A videodensitometric study of transmural heterogeneity of cyclic echo amplitude variation in human myocardium

A Comparison of the Performance of Myocardial Videodensitometry, Tissue Velocity Imaging and Tissue Tracking in Discrimination Between ST-Segment Elevation Ischemic Reperfusion Injury and Normal Reperfusion State After Non-Beating Cardiac Operation

Background:

The timely diagnosis of presence or absence of reperfusion injury after cardiac operation is critical for the patient’s outcome. Whether transesophageal echocardiography (TEE) acquisition of regional grayscale intensity (TI), velocity, and displacement (D) after cardiac operation can discriminate between patients with ST-segment elevation ischemic reperfusion injury (STEIRI) and normal reperfusion state remains unknown.

Objectives:

In this study, we investigated whether these parameters can effectively reflect the situation of ST-segment elevation ischemic reperfusion injury (STEIRI) in patients after cardiac operation and which has a higher performance of discrimination between patients with and without STEIRI.

Patients and Methods:

The maximal and minimal grayscale intensity in the cardiac cycle [TI (max), TI (min)], the difference of TI (max) and TI (min) [TI (max-min)], the cyclic variation index of TI [TI (CVI)], the systolic velocity (Vs), the early diastolic velocity (Ve), the late diastolic velocity (Va) and the peak displacement in the cardiac cycle (D) at the lateral side of the mitral annulus were measured and compared between patients with and without STEIRI. The performance of these parameters in discriminating between patients with and without STEIRI was analyzed.

Results:

Compared with the patients without STEIRI, the patients with STEIRI had significantly smaller TI (max-min), TI (CVI), Vs, Ve, Va and D (P<0.05). With the use of these parameters as the criteria to distinguish patients with STEIRI from patients without STEIRI, the areas under the receiver operating characteristic curve were 0.86 for TI (max-min), 0.99 for TI (CVI), 0.89 for Vs, 0.71 for Ve, 0.85 for Va and 0.82 for D. For the best cut-off value of TI (CVI) of less than 34.45%, the sensitivity, specificity and accuracy for the prediction of patients with STEIRI were 94.74%, 97.05%, and 96.22%, respectively.

Conclusion:

The myocardial grayscale intensity, velocity and displacement can effectively reflect the situation of STEIRI in patients after cardiac operation, and TI (CVI) has a higher performance in discriminating between patients with and without STEIRI.

Acoustic videodensitometric parameters correlate with abnormalities of left ventricular filling in hypertensive patients assessed via Doppler Tissue Imaging

PURPOSE

Using a videodensitometric technique developed in our center we investigated whether the amplitude of variation of gray levels in the interventricular septum was related to functional parameters, especially ventricular filling as studied by doppler tissue imaging (DTI) in hypertensive patients.

METHODS AND RESULTS

We included 35 hypertensive patients from whom we recorded a two dimensional sequence of the left ventricle from the short axis parasternal view and a doppler tissue scan of the mitral ring. Two-dimensional sections were then analyzed with Iodp software to measure variations in levels of gray in the septum. We observed significant correlations between these variations and the velocity of the Ea wave on DTI of the lateral wall (r = 0.49, p < 0.002). On dividing this population into three sub-groups according to the Appleton classification of ventricular filling, we noted a tendency to a reduction in amplitude of variations of gray of the septum in cases with abnormalities of relaxation. This was even more marked in cases with a restrictive or pseudo-normal profile.

CONCLUSION

These observations point to the interest of sonographic videodensitometry in the evaluation of hypertensive cardiopathy. Further studies will be required to determine whether it can define the extent of the abnormalities of myocardial structure and the degree of fibrosis.

Potential relationships among myocardial stiffness, the measured level of myocardial backscatter (“image brightness”), and the magnitude of the systematic variation of backscatter (cyclic variation) over the heart cycle

BACKGROUND

In a number of recently published studies comparing measurements from patients with those from control subjects, a decreased magnitude of the systematic variation of backscattered energy over the heart cycle (cyclic variation) is accompanied by an increased level of overall myocardial backscatter (calibrated myocardial image brightness) when measured at a specific phase of the heart cycle (eg, end systole or end diastole). The goal of this study was to investigate whether this observation is consistent with predictions based on a model of the mechanisms of cyclic variation incorporating changes in relative intracellular and extracellular acoustic impedance over the heart cycle.

