CVS - Congential Heart Disease Flashcards
What type of blood does the right ventricle pump? And to where?
What type of blood does the left ventricle pump? And to where?
Deoxygenated blood
To the lungs
Oxygenated blood at systemic blood pressure to aorta
Is there high or low resistance in pulmonary circulation?
Low resistance - gas exchange over a vast area, goes through really easily
What will increase pressure in the pulmonary artery and venous pressure cause?
Damage
Increased lung blood flow is not damaging
What is required and what isthe effect of a right to left shunt?
Hole and distal obstruction
Deoxygenated blood by passes the lungs
In a left to right shunt which way does blood travel?
Blood from left heart is returned to the lungs instead of going to the body
What are the two classifications of congenital heart disease?
Acyanotic (pt does not go blue)
Left to right shunts - ASD, AVD, PDA
Cyanotic Complex, right to left shunts Tetralogy of fallout Transposition of great arteries Total anomalous pulmonary venous drainage Univentricular heart
Name four shunts
Atrial
Ventricular
Atrio-ventricular
Aorto-pulmonary (ductal)
What are the effects of an atrial septal defect?
Increased pulmonary blood flow
RV volume overload
Pulmonary hypertension is rare
Eventually right heart failure
What are the effects of a ventricular septum defect?
Left to right shunt of blood
Left ventricle overload
Pulmonary venous congestion
Eventually pulmonary hypertension
What is aortic stenosis?
What gender is it most common in?
Narrowing of the valve, thickening of the muscle behind the valve
Men
What is tetralogy of fallot?
What are the effects?
Pulmonary stenosis
Ventricular septal defect
Right ventricular hypertrophy
Over-riding aorta
What are the three causes of congenital heart disease?
Genetic - Downs, Turners, Marfans Syndrome
Environmental - teratogenic its from drugs, alcohol
Maternal Infections - rubella, toxoplasmosis
How can congenital heart lesions be categorised?
Describe
Cyanotic - blue/purple discolouration of the skin and mucous membranes caused by an elevated blood concentration of deoxygenated Haemoglobin
Results from defects that allow poorly oxygenated blood from the right side to be shunted to the left, by passing the lungs.
Acyanotic - left to right shunting of blood. Cause the pulmonary artery volume and pressure to increase and can be associated with the later development of pulmonary arteriolar hypertrophy and increased resistance to flow.
What are patients with congenital heart disease susceptible to?
Infective endocarditis
What is a atrial septal defect?
What is the incidence of ASD?
Where do they occur?
What are the three types?
A persistent opening in the interatrial septum after birth that allows direct communication between left and right atria
Relatively common, 1/1500 births
Can occur anywhere along to atrial septum but most common is at the region of foramen oval called ostium secundum ASD. Results from inadequate formation of septum secundum/excessive resorption of septum primum
ASD could appear in the inferior portion of interatrial septum, adjacent to AV valves –> ostium primum defect. Results from failure of interatrial septum to fuse with the endocardial cushions
Third type = sinus venousus defect - closely related to ASD but morphologically distinct.
Patent foramen oval - related to ASD. Occurs when foramen oval doesn’t close and fuse with atrial septa after birth
Describe the Pathophysiology of ASD.
What are the symptoms?
How is the condition detected?
What would a chest X-ray and ECG show?
What are the treatments?
Oxygenated blood from the left atrium is shunted into the right atrium (but not vice versa)
Increased pulmonary blood flow
Enlargement of right atrium and ventricle
Eventually right heart failure
Infants with ASD = asymptomatic. If symptoms do occur = dyspnea on exertion, fatigue and recurrent LRTI
Adults = decreased stamina and palpitations due to atrial tachyarrthymias
Presence of a murmur on routine examination
Xray= enlarged heart ECG = right ventricular hypertrophy
Elective surgical repair - if volume hemodynamically significant to prevent heart failure
What is a ventricular septal defect?
What is the incidence of VSD?
Where do they occur?
What are the three types?
Abnormal opening in the interventricular septum
Relatively common 1.5-3.5/1000 births
Membranous (70%) and muscular (20%) portions of the septum.
Rare VSDs occur just below aortic valve or adjacent to AV valves.
Describe the Pathophysiology of VSDs.
Depends on size and relative resistance of pulmonary and systemic vasculatures.
Small VSD - defect offers more resistance to flow than pulmonary and systemic vasculature - magnitude of shunt depends on hole.
Large VSD - volume of shunt determined by relative pulmonary and systemic vascular resistances.
Increasing left to right shunt develops after birth
Left ventricle volume overload
Pulmonary venous congestion
Eventually pulmonary hypertension
What are the symptoms of VSD?
How is it diagnosed?
How does it show on an X-ray and ECG?
Small VSD = symptom free
Large VSD = congestive heart failure, poor feeding, frequent LRTI.
Can develop bacterial endocarditis.
Harsh holosystolic murmur that is best heard to the left sternal border.
Smaller defects have the loudest murmurs because of the great turbulence of flow they cause. Systolic thrill can commonly be palpated over the region of the murmur.
