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Heart

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Abstract

Transthoracic cardiac ultrasonography, or echo-cardiography, provides high-quality images of the heart, great vessels and paracardiac structures. It has developed into an essential diagnostic tool for the evaluation of dogs and cats with cardiac disease. This chapter looks at indications and the value of echocardiography compared with radiography. It moves on to address imaging technique and normal echocardiographic appearance. Congenital cardiac diseases, acquired valvular diseases, myocardial diseases, pericardial diseases and screening programmes for cardiac diseases are all covered. This chapter contains 30 video clips.

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Figures

Image of 6.2
6.2 A dog restrained in right lateral recumbency on a ‘cut out’ table, which allows echocardiographic examination from underneath.
Image of 6.4
6.4 2D echocardiogram recorded from the right parasternal long-axis window, revealing the left and right cardiac chambers. Ultrasound waves reflected by structures closer to the transducer are displayed at the top of the image, which is shown in greyscale. Note the ECG tracing at the bottom of the image, which is used to identify the phases of the cardiac cycle. M-mode echocardiogram recorded through the left ventricle at the level of the papillary muscles. Motion of the interventricular septum and left ventricular free wall is shown over many cardiac cycles. PW Doppler echocardiogram of blood flow, obtained by placing the sample volume within the left ventricular outflow tract. Note that the envelope of the Doppler tracing is empty, indicating laminar blood flow during systole. The Doppler tracing is displayed below the baseline, indicating that blood flow is away from the transducer. Colour flow Doppler echocardiogram recorded in a cat with a ventricular septal defect. Note the pyramid-shaped region of interest, in which colour Doppler is performed and superimposed on to the 2D image. Red indicates blood travelling towards the transducer; blue indicates blood travelling away from the transducer; and turbulent blood flow is displayed as a mosaic of colours. CW Doppler echocardiogram recorded from a subcostal window in a dog with subaortic stenosis. Note that the Doppler flow profile is filled, indicating that many different blood flow velocities have been recorded along the ultrasound beam at the same time. LA = left atrium; LV = left ventricle; P = pericardium–lung interface; RA = right atrium; RV = right ventricle.
Image of 6.5
6.5 2D right parasternal long-axis views. Transducer placement between the sternum and the costochondral junction at the level of the precordial impulse. The transducer is aligned with the long axis of the heart (from apex to base). In most dogs and cats, the long axis of the heart is along a line connecting the xiphoid process to the caudal border of the scapula at a 45-degree angle with the spine. On the monitor, the image should be oriented with the base of the heart to the right side of the screen, with the reference mark symbol on the top right side of the image and the reference index of the transducer pointing towards the heart base (i.e. oriented towards the patient’s head in most cases). The right parasternal long-axis 4-chamber view allows visualization of the right atrium (RA), right ventricle (RV), left atrium (LA) and left ventricle (LV). Note the pulmonary vein (PV) entering the left atrium. The aortic root (Ao) and aortic valve are visualized from the right parasternal long-axis outflow view. Starting with the 4-chamber plane, the outflow view is obtained by tilting the transducer more vertically with a slight clockwise rotation when the animal is in right lateral recumbency. LAu = Left auricular appendage.
Image of 6.6
6.6 2D right parasternal short-axis views. Transducer orientation with the ultrasound beam perpendicular to the long axis plane. The reference mark of the probe is oriented towards the animal’s elbow. The transducer is positioned so that the pulmonary artery is visualized on the right side of the screen when the base of the heart is imaged. By sweeping the ultrasound beam between the apex and the base of the heart, the operator can examine various cardiac structures (displayed as successive 2D planes). Left ventricular papillary muscle level. The right ventricle (RV; displayed at the top of the screen) has a crescent-shaped appearance and is positioned above the left ventricle (LV). The anterolateral (ventral) papillary muscle (PM) is visible on the right side of the screen; it may also be visualized on the right parasternal long-axis outflow view. The posteromedial (dorsal) papillary muscle is on the left side of the screen. Mitral valve level. In this view the mitral valve looks like a ‘fish mouth’ in diastole. Aorta level. The transducer is angled towards the base of the heart. In this view, the right atrium (RA), right ventricle and right ventricular outflow tract (RVOT) are visualized. The left atrium (LA) lies below the aorta (Ao). Pulmonary artery level. With further tilting of the transducer, a view of the pulmonic valve and pulmonary artery (PA) with its bifurcation is obtained. rPA = right pulmonary artery.
Image of 6.7