METHODS

A previously described 3-component Maxwell-type model of muscle mechanics representing cardiac cell mechanical behavior was utilized to predict the systematic variation in the relative acoustic impedance differences between intracellular and extracellular elastic properties over the heart cycle and hence the observed magnitude of cyclic variation and overall myocardial scattering level. Predictions were obtained for a series of specific values of relative intracellular and extracellular acoustic impedance.

RESULTS

Results indicate that the predicted magnitude of cyclic variation can be directly related to the overall myocardial backscatter level. For example, specific changes in the acoustic impedance (stiffness properties) of the extracellular matrix without any change in the intracellular acoustic impedance result in predicted values of -43.5 dB, -38.5 dB, and -33.5 dB for end-diastolic myocardial backscatter levels with corresponding values of 5.0 dB, 2.5 dB, and 1.3 dB for the predicted magnitude of cyclic variation, respectively.

CONCLUSION

This study suggests that observed decreases in the magnitude of cyclic variation with concomitant increases in the measured overall myocardial backscatter level are consistent with predictions from a model based on the relative acoustic impedance differences between intracellular and extracellular elastic properties over the heart cycle. These results suggest that ultrasonic backscatter measurements may provide a noninvasive approach for assessing some relationships among myocardial stiffness, degree of fibrosis, and contractile performance.

Analysis of transmural trends in myocardial integrated backscatter in patients with progressive systemic sclerosis

Cardiac involvement in progressive systemic sclerosis (PSS) is common and has a strong negative impact on the prognosis, especially when autoantibodies are present. To determine whether ultrasonic tissue characterization can detect early ultrastructural changes in the sclerodermal myocardium, we analyzed the transmural heterogeneity in myocardial integrated backscatter (THIB). "A-THIB" was defined as the absolute difference in integrated backscatter between the left (subendocardial) and right (subepicardial) ventricular halves of the myocardium in the septum and posterior wall, and was measured in 11 patients with PSS and 10 age- and sex-matched healthy participants. A-THIB in patients with PSS was higher than that in healthy participants (1.3 +/- 1.3 vs 4.0 +/- 1.4 dB for the septum and 1.1 +/- 0.7 dB vs 2.8 +/- 0.4 dB for the posterior wall; mean +/- SD, respectively, P <.0005). Septal A-THIB was higher in patients with PSS with than without anti-Scl70 or antinucleolar antibodies (3.2 +/- 1.1 vs 5.0 +/- 1.0 dB, P =.0165). Early changes in the myocardium of patients with PSS, possibly related to increased interstitial collagen deposition, can be detected by quantitative analysis of THIB.

Myocardial texture analysis in idiopathic dilated cardiomyopathy: prediction of contractile reserve on dobutamine echocardiography

Conventional resting echocardiography is not able to predict contractile reserve (CR) of patients with idiopathic dilated cardiomyopathy. The aim of this study was to investigate whether the videodensitometric myocardial texture analysis could predict the CR of these patients. Myocardial texture analysis was performed on echocardiographic digitized images of 27 patients with IDC through a calibrated 256 gray level digitization system. Cyclic variation (CV) index of myocardial mean gray level (MGL) was calculated according to the formula: (MGL(diast) - MGL(syst))/ MGL(diast) x 100. CR was defined as the %-change of ejection fraction by 10 microg/kg per minute dobutamine infusion. A clinical follow-up was also performed for all patients for an average of 8 +/- 3 months. CR ranged from -1.8% to 50.3%. CV index of both septum and posterior wall (PW) was the single parameter significantly correlated to CR (r = 0.69 and r = 0.77, respectively, P <.0001 for both). The mean resting CV index of septum and PW were significantly lower in patients with CR less than 17%-median value of all subjects-(5.7 +/- 5.6 vs 16.9 +/- 7.9 and 5.4 +/- 5.9 vs 16.1 +/- 6.4, respectively, P <.0001 for both). A CV index of 10% for both septum and PW yielded a sensitivity of 77% and 84%, and a specificity of 84% and 84% for predicting diminished CR, respectively. The event-free survival rate was significantly lower in patients with CR less than 17% (61.5% vs 92.8%, P <.05). The CV index of both septum and PW were also significantly lower in patients with cardiac events (13.6 +/- 8 vs 4.3 +/- 6, P <.05 and 14.7 +/- 7 vs 4.1 +/- 7, P <.01, respectively). Ultrasonic myocardial texture analysis in idiopathic dilated cardiomyopathy has a high ability to discriminate the patients with and without preserved CR, and patients with unfavorable outcome as well.

