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Hvordan bedre cardiac vindu
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Cardiac UL - Focused questions
- Pericardial effusion
- Global function/contractility
- Signs of right ventricular strain
Which ventricle lies more anterior/closer to the probe
The right ventricle (The heart is slightly anteriorly rotated)
Which two views allow for four-chamber visualization and comparison of right and left ventricular cavity size?
The apical and subxiphoid views
Probe positioning for subxiphoid/subcostal
Plce the probe in the subxiphoid position Aim toward the left shoulder and place the probe at a 15-degree angle to the chest wall. The probe indicator should be pointing toward the patient’s right (Start with the screen at maximum depth)
Subxiphoid/subcostal - Orientation
Tip for problem with visualizing the subcostal view (4)
- Try increasing the depth to its maximal level to make sure the beam is reaching the part of the thoracic cavity containing the heart
- Flatten the probe on the abdominal wall to make sure the beam is angling toward the left thoracic cavity
- Slide the probe over to the right to use the liver as an acoustic window and to get away from the stomach, which may be scattering the sound waves
- Have the patient bend his or her knees if possible. This helps relax the abdominal wall muscles and can sometimes make visualization clearer
Parasternal long axis view - How
Assuming the long axis of the heart to be from the patient’s right shoulder to the left hip, the transducer probe should be placed in the third or fourth intercostal space, immediately left to the sternum
The probe indicator should be pointing toward the 5 o’clock/left hip position
Which three points define the plane of the parasternal long axis view
(When these three structures are visualized simultaneously, the probe is oriented correctly along the long axis of the heart.)
- Mitral valve
- Aortic valve
- Cardiac apex
Important function of parasternal long axis in relation to pericardial effusion
Can help distinguish pleural from pericardial effusions. Large pleural effusions can appear to surround the heart, but they will taper to the descending aorta, which can often be seen in the parasternal view. Pericardial effusions will cross anterior to the descending aorta.
(This is because the pleura will insert where the descending aorta travels through the thoracic cavity.)
How to find the parasternal short-axis view
Assume the short axis to be from the patient’s left shoulder to the right hip.
The transducer probe should be placed in the 3rd or 4th intercostal space, immediately left of the sternum.
If the parasternal long-axis view has already been obtained, simply rotate the transducer 90 degrees clockwise toward the patient’s right hip. Usually this view visualizes the mitral valve in cross-section. By sliding toward the right shoulder the aortic valve can be seen and toward the left hip the heart’s apex.
How to help find the parasternal long-axis view (4)
- Try angling the probe obliquely to sneak through the intercostal space
- Try sliding the probe along the 3rd or 4th intercostal space toward and away from the sternum. Occasionally, the long-axis view is not adajcent to the stenrum but more in the midline of the thoracic cavity
- Have the patient lie in the left lateral decubitus position to bring the heart closer to the chest wall and limit interference from the lung
- Have the patient have his arms over his head
Tip for visualizing the parasternal short-axis view (2)
- Try sliding the probe in the intercostal space toward and away from the stenrum.
- Try angling the probe obliquely
- Try having the patient have his hands over his head
- If the patient can sit forward or be positioned in the left lateral decubitus position, the heart will be brought forrward in the chest and will be closer to the probe, making for easier scanning
Parasternal short-axis - Name the three views
- Aortic valve
- Mitral valve
- Mid-ventricle (papillary muscle visible)
Parasternal short-axis - Which level
Mitral valve
By tilting the transducer downward but staying perpendicular to the long axis of the heart, you will first arrive at the plane of the mitral valve. Here the mitral valve is seen orthogonally with its anterior as well as posterior leaflet. This view is ideal to observe the opening and closing motion of the mitral valve; this motion has been compared to a fish opening and closing its mouth.
The PSAX base view should not be used to assess LVF. You are too far at the base of the ventricle here. These segments are not representative.