6.7 2D left caudal (apical) views. The transducer is placed in the left intercostal space where the precordial impulse is palpated; usually the 6th intercostal space. This is also the region of the apex of the left ventricle. With the animal in left lateral recumbency, the transducer is placed on the left sternal border, held at a 30–40 degree angle to the animal’s sagittal plane and oriented towards the left shoulder of the patient with the reference index facing the floor. With the transducer in this position, the heart is displayed upside down on the monitor, with the apex on top of the screen and the left cardiac chambers on the right side. 4-chamber view. This view shows all four cardiac chambers, the interatrial septum, the interventricular septum and the atrioventricular valves. LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle. 5-chamber view. This view allows visualization of the left ventricular outflow tract and the aorta (Ao).
Image of 6.8
6.8 2D left cranial views. The transducer is moved along the sternal border towards the left axillary region. The transducer is oriented towards the spine of the animal. This view shows the long axis of the ascending aorta (Ao), the left ventricle (LV) and the left atrium (LA). The index mark of the transducer is directed towards the head of the animal and the transducer is kept in contact with the left sternal border. This view allows visualization of the pulmonic valve and main pulmonary artery (PA). It requires the transducer to be held almost parallel to the animal’s sagittal plane. Portions of the aortic root and descending aorta (Ao) are also visible. RVOT = right ventricular outflow tract.
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6.9 Phased-array transducer. The index mark on the transducer indicates the plane of the ultrasound beam.
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6.11 M-mode echocardiogram of the left ventricle from a right parasternal short-axis view at the chordae tendinae level. The M-mode cursor is positioned perpendicular to the interventricular septum (IVS) and bisects the free (posterior) wall of the left ventricle between the papillary muscles. The left ventricular internal diameter at end-diastole (LVIDd) is measured at the onset of the QRS complex on the ECG. The left ventricular internal diameter at end-systole (LVIDs) is measured at the point of maximal posterior excursion of the interventricular septum. The shortening fraction (FS) is calculated from the LVIDd and LVIDs. The ejection fraction (EF) is automatically calculated using the Teichholz’s formula (Teich), which is based on the cube formula with correction factors for the increasingly spherical shape of the ventricle with increasing dilatation. The interventricular septum wall thickness in diastole and systole, and the left ventricular posterior wall (LVPW) thickness in diastole and systole have also been measured. Note that the echolucent line at the epicardium–lung interface is consistent with a small amount of pericardial effusion (PE).
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6.12 Right parasternal long-axis 4-chamber view showing measurement of the left ventricular internal diameter (LVID). The diameter is measured between the papillary muscles and the mitral valve, perpendicular to the long axis of the heart.
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6.13 PW Doppler echocardiogram of the normal mitral valve inflow velocities. From the left apical 4-chamber view, the ultrasound beam is aligned parallel to the blood flow across the mitral valve. The sample volume is placed at the level of the tips of the mitral valve leaflets. Mitral valve inflow is recorded as a biphasic flow. The early rapid filling wave (E) is larger than the second wave resulting from atrial contraction (A).
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6.15 Length and diameters of the right ventricle inflow portion measured on an apical 4-chamber view. D1 represents the diameter of the right ventricle at the tricuspid valve annulus. D2 is the diameter of the right ventricle at the level of the left ventricular papillary muscles. L is the length of the right ventricular inflow portion from the tricuspid annulus to the apex.
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6.16 Left atrial (LA) and aortic (Ao) diameters obtained from a right parasternal short-axis view at the level of the aortic valve. The measurement is made on the first frame following aortic valve closure. The aortic diameter is measured along the commissure between the left coronary and right coronary aortic valve cusps. The left atrial diameter is measured on the same frame on a line extending from and parallel to the commissure, between the non-coronary and left coronary aortic valve cusps to the blood–tissue interface of the left atrial wall. Left atrial circumference and area can also be determined by tracing the contour of the atrium on a 2D frame. LC = left coronary cusp; RC = right coronary cusp.
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6.17 Modified left apical 4-chamber view obtained by tilting the transducer medially. The coronary sinus (arrowed) is seen as an echo-free linear structure opening in the right atrium (RA) at the level of the atrioventricular junction. A dilated coronary sinus is usually seen with cardiac conditions associated with elevated right atrial pressures. RV = right ventricle.
