Normal ultrasonic myocardial reflectivity in athletes with increased left ventricular mass. A tissue characterization study

Sports activities and cardiovascular system change

Sports activity is generally considered to be beneficial to health. The World Health Organization (WHO) recommends physical activity as part of a healthy lifestyle. Sports activities significantly affect the cardiovascular system. A number of studies show that they significantly reduce the risk of cardiovascular disease as well as decrease cardiovascular mortality. This review discusses changes in various cardiovascular parameters in athletes - vagotonia/bradycardia, hypertrophy of heart, ECG changes, blood pressure, and variability of cardiovascular parameters. Because of its relationship to the cardiovascular system, VO2max, which is widely used as an indicator of cardiorespiratory fitness, is also discussed. The review concludes with a discussion of reactive oxygen species (ROS) and oxidative stress, particularly in relation to changes in the cardiovascular system in athletes. The review appropriately summarizes the above issues and points out some new implications.

Impact of endurance exercise on the heart of cyclists: A systematic review and meta-analysis

OBJECTIVE

To compare heart structure and function in endurance athletes relative to participants of other sports and non-athletic controls in units relative to body size. A secondary objective was to assess the association between endurance cycling and cardiac abnormalities.

PATIENTS AND METHODS

Five electronic databases (CINAHL, Cochrane Library, Medline, Scopus, and SPORTdiscus) were searched from the earliest record to 14 December 2019 to identify studies investigating cardiovascular structure and function in cyclists. Of the 4865 unique articles identified, 70 met inclusion criteria and of these, 22 articles presented 10 cardiovascular parameters in units relative to body size for meta-analysis and five presented data relating to incidence of cardiac abnormalities. Qualitative analysis was performed on remaining data. The overall quality of evidence was assessed using GRADE. Odds ratios were calculated to compare the incidence of cardiac abnormality.

RESULTS

Heart structure was significantly larger in cyclists compared to non-athletic controls for left ventricular: mass; end-diastolic volume, interventricular septal diameter and internal diameter; posterior wall thickness, and end-systolic internal diameter. Compared to high static and high dynamic sports (e.g., kayaking and canoeing), low-to-moderate static and moderate-to-high dynamic sports (e.g., running and swimming) and moderate-to-high static and low-to-moderate dynamic sports (e.g., bodybuilding and wrestling), endurance cyclists end-diastolic left ventricular internal diameter was consistently larger (mean difference 1.2-3.2 mm/m²). Cardiac abnormalities were higher in cyclists compared to controls (odds ratio: 1.5, 95%CI 1.2-1.8), but the types of cardiac abnormalities in cyclists were not different to other athletes.

CONCLUSION

Endurance cycling is associated with a larger heart relative to body size and an increased incidence of cardiac abnormalities relative to controls.

Level of Physical Activity, Left Ventricular Mass, Hypertension, and Prognosis

Left ventricular hypertrophy is a strong predictor of prognosis in hypertension. Physical activity is associated with higher left ventricular mass but also reduced risk of cardiovascular outcomes. The aims were to explore whether (1) presence of hypertension modifies the association between physical activity and left ventricular mass; (2) the beneficial association between physical activity and prognostic outcome is modified by left ventricular hypertrophy. Randomly selected number of 3078 persons from the general population underwent echocardiogram. Left ventricular mass was indexed to body surface area. Level of physical activity was self-reported: inactivity, light activity, and moderate/high activity. Blood pressure was measured in rest: normal BP (<140/90 mm Hg) and hypertension (≥140/90 mm Hg or in pharmacological treatment for hypertension). Presence of hypertension modified the association between physical activity and left ventricular mass index significantly (test for interaction: P =0.01): in normal BP, higher levels of physical activity were associated with significantly higher left ventricular mass index ( P <0.001), but this was not present in hypertension ( P =0.90). Level of physical activity was associated with reduction in mortality and cardiovascular outcome independent of the presence of LVH (Persons with LVH: light activity HR, 0.77 [0.52–1.15], moderate/high activity HR, 0.61 [0.38–0.97]; test for interaction between LVH and level of physical activity P =0.71). In conclusion, persons with normal BP had higher left ventricular mass index at increased levels of physical activity, whereas this association was not present among persons with hypertension. Level of physical activity was associated with better prognosis independent of whether left ventricular hypertrophy was present or not.

Understanding Key Mechanisms of Exercise-Induced Cardiac Protection to Mitigate Disease: Current Knowledge and Emerging Concepts

The benefits of exercise on the heart are well recognized, and clinical studies have demonstrated that exercise is an intervention that can improve cardiac function in heart failure patients. This has led to significant research into understanding the key mechanisms responsible for exercise-induced cardiac protection. Here, we summarize molecular mechanisms that regulate exercise-induced cardiac myocyte growth and proliferation. We discuss in detail the effects of exercise on other cardiac cells, organelles, and systems that have received less or little attention and require further investigation. This includes cardiac excitation and contraction, mitochondrial adaptations, cellular stress responses to promote survival (heat shock response, ubiquitin-proteasome system, autophagy-lysosomal system, endoplasmic reticulum unfolded protein response, DNA damage response), extracellular matrix, inflammatory response, and organ-to-organ crosstalk. We summarize therapeutic strategies targeting known regulators of exercise-induced protection and the challenges translating findings from bench to bedside. We conclude that technological advancements that allow for in-depth profiling of the genome, transcriptome, proteome and metabolome, combined with animal and human studies, provide new opportunities for comprehensively defining the signaling and regulatory aspects of cell/organelle functions that underpin the protective properties of exercise. This is likely to lead to the identification of novel biomarkers and therapeutic targets for heart disease.

Left ventricular hypertrophy in athletes and hypertensive patients

Systemic hypertension and physical exercise are both associated with cardiac adaptations. The impact is most prominent on the left side of the heart, which hypertrophies leading to left ventricular hypertrophy. This article reviews structural and functional cardiac changes seen in hypertensive and athlete's hearts.

Behavior of repolarization variables during exercise test in the athlete's heart

BACKGROUND

T peak-T end, QT peak/QT ratio and T peak-T end/QT ratio are markers able to test myocardial repolarization homogeneity, their increase has been related to a higher risk of ventricular tachyarrhythmias. These parameters have not yet been studied in left ventricular hypertrophy due to training. Aim of the research was to test the behavior of these variables in the athlete's heart during exercise.

METHODS

We examined 70 athletes, all males, divided into two groups according to the absence or the presence of a left ventricular mass index over 49 g/m(2.7) and a control group composed of 35 healthy, untrained males. All study participants underwent electrocardiogram at rest, transthoracic echocardiogram, and ergometric test. Repolarization markers (QT, corrected QT, QT dispersion, T peak-T end, QT peak/QT, T peak-T end/QT) were calculated at rest, at peak exercise and during recovery.

