Echocardiography I Flashcards
(126 cards)
1
Q
What technique is most commonly performed for an echocardiogram examination?
A
Transthoracic echocardiography. However, the use of transesophageal echocardiography via a specialized endoscopic mounted probe is on the rise, but is hindered by limitations (e.g., general anesthesia).
2
Q
What are the three (3) most commonly used imaging modalities for the routine echocardiographic examination?
A
(1) 2-dimensional (2DE) echocardiography;
(2) motion-mode echocardiography (M-mode);
(3) Doppler echocardiography, which includes color Doppler imaging (CDI) and spectral Doppler (e.g., pulsed wave and continuous wave) imaging.
3
Q
Real-time imaging (2DE or brightness (B)-mode) serves as the foundation of the echocardiographic examination. Why?
A
2D echocardiography readily quantifies cardiac SIZE and FUNCTION, and further identifies most clinically significant MORPHOLOGIC ABNORMALITIES.
4
Q
When obtaining a certain image, what is the standard nomenclature assigned to the typical transthoracic echocardiogram examination?
A
- Location (right or left parasternal, apical, subcostal/subxiphoid).
- Plane (Long-axis [Sagittal], short-axis [transverse], apical or angled)
- Number of chambers imaged [2-, 3-, 4- or 5]
- Tomographic characteristics [hybrid off-angled view of a main structure - ie. left auricular view in cats].
Example: Right Parasternal Long-Axis 4-chamber
5
Q
Define M-mode echocardiography.
A
M-mode is a one-dimensional (“ice-pick”) graphic display of cardiac motion over time.
M-mode displays time (in seconds) in the horizontal plane and depth (in cm) from the transducer face along the vertical axis. The mode processes a high sampling rate, typically greater than 1,000 pulses per second.
6
Q
What are at least three (3) imaging planes for performing M-mode during an echocardiogram examination?
A
- left ventricular cavity and wall motion at the level of the chordae tendinae or “high” papillary muscles along its minor (acquired RP Sx and RP 4-ch). - IVSd, LVFWd, LVIDd, IVSs, LVFWs, LVIDs
- mitral wave motion at the valve tips, capturing peak diastolic excursion of the anterior (cranial) mitral valve leaflet. - EPSS
- ventricular (right +/- left ventricular) annular motion along its major axis (apical-to-basilar plane or longitudinal shortening) – TAPSE/MAPSE.
- NOT INCLUDED Left atrium-to-aortic ratio (RP Lx5Ch, RP SxLAAo)
7
Q
What are at least four (4) common reasons to warrant an echocardiographic examination?
A
- Heart murmur or any other abnormality (arrhythmia, extra/abnormal heart sound) identified during cardiac auscultation.
- Clinical signs associated with cardiovascular disease (cough, dyspnea, tachypnea, abdominal distension, syncopal/collapse, exercise intolerance).
- High risk breeds (Doberman pinscher, Cavalier King Charles Spaniel)
- Suitability for breeding
8
Q
What diagnostic information can an interpreter extract from a complete echocardiogram examination? List 6.
A
- Cardiac morphology and pathology.
- Cardiac size and motion.
- Systolic function of the atria and ventricles.
- Diastolic function.
- Valvular function.
- Hemodynamics.
9
Q
Name some limitations for echocardiography? List 6.
A
- Individual-based limitations.
- Echocardiography cannot provide a definitive diagnosis of congestive heart failure – this requires integration of clinical knowledge with additional imaging of the thorax (to assess for cardiogenic pulmonary edema, pleural effusion, or both) and abdomen (to assess for cardiogenic abdominal effusion).
- Echocardiography is limited in its ability to provide tissue-specific information. For example, it cannot provide reliable information regarding the amount of cardiac fibrosis or inflammation.
- Echocardiography is limited in its ability to view the great vessels, particularly more distal aspects.
- Echocardiography cannot predict anesthetic risk in and of itself. This requires integration of clinical knowledge and should involve the attending clinician, the echocardiographic findings and diagnosis, and anaesthetist/anaesthesiologist.
- Physiologic variation, day-to-day variability, and artifacts can be misinterpreted for evidence of disease.
10
Q
Describe the transducers utilized in cardiac imaging?
A
Cardiac imaging transducers (probes) have a smaller “footprint” (red rectangle) useful for acoustic windows within rib spaces (intercostal). They also emit sound waves as a sector compared to the wider (and slower) format used for abdominal (linear or convex) scanning. Tiny dogs and cats are usually scanned with > 7 MHz transducers and larger/giant dogs are scanned with lower frequency transducers (4 MHz).
11
Q
What is Dynamic Range and Grayscale Processing?
A
Dynamic range impacts the contrast and shades of grey. Many systems have a compression (dynamic range) and post-processing options for grayscale that the operator and interpreter should become familiar with and adjust as necessary to optimise imaging.
12
Q
Define temporal resolution and what is required of it during a cardiac ultrasound examination?
A
Temporal resolution is characterized by motion over time. Cardiac imaging demands a relatively high temporal resolution.
Adequate temporal resolution permits slow motion review of each captured frame from stored video loops. This is especially important during periods of rapid heart rates where subtle motion abnormalities could be missed. Modern systems commonly record 2DE videos superior to 150 frames/second.
13
Q
How can the sonographer/interpreter increase temporal resolution, and list two (2) ways to do so?
A
Increase in temporal resolution is directly proportional to increasing frame rate.
- Narrow the cardiac sector visualization plane.
- Reduce depth of field.
14
Q
Which of the following statements are correct? Select all that apply.
A. Temporal resolution is quantified by acquisition frame rate.
B. Higher frequency transducers permit better image resolution without sacrifice tissue penetration.
C. During scanning, temporal resolution can usually be increased up to a point by increasing the frame rate within the system control settings.
A
Answer: A & C.
A. Temporal resolution is quantified by acquisition frame rate.
C. During scanning, temporal resolution can usually be increased up to a point by increasing the frame rate within the system control settings.
15
Q
When adjusting sweep speed for M-mode settings, what would be an ideal speed for cats (high heart rate)?
