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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5769_Библиотеки_им_академика_М_И_Перельмана
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320 oracic ultrasound
Table 5 – Normal values of cardiac measurements in M-Mode
Measurement Range (cm) Average (cm)
Age(years)
Bodysurfacearea(m2)
Sizeoftherightventricle(supine)
Sizeoftherightventricle(lat.left)
Sizeoftheleftventricle(supine)
Sizeoftheleftventricle(lat.left)
Post.wallthickness.leftventricleAverage
septalthickness
Apicalseptalthickness
Sizeoftheleftatrium
Aorticrootsize
Separationaorticcusps
Percentagefractionalshortening
13-54
1.45-2.22
0.7-2.3
0.9-2.6
3.7-5.6
3.5-5.7
0.6-1.1
0.3-0.8
0.5-1.2
1.9-4
2-3.7
1.5-2.6
34-44%
1.8
1.5
1.7
4.7
4.7
0.9
0.5
0.7
2.9
2.7
1.9
36%
➣ Left ventricle: is it small? is it big? does it move?
Accurate measurements of the heart chambers can be performed either by M-Mode or twodimensional scans. e immediate visual assessment in two dimensional imaging allows
anyway, once the physician is familiar with normal situations, to assess whether the size of
the heart chambers are within normal limits, increased or reduced7. In the apical 4 chambers
scan, the left ventricle appears larger (no more than 5.5 cm in its telediastolic transversal
diameter) than the right, which shows a diameter no more than two thirds of the left ventricle (maximum diameter at the base 4.2 cm), and this first quick estimate can immediately
provide very useful information (Fig. 24) (Clip 14). A patient with severe hypovolemia has,
in the absence of pre-existing heart disease, reduced volumes and widespread hyperkinesia.
Figure 24 – Immediate visual detection of cardiac pathology in B-mode. A: normal heart (four
chambers view). B: pathologic heart. Biatrial enlargement and abnormal ventricular geometry. A left
ventricle that loses its ogival shape (truncated rugby ball) and becomes irregularly spherical, does not
exhibit a normal systolic function.
Echocardiography 321
Clip 14 – Apical 4 chambers scan in normal subject. The left ventricle is
more large than the right one. The biventricular kinetics is normal.
A subject with globally impaired left ventricular function shows echographic signs which
can be simply and visually estimated in few B-Mode scans, if the clinician knows the normal
systolic behavior of the heart.
In parasternal long axis view, during the normal systole, the septum movement/thickening
is toward the long axis of the ventricle and symmetric with the movement of the left ventricular posterior wall. In 4 chambers view this movement/thickening is toward the lateral
left ventricular wall (Fig. 25).
Figure 25 – Above: End-diastolic and end-systolic apical four chambers images of a normal subject. In
this view, during the systole the septum moves toward the ventricular axis symmetrically with the lateral wall,
and the apex is close to the mitral plane (longitudinal shortening). Below: systolic activity of the left ventricle
in parasternal long axis view. In this scan mutual movements affect the septum and the posterior wall.
A more precise assessment of the systolic function is highly dependent on detection of the
endocardial borders and is employed for the estimation of the fractional shortening of the
left ventricle, fractional change of the left ventricular area and the ejection fraction8 (see below). In critically ill patients an accurate quantitative evaluation of the ejection fraction may
be difficult (Fig. 26, 27). e visual assessment (eyeballing) of the ejection fraction is easily
obtainable and sufficiently accurate, even when not determined by cardiologists6.
In parasternal short axis view (papillary muscle level), during systole the miocardium thickens
and the endocardic contour of the left ventricle moves symmetrically toward the center of
the ventricle. Dysfunctional myocardium exhibits decreased thickening or even thinning. An
asynchrony of the septal movement appears in left bundle branch block9.
A useful visual estimate of global left ventricular systolic function consists of measuring in
parasternal long axis view the distance between the septum and the anterior leaflet of the
mitral valve during its maximum diastolic excursion (corresponding to the rapid diastolic
filling) (Fig. 28). is value must not exceed 0.7 cm10.
322 oracic ultrasound
Figure 26 – Above: End-diastolic and
end-systolic apical four chambers images
of a normal subject. Below: Apical four
chambers view of the some subject. Left:
end diastolic volume. Right: end systolic
volume. The ejection fraction calculated
by Simpson method is 54%.
Figure 27 – Four and two chambers views
for assessing telediastolic and telesystolic
volumes, and ejection fraction by Simpson
method in a patient with acute heart failure
in ER. Note that the endocardial borders
are not fully detected and the two chamber
view is not truly apical.