RESULTS

There was no statistically significant difference among the groups regarding all the parameters studied, except for corrected QT at rest between athletes with left ventricular hypertrophy and control group. The behavior of repolarization markers during exercise was not dissimilar in the three groups.

CONCLUSIONS

Athlete's heart is not associated to any alteration in ventricular repolarization homogeneity, neither at rest nor during physical activity nor during recovery. Training-induced left ventricular hypertrophy does not affect relationship QT parameters/RR interval.

The Athlete's Heart vs. the Failing Heart: Can Signaling Explain the Two Distinct Outcomes?

Cardiac remodeling is typically associated with disease and can lead to heart failure. In contrast, remodeling that occurs in the athlete's heart is considered an adaptive physiological response. This review provides an overview of signaling mechanisms responsible for inducing left ventricular hypertrophy in the athlete's heart and in settings of pathological hypertrophy and heart failure.

Myocardial ultrasonic tissue characterization in patients with thyroid dysfunction

Background

Structural myocardial abnormalities have been extensively documented in hypothyroidism. Experimental studies in animal models have also shown involvement of thyroid hormones in gene expression of myocardial collagen. This study was planned to investigate the ability of ultrasonic tissue characterization, as evaluated by integrated backscatter (IBS), to early identify myocardial involvement in thyroid dysfunction.

Patients and Methods

We studied 15 patients with hyperthyroidism (HYPER), 8 patients with hypothyroidism (HYPO), 14 patients with subclinical hypothyroidism (SCH) and 19 normal (N) subjects, who had normal LV systolic function. After treatment, 10 HYPER, 6 HYPO, and 8 SCH patients were reevaluated. IBS images were obtained and analyzed in parasternal short axis (papillary muscle level) view, at left ventricular (LV) posterior wall. The following IBS variables were analyzed: 1) the corrected coefficient (CC) of IBS, obtained by dividing IBS intensity by IBS intensity measured in a rubber phantom, using the same equipment adjustments, at the same depth; 2) cardiac cyclic variation (CV) of IBS - peak-to-peak difference between maximal and minimal values of IBS during cardiac cycle; 3) cardiac cyclic variation index (CVI) of IBS - percentual relationship between the cyclic variation (CV) and the mean value of IBS intensity.

Results

CC of IBS was significantly larger (p < 0.05) in HYPER (1.57 ± 0.6) and HYPO (1.53 ± 0.3) as compared to SCH (1.32 ± 0.3) or N (1.15 ± 0.27). The CV (dB) (HYPO: 7.5 ± 2.4; SCH: 8.2 ± 3.1; HYPER: 8.2 ± 2.0) and the CVI (HYPO: 35.6 ± 19.7%; SCH: 34.7 ± 17.5%; HYPER: 37.8 ± 11.6%) were not significantly different in patients with thyroid dysfunction as compared to N (7.0 ± 2.0 and 44.5 ± 15.1%).

Conclusions

CC of IBS was able to differentiate cardiac involvement in patients with overt HYPO and HYPER who had normal LV systolic function. These early myocardial structural abnormalities were partially reversed by drug therapy in HYPER group. On the other hand, although mean IBS intensity tended to be slightly larger in patients with SCH as compared to N, this difference was not statistical significant.

Integrated backscatter of the brain of preterm infants

We measured integrated backscatter (IBS) in the brain of preterm infants using acoustic ultrasound. The study group consisted of 25 preterm infants (gestational age, 32.4+/-2.5 weeks; birth weight, 1488+/-422 g). In parasagittal scans through the posterior horn of the lateral ventricle, regions of interest (ROI) were positioned in the cerebral white matter near the posterior horn (P), anterior horn (A) of the lateral ventricle, and the thalamus (T). IBS of the ROI was measured and IBS of P minus T (P-T) and IBS of A minus T (A-T) were calculated. A-T was greater than P-T. A-T and P-T decreased with increasing gestational age and birth weight. These changes may represent maturation of the cerebrum. A-T or P-T may be useful parameters of cerebral tissue characterization.

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.

Impact of the angiotensin II receptor antagonist, losartan, on myocardial fibrosis in patients with end-stage renal disease: assessment by ultrasonic integrated backscatter and biochemical markers

Myocardial fibrosis commonly occurs in patients with end-stage renal disease (ESRD) and has proven to be an important predictor for cardiovascular events. In experimental settings, angiotensin II type 1 receptor (AT1-R) antagonists have been shown to have anti-fibrotic effects on the myocardium independent of their antihypertensive effects. In this study, to investigate whether the AT1-R antagonist losartan would have such anti-fibrotic effects in patients, we administered losartan or, for purpose of comparison, the angiotensin-converting enzyme enalapril or Ca2+-antagonist amlodipine to patients with ESRD. Thirty-nine ESRD patients with hypertension were randomly assigned to receive losartan (n=13), enalapril (n=13), or amlodipine (n=13). Ultrasonic integrated backscatter (IBS) and serological markers of collagen type I synthesis and degradation were used to assess the degree of myocardial fibrosis just before and after 6 months of treatment. There were no significant differences in antihypertensive effects among the three agents. In the enalapril- and amlodipine-treated groups, the mean calibrated IBS values increased significantly after 6 months of treatment (enalapril: -31.6 +/- 1.3 to -29.4 +/- 1.2 dB, p=0.011; amlodipine: -30.6 +/- 1.4 to -27.2 +/- 1.2 dB, p=0.012). However, the mean calibrated IBS values in the losartan-treated group did not increase after 6 months of treatment (-31.2 +/- 1.7 to -31.3 +/- 1.4 dB, p=0.88). The ratio of the serum concentration of procollagen type I carboxy-terminal peptide to the serum concentration of collagen type I pyridinoline cross-linked carboxy-terminal telopeptide was significantly reduced in the losartan-treated group (42.6 +/- 4.6 to 34.4 +/- 3.6, p=0.038). The present study indicates that losartan more effectively suppresses myocardial fibrosis in patients with ESRD than does enalapril or amlodipine despite a comparable antihypertensive effect among the three drugs.

Relation of ultrasonic tissue characterization with integrated backscatter to contractile reserve in patients with chronic coronary artery disease

BACKGROUND

Previous studies have shown that viable but stunned myocardium displays contractile reserve and exhibits cardiac cycle-dependent variations of integrated backscatter (CVIB), whereas infarcted myocardium does not.

HYPOTHESIS

This study was designed to clarify whether assessment of the acoustic properties of the myocardium can predict contractile reserve in patients with chronic coronary artery disease (CAD).

