Congenital Heart Diseases

• Most lethal and complex forms of congenital HD present <1 yr age
• Next most common presentation is later with a murmur in a child who is otherwise well or suffers mild exercise restriction or current chest infections

Innocent Murmurs

• Heard in 40% of 4yr olds
• 2ndry to high SV + thin chest
• Exacerabeted during fever
• ECG + CXR normal
• Dx of exclusion
• Stills murmur – midsystolic, low pitched vibratory charater, heard all over precordium but best at lower sternal edge, varies w posture + disappears w neck hyper-extension
• Continuous venous hum – heard below the clavicles, differentiated from a ductal murmur by change in murmur w posture + disappearance on pressing on the side of the neck

Atrial Septal Defects

1. Normal development of atria
a. Foramen ovale remains open during fetal devt to allow venous blood to bypass the lungs
b. After birth, the foramen ovale closes
c. In 10-20% of adults, the foarmen ovale does not entirely seal causing ↑ pulm pres (pulm HTN) – PTO (patent foramen ovale); usu asx + therefore undx
2. Defintion and Pathophysiology
a. Common – 1/1500 live births (30-40% of congenital HD in adults)
b. Blood flow LA→RA via interatrial septum
c. Large ASD (>9mm) – LA→RA shunt → vol overload of RA and RV → if left untx → HF
d. Any process the causes ↑ LV pres will worsen the L→R shunt - eg HTN
e. R heart overload of pulm vasculature → pulmonary HTN → RV failure
f. When RA pres > LA pres → reverse pres gradient across ASD + subseq R→L shunt (Eisenmengers syndr) → cyanosis
g. Types
i. Ostium secundum ASD – most common type, usu arises from enlarged foramen ovale + inadequate growth of septum secundum or excessive absorption of septum primum
1. 20% will also have mitral valve prolapse
2. Most will have no sig sxs through adulthood → 70% develop sxs by their 40’s
3. Sxs incl ↓ exercise tol, easy fatigueability, palpitation, syncope
4. Complications if untx → pulm HTN, RH failure, AF or flutter, stroke, Eisenmengers
ii. Naming of ASD
1. According to position not underlying cause
2. Ostium primum defects – close to AV valves
3. Ostium secondum defects – occur higher in the inter-atrial wall
4.
3. Presentation
a. Often asx until adulthood, although large defects may result in ↑ number of chest infections
b. Pulmonary systolic murmur due to ↑ flow across pulm valve
c. Fixed splitting of S2 and RV lift due to ↑ RV vol
d. In large shunts – diastolic murmur due to ↑ flow across tricuspid valve
4. Ixs
a. ECG
i. secundum defects have an incomplete RBBB + normal or R axis
ii. Primum defects (partial AV canal defects; common in downs) → incomplete RBBB but a superior or left axis
b. CXR – cardiomegaly and pulm.plethora
5. Tx
a. secundum defects can usu be closed via cardiac catheter around the age of 4-6 y, other defects require surgery

Ventricular Septal Defects

1. Defintion
a. Defect in ventricular septum
b. Collectively – the most common congenital heart defects
c. Ventricular septum - inferior muscular and superior membranous portion
d. Membranous portion close to AV node is most commonly affected
e. L→R shunt → continuous refluxing of blood causes vol overload and ↑ RV pres/vol → pulm HTN
2. Presentation
a. Sxs
i. Asx – small defect
ii. SOB
iii. Poor feeding + FTT in infancy
iv. Recurrent chest infections (large defect)
b. Exmn
i. Overactive precordium
ii. Ausc – pathognomonic holsystolic murmur
3. Ixs
a. ECG – LVH, RVH
b. CXR – cardiomegaly, pulmonary plethora
c. Echo
d. Cardiac catherization – more accurately measures ventr pressures

4. Tx
a. Surgical
i. Open procedures require heart-lung machine + median sternotomy
ii. Percutaneous endovascular procedures – less invasive and done on beating heart but not suitable for all pts
b. Non-surgical
i. Smaller VSDs often close on their own as the heart grows

Pulmonary Valve Stenosis

• Common – 7% of all congenital HD
• Most cases are mild
• May be an ejection systolic murmur (+/- click) in the pulmonary area, radiating to back
• Severe → present with cyanosis in newborn period (R→L shunting via PFO (patent foramen ovale)), severe RVH + strain on the ECG; mild-moderate forms just have murmur + usu asx
• ECG – post-stenotic dilation of MPA and LPA
• CXR – may show strain if severe
• Tx – catheter balloon dilation necessary