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6.19 Mitral valve anatomy. Right parasternal long-axis 4-chamber view recorded in early systole in a dog with normal mitral valve apparatus. The mitral valve apparatus comprises the parietal (posterior, caudal) and septal (anterior, cranial) leaflets, the annulus, the underlying left ventricular wall and the chordae tendinae (CT). Chordae tendinae are attached to the tip and mid portion of the leaftets and anchor them to the papillary muscles. The septal leaflet of the mitral valve (MV) is continuous with the aortic valve (AoV) and together with the interventricular septum define the anatomical region of the left ventricular outflow tract. M-mode recording of the mitral valve. The interrogation beam transects the tip of the leaflets. The septal leaflet motion follows a typical ‘M’ shape pattern in diastole. This corresponds to the valve opening during early diastole (E point), slowly returning to a closed position and re-opening during atrial contraction (A point). LA = left atrium; LV = left ventricle; PM = papillary muscles.
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6.20 Tricuspid valve anatomy. Right parasternal long-axis view. The tricuspid valve apparatus consists of the parietal (P L) and septal (S L) leaflets, the tricuspid valve annulus, which is slightly more apical than the mitral valve annulus, and the chordae tendinae, which are much thinner in the right ventricle than in the left ventricle. Note that the tricuspid valve is made of only two leaflets in dogs and cats. RA = right atrium.
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6.21 Aortic valve and aorta anatomy. The three cusps are visualized from the right parasternal short-axis view at the level of the aortic valve. In this plane, the three lines of closure form a Y shape in diastole. Starting from the left coronary cusp (L), which faces the left auricular appendage, and rotating clockwise, there are the non-coronary cusp (S) and the right coronary cusp (R). The right cusp faces the right ventricular outflow tract (RVOT). The cusps are crescent-shaped. They open fully in systole and their commissures form a tight seal in diastole preventing backflow from the aorta into the left ventricle. Three aortic sinuses or sinuses of Valsalva (SV) appear as dilatation of the aorta, just above the aortic valve. The left and right coronary arteries originate from the left and right sinuses, respectively. The ascending aorta is also visualized from this right parasternal long-axis outflow view. LA = left atrium; RA = right atrium.
Image of 6.22
6.22 Pulmonic valve and pulmonary artery anatomy. The pulmonary trunk originates from the right ventricular outflow tract (RVOT). It wraps around the ascending aorta (Ao) with its medial surface in contact with the aortic wall. This is visualized best on a right parasternal short-axis view at the aortic valve level. The pulmonary trunk bifurcates into the right pulmonary artery (PA), which leaves the main pulmonary artery at nearly a right angle, and the left pulmonary artery (PA), which is shorter and more difficult to image on a transthoracic echocardiogram. The pulmonic valve is similar in structure to the aortic valve. The cusps of the valve are thinner than the aortic cusps, and are more difficult to image.
Image of 6.23
6.23 Colour flow Doppler image of a PDA from a left cranial view. Turbulent flow (displayed as a mosaic of colours) delineates the walls of the ductus. The colour jet narrows at the junction between the PDA and the main pulmonary artery. Laminar blood flow within the pulmonary artery is shown in blue.
Image of 6.24
6.24 A PDA is clearly seen (*) opening into the pulmonary artery (PA) on this left parasternal cranial view. Note that part of the PDA seems to travel within the wall of the descending aorta (Ao).
Image of 6.25
6.25 This view of a PDA (*) was obtained by transoesophageal echocardiography with the transducer placed in a cranial position and oriented at 54 degrees. The minimal ductal diameter, which corresponds to the junction between the PDA and the pulmonary artery (PA), was measured prior to transcatheter occlusion of the PDA with a canine ductal occluder. Transoesophageal echocardiography can be used to assess placement of the occlusion device and the presence of residual blood flow (on colour Doppler imaging) prior to its release.
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6.26 Right parasternal long-axis 4-chamber view showing left ventricular (LV) and left atrial (LA) enlargement in a dog with a PDA. Note that left ventricular enlargement occurs sooner and is more pronounced than left atrial dilatation. However, with time, left atrial pressures increase, causing signs of left-sided congestive heart failure. M-mode image of the left ventricle of a 4-year-old, 15 kg dog with a PDA. There is severe left ventricular enlargement and a decreased shortening fraction. Note the irregular ECG rhythm caused by frequent ventricular premature beats. At this stage of the disease, it is still recommended to occlude or ligate the PDA. However, long-term prognosis is guarded.
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6.27 Use of Doppler echocardiography to measure pressure gradients.
