4. Congenital Disorders Of The Heart Flashcards
Congenital heart defects - definition
• Congenital heart defects = born with them, present from birth
○ These must be very closely monitered but don’t mean that patients die sooner
○ Detection has been possible for ~25 years – prenatal ultrasound
○ Patients may have to see their cardiologists from when they are born until they die
Prenatal detection
Via ultrasound
—> By week 8 post-conception cardiogenesis is complete
- Congenital abnormalities in cardiac structure are typically screened for a 20 weeks gestation
- Most defects which permit 6 months of intrauterine life = live offspring at full term (compatible with life)
Foetal echocardiogram
Ultrasound of baby heart
4-chamber view
–Symmetry in size of all four chambers
– Left vs right morphology
– Valve morphology and function
– Intracardiac shunts (ASD’s difficult to detect)
– Pulmonary venous return
– Pericardial effusion = accumulation of pericardial fluid
• Outflow tracts
– Origins of PA and aorta from RV and LV, respectively
• LAV
– Aortic and ductal arches
• 3-vessel view
– Entry of SVC and IVC into RA
4 causes of congenital heart defects
• Genes
○ Turners syndrome, marfan’s syndrome = caused by one gene
○ Other defects are caused by multiple genes
• Environment
• Drugs
○ Not just recreational drugs but also alcohol
• Maternal infections
○ Rubella – deafness and intercardiac problems
Congenital heart defects arise from many diverse aetiologies
• Can also occur before patient even realises they are pregnant
2 types of congenital heart defects
- Acyanotic
* Cyanotic
Acyanotic - definition
○ No cyanosis of mucous membranes
• Cyanotic - definition
○ Patient is cyanotic – blue purple discolouration of mucous membranes in mouth, lips toes etc
Acyanotic defect examples
Left to right shunts
- atrial septal defects
- Ventricular septal defects
- patent ductus arteriosus
Obstructions
- congenital aortic stenosis
- pulmonic stenosis
- coarctation of aorta
Cyanotic defects-examples
Tetralogy of fallot
Transposition of the great arteries
Eisenmenger syndrome
Anatomy of foetal heart
Foramen ovale (fetal shunt)
• Move blood from RA to LA
• Oxygenated blood bypasses lungs and goes to systemic circulation
• Occurs due to fact that pressure on right side > left side pressure
• So blood moves down pressure gradient from high pressure RA to low pressure left side
When a baby takes its first breathe when born
• Pressure gradient reverses so left pressure> right pressure
• Closes septum primum against septum secundum to seal foramen ovale
Atrial septal defect - definition
Acycanotic
→ persistent opening of atrial septum wall
Classes
Primum ASD (15%) − Superior sinus venosus defect (5%) − Inferior sinus venosus defect (<1%) − Unroofed coronary sinus (<1%)
Atrial septal defect - pathophysiology
Acycanotic
• = defect where blood flows from LA to RA and out of the right outflow tract
1. Blood moves into LA but instead of all the blood going to LV like normal, some of it it goes to RA 2. Blood passes across atrial septal defect from LA to RA 3. Blood goes from RA to RV and out of pulmonary artery
• Simple shunt – left-to-right because of higher compliance of RV
− Causes RV volume overload and pulmonary hypertension (9-35% of patients with Secumdum ASD).
• Shunt volume depends on RV/LV compliance, defect size and LA/RA pressure.
Atrial septal defect - symptoms
Acycanotic
• Often undiagnosed until adulthood – 25% clinically silent in childhood
– Reduced functional capacity
– Shortness of breath upon exertion
– Palpitations
– Repeated respiratory infections
Atrial septal defect - physical examination
Acycanotic
- Parasternal heave – RV enlargement
- As increased blood volume moves into RV it is stretched and enlarged overtime
- Can be palpated over sternal angle – lifting effect due to large RV lifitn sternum as heart beats
• Murmur at upper-left sternal border – due to increased blood flow across PV (pulmonary valve)
• Murmur at lower-left sternal border – increased flow across TV (tricuspid valve)
○ More blood than normal passes from RA to RV
Atrial septal defect - treatment
Acyanotic
- only surgical repair if volume is significantly large
Patent foramen ovale
—> opening in foramen ovale
• This is not a true atrial septal defect, as no septal tissue is missing, it is just a persistence of foetal anatomy
• Clinically silent when LA pressure is greater than RA pressure - generally can overcome patency so no blood volumes pass over
• Clinically relevant in states of increase RA pressure when RA pressure > LA pressure
– Pathological right-to-left shunt
Acyanotic – ventricular septal defects
Definition
—-> abnormal openings in inter ventricular septum – wall between LV and RV
—> blood will still move normally through the heart in these defects but some volumes of blood will follow the defect
• Can occur anywhere in intraventricular septum
Membranous (70%)
– Muscular (20%)
– Aortic or adjacent to AV valves (rare)
– Singular defects most common but multiple defects do occur
Acyanotic – ventricular septal defects
Pathophysiology
- Blood enter LA
- Blood moves to LV
- Some blood passes through the venticular septal defect to RV
○ on size of defect in ventricular septal defects
○ Compliance of receiving chamber (right ventricle
○ Pressure difference
− Small VSD’s = defect offers more resistance that pulmonic and systemic circulations therefore small left-to-right shunt
− Large VSD’s = low resistance relative to low-ish pulmonary and high-ish systemic resistances, therefore, RV, pulmonary circ., LA and LV have volume overload.
