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Congenital heart disease

image of Congenital heart disease
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Abstract

The vast majority of animals with congenital heart disease present with an audible murmur; thus, auscultation is the initial key diagnostic test. Nearly all congenital defects have a systolic murmur - except most notably a patent ductus arteriosus (PDA), which has a characteristic continuous murmur. However, some rare defects may have no murmur, such as a reversed/balanced shunt. Recent reviews of congenital heart disease are available. In very young puppies and kittens, flow murmurs are common. They are difficult to differentiate from a congenital defect on auscultation alone and thus create a diagnostic dilemma for the clinician when a murmur is discovered, and cause problems on how best to advise the owner. Murmurs in puppies and kittens; Patent ductus arteriosus; Aortic stenosis; Pulmonic stenosis; Ventricular septal defect; Mitral dysplasia; Atrial septal defect; Tricuspid dysplasia; Tetralogy of Fallot; Atrioventricular septal defect; Cor triatriatum dexter; Cor triatriatum sinister (CTS) and supravalvular mitral stenosis (SMS); and Other congenital defects are discussed.

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Figures

Image of 26.2
26.2 PDA. The ductus remains as a vascular connection between the descending aorta (Ao) and the main pulmonary artery (PA). There is a continuous left-to-right shunt of blood throughout systole and diastole, giving the characteristic waxing and waning continuous murmur, as aortic pressures exceed pulmonary artery pressures throughout the cardiac cycle. Post-mortem appearance of the heart of a dog with PDA, showing the aorta opened along its length. The forceps point to the duct. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission LA = Left atrium; LV = Left ventricle; RA = Right atrium; RV = Right ventricle.
Image of 26.4
26.4 Radiographs of a mature German Shepherd Dog with PDA and clinical signs of left-sided CHF. Lateral view showing marked LA and LV enlargement. The lung fields appear hypervascular. Cranial lobar pulmonary arteries and veins are both enlarged, and pulmonary venous distension is most marked. There is a generalized mixed (interstitial and alveolar) pulmonary infiltrate, consistent with pulmonary oedema, which is predominantly perihilar, although the alveolar infiltrate is well illustrated by the presence of air bronchograms in the cranial lobes. The DV view confirms the LA and LV enlargement and the pulmonary changes. Additionally, the classic ‘triple knuckle’ is seen between 12 and 3 o’clock, with a bulge on the descending aorta (12–1 o’clock), a pulmonary artery bulge (1–2 o’clock) and a left auricular appendage bulge (2–3 o’clock).
Image of 26.5
26.5 Right parasternal long-axis view of a dog with a PDA, demonstrating mild LA and LV dilatation. Left cranial parasternal view of a dog showing the duct between the aorta and pulmonary artery. Colour flow mapping of (b) showing laminar (red) flow within the ampulla of the duct and the turbulent jet of flow towards the transducer, arising from the ostium of the duct within the pulmonary trunk. Spectral Doppler recording of flow arising from the pulmonary ostium within the pulmonary trunk. The flow is continuous: waxes in systole (QRS complex to T wave) and wanes in diastole (T wave to QRS complex). Ao = Aorta; LA = Left atrium; LV = Left ventricle; PA = Pulmonary artery; RV = Right ventricle.
Image of 26.6
26.6 PDA closure with an ACDO. Angiogram taken following positioning of the ACDO, showing contrast medium in the aorta and duct, but none in the pulmonary artery, indicating absence of ductal flow. Radiograph showing the ACDO after release. Note the pre-existing cardiomegaly and pulmonary vascular pattern.
Image of 26.7
26.7 AS is usually in the form of a fibrous ring or crescent in the LVOT below the aortic valve (subaortic stenosis). This causes increased impedance to LV ejection (increased afterload). Compensatory concentric LV hypertrophy occurs to minimize LV wall stress. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission
Image of 26.9
26.9 Echocardiography of AS. LVOT and aortic valve. There is a visible subaortic lesion (arrowed). Colour flow mapping shows laminar (blue) flow proximal to the subaortic lesion and a turbulent jet of flow arising from the stenosis and continuing into the ascending aorta. Ao = Aorta; LA = Left atrium; LV = Left ventricle.
Image of 26.10