METHODS

In all, 21 patients with chronic CAD and 19 normal control subjects were studied. The magnitude of CVIB of the myocardium was measured in the basal and mid segment of the anterior septum and posterior wall of the left ventricle, using a real-time, two-dimensional integrated backscatter imaging system. The results were compared with the percent systolic wall thickening and the wall motion before and after revascularization. The wall motion was graded as normal, hypokinetic, or akinetic, and contractile reserve was considered present when an akinetic or hypokinetic segment improved after revascularization.

RESULTS

The average magnitude of CVIB was lower among dysfunctional segments of CAD than among normal segments of controls (3.73 +/- 1.71 vs. 6.35 +/- 0.69, p < 0.001). Of the 77 segments examined, 38 showed reversible dysfunction. Before revascularization, percent systolic wall thickening was similar among segments showing contractile reserve compared with those with persistent dysfunction myocardium (17.97 +/- 8.41 vs. 16.83 +/- 6.37%, p = 0.19), and the mean CVIB was significantly greater in segments with than in those without contractile reserve (4.73 +/- 1.47 vs. 2.75 +/- 1.31, p < 0.001). The CVIB above 3 dB before percutaneous transluminal coronary angioplasty predicted segments with contractile reserve with a sensitivity and specificity of 84.2 and 79.5%, respectively.

CONCLUSIONS

Cardiac cycle-dependent variations of integrated backscatter reflected myocardial contractility and functional capacity of the myocardium. They predicted segmental contractile reserve in patients with CAD.

Ultrasonic tissue characterization for patients with Chagas' disease

This study was undertaken to test the hypothesis that ultrasonic tissue characterization, as evaluated by intensity and cardiac cyclic variation of integrated backscatter (IBS), could identify early myocardial involvement in Chagas' disease. We evaluated 69 participants, age 15 to 73 years (mean +/- SD: 49 +/- 12 years), who were divided as following: 19 control subjects; 13 patients with the indeterminate form of Chagas' disease; 7 patients with the digestive form; and 30 patients with the cardiac form. IBS images were obtained in parasternal short-axis (basal, papillary muscle, apical) view and analyzed in 12 left ventricular (LV) segments (anterior, lateral, posterior, and septal). The following IBS variables were evaluated: (1) the corrected coefficient (CC) of IBS, obtained by dividing IBS intensity, in each cardiac segment, by IBS intensity measured in a rubber phantom using the same equipment adjustments at the same depth; and (2) magnitude of cardiac cyclic variation (MCV) of IBS, as measured by the peak-to-peak difference between maximal and minimal values of IBS in cardiac cycle. The CC of IBS was increased (P <.05) for patients with the cardiac form who had LV segments with normal wall motion as compared with control subjects, in 4 of 12 segments evaluated (basal anterior, midposterior and midseptal, anterior apical), whereas the remaining chagasic groups were comparable with controls subjects. The CC of IBS tended to increase with worsening of LV segmental wall motion. MCV showed a large individual variability and had a large mean value (P <.05) in just 1 of 12 segments evaluated, when patients with the cardiac form were compared with control subjects. No correlation was observed between the magnitude of LV dysfunction and MCV of IBS.

IN CONCLUSION

(1) the CC of IBS was able to provide early differentiation of cardiac involvement for patients with Chagas' disease who had LV segments with normal wall motion; (2) increase of CC of IBS with worsening of LV segmental wall motion suggests a relationship between the acoustic properties of myocardial tissue and grading of myocardial fibrosis; (3) MCV was not able to differentiate patients with Chagas' disease from control subjects; and (4) patients with the indeterminate form of Chagas' disease were not differentiated from control subjects by any of the IBS techniques evaluated in this study.

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.

Resistance training and cardiac hypertrophy: unravelling the training effect

Resistance training (RT) is a popular method of conditioning to enhance sport performance as well as an effective form of exercise to attenuate the age-mediated decline in muscle strength and mass. Although the benefits of RT on skeletal muscle morphology and function are well established, its effect on left ventricular (LV) morphology remains equivocal. Some investigations have found that RT is associated with an obligatory increase in LV wall thickness and mass with minimal alteration in LV internal cavity dimension, an effect called concentric hypertrophy. However, others report that short- (<5 years) to long-term (>18 years) RT does not alter LV morphology, arguing that concentric hypertrophy is not an obligatory adaptation secondary to this form of exertion. This disparity between studies on whether RT consistently results in cardiac hypertrophy could be caused by: (i) acute cardiopulmonary mechanisms that minimise the increase in transmural pressure (i.e. ventricular pressure minus intrathoracic pressure) and LV wall stress during exercise; (ii) the underlying use of anabolic steroids by the athletes; or (iii) the specific type of RT performed. We propose that when LV geometry is altered after RT, the pattern is usually concentric hypertrophy in Olympic weightlifters. However, the pattern of eccentric hypertrophy (increased LV mass secondary to an increase in diastolic internal cavity dimension and wall thickness) is not uncommon in bodybuilders. Of particular interest, nearly 40% of all RT athletes have normal LV geometry, and these athletes are typically powerlifters. RT athletes who use anabolic steroids have been shown to have significantly higher LV mass compared with drug-free sport-matched athletes. This brief review will sort out some of the factors that may affect the acute and chronic outcome of RT on LV morphology. In addition, a conceptual framework is offered to help explain why cardiac hypertrophy is not always found in RT athletes.

Doppler tissue imaging: regional myocardial function in hypertrophic cardiomyopathy and in athlete's heart

BACKGROUND

The distinction between hypertrophic cardiomyopathy (HCM) and the athlete's (AT) heart is an important clinical problem, and the analysis of regional myocardial function with Doppler tissue imaging may be useful in the differential diagnosis.

OBJECTIVE

Our aim was to compare regional function assessed by Doppler tissue imaging in rowers and in a group of patients with HCM.

METHODS

In 24 patients with nonobstructive HCM and in 20 competitive rowers with similar age, blood pressure, and heart rate, we analyzed with pulsed Doppler tissue imaging left ventricular (LV) regional function (velocities, time intervals, heterogeneity and asynchrony indices, and meridional gradient) in the longitudinal (8 segments, apical views) and in the radial (2 segments, short-axis view) axis.

RESULTS

Compared with AT, patients with HCM showed: (1). systolic function; (a). longitudinal: lower velocities and meridional gradient; longer precontraction period (PCP); and higher PCP/LV contraction time; (b). radial: lower velocities and gradient; longer PCP; and higher PCP/LV contraction time; (2.diastolic function; (a). logitudinal: lower e (early diastolic), a (late diastolic), and e/a velocities; and longer prerelaxation time and time to peak e. The percentage of segments with e/a < 1 was 25% in the HCM group and 0% in the AT heart group; (b). radial: lower e velocity and gradient; lower e/a gradient; and longer medial prerelaxation and basal time to peak e. Most of these differences also occurred in the nonhypertrophied inferior wall of patients with HCM.

