CHAMBER QUANTIFICATION Flashcards
What is not a cause of left atrial enlargement?
Left atrial enlargement reflects increased wall tension as a result of chronically increased left atrial pressure, which may be due to mitral regurgitation or stenosis. Also, impairment in left atrial function secondary to an atrial myopathy can lead to left atrial enlargement. Left atrial enlargement is also a marker of the severity and chronicity of diastolic dysfunction. Atrial septal defects commonly cause volume overload of the right heart resulting in right atrial enlargement rather than left atrial enlargement.
Which adverse event is not associated with left atrial enlargement?
Enlarged left atrial size is associated with adverse cardiovascular outcomes. These outcomes include an increase in (1) the incidence of atrial fibrillation and stroke, (2) the risk of overall mortality postmyocardial infarction, and (3) the risk of death and hospitalization in patients with dilated cardiomyopathy. In patients with diabetes mellitus, those with enlarged left atrial size are more likely to have major cardiac events or death. Enlarged left atrial size is not associated with pulmonary arterial hypertension. Interestingly, patients with pulmonary hypertension rarely have atrial fibrillation
Does left atrial function effect LV function?
The left atrium has three major physiologic roles that affect left ventricular filling and function. The left atrium acts as a (1) contractile pump that delivers 15%–30% of the entire LV filling, (2) reservoir that collects pulmonary venous return during ventricular systole, and (3) as a conduit for the passage of stored blood from the left atrium to the left ventricle during early ventricular diastole.
Caveats regarding measurement of LA size?
Transthoracic echocardiography is the recommended approach to assess left atrial size. Left atrial size cannot be accurately assessed with TEE because often the entire left atrium cannot fit in the image sector. With respect to the cardiac cycle, the left atrium is largest at the end of left ventricular systole. Accordingly, left atrial size and volumes should be measured at this time in the cardiac cycle rather than during left ventricular diastole. In order to obtain accurate measurements, dedicated left atrial images should be obtained that avoid foreshortening the left atrium. Measuring the left atrium from standard apical 2- and 4-chamber views acquired to measure left ventricular volumes is inadequate since the longitudinal axis of the left ventricle and left atrium frequently lie in different planes. The base of the left atrium should be at its largest size, indicating that the imaging plane passes through the maximal short-axis area. The left atrial length should also be maximized to ensure alignment along the true long axis of the left atrium. While the left atrial anteroposterior measurement obtained from the parasternal window is often reported because it is highly reproducible, it frequently underestimates left atrial size because this measurement assumes that when the left atrium enlarges, all its dimensions change in the same direction in a similar manner. This is often not the case during LA remodeling, which can be eccentric
How to accurately trace the LA border?
When tracing the borders of the left atrium, the confluences of the pulmonary veins, and LA appendage should be excluded. The atrioventricular interface should be represented by the mitral annulus plane and not by the tip of the mitral leaflets
Do LA volumes predict outcomes?
Left atrial volume is underestimated on two-dimensional echocardiography when compared to computed tomography and cardiac magnetic resonance imaging. This is due to differences in the manner in which the measurement is performed. With computed tomography and cardiac magnetic resonance, imaging slices are taken through the left atrium. The left atrium is traced on each slice and knowing the thickness of the slice, the volume of that slice is calculated. The slices are then all added up to obtain the total left atrial volume. With two-dimensional echocardiography, linear measurements of the left atrium from the 4- and 2-chamber views are obtained and then used in formulas to calculate left atrial volume. Left atrial volumes are powerful prognostic variables in disease states such as ischemic heart disease, atrial fibrillation, dilated cardiomyopathy and diastolic heart failure. Left atrial volumes are also more powerful prognosticators than left atrial anteroposterior diameter. This is because the left atrial anteroposterior diameter frequently underestimates left atrial size because it does not account for eccentric remodeling. Single-plane apical 4-chamber indexed LA volumes are typically 1–2 mL/m2 smaller than apical 2-chamber volumes.
Recommended method of measuring LA volume?
