Diseases Of The Cardiovascular System II PDF 2024

Diseases of the Cardiovascular System II: Congenital Diseases Dr Paul Pollard MVB Cert AVP(VC) MSc Vet Ed SFHEA MRCVS [email protected] PollEv.com/paulpollard090 Learning Objectives » Review cardiac anatomy, foetal circulation and cardiac imaging modalities ✔ » Understand cardiac mur...

Diseases of the Cardiovascular System II: Congenital Diseases Dr Paul Pollard MVB Cert AVP(VC) MSc Vet Ed SFHEA MRCVS [email protected] PollEv.com/paulpollard090 Learning Objectives » Review cardiac anatomy, foetal circulation and cardiac imaging modalities ✔ » Understand cardiac murmur grading and recognise common murmur types ✔ » Review both common and uncommon congenital defects and how they influence blood flow patterns » Understand and describe the pathophysiology, clinical presentation, diagnosis, treatment/management and prognosis for common congenital cardiac conditions: Patent ductus arteriosus Pulmonic stenosis Subvalvular aortic stenosis Atrial and ventricular septal defects #universityofsurrey 2 Congenital Heart Disease » Any functional or anatomical abnormality that is present at birth – can be caused by genetic or non- genetic factors » Sometimes these abnormalities are not discovered until later in life – but would still have been present at birth » Most common congenital heart diseases: Dogs: Cats: Patent ductus arteriosus Ventricular septal defects Subaortic stenosis Atrioventricular valve dysplasias Pulmonic stenosis Mitral valve dysplasia Ventricular septal defects #universityofsurrey 3 Congenital Heart Disease » Most puppies and kittens are completely fine! » Innocent or pathological murmur? » Additional signs can develop with severe defects: Failure to grow at a normal rate or to a normal size Exertional fatigue Abdominal distension (ascites) Episodic weakness or syncope Cyanosis » Indications for additional work-up: Suspicion of congenital heart disease Emotions of client Breeder information #universityofsurrey 4 Congenital Heart Disease Classification » Volume Overload PDA (L-R shunt) VSD (L-R shunt) ASD (L-R shunt) Mitral valve dysplasia Tricuspid dysplasia » Pressure Overload Valvular pulmonic stenosis Subvalvular aortic stenosis » Cyanotic Tetralogy of Fallot Large PDA/VSD/ASD with R-L shunting #universityofsurrey 5 How do you think the heart remodels for volume overload and for pressure overload? #universityofsurrey 6 Less Common Congenital Conditions » Right-sided Aortic Arch » Atrial Septal Defect Ostium secundum (most common) Ostium primum Sinus venosus (least common) » “Reversed” R – L shunting Patent Ductus Arteriosus » Aortic-Pulmonary Window #universityofsurrey 7 Less Common Congenital Conditions » Ebstein’s Anomaly » Double-outlet right ventricle » Cor triatriatum Dexter (R) Sinister (L) » Tetralogy of Fallot #universityofsurrey 8 Patent Ductus Arteriosus » Ductus arteriosus connects the main pulmonary artery to the aorta in the foetus » After birth: First breath opens lungs and decreases pulmonary vascular resistance Flow reverses through DA to become L-R Rise in oxygenated blood through DA Increased paO2 inhibits local prostaglandin release Smooth muscle constricts DA closes » Failure to close in dogs due to lack of smooth muscle Most common result is a tapered, funnel-shaped vessel with L-R shunting from aorta to pulmonary artery #universityofsurrey 9 Patent Ductus Arteriosus » Pathophysiology Flow through PDA Pulmonary overcirculation Increase in pulmonary venous return and therefore left end-diastolic volume Increased LV stroke volume LV remodels with eccentric hypertrophy Results in an increased systolic aortic pressure Volume Overload = Eccentric Hypertrophy #universityofsurrey 10 Patent Ductus Arteriosus » One of the most common congenital diseases in the dog » Increased prevalence in many breeds indicates genetics are likely involved in the pathogenesis » Signalment Cavalier King Charles Spaniels, Poodles, German Shepherds, Springer Spaniels, Collies, Shetland Sheepdogs, Pomeranians More common in females (3:1) PDA in cats is very rare #universityofsurrey 11 Patent Ductus Arteriosus » Clinical Signs https://depts.washington.edu/physdx/audio/pda.mp3 High grade, continuous, “machinery” murmur, loudest over left heart base Hyperkinetic “water hammer” pulses caused by increased aortic systolic pressure and decreased aortic diastolic pressure Precordial impulse felt over a larger area 2/3 with present with congestive heart failure (cardiogenic lung oedema) within 1 year if not treated » Diagnosis Auscultation Ettinger, 2017 #universityofsurrey 12 Patent Ductus Arteriosus » Other findings: » ECG Patterns of LV enlargement (tall, wide R wave) and possible left atrial enlargement (wide P waves) +/- arrhythmias » Thoracic radiography Left heart enlargement Pulmonary overcirculation Aortic bulge +/- pulmonary oedema #universityofsurrey 13 Patent Ductus Arteriosus Right long axis view