A
Sweep speed should be adjusted as needed. More cardiac cycles can be captured at slower sweep speeds and vice versa.
Faster sweep speeds (i.e., 100 mm/sec or more) are ideal for faster heart rates (e.g., cats) and for more accurate timing of cardiac events.
16
Q
2D (B-mode) echocardiography is capable of all of the following EXCEPT
1. Assessment of cardiac size
2. Assessment of systolic (pumping) function
3. Identifying valvular pathology
4. Assessment of blood flow in specific regions
A
Assessment of blood flow in specific regions
This is evaluated primarily through Doppler echocardiograpy
17
Q
Which of the following is a good indication for an echocardiographic examination?
1. To definitively diagnose congestive heart failure
2. To accurately predict anesthetic risk
3. To determine the cause of a heart murmur
4. To determine the amount of cardiac fibrosis
A
To determine the cause of a heart murmur
All of the other options (e.g., diagnosing CHF, predicting anesthetic risk or cardiac fibrosis) cannot be determined by echocardiography.
18
Q
Which of the following would help improve temporal resolution and increase frame rate?
1. Increasing the depth of field
2. Increasing the overall 2D gain
3. Narrowing the sector width/angle
4. Increasing the far field Time-gain-compensation (TGC)
A
Narrowing the sector width/angle
19
Q
What are the initial considerations prior to performing the exam that will help improve the quality of the examination?
A
- Indications for and goals of the echocardiographic examination.
- Respiratory status/stability of the patient.
- Compliance, willingness to tolerate manual restraint.
20
Q
What are some indications for the usage of sedatives prior to the echocardiogram examination?
A
- Refuse to lie still;
- Appear overtly stressed or anxious;
- Are aggressive or are considered to be potentially harmful.
21
Q
What are some common drugs utilized for light sedation?
A
- Butorphanol +/- acepromazine
- Buprenorphine +/- acepromazine
22
Q
What are some common drugs utilized for heavy sedation?
A
- Butorphanol + acepromazine [moderate sedation]
- Alfaxalone [heavy sedation]
- Alpha-2 agonists (e.g., dexmedetomidine) [heavy sedation]
Caution! Alpha-2 agonists will increase afterload and reduce systolic (pump) function. Hence, alpha-2 agonists are commonly avoided, especially in patient with known cardiovascular disease.
Avoid acepromazine in hypotensive animals!
23
Q
Echocardiographic images are conventionally displayed on the viewing screen with cranial and dorsal structures to the viewer’s right as they face the screen. Exceptions include which of the following?
A. Left Apical 4-Chamber view
B. Left Cranial parasternal
A
Left Apical 4-Chamber view
24
Q
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
A
Right Parasternal Long Axis 4-Chamber View (RPLx4Ch)
Patient positioning: Right lateral recumbency.
Transducer placement: Palpate the precordial impulse and place the transducer perpendicular to the long-axis of the animal. This is typically the 4th or 5th intercostal space, dorsal to the sternum, ventral to the costochondral junction.
Primary focus: Left atrium, mitral valve anatomy, and LV inlet.
25
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Right Parasternal Long Axis 5-Chamber View (RPLx5Ch)
Patient positioning: Right lateral recumbency.
Transducer placement: Slight counter-clockwise rotation often with cranial angulation.
Primary focus: Left ventricular outflow tract, anterior mitral valve leaflet.
26
**Which of the following statements are true? Select all that apply.**
A. The patient should be positioned in lateral recumbency when we want to obtain a right parasternal long-axis image.
B. It is common to visualize the anterior cranial papillary muscle with right parasternal long-axis 5-chamber (left ventricular outflow) view.
ANSWER: A & B.
A. The patient should be positioned in lateral recumbency when we want to obtain a right parasternal long-axis image.
B. It is common to visualise the anterior cranial papillary muscle with right parasternal long-axis 5-chamber (left ventricular outflow) view.
27
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Right Parasternal Short Axis High Papillary Muscle View ("Mushroom")
Patient positioning: Right lateral recumbency.
Transducer movement from previous position: Approximately 90-degree counter-clockwise rotation; approximately orthogonal to the right parasternal long-axis views.
Primary focus: Transverse image and motion analysis of the left ventricle, which resembles a mushroom.
28
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Right Parasternal Short Axis Mitral Valve view ("Fishmouth")
Patient positioning: Right lateral recumbency.
Transducer movement from the previous position: Slight dorsal angulation.
Primary focus: Appearance and motion of the mitral valve leaflets, which resembles a fish mouth.
29
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Right Parasternal Short Axis Basilar view, Aortic root level ("LA/Ao")
Patient positioning: Right lateral recumbency.
Transducer movement from previous position: Slight dorsal and cranial angulation.
Primary focus: Appearance of the aortic root and valve cusps; visualisation the LA size relative to the aortic root.
30
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Right parasternal short-axis basilar view, right ventricular outflow tract
Patient positioning: Right lateral recumbency.
Transducer movement from previous position: Steep dorsal and cranial angulation aiming the beam toward the patient’s left shoulder.
Primary focus: Right ventricular outflow tract: pulmonary valve, pulmonary artery and bifurcation.
31
**Which of the following is an appropriate drug used for light sedation to help facilitate an echocardiographic examination?**
A. Alfaxalone
B. Butorphanol
C. Dexmedetomidine
D. Ketamine
B. Butorphanol
32
**Which anatomic structure should not be visualized from a right parasternal long-axis 4-chamber view?**
A. Right atrium
B. Left atrium
C. Aortic valve
D. Mitral valve
C. Aortic Valve
33
**Which anatomic structure should not be visualized from a right parasternal short-axis basilar view, aortic valve level? **
A. Left atrium
B. Left auricle
C. Mitral valve
D. Tricuspid valve
C. Mitral valve
34
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Subxiphoid / Subcostal view, LVOT
Patient positioning: Right lateral recumbency.
Transducer movement from previous position: Reposition the transducer just caudal to the xiphoid process. Following gentle pressure into the abdomen, perform cranial angulation.
