Congenital Heart Defects Flashcards by Eloise Newsom

What is congenital heart disease?

Malformations of the heart and great vessels that are present at birth
Caused by altered or arrested embryonic development of the rudimentary heart
○ Leads to potentially gross anatomical alterations

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What is an innocent murmur?

A heart murmur not caused by underlying heart disease
Caused by:
* High heart rate
* High velocity of blood flow
* Changes turbulence

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What is a heart murmur?

Abnormal heart sound caused by turbulent blood flow within heart

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PMI

Point of Maximal Intensity

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Signs of an innocent murmur

Low grade murmur (1/2)
PMI Left heart base
Mid-systolic
Varying intensity with rate
Minimal radiation
Usually resolve within 6 months

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Common abnormalities on clinical exam of congenital heart disease

Arterial pulse
○ Hyperkinetic pulse
○ Hypokinetic pulse
Mucous membrane colour
Precordial impulse (palpable)

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Causes of hyperkinetic pulse

Abnormal diastolic run off of aortic blood
Patent ductus arterioles
Severe aortic regurgitation

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Causes of hypokinetic pulse

Left ventricular obstruction
Aortic stenosis
Poor LV output

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What diagnostics are useful/give clues in diagnosing congenital heart disease?

History
CLinicala Exam
ECG
Thoracic Radiographs

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What diagnostics are definitive clues in diagnosing congenital heart disease?

Echocardiography

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Which structures can fail to develop properly?

Mitral valve
Tricuspid valve
Aortic valve
Pulmonary valve
Intra atrial septum
Intra-ventricular septum
Ductus arteriosus

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Which are the most common congenital heart defects?

Aortic stenosis (AS)
Patent ductus arteriosus (PDA)
Pulmonic stenosis (PS)
Ventricular septal defect (VSD)

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What is aortic Stenosis?

Narrowing of the aorta

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What are the types of aortic stenosis

Subaortic stenosis
Valvular aortic stenosis
Supra-aortic stenosis

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Which is the most common form of aortic stenosis?

Subaortic stenosis

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Common signalment of subaortic stenosis

Boxers
Newfoundlands
Golden retrievers
Syncope
Lethargy
Exertional weakness

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What kind of murmur does AS have?

Harsh systolic ejection murmur
* Exercise/excitement may increase intensity of murmur
PMI at aortic valve (base of heart
Precordial thrill at left base
Radiates to right base

(May have diastolic murmur depending on severity)

Findings of aortic stenosis on echocardiogram

Increased speed at which blood crosses aortic valve
* High speed is due to high pressure

Thickening of LV due to high pressure
* Can cause narrowing of LV

Treatment for AS

Beta-blockers to reduce oxygen demand
* Atenolol
Catheter through femoral artery into stenosis and inflate balloon

If mild, often doesn’t need treatment

Types of pulmonic stenosis

1 - Infundibular
2 - Sub-valvular
3 - Valvular
4 - Supra-valvular
5 - Anomalous coronary artery

Most common type of pulmonic stenosis

Valvular
* affects leaflets of annular valve

Signalment of pulmonic stenosis

Brachycephalics
Terriers

Type of murmur in pulmonic stenosis

High frequency systolic ejection murmur
PMI left heart base

(Same as AS)

Clinical signs of PS

RCHF (pleural effusion/ascites)
Syncope
Exercise intolerance
Sudden death in severe cases

Findings of PS on clinical exam

Prominent R apical beat PMI of systolic murmur on left heart base Radiates cranially and ventrally Prominent jugular pulses

Findings of PS on echocardiogram

Enlarged right atrium * Should be significantly smaller in healthy animal Turbulence in right side of heart

Findings of PS on radiography

RHS more cranial and enlarged Very radiolucent lung fields * Less blood flow to lungs so vascular pattern disappears

Treatment of PS

Same as AS Berablockers (Atenolol) to prevent arrhythmias and reduce work of RV Catheter through femoral artery into stenosis and inflate balloon

What is the ductus arteriosus

Shunt between aorta and pulmonary artery present in-utero and shortly after birth Lungs not yet in use

What is PDA?

Patent ductus arteriosus Blood shunts from aorta to pulmonary artery (Leaves LV via aorta, enters pulmonary artery to lungs, returns via pulmonary vein to LA) Seen in very young animals

Describe the PDA murmur

Continuous murmur PMI over left base but very cranial and dorsal (in axilla) Usually loud

Result of PDA

Massive LHS volume overload leads to stretched LA and LV Hyperkinetic pulses

Treatment for PDA

Surgical ○ Thoracotomy ○ Ligate PDA ○ Major risk of haemorrhage Occluder ○ Catheter through femoral artery to PDA ○ Disc sits either side and blocks PDA

Where are ventricular septal defects most common?

High in the membranous part of septum Just below aortic valve and under tricuspid leaflet

What is a VSD?

Ventricular septal defect Allows blood to flow from left to right ventricle (Higher pressure in left)

Result of VSD

Flow from left to right ventricle Basically skipping out aorta Leads to overload of pulmonary trunk, pulmonary circulation, LA and LV Moderate/large VSD results in LCHF (Pulmonary oedema)

Small VSD findings

Very loud systolic murmur Left base (LA) Right apex (RV) Often tolerated well and not an issue

What should you do if you find murmur in a puppy/kitten?

If grade 3 or below, leave for 6 months and recheck Loud doesn't always mean bad ALWAYS RECCOMEND ECHOCARDIOGRAPHY

What is the tetralogy of fallot

4 different defects: * Pulmonic stenosis * Large VSD * Right ventricular hypertrophy * Dextropositioning of aorta Results in right to left shunt

Clinical signs of tetralogy of fallot

Cyanosis Polycythemia Weakness Lethargy Dyspnoea