**1. Introduction**

Cardiomyopathy is a heterogeneous group of disorders of varying etiology. Heart failure from systolic and/or diastolic cardiac dysfunction is common to all. Certain disorders are distin‐ guished by life threatening arrhythmia. Onset of symptoms may be acute or progress from preclinical to symptomatic state over time and at a variable rate. Early recognition permits therapeutic intervention thereby retarding clinical progression and in some reversal or arrest of pathologic state. Echocardiography being the most frequently used and readily available cardiac imaging technique has established itself as the cardiac imaging modality of choice in diagnosis and longitudinal follow up of patients with cardiomyopathy. Complementary information from other imaging techniques, e.g., tissue characterization with cardiac MRI in iron overload states and evaluation of coronary anatomy with cardiac CT as in some cases of dilated cardiomyopathy, usually follows recognition of cardiomyopathy on echocardiogram.

An understanding of conventional echocardiogram and knowledge of novel applications of existing methods and emerging imaging echo techniques is important for effective clinical use of echocardiography.

#### **1.1. Standard 2-D and M-mode echocardiogram**

Standard echocardiogram includes analysis of myocardial and valvular structure, chamber quantification and estimation of function based on qualitative assessment and quantification by 2-D and M-mode echocardiography. Blood flow dynamics through different cardiac chambers and heart valves is assessed using spectral and color Doppler methods. Through prior work, pressure gradient across heart valves can be derived from measured flow velocity by using the modified Bernoulli equation (4V2 ); flow velocity is directly measured from

spectral Doppler display. Color Doppler techniques are useful in analyzing regurgitant valve lesions and in drawing attention to turbulent flow through stenotic valves as well as abnormal flow between cardiac chambers as in cases of atrial or ventricular septal defect.

**1.3. Doppler tissue velocity and doppler strain**

Modification of the spectral tissue Doppler technique with filters that display high amplitude and low velocity signal permits segmental interrogation of myocardium for both systolic and diastolic function. Tissue Doppler at the mitral annulus level has long been used to assess myocardial diastolic function. Reversal of high early diastolic velocity (E') with diastolic velocity coinciding with atrial systole (A') is a flow independent marker of diastolic impair‐ ment. An elevated ratio of early mitral inflow Doppler velocity (E) with early tissue Doppler velocity (E') is considered a reliable sign of elevated left ventricular end diastolic pressure [3-4].

Echocardiography Findings in Common Primary and Secondary Cardiomyopathies

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Color encoded display of myocardial velocities on a 2-D image of the LV permits parametric assessment of myocardial contraction and Doppler based interrogation of multiple myocardial segments in the same frame. The latter is used for estimation of myocardial velocity and strain (Figure-2). Myocardial velocity in the long axis determines myocardial displacement, which may be active contraction or passive motion from contraction of adjacent segments [5]. Hence, its usefulness is limited when assessing segmental function. On the other hand, Dopplerderived longitudinal and circumferential strain measures segmental myocardial lengthening or shortening (deformation), signifying active contraction of the interrogated segment [5]. Strain is a dimensionless index (change in length/original length) of myocardial mechanics. The technique has been used for determination of cardiomyopathy in hereditary conditions,

**Figure 2.** Color tissue Doppler derived tissue velocity (panel-A) and longitudinal strain (panel-B) is shown. Basal infero‐ septum and lateral walls are interrogated. Panel-A: time (x-axis) to peak systolic tissue velocity (y-axis) measured from the onset of QRS (ECG displayed at the bottom of each panel in green color) of inferoseptum (red) is delayed when compared to the lateral wall (yellow). This signifies dyssynchrony. Longitudinal strain is shown in panel-B. Inferosep‐ tum timing is again delayed. Note, however, that peak strain (strain is a negative value when measured in the long axis of the heart due to compression/shortening of the interrogated segment in systole) of inferoseptum is decreased

signifying contractile dysfunction.

#### **1.2. Three Dimensional Echocardiography (3DE)**

In patients with adequate imaging window, 3DE provides more accurate chamber quantifi‐ cation (Figure-1). Left ventricular end-diastolic and end-systolic volumes derived from 3DE has been validated against cardiac MRI [1], which is the current reference standard for such measurements. In routine clinical practice important use of 3DE derived chamber quantifica‐ tion is in establishing an accurate baseline, and in longitudinal follow up of patients. In addition to chamber quantification and determination of global left ventricular function, automated quantification also permits contractile assessment at regional and segmental level. The graphical display of this contractile information is plotted as segmental change in volume over time. Discrepant timing of this segmental volume change over time has been used to assess left ventricular dyssynchrony as that seen in patients with left bundle branch block (LBBB) pattern on ECG (Figure-1). However, concerns with reproducibility in patients with low left ventricular ejection fraction have compromised the diagnostic utility of this parameter in selecting patients for cardiac resynchronization therapy [2].