CONCLUSIONS

There are significant differences between regional LV function of competitive rowers and patients with HCM. These differences (1). occur in systole and diastole; (2). affect velocities and time intervals; (3). are more striking in the long axis, but are also seen in the short axis, and (4). also occur in nonhypertrophied segments, suggesting the usefulness of the technique in the differential diagnosis between the 2 situations, namely in individuals that fall in Maron's "grey zone."

Physiological effects of exercise on the cardiopulmonary system

The cardiopulmonary adaptations made to dynamic and static exercise show the amazing ability of the human body to alter physiological processes in order to meet metabolic demands. A remarkable partnership that allows individuals to maximize their abilities and obtain goals exists between the cardiovascular and pulmonary systems. The adaptations of the cardiopulmonary system depend heavily on the intensity, duration, frequency, and type of exercise being performed. Although most of this article examined dynamic and static exercise separately, the majority of individuals train using a combination of these two modes. The overall adaptations will vary with the chosen degree of each exercise mode. An appropriate exercise program allows for improvements in the cardiopulmonary system that help develop and maintain fitness levels.

Differentiation between pathologic and physiologic left ventricular hypertrophy by tissue Doppler assessment of long-axis function in patients with hypertrophic cardiomyopathy or systemic hypertension and in athletes

To identify new echocardiographic indexes of long-axis function that might differentiate between pathologic and physiologic left ventricular (LV) hypertrophy, we compared 60 subjects with different types of LV hypertrophy (group I: 15 patients with hypertrophic cardiomyopathy, group II: 15 patients with systemic hypertension, and group III: 30 athletes) with 20 normal subjects (group IV). The peak velocities of mitral annular motion at 4 sites were measured from the apex by tissue Doppler echocardiography. There were no differences in mean age and global ejection fraction between groups. Groups I and II had lower long-axis systolic and early diastolic velocities than the athletes (p <0.01) for all 4 sites. The best differentiation of pathologic from physiologic hypertrophy was provided by a mean systolic annular velocity <9 cm/s (sensitivity 87%, specificity 97%). Heterogeneity of annular velocities discriminated between group I and group II. Thus, long-axis systolic and early diastolic velocities are decreased in patients with pathologic hypertrophy, but preserved in athletes. These simple new echocardiographic parameters can differentiate between pathologic and physiologic hypertrophy.

Cyclic variation of the myocardial integrated backscatter signal in hypertensive cardiopathy: a preliminary study

BACKGROUND

Ultrasound tissue characterization studies realized through integrated backscatter analysis with end-diastolic sampling in hypertensive cardiopathy have demonstrated that abnormalities in the left ventricular myocardial ultrasonic texture are present in extreme forms of left ventricular hypertrophy (LVH). Such abnormalities are not evident in the athlete's heart. The aim of the present study was to analyze the ultrasonic backscatter myocardial indexes both as peak end-diastolic signal intensity and as cardiac-cyclic variation in two models of LVH: hypertensive cardiopathy and athlete's heart.

METHODS

Three groups of 10 subjects each, all men of mean age (31.6+/-3.5 years), and of comparable weight and height, were analyzed. Group A comprised 10 cyclists of good professional level, while hypertensive patients were grouped in Group H. Both groups presented a comparable left ventricular mass (LVM). Group C included 10 healthy subjects acting as controls. The men with hypertension were selected on the basis of the results of ambulatory monitoring of the blood pressure according to ISH-World Health Organization guidelines (International Society of Hypertension). A 2D-color Doppler echocardiography with a digital echograph Sonos 5500 (Agilent Technologies, Andover, Massachusetts, USA), was carried out on all the subjects in the study for conventional analysis of the LVM and function. The ultrasonic myocardial integrated backscatter signal (IBS) was analyzed with an 'acoustic densitometry' module implemented on a AT echograph. The signal was also sampled with a region of interest (ROI) placed at interventricular septum and at posterior left ventricular wall level. The systo-diastolic variation of the backscatter was also considered, as cyclic variation index (CVIibs).

RESULTS

According to the inclusion criteria, the LVM was comparable in groups A and H, but it was significantly higher than group C (left ventricular mass (body surface) (LVMbs)=154.5+/-18.7 (A), 146.8+/-25.5 (H), 101.4+/-12.4 (C), p < 0.001). The end-diastolic IBS did not show significant statistical differences among the three groups. The CVI(IBS) both at septum (30.5+/-5.3 (A), 13.2+/-13.1 (H), 27.2+/-7.3(C), p < 0.002) and posterior wall level (43.7+/-9.1 (A), 16.5+/-12.1 (H), 40.7+/-9.1 (C), p < 0.001) though, was significantly lower in the hypertensive patients than in both the athletes and the control group, where the results were comparable.

CONCLUSION

A significant alteration of the myocardial CVIibs (both for septum and posterior wall) was found in the hypertensive model. This was probably the expression of an alteration in the intramural myocardial function.

Transmural heterogeneity of myocardial integrated backscatter in diabetic patients without overt cardiac disease

It is important to detect early changes in diabetic myocardium, because some diabetic patients suffer from diabetic cardiomyopathy, especially those with poorer glycemic control or hypertension (HT). To clarify whether ultrasonic tissue characterization can noninvasively detect ultrastructural changes in diabetic myocardium, we analyzed the transmural heterogeneity in myocardial integrated backscatter (THIB) in 20 diabetic patients and 16 normal subjects. THIB was defined as the absolute value of difference of integrated backscatter between the endocardial and epicardial half of the myocardium. THIB in diabetic patients was significantly greater than that in normal subjects. In diabetic patients, there was a significant correlation between glycosylated hemoglobin and THIB, and the greater THIB was shown in patients with HT compared with those without HT. Early changes in the myocardium, related to increased interstitial collagen deposition or other occult cardiomyopathic changes, may be detected on the basis of quantitative analysis of THIB in diabetic patients.