Parasternal short-axis - Which level
Aortic valve view
Parasternal short-axis - Which level
Mid-ventricle / Papillary-muscle level
By tilting the transducer even further towards the apex you will gradually see the papillary muscles appearing. Now you are transecting the left ventricle nearly in the middle. The papillary muscle may vary in terms of size as well as position. The right ventricle is also seen in this view, but is more narrow here than on the PSAX LV base view. This view is ideal to inspect features such as left ventricular function (regional and global), the size of the ventricles, and characteristics of left ventricular hypertrophy.
Orient the image, name the different structures
It is important to adjust the image so that the aortic root is seen as a round structure in which all three aortic valve cusps are visible. The appearance of the aortic valve during diastole resembles that of a “Mercedes star”.
Given good quality of the image, you will be able to visualize the origins of the coronary artery, especially that of the right coronary artery. The aorta is in the “center” of the image, surrounded by the left atrium, the interatrial septum, the right atrium, the right ventricle and the pulmonary artery (starting at the bottom and moving in clockwise direction). From here you can see all cusps of the aorta. Therefore this view is ideal to observe the opening and closing motion of the aortic valve. This view also enables you to estimate the size of the left atrium and detect interatrial septal defects (ASD). However, in most cases you will have to use an atypical short-axis view from a position that is one or two intercostal spaces lower in order to detect atrial septal defects. The PSAX base view should also be used to study the tricuspid valve and identify any membranous ventricular septal defect, pathologies of the right ventricular outflow tract (RVOT), or the pulmonary valve (PV). Use a modification of the PSAX base view to assess the PV and the pulmonary artery: direct the transducer more to the left and tilt it ventrally. Sometimes it may be necessary to obtain the image from a lower intercostal space. Here it is possible to see the bifurcation of the pulmonary artery and its branches. The right pulmonary artery is visualized here as it passes beneath the aortic arch. This view will also permit you to detect a patent ductus arteriosus (PDA).
How to find the apical four-chamber view
Usually located along the T4-5 level or nipple line. Position the transducer at the patient’s PMI or about the 5th ICS, aiming toward the patient’s right shoulder.
The probe indicator should be pointed toward the patient’s right.
If possible, rotate the patient onto his or her left side to reduce any lung artifact and to bring the heart closer to the anterior chest wall.
Tip for obtaining the apical four-chamber view
- Have the patient in left lateral decubitus position or sitting forward
- Have the patient have his hands above his head
- Sometimes sliding the probe around where you think the PMI might be will result in a recognizable image popping into view
- Try to start with a parasternal long-axis view, and slide the probe laterally along the chest wall until the apx is centered on the screen. Then adjust the angle and direction of the transducer to create an apical window
Name the chambers in the A4C view
How to measure the right and left ventricle diameter
Normal and abnormal values
Measure the width from the myocardial inner wall to septal inner wall at the level of the tricuspid and mitral valves.
Normally the ratio of right ventricle diameter to left ventricle diameter is < 0.5.
Some authors use > 0.7 and some > 1.0 to indicate a dilated right ventricle
(Abnormal movement of the septum away from the right ventricle / toward the left ventricle indicates increased right ventricular pressures. Normally the right ventricle is a low-pressure system, and therefore relaxation would mean the septum would bow away from the right ventricle.)
Forkortelser - LVIDd og LVIDs
Left ventricular internal diameter end diastole and end systole.
Normal LVIDd: 3.5-5.6 cm
Normal LVIDs: 2.0-4.0 cm
Forkortelser - IVSd og IVSs
Interventricular septal end diastole and end systole. The normal range is 0.6-1.1 cm.
The IVSd and IVPWd measurements are used to determine left ventricular hypertrophy, which is the thickening of the muscle of the left ventricle. LV hypertrophy is a marker for heart disease. In general, a measurement of 1.1-1.3 cm indicates mild hypertrophy, 1.4-1.6 cm indicates moderate hypertrophy, and 1.7 cm or more indicates severe hypertrophy.
Forkortelser - LVPWd og LWPWs
Left ventricular posterior wall end diastole and end systole. The normal range is 0.6-1.1 cm.