Disc summation method from single or biplane imaging assuming an oval shape.!
The methods using summation of discs are recommended instead. The LA endocardial border is traced and volume computed by adding the volume of a stack of cylinders of height h and area calculated by orthogonal minor and major transverse axes (D1 and D2) assuming an oval shape: LA volume = (π/4)h × Σ(D1)(D2). Alternatively, a biplane calculation could also be performed using the LA areas and lengths measured from both the apical 4- (A1) and 2-chamber (A2) views. LA volume is calculated as: LA volume = 8/(3π) × [(A1 × A2)/L] = 0.85 × [(A1 × A2)/L], where L is the shortest distance between the mid-line of the plane of mitral annulus to the opposite superior side (roof) of the left atrium measured in the 4- and 2-chamber views. While the area–length method still assumes an ellipsoidal LA shape, it has the advantage of reducing linear dimensions to a single measurement.
Left atrial volume can be calculated from three linear measurements using an ellipsoid model. However, this method is not recommended as the relative inaccuracy of these linear measurements limits this method.
What is the recommended method for reporting left atrial size?
Biplane disc summation method indexed for body-surface area.!
The American Society of Echocardiography guideline recommends that the body-surface area indexed left atrial volume be obtained from the biplane disc summation technique be reported. This is because it is theoretically more accurate than the area–length method because it incorporates fewer geometric assumptions. The upper limit of normality for two-dimensional echocardiography-derived left atrial volume is 34 mL/m2 for both genders. It is not recommended to report in routine clinical practice apical 4-/2-chamber linear measurements and nonindexed LA area and volume measurements. While left atrial size is dependent on gender, this difference is accounted for when adjusted for body-surface area.
Issue with using 3D method for measuring LA volume?
Lack of standardized methadology!
Three-dimensional echocardiography-derived left atrial volume measurements are limited by a lack of standardized methodology and limited normative data. However, it is superior to two-dimensional echocardiography-derived measurements as three-dimensional left atrial volumes are typically larger than two-dimensional volumes, which results in better correlation with cardiac computed tomography and cardiac magnetic resonance imaging-derived left atrial volume measurements. As well, compared to two-dimensional echocardiography, three-dimensional echocardiography-derived left atrial volume is more accurate when compared to a gold standard and it has a superior prognostic ability.
How to measure RA volume?
The American Society of Echocardiography guideline recommends using a dedicated apical 4-chamber view to measure right atrial volume, which should be calculated using single-plane area–length or disc summation techniques. The normal range for two-dimensional echocardiography-derived right atrial volume is 25 ± 7 mL/m2 in men and 20.5 ± 6 mL/m2 in women.
Features of the RA volume?
Similar to left atrial volume measurements, right atrial volumes are more robust and accurate compared to linear measurements. As well, right atrial volumes are underestimated on two-dimensional echocardiography compared to three-dimensional echocardiography. Unlike left atrial volume measurements, there are no standard orthogonal views to use for apical biplane calculation. Thus, right atrial volume is derived from the apical 4-chamber view using the area–length or disc summation methods. Right atrial volumes are also smaller than left atrial volumes. Finally, right atrial volumes are different between males and females and indexing for body-surface area does not account for this difference. The normal range for two-dimensional echocardiography-derived right atrial volumes is 25 ± 7 mL/m2 in men and 20.5 ± 6 mL/m2 in women
Effect of BSA, hypertension on aortic root?
Aortic root dilation is associated with aortic valve regurgitation. In fact, aortic regurgitation in the presence of chest pain and a dilated aortic root should raise concerns regarding possible aortic root dissection. Hypertension is associated with enlargement of the distal aortic segments but not the sinuses of Valsalva. Aortic root diameter measurements at the sinuses of Valsalva level are closely related to BSA and age. Therefore, BSA should be used to predict aortic root diameter. Aortic root dilatation at the sinuses of Valsalva is defined as an aortic root diameter above the upper limit of the 95% confidence interval of the distribution in a large reference population and can be detected by plotting observed aortic root diameter versus BSA on published nomograms
How to measure aortic root?