Primary focus: Parallel alignment with the blood flow in the proximal aorta.
35
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Subxiphoid / Subcostal view, CVC
Patient positioning: Right lateral recumbency.
Transducer movement from previous position: Dorsal angulation with varying degrees of movement toward and away to locate the caudal vena cava as it passes through the diaphragm.
Primary focus: Caudal vena cava at the level of the diaphragm (sagittal plane), visualization of the hepatic vein.
36
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Left Apical 4-Chamber View.
Patient positioning: Left lateral recumbency.
Transducer movement from previous position: The transducer is repositioned caudoventrally (along the sternum) and slightly caudal to the palpable left apical precordial impulse. One can start by placing the transducer perpendicular to the body wall where the left apical precordial impulse is palpated. This usually shows the liver and requires steep cranial angulation of the ultrasound beam while slowly moving cranially until the heart appears.
Primary focus: Left ventricular inlet; Left ventricle, mitral valve, and left atrium.
37
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Modified Left Apical 4-Chamber View (Optimized for RV and RA):
Patient positioning: Left lateral recumbency.
Transducer movement from previous position: This typically requires moving the transducer one intercostal space cranially with some caudal angulation.
Primary focus: The right heart, specifically the right ventricular inlet.
38
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Left Apical 5-Chamber View
Patient positioning: Left lateral recumbency.
Transducer movement from previous position: Slight cranial angulation and counter-clockwise rotation.
Primary focus: Left ventricular outflow tract including the aortic valve and proximal aorta.
39
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Left Cranial View, LVOT
Patient positioning: Left lateral recumbency.
Transducer movement from previous position: The transducer is rotated approximately 90 degrees cranially (with the reference mark directed toward the patient’s head). The ultrasound beam is centred on the aortic valve and the long-axis of the ascending aorta. This view represents “home base” for left cranial parasternal imaging.
Primary focus: Left ventricular outflow tract, especially the aortic valve and ascending aorta.
**This is an excellent view to look for a subvalvular ridge of tissue often seen in dogs with subaortic stenosis.
40
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Left Cranial View, R-Auricle (dogs)
Patient positioning: Left lateral recumbency.
Transducer movement from previous position: Using the left cranial view optimised for the aorta in long-axis as a reference and without moving the transducer position, the cable is moved (“dropped”) away from the operator to bring the right atrium and, with fine-plain angulation, the right auricle into view.
Primary focus: Right Auricle.
**This is the recommended view to look for cardiac tumours near or on the right auricle (e.g., cardiac hemangiosarcoma). This view is especially important in dogs with pericardial effusion.
41
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Left Cranial View, Pulmonary Artery
Patient positioning: Left lateral recumbency.
Transducer movement from previous position: Using the left cranial view optimised for the aorta in long-axis as a reference and without moving the transducer position, the cable is moved toward the operator (bringing the cable upward) to optimise the right ventricular outflow tract.
Primary focus: Right ventricular outflow tract, especially the pulmonary valve and proximal pulmonary artery.
42
DESCRIBE THE POSTION (NAME, POSITION, PLACEMENT, AND FOCUS)
Left Cranial View, Left Auricle (Cats)
Patient positioning: Left lateral recumbency.
Transducer movement from previous position: The left auricle is seen while fanning the transducer between the pulmonary and tricuspid valve in the transverse left cranial imaging plane. A slightly more dorsal transducer position might be necessary.
Primary focus: The ultrasound beam is aligned to the opening of the left auricle with the body of the left atrium (LA proper) in the far-field.
43
What measurement errors can potentially lead to a misdiagnosis of LV wall thickening/hypertrophy, particularly in cats?
A. Sampling of the one or both of the papillary muscles. They can blend into the LVFW
B. Including the septal tricuspid papillary muscle;
C. Including a LV false tendon (sometimes also referred to as a moderator band).
44
**Which 2D echocardiographic imaging plane is not necessary to acquire in dogs but is important to acquire and evaluate in cats?**
A. Left cranial parasternal imaging of the pulmonary artery
B. Left cranial parasternal imaging of the left auricle
C. Left apical 5-chamber view
D. Subcostal/subxiphoid view of the left ventricular outflow tract
B. Left cranial parasternal imaging of the left auricle
45
**Which 2D echocardiographic imaging plane is not necessary to acquire in cats but is important to acquire and evaluate in dogs?**
A. Left cranial parasternal imaging of the pulmonary artery
B. Left cranial parasternal imaging of the left ventricular outflow tract
C. Left apical 5-chamber view
D. Subcostal/subxiphoid view of the left ventricular outflow tract
D. Subcostal/subxiphoid view of the left ventricular outflow tract
46
**Is the following statement true or false?**
A M-mode image of the left ventricle (minor axis) can be acquired from a right parasternal long-axis or right parasternal short-axis projection.
True
False
True
47
Measurements of cardiac chamber size (and function) can possess a relatively high degree of variability to due several factors.
Provide some physiologic and non-physiologic limitations.
Physiologic Factors:
(1) Drugs affecting the CV system;
(2) Loading (preload/afterload) conditions;
(3) Heart Rate and Rhythm;
(4) Body size;
(5) Plasma volume/hydration status;
(6) Body Type;
(7) Autonomic tone;
(8) Breed (somatotype);
(9) Body Condition;
(10) Species
Non-Physiologic Factors: (1) Operator, (2) Ultrasound Equipment, (3) Acquisition and measurement error
48
List 3 primary ways to QUANTIFY cardiac chamber size?
1. **Linear** measurements of the length of the major or minor axis of a chamber (M-Mode or 2D echocardiography)
2. **Area** measurement of a chamber (2DE) - SMOD
3. **Volume** estimates of a chamber using a combination of 1 and 2 (2DE)
49
What patient condition variable primarily influences cardiac chamber size the most in a healthy animal?
Body Size. The range of body size encountered in dogs is particularly expansive.
50
List two (2) popular methods to index cardiac measurements to body size, providing advantages and disadvantages to both.
