Distinguishing Systolic versus Diastolic Heart FailureA Practical Approach by Echocardiography

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1 Distinguishing Systolic versus Diastolic Heart FailureA Practical Approach by Echocardiography

Tasneem Z. Naqvi

Definition

Systolic heart failure is characterized by (1) signs and symptoms of dyspnea, easy fatigue and exercise intolerance, (2) a dilated left ventricle with or without a dilated right ventricle, (3) moderate to severe left ventricular systolic dysfunction associated with generalized left ventricular hypokinesis with or without segmental akinesis/dyskinesis, and (4) diastolic dysfunction that is often proportional to systolic dysfunction but may range from mild to severe. The right ventricle may be dilated and right ventricular systolic function may be normal to severely abnormal. Atrial enlargement is often proportional to ventricular enlargement, and atrioventricular valve regurgitation may range from mild to severe.

Diastolic heart failure is characterized by (1) signs or symptoms of shortness of breath, (2) normal or mildly abnormal systolic LV function, and (3) evidence of diastolic LV dysfunction out of proportion to systolic dysfunction. Normal or mildly abnormal systolic LV function implies both an LV ejection fraction (LVEF) greater than 50% and an LV end-diastolic volume index (LVEDVI) less than 97 mL/m2. Echocardiographic techniques required for the diagnosis and management of systolic and diastolic heart failure are described below.

Left Ventricular Dimensions and Thickness

See Appendix for reference values.

Key Points

• These values are measured in the parasternal long-axis (PLAX) (Figure 1-1) or parasternal short-axis (PSAX) view using 2D or M-mode.
• M-mode measurements should be made from leading edge to leading edge.
• Two-dimensional (2D) echocardiographic measurements should be made from trailing edge to leading edge.
• M-mode echocardiographic measurements are always slightly greater than 2D measurements because of these conventions.
• Measurement is made at the level of the LV minor axis, approximately at the mitral valve leaflet tips.
• LV mass is measured by M-mode at PLAX view or by 2D method at the midpapillary muscle level in the short-axis (SAX) view.
• These linear measurements can be made directly from 2D images or using 2D-targeted M-mode echocardiography (Figure 1-2; see also Figure 1-1).
• Ensure visualization of aortic and mitral valves.
• Maximize horizontal orientation of the interventricular septum.
• The M-mode cursor should be positioned perpendicular to the septum and LV posterior wall.
image

Figure 1-1 Measurement of left ventricular dimensions in the PLAX view in end-diastole (A) and end-systole (B) by 2D method. C, Measurement of LV dimensions by M-mode obtained from PLAX (A and B) or SAX (D) view. Orange arrow points at the RV chord that should not be included in the measurement of IVS thickness.

image

Figure 1-2 Dilated left ventricular dimensions in the PLAX view in end-diastole (A) and end-systole (B) in a patient with dilated NICM. Note enlargement of left atrium (>4.0 cm) and right ventricle (>3.3 cm).

Limitations

• LV posterior chords, anterior aberrant chords, and the tricuspid apparatus may be misinterpreted as the LV posterior wall and inner and outer borders of the anterior interventricular septum (IVS), respectively (see Figure 1-1C, orange arrow).
• End-diastole can be defined at the onset of the QRS complex, but is preferably defined as the frame after mitral valve closure or the frame in the cardiac cycle in which the cardiac dimension is largest.
• The M-mode cursor may be difficult to align perpendicular to the LV walls.
• Left ventricular mass can be measured by the M-mode or 2D method (Figure 1-3).
image

Figure 1-3 LV mass measurement is shown by 2D method. LV epicardium and LV endocardium are traced at end-diastole in mid–SAX view (A). LV end-diastolic length is measured from apical 4-chamber view (B).

