Congenital heart disease Flashcards
Define congenital heart disease
Malformations of the heart and great vessels that are present at birth
CHD occurs due to altered or arrested embryonic development of the rudimentary heart leading to potentially gross anatomical alterations
Compare innocent murmurs to those heard with CHD
Grade:
- Innocent murmur= low grade (I-II/VI)
- CHD= II-VI
Timing:
- Innocent= mid-systolic
- CHD= depends on condition but tend to be longer in duration
PMI:
- Innocent= left heart base
- CHD= depends on condition
Radiation:
- Innocent= minimal
- CHD= depends on pathology
Variability:
- Innocent= varying intensity with heart rate
- CHD= generally non-variable
Resolution:
- Innocent= usually resolve by 6 months
- CHD= no resolution
What abnormalities might be found with the arterial pulse in patients with CHD?
Hyperkinetic pulse (waterhammer):
- Abnormal diastolic run off of aortic blood
- PDA/ severe aortic regurgitation
Hypokinetic pulse:
- Left ventricular/ outflow tract obstruction
- Aortic stenosis or poor left ventricular output
What should you do in practice when you hear a murmur in a puppy or kitten?
o If loud (grade 3+) more likely to be a congenital anomaly, but loud does not necessarily mean bad (think small VSD)
o If < grade 2 then could be innocent – reassess at 3 and 6 months
o Return to breeder and get money back (rarely done, bond formed)
o Ultimately one can only assess nature and severity of lesions with a full Doppler echocardiogram
Name some common types of CHD?
- Aortic stenosis (AS)
- Patent ductus arteriosus (PDA)
- Pulmonic stenosis (PS)
- Ventricular septal defect (VSD)
What are the 3 types of aortic stenosis?
Sub-aortic stenosis (common)
Valvular aortic stenosis (uncommon)
Supra-valvular (rare)
What is sub-aortic stenosis?
Sub-valvular narrowing caused by a fibrous or fibromuscular ring
+/- mitral dysplasia as well
What is valvular aortic stenosis?
Narrowing of the valve itself
Why are myocardial ischaemia and fibrosis common sequalae to aortic stenosis?
Due to narrowed intramural coronary arteries and inadequate myocardial capillary density as the hypertrophy progresses
(These factors lead to an increased risk of ventricular arrhythmias leading to weakness, syncope, left-sided congestive heart failure and sudden death)
What may be heard on auscultation of aortic stenosis?
- Harsh systolic ejection murmur, PMI aortic valve
- Precordial thrill at the left heart base
- Radiates to right heart base
- +/- diastolic murmur depending on pressure and severity of AI
What may be seen on radiographs of aortic stenosis?
May be normal (concentric hypertrophy so external diameter of the heart not changed much)
Left sided cardiomegaly
Post-stenotic dilation in the ascending aorta
ECG can be normal or show evidence of LV hypertrophy
Echocardiographic features depend on the severity of aortic stenosis but what might be seen?
- Concentric LVH
- Rounding of LV
- Post-stenotic dilation
- +/- aortic regurgitation
- +/- LAE
- +/- MR
- Hyperechoic, hypertrophied PM
- Fibrous ring is SAS/ abnormal valve etc.
What are the five types of pulmonic stenosis?
Infundibular
Sub-valvular pulmonic stenosis (uncommon)
Valvular pulmonic stenosis (common)
Supra-valvular (rare)
Anomalous coronary artery (coronary artery loops around base of pulmonary artery)
What may be found on clinical examination of an animal with pulmonic stenosis?
- Many cases are asymptomatic on presentation, clinical signs depend on severity of lesion
- Right sided heart failure, syncope, exercise intolerance
- Sudden death does occur in some severe cases
- Prominent right apical beat
- PMI murmur left heart base (high frequency systolic ejection murmur)
- Radiation cranially and ventrally
- Prominent jugular pulses
What are radiographic signs of pulmonic stenosis?
- Right sided enlargement due to right ventricular hypertrophy
- Pulmonary trunk bulge at 1 o’clock position on the DV view
- Dilation of caudal vena cava in some dogs
What are echo features of pulmonic stenosis?
- RV hypertrophy and enlargement
- Flattening of the IVS with high right sided pressures
- Right atrial enlargement
- Abnormal pulmonic valve often thickened and fused
- Post-stenotic dilation of the pulmonary trunk
- Right sided congestive heart failure
What is a patent ductus arteriosus?
Blood shunting from aorta into pulmonary artery due to failure of closure of the ductus (should occcur within hours after birth)
Animals with inherited PDA have histologically abnormal ductal walls that are unable to constrict
Leads to eccentric hypertrophy
Describe a murmur heard with PDA
Continuous murmur
Best heard over the left heart base but very cranial and dorsal (in armpit)
Very important to detect as potentially curable
What may be found on clinical examination of animals with PDA?
- Continuous machinery murmur PMI left heart base
- Hyperkinetic pulses
- Volume overload leads to a large haemodynamic burden on the left ventricle which fails
- After 12 months many dogs will progress into left sided congestive heart failure and show typical clinical signs
What may be found on ECG of a heart with PDA?
Wide, tall P waves
Tall R waves
Tachycardia if in heart failure
What might be found on echocardiography of PDA?
- volume overloaded LA and LV (due to pulmonary overcirculation)
- MR if mitral annulus is stretched
- dilation of pulmonary trunk
- doppler studies show continuous turbulent flow entering the pulmonary artery
Where are ventricular septal defects usually located in dogs?
High in the membranous part of the septum just below the aortic valve and under the tricuspid leaflet (perimembranous)
Where does blood shunt with ventricular septal defects?
Left to right side—shunts into pulmonary circulation
Leads to volume overload of the pulmonary trunk, pulmonary circulation, LA and LV
(Usually high enough up in dogs that doesn’t cause right sided enlargement because blood goes straight into pulmonary artery)
What are the clinical signs of VSDs?
Most dogs are asymptomatic but clinical signs depend on the size of the defect
Exercise intolerance, LCHF
Do VSDs cause murmurs? If so, where is the PMI?
Yes- systolic murmur
PMI cranial right sternal border
What can be seen on radiography of an animal with a VSD?
Depends on the size of the lesion
- pulmonary overcirculation
- cardiomegaly, mainly left-sided although right-sided enlargement as well if pulmonary hypertension occurs
- LCHF depending on severity
What can be seen on an ECG of an animal with a VSD?
Can have splintered QRS complexes suggested of an interventricular conduction disturbance
Right sided enlargement pattern
What can be seen on echocardiography of an animal with a VSD?
- Left sided volume overload
- MR if mitral annulus stretch
- Defect can be seen in most cases
Name some other examples of congenital heart disease
Atrial septal defect Mitral dysplasia Tricuspid dysplasia (young labs esp.) Endocardial cushion defects (cats)
What congenital heart diseases can dogs have?
AS
PDA
PS
VSD
What congenital heart diseases can cats have?
Endocardial cushion defect
TD
MD