(1) Normalizing Body Weight using ALLOMETRIC SCALING.
A - Body weight (equivalent to a volume) does NOT exhibit a linear relationship with LVIDd (a length). Therefore, length needs to be “scaled” to body weight1/3 (because length3 = volume) due to its nonlinear relationship. LVIDDN (<1.65) = LVIDD (cm) / BWkg0.3
D - This method is **less accurate if the animal is very skinny (under conditioned) or obese (over conditioned)**.
(2) Normalizing Body Weight using Aortic Ratios (Sx and Lx)
Aortic Root (RPSxBasilar, LA/Ao) - This measurement is performed just after aortic valve closing (early diastole)
Aortic Root (RPLx5Ch) This measurement is performed in early to mid-systole (just after valve opening) at the level of the valve hinge points between the maximally opened aortic valve cusps.
LVIDDN (<2.6) = LVIDD (cm)/ AoLx
51
What are some general recommendations to judge cardiac chamber size?
1. Clinical context (**physiologic v. non-physiologic** - refer to previous card)
2. **Repeated chamber size measurements** (e.g., multiple times, ideally by the same sonographer, and averaged)
3. Prioritize **breed specific measurements** over multi-breed reference intervals.
4. Prioritize intervals that **normalize**
5. Prioritize consulting **reference intervals that have been derived from large populations** in literature.
6. Avoid relying on single linear measurements. **Use of multiple measurements** (at least two), particularly from multiple imaging planes.
7. **Don't ignore your subjective assessment but don't rely on this solely for clinical decisions**.
52
**Which of the following has the largest influence of cardiac chamber size in dogs?**
A. Heart rate
B. Body size
C. Sex
D. Plasma volume
B. Body Size
53
**Which of the following would be the preferred method to index (normalize) a linear cardiac chamber size measurement to body size in an obese dog?**
A. Normalize to body weight (in kg) using allometric scaling
B Index to the aorta using an aortic ratio
C. There is no need to index to body size
D. Normalize to body surface area (BSA)
Answer: Index to the aorta using an aortic ratio (For over- and underconditioned patients)
To note, normalizing to body weight (in kg) using allometric scaling should only be utilized for IDEAL patient size.
54
**Measurements of the aortic valve annulus in long-axis (right parasternal long-axis 5-chamber view) are smaller than measurements of the aortic root in short-axis (right parasternal short-axis basilar view)?**
True
False
True.
55
What are some diseases that chronically increase left atrial pressure, volume or both subsequently causing LA dilation?
Myxomatous mitral valve disease (dogs);
Hypertrophic cardiomyopathy (cats);
Dilated cardiomyopathy (dogs);
Other cardiomyopathies;
Ventricular septal defect;
Patent ductus arteriosus;
Mitral valve dysplasia (malformation);
Chronic bradyarrhythmias;
Tachyarrhythmias with concurrent LV dysfunction;
High output, fluid retentive states secondary to systemic disease (e.g., anaemia, hyperthyroidism).
56
What is the appropriate timing (during a cardiac cycle) to measurement atrial size?
Most atrial size assessments are performed at maximum volume i.e., at end (ventricular)-systole – just prior to mitral valve opening. This timing coincides with the end of the T-wave on the ECG tracing.
57
In the RPLx4Ch view, what are some sonographic features to describe LA dilation?
1. The interatrial septum bows towards the right atrium
2. Dilation of the adjacent pulmonary vein
3. LA appears more spherical
58
Describe the linear measurement of the LA (LAmax) from the RPLx4Ch view?
This measurement is performed mid-chamber (bisecting the long-axis atrial area) at end-systole. The measurement extends from the inner region of the fossa ovale (mid-atrial septum) to the internal reflection of the bright (hyperechoic) pericardium in the far-field, approximately parallel to the mitral annulus (dotted white line).
This measurement avoids incorporating a pulmonary vein (compared to short-axis measurement discussed below) but does occasionally present challenges in identifying a distinct internal border in the far-field.
59
What are the two methods for indexing the LA long-axis measurement to body size?
1. An **allometric equation**: normalised LA in long-axis (nLA Lx) = LA Lx (in cm)/body weight (in kg)0.3. - ideally in IDEAL body score patients.
2. **Indexed to the long-axis aortic valve annulus measurement** discussed in the previous lesson (LA/Ao Lx). -- ideally for over- and underconditioned patients.
---
For dogs, nLA Lx >1.6 (cm/kg0.3) and LA/Ao Lx >2.6 are highly suggestive of LA enlargement.
For cats, LA Lx >1.6 cm (16 mm) is highly suggestive of LA enlargement.
60
Describe the linear measurement of the LA from the RPSx Basilar view, Aortic root?
The measurement is taken in **early diastole**. This measurement is made from the internal border of the LA (adjacent to the aortic root) extending from and parallel to the commissure between the left and non-coronary cusp (i.e., continued along the trajectory of the aortic root measurement [dotted while line]) to the internal border of the distant LA wall in the far-field, often near a pulmonary venous ostium. Care should be taken to avoid including a pulmonary vein in the measurement.
If a pulmonary vein(s) enters the LA at the desired measurement point, the line can be drawn to what is considered to be an extrapolation of the atrial border (dotted yellow line) as shown in the image below. This is not uncommon in dogs but rarely necessary in cats.
For dogs, LA/Ao Sx >1.6 has been used as a cut-off for LA enlargement. However, emerging evidence from multiple large studies of healthy dogs have suggested the >1.7 is a better delineator for normal vs abnormal.
For cats, LA/Ao Sx >1.6 cm is suggestive of LA enlargement
61
Can you acquire an LA/Ao using M-mode?
The LA/Ao Sx can also be acquired with M-mode. However, it is not recommended because the cursor crosses the junction of the body of the LA and left auricle, which underestimates maximum LA dimensions, especially in dogs.
62
What views are common to acquire left atrial volume?
Left atrial volume estimates are also possible using Simpson’s method of discs (SMOD) from either the right parasternal long-axis 4-chamber view or left apical 4-chamber view. The internal border of the LA is traced at end-systole (just prior to mitral valve opening.