Xray - if small, cardiac silhouette normal. Large = cardiomegaly and prominent pulmonary vascular markings are present
ECG - left atrial enlargement and left ventricular hypertrophy
What is the treatment for a VSD?
by age 2, at least 50% of small and moderate sized VSDs undergo sufficient partial or complete spontaneous closure = intervention unnecessary
May require surgical correction of the defect in the first few months of life if child has congenital heart failure or pulmonary vascular disease.
Explain the significance of a patent ductus arteriosus
Ductus arteriosus is a vessel that connect the left pulmonary artery to the descending aorta during fetal life.
Patent ductus arteriosus results when the ductus fails to close after birth, resulting in a persistent connection between the great vessels.
Incidence 1 in 2500-5000 births
Risk factors - first trimester maternal rubella infection, prematurity and birth at high altitude.
Explain the Pathophysiology of patent ductus arteriosus
What would show on a chest X-ray and ECG
Smooth muscle of the ductus arteriosus usually constricts after birth owing to a sudden rise in blood oxygen tension and reduction in level of prostaglandins
Failure to close - results in persistent shunt between the descending aorta and left pulmonary artery
Volume of pulmonary circulation, left atrium and left ventricle increase –>. Left ventricular dilation and left sided heart failure.
Xray - enlarged cardiac silhouette, in adults calcification of ductus may be visualised.
ECG - left atrial enlargement and left ventricular hypertrophy
What is aortic stenosis (AS)?
What is the incidence?
Describe the functional importance.
Commonly caused by abnormal structural development of valve leaflets.
5 in 1000 births.
The aortic valve in AS usually has bicuspid leaflet structure instead of the normal three-leaflet configuration causing an eccentric stenosis opening through which blood is ejected.
Valvular orifice is significantly narrowed, left ventricular systolic pressure must increase to pump blood across valve into aorta. Increased pressure causes the LV to hypertrophy. High velocity blood that passes through valve may impact the proximal aortic wall and contribute to dilation of the vessel
What is coarctation of the aorta?
Who is it most likely to occur in?
What are the effects of coarctation of the aorta?
Discete narrowing of the lumen
Occurs in patients with turners syndrome (45, X)
As the aorta is narrow, the LV faces an increased after load.
Blood flow to head and upper extremities is preserved because the vessels supplying these areas usually branch off the aorta proximal to the obstruction.
Flow to the descending aorta and lower extremities may be diminished
If not corrected, compensatory alterations include:
Development of left ventricular hypertrophy
Dilation of collateral blood vessels from the intercostal arteries that bypass the coarctation and provide blood to the most distal descending aorta.
Eventually collateral vessels enlarge and can erode the under surface of the ribs
Name three left to right shunts congenital heart defects
ASD
VSD
Patent ductus arteriosus
Name 4 cyanotic right to left shunts congenital heart defects
Tetralogy of fallot
Transposition of the great arteries
Total anomalous pulmonary venous drainage
Univentricular heart
Explain the effects of a left to right shunt
Obstructive lesions - aortic stenosis, pulmonary stenosis, coarctation of the aorta, mitral stenosis
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What is tetralogy of fallot?
What are the four characteristics of this condition?
Results from a single developmental defect
Four anomalies arise that characterise the condition
- VSD caused by mal-alignment of the interventricular septum
- Subvalvular pulmonic stenosis
- Overriding aorta that receives blood from both ventricles
- Right ventricular hypertrophy
Most common form of cyanotic congenital heart disease
What is atresia of the aorta and pulmonary valve?
Tricuspid (aorta) =
No right ventricle inlet
Right to left atrial shunt of entire venous return
Blood flow to lungs via VSD
Pulmonary atresia (pulmonary valve) - no right ventricle outlet Right to left atrial shunt of entire venous return Blood flow to lungs via PDA
Can keep ducts open with drugs, cannot make new pumping chambers and cannot put new valves in
What is pulmonary stenosis?
What is the functional importance?
Obstruction to right ventricular outflow ,any occur at the level of pulmonic valve within body of right ventricle or pulmonary artery
Impairment of the RV outflow –>
Increased RV pressures and chamber hypertrophy
Severe pulmonary stenosis results in right sided heart failure
What is a hypoplastic left heart?
Left ventricle is underdeveloped
Ascending aorta very small
Right ventricle supports systemic circulation
Obligatory right to left shunt
What is transposition of the great arteries?
What is the functional importance of transposition of the great arteries?
Each vessel inappropriately arises from the opposite ventricle. E.g. Aorta from RV
Separates the pulmonary and systemic circulation by placing two circuits in parallel rather than series.
Forces desaturated blood to pass through RV and return to systemic circulation through aorta without undergoing oxygenation in the lungs
Oxygenated pulmonary venous return passes through LV and back through pulmonary artery without imparting oxygen to the systemic circulation
Extremely hypoxic, cyanotic neonate
Without intervention to mix the two circulations —> lethal condition
How is TGA compatible with life in utero?
Flow through the ductus arteriosus and foramen oval allows communication between two circulations