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6.28 CW Doppler is used to measure the velocity of flow through a PDA from a left parasternal cranial view. The flow is continuous. The maximal flow velocity can be used to estimate the pressure gradient between the aorta and the pulmonary artery. In this case, a peak velocity of 4 m/s corresponds to a pressure gradient of 64 mmHg (using the simplified Bernoulli equation, see text for details), suggesting elevated pulmonary artery pressure. The normal pressure gradient is expected to be around 85 mmHg (peak systolic pressure in the aorta of 120 mmHg; peak systolic pressure in the pulmonary artery of 25 mmHg).
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6.29 Right parasternal short-axis view of a dog with severe pulmonary hypertension. The right ventricle (RV) is severely dilated and there is flattening of the interventricular septum (*) throughout the cardiac cycle. Severe dilatation of the main pulmonary artery (PA) and right pulmonary artery (RPA) as visualized from a right parasternal view. A severely dilated right pulmonary artery (RPA) is visualized in cross-section from the right parasternal long-axis outflow view. Note that the right atrium (RA) is markedly dilated. CW Doppler recording of a tricuspid valve regurgitant jet. The pressure gradient between the right ventricle and the aorta is estimated from the peak velocity of the tricuspid jet, measured at 53 mmHg. This indicates that pulmonary artery pressure is at least 53 mmHg. This is consistent with moderate pulmonary hypertension. AO = aorta; LV = left ventricle; RA = right atrium.
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6.31 Different types of ASD. LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
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6.32 Echocardiogram showing an ASD (*) in a dog with left atrial (LA) enlargement secondary to chronic degenerative mitral valve disease. The location of the defect is consistent with an ostium secundum defect. It is possible that marked stretching of the atrial septum may restore patency at the level of the foramen ovale, if the membrane of the foramen has not fused with the atrial septum soon after birth. LV = left ventricle; RA = right atrium.
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6.33 Left-to-right flow, demonstrated by Doppler imaging from a modified left apical view, in a dog with an ostium secundum ASD and a markedly enlarged left atrium secondary to mitral valve regurgitation. Note that left-to-right shunting increases following the P wave on ECG (i.e. atrial contraction). Shunting is also increased during ventricular systole. This is most likely due to elevated left atrial pressures caused by mitral valve regurgitation.
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6.34 Restrictive perimembranous VSD in a cat. The VSD (arrowed) is visualized just below the aortic valve (Ao) on a right parasternal long-axis outflow view. The left atrium (LA) appears to be mildly dilated. The clinical significance of a VSD is determined by calculating the left atrial (LA) to aortic (Ao) diameter ratio from a right parasternal short-axis view. A LA/Ao ratio of 1.6 indicates mild atrial enlargement. Linear measurements of the interventricular septum, left ventricular internal diameter in diastole (LVIDd) and left ventricular free wall can be obtained using this image. The LVIDd is 2.1 cm, which is consistent with moderate left ventricular (LV) dilatation (normal LVIDd in cats is approximately 1.3 cm). Blood flow velocity (Vel) is measured across the defect using CW Doppler. The pressure gradient between the ventricles is determined using the simplified Bernoulli equation. In this case the pressure gradient was 95.3 mmHg. Colour Doppler imaging confirms the presence of a VSD. The dimensions of the colour flow jet across the defect may provide an estimate of the size of the VSD. The position of the VSD at 10 o’clock and the blood flow turbulence across the defect, as shown by Doppler imaging from a right parasternal short-axis view at the level of the left ventricular outflow tract, confirm that the VSD is perimembranous and restrictive. RV = right ventricle.
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6.35 Colour Doppler image demonstrating turbulent systolic flow in the left ventricular outflow tract of a dog with subaortic stenosis. A mild degree of aortic valve regurgitation was visualized in diastole. LA = left atrium, LV = left ventricle.
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6.36 Right parasternal long-axis outflow view showing a ridge of fibrous tissue (*) just below the aortic valve (Ao). LA = left atrium; LV = left ventricle.
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6.37 The ascending aorta (Ao) visualized from a subcostal window. Blood flow is perfectly aligned with the ultrasound beam. CW Doppler image demonstrating a peak velocity of 4 m/s, consistent with a peak pressure gradient of 64 mmHg across the stenosis.
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6.38 M-mode echocardiogram of a dog with severe subaortic stenosis demonstrating concentric hypertrophy of the interventricular septum and left ventricular free wall.