To index to body size, both LA volume estimates can simply be divided by body weight (in kg).
For dogs, LAV_RPLx >1.6 mL/kg is suggestive of LA enlargement and LAV_LAP4Ch >1.1 mL/kg is suggestive of LA enlargement.
63
What is a major recommendations for performing LA/Ao?
**Multiple plane measurements**. Performing both the LA/Ao Sx AND the LA Lx (which can be indexed to body size by either method – nLA Lx or LA/Ao Lx) measurements are strongly advised. This increases confidence (i.e., specificity) that the patient truly has LA enlargement if both measurements are above the aforementioned reference intervals. If only one LA size measurement is increased, the patient can be said to have equivocal (or “borderline”) LA enlargement.
64
**Which of the following is an advantage of the linear long-axis measurement of the left atrium (from the right parasternal long-axis 4-chamber view)?**
A. A distinct internal border of the left atrium in the far-field is easily identified.
B. This measurement incorporates a pulmonary vein.
C. The aorta is visualized in the same view as a size frame of reference.
D. This measurement avoids incorporating a pulmonary vein.
This measurement avoids incorporating a pulmonary vein.
As opposed to the RPSxBasilar view, the pulmonary vein does not have to interfere with the measurement, if distended.
65
**Which of the following is an advantage of the linear short-axis measurement of the left atrium (from the right parasternal short-axis basilar view)?**
A. This measurement has been shown to be highly reproducible.
B. This measurement incorporates a pulmonary vein.
C. The aorta is visualised in the same view as a size frame of reference
D. This measurement avoids incorporating a pulmonary vein.
The aorta is visualised in the same view as a size frame of reference
66
**Volume estimates of left atrial size are more likely to detect left atrial enlargement (i.e., more sensitive) compared to a linear measurement.**
True or false?
True
False
True
67
Describe various cardiac pathologies that may contribute to as a **simple ventricular dilation (Dilatation)**.
Acute volume overload.
Severe, end-stage DCM
68
Describe various cardiac pathologies that may contribute to as a **dilation with normal wall thickness (Eccentric hypertrophy)**.
Valvular regurgitations (e.g., mitral valve regurgitation from myxomatous mitral valve disease or mitral valve dysplasia)
Left-to-right shunts (e.g., patent ductus arteriosus, ventricular septal defects)
Compensated dilated cardiomyopathy
Chronic bradyarrhythmias
69
Describe various cardiac pathologies that may contribute to as **wall thickening at the expense of the ventricular lumen (concentric hypertrophy)**.
Hypertrophic cardiomyopathy
(Sub)aortic stenosis
Systemic hypertension
70
Describe various cardiac pathologies that may contribute to as **concentric hypertrophy WITH chamber dilatation (mixed hypertrophy)**
(Sub)aortic stenosis with aortic regurgitation
Hypertrophy cardiomyopathy or (Sub)aortic stenosis with myocardial failure
71
What is the appropriate timing (in a cardiac cycle) to perform measurements of the left ventricular chamber?
Essentially, all ventricular size assessments are performed at **end-diastole** coinciding with maximum ventricular size, immediately following atrioventricular valve closure. If the view does not permit visualization of an atrioventricular valve, end-diastole can be defined by maximum chamber dimension or by the Q wave or beginning of the R wave on the ECG tracing.
72
What are some points to keep in mind when measuring a cats left ventricular walls? Discuss these features pertaining to both the interventricular septum and posterior wall.
For the interventricular septum:
- Use a leading edge-to-trailing edge technique (endocardium of the RV to endocardium of the LV);
- Avoid including a septal right ventricular papillary muscle
-Avoid including the insertion of a false tendon as shown in the figure below (of a different cat). In this image, the wall thickness measurement labelled #3 should be discarded. Wall thickness measurement labelled #1 is acceptable.
For the posterior wall:
- Use a leading edge-to-leading edge technique (exclude the pericardium, which is always bright/hyperechoic);
- Avoid measuring the posterior papillary muscle (PPM) and chordae tendineae (CT).
73
How should you measure the left ventricle from the RPSx High Papillary Muscle view in M-mode?
By convention, these measurements are performed using the leading edge-to-leading edge technique. This means measurements are made from the “leading” or top edge of one structure to the leading edge of the next structure as shown.
Analogous measurements can and should be performed from frozen 2D echocardiographic images if the M-mode cursor is misaligned.
74
From the right parasternal short-axis MV view, how do you measure the E-point to septal separation (EPSS)?
The distance between the maximum opening of the anterior mitral valve leaflet (E-point) to the interventricular septum increases as a result of chamber dilation secondary to systolic dysfunction (e.g., dilated cardiomyopathy). In other words, this measurement does not solely quantitate chamber size; it is also indicative of LV systolic dysfunction.
Be aware, false positives (i.e., false increases) in EPSS are possible with:
- Off-angle imaging;
- Mitral valve stenosis;
- Eccentric aortic valve insufficiency.
75
Describe how you preferably measure the left ventricle in a cat?
Frozen 2D measurements are advised for routine assessment (as demonstrated in the figure), particularly in cats with suspected wall thickening. Observing the 2D cine/video loop, preferably in slow motion, and then performing measurements from the frozen 2D image(s), can help delineate structures and avoid measurement errors (e.g., false positive increases in wall thickness).
Translational motion and papillary muscle hypertrophy can present challenges with LV M-mode measurements. Note, the less discriminate borders shown in the M-mode above from a cat with hypertrophic cardiomyopathy.
76
What formulas are used indexing left ventricular chamber size and wall thickness to body size, in dogs? Name 5.
LVIDd (cm) / body weight (kg)0.3 – preferred if there is aortic pathology
LVIDd (cm) / AoLx (cm) – preferred if the dog is overtly over- or underweight
IVSd (cm) / body weight (kg)0.3
LVFWd (cm) / body weight (kg)0.3
EDV (mL) / body weight (kg)
77
What preferable guidelines should be followed when performing measurements of left ventricular chamber size and wall thickness should be performed for all echocardiographic examinations, in dogs?