Ductus visible at L base » Echocardiography Left atrial and ventricular enlargement May see ductus Doppler shows continuous blood flow Used for planning surgery Colour flow Doppler Continuous wave Doppler #universityofsurrey 14 Patent Ductus Arteriosus » Treatment (L-R) Ligation of ductus via thoracotomy or interventional catheterisation procedure (via femoral artery, minimally invasive) Amplatz Canine Duct Occluder or thrombogenic coil Provides immediate decrease in left sided volume overload, gradual reversal of eccentric hypertrophy over time and an excellent prognosis Both technically demanding options Stabilise if presenting in CHF prior to anaesthetic #universityofsurrey 15 Patent Ductus Arteriosus Curable! #universityofsurrey 16 Reverse Patent Ductus Arteriosus – R-L Shunting » Very large PDA that often does not taper » Often no murmur » Clinical signs: Differential cyanosis (pink MMs in the cranial half of the body, cyanotic MM in caudal half) – may only be apparent after exertion Secondary polycythaemia – hypoxaemic blood to kidneys increases EPO » Closure of PDA is contraindicated R-L shunt due to high pulmonary pressure so closure would increase pulmonary pressure even more! » Medical management to dilate the pulmonary artery to reduce pressure and manage symptoms #universityofsurrey 17 Reverse Patent Ductus Arteriosus Not Curable #universityofsurrey 18 Learning Objectives » Review cardiac anatomy, foetal circulation and cardiac imaging modalities ✔ » Understand cardiac murmur grading and recognise common murmur types ✔ » Review both common and uncommon congenital defects and how they influence blood flow patterns ✔ » Understand and describe the pathophysiology, clinical presentation, diagnosis, treatment/management and prognosis for common congenital cardiac conditions: Patent ductus arteriosus ✔ Pulmonic stenosis Subvalvular aortic stenosis Atrial and ventricular septal defects #universityofsurrey 19 Stenosis #universityofsurrey 20  Normal Pulmonic Stenosis Type A » Varying degrees of obstruction to the right ventricular outflow tract; lesions may be valvular (most common), subvalvular or supravalvular Valvular Type B Type A – reduced ostium size Type B – reduced ostium and hypoplastic Subvalvular – rare – due to coronary artery anomaly (English Bulldogs and Boxers particularly) » Breed predispositions: Boxers, Beagles, Bull Mastiffs, Bulldogs, Cocker Spaniels, Miniature Schnauzers, Terriers and Chihuahuas » Uncommon in cats #universityofsurrey 21 Pulmonic Stenosis » Pathophysiology Fibrous ring of tissue located in the RVOT Concentric hypertrophy is proportional to severity of stenosis Pressure Overload = Concentric Hypertrophy #universityofsurrey 22 Pulmonic Stenosis » Clinical Findings: Asymptomatic > syncope > CHF > sudden death – depends on severity of stenosis Auscultation: systolic ejection type, harsh murmur loudest over left heart base Ddx: Aortic stenosis, innocent murmur https://depts.washington.edu/physdx/audio/ps.mp3 Murmur intensity correlates with severity of stenosis Normal femoral pulses +/- jugular pulsation » ECG Right atrioventricular enlargement (deep S waves in leads I, II and III, tall P waves) Can be normal in mild cases https://www.vetstream.com/treat/canis/diseases/pulmonic-stenosis #universityofsurrey 23 Pulmonic Stenosis » Radiography Right atrioventricular enlargement; post stenotic bulge of the pulmonary artery #universityofsurrey 24 Pulmonic Stenosis » Echocardiography Concentric hypertrophy of the right ventricle Structural abnormalities of the pulmonic valve and right ventricular outflow tract #universityofsurrey 25 Pulmonic Stenosis Pressure differential between » How severe is it? RV and PA can be determined non-invasively using Doppler ΔP = 4v2 Modified Bernoulli equation #universityofsurrey https://ecgwaves.com/topic/the-bernoulli-principle-and-calculation-of-pressure-difference-pressure-gradient/ 26 Pulmonic Stenosis http://www.leadervet.com/specialist-articles-1/pulmonary-hypertension-rdvm 80 mmHg: severe stenosis – high risk of https://www.cvcavets.com/diseases-conditions/pulmonic-stenosis/ developing problems #universityofsurrey 27 Pulmonic Stenosis » Treatment If the stenosis is severe, or there are clinical signs in a dog with moderate stenosis: Medical management involves beta-blockers (less ideal alternative) Minimally invasive balloon valvuloplasty Contraindicated when coronary artery anomaly Various surgical treatments via thoracotomy » Prognosis Depends on the severity of the stenosis, outcome of surgery (pressure drop of 50% or more), presence of CHF #universityofsurrey 28 Aortic Stenosis » Varying degrees of obstruction of the left ventricular outflow tract; lesions may be subvalvular (most common), valvular or supravalvular » Important disease in large breed dogs » Breed predisposition Boxers, GSD, Newfoundlands, Rottweilers and Golden Retrievers » Very rare in cats #universityofsurrey 29 