be the best quantitative parameter for the detection of ischemic myocardium during dobutamine infusion with the use of Doppler myocardial imaging. MVG has been previously assessed by velocity measurements across the thickness of the myocardium at the time of visually selected maximal color brightness (thickness-velocity plot method). We hypothesized that MVG could be assessed by velocity measurements throughout the cardiac cycle in the subendocardium parallel to the endocardial boundary to the left ventricular cavity and in the subepicardium parallel to the epicardial boundary (time-velocity plot method). This study was designed to compare MVG obtained from the thickness-velocity plot method and from the time-velocity plot method in quantifying dobutamine-induced changes in myocardial wall motion in 8 phases of the cardiac cycle on color M-mode Doppler myocardial imaging recordings of the left ventricular posterior wall performed in 8 conscious dogs at baseline and at steady state during dobutamine infusion (10 microg/kg per minute). For both methods, MVG was considered present if its mean value was significantly different from zero and if endocardial and epicardial velocities were significantly different. There was close agreement between the 2 methods. MVG was present during the preejection period, systole, rapid ventricular filling, and atrial contraction. Dobutamine induced a significant increase in MVG during the preejection period (from 2.64 +/- 0.83 to 4.05 +/- 0.81 seconds-1 ), systole (from 2.14 +/- 0.59 to 6.08 +/- 2.20 seconds-1 in early systole, from 1.90 +/- 1.06 to 5.31 +/- 2.95 seconds-1 in mid systole, from 1.37 +/- 0.57 to 2.44 +/- 0.53 seconds-1 in end systole), and rapid ventricular filling (from 3.06 +/- 1.12 to 7.82 +/- 2.58 seconds-1 ), related to a greater rise in endocardial than in epicardial velocities. The time-velocity plot method showed that ejection and diastole were 11% and 28% decreased during dobutamine infusion, respectively, as heart rate was 31% increased. Thus according to our quantitative criteria, both MVG assessment procedures enabled objective interpretation of dobutamine effects on left ventricular wall motion. In addition, the time-velocity plot method provided automatic detection of peak velocity, timing, and duration of wall velocity changes over time.

Peak negative myocardial velocity gradient in early diastole as a noninvasive indicator of left ventricular diastolic function: comparison with transmitral flow velocity indices

OBJECTIVES

We sought to assess the clinical significance of peak negative myocardial velocity gradient (MVG) in early diastole as a noninvasive indicator of left ventricular (LV) diastolic function.

BACKGROUND

Peak systolic MVG has been shown useful for the quantitative assessment of regional wall motion abnormalities, but limited data exist regarding the diastolic MVG as an indicator of LV diastolic function.

METHODS

Peak negative MVG was obtained from M-mode tissue Doppler imaging (TDI) in 43 subjects with or without impairment of systolic and diastolic performance: 12 normal subjects, 12 patients with hypertensive heart disease (HHD) with normal systolic performance and 19 patients with dilated cardiomyopathy (DCM), and was compared with standard Doppler transmitral flow velocity indices. In a subgroup of 30 patients, effects of preload increase on these indices were assessed by performing passive leg lifting. In an additional 11 patients with congestive heart failure at the initial examination, the measurements were repeated after 26+/-16 days of volume-reducing therapy.

RESULTS

Peak negative MVG was significantly depressed both in HHD (-3.9+/-1.3/s, p < 0.01 vs. normal=-7.7+/-1.5/s) and DCM (-4.4+/-1.4/s, p < 0.01 vs. normal). In contrast, transmitral flow indices failed to distinguish DCM from normal due to the pseudonormalization. Transmitral flow velocity indices were significantly altered (peak early/late diastolic filling velocity [E/A]=1.1+/-0.5 to 1.5+/-0.7, p < 0.01; E deceleration time=181+/-41 to 153+/-38 ms, p < 0.01), while peak negative MVG remained unchanged (-5.3+/-2.2 to -5.3+/-2.0/s, NS) by leg lifting. Volume-reducing therapy resulted in the apparent worsening of the transmitral flow velocity pattern toward abnormal relaxation, as opposed to peak negative MVG, which improved by the therapy (p < 0.05).

CONCLUSIONS

Peak negative MVG derived from TDI may be a noninvasive indicator of LV diastolic function that is less affected by preload alterations than the transmitral flow velocity indices, and thereby could be used for the follow-up of patients with nonischemic LV dysfunction presenting congestive heart failure.

Pre-ejectional left ventricular wall motions studied on conscious dogs using Doppler myocardial imaging: relationships with indices of left ventricular function

Duration of the pre-ejection period is a sensitive index of myocardial function. Our purpose was to document normal pre-ejectional left ventricular (LV) wall motions at rest and under dobutamine using Doppler myocardial imaging (DMI), and to correlate posterior wall velocities with indices of LV systolic function. M-mode recordings of both walls were imaged on eight conscious dogs chronically instrumented. Subendocardial pre-ejectional velocities were digitized and measured every 3.8 ms. DMI analysis consisted of sign recognition, velocity measurement, duration and timing from the Q wave of the electrocardiogram. Isovolumic contraction time (Ict) was represented by the time interval from onset to peak of the first derivative of LV pressure. Conventional Doppler labelling of velocity signs, positive toward and negative away from the transducer, was applied to the direction of encoded wall motions. For physiological understanding, wall motions of both walls were also labelled inward and outward with respect to the left ventricular cavity center. In each wall, PEP was shown as several colored strips, each strip representing the period of time that the wall was moving in one direction. Changes in velocity sign corresponding to changes in direction of motion were opposed in each wall (p < 0.001), featuring successive inward and outward wall motions. There was a markedly sustained inward motion during Ict. Its velocity amplitude increased with dobutamine. There was a positive correlation between velocities of the inward motion contemporaneous of Ict and ejection fraction (r = 0.72, p < 0.003). Values of Ict respectively drawn from DMI and from hemodynamics were also significantly correlated (r = 0.85, p < 0.007). Thus, the inward motion evidenced by DMI during Ict appears promising to assess myocardial function and effect of drugs.