Figure 28 – The motion of the diastolic anterior mitralic leaflet toward the septum is an index of global
left ventricular systolic function. Normally, the distance between the septum and the anterior leaflet of
the mitral valve during its maximum diastolic excursion must not exceed 7 mm. In this case the distance
is around 9 mm.
Echocardiography 323
Another help for detecting the left ventricular systolic dysfunction is obtained by observing in
4 chambers view the systolic shift of the lateral mitral ring toward the apex. is movement
is the expression of the normal longitudinal shortening of the heart during systole. A value
greater than 13 mm is normal, a value below 13 mm is indicative of systolic dysfunction
(Fig. 29). e use of M-Mode imaging greatly improves these measurements.
Figure 29 – The normal shift of the lateral mitral ring toward the apex during the systole. Bi-dimensional
and M-Mode representation.
e assessment of segmental kinetics provides considerable experience and it is not easy to
learn (Clip 15).
Clip 15 – Apical 5 chambers scan. Akinesia limited to the cardiac apex.
Normal kinetics of the remaining segments.
Analysis of regional ventricular function as a diagnostic aid is useful when diagnosing a disease
that causes a localized, regional abnormality rather than diffuse, global dysfunction. us,
wall motion analysis is most commonly applied in ischemic heart disease.
Myocardial ischemia can be diagnosed and localized with excellent accuracy from visual
inspection of wall motion. Indeed the relationship between infarction and dysfunction is so
close that the lack of a wall motion or wall thickening defect rules out clinically significant
infarction.
Commonly, regional function is assessed by dividing the left ventricle into 17 segments and
assigning a qualitative grade to each of them ranging from 1 to 5. e severity of dysfunction
is scored visually in each segment as 1 for normal contraction or hyperkinesis, 2 for hypokinesis, 3 for akinesis, 4 for dyskinesis, and 5 for aneurysmal segments (see Chapter 11). is
method is observer-dependent.
e observation of severe systolic dysfunction resulting from the involvement of numerous
segments, definitely requires a less complex learning curve. A severely compromised hemodynamics is justified by severe systolic dysfunction and is therefore more easily detectable
(Clip 16-21).
324 oracic ultrasound
Clip 16 – Apical 4 chambers scan. Patient arriving in the ER with respiratory
distress and hypotension. A sharp reduction of the systolic function of the left
ventricle is evident.
Clip 17 – Apical 4 chambers scan. Patient with severe dyspnea. Obvious
moderate dilatation of all cardiac chambers and severe reduction in the
pumping function of the left ventricle. Pacemaker lead in the right atrium.
Clip 18 – Parasternal long axis scan. Patient with dilated cardiomyopathy
in shock. Severe systolic dysfunction.
Clip 19 – Subcostal 4 chambers scan. The left cavities appear dilated and
the systolic function of the left ventricle is severely depressed.
Clip 20 – Apical 5 chambers scan. Patient with chest pain and ECG showing
a large anterior infarction. Akinesia of the septum and apex with severe
impairment of the pumping function.
Clip 21 – Apical 4-5 chambers scan. Patient with shock. Severe reduction of
the pumping function of the left ventricle.
It is estimated that about a third of acute left ventricular failure is secondary to diastolic
heart failure11. e echocardiographic assessment of diastolic function is more complex and
provides for Doppler evaluations.
When the systolic function is normal, lung ultrasound can add crucial information and suggests the etiology of cardiogenic dyspnea (Clips 22-23).
Clip 22 – Apical 5 chambers scan. Patient with a history of hypertension and
hypertensive heart disease. Severe dyspnea, PA 180/110. Echocardiography
detects discrete hypertrophy of the left ventricular walls and normal systolic
function. Chest ultrasound showed a diffuse interstitial syndrome, confirming
the cardiogenic nature of dyspnea.
Clip 23 – Lung ultrasound shows diffuse bilateral B Lines confirming the
cardiogenic nature of dyspnea.
Echocardiography 325
Assessment of the left ventricular systolic function
e next three paragraphs introduce more advanced information about ultrasound and
Doppler quantitative evaluation of the left heart. Chapter 11 will examine the role of ultrasound for further cardiac and hemodynamic estimates. ese notions go beyond Focused
Cardiac Ultrasound and are recommended for more experienced sonographers and for those
who are keen to acquire a better diagnostic skill.
e evaluation of the left ventricular systolic function is of fundamental importance in the
critically ill patient and it is based on the principles described above. ere is no doubt that the
“eyeball” assessment of the ejection fraction (EF), after a relatively short training, is comparable
to more complex measurements12. However, sometimes a visual or semiquantitative estimation of the ejection fraction does not exhaust the evaluation of the left ventricular function.
is parameter does not only depend on the myocardial contractility, but also on preload,
afterload and heart rate. erefore the cardiac contractility should be supplemented with
additional data that can be clinical, but also echographic (for example, the preload and
afterload estimates).