Left Ventricular Systolic Function

Fractional Area Change

Key Points

• Fractional area change is obtained from the PLAX view by the M-mode or 2D method as (LVEDD − LVESD)/LVEDD × 100, where LVEDD is end-diastolic dimension and LVESD is end-systolic dimension (see Figure 1-1).
• It is easy to perform; however, it has technical limitations in the presence of segmental wall motion abnormalities and an abnormally shaped ventricle. 2D- and M-mode–derived ejection fraction by the Teichholz method are based on minor dimensions: (end-diastolic volume − end-systolic volume)/end-systolic volume where the end-diastolic volume = 7/(2.4 + EDD) × EDD3 and the end-systolic volume = 7/(2.4 + ESD) × ESD3. Because of geometric assumptions, these methods have been superseded by 2D volumetric methods.

Left Ventricular Volumes and Ejection Fraction (Table 1-1)

TABLE 1-1 ECHOCARDIOGRAPHIC ASSESSMENT OF LEFT VENTRICULAR SYSTOLIC FUNCTION

Method View Pitfalls
Two-Dimensional Imaging
Fractional shortening PLAX or PSAX Geometric Assumptions
Based on a single cross section
Ignores wall motion in nonmeasured segments
Ejection fraction (LVEDV − LVESV) × 100/LVEDV Dependent on load and heart rate (HR)
Modified Simpson’s rule 4-chamber and 2-chamber Foreshortening of apical views
Poor visualization of anterior wall
Area-length method 4-chamber (LV area)2 × 0.85/LV end-diastolic length Not appropriate for non-symmetrical LV
Assumes cylindrical LV shape
Bullet method Mid-SAX and apical 4- chamber LV shape assumption
Wall motion score index PLAX, PSAX, apical 4-, 2-, and 3-chamber
Average endocardial thickening score of 16 or 17 segments		 Reader and center variability
Requires visualization of all segments
Exercise ejection fraction As above To detect incipient LV systolic dysfunction
Usually eyeballed
Three-dimensional volumes Full-volume apical view Resolution is dependent on 2D image quality
Doppler Methods
LV stroke volume PLAX 2D and apical 5- or 3-chamber Circular shape assumption of LV outflow tract (LVOT)
Error in LVOT measurement
Errors are squared
LV dP/dt (mm Hg/s) MR CW Doppler Σ Δt 1 m/s to 3 m/s, 32/Δt Load independent
Not always feasible
MPI Apical 5-chamber Somewhat load dependent
No geometric assumption
Tissue Doppler Apical views
Objective data
Less dependent on image quality
Less dependent on reader expertise		 Somewhat load dependent
Requires parallel angle of insonation
Affected by translation, tethering, and respiration
2D speckle tracking Longitudinal Strain
Not affected by Doppler angle		 Requires high frame rate
Requires good 2D image resolution
Decreased feasibility versus TDI
Radial Strain
Not affected by Doppler angle		  

Key Points

• The most commonly used 2D measurement for volume estimations is the biplane method of disks (modified Simpson’s rule; Figures 1-4 and 1-5). Left-sided contrast agents used for endocardial border delineation are helpful and improve measurement reproducibility for suboptimal studies and correlation with other imaging techniques (Figure 1-6). These agents also help improve diagnosis of left ventricular thrombus (Figure 1-7).
• Left ventricular volumes are increased in systolic heart failure.
image

Figure 1-4 Reduced endocardial excursion and dilatation of four chambers in the same patient with dilated NICM in the apical 4-chamber view in end-diastole (A) and end-systole (B). Note enlargement of right ventricle and atrium.

image

Figure 1-5 Reduced endocardial excursion and dilatation of left ventricle and left atrium in the same patient with dilated NICM in the apical 2-chamber view in end-diastole (A) and end-systole (B). Use inspiratory or expiratory breath hold if necessary to define endocardial borders.

image

Figure 1-6 Apical 4-chamber views in end-diastole (A) and end-systole (B) before (C) and after (D) Definity contrast injection. Note clear delineation of endocardial borders in C and D compared to A and B.

image

Figure 1-7 Apical 4-chamber views in end-diastole (A) and end-systole (B) before and after (C and D) Definity contrast injection. Note clear delineation of LV apical thrombus (arrows) in C and D after contrast injection.