The IVSd and IVPWd measurements are used to determine left ventricular hypertrophy, which is the thickening of the muscle of the left ventricle. LV hypertrophy is a marker for heart disease. In general, a measurement of 1.1-1.3 cm indicates mild hypertrophy, 1.4-1.6 cm indicates moderate hypertrophy, and 1.7 cm or more indicates severe hypertrophy.
Forkortelser - LVOT
2D parasternal long-axis view † † Zoom mode † † Adjust gain to optimize the blood tissue interface †
Inner edge to inner edge
Mid-systole
Parallel and adjacent to the aortic valve or at the site of velocity measurement (see text)
DIameter is used to calculate a circular CSA
Forkortelser - RVAWd
Right ventricular anterior wall end diastole diameter
Measured in PSLX, M-mode.
When right ventricular anterior wall thickness was more than 4.0 mm, pulmonary hypertension was detected, with a sensitivity of 97.5% and a specificity of 90.9%. (-> Hjelpe til å skille LE fra cor pulmonale)
Forkortelser - EPSS
E-point septal separation
The distance from the anterior mitral valve leafleft and the ventricular septum in early diastole.
The measurement is made in m-mode and is simply the closest the mitral valve gets to the septum in the cardiac cycle. In early diastole, the anterior mitral valve should approach or even touch the septum. In SHF, the ballooning heart with increased preload will pull valve away from the septum.
Like the LVEDD, the EPSS is a simple linear m-mode measurement obtained from the parasternal long axis view.
EPSS of >7mm is thought to be an indication of poor LV function. Some use 1cm as the mark to increase their sensitivity for low ejection fraction. So, you can see that it should be a good indicator of LV function.
Forkortelser - AVA
Aortic valve area
Calculated based on
- LVOT from PLAX
- LVOT velocity and/or VTI from the 5-chamber or apical long axis view
- The velocity of VTI at the aortic valve from the 5 chamber or apical long axis view
EPSS - Values
a. Normal
b. Left ventricular dysfunction
c. Severe left ventricular dysfunction
a. < 6 mm
b. > 7 mm
c. > 13 mm
EPSS can reliably estiamte left ventricular function in patients with aortic stenosis, but is usually misleading in patients with … (2)
- Significant MS
- Significant AR
Fractional shortening - How to
Measure left ventricle during diastole and systole. Measure left ventricular end-diastolic diameter (LVEDD) and LVESD with M-mode at the level of the papillary muscles at PSLX or PSSX.
(FS) = (LVEDD-LVESD)/LVEDD
(Measure LVEDD and LVESD at internal diameter)
Fractional shortening (FS)
a. Normal value, correspond to which EF%
b. Severe left ventricular dysfunction, correspond to which EF%
a. >25% (= >55%)
b. < 15% (= <30%)
Fractional shortening (FS) - Limitations for estimating EF
- RWMAs
- Oddly shaped ventricles
- Inaccurate if the M-mode cursor is not exactly perpendicualr to the septum and posterior wall
Patients with significant MR may have a hypercontractile LV bu a very low CO, and patients with dilated cardiomyopathy may have a good SV despite a low EF. When these clinical conditions are known or suspecte, it may be reasonable to correlate left ventricular EF with measurements of stroke volume. Which two measurements are necessary for this
- Area of LVOT
- Velocity time integral (VTI) of the flow through the aortic valve during systole
Left ventricular EF may not be a good indicator of cardiac output in patients with (4)
- AS
- MR
- Concentric left ventricular hypertrophy (LVH)
- Isolated left ventricular diastolic dysfunction (Make up 50% of patients with overt CHF)
Left atrial enlargement - Causes
- Left ventricular diastolic dysfunction (Most common)
- Volume overload from valvular regurgitation
- High output states like chronic anemia
Left atrial enlargement
a. Normal value
b. How to measure
a. < 4 cm / Significantly larger than the proximal aortic diameter
b. End-systolic atrial diameter (internal) in PSLX
Findings with LVH
- LV internal chamber diameter > 55-60 mm
- Wall thickness in end-diastole > 12 mm
Sonographic predictors of hypovolemia with fluid responsiveness (5)
- IVC size and respiratory changes
- Changes in cardiac output with respiratory cycle or passive leg raise
- Hyperdynamic cardiac function
- Small left ventricular end-diastolic area
- left ventricular systolic collapse
Hypovolemia - Findings of IVC with
a. Low CVP pressure (0-5 mmHg)
b. High CVP pressure (>15 mmHg)
a. IVC size < 2 cm with > 50% collapse on inspiration/sniff test
b. IVC size > 2 cm with no collapse on inspiration/sniff test and dilated hepatic vein
(The inbetween is less accurate)
(Collapse > 50% indicate pressure < 10 mmHg)
(Say in text < 1 cm is compatible with hypovolemia)
IVC size and collapsibility - May be misleading in ..