Aortic Co-arctation

1. Defintion
a. Narrowing of aorta in the area where the ductus arteriosus - diagr 2 point 3 - (ligamentum arteriosum after regression) inserts (diagr 1 – point A)
b. Types
i. Preductal coarctation – narrowing prox to ductus arteriosus (if severe, blood flow to aortal distal of narrowing dependent on patent ductus arteriosus, hence its closure can be life threatening) – diagr 2 point B
ii. Ductal coarctation – narrowing occurs at insertion of the ductus arteriosus, usu appears when the ductus arteriosus closes - diagr 2 point A
iii. Postductal coarctation – distal narrowing (even with open ductus arteriosus, blood flow to lower body can be impaired; newborn are often critically sick from birth) - diagr 2 point C
c. A
d. a
2. Clinical features
a. Arterial HTN in R arm w normal to low BP in lower extremities (classical sign)
b. Poor peripheral pulses in femoral arteries (severe cases)
c. Coarctation prox to left subclavian artery → asynchronous radial pulses, radial-femoral delay betw R arm and femoral art while no delay with left arm radial-femoral palpation
d. Coarctation distal to left subclavian artery → synchronous radial pulses, radial-femoral delay both arms
3. Ixs
a. XR - Post-stenotic dilation of aorta results in classical ‘reverse 3 sign’ – characteristic bulging of the sign is caused by dilation of the aorta due to an indrawing of the aortic wall at site of cervical rib obstruction with consequent post-stenotic dilation
b. Echo – may not be conclusive in adults and teenagers
c. MR angiography – accurate dx; in adults with untreated coarcation, blood often reaches the lower body through collaterals eg internal throracic arteries via subclavian arteries – can be seen on MR or angiography
d. ECG – LVH (due to arterial HTN)
4. Mgt
a. Conservative if asx, but may require resection of narrow segment if arterial HTN present
b. Angioplasty – in some cases to dilate the narrowed artery
c. If coarctation left untreated → arterial HTN may become permanent due to irreversible changes in some organs eg kidney

Patent Ductus Arteriosus

heart_pda

1. Normal ductus arteriosus closure
a. Fetus – ductus arteriosus (DA) = shunt connecting pulmonary artery to aortic arch
b. Allows blood to flow from RV to bypass fluid filled lungs (high resistance)
c. When the newborn takes first breath → lungs open and pulmonary pres ↓ below that of the L heart
d. At the same time, lungs release bradykinin to constrict the smooth mus wall of the DA and reduce bloodflow
e. In addition, more blood flow from pulmonary arteries to lungs → ↑ delivery of oxygenated blood to L heart further ↑ aortic pres so that blood no longer flows via the DA
f. In newborns, the DA closed within 15 hrs of birth and is completely sealed at 3 wks (due to fall in circ maternal PGs)
g. Ligamentum arteriosum = non-functional vestige of the DA remains in adult heart
2. Defintion
a. PDA is normal but reverses soon after birth
b. If PDA is persistent, there is an irregular transmission of blood between the pulmonary arteries and aortic arch
c. DA does not close but remains patent
d. Common in infants with persistent respiratory problems such as hypoxia
i. Hypoxic newborns – too little O2 reaches the lungs to produce sufficient levels of bradykinin and subseq closure of DA
ii. High occurrence in premature children (more likely to be hypoxic and thus have PDA due to underdeveloped heart/lungs)
e. In other babies – the DA remains open allowing oxygenated blood flow from aorta to pulmonary arteries → SOB, ↑ HR
f. Left untreated – infant will likely experience CHF (heart unable to meet metabolic demands of body)
3. Pres
a. Tachycardia or other arrhythmia
b. SOB or repiratory problems
c. Continuous machine like murmur upper L sternal edge due to continuous L→R flow
d. Enlarged heart
4. Ixs
a. ECG → arrhythmias, LVH
b. CXR → may reveal a patent DA, cardiomegaly
c. Echo
5. Mgt
a. Infants w/o adverse sxs may be monitored
b. Symptomatic PDA
i. Surgical – DA closed by ligation; manually tied shut or with intravascular coils/plugs leading to DA thrombus
ii. Non-surgical closure – fluid restr + PG inhibitors such as indomethacin also used successfully

Tetralogy of Fallot

tetralogyfallot

Most common cyanotic heart defect and most common cause of blue baby syndr
Four classical heart malformations that present together
1. VSD
2. Pulmonic stenosis
a. RV outflow obstr valvular stenosis
b. Stenosis result fo hypertrophy of septoparietal trabeculae
3. Over-riding aorta
a. Aortic valve not restricted to the LV – thus biventricular connections
4. RVH
a. 2ndry to incr obstruction of R outflow tr
Pathophysiology
1. TOF → low oxygenation of blood (due to mixing of oxy and deoxygenated blood in LV through VSD and preferential flow through aorta (R→L shunt)
2. Children w TOF may develop acute severe cyanosis
Symptoms
1. Low blood oxygen saturation +/- cyanosis from birth or developing first year of life
2. W/o Cyanosis → baby referred to as a pink tet
3. Other sxs → heart murmur (variable), difficulty feeding, FTT, dyspnea on exertion, clubbing, polycythemia
4. Tet spells – marked by sudden incr in cyanosis, syncope and may result in hypoxic brain injury and death
Dx
1. CXR → boot like appearance
Mgt
1. Emergency mgt of tet spells
a. Acute hypoxia treated with b-blockers
b. Morphine - ↓ ventilatory drive
c. Phenylephrine - ↑ BP
d. O2 ineffective – alveolar O2 not the problem
e. Knee-chest position → ↑ aortic wave reflection → ↑ pres on L side of heart thus ↓ R→L shunt
2. Total Surgical Repair
a. Infants 1 yr of age or younger
b. <5% peri-operative mortality
c. Relief of R outflow tract stenosis
d. Repair of VSD
e. Other reconstructive work as reqd
Prognosis
1. Untreated → progressive RVH and dilation – dilated cardiomyopathy progresses to RHF then LHF
a. Survival rates 75% after 1 yr of life, 60% by 4 yrs, 30% by 10 yrs, 5% by 40 yrs
2. Repaired TOF → potential to lead normal lives with excellent cardiac function
a. Ø lifetime correction – leaky pulmonary valve, continued R outflow stenosis, arrhythmias

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