Stress-induced changes in subendocardial tissue texture in hypertrophic cardiomyopathy: an echocardiographic videodensitometric study

BACKGROUND

Myocardial ischemia changes myocardial acoustic properties, inducing increase of integrated backscatter and blunting of cyclic variation of backscatter. Stress-induced subendocardial underperfusion has been demonstrated in patients with hypertrophic cardiomyopathy (HCM).

AIM

To evaluate the potential of a videodensitometric approach in assessing transmural ultrasonic tissue changes in HCM during dipyridamole infusion.

METHODS

Twenty-two patients (13 males, 50+/-12 years) with HCM underwent dipyridamole echo testing (DET). Myocardial gray levels amplitude was calculated off-line on digitized images in the left subendocardial (LV-endo), right subendocardial (RV-endo) region of the interventricular septum and posterior wall (long axis parasternal view).

RESULTS

The thickness of the interventricular septum and posterior wall was 1.9+/-0.3 and 1.17+/-2.1 cm, respectively. In the LV-endo layer, the cyclic variation was blunted during DET (rest = 37+/-14 vs. DET 27+/-20%, p < 0.02). In the RV-endo layer and posterior wall, no changes occurred. In the LV-endo layer of the septum, blunting of cyclic variation was more pronounced in the 10 patients with than in the 12 without ST-segment depression during DET (21.2+/-14.7% vs. 43.8+/-15.8, p < 0.01).

CONCLUSIONS

In HCM patients, DET induced blunting of cyclic variation without the evidence of wall motion abnormalities. This reduction was more pronounced when electrocardiographic signs of ischemia were simultaneously elicited by DET.

Ultrasonic myocardial textural analysis in subclinical hypothyroidism

BACKGROUND

In subclinical hypothyroidism (sHT), a condition in which impaired hormone synthesis is compensated by thyroid-stimulating hormone (TSH) hypersecretion, previous studies have suggested the presence of disturbances in left ventricular (LV) function.

OBJECTIVES

Our goal was to investigate LV structure and function through the combined use of conventional Doppler echocardiography and ultrasonic videodensitometry.

METHODS

We studied 16 patients with sHT (aged 32+/-12 [mean +/- SD] years) who had raised TSH levels (> 3.6 mIU/L) but normal levels of free thyroid hormones (free thyroxine [FT(4)] and free triiodothyro-nine [FT(3)]), and 16 carefully age- and sex-matched euthyroid subjects. Transmitral flow Doppler analysis and quantitative analysis of the echocardiographic digitized images were performed in all study subjects. Textural parameters of the septum and posterior wall were obtained as mean gray levels, which were then used to calculate the cyclic variation index (CVI), that is, the percent change in mean gray levels between diastole and systole.

RESULTS

Patients with sHT had a significantly higher LV mass index (92 +/- 16 versus 76 +/- 16 g.m(2), P<.01) and isovolumic relaxation time corrected for heart rate (IVRTc) (2.9 +/- 0.6 versus 2.5 +/- 0.6, P<.04) than did controls. On videodensitometry, patients had lower CVIs both for the septum (-5% +/- 22% versus 33% +/- 9%, P<.0001) and the posterior wall (10% +/- 26% versus 49% +/- 18%, P<.0001). IVRTc discriminated only 25% of the patients from the controls, whereas CVI analysis correctly identified 85% of the patients with sHT (P<.002). Furthermore, CVI values were found to be significantly related to serum FT(4) and FT(3) concentrations in a direct fashion, and to serum TSH levels in an inverse fashion.