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6.39 Subvalvular and valvular stenosis in a dog. A fibromuscular area of stenosis (*) is visible in the right ventricular outflow tract region from a right parasternal short-axis view. Valvular stenosis (arrowed) is also present. There is marked post-stenotic dilatation of the main pulmonary artery (PA). The colour Doppler image shows the turbulent blood flow originating at the level of the subaortic region. RV = right ventricle.
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6.40 Coronary artery anomaly (type R2A) in an English Bulldog with pulmonic stenosis. The right parasternal short-axis view at the level of the aorta (Ao) reveals a large coronary artery, originating at the level of the right coronary cusp (RC) and travelling in from the right ventricular outflow tract (RVOT), just below the valve. This may be an echocardiographic sign of a coronary anomaly. However, it is common for dogs with severe pulmonic stenosis to have a dilated right coronary artery. An angiogram is usually necessary to confirm the suspicion. Note the post-stenotic dilatation of the main pulmonary artery (PA). Aortic root angiogram showing the main left coronary artery (*) branching from the origin of the right coronary artery. No artery is seen originating from the left sinus of Valsalva. BrT = brachiocephalic trunk; LC = left coronary cusp; ScA = subclavian artery.
Image of 6.41
6.41 Right parasternal short-axis view in a dog with valvular pulmonic stenosis. There is mild thickening of the valvular cusps. A post-stenotic bulge of the main pulmonary artery (PA) is present. The dog was diagnosed with severe pulmonic stenosis. However, the right ventricular (RV) hypertrophy is only moderate. The right atrium (RA) is mildly dilated. Ao = aorta; rPA = right pulmonary artery.
Image of 6.42
6.42 CW Doppler image through the right ventricular outflow tract and the pulmonic valve of a dog with pulmonic stenosis. The peak pressure gradient in systole is approximately 64 mmHg (peak velocity of 4 m/s). Note that pulmonic valve insufficiency is also present.
Image of 6.43
6.43 Right parasternal long-axis 4-chamber view, revealing severe dilatation of the right atrium (RA) and right ventricle (RV) in a dog with tricuspid valve dysplasia. The anterior leaflet of the valve is elongated. Note the hypertrophied moderator band (*). LV = left ventricle.
Image of 6.44
6.44 Colour Doppler image from the left apical 4-chamber view in a dog with tricuspid valve dysplasia. A large jet of tricuspid valve regurgitation covers approximately 50% of the area of the right atrium. LA = left atrium; LV = left ventricle; RV = right ventricle.
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6.45 2D echocardiogram of the mitral valve in a dog with mitral valve dysplasia. The elongated septal leaflet (arrowed) is connected to the papillary muscle by short and thick chordae tendinae. Ao = aorta; LA = left atrium.
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6.46 Early systolic right parasternal long-axis 4-chamber view showing the prolapse of the septal leaflet (*) of the mitral valve behind the plane of the annulus. LA = left atrium; LV = left ventricle.
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6.47 Right parasternal long-axis 4-chamber view in a dog with chronic degenerative valve disease. The left atrium is markedly enlarged and the interatrial septum is bowing towards the right atrium. Myxomatous lesions (*) are visualized on the mitral valve leaflets. Right parasternal long-axis 4-chamber view in a dog with a flail septal leaflet (*). Note that the leaflet and attached chordae are positioned above the mitral valve annulus, and that the tip of the leaflet is pointing away from the left ventricular apex. LA = left atrium; LV = left ventricle.
Image of 6.48
6.48 The left atrial diameter to aortic diameter ratio (LA/Ao) is determined from the right parasternal short-axis view at the level of the aortic valve. In this case the ratio is 2.8, which indicates severe atrial enlargement secondary to chronic mitral valve disease. Normal LA/Ao ratio is approximately 1.4.
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6.49 M-mode image of the left ventricle (LV) in a dog with chronic mitral valve disease. The left ventricular contraction is hyperdynamic, as demonstrated by the shortening fraction (FS) at 52%. This is a result of the low resistance to blood ejection during systole created by the large volume of regurgitation into the low pressure left atrium. Note that the motion of the interventricular septum (IVS) is more pronounced than the motion of the left ventricular free wall (LVPW). This is common in dogs with chronic mitral valve disease.
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6.50 Right parasternal long-axis view in a dog with moderate to severe mitral valve regurgitation. The colour flow covers approximately 50% of the total left atrial surface. This is consistent with moderate mitral valve regurgitation. Note that the size of the left atrium is another parameter used to define the severity of the disease, and this may be a stronger predictor of the risk of developing congestive heart failure than the size of the mitral valve regurgitation jet.