Subvavlular Aortic Stenosis » Pathophysiology Fibrous ring of tissue located in the LVOT Concentric hypertrophy is proportional to severity of stenosis Pressure Overload = Ettinger, 2017 Concentric Hypertrophy #universityofsurrey 30 Subvalvular Aortic Stenosis » Clinical Findings: Asymptomatic > CHF > sudden death – depends on severity of stenosis Auscultation: systolic ejection type, harsh murmur loudest over left heart base, radiating up the carotid arteries in severe cases https://depts.washington.edu/physdx/audio/as-early.mp3 Ddx: Pulmonic stenosis, innocent murmur Murmur intensity correlates with severity of stenosis Weak femoral pulses +/- irregular pulses » ECG Often normal Can indicate left ventricular enlargement (increased R wave and QRS duration); myocardial hypoxia (ST segment depression), ventricular arrhythmias #universityofsurrey 31 Subvalvular Aortic Stenosis » Thoracic radiographs Often normal Left ventricular enlargement, post-stenotic dilation of aorta https://www.intechopen.com/chapters/66972 #universityofsurrey 32 Subvalvular Aortic Stenosis » Echocardiography Concentric LV hypertrophy Subvalvular obstructive lesion Post stenotic dilation of the aorta High velocity of blood across valve #universityofsurrey 33 Subvalvular Aortic Stenosis » Treatment Mild – no treatment Moderate or severe stenosis Atenolol: Beta-blocker – decreases myocardial oxygen consumption, slows maximum HR, improves diastolic filling Balloon dilation – no evidence to suggest it improves survival over atenolol Surgery – no evidence to suggest it improves survival over atenolol #universityofsurrey 34 Atrial (ASD) and Ventricular Septal Defects (VSD) » Common in both dogs and cats (VSD is the most common congenital cardiac abnormality in cats) » Can occur as a component of a more complex lesion (e.g. Tetralogy of Fallot) » Types of ASD: Ostium primum (lower ASD) Ostium secundum (high ASD) » A patent foramen ovale is not a true ASD – atrial septum forms normally but the walls of the foramen are pushed apart, usually by increases in right atrial pressure » A VSD is almost always high septal https://www.youtube.com/watch?v=5DIUk9IXUaI&t=155s #universityofsurrey 35 Atrial and Ventricular Septal Defects » Pathophysiology Small Defects (“good”) Large Defects (bad) AKA Restrictive AKA non-restrictive Shunting of blood will depend on pressure Shunting depends on relative vascular resistance difference between two chambers of systemic and pulmonary vasculature Shunting will be L → R If severe can lead to shunt reversal (R → L) In case of ASD: mild right heart overcirculation In case of ASD: more significant right heart overcirculation > eccentric hypertrophy In case of VSD: blood flows directly into RV In case of VSD: volume overload of left heart > outflow tract, no/little cardiac remodelling (if so: blood shunts into RV outflow tract and pulmonary mainly left heart artery > risk of LHS CHF #universityofsurrey 36 Atrial and Ventricular Septal Defects » Clinical signs depend on the size of the defect ASD VSD No murmur, or soft murmur, over the pulmonic Murmur over the right apex valve Small defects – good prognosis The louder the murmur, the smaller the defect, the better the prognosis The larger the defect the more volume overload of A large defect can lead to LHS CHF the right heart – risk of RHS CHF A large defect could lead to R – L shunting over A large defect can cause no murmur, equalisation time - cyanosis of the RV and LV pressures – ultimately R – L shunting and cyanosis #universityofsurrey 37 Atrial and Ventricular Septal Defects » Echocardiography is the most important tool for diagnosis in these conditions Allows visualisation of the shunt, patterns of hypertrophy » Animals with small defects usually have a normal life with no clinical signs or need of intervention » Intervention and surgical procedures have been described, control of CHF needed if present #universityofsurrey 38 Conclusion » Congenital cardiac disease is common in the dog and less common in the cat » Do not miss a PDA! » Stenosis causes: Pressure overload Concentric hypertrophy Forward failure » Leaks and holes cause: Volume overload Eccentric hypertrophy Backward failure » Physical examination findings should narrow your differentials » Echocardiography to confirm #universityofsurrey 39 Further Reading » Cardiovascular chapters of Ettinger’sTextbook of Veterinary Internal Medicine (8th Edition) » Notes on Cardiorespiratory Diseases of the Dog and Cat (2nd Edn). Mike Martin and Brendan Corcoran » Small Animal Cardiovascular Medicine (Kittleson and Kienle) - only available on VIN online (free registration for students) » BSAVA Manual of Canine and Feline Thoracic Imaging. Tobias Schwarz and Victoria Johnson. » https://viper.vetmed.ucdavis.edu/public/cardio_kittleson/cases/ #universityofsurrey 40  PollEv.com/paulpollard090 Questions? Please use the discussion forums on SurreyLearn [email protected] 41