FE is defined as the stroke volume (SV) divided by the telediastolic volume (Vtd), i.e. V
- V
td
ts
/ Vtd, where Vts corresponds to the telesystolic volume. In addition to visual and qualitative
assessment, FE is a continuous numerical parameter. It can be estimated using different
quantitative methods and with different complexity. By way of example, and in view of
the ease with which these data can be captured, we briefly describe two two-dimensional
echographic approaches: the fractional reduction of the area in short-axis, and Simpson’s
volumetric method13.
e first method estimates the planimetric variation of the area of the left ventricle between
telediastole and telesystole, which normally varies between 38% and 60%. is approach
is via a parasternal short axis scan at the level of insertion of the papillary muscles. e area
in the two images (diastolic and systolic) is drawn manually and the machine automatically
calculates its value (Fig. 30).
is estimate is easily completed if the endocardial border is well detected, but it may be
inaccurate if there are defects in segmental contractility, as in ischemia or left bundle branch
block, or in the case of right ventricular dysfunction.
Moreover, the estimation of the planimetric variation of the left ventricular area has reduced accuracy if the imaging planes used for the measurement are incorrect (i.e. off-axis or
foreshortened).
Using the right technique on the right patient, this method correlates well with the FE assessed with radionuclide and the variability between observers is around 5%.
Simpson’s method as well correlates with the angiographic FE. In this case the endocardial
border is drawn manually using the slider on two orthogonal apical projections (4 and 2
chambers), and the machine automatically integrates the data and produces the result in
volumes (in ml) and FE (%) (Fig. 31). It is recommended that these measures are produced
as the average of estimates over a number of systoles (especially in the case of atrial fibrillation), captured in the expiratory phase.
With any method, the endocardium needs to be accurately detected to ensure accurate left
ventricular cavity assessment. With methods requiring manual measurement of the left
ventricular cavity, errors can arise from a wrong perception of the endocardial line between
different people. Also important for ejection fraction calculation is the perfect detection of
true end-diastole and end-systole.
326 oracic ultrasound
Figure 30 – Above: parasternal long axis view of the left ventricle. In this view, during the normal
systole, the septal movement/thickening is toward the long axis of the ventricle and symmetric with the
movement of the left ventricular posterior wall. This dynamics symmetrically decreases the telediastolic
area of the left ventricle, determining the fractional reduction of the left ventricular area in short-axis
(below).
Figure 31 – Above: Ejection fraction measured in a normal subject. Below: ejection fraction in a patient
with severe systolic dysfunction.
Echocardiography 327
Finally, for the Simpson method, the ventricle can be foreshortened on apical images, so that
the true apex will not be imaged.
Assessment of the left ventricular diastolic function
e complete assessment of a subject with heart failure, including the presence of a wet lung,
requires the evaluation of the diastolic phase of the cardiac cycle. About half of patients with
a new diagnosis of heart failure has a normal or nearly normal systolic function, but their
diastole is more or less impaired14. Such subjects may have a diastolic heart failure, also called
congestive heart failure with preserved FE.
e left ventricular diastole is the period ranging from the end of aortic outflow to the beginning of the ventricular muscular tension of the following systole. In this phase many active
and passive processes are involved. ey affect the transmitralic flows, the atrioventricular
pressure gradients, and finally the left ventricular end-diastolic pressure. In the diastolic phase,
the presence of a high compliance cardiac chamber, identifiable with the left ventricle that
fills up when the atrial pressures are low, is the requirement for a dry lung and for an eupneic
patient. Elevated left ventricular filling pressures are therefore a physiological consequence
of diastolic dysfunction.
As already mentioned, left atrial enlargement is a sign of diastolic dysfunction and of increased
left ventricular filling pressure, and shows a significant correlation with atrial remodeling,
Doppler indices of diastolic failure and cardiac morbidity and mortality.
Symptomatic patients with diastolic dysfunction usually have increased left atrial pressure and
systolic pulmonary pressure. Suggestive for diastolic dysfunction is the presence of dyspnea
and wet lungs in patients with preserved systolic function and myocardial hypertrophy.
More precisely, left heart failure with preserved systolic function is diagnosed and classified
with the use of pulsed Doppler, for its ability to accurately estimate the transmitralic flows15.
e basis of this method lies in the fact that, in the absence of mitral stenosis or constrictive
pericarditis, the speed profile of forward flow through the mitral valve is influenced by the
pressure gradient existing between the two cavities and by the compliance of the left ventricle.