Prevention of doxorubicin (adriamycin)-induced cardiomyopathy by simultaneous administration of angiotensin-converting enzyme inhibitor assessed by acoustic densitometry

The purpose of our study has to determine the myocardial protective effects of the angiotensin-converting enzyme (ACE) inhibitor temocapril (TEM, 7 mg/kg/day) simultaneously administered with doxorubicin (Adriamycin). Twenty male Sprague-Dawley rats were intraperitoneally administered a cumulative dose of 15 mg/kg of doxorubicin (each dose of 1.0 mg/kg x 15) for 3 weeks, and divided into TEM-untreated and -treated rats. Seven control rats were injected with saline intraperitoneally. Body weight, hemodynamics, and echocardiographic measurements including quantitative analysis of ultrasonic integrated backscatter (IB) were obtained for 12 weeks after treatment. Finally, rats were killed for histopathologic study. At 6 weeks, end-diastolic left ventricular diameter (LVD) and percentage fractional shortening (%FS) were similar in TEM-treated and TEM-untreated rats, but cyclic variation of IB (dB) significantly decreased in TEM-untreated rats (7.3 +/- 1.2; control rats, 9.7 +/- 0.9; p < 0.01). At 12 weeks, %FS decreased in TEM-untreated rats (26.1 +/- 6.1%: TEM-treated rats, 34.2 +/- 6.2; p < 0.05), and calibrated IB (dB) in TEM-untreated rats (15.5 +/- 0.5) increased as compared with that in TEM-treated rats (12.1 +/- 0.7; p < 0.01). Interstitial collagen accumulation increased in TEM-untreated rats and was inhibited in treated rats. Simultaneous administration of TEM with doxorubicin was beneficial in preventing doxorubicin-induced myocardial damage, and myocardial tissue characterization was useful for the early detection of myocardial damage and the assessment of therapy.

Sensitive detection of myocardial contraction abnormality in chronic hemodialysis patients by ultrasonic tissue characterization with integrated backscatter

Since acoustic properties of the myocardium are sensitive to the myocardial structure and the contractile conditions of myocyte, the authors evaluated cardiac dysfunction based on the integrated ultrasonic backscatter in 18 hemodialysis (HD) patients (duration: 102 +/- 84 months, mean age: 57.6 +/- 9.7 years) and 11 age-matched normals. The cyclic variation of integrated backscatter (CV-IB) at interventricular septum (IVS) and left ventricular posterior wall (PW) was measured and compared with percent fractional shortening (%FS) and percent wall thickening (%Th). The CV-IB of HD patients was smaller than that of control subjects (IVS: 6.2 +/- 1.1 dB vs 8.2 +/- 1.1 dB, p = 0.0003 and PW: 8.4 +/- 2.2 vs 10.3 +/- 1.3, p= 0.025). No significant difference was observed in %FS and %Th between HD patients and control subjects. In HD, the ratio of velocities of early diastolic inflow (E) to late atrial inflow was decreased (0.7 +/- 0.2 vs 1.1 +/- 0.7, p = 0.049) and deceleration time of E was prolonged significantly (200 +/- 28 msec vs 159 +/- 30 msec, p = 0.0082). In the absence of overt cardiac systolic dysfunction, myocardial damage indicated as a decrease in CV-IB and diastolic dysfunction identified on transmitral velocity waveform were detected, which may reflect from the myocardial fibrosis. As a mechanism, pressure overload, hyperparathyroidism, and anemia were neglected, and the other humoral factors may contribute to the myocardial damage in chronic renal failure.

Left ventricular morphology in elite female resistance-trained athletes

Long-term resistance training as performed by elite female resistance-trained athletes appears to be an insufficient stimulus to alter left ventricular cavity size, wall thickness, or estimated mass.

The morphologic consequences of systemic training

The development of echocardiography in the 1970s led to the flourishing of the study of the athlete's heart. From the earliest studies, it was apparent that athletes develop enlargement of the left ventricular cavity and thickening of myocardium in response to prolonged repetitive training. The changes in echocardiographic measurements are small and often within quoted normal ranges. By comparison to sedentary controls, however, left ventricular end-diastolic dimension is increased by approximately 10%, posterior wall dimension by 15% to 20%, and calculated mass by up to 45%.

Outer limits of the athlete's heart, the effect of gender, and relevance to the differential diagnosis with primary cardiac diseases

Two concepts from pathologic descriptions of myocardial hypertrophy in trained individuals merit consideration: (1) The heart of the trained athlete can be twice the normal size, but histologic structure remains intact, and (2) the weight of the trained heart does not usually surpass the limit of 500 g, defined as the critical heart weight. Even though this threshold cannot be accepted dogmatically, the concept of an upper limit for physiologic cardiac remodeling is nevertheless relevant to the clinical question of distinguishing extreme expressions of athlete's heart from primary pathologic conditions. This morphologic distinction depends on whether the magnitude of cardiac remodeling in athletes exceeds that expected as a result of athletic conditioning alone. There has also been a great interest in understanding the impact that types of athletic conditioning and gender have on defining the upper limits to which such physiologic hypertrophy may extend.

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.

Ultrasonic tissue characterization of infarcted myocardium by scanning acoustic microscopy

The purpose of this study was to ultrasonically characterize infarcted human myocardial tissue at the microscopic level by scanning acoustic microscopy. Infarcted myocardial specimens from ten cases with acute myocardial infarction were studied. Specimens were formalin fixed, paraffin embedded and sectioned to 10-micron thickness. A specially developed scanning acoustic microscope system, operating in the 100- to 200-MHz ultrasound frequency range, was used for the measurements. The values of the attenuation constant were 0.94 +/- 0.04 dB/mm/MHz in normal myocardium, 0.71 +/- 0.12 dB/mm/MHz in degenerated myocardium, 0.88 +/- 0.47 dB/mm/MHz in granulation tissue and 1.75 +/- 0.11 dB/mm/MHz in fibrosis. The values of sound speed were 1620.2 +/- 8.2 m/s in normal myocardium, 1572.4 +/- 10.6 m/s in degenerated myocardium, 1590.2 +/- 32.5 m/s in granulation tissue and 1690.3 +/- 9.1 m/s in fibrosis. The ultrasonic properties of the diseased myocardium at the microscopic level will provide important information for ultrasonic tissue characterization at the macroscopic level.

Myocardial ultrasonic tissue characterization in patients with different types of left ventricular hypertrophy: a videodensitometric approach

Although analysis of the radio frequency signal is the most accurate approach to myocardial tissue characterization, clinical diffusion has been limited because of the complex technology required. Much easier to perform, videodensitometric analysis could represent a valuable alternative. Previous works carried out on radio frequency data have shown that the absolute value of ultrasonic back scatter increases while its diastole-to-systole variation decreases in the hypertrophied myocardium. This study was aimed at clarifying whether alterations in characterization indexes of ultrasonic tissue can be detected by means of a videodensitometric approach, whether a specific type of left ventricular (LV) hypertrophy can be identified with this method, and finally what possible relationships exist between parameters of contractile function and tissue characterization indexes. Myocardial echo intensity (MEI), its cyclic variation (CV), and the dynamic relationship between myocardial signal and wall thickness variations during the cardiac cycle were assessed in 20 healthy subjects, 11 patients with essential hypertension and LV hypertrophy, 15 patients with hypertrophic cardiomyopathy, and 4 patients with primary amyloidosis. The CV was lower in the interventricular septum of patients with cardiac hypertrophy as a group, compared with that of control subjects (13.0% +/- 5.6% versus 18.8% +/- 5.5%, p < 0.001), but it was similar among patients with different types of hypertrophy. In control subjects, a significant inverse correlation was found between the progressive decrease of the myocardial signal and the parallel increase in wall thickness during systole; this correlation was lost in 60% of patients with hypertrophic cardiomyopathy and 50% of those with amyloidosis, but only in 9% of patients with essential hypertension (chi square analysis 12.68, p < 0.01). The CV was associated with systolic wall thickening (r = 0.53, p = 0.0001) and fractional shortening (r = 0.44, p = 0.0014). MEI and its CV per se cannot distinguish among different types of LV hypertrophy; however, the loss of an inverse relationship between the myocardial signal and wall thickness may suggest abnormal myocardial conditions in individual patients with the same disease or comparable wall thickness.