CONCLUSIONS

Subclinical hypothyroidism is associated with changes in videodensitometric myocardial structure. These changes, which are not accurately detected by conventional or Doppler echocardiography, are quantitatively related to loss of thyroid function and could represent an early sign of myocardial damage in hypothyroidism.

Effects of acute myocardial ischemia on intramyocardial contraction heterogeneity: A study performed with ultrasound integrated backscatter during transesophageal atrial pacing

BACKGROUND

[corrected] Subendocardial thickening is greater than subepicardial thickening and acute myocardial ischemia mainly impairs the former. Integrated backscatter cyclic variations (IBScv) reflect regional myocardial contractility and are blunted during myocardial ischemia. We hypothesized that stress-induced myocardial ischemia mainly affects subendocardial IBScv.

METHODS AND RESULTS

Multiplane transesophageal echocardiography and simultaneous atrial pacing were performed in 12 patients without coronary artery disease (CAD) and in 25 with significant CAD. In a transgastric 2-chamber view, we calculated IBScv in subendocardium and subepicardium and a heterogeneity index, both at rest and at peak-pacing. In 27 myocardial segments of patients with normal coronary arteries, and in 16 myocardial segments supplied by coronary artery without significant stenosis in patients with CAD, there was a transmural gradient of IBScv at rest and the heterogeneity index did not change during all the protocol steps. In the 53 myocardial segments related to a significantly narrowed coronary artery, the transmural gradient of IBScv, present at rest, significantly decreased at peak-pacing because of subendocardial blunting, but promptly recovered 5 seconds after pacing interruption. Moreover, the myocardial thickening at rest and peak pacing correlated with the subendocardial IBScv behavior and not with the subepicardial one.

CONCLUSIONS

IBScv are greater in the subendocardium than in the subepicardium. Atrial pacing stress test does not affect IBScv in segments supplied by nonstenotic coronary arteries, whereas it affects segments supplied by diseased coronary arteries, blunting exclusively subendocardial IBScv. Heterogeneity of IBScv intramyocardial changes caused by stress-induced ischemia must be taken into account when using IBScv for investigating myocardial ischemia.

Increased myocardial echo density in left ventricular pressure and volume overload in human aortic valvular disease: an ultrasonic tissue characterization study

Quantitatively assessed ultrasonic backscatter is an index of ultrasonic tissue characterization directly related to morphometrically evaluated collagen in human beings. Our objective was to assess myocardial reflectivity pattern of patients with severe left ventricular hypertrophy caused by either aortic stenosis (AS) or aortic regurgitation (AR). Ten patients with AS, 10 patients with AR, and 10 closely age- and gender-matched healthy controls were studied by two-dimensional Doppler echocardiography. By using an echocardiographic prototype, we performed a radiofrequency analysis to obtain quantitative operator-independent measurements of the integrated backscatter signal of the ventricular septum and the posterior wall (integrated backscatter index: IBI, expressed in percentage). All patients with stenosis or aortic insufficiency showed a normal regional and global resting systolic function (fractional shortening: AS = 36.0 +/- 6.6 versus AR = 40.3 +/- 6.2 versus control = 40.2 +/- 8.7; p = not significant [NS]) Left ventricular mass index (Devereux's formula) was markedly increased in patients with stenosis or aortic insufficiency (AS = 199.3 +/- 18 versus AR = 208.8 +/- 60 versus control = 97.3 +/- 11 g/m2; p < 0.0001). Myocardial echo density was increased in patients with stenosis or aortic insufficiency in comparison with controls, both in the septum (IBI%: AR = 40.7 +/- 7.9 versus AS = 33.4 +/- 4.2 versus control = 23.0 +/- 6.2; p < 0.0001) and in the posterior wall (IBI%: AR = 27.1 +/- 4.3 versus AS = 23.0 +/- 2.6 versus control = 15.0 +/- 4.2; p < 0.0001). No significant correlations were found between septal and posterior wall IBI and their thickness. Abnormally increased myocardial echo density--possibly related to disproportionate collagen deposition--can be detected in patients with pressure or volume overload caused by aortic valve disease and without overt systolic dysfunction.