**Figure 1.** Panel-A: 3D data set of the heart is automatically cropped to display a 4-chamber and 2-chamber (not shown) projection of the heart. Left ventricular volume is tracked in end-diastole and end-systole from which volumet‐ ric LVEF is calculated. In panel-C segmental model of the heart is displayed. Each segment is color coded. Graphical display of the volume (y-axis) change over time (x-axis) is shown in panels-B and D. Each colored line corresponds to a segment of similar color in panel-C. In a normal heart all segments reach a minimum volume at the same time (panel-B). In panel-D there is a disarray of this time-volume curve signifying left ventricular dyssynchrony.

#### **1.3. Doppler tissue velocity and doppler strain**

spectral Doppler display. Color Doppler techniques are useful in analyzing regurgitant valve lesions and in drawing attention to turbulent flow through stenotic valves as well as abnormal

In patients with adequate imaging window, 3DE provides more accurate chamber quantifi‐ cation (Figure-1). Left ventricular end-diastolic and end-systolic volumes derived from 3DE has been validated against cardiac MRI [1], which is the current reference standard for such measurements. In routine clinical practice important use of 3DE derived chamber quantifica‐ tion is in establishing an accurate baseline, and in longitudinal follow up of patients. In addition to chamber quantification and determination of global left ventricular function, automated quantification also permits contractile assessment at regional and segmental level. The graphical display of this contractile information is plotted as segmental change in volume over time. Discrepant timing of this segmental volume change over time has been used to assess left ventricular dyssynchrony as that seen in patients with left bundle branch block (LBBB) pattern on ECG (Figure-1). However, concerns with reproducibility in patients with low left ventricular ejection fraction have compromised the diagnostic utility of this parameter in

**Figure 1.** Panel-A: 3D data set of the heart is automatically cropped to display a 4-chamber and 2-chamber (not shown) projection of the heart. Left ventricular volume is tracked in end-diastole and end-systole from which volumet‐ ric LVEF is calculated. In panel-C segmental model of the heart is displayed. Each segment is color coded. Graphical display of the volume (y-axis) change over time (x-axis) is shown in panels-B and D. Each colored line corresponds to a segment of similar color in panel-C. In a normal heart all segments reach a minimum volume at the same time (panel-

B). In panel-D there is a disarray of this time-volume curve signifying left ventricular dyssynchrony.

flow between cardiac chambers as in cases of atrial or ventricular septal defect.

**1.2. Three Dimensional Echocardiography (3DE)**

4 Cardiomyopathies

selecting patients for cardiac resynchronization therapy [2].

Modification of the spectral tissue Doppler technique with filters that display high amplitude and low velocity signal permits segmental interrogation of myocardium for both systolic and diastolic function. Tissue Doppler at the mitral annulus level has long been used to assess myocardial diastolic function. Reversal of high early diastolic velocity (E') with diastolic velocity coinciding with atrial systole (A') is a flow independent marker of diastolic impair‐ ment. An elevated ratio of early mitral inflow Doppler velocity (E) with early tissue Doppler velocity (E') is considered a reliable sign of elevated left ventricular end diastolic pressure [3-4].

Color encoded display of myocardial velocities on a 2-D image of the LV permits parametric assessment of myocardial contraction and Doppler based interrogation of multiple myocardial segments in the same frame. The latter is used for estimation of myocardial velocity and strain (Figure-2). Myocardial velocity in the long axis determines myocardial displacement, which may be active contraction or passive motion from contraction of adjacent segments [5]. Hence, its usefulness is limited when assessing segmental function. On the other hand, Dopplerderived longitudinal and circumferential strain measures segmental myocardial lengthening or shortening (deformation), signifying active contraction of the interrogated segment [5]. Strain is a dimensionless index (change in length/original length) of myocardial mechanics. The technique has been used for determination of cardiomyopathy in hereditary conditions,