Acyanotic – ventricular septal defects
Symptoms
Most common CHD
– Small VSD’s are symptom-free
– Large VSD’s develop symptoms of heart failure
– Repeated respiratory infections
Acyanotic – ventricular septal defects
Physical examination
• Harsh holosystolic murmur (mumur throughout all of systoel)– left sternal border
○ As systole is contraction – causes blood to move across VSD = murmur
• Systolic thrill palpated over same area
○ Blood volumes squeezed through VSD
• Apical mid-diastolic rumble murmur – increased mitral valve flow
○ increased flow across this valve
Acyanotic – ventricular septal defects
Treatment
- Most undergo spontaneous closure overtime
- Larger ones need surgical treatment
Acyanotic – patent ductus arteriosus
Definition
• Persistant communcication between proximal left pulmonary artery and descending aorta
○ Sometimes this doesn't close sufficiently – patent ductus arteriosus ○ So some blood can move from aorta across patent ductus arteriosus into pulmoary artery and pulmoary circulation
Acyanotic – patent ductus arteriosus
Presentation
Small duct
– no LV left ventricular vol. overload and normal PAP (pulmonary arteriole pressure)
• Moderate PDA
– Predominant LV vol. overload
• Moderate PDA
– Predominant PAH
• Large PDA
– Eisenmenger physiology
Anatomy - normal ductus arteriosus
- Ductus arteriosus in utero = moves blood from pulmonary artery up into aorta - so blood is pumped to systemic circulation
- Moves venous blood from IVC and SVC to systemic ciruclation and placenta for gas exchange
Acyanotic – patent ductus arteriosus
Pathophysiology
—> Normally closes due to constriction due to sudden rise in O2 tension after birth.
• If it doesn’t close sufficiently = Left-to-right shunt with LV volume overload. In moderate and large PDA’s, pulmonary pressure is increased.
− Flow depends on haemodynamics of ductus (length/radius/resistance)
− LA, LV and pulmonary circ. vol. overload
• Large PDA’s may develop Eisenmenger’s physiology
Acyanotic – patent ductus arteriosus
Symptoms
• Small PDA are asymptomatic
• Large PDA
○ Heart failure with tachycardia, poor feeding, slow growth and respiratory infections
• Moderate PDA – Fatigue, dypsnea and palpitations
• AF due to LA dilatation
• If Eisenmenger syndrome develops
○ Cyanosis of feet and lower extremities but normal colouration upper extremities – as upper extremities receive oxygenated blood from aorta (proximal to PDA) but the lower extremities are supplied by descending aorta (distal to PDA)
Acyanotic – patent ductus arteriosus
Physical examination
- Continuous machine-like murmur – left subclavicular region
- Constant flow through PDA
- Cyanosis of lower extremities if Eisenmenger syndrome develops
Acyanotic – patent ductus arteriosus
Treatment
—> if it is problematic
• Constriction of ductus with prostaglandin synthesis inhibitors
• Surgical division or ligation
Acyanotic – aortic stenosis
Definition
Formation of Bicuspid leaflet structure
• Aortic valve normally is tricuspid
Obstruction of blood flow from left ventricle
Acyanotic – aortic stenosis
Presentation
• values can become stenotic and fibrotic due to Progressive stenosis due to calcification and fibrosis • Classes – Valvular – Subvalvular – Supravalvular
Acyanotic – aortic stenosis
Pathophysiology
- Thickening of aortic valve leaflets/ cusps
- More difficult for LV to move blood out across stenotic aortic valve into aorta
- Significant narrowing of valve opening between LV and aorta
- Less flow through that valve
- LV hypertrophy to meet increase ‘afterload
- Build up of pressure in LV
Acyanotic – aortic stenosis
Symptoms
• Depends on lesion severity
• In few children (10%)
– Tachycardia, tachypnea and poor feeding
• Older children
– Asymptomatic
• Adults
– Fatigue, exertional dypsnea, angina and syncope (fainting)
Acyanotic – aortic stenosis
Physical examination
• Cresendo-decrescendo murmur – loudest at base
○ Turbulent flow through stenotic aortic valve