Limitations

• Difficult to quantify due to endocardial dropout.
• Foreshortening underestimates true LV volumes.
• Ejection fraction is often eyeballed without volume measurement.

Three-Dimensional (3D) Volumes and Ejection Fraction

Key Points

• More accurate than 2D assessment of LV volumes and ejection fraction.
• Overcome the limitation of foreshortening.

Limitations

• Image quality is dependent on 2D images.
• Requires postprocessing.

Segmental Wall Motion

Key Points

• Segmental wall motion abnormalities are often present in systolic heart failure.
• Dilated ischemic cardiomyopathy (ICM): hypokinetic segments as well as akinetic segments with or without thinning and increased echogenicity suggesting scar formation (Figure 1-8; see also Figures 1-6 and 1-7).
• Dilated non-ischemic cardiomyopathy (NICM): usually global hypokinesis; some segments may be akinetic, dyskinetic, or aneurysmal (see Figures 1-2, 1-4, and 1-5).
• LV thrombus may be present in the apical/distal IVS region or rarely at inferior/lateral aneurysmal segments (see Figure 1-7).
• Reversed IVS motion secondary to prior coronary artery bypass surgery is often present.
• Reversed IVS motion with or without apical and inferoapical dyskinesis occurs in the presence of left bundle branch block or RV pacing.
• Segmental wall motion is often normal in diastolic heart failure.
image

Figure 1-8 2D measurements for volume calculations using biplane method of disks (modified Simpson’s rule) in apical 4-chamber (A and B) and apical 2-chamber views (C and D) at end-diastole (A and C) and at end-systole (B and D) in a patient with dilated ICM. Papillary muscles should be excluded from the cavity in the tracing. Note thin and echodense basal to midinferior walls (red arrows in C and D) indicating prior inferior wall transmural infarct. Upper-normal LV diastolic (152 mL) and increased LV systolic (99 mL) volumes are present, which are characteristic of dilated ICM.

Limitations

• Requires good image resolution in all parasternal and all apical views.
• Requires technical expertise for interpretation.

LV Function Assessment by Tissue Doppler Imaging (Figure 1-9)

image

Figure 1-9 TDI velocities at septal annulus (A) and lateral annulus (B) and at the pulmonary veins (C) in a normal male adult age 30 years. A′, late diastolic velocity; D, diastolic pulmonary vein flow velocity; E′, early diastolic velocity; S, systolic pulmonary vein flow velocity; S′, systolic velocity.

Key Points

• Tissue Doppler imaging (TDI) provides more objective data and is less dependent on reader expertise.
• TDI systolic and diastolic velocities can be obtained reliably in basal and mid-myocardial segments by color-coded and pulsed wave (PW) Doppler techniques. Velocity of motion, displacement, and deformation can be measured in the longitudinal, radial, and circumferential planes.
• Global normal strain by TDI echocardiography ranges from 16% to 19%.

Limitations

• TDI systolic and diastolic velocities are age dependent.
• TDI velocities are decreased by increasing wall thickness.
• Requires parallel angle of insonation to area of interest.
• Affected by translational and respiratory motion.
• Significant variability.
• No standardized guidelines.
• Sample volume placement determines measurement precision.

LV Function Assessment by 2D Speckle Tracking (Figure 1-10)

image

Figure 1-10 Apical 4-chamber (A), 2-chamber (B), and 3-chamber (C) 2D strain maps and segmental strain scores along with bull’s-eye map (D) showing global strain (GS) and segmental strain values in the same patient as in Figure 1-8. Note reduced segmental strain values of −6 to −13% in the basal to midinferior and inferolateral segments consistent with transmural infarction. GS is mildly reduced at −16%. AVC, aortic valve closure.