A model of ultrasound backscatter for the assessment of myocardial tissue structure and architecture

A statistical parametric model of returning echoes from myocardium is theorized in order to investigate the relationship between normal myocardium structure and spectral signatures with the use of ultrasonic tissue characterization. It is hypothesized, that in a clinical setting the normal myofiber architecture in the left ventricular wall is structured as a matrix of cylinder scatterers whose orientation and spatial distribution vary according to two different statistical distribution laws: 1) a Gaussian law to approximate parametric angular myofiber variability at each site within the myocardial wall; 2) a gamma distribution law to describe parametric regularity in scatterer interdistance. In the model, the effect of the angle of insonification with respect to the alignment of myofibers on ultrasound backscatter was considered. The slope of the power spectral density (PSD) evaluated within the echocardiographic transducer bandwidth has been used as a ultrasonic tissue characterization parameter. The model has been tested by computer simulation and in vitro measurements on myocardial pig tissue specimens. The concordance between experimental and simulated results confirms that the model accounts for the process underlying the echo formation from normal myocardium. Moreover, it provides a simple method of simulation which can be easily implemented and used for the assessment of pathologic alterations.

Dobutamine stress ultrasonic myocardial tissue characterization in patients with dilated cardiomyopathy

Although acoustic properties of the myocardium are different between patients with cardiomyopathy and normal subjects, the frequency of the abnormal properties in patients with cardiomyopathy is unknown. We assessed the frequency of abnormal acoustic properties of the myocardium detectable with integrated backscatter in patients with cardiomyopathy and attempted more sensitive ultrasonic tissue characterization by combining dobutamine stress testing in patients with cardiomyopathy with apparently normal acoustic properties of the myocardium at rest. The magnitude of cyclic variation of integrated backscatter and calibrated myocardial integrated backscatter at end diastole were measured in 36 normal subjects and 40 patients with dilated cardiomyopathy. Either one of the integrated backscatter parameters was abnormal in 30 of 40 patients with cardiomyopathy. Dobutamine stress ultrasonic tissue characterization was performed in 10 patients with cardiomyopathy with normal values of both integrated backscatter parameters and 10 normal subjects. Calibrated myocardial integrated backscatter did not change during dobutamine infusion in any subject. The magnitude of cyclic variation in integrated backscatter increased in normal subjects but did not change in patients with cardiomyopathy despite a comparative associated increase in the systolic wall thickening during dobutamine infusion. Abnormal acoustic properties are detectable at rest with myocardial integrated backscatter about in three quarters of patients with cardiomyopathy. A combination of dobutamine stress testing would provide more sensitive ultrasonic myocardial tissue characterization and may make it possible to detect subtle changes in the acoustic properties of the myocardium in patients with dilated cardiomyopathy. Therefore dobutamine stress ultrasonic tissue characterization may detect mild dilated cardiomyopathy.

Myocardial integrated ultrasonic backscatter in patients with old myocardial infarction: comparison with radionuclide evaluation

The purpose of our study was to clarify whether the abnormalities in integrated backscatter may be used to assess myocardial viability in patients with old myocardial infarction by comparing these integrated backscatter parameters with conventional radionuclide and echocardiographic estimates of myocardial viability. Two myocardial integrated backscatter parameters, the magnitude of cyclic variation in integrated backscatter and the myocardial integrated backscatter calibrated with the power of Doppler signals from the blood along the same ultrasound beam (calibrated myocardial integrated backscatter), were measured in 21 normal persons and 33 patients with old anteroseptal myocardial infarction. Calibrated myocardial integrated backscatter was higher and the magnitude of cyclic variation in integrated backscatter was lower in the infarct septum compared with the septum of normal subjects. Percent thallium uptake, as assessed in scintigraphic images taken at rest or after reinjection, correlated well with the calibrated myocardial integrated backscatter (r = -0.72, p < 0.01) and more weakly but significantly with the magnitude of cyclic variation in integrated backscatter (r = 0.55, p < 0.05) in 16 of 33 patients. The measurement of calibrated myocardial integrated backscatter, in addition to the magnitude of cyclic variation of integrated backscatter, may likely be valuable in the noninvasive assessment of myocardial viability.

Dissociation between wall thickening of normal myocardium and cyclic variation of backscatter during inotropic stimulation

The purpose of this study was to determine the relation between increased myocardial wall thickening during inotropic stimulation and quantitative acoustic properties of normal myocardium in humans. We first validated a new 2-dimensional ultrasonic backscatter imaging approach for measurement of cyclic variation in the parasternal long-axis view against conventional M-mode integrated backscatter technique in 41 patients and controls (group A). We then performed 2-dimensional ultrasonic integrated backscatter imaging in 18 patients (group B) with normal segmental function at baseline to determine the magnitude of the cyclic variation of the septum and the posterior wall before and during infusion of dobutamine (10 and 20 microgram/kg/min). Group A patients showed a close correlation of the cyclic variation obtained by the new 2-dimensional ultrasonic integrated backscatter imaging approach and the conventional M-mode technique. Group B patients had mean values of cyclic variation that remained unchanged in the septum (4.4 +/- 1.4, 4.3 +/- 1.7, and 4.8 +/- 1.6 dB at baseline and at each dobutamine stage, respectively, p = NS) and in the posterior wall (6.4 +/- 1.7, 6.4 +/- 1.8 and 6.1 +/- 1.9 dB, respectively, p = NS) despite progressive dobutamine-induced increases in percent wall thickening (septum: 38 +/- 10% to 57 +/- 17% and 68 +/- 19%, respectively, and posterior wall 42 +/- 13% to 72 +/- 20% and 77 +/- 18%, respectively; both p <0.001 vs baseline for both walls). Thus, physical properties of normal myocardium remain unchanged during inotropic stimulation.