1. **breed-specific reference intervals** should always be consulted and prioritised, if available
2. Use of **orthogonal measurements** of LVIDd from both long-axis and short-axis are also strongly advised. Long-axis measurements might underestimate LV chamber size and short-axis measurements have a tendency to overestimate chamber size.
3. **End-diastolic volume estimates (e.g., SMOD) ** are more likely to detect mild LV chamber enlargement and are, in theory, more sensitive to changes in LV size over time. However, they are more time consuming, technically demanding, and less reproducible relative to linear measurements.
4. **Volume estimates are typically prioritised for screening dogs for dilated cardiomyopathy** and some other clinical scenarios where documenting early changes in LV size
5. Wall thickness measurements in dogs are most commonly performed from the **short-axis M-mode** examination.
78
What preferable guideline should be followed when performing measurements of LV chamber size and wall thickness should be performed for all echocardiographic examinations, in cats.
1. **Breed-specific reference intervals** should also be consulted, particularly in breeds known to be predisposed to cardiomyopathies (e.g., Maine Coons) or breeds that are extremely small or large.
2. **End-diastolic LV wall thickness measurements** be measured from **2D** echocardiographic from both **short-axis and long-axis**, measuring the thickest part of the septum and free wall, while avoiding papillary muscles and false tendons
79
**Which of the following is the recommended method to index linear LV chamber size measurements (i.e., LVIDd) to body size if a dog is severely overweight?**
A. Normalize to body weight (kg)0.3 (allometric scaling)
B. Index to the diameter of the aortic valve annulus in long-axis (AoLx)
C. Index to the diameter of the aortic root in short-axis (AoSx)
D. Normalize to body weight (kg)
Index to the diameter of the aortic valve annulus in long-axis (AoLx)
80
**Which of the following could cause a false increase (false positive) in the E-point to septal separation (EPSS) measurement?**
A. Aortic valve stenosis
B. Mitral valve regurgitation
C. Aortic valve insufficiency
D. Dilated cardiomyopathy
Aortic valve insufficiency.
Other causes include mitral valvular stenosis and off-angle imaging.
81
**True or false, M-mode echocardiography is recommended for wall thickness measurements in cats? **
True
False
False.
A thickened papillary muscle and translational motion make it difficult to accurately measure the LV chamber using M-mode.
82
What echocardiographic value conventionally correlates to assessing systolic function?
Ejection fraction (volume).
Ejection fraction (%) = (stroke volume (EDV – ESV) / EDV) * 100
Stroke volume (ml) = end-diastolic volume (EDV) – end-systolic volume (ESV)
** Stroke volume = volume of blood pumped by the ventricle in one cardiac cycle
83
Aside from ejection fraction (volumetric measurement) to assess stroke volume/systolic function, what two other measurements can be utilized?
1. **Fractional shortening (linear)**. A surrogate of ejection fraction calculated using linear measurements instead of volumes. Left ventricular internal dimension at end-diastole (LVIDd) – left ventricular internal dimension at end-systole (LVIDs) / LVIDd over one cardiac cycle quantitated as a percent.
2. **Fractional area change (area)**. Another surrogate of ejection fraction calculated using area measurements instead of volumes. Left ventricular end-diastolic area (LVAd) – left ventricular end-systolic area (LVAs) / LVAd over one cardiac cycle quantitated as a percent.
84
Name nine (9) key factors that have an important influence to systolic ventricular function.
1. **Contractility (inotropy)** - degree of myofiber shortening independent of load. Influenced by the autonomic nervous system. **Directly proportional** to ejection fraction/systolic function (decreasing ESV).
2. **Preload (Diastolic wall stress)**. **Directly proportional** to systolic function/ejection fraction (increasing EDV).
3. **Afterload (Systolic wall stress)**. **Inversely proportional** to systolic function/ejection fraction (increasing ESV).
4. **Heart rate**. (Sinus tachycardia) increases systolic function, thereby impact EF% (and surrogates). Therefore, heart rate is **directly proportional** to systolic function, hence this is a compensatory mechanism in systolic dysfunction situations, such as DCM.
5. **Heart Rhythm**. Arrhythmias may influences systolic function (Afib, VPCs, etcs)
6. **Systemic disease** (e.g., endocrinopathies, sepsis);
7. **Hydration status**;
8. **Level of stress/anxiety** (sympathetic tone);
9. **Drugs, sedatives**
85
Aside from Ejection fraction (and its surrogates), what is an additional measurable metric to predict systolic function in dogs?
**End-systolic volume (ESV, or LVIDs)**.
This is conceptually valid and clinical value has been demonstrated, especially within the context of dilated cardiomyopathy. However, it should be indexed to body size – either body weight (kg) or body surface area (m2). If LVIDs is utilised, it also should be normalised to body weight using allometric scaling. Lastly, there are significant technical challenges associated with LVIDs when measured by M-mode related to dyssynchrony.
86
How do we obtain fractional shortening during an echocardiogram examination?
This is most commonly performed from the **M-mode examination of the LV**.
Analogous calculations of fractional shortening can be made using 2D echocardiography and are advised if the M-line alignment is suboptimal. 2D imaging is often the preferred approach for cats with wall thickening. Fractional shortening can also be acquired from right parasternal long-axis imaging planes.
87
What are some reasons for LV intraventricular desynchrony?
1. **Misdirection of the M-line (cursor)** – septal imaging is too dorsal in the subaortic region, which has limited motion relative to the mid-septum.
2. **Myocardial disease (e.g., Dilated cardiomyopathy)**.
3. **Arrhythmias**. Cardiac conduction disease secondary to left bundle branch block, which can be confirmed electrocardiographically. This causes a delay of electrical activation of the LV free wall, which subsequently delays LV free wall motion.
88
**Which of the following can contribute to reduced systolic (pump) function? **
A. Decreased afterload
B. Increased afterload
C. Post-extrasystolic potentiation after a premature ventricular complex (PVC)
D. Increased preload
Increased afterload.