Two-dimensional echocardiography-derived aortic diameter measurements are preferable to M-mode measurements, as cardiac motion may result in changes in the position of the M-mode cursor relative to the maximum diameter of the sinuses of Valsalva. This translational motion may result in systematic underestimation (by approximately 2 mm) of the aortic diameter by M-mode in comparison with 2D measurements. While the American Society of Echocardiography/European Association of Cardiovascular Imaging recommends inner-edge to inner-edge aortic root measurements to be consistent with other imaging modalities such as cardiac magnetic imaging and computed tomography, previously established echocardiographic normative data was established using leading-edge to leading-edge measurements. The leading-edge method results in measurements that are larger on average by about 2 mm compared to the inner-edge measurement method. In tricuspid aortic valves, the closure line of the cusps is in the center of the aortic root lumen, and the closed leaflets are seen on the aortic side of a line connecting the hinge points of the two visualized leaflets. An asymmetric closure line, where the tips of the closed leaflets are closer to one of the hinge points, is an indication that the cross-section is not encompassing the largest root diameter. Transesophageal echocardiography-derived measurements are typically larger than transthoracic measurements.
How to measure the aortic annulus?
The aortic annular diameter is measured in the parasternal long-axis view, which is not the same plane containing the long axis of the left ventricle. Calcium is usually considered part of the lumen for the aortic annular diameter measurements and the presence of calcium can affect measurement accuracy. The aortic annular diameter measured in the parasternal long-axis view is typically between the noncoronary cusp and the right coronary cusp. The aortic annulus is not circular but elliptical and the diameter when measured from the parasternal long-axis view is close to the minor axis of the ellipse.
Measurement of the aortic annulus should be performed during mid-systole, when the aortic annulus is largest. All other aortic root dimensions (sinus of Valsalva, sinotubular junction ascending aorta) should be performed at end-diastole. No aortic measurements are recommended to be performed during isovolumetric relaxation or contraction.
Which of the following statements is false?
- An inferior vena cava measuring 1 cm with spontaneous collapse indicates the presence of intravascular volume depletion.
- Inferior vena cava diameters in mechanically ventilated patients are not reliable in the estimation of right atrial pressure.
- Inferior vena cava diameters in athletes are reliable estimates of right atrial pressure.
- The inferior vena cava is best assessed from the subcostal window.
Assessment of inferior vena cava size is best performed from the subcostal window and provides valuable information regarding right atrial pressure. However, dilation of the inferior vena cava in athletes is not an indication of elevated right atrial pressures. Studies have demonstrated that trained athletes can have a dilated inferior vena cava with normal collapsibility. Inferior vena cava diameters in mechanically ventilated patients are not reliable in the estimation of right atrial pressure as they may reflect the ventilator settings. An inferior vena cava that measures <1.2 cm with spontaneous collapse is often seen in the presence of intravascular volume depletion.
Which of the following is not a recommended view for assessing right ventricular function?
Apical 4-chamber view.
Right ventricle focused apical 4-chamber view.
Modified apical 4-chamber view.
Modified apical 3-chamber view.
The apical 4-chamber, right ventricle-focused apical 4-chamber and modified apical 4-chamber, left parasternal long and short axes, left parasternal RV inflow, and subcostal views are all recommended by the American Society of Echocardiography to adequately assess the right ventricle. The focused apical 4-chamber view is an optimal view for right ventricular measurements where the standard apical 4-chamber view is adjusted slightly to center the right heart on the screen and to ensure that there is no foreshortening. This is achieved by tilting the transducer in the apical 4-chamber view cranially and anteriorly. This is different from the right ventricle focused apical 4-chamber view where the transducer is tilted laterally and anteriorly (Fig. 4-8). The modified apical 3-chamber view is not a recommended view as it is a view that does not exist in the literature.
Abnormal RV function values?
RV size and function in this patient?
