CONGENITAL HEART DISEASE

IN CHILDHOOD

Definition

Cardiovascular malformation(s) resulted from deficient or interrupted development of heart embryo, or delayed degeneration of a cardiac structure after birth.

Basic deformities consisting CHDs are:• abnormal communication• obstruction to flow• abnormal connection between cardiac segments• combination of the above

Incidence

• 7~8/1000 live births

• 150,000 new born cases of CHD

each year in China

• 20-30% CHD cases die before

their first birthday

Relative prevalence of specific CHDs (%)

Canada(15104 live births) China( 2659 autopsies )

VSD 28 24.6 PDA 10 6.7 ASD 10 13.5 Coarc. 5 6.9 TGA 5 6.7 ToF 10 5.2 PS 10 - AS 7 - Truncus 0.7 3.3 TA 1.2 - Others 13.1 33.1 

Etiology Clear-cut genetic 8% • 5% chromosomal e.g 21-trisomy

Turner’s(XO) • 3% single gene e.g Marfan’s (AD)

Hunter’s (XR)

Definitely environmental 2% e.g Rubella / PDA

In most instance, however, CHDs are results of interaction of genetic predisposition and environmental insults during early gestation( 4-8weeks ).

Shift of threshold The threshold of CHD due to environmental without environmental factors factors

A B C A: Families without CHD susceptibility B: Families with moderate CHD susceptibility C: Families with severe CHD susceptibility 

The hypothesis on the etiology of CHD ( by Nora JJ,1968 )

New horizon

• Recent genetic research has led to a viewpoint: “inherited CHDs” seem much more frequent than previously thought

• Single gene defect or gene allele microdeletion (such as 22q11 ) often cause CHD

Clinical classification     Non-cyanotic group

◆ L→R shunts ‘potentially cyanotic’ e.g. ASD,VSD,PDA. ◆ No shunt obstruