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

Childhood Hypertrophic Cardiomyopathy: A Disease of the Cardiac Sarcomere

Hypertrophic cardiomyopathy is the second most common cause of cardiomyopathy presenting during childhood and whilst its underlying aetiology is variable, the majority of disease is caused by sarcomeric protein gene variants. Sarcomeric disease can present at any age with highly variable disease phenotype, progression and outcomes. The majority have good childhood-outcomes with reported 5-year survival rates above 80%. However, childhood onset disease is associated with considerable life-long morbidity and mortality, including a higher SCD rate during childhood than seen in adults. Management is currently focused on relieving symptoms and preventing disease-related complications, but the possibility of future disease-modifying therapies offers an exciting opportunity to modulate disease expression and outcomes in these young patients.

Characteristic systolic waveform of left ventricular longitudinal strain rate in patients with hypertrophic cardiomyopathy

We analyzed the waveform of systolic strain and strain-rate curves to find a characteristic left ventricular (LV) myocardial contraction pattern in patients with hypertrophic cardiomyopathy (HCM), and evaluated the utility of these parameters for the differentiation of HCM and LV hypertrophy secondary to hypertension (HT). From global strain and strain-rate curves in the longitudinal and circumferential directions, the time from mitral valve closure to the peak strains (T-LS and T-CS, respectively) and the peak systolic strain rates (T-LSSR and T-CSSR, respectively) were measured in 34 patients with HCM, 30 patients with HT, and 25 control subjects. The systolic strain-rate waveform was classified into 3 patterns ("V", "W", and "√" pattern). In the HCM group, T-LS was prolonged, but T-LSSR was shortened; consequently, T-LSSR/T-LS ratio was distinctly lower than in the HT and control groups. The "√" pattern of longitudinal strain-rate waveform was more frequently seen in the HCM group (74 %) than in the control (4 %) and HT (20 %) groups. Similar but less distinct results were obtained in the circumferential direction. To differentiate HCM from HT, the sensitivity and specificity of the T-LSSR/T-LS ratio <0.34 and the "√"-shaped longitudinal strain-rate waveform were 85 and 63 %, and 74 and 80 %, respectively. In conclusion, in patients with HCM, a reduced T-LSSR/T-LS ratio and a characteristic "√"-shaped waveform of LV systolic strain rate was seen, especially in the longitudinal direction. The timing and waveform analyses of systolic strain rate may be useful to distinguish between HCM and HT.

Assessment of left ventricular radial deformation by speckle tracking imaging

The left ventricular radial strain in the inner and outer layers was evaluated by using two-dimensional speckle tracking imaging (2DS). Twenty-five piglets were studied. The short axis views were acquired. Peak systolic radial strain was measured from 6 circumferential points related to 6 standard segments in the inner and outer layers respectively using 2DS methods. The peak positive first derivative (dp/dt) of left ventricular pressure was compared to the radial strain from 2DS. The inner band showed higher peak radial strain values as compared to the outer band at all of the segments (P<0.0001), but the differences had significance just in anteroseptal, posterior, inferior and septal segments (P<0.05). Good correlation could be found between radial strain of inner and outer layers and peak dp/dt (P<0.001). These preliminary results showed that the degree of local deformation or wall thickening of the ventricular wall in its inner layer was more obvious than its outer layer. It is suggested that the 2DS technique is useful and sensitive for better understanding the regional and global myocardial motion and its relationship to the complex architecture of myocardium.

Impaired myocardial function in hypertrophic cardiomyopathy

BACKGROUND

Tissue Doppler imaging (TDI) parameters of peak myocardial velocities (S', E', and A') has been employed to assess the regional left ventricular myocardial function. The global function index (GFI) derived from TDI has been recently employed to distinguish the different etiologies of left ventricular hypertrophy.

OBJECTIVE

To analyze whether the GFI or individual TDI parameters of peak myocardial velocities (S', E', and A') allows detecting different degrees of regional myocardial dysfunction in the most frequent forms of hypertrophic cardiomyopathy (HCM).

METHODS

GFI = (E/E')/S' (where E is the peak transmitral flow velocity, E' is the early diastolic myocardial velocity, and S' is the peak systolic myocardial velocity) and TDI peak myocardial velocities was measured in the septal and lateral mitral annulus in 101 patients with HCM (mean age 47.5 +/- 14 years, 58 women) and in age-matched group of 30 healthy controls (mean age 46 +/- 6 years, 16 women).

RESULTS

Forty-five patients had nonobstructive asymmetric septal HCM, 20 patients had a subaortic gradient >or= 30 mm Hg, 21 p. had apical HCM, and 15 p. had other forms of HCM (midventricular, symmetric, and biventricular). All patients with HCM exhibited a decrease in early diastolic (E') and systolic (S') myocardial velocities, both in the lateral and septal-mitral annulus border, but more pronounced in septal-mitral annulus. Septal GFI was higher in HCM patients than in healthy subjects (1.8 (1.1-2.5) and (0.57 (0.31-0.92), respectively, P < 0.001), but no differences were seen when different forms of HCM were compared.

CONCLUSIONS

In a selected population of patients with HCM and a preserved left ventricular(LV) systolic function, GFI and individual TDI parameters of peak velocity (S', E', and A') and E/E' ratio were similar in different forms of HCM, indicating that in all patients with HCM there is regional systolic and diastolic myocardial dysfunction, regardless of the location of hypertrophy.

Relationship between outflow obstruction and left ventricular functional impairment in hypertrophic cardiomyopathy: a Doppler echocardiographic study

Left ventricular outflow tract (LVOT) obstruction is predictive of a worse outcome in hypertrophic cardiomyopathy (HCM). In a detailed Doppler echocardiographic study of 178 selected HCM patients, the group of patients (n = 73) with the obstructive form (resting peak gradient > or = 30 mmHg) presented more hypertrophy and poorer systolic and diastolic left ventricular (LV) functions than the HCM group (n = 105) without obstruction. LVOT peak gradient was positively correlated with hypertrophy (P < 0.0001) and negatively to tissue Doppler mitral annulus systolic (P = 0.0001) and early diastolic (P < 0.0001) velocities. The gradient significantly correlated with E/Ea ratio (r = 0.67; P < 0.0001). By multiple regression, LVOT gradient was related to E/Ea, LV maximal thickness and left atrial size. In comparison with patients without obstruction, patients with obstruction presented greater hypertrophy (P < 0.0001), lower systolic and early diastolic mitral annulus velocities (both P < 0.0001), higher E/Ea ratio (P < 0.0001) and higher global function index (P < 0.0001). In HCM, beyond the effects on hypertrophy, LVOT obstruction is an independent determinant of LV functional abnormalities.

Myocardial strain changes in Duchenne muscular dystrophy without overt cardiomyopathy

BACKGROUND

Patients with Duchenne muscular dystrophy (DMD) are at risk of the development of dilated cardiomyopathy and heart failure, thus making early identification of high-risk patients necessary. Myocardial strain imaging (MSI) can be used for quantitative analysis of wall motion of the left ventricle (LV). The aim of this study was to determine whether MSI could detect early changes in myocardial properties in presymptomatic DMD patients with normal LV function.

METHODS AND RESULTS

Two-dimensional echocardiographic and tissue Doppler examinations were performed in 13 DMD patients (age range, 11 to 20 years) with normal LV function and in 10 healthy controls. MSI was obtained from tissue Doppler information. In control subjects, strain values in both inner and outer layers of the myocardium were positive at the short-axis image showing the radial systolic thickening. In 10 of the 13 DMD patients, however, myocardial strain showed a negative strain value in systole in the outer layer of the posterolateral wall at the parasternal short-axis image for each cardiac cycle. In 5 of these 10 patients, the timing of the peak systolic velocity at the inferoposterior wall was delayed more than 60 ms than that at the posterolateral wall (mean 80.0+/-17.5 ms).

CONCLUSIONS

In some DMD patients with normal LV function, myocardial strain profiles at the posterolateral wall of the LV were different from those in healthy controls, suggesting abnormal myocardial contraction. MSI appears to detect early changes in myocardial features in DMD patients before the onset of overt cardiomyopathy.

Detection of left ventricular regional relaxation abnormalities in patients with hypertrophic cardiomyopathy by quantitative tissue velocity imaging

To assess the left ventricular regional relaxation abnormalities in patients with hypertrophic cardiomyopathy (HCM) by quantitative tissue velocity imaging (QTVI), Doppler echocardiography and QTVI were performed in HCM (n=10) and healthy subjects (n=11) at apical long-axis, two-chamber and four-chamber views. Regional early diastolic velocity (rVe) and regional atrial contraction (rVa) were measured at each segment of ventricular middle, basal and annular levels. Mean rVe and mean rVa at three levels as well as mean rVe/rVa ratio were calculated. Our results showed that transmitral inflow peak velocities during early diastole (E) and atrial contraction (A) were also measured and E/A ratio was calculated. The rVe of all left ventricular segments in HCM were lower than those in healthy subjects (P<0.05), but compared with healthy subjects majority of rVa in HCM were not different except inferior wall and anterior wall. E between HCM and healthy subjects was different (P=0.036), while mean rVe between them was significantly different (P<0.0001). Mean rVa and mean rVe/rVa of three levels were lower in HCM than in healthy subjects (P<0.05), but there were no differences in A and E/A between them (P=0.22, P=0.101). Left ventricular regional myocardial relaxation is reduced in HCM. Transmitral inflow E and A are influenced by preload, relaxation of myocardium and atrial contraction, etc., while rVe and rVa reflect myocardial relaxation function independently. QTVI is more sensitive and more accurate than conventional Doppler imaging for characterizingregional diastolic properties in HCM.

Tissue Doppler imaging for the evaluation of patients with hypertrophic cardiomyopathy

PURPOSE OF REVIEW

To discuss the role of tissue Doppler imaging for assessing regional myocardial function in patients with proven or suspected hypertrophic cardiomyopathy and review its application in clinical practice for diagnosis, estimation of filling pressures, and monitoring of treatment.

RECENT FINDINGS

Patients with hypertrophic cardiomyopathy have very abnormal systolic and diastolic myocardial function, even if global systolic function of the left ventricle appears normal. Regional function is most abnormal in walls that are markedly hypertrophied, but it is also abnormal in segments that are not affected by hypertrophy, and it is depressed in patients who have a mutation for hypertrophic cardiomyopathy but have not yet developed clear phenotypic changes. Genetic diagnosis remains difficult especially in sporadic cases, due to the very large number of mutations that have been identified; the hypertrophy may represent a nonspecific compensatory response to any mutation that impairs myofibrillar function. Subclinical changes especially affect long-axis ventricular function, and tissue Doppler imaging is the most sensitive test to identify reduced velocities of long-axis shortening and early diastolic lengthening of the left ventricle, prolonged contraction and relaxation times, and reduced strain in affected segments, both in patients with hypertrophy and in asymptomatic subjects with mutations. It can also discriminate well between hypertrophic cardiomyopathy and athlete's heart, and can be used with standard echocardiographic measurements to estimate left ventricular filling pressure or to monitor treatment.

SUMMARY

Tissue Doppler imaging can now be usefully incorporated into the routine echocardiographic study of patients with proven or suspected hypertrophic cardiomyopathy.

Differences in regional systolic and diastolic function by Doppler tissue imaging in patients with hypertrophic cardiomyopathy and hypertrophy caused by hypertension

OBJECTIVE

Doppler tissue (DT) velocity abnormalities have been described in patients with pathologic left ventricular hypertrophy (LVH). Impaired myocardial function has been suggested as a primary disorder in hypertrophic cardiomyopathy (HCM) and differences in DT parameters have been reported to be distinguishable from other LVH causes. We evaluated DT differences for patients with LVH caused by hypertension and patients with HCM, assessing regional systolic and diastolic function.

METHODS

A total of 62 participants were studied: 21 with HCM; 22 with LVH secondary to hypertension; and 19 control subjects. DT was used to record mitral annulobasal segment motion in the longitudinal axis. Systolic and diastolic velocities were measured at lateral and septal sites, and well-known ratios were obtained for diastolic assessment. A new global function index (GFI) that evaluates both systole and diastole was also calculated (GFI = [Emi/E(DT)]/S(DT) [s x cm(-1)], where mi is mitral inflow, E is E wave, and S is systolic wave).

RESULTS

Comparison showed significant differences in all parameters evaluated at the septal-basal segment and a GFI value of 1.77 showed 85% sensitivity and 75% specificity for detecting HCM when interventricular septum thickness was increased.

CONCLUSIONS

In the presence of unexplained LVH, markedly decreased DT velocities at basal septum efficiently detect myocardial dysfunction at this segment, and a calculated GFI > 1.77 strongly supports the diagnosis of HCM.

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.

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."