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6.51 CW Doppler image of a jet of mitral valve regurgitation. The peak velocity of the jet is approximately 5 m/s and corresponds to a pressure gradient of 100 mmHg between the left ventricle and the left atrium.
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6.52 A large aortic valve vegetation (*) is seen in diastole from the right parasternal long-axis outflow tract view. Ao = aorta; LA = left atrium; LV = left ventricle.
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6.53 Canine DCM. Right parasternal long-axis 4-chamber view in diastole. Note the dilatation and spherical shape of the left ventricle (LV). Systolic frame demonstrating the generalized hypokinesis of the myocardium. M-mode echocardiogram demonstrating that the shortening fraction (FS) is approximately 10.7%. M-mode echocardiogram recorded at the level of the mitral valve. The increased E-point to septal separation (EPSS) is an indication of decreased ejection fraction. LA = left atrium; LVIDd = left ventricular internal diameter in diastole; LVIDs = left ventricular internal diameter in systole.
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6.54 M-mode echocardiogram in a cat with HCM. The left ventricular free wall is markedly thickened. Note that the hypertrophy of the interventricular septum is less pronounced. An echo-free space, consistent with pericardial effusion (PE) is seen below the left ventricular free wall. LV = left ventricle.
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6.55 Right parasternal short-axis view at the papillary muscle level in a cat with HCM. This view allows the distribution of hypertrophy between the interventricular septum and the wall of the left ventricle (LV) to be appreciated. Note the two prominent papillary muscles. This is a finding consistent with HCM.
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6.56 Right parasternal long-axis 4-chamber view recorded in early systole in a cat with HCM (same cat as in Figure 6.52 ). The left atrium (LA) is markedly enlarged. There is massive hypertrophy of the left ventricular free wall. Note the hypertrophy at the base of the septum in the region of the left ventricular outflow tract. A small amount of pericardial effusion (*) is present. LV = left ventricle.
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6.57 M-mode echocardiogram of a cat with HCM showing SAM of the mitral valve (*). During systole there is anterior displacement of the mitral valve, which results in contact with the interventricular septum, and provides evidence of left ventricular outflow tract obstruction.
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6.58 Right parasternal long-axis 4-chamber view with colour flow Doppler of the left ventricular outflow tract and mitral valve areas. On this systolic image, turbulent blood flow (arrowed) is identified in the outflow tract secondary to SAM of the mitral valve. There is secondary mitral valve regurgitation resulting from the abnormal coaptation of the leaflets. Note the small eccentric jet of mitral valve regurgitation. Ao = aorta; LA = left atrium; LV = left ventricle.
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6.59 CW Doppler image of the flow in the left ventricular outflow tract in a cat with obstructive HCM. Note the late peaking ‘dagger’ shaped contour of the spectral display. This CW Doppler profile reflects the occurrence of the obstruction during mid- to late systole.
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6.60 PW Doppler image of mitral valve inflow in a cat with HCM. The sample window is placed at the level of the tip of the mitral valve leaflets in diastole. There is an E/A wave ratio reversal, indicating an abnormal relaxation pattern of the left ventricle.
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6.61 Left atrial (LA) to aortic (Ao) diameter ratio of 2.3 measured from a right parasternal short-axis view at the aortic valve level in a cat with HCM. Note the enlargement of the left auricular appendage.
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6.62 Right parasternal short-axis view in a cat with HCM showing a thrombus (*) in the left auricular appendage. Ao = aorta; LA = left atrium; RA = right atrium.
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6.63 Right parasternal short-axis view at the level of the papillary muscles in a dog with a severely enlarged left atrium (*). The left atrium is visualized on the lateral wall of the left ventricle (LV), mimicking pericardial effusion.
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6.64 Right parasternal long-axis 4-chamber view in a dog with cardiac tamponade. There is a large amount of pericardial effusion (PE) and a small mass is visible at the right atrioventricular junction (*). Note the collapse of the wall of the right atrium (RA) in diastole. This is a sensitive sign for cardiac tamponade.
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6.65 Right parasternal long-axis view in a dog with cardiac tamponade. Pericardial effusion is visible (PE). There is also a mass above the left atrium (*); this is usually consistent with a chemodectoma.
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6.66 A large heart base mass (*), compressing the dorsal wall of the left atrium, is visible on the left apical 4-chamber view. LV = left ventricle; RV = right ventricle.