EF% = (SV = EDV - ESV) / EDV x 100
Think about influences to ejection fraction/systolic function:
Contractility = ejection fraction/systolic function
Preload (diastolic wall stress) = ejection fraction/systolic function
Afterload (systolic wall stress) inversely proportional to EF/Systolic function.
Thereby, reducing systolic function has to be achieved through increasing afterload.
89
**Which of the following quantitates the percent change in blood volume leaving the ventricle in one cardiac cycle?**
A. Fractional shortening
B. Cardiac output
C. Ejection fraction
D. Stroke volume
Ejection fraction. Its the PERCENT change of VOLUME.
Fractional shortening is percent change but LINEAR.
Stoke volume is the DIFFERENCE between EDV and ESV
CO = SV x HR
90
**Measurements used for assessment of systolic function should be acquired and averaged from 2 or more cardiac cycles, even during normal sinus rhythm.**
True or false?
True
False
True
91
What cardiac diseases describe the importance's of right-heart size and function?
Myxomatous mitral valve disease, especially with concurrent pulmonary hypertension (dogs);
Hypertrophic cardiomyopathy (cats);
Precapillary pulmonary hypertension (dogs > cats);
Arrhythmogenic (RV) cardiomyopathy (dogs > cats);
Pulmonary stenosis (dogs).
92
What challenges are posed with imaging of the right ventricle?
1. **Complex anatomic shape**. Triangular in the long-axis and crescent-shaped in the short-axis imaging planes, the RV requires multiple imaging planes.
2. **Highly load-dependent**. RV size and function can change rapidly and significantly as a result of a sinus arrhythmia and changes in preload (venous return) due to changes in intrathoracic pressure associated with normal breathing.
93
True or false, the right atrium and left atrium are of the same size.
False. The RA is normally at least slightly smaller relative to the LA. The RA should not appear larger than the LA.
94
True or false, the right ventricular walls and the left ventricular walls are roughly the same size.
False. RV wall thickness is normally one-third to one-half the thickness of the LV.
95
True or false, the right ventricular chamber lumen should not appear larger than the LV
True. The minor dimensions of the RV are usually <50% of the LV.
96
True or false, during systole, the interventricular septum may appear flattened.
False. The interventricular septum should not appear flattened. Relative to the LV, it should appear rounded outward (convex) in both systole and diastole. This is easiest for most to appreciate from short-axis imaging.
RV pressure overloads cause flattening of the IVS primarily in systole
RV volume overloads causes flattening of the IVS primarily in diastole
97
How can we quantitate right atrial size?
The quantitative assessment of right atrial size is not well-studied in veterinary medicine. As with LA size measurements, perform RA size assessment at its maximum dimension i.e., at **end (ventricular)-systole**, just prior to tricuspid valve opening.
98
Describe various cardiac pathologies that may contribute to **right ventricular simple dilation**?
Acute volume (or pressure) overloads
Severe, end-stage right ventricular cardiomyopathy (cats > dogs)
99
Describe various cardiac pathologies that may contribute to **dilation with normal wall thickness (eccentric hypertrophy)**.
Tricuspid valve regurgitation secondary to tricuspid valve dysplasia
Atrial septal defects
Chronic bradyarrhythmia's (RV and LV hypertrophy)
100
Describe various cardiac pathologies that may contribute to right ventricular **wall thickening at the expense of ventricular lumen (concentric hypertrophy)**.
Congenital pressure overloads such as pulmonary stenosis, tetralogy of Fallot, reversed VSD, reversed PDA
Some cases of hypertrophic cardiomyopathy (LV and RV hypertrophy)
101
Describe various cardiac pathologies that may contribute to right ventricular **concentric hypertrophy with chamber dilatation? (mixed hypertrophy)**
Acquired pressure overloads i.e., precapillary pulmonary hypertension
102
How do we assess right ventricular chamber size?
Due to the complex shape of the RV, RV volume estimates (RV EDV, RV ESV) are rarely performed using 2D echocardiography.
RV areas and linear measurements serve as rough surrogates (at end-diastole)
103
**True or false, pericardial thickness is included in the RV free wall thickness measurement.**
False.
104
Describe the process of right ventricular shortening?
RV shortening (contraction) involves motion in both the minor (RV free wall moves toward the septum; transverse plane) and major axes (RV base or tricuspid annulus moves toward the apex; longitudinal plane). However, the majority of RV contraction (~75%) occurs along its major axis (in the longitudinal plane).
Because the majority of RV contraction occurs in the longitudinal plane (along its major axis), quantitative RV imaging focuses on the longitudinal plane and motion.
105
What is TAPSE and how do you measure it using M-mode?
Tricuspid Annular Plane Systolic Excursion (TAPSE).
Performed in the modified, left apical 4-chamber, optimized towards the right ventricle.
TAPSE involves measuring the distance (mm or cm) the lateral tricuspid annulus moves from end-diastole to end-systole (i.e., its maximum excursion) in the vertical plane (yellow arrow). It ideally consistently tracks the same region of the lateral tricuspid annulus throughout the cardiac cycle.
106
How do you perform TAPSE using 2DE?
At end-diastole (immediately after tricuspid valve closure) a line is drawn (white line, left) from the lateral tricuspid annulus to the region of the RV apex.
Next, with the line remaining on the screen, advance the video frame to end-systole (immediately before tricuspid valve opening) and draw a second line (yellow line, right) parallel to the first (white line) from the same exact point of the tricuspid annulus (now apically displaced) back to the starting point of the first line (white line, i.e., where the tricuspid annulus was at end-diastole).
107
True or false, TAPSE values are interchangeable between 2D and M-mode?
False. TAPSE measurements by M-mode and 2D echocardiography ARE NOT interchangeable.
2D TAPSE commonly yields **smaller values** relative to M-mode TAPSE. Separate reference intervals for each are available for use in dogs.
108
True or false, Because TAPSE is a linear measurement, it must be normalized to body size.
True.
TAPSE is typically normalized via allometric scaling.