With a sinus rhythm the velocity profile is biphasic, with an early diastolic wave (E) and a
late wave, caused by atrial contraction (A). Normally the wave E is taller than wave A (E/A
ratio 1.88 to 1.28), although after 60 years this ratio may slightly reversed (0.96). With advancing age, the E wave deceleration time (the time that goes from the apex of E wave to the
baseline - extrapolated, if not real-) also increases. is value is variable between 142 msec in
young people and 200 msec after 60 years (Fig. 32).
With good quality images, the acquisition of these data is relatively easy. An apical 4 chambers
scan is made and the sampling gate of pulsed Doppler (1-3 mm) is placed between the tips
of the mitral cusps, so as to register the diastolic flow profile approaching.
E/A ratio that falls below 1 and deceleration time that extends above 220 msec is diagnostic
of impaired relaxation (or grade 1 dyastolic dysfunction) (Fig. 31). is dysfunction is characterized by decreased left ventricular compliance with normal left atrial pressure (ventricular
hypertrophy, older people). If left atrial pressure rises because of the progression of the disease,
an increase in E wave amplitude and a decrease in the deceleration time appear. is modification restores a normal E/A ratio, therefore the flow trace shows a pseudonormal morphology.
is pathologic pattern, correctly defined pseudonormal or grade 2 diastolic dysfunction, is
characterized by a supernormal left atrial pressure.
328 oracic ultrasound
Figure 32 – Above: the normal transmitralic flow. E wave is taller than A wave. Below: Impaired
relaxation. E/A ratio is less than 1. E wave deceleration time is increased (0.253 sec). Apical four
chambers view.
With severe left ventricular diastolic dysfunction early high speed filling in a short time occurs,
producing a high and short E wave (high E/A ratio). A dysfunction of this type is classified
as grade 3 (or reversible restrictive syndrome) and grade 4 (irreversible restrictive syndrome).
It should be remembered, however, that this assessment is not capable of reliably distinguish
between normal and pseudonormal cases. Further study can be conducted with functional
tests (e.g. Valsalva maneuver), the analysis of the flow in the pulmonary veins or the propagation velocity of the flow in M-Mode. Because of its relative simplicity, we briefly describe the
use of tissue Doppler imaging (TDI).
TDI is used to measure the velocity of cardiac structures instead of flows. In this specific
case, it measures the speed of mitral annulus during early ventricular filling (E’ wave), which
is influenced by the distensibility of the left ventricle.
Operationally, an image of the heart-4 chambers is acquired and the appropriate sampling
gate of TDI is aligned (angle <20°) with the longitudinal motion of mitral annulus, in the
septal or lateral position (Fig. 33).
e machine tracks in this case a positive wave (correlated with the systole and with the FE)
and two negative waves similar to the waves E and A of the mitral inflow (defined E’ and A’).
Even in this case, the normal E’ wave is wider than A’ (Table 6).
Table 6 – Normal velocity values (cm/sec) for the mitral annular movements detected by Tissue
Doppler Imaging
E’ A’ E’/A’
Septal
Lateral
Anterior
Posterior
12±3
13±3
12±3
14±4
10±2
11±3
10±3
12±3
1.5±0.6
1±0.7
1.2±0.7
1.3±0.7
Echocardiography 329
In case of E/A ratio pseudonormality, a reversal of the E’/ A’ ratio or at least an E’ wave less
than 8 cm/sec indicate grade 3 diastolic dysfunction.
As we will see later, TDI associated with the sampling of the mitral inflow allows also to
estimate the left ventricular filling pressure.
Figure 33 – Above: normal transmitralic flow. E/A ratio > 1. Below: Tissue Doppler imaging of the
septal mitral annulus motion. The normal E’ wave is wider than A’ wave. E/E’ ratio is low (5.6).
In many critical situations, the echocardiographic pressures estimation and the evaluation
of the diastolic cardiac performance, implemented by more complex methods (transmitral
flows, tissue Doppler, transmitral velocity of propagation), may not be easy.
Table 7 and Fig. 34 summarize the Doppler parameters for the assessment of diastolic
dysfunction.
Table 7– Doppler parameters for the assessment of diastolic function
Doppler parameter Normal Impaired relaxation Psuedonormal Restrictive
MitralDoppler
E/A
Decelerationtime
TDI
E’ 10-15cm/sec <8cm/sec <8cm/sec <8cm/sec
>1
<220msec
<1
>220msec
1-2
150-200msec
>2
<150msec
Assessment of the left ventricular filling pressure (LVFP)
LVFP is the pressure existing in the cavity at the end of diastole. In the absence of obstacles
to the blood flow, it reflects the pulmonary capillary pressure or wedge pressure. In general
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