Key Points

• Normal values for global longitudinal strain: 18.5% to 18.7%.
• Normal values for global radial strain: 47% ± 7%.
• Independent of cardiac translation and angle of insonation.
• Can measure radial, circumferential, and longitudinal strain as well as torsion.
• Less variable than ejection fraction.
• Feasible in approximately 80% of cases.
• Twist is normal in diastolic heart failure (DHF) and markedly reduced in systolic heart failure (SHF) (SHF: 5 ± 2.8, DHF: 13 ± 6.8, control: 14 ± 5.8).
• Circumferential strain is normal in DHF (15% ± 5%) and markedly reduced in SHF (7% ± 3%) (control groups: 20% ± 3%).
• Longitudinal strain is reduced in SHF (−4%) and DHF (−12%).
• Radial strain is reduced in SHF (14% ± 8%) and DHF (28% ± 7%).
• In patients with preserved ejection fraction (50%), regional longitudinal strain of ≤13% compared to other segments identified transmural myocardial infarction (MI) with 80% sensitivity and specificity (see Figure 1-10).

Limitations

• Requires harmonic imaging and high frame rate.
• Subject to image factors, including reverberation artifacts and attenuation.
• Requires technical proficiency in image processing.

Other Methods of Assessment of Left Ventricular Systolic Function

Key Points

• LV systolic function can be measured from rate of change of pressure gradients between the left ventricle and left atrium using the initial slope of the mitral regurgitation envelope as LV dP/dt.
• A normal dP/dt is greater than 1200 mm Hg/s (Figure 1-11).
image

Figure 1-11 Measurement of left ventricular dP/dt from MR envelope. Time for LV-LA gradient to increase from 4 mm Hg to 36 mm Hg is measured by calculating the time interval between MR velocity of 1 m/s to MR velocity of 3 m/s (corresponding to LV-LA gradients of 4 mm Hg and 36 mm Hg, respectively). This time is then divided by 32 mm Hg (36 − 4 mm Hg) to calculate dP/dt in mm Hg/s.

Limitations

• Not always feasible.
• Usual limitations of Doppler intercept angle.

Methods Evaluating Combined Systolic and Diastolic Function

Myocardial Performance Index

Key Points

• The myocardial performance index is defined as the sum of isovolumic contraction time (IVCT) and isovolumic relaxation time (IVRT) divided by ejection time (ET).
• It is useful in patients with primary myocardial systolic dysfunction.
• The myocardial performance index has prognostic value in various clinical settings because it seems to be independent of heart rate (Figure 1-12).
image

Figure 1-12 PW Doppler velocity curves of mitral inflow and left ventricular outflow. A is time from cessation to onset of mitral inflow (shown as 1); B is the left ventricular ET from onset to cessation of LV ejection (shown as 2). Myocardial performance index is (A − B)/B.

Limitations

• Somewhat load dependent.
• Combined mitral inflow and aortic PW Doppler is difficult to obtain for accurate time intervals.

LV Stroke Volume

Key Points

• Can be measured by PW Doppler of LV outflow tract and LV outflow diameter (Figure 1-13).
image

Figure 1-13 PW Doppler of the left ventricular outflow tract (A) and of the right ventricular outflow tract (B) in the same patient with NICM showing reduced peak ejection velocity and hence stroke volume for both left ventricle and right ventricle.

Limitations

• LV outflow diameter measurements may be imprecise, and error in measurement is squared.
• Assumes spherical shape of LV outflow.

Left Ventricular Diastolic Function

Mitral Inflow PW Doppler

Key Points

• PW sample volume is placed between the tips of the mitral valve leaflets or at the level of the mitral annulus.
• Ensure parallel alignment of the Doppler beam to blood flow.
• In dilated hearts, mitral inflow is often directed posterolaterally.
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