Supplements

Left cranial view of the right atrium.

The right ventricle is seen closest to the transducer in this clip, with the right atrium deep to it. Movement of the right atrioventricular valve leaflets is clearly seen. Both the caudal and the cranial venae cavae can be seen entering the right atrium.

Patent ductus arteriosus viewed from the left cranial window.

This clip, using colour flow Doppler, demonstrates turbulent blood flow (with a mosaic of colours) shunting from the aorta into the pulmonary artery through the PDA.

Patent ductus arteriosus viewed from a transoesophageal approach.

The probe is placed over the oesophagus, cranial to the heart base, allowing a detailed view of the PDA (at the top of the screen). Colour flow Doppler is used to demonstrate the turbulent blood flow shunting from the PDA into the main pulmonary artery.

Patent ductus arteriosus.

This clip shows a right parasternal long-axis four-chamber view in a dog with a PDA. Although the PDA itself is not visible, there is left ventricular dilatation. Contractility remains within normal limits.

Bubble study.

Right parasternal long-axis four-chamber view in a dog during injection of agitated saline. Microbubbles are visible in the right cardiac chambers. In this normal dog, no contrast medium is seen within the left cardiac chambers.

Atrial septal defect.

The right atrium and ventricle are at the top of the screen, with the left atrium and ventricle below. The left atrium is markedly dilated secondary to mitral valve regurgitation. Left-to-right flow of blood across an ostium secundum ASD is demonstrated by colour flow Doppler.

Ventricular septal defect (1).

This clip shows a right parasternal short-axis view of the heart of a cat. The aorta is the round structure in the centre of the heart, with the right ventricle wrapped around it at the top of the screen. A small VSD (10 o’clock position) at the level of the left ventricular outflow tract is present. Turbulent blood flow can be seen to cross the defect into the right ventricle. The position of the defect and the turbulence of the flow indicate that the defect is perimembranous and restrictive.

Ventricular septal defect (2).

A right parasternal long-axis outflow view of the same cat as in Ventricular septal defect (1). A turbulent jet of blood is seen crossing from the left ventricle into the right ventricle just below the aortic valve.

Subaortic stenosis (1).

These clips show a right parasternal short-axis view of the heart in a dog. The right-hand clip shows a mosaic of colours within the central aorta, indicating turbulent blood flow. This turbulence was secondary to an SAS.

Subaortic stenosis (2).

This apical view shows the left ventricle in the center of the image close to the transducer, with the left atrium deep to it. Colour Flow Doppler shows turbulent flow in the left ventricular outflow tract during systole due to subaortic stenosis. There is mild aortic insufficiency during diastole.

Subaortic stenosis (3).

A right parasternal long-axis four-chamber view of the heart in a dog with SAS, showing concentric hypertrophy of the left ventricle. This dog also had moderate pulmonic stenosis, causing right ventricular wall hypertrophy.

Subaortic stenosis (4).