26.10 Spectral Doppler recording of a dog with subaortic stenosis. The peak velocity approaches 6 m/s, which equates to a trans-stenotic pressure gradient of 140 mmHg, classifying this as a severe stenosis.
Image of 26.11
26.11 PS. There is increased afterload on the RV due to the stenotic pulmonic valve. Secondary RV hypertrophy occurs, which may cause further dynamic RVOT (infundibular) obstruction, exacerbating the pressure gradient across this area. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission
Image of 26.13
26.13 RV angiogram showing RV hypertrophy, valvular PS (arrowed) and a post-stenotic dilatation (yellow arrow). The RVOT is also shown (arrowed). Note the absence of tricuspid regurgitation in this case.
Image of 26.14
26.14 Echocardiography of PS. Right parasternal long-axis view of a dog with a PS, demonstrating RV hypertrophy. The RA is also dilated, which was associated with a concurrent tricuspid dysplasia in this case. Right parasternal short-axis view of the LV and RV. Note the marked RV hypertrophy and mild flattening of the ventricular septum associated with the higher RV pressure. Right parasternal short-axis view with colour flow mapping recorded during systole, showing laminar (blue) flow approaching the stenosis and turbulent (mixed mosaic colours) flow distal to the stenosis. LA = Left atrium; LV = Left ventricle; PV = Pulmonic valve; RA = Right atrium; RV = Right ventricle.
Image of 26.15
26.15 Spectral Doppler recording of a dog with PS. The peak velocity approaches 8 m/s, which equates to a trans-stenotic pressure gradient of 250 mmHg, classifying this as a very severe stenosis. Within the spectral trace a second signal can be seen, with slower acceleration and lower peak velocity (arrowed). This appearance is typical of concurrent dynamic (infundibular) obstruction.
Image of 26.16
26.16 Fluoroscopic images showing balloon dilation of a PS. The indent in the balloon is associated with the stenosis. The balloon has been fully inflated to alleviate the stenosis.
Image of 26.17
26.17 Left cranial parasternal view (left) with colour flow mapping (right) of a young Labrador Retriever with a double-chambered RV. The arrow points to the obstruction which divides the RV. The image on the right shows the turbulent systolic flow through the defect. Ao = Aorta; PA = Pulmonary artery; RA = Right atrium; RV = Right ventricle.
Image of 26.18
26.18 VSD. There is a systolic pressure gradient between the LV and RV, allowing left-to-right shunting across the defect. The RV and pulmonary vasculature, LA and LV are therefore volume overloaded. Right parasternal long-axis view of a dog with a VSD, showing moderate LA and LV dilatation. Note that the VSD is not evident in this plane. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission LA = Left atrium; LV = Left ventricle; RA = Right atrium; RV = Right ventricle.
Image of 26.20
26.20 Echocardiography of feline VSDs. Right parasternal long-axis view showing a reasonably large VSD. Note: small VSDs can be difficult to see on 2D echocardiography. Colour flow mapping recorded in systole. Note the left-to-right flow through the VSD from just ventral to the aortic valve. Spectral Doppler recording through the VSD, showing flow towards the transducer in systole (QRS complex to T wave). The flow away from the transducer in diastole (T wave to QRS complex) is due to aortic regurgitation, which is common with a VSD, due to prolapse of the right coronary cusp of the aortic valve into the VSD. Ao = Aorta; LA = Left atrium; LV = Left ventricle; RA = Right atrium; RV = Right ventricle.
Image of 26.21
26.21 Mitral dysplasia. The dysplastic changes affecting the mitral valve may also affect the papillary muscles and the chordae tendineae and typically result in mitral incompetence. Mitral regurgitation causes LA and LV volume overload. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission
Image of 26.23
26.23 Mitral dysplasia results in volume loading of the left heart and therefore the LA and LV are seen to be dilated on echocardiography. Right parasternal long-axis view of a dog with mitral dysplasia, demonstrating mild LA and LV dilatation. It can be difficult to appreciate specific abnormalities of the mitral apparatus. Colour flow mapping recorded in systole, showing a large volume mitral regurgitation back into the LA. LA = Left atrium; LV = Left ventricle; RA = Right atrium; RV = Right ventricle.
Image of 26.24