- COPD, right heart failure or other causes of chronically elevated RA pressure
IVC size in children, which ratio correlate with low CVP
Equal to or more than the aortic diameter and an IVC/aorta ratio of equal to or less than 0.8 correlates with low CVP
Acute dyspnea - IVC finding which is 96% specific for acute heart failure
IVC collapsibility < 15% and an IVC/aorta ratio > 1.2
Children - Evaluation for dehydration. AN IVC/aorta ratio of … has been found to be a relatively good indicator of significant dehydration requiring IV rehydration (Sensitivity 86%, specificity 56%)
< 0.8
Definition of a hyperdynamic left ventricle
Near or complte obliteration of the left ventricular cavity, meaning that the endocardial surfaces of the septum and posterior wall come in close contact with each other.
‘Kissing papillary muscle sign’ - What, significance
Papillary muscles touching in PSSX.
100% senssitive for detecting hypovolemia, but only 30% specific for predicting volume responsiveness
How to use ventricular volume to predict hypovolemia
In parasternal short-axis over papillary muscles measure the cross-sectional area in end-diastole by tracing the endocardial border
< 10 cm^2 generally indicates hypovolemia
Top 2 causes of acute MR
- Rupture of chordae tendinae or papillary muscles secondary to AMI (More probably with inferior wall MI with involvement of the RCA)
- Infective endocarditis
Mitral valve
a. Where to visualize the two leaflets
b. Findings if ruptured
a. PSLX and PSSX
b. Clearly visible flail leaflet if the entire papillary muscle is ruptured
(Normal valve leaflets should appear thin, produce uniform echoes, and be unrestricted in their motion. Thickened, immobile valve leaflets are often associated with regurgitation)
Color flow doppler is the key to detecting regurgitation and the easiest way to determine the sverity of regurgitation. Mitral regurgitation is severe if …
.. the regurgitant jet area fills > 40% of the left atrial area
AR is an acute process in about 20% of cases and most commonly caused by … (2)
- Infective endocarditis
- Proximal aortic dissection
AR - Patients with chronic AR are more likely to have obvious abnormalities such as …
- Thickened and immobile valve leaflets
- LV enlargement
(Those with acute AR may have a normal-sized left ventricle and thin valve leaflets on 2D imaging.)
Aortic valve leaflets
a. Normal leaflets are best visualized in which view
b. Normal leaflets should appear
a. PSLX
b. Thin, produce uniform echoes, be unrestricted in their motion, coapt in the center of the aortic root during diastole and snap open and lie parallel to the aortic wall during systole
AR
a. Screening test
b. Severe aortic regurgitation
a. Color flow doppler in A5C, measurement of the maximal proximal jet width and its ratio to the LVOT diameter
b. > 65% is diagnostic of severe AR
Where to measure LVOT diameter
In PSLX in mid-systole, from the white-black interface of the septal endocardium to the anterior mitral leaflet, parallel to the aortic valve plane and within 5-10 mm from the valve orifice
Signs of aortic dissection on TTE (4)
- Pericardial effusion (Sign of imminent mortality without surgical intervention)
- Presence of ascending aorta involvement
- Presence of descending aorta involvement
- Presence of abdominal aorta involvement
Cardiac windows - Which views are best when the patient exhales and which are best when the patient inhales
Exhale -> parasternal and apical
Inhale -> Subcostal