Tissue Doppler imaging and the quantification of myocardial function

Tissue Doppler imaging (TDI) has recently been introduced in clinical echocardiography. Most widely used are tissue velocity maps, in which the velocity of moving tissue is calculated relative to the transducer from the Doppler shift and displayed as colour-encoded velocity maps in either M-mode or two-dimensional image formats (Doppler velocity mode). This allows detection and quantification of dyssynergic areas of the myocardium. Additionally, the velocities may be studied with pulsed wave-tissue Doppler sampling (PW-TDS) which displays the velocity of a selected myocardial region versus time with high temporal resolution. Less often used, are tissue acceleration maps which display acceleration or velocity change of subsequent frames as different colours (Doppler acceleration mode). These maps may find application in clinical electrophysiology. Another TDI modality is tissue energy imaging, which is based on the integration of the power spectrum of the Doppler signals from the tissue. This technique provides maps of Doppler energy which are represented as colour brightness. Such maps offer potential for the study of myocardial perfusion. TDI modalities have promise to become clinically useful for quantifying myocardial function.

Quantification of the myocardial response to low-dose dobutamine using tissue Doppler echocardiographic measures of velocity and velocity gradient

Low-dose dobutamine echocardiography has been clinically useful in myocardial viability studies, although routine visual assessment of wall motion is subjective. The objective was to quantify the incremental myocardial response to low-dose dobutamine infusion using a new semiautomated tissue Doppler (TD) analysis system and to compare these data with routine echocardiographic measures in the same subjects. Twelve subjects had TD and routine echocardiographic studies at baseline and during 10-minute stages of dobutamine infusion at 1, 2, 3, and 5 microg/kg/min. Color TD video data were converted to a digital velocity matrix (4.5 velocity data points/mm at 500 Hz) for analysis of mitral annular velocity, endocardial velocity, and velocity gradient at each stage. Posterior wall percent thickening and ejection fraction were calculated from the routine images. Mitral annular peak systolic velocity significantly increased with only 1 microg/kg/min of dobutamine from 69 +/- 9 to 77 +/- 7 mm/s (p <0.05 vs baseline), and further incremental increases occurred with each subsequent dose. Anteroseptal and posterior wall peak endocardial velocity increased with 2 microg/kg/min of dobutamine from 33 +/- 7 to 46 +/- 15 mm/s and 50 +/- 9 to 61 +/- 10 mm/s, respectively (p <0.01 vs baseline) and further increased with 5 microg/kg/min (p <0.0001 vs 3 microg/kg/min). Posterior wall peak systolic gradient also increased with 2 microg/kg/min of dobutamine from 3.1 +/- 0.6 to 5.4 +/- 1.6 s(-1) (p <0.05 vs baseline). Routine measures of percent wall thickening or ejection fraction did not detect increases until the 3 microg/kg/min dose. TD can detect subtle alterations in contractility induced by low-dose dobutamine and has the potential to quantify regional ventricular function objectively.

Comparative usefulness of myocardial velocity gradient in detecting ischemic myocardium by a dobutamine challenge

OBJECTIVES

We tested the hypothesis that ischemic myocardium can be sensitively detected using tissue Doppler-derived myocardial velocity gradient (MVG) by a dobutamine challenge.

BACKGROUND

Although tissue Doppler imaging (TDI) has recently emerged to quantify regional myocardial contraction, increased translational motion during a dobutamine challenge may affect the measurements. MVG is an indicator of regional myocardial contraction independent of the translational motion.

METHODS

We studied 19 patients with (n = 13) and without (n = 6) confirmed single-vessel coronary artery disease. Left ventricular short-axis tissue Doppler images were obtained along with conventional echocardiograms during a submaximal two-step dobutamine challenge (10 and 30 microg/kg body weight per min). Endocardial velocity as well as MVG were derived from TDI using computer analysis in the anteroseptal and posterior segments and were compared with visual interpretation.

RESULTS

MVG demonstrated a significant dose-responsive increase in the nonischemic segments (anteroseptal: 2.6 +/- 0.8/s to 6.0 +/- 1.0/s [mean +/- SD], p < 0.05; posterior: 3.9 +/- 0.7/s to 7.6 +/- 1.8/s, p < 0.05) but remained unchanged in the ischemic segments (anteroseptal: 2.5 +/- 0.8/s to 2.7 +/- 0.7/s, p = NS; posterior: 3.4 +/- 1.0/s to 4.1 +/- 0.9/s, p = NS). Endocardial velocity failed to clearly demonstrate the differing responses between the nonischemic (anteroseptal: -2.3 +/- 1.2 to -2.7 +/- 1.6 cm/s, p = NS; posterior: 3.8 +/- 1.1 to 73 +/- 2.7 cm/s, p < 0.05) and ischemic segments (anteroseptal: -2.1 +/- 0.5 to -2.8 +/- 0.8 cm/s, p = NS; posterior: 4.2 +/- 0.8 to 6.5 +/- 2.6 cm/s, p = NS). Wall motion abnormality was hardly detectable with visual interpretation (wall motion score range 1.00 to 1.33).

CONCLUSIONS

Abnormal segments could be sensitively detected by using MVG in a submaximal dobutamine challenge, even where conventional methods failed to detect the abnormality.