This patient has an abnormal right ventricular size and systolic function. From the two-dimensional apical 4-chamber view of the right ventricle , the dimension of the right ventricle at the base measures 42 mm. This is larger than the normal cutoff of 41 mm at this level, indicating dilation. Alternatively, a dimension >35 mm at the mid-level in the right ventricular focused view would also indicate right ventricular dilation. With respect to right ventricular function, from the tissue Doppler images of the lateral tricuspid annulus , the tissue Doppler-derived tricuspid lateral annular systolic velocity or S’ velocity is less than the normal cutoff of 9.5 cm/s indicating systolic dysfunction. As well, the M-mode image through the lateral tricuspid annulus or TAPSE is also <17 mm, which is consistent with the S’ velocity indicating right ventricular systolic dysfunction.
RV size and function in this patient?
This patient has a normal right ventricular size and systolic function. From the two-dimensional apical 4-chamber view of the right ventricle , the dimension of the right ventricle at the base measures 39.7 mm. This is smaller than the normal cutoff of 41 mm at this level, indicating normal size. Alternatively, a dimension <35 mm at the mid-level in the right ventricular focused view would also indicate normal right ventricular size. With respect to right ventricular function, from the tissue Doppler image of the lateral tricuspid annulus , the tissue Doppler-derived tricuspid lateral annular systolic velocity or S’ velocity is greater than the normal cutoff of 9.5 cm/s indicating normal systolic function. As well, the M-mode image through the lateral tricuspid annulus or TAPSE is also >17 mm, which is consistent with the S’ velocity indicating normal right ventricular systolic function.
Features of RV systolic function?
Right ventricular fractional area change <35% indicates systolic dysfunction. This measurement must be performed on an image that includes the entire right ventricle during systole and diastole in the apical 4-chamber view. As well, it should be measured including the trabeculae in the right ventricular cavity. Right ventricular index of myocardial performance (RIMP) is calculated using the formula: RIMP = (isovolumic contraction time + isovolumic relaxation time)/right ventricular ejection time or RIMP = (tricuspid valve closure-to-opening time−right ventricular ejection time)/right ventricular ejection time. The isovolumic contraction time, the isovolumic relaxation time and ejection time intervals should be measured from the same heart beat using either pulse-wave spectral Doppler or tissue Doppler imaging velocity of the lateral tricuspid annulus (Fig. 4-9). It must be noted that RIMP can be falsely low in conditions associated with elevated right atrial pressures, which will shorten the IVRT. A RIMP >0.43 by PW Doppler and >0.54 by TDI indicate RV dysfunction. Tricuspid annular plane systolic excursion (TAPSE) is measured by M-mode with the cursor aligned in the direction of the tricuspid lateral annulus. Although this index predominantly reflects RV longitudinal function, it has good correlation with parameters estimating RV global systolic function, such radionuclide right ventricular ejection fraction and two-dimensional echocardiography right ventricular fractional area change and ejection fraction. Care should be taken in relying on TAPSE, as the measurements may over or underestimate RV function due to overall heart motion. While there may be minor variations in TAPSE values according to gender and body-surface area, overall a TAPSE <17 mm is suggestive of right ventricular systolic dysfunction. TDI-derived tricuspid lateral annular systolic velocity (S’) wave should be measured on an image where the basal segment and the annulus aligned with the Doppler cursor to avoid velocity underestimation. An S’ velocity <9.5 cm/s indicates RV systolic dysfunction.
What is the LV segmentation model?
The 17-segment model is recommended to standardize left ventricular segmentation across cardiac imaging modalities . This model is essentially the 16-segment model with the addition of an apical cap, which is defined as myocardium beyond the LV cavity. In the 16-segment model, the left ventricle divides the basal and mid-ventricular levels into six segments each and the apical level into four segments. Starting at the anterior junction of the inter-ventricular septum and the right ventricular free wall and continuing counterclockwise, basal and mid-ventricular segments should be labeled as anteroseptal, inferoseptal, inferior, inferolateral, anterolateral, and anterior. The apex includes septal, inferior, lateral, and anterior segments. There is no 15-segment model.