Left ventricular function during exercise in athletes and in sedentary men

Aim of this study was to evaluate left ventricular function during exercise in 10 male elite runners and in 10 sedentary males. End-diastolic (EDV) and end-systolic volume (ESV), left ventricular ejection fraction (EF), early peak transmitral flow velocity (peak E), time-velocity integral of mitral inflow (m-TVI); mitral cross sectional area (m-CSA); mitral stroke volume (SV), and cardiac output (CO) were measured by echo-Doppler. We simultaneously analyzed: VO2max by spirometric method, mean arterial blood pressure (MAP) by sphygmomanometer, and heart rate (HR) by ECG. The parameters were measured under basal conditions (level 1), at 50% of maximal aerobic capacity (level 2), at peak of exercise (level 3) and during recovery. Ejection fraction in athletes increased significantly at peak of exercise through Frank-Starling mechanism. Stroke volume and cardiac output increased significantly in athletes at peak of exercise. Left ventricular diastolic function was superior in athletes versus controls: in fact, higher peak E in athletes enhanced early diastolic ventricular filling. Therefore, the athletes showed complex cardiovascular adjustments induced by training, which allowed an higher peak working power, a greater cardiac output, and VO2max when compared with an untrained control population.

Quantitative Texture Analysis in Two-Dimensional Echocardiography: Application to the Diagnosis of Myocardial Hemochromatosis

BACKGROUND: Myocardial reflectivity is abnormally increased in patients with thalassemia major under transfusion treatment, probably due to myocardial iron deposits and/or secondary structural changes. Such increased reflectivity has been detected by both qualitative and subjective analysis of two-dimensional echocardiographic (2-D echo) images and quantitative assessment of integrated backscatter amplitude with noncommercially available ultrasound prototypes. The purpose of this study was to assess the acoustic properties of myocardium in patients with beta-thalassemia major and iron overload by means of quantitative computerized offline textural analysis of conventionally recorded 2-D echo images, and to compare textural data with other qualitative (visual assessment) and quantitative (ultrasound backscatter analysis) approaches for myocardial ultrasound tissue characterization simultaneously applied to these patients. METHODS AND RESULTS: Thirty-five young patients with thalassemia major, without clinical signs of cardiac failure, and 20 age and sex matched normal controls were studied by echocardiography. Each patient was receiving blood transfusion every 2-3 weeks. Two-dimensional echo images, obtained with a commercially available echocardiograph using the parasternal long-axis view, were digitized off line and analyzed by first and second order texture algorithms applied to regions of interest in the myocardium (septal and posterior wall). The mean gray level value was higher in thalassemic patients than in controls on both the septum (110 +/- 25 vs 57 +/- 13, arbitrary units on a 0-255 scale; P < 0.01) and posterior wall (91 +/- 25 vs 67 +/- 18; P < 0.01). Among second order statistical parameters, contrast and angular second moment significantly (P < 0.01) differentiated septal and posterior walls of patients and controls. In thalassemic patients, no consistent correlation was found between wall texture parameters and hematologic (years of transfusions and chelation, number of transfusions), 2-D echo (posterior wall thickness, left ventricular end-diastolic diameter), and Doppler (transmitral E/A waves ratio) parameters. Myocardial walls with visually assessed increased echo reflectivity showed a trend toward higher values of mean gray level when compared with myocardial segments with qualitatively assessed normal reflectivity (septum: 121 +/- 26 vs 106 +/- 24; posterior wall: 105 +/- 23 vs 87 +/- 23). Although radiofrequency integrated backscatter has been demonstrated to be capable of identifying thalassemic patients, no significant correlation was found between mean gray level (by texture analysis) and radiofrequency data (septum: r = 0.03; posterior wall: r = 0.09; P = NS for both). CONCLUSIONS: Myocardial walls affected by hemochromatosis show ultrasound image texture alterations that may be quantified with digital image analysis techniques and appear mostly unrelated to hematologic and conventional, as well as radiofrequency-based, echocardiographic parameters. These changes in quantitatively evaluated echo reflectivity are present even before the development of clinical and echocardiographic signs of cardiac dysfunction. (ECHOCARDIOGRAPHY, Volume 13, January 1996)

Analysis of transmural trend of myocardial integrated ultrasonic backscatter in patients with old myocardial infarction

Changes in myocardial integrated backscatter (IB) reflect myocardial viability in patients with myocardial infarction. IB may be obtained separately in the subendocardial and subepicardial layers to establish a transmural trend. The purpose of this study is to examine the possibilities that the measurement of the transmural trend in myocardial IB may provide a new estimate of transmurality of infarction in patients with old myocardial infarction. A calibrated myocardial IB and its transmural trend were measured both in the septum and posterior wall in 21 normal subjects, 24 patients with anteroseptal old myocardial infarction (13 patients with Q-wave myocardial infarction and 11 patients with non-Q-wave myocardial infarction). The transmural trend in myocardial IB was assessed by measuring the acoustic parameter separately in the right and left ventricular halves of the septum, and in the endocardial and epicardial halves of the posterior wall. The magnitude of cyclic variation of IB (a difference between minimum and maximum peaks) was lower, and calibrated myocardial IB (the maximum value of myocardial IB at end diastole calibrated with the power of Doppler signals from the blood along the same ultrasound beam) was higher in patients with anteroseptal old myocardial infarction in the septum, compared with normal subjects. Among patients with myocardial infarction, the difference in these IB parameters between the right and left ventricular halves of the septum was found only in patients with non-Q-wave myocardial infarction. The transmural trend of myocardial IB was likely to reflect the transmurality of myocardial infarction. Therefore, our data give another insight into the assessment of transmural inhomogeneity of myocardial fibrosis or viability in patients with myocardial infarction.

Influence of preload, afterload, and contractility on myocardial ultrasonic tissue characterization with integrated backscatter

Influence of hemodynamic changes in preload, afterload and contractility on myocardial integrated backscatter (IB) was studied in 26 adult mongrel dogs by measuring myocardial IB calibrated with the backscatter from the blood during volume infusion (preload alteration), during aortic constriction (afterload alteration), and during dobutamine or propranolol infusion (contractility alteration). Changes in preload, afterload or contractility did not significantly affect the calibrated myocardial IB either in the septum or in the posterior wall. Changes in preload and afterload did not affect the magnitude of cyclic variation in IB. However, dobutamine produced a significant increase in the magnitude of cyclic variation in IB and propranolol significantly decreased the magnitude of cyclic variation in IB. These data indicated that the calibrated myocardial IB is independent of preload, afterload and contractility, and that the magnitude of cyclic variation in IB is influenced by contractility. We may estimate static (related to histological changes such as fibrosis, edema, necrosis, and so on) and dynamic (related to myocardial contraction such as sarcomere length, muscle fiber orientation, and so on) properties of the myocardium more precisely using myocardial IB calibrated with the backscatter from the blood in addition to the magnitude of cyclic variation in IB.