26.24 Right parasternal long-axis view showing massive LA dilatation and a dysplastic, stenotic mitral valve in a Border Terrier with mitral dysplasia. This end-diastolic image shows the extent of opening of the mitral valve. The dog had atrial flutter as a consequence of severe atrial stretch. There is spontaneous echocontrast (‘smoke’) within the LA due to stasis of atrial flow. Colour flow mapping (diastolic image) shows high-velocity turbulent flow into the LV, corresponding to the diastolic murmur detected. Left apical four-chamber view with spectral Doppler recording showing mitral inflow. This view confirms the high-velocity, slowly decelerating mitral inflow typical of mitral stenosis. M-mode echocardiogram of the mitral valve. The anterior leaflet has an abnormal ‘box-shaped’ motion towards the septum; and the posterior leaflet motion parallels this, rather than moving towards the posterior wall. LA = Left atrium; LV = Left ventricle; RA = Right atrium; RV = Right ventricle.
Image of 26.25
26.25 Tricuspid dysplasia. The abnormal tricuspid valves are incompetent and tricuspid regurgitation results in volume overload of the RA and RV. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission
Image of 26.27
26.27 Tricuspid dysplasia results in volume loading of the right heart and therefore the RA and RV are seen to be dilated on echocardiography; the RA is often much more dilated than the RV. Left apical four-chamber view of a dog with tricuspid dysplasia, demonstrating marked RA dilatation and mild to moderate RV dilatation. It can be difficult to appreciate specific abnormalities of the tricuspid apparatus. Note that there is also some pleural effusion, seen between the probe and the apex of the heart. Colour flow mapping shows a turbulent jet of flow back into the RA during systole. LA = Left atrium; LV = Left ventricle; RA = Right atrium; RV = Right ventricle.
Image of 26.28
26.28 Tetralogy of Fallot consists of PS with concentric RV hypertrophy. There is also a subaortic VSD, which is usually large, and a malaligned (over-riding) aorta. The pulmonary trunk is usually also hypoplastic. Right-to-left flow across the VSD, due to the high RV pressure associated with PS, results in desaturated blood entering the aorta, with cyanosis, hypoxaemia and polycythaemia. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission
Image of 26.30
26.30 Echocardiography of tetralogy of Fallot. Right parasternal long-axis five-chamber view of a Border Collie. The aorta is malaligned, over-riding the septum, and a high VSD is present. Right parasternal short-axis view obtained at the level of the heart base and optimized for the RVOT. The pulmonic valves are thickened and stenotic, and the main pulmonary artery is hypoplastic. Ao = Aorta; LV = Left ventricle; RV = Right ventricle; PA = Pulmonary artery; RVOT = Right ventricular outflow tract.
Image of 26.31
26.31 Right parasternal four-chamber view of a Weimaraner with an endocardial cushion defect. There is a primum-type ASD (measuring >2.3 cm) over the atrioventricular annuli. The atrioventricular valves are in the same plane. Concurrent pulmonary hypertension also exacerbates the right heart enlargement.
Image of 26.32
26.32 Vascular ring anomalies. Lateral thoracic radiograph of a 6-week-old Jack Russell Terrier with regurgitation of solid foods since weaning. Barium sulphate mixed with canned food was fed. Megaoesophagus cranial to the heart base, with a relatively normal oesophagus coursing caudally from the heart to the stomach, was identified. A PRAA was confirmed at thoracotomy, with oesophageal entrapment between the heart base, pulmonary trunk on the left, and the ligamentum arteriosum. 3D reconstruction from a CT angiographic study in a dog with an unusual vascular ring anomaly (PRAA with retroesophageal left subclavian artery). This is a view from the left, showing the PRAA, but with the left subclavian artery also resulting in partial oesophageal obstruction. Additional vascular abnormalities are evident, with the carotids arising directly off the aortic arch. (Courtesy of F. McConnell.)
Image of 26.33
26.33 Right parasternal modified long-axis view of a dog with a PLCVC (arrowed). Left apical four-chamber view. The left cranial vena cava (arrowed) normally enters into the coronary sinus; the dilated coronary sinus courses around the left atrioventricular groove and enters the RA. LV = Left ventricle; RA = Right atrium; RV = Right ventricle.
Image of 26.34
26.34 Lateral thoracic radiograph of a dog following oral administration of barium liquid. Note that much of the intestines are visible within the pericardium.

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