**Figure 2.** Color tissue Doppler derived tissue velocity (panel-A) and longitudinal strain (panel-B) is shown. Basal infero‐ septum and lateral walls are interrogated. Panel-A: time (x-axis) to peak systolic tissue velocity (y-axis) measured from the onset of QRS (ECG displayed at the bottom of each panel in green color) of inferoseptum (red) is delayed when compared to the lateral wall (yellow). This signifies dyssynchrony. Longitudinal strain is shown in panel-B. Inferosep‐ tum timing is again delayed. Note, however, that peak strain (strain is a negative value when measured in the long axis of the heart due to compression/shortening of the interrogated segment in systole) of inferoseptum is decreased signifying contractile dysfunction.

in differentiation of physiologic hypertrophy in elite athletes from pathologic variants [6, 23], in assessment of myocardial dyssynchrony [7], and in differentiating constrictive from restrictive physiology.

Ratio of basal clockwise rotation to apical counterclockwise when viewed from the apex is as a measure of left ventricle twist or torsion. It is produced by contraction of helically ori‐ ented myofibers. Left ventricle torsion is affected in both systolic and diastolic myocardial dysfunction. When compared to a normal population, left ventricle torsion is decreased in dilated cardiomyopathy and increased in patients with hypertrophic cardiomyopathy [10].

Echocardiography Findings in Common Primary and Secondary Cardiomyopathies

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For this review a modification of 1995 World Health Organization /International Society and Federation of Cardiology (WHO/ISFC) Task Force on the Definition and Classification of Cardiomyopathies [11] and 2006 American Heart Association classification of cardiomyo‐ pathic disorders [12] is used. Discussion on echocardiographic findings will be limited to more

**•** Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D)

**•** Restrictive cardiomyopathy (non hypertrophied and non dilated) (RCM)

**•** Metabolic cardiomyopathy including amyloidosis and hemochromatosis

frequently encountered disorders and to conditions with unique echo features.

**2.1. Modified classification of primary and secondary cardiomyopathies**

**•** Hypertrophic cardiomyopathy (HCM)

**•** Left ventricular non compaction (LVNC)

**iii.** Acquired Primary and Secondary Cardiomyopathy:

**•** Tachycardia induced cardiomyopathy

**•** Stress provoked (takotsubo cardiomyopathy)

**•** Toxic cardiomyopathy: Alcohol and anthracyclines

**•** Connective Tissue Disorders: RA, SLE, PAN, scleroderma

**ii.** Mixed (pre-dominantly non genetic):

**•** Inflammatory myocarditis

**•** Peripartum cardiomyopathy

**•** Ischemic cardiomyopathy **•** Valvular cardiomyopathy

**•** Hypertensive cardiomyopathy

**•** Dilated cardiomyopathy (DCM)

**2. Echo findings in cardiomyopathies**

**i.** Genetic:

#### **1.4. 2D or speckle strain and LV torsion**

Doppler-based strain imaging is limited by angle dependency [8]. Innovation in imaging hardware and software now permit tissue-based measurement of segmental, regional and global myocardial function by determining tissue strain and torsion (Figure-3). The technique relies on good 2-D image quality for tracking tissue characteristics, termed "speckles", in regions of interest on a 2-D image through the entire cardiac cycle. To improve spatial resolution, image acquisition is performed at a slower frame rate contrasting with higher frame rate of Doppler-based techniques [9]. This may influence the accuracy of time dependent measurement of myocardial function as in milder forms of left ventricular dyssynchrony. Potentially valuable clinical information can be derived from speckle strain in a variety of cardiac disorders, including asymptomatic stages of cardiomyopathy [9].

**Figure 3.** Speckle strain measurement inlongitudinal and radial direction is performed.In Panel-A, longitudinal strain is determinedat multiple levels from base to apex. Because contraction in longitudinal direction results in fiber shorten‐ ing, strain values are negative. Segmental impairment of longitudinalstrain or contractility is present. In panel-B radial strain is depicted as a positive value due to fiber lengthening radially in systole. All segments at this level show normal contractility.LV torsion can be determined from the same data set.

Ratio of basal clockwise rotation to apical counterclockwise when viewed from the apex is as a measure of left ventricle twist or torsion. It is produced by contraction of helically ori‐ ented myofibers. Left ventricle torsion is affected in both systolic and diastolic myocardial dysfunction. When compared to a normal population, left ventricle torsion is decreased in dilated cardiomyopathy and increased in patients with hypertrophic cardiomyopathy [10].