Validation of transthoracic myocardial ultrasonic tissue characterization: comparison of transthoracic and open-chest measurements of integrated backscatter

To investigate whether myocardial integrated backscatter (IB) can be measured through the chest wall, myocardial IB parameters were measured in five adult mongrel dogs with a newly developed IB imaging system capable of measurements of myocardial IB relative to backscatter from the blood. There was no significant difference in the calibrated myocardial IB between the closed chest and the open chest conditions either in the septum or in the posterior wall if a 2.5- or 3.5-MHz frequency transducer was used. There was no significant difference in the magnitude of cyclic variation in IB between the closed chest and the open chest conditions independent of the frequency of the transducer used. These data suggest that we can accurately measure not only the magnitude of cyclic variation in IB but also the calibrated myocardial IB through the chest wall with a 2.5- or 3.5-MHz frequency transducer. Such data may validate measurements of myocardial IB parameters through the chest wall even in humans.

When can Doppler be used in place of integrated backscatter as a measure of scattered ultrasound intensity?

The purpose of this work was to determine under what circumstances the intensity of Doppler audio signals can be used as a substitute for the more direct and complex measure of ultrasonic backscatter (integrated backscatter) which requires radio-frequency ultrasound signals. Using a rotating rubber disk phantom and a microbubble echo-contrast flow phantom, we have shown that the intensity of audio Doppler signals is independent of the constraints typically associated with Doppler ultrasound (velocity and angle), but like integrated backscatter depends on the transmit intensity, gain of the ultrasound receiver, attenuation and the nature of the scatterers. Using Doppler ultrasound for backscatter measurements is ideally suited for the expected application of the technique: the assessment of echo contrast in cardiac chambers, blood vessels and tissue perfusion (i.e., any flow system). Compared to integrated backscatter, the Doppler audio method has the advantage of using standard clinical ultrasound machines, requires less sophisticated data storage and processing equipment and the positioning system for the region of interest (the Doppler sample volume) is built into all pulsed-wave Doppler machines. Further, the low-velocity filter removes all nonmoving scatterers (like the intense echoes from heart valves and the walls of blood vessels), thus allowing study of only those echoes originating from the blood pool. This combination of features is what attracted us to the Doppler method for quantitating ultrasonic backscatter in flow systems.

Analysis of transmural trend of myocardial integrated ultrasound backscatter for differentiation of hypertrophic cardiomyopathy and ventricular hypertrophy due to hypertension

OBJECTIVES

This study was undertaken to differentiate hypertrophic cardiomyopathy from hypertensive hypertrophy using a newly developed M-mode format integrated backscatter imaging system capable of calibrating myocardial integrated backscatter with the power of Doppler signals from the blood.

BACKGROUND

Myocardial integrated ultrasound backscatter changes in patients with hypertrophic cardiomyopathy; however, it is unknown whether ultrasound myocardial tissue characterization may be useful in differentiating hypertrophic cardiomyopathy from hypertensive hypertrophy.

METHODS

Calibrated myocardial integrated backscatter and its transmural gradient were measured in the septum and posterior wall in 31 normal subjects, 13 patients with hypertensive hypertrophy and 22 patients with hypertrophic cardiomyopathy. The gradient in integrated backscatter was determined as the ratio of calibrated integrated backscatter in the endocardial half to that in the epicardial half of the myocardium.

RESULTS

Cyclic variation of integrated backscatter was smaller and calibrated myocardial integrated backscatter higher in patients with hypertrophied hearts than in normal subjects, but there were no significant differences in either integrated backscatter measure between patients with hypertensive hypertrophy and those with hypertrophic cardiomyopathy. Transmural gradient in myocardial integrated backscatter was present only in patients with hypertrophic cardiomyopathy (5.0 +/- 1.8 dB [mean +/- SD] for the septum; 1.2 +/- 1.6 dB for the posterior wall).

CONCLUSIONS

Hypertrophic cardiomyopathy and ventricular hypertrophy due to hypertension can be differentiated on the basis of quantitative analysis of the transmural gradient in integrated backscatter.

Acquisition and processing of the radio-frequency signal in echocardiography: a new global approach

Recently there has been an increasing interest in the use of the "raw" radio-frequency (RF) signal generated in echocardiography for use in tissue-characterization to distinguish between normal and pathological myocardium, for automatic delineation of the endocardial border without being limited by the weak contrast of the traditional video images, and for use in contrast echography, where it could offer the possibility to visualize perfusion using intravenous contrast injections. One of the main problems in this kind of research is the acquisition of the signal having a high frequency and large bandwidth. We have developed a new global method for the acquisition of this RF signal. To digitize the data, a video sequencer is used. In this way it becomes possible to sample all available data generated by the echographic equipment during at least 1 s. This means that all data of the complete sector scan during a complete heart-cycle can be digitized without using any data reduction technique or triggering on the electrocardiogram. The advantage of this approach is that all characteristics of the signal can be studied, without being limited by data reduction techniques used during acquisition. This method enables us to calculate parameters such as "integrated backscatter," or to investigate the signal more extensively, e.g., by using spectrum analysis. We can compare different regions of the myocardium and examine them during the heart-cycle, all within the same beat. We have also written a software package for the processing of the large amount of data resulting from the acquisition.

Reduction in left ventricular wall thickness after deconditioning in highly trained Olympic athletes

BACKGROUND

Clinical distinction between athlete's heart and hypertrophic cardiomyopathy in a trained athlete is often difficult. In an effort to identify variables that may aid in this differential diagnosis, the effects of deconditioning on left ventricular wall thickness were assessed in six highly trained elite athletes who had competed in rowing or canoeing at the 1988 Seoul Olympic Games. Each of these athletes showed substantial ventricular septal thickening associated with training (13-15 mm) which resembled that of hypertrophic cardiomyopathy.

METHODS

The athletes voluntarily reduced their training substantially for 6-34 weeks (mean 13) after the Olympic competition. Echocardiography was performed at peak training and also after deconditioning, and cardiac dimensions were assessed blindly.

RESULTS

Maximum ventricular septal thickness was 13.8 (0.9) mm in the trained state and 10.5 (0.5) in the deconditioned state (p < 0.005) (change 15-33%).

CONCLUSIONS

The finding that deconditioning may be associated with a considerable reduction in ventricular septal thickness in elite athletes over short periods strongly suggests that these athletes had a physiological form of left ventricular hypertrophy induced by training. Such a reduction in wall thickness with deconditioning may help to distinguish between the physiological hypertrophy of athlete's heart and primary pathological hypertrophy (for example, hypertrophic cardiomyopathy) in selected athletes with increased left ventricular wall thickness.