109
Describe the image: Position, Measurement, and significance of decrease and increased values?
Right parasternal short-axis basilar view optimised for the right ventricular outflow tract.
MPA:Ao.
PA/Ao >1 is suggestive of clinically significant dilation of the pulmonary artery in dogs with pulmonary hypertension.
PA/Ao <0.8 is suggestive of clinically significant annular hypoplasia of the pulmonary artery in dogs with pulmonary stenosis.
110
**Which of the following is recommended for routine assessment of RV systolic function? **
A. RV fractional shortening
B. Tricuspid annular plane systolic excursion (TAPSE)
C. RV fractional area change
D. RV ejection fraction
Tricuspid annular plane systolic excursion (TAPSE)
111
**Which of the following contributes to the majority of RV contraction/systolic function?**
A. Contraction of the interventricular septum
B. Transverse (inward) movement of RV free wall (minor axis)
C. Longitudinal motion of the tricuspid annulus toward the apex (major axis)
D. RV twist/torsion
Longitudinal motion of the tricuspid annulus toward the apex (major axis).
112
**True or false, RV pressure overloads cause flattening of the interventricular septum primarily in diastole? **
True
False
False.
RV PRESSURE overloads causes flattening of the interventricular septum in SYSTOLE
RV VOLUME overloads causes flattening of the interventricular septum in DIASTOLE.
113
What is the effect of severe pericardial effusion on the right-side of the heart?
Compression of the cardiac chambers, especially the RA and RV are suggestive of significantly elevated intrapericardial pressure i.e., **cardiac tamponade**. Diastolic collapse of the RV and inversion of the RA wall are common.
The RA and RV walls usually appear thickened (“pseudohypertrophied”). Cardiac tamponade leads to impaired (right) ventricular filling and increased systemic venous pressure and, over time, the clinical syndrome of right-sided congestive heart failure with ascites
114
What clinical questions should be asked whether to perform a pericardiocentesis in dogs with the presence of cardiac tamponade?
The decision is likely best made based on the combination of:
1. Clinical signs (collapse, weakness, exercise intolerance);
2. Evidence of elevated systemic venous pressure (jugular venous distension, caudal vena cava dilation and reduced collapsibility);
3. Ascites.
115
Where are the most likely places to discover a cardiac mass?
1. Heart base
2. Right atrioventricular groove/junction (image);
3. Right auricle are common locations in dogs
116
Which of the following are characteristic focused echo features of pericardial effusion secondary to a LA tear? Select all that apply.
A. Small-volume pericardial effusion
B. Large volume pericardial effusion
C. Echogenic intrapericardial thrombus (usually large) originating from the LA free wall (site of the tear/rupture) and adjacent to the left heart
D. Some degree of relative left heart enlargement
E. Unequivocal RA enlargement
A. Small-volume pericardial effusion
C. Echogenic intrapericardial thrombus (usually large) originating from the LA free wall (site of the tear/rupture) and adjacent to the left heart
D. Some degree of relative left heart enlargement
117
What are some key features tied to pericardial effusion in cats?
Usually small-volume.
Usually results from increased venous pressure (not a cause of increased venous pressure as with dogs). In other words, congestive heart failure is the most common cause of pericardial effusion in cats.
Congestive heart failure is the most common cause of pericardial effusion in cats and pericardiocentesis is rarely necessary.
Concurrent atrial (right, left, or both) enlargement is highly suggestive that pericardial effusion is a manifestation of heart failure in cats.
118
Which condition presents with similar clinical signs to PH, and as a result is often misdiagnosed?
Dogs with PH can mimic dogs with severe MMVD with suspected heart failure – both commonly present with breathing difficulty or cough, collapse, systolic murmurs, and cardiomegaly on thoracic radiographs.
119
**Which of the following focused echo findings most likely corroborates that ascites is secondary to right-sided congestive heart failure in a dog?**
A. Severe left atrial enlargement
B. Severe right atrial enlargement
C. Pulmonary artery enlargement
D. Spontaneous echogenic contrast (“smoke”)
Severe right atrial enlargement
120
**Which of the following focused echo findings most likely corroborates that pleural effusion is secondary to congestive heart failure in a cat?**
A. Severe right atrial enlargement
B. Pulmonary artery enlargement
C. Severe left atrial enlargement
D. Spontaneous echogenic contrast (“smoke”)
Severe left atrial enlargement
121
**Which of the following focused echo findings most likely corroborates that precapillary pulmonary hypertension is the culprit for unexplained syncope in a dog? **
A. Pericardial effusion
B. Pleural effusion
C. Pulmonary artery enlargement
D. Spontaneous echogenic contrast (“smoke”)
Pulmonary artery enlargement
122
**Which of the following best describes echocardiography?**
A. Non-invasive examination of cardiac structure and function using x-rays
B. Non-invasive examination of cardiac electrical activity using sound waves
C. Non-invasive examination of cardiac structure and function using sound waves
D. Non-invasive examination of cardiac structure and function using magnetic fields
Non-invasive examination of cardiac structure and function using sound waves
123
**Which of the following IS NOT necessary to perform an ideal echocardiographic examination?**
A. Compliant and stable patient
B. Skilled and knowledgeable sonographer
C. At least one assistant to apply gentle manual restraint to the patient
D. General anaesthesia
General anaesthesia
124
**Which of the following represents the largest difference between cardiac and non-cardiac (e.g., abdominal) ultrasound imaging?**
A. Ultrasound unit
B. Primary imaging modality utilised
C. Transducer (probe) type
D. Display screen type
Transducer (probe) type
125
**Which of the following best describes the primary advantage of M-mode echocardiography relative to B-mode (two-dimensional) imaging?**
A. Less off-angle imaging
B. Multi-dimensional
C. High temporal resolution
D. Superior diastolic function assessment
High temporal resolution
126
Which of the following imaging modalities serves as the foundation of the echocardiographic examination?
A. M (motion)-mode imaging
B. Two-dimensional imaging
C. Three-dimensional imaging
D. Color Doppler imaging
Two-dimensional (2D) imaging