A right parasternal short-axis view of the left ventricle in a dog with SAS, showing diffuse concentric hypertrophy. Note the hyperechoic areas on the papillary muscles, which may indicate ischaemic lesions.

Pulmonic stenosis (1).

These clips show a right parasternal short-axis view of the heart at the level of the pulmonary artery. The dog was diagnosed with valvular pulmonic stenosis and subvalvular stenosis. On the 2D clip, the valve is clearly visible (towards the right of the screen), as is the hyperechoic membrane above the valve. Note the post-stenotic dilatation that accompanies the valvular stenosis. When colour Doppler is added to the 2D image, turbulent blood flow is seen originating from the hyperechoic membrane, which is consistent with subvalvular stenosis.

Pulmonic stenosis (2).

A right parasternal short-axis view, centred on the pulmonic valve. Note the motion of this doming valve. There is post-stenotic dilatation of the pulmonary artery.

Tricuspid valve dysplasia (1).

This clip shows a right parasternal short-axis view at the level of the ventricle in a dog with tricuspid valve dysplasia. The right ventricle is severely dilated. Flattening of a portion of the septum is visualized in diastole.

Tricuspid valve dysplasia (2).

A right parasternal long-axis four-chamber view of the heart of the same dog as in Tricuspid valve dysplasia (1), showing marked dilatation of the right atrium, which lies superficially and to the right of the screen. A puff of turbulent blood seen entering the right atrium across the tricuspid valve leaflets indicates tricuspid valve regurgitation.

Tricuspid valve prolapse.

This clip shows prolapse of the septal leaflet of the tricuspid valve into the right atrium.

Tricuspid valve regurgitation.

The left ventricle lies to the left of the screen, with the left atrium deep to it. The left atrium is dilated secondary to severe mitral valve endocardiosis. The right cardiac chambers lie to the right of the screen, and moderate tricuspid valve regurgitation is demonstrated with colour flow Doppler.

Mitral valve regurgitation (1).

Right parasternal long-axis four-chamber view in a dog with severe mitral valve endocardiosis. The left atrium and left ventricle are severely dilated. The mitral valve leaflets are thickened and the septal leaflet is seen to prolapse into the left atrium.

Mitral valve regurgitation (2).

Colour flow Doppler examination in the same dog as in Mitral valve regurgitation (1), demonstrating moderate mitral valve regurgitation and an eccentric jet.

Mitral valve regurgitation (3).

In this clip, a severe jet of mitral valve regurgitation is seen due to mitral valve insufficiency associated with endocardiosis.

Endocarditis (1).

This clip shows a right parasternal short-axis view at the level of the aortic valve in a dog with endocarditis. Irregular, hyperechoic, vegetative lesions are present on all three aortic cusps.

Endocarditis (2).

A right parasternal long-axis outflow view in the same dog as in Endocarditis (1). Note the large hyperechoic vegetations on the ventricular side of the aortic cusps.

Hypertrophic cardiomyopathy (1).

This clip shows a right parasternal short-axis view at the level of the papillary muscles in a cat. Systolic cavity obliteration due to severe hypertrophy of the left ventricle can be seen.

Hypertrophic cardiomyopathy (2).

A right parasternal long-axis four-chamber view of the heart in a cat with HCM, showing marked enlargement of the left atrium. The left ventricular free wall is diffusely thickened, and there is thickening of the base of the interventricular septum. Note the presence of a small pericardial effusion.

Systolic anterior motion of the chordae.

This clip, recorded from a right parasternal approach, demonstrates SAM of a chordae tendinae attached to the septal leaflet of the mitral valve.

Systolic anterior motion of the mitral valve.

These clips were recorded from a right parasternal window in a cat with SAM of the mitral valve. Turbulent blood flow is present in the left ventricular outflow tract during systole, accompanied by mild mitral valve regurgitation.

Pericardial effusion.

This clip shows a right parasternal short-axis view at the level of the papillary muscles. The heart is seen moving within a large amount of pericardial fluid.

Right atrial mass.

A left apical four-chamber view in a dog, showing a large hypoechoic right atrial mass. The mass expands into the right ventricular chamber and around the tricuspid valve.

Heart base mass.

This clip shows a large heart base mass in a dog, which expands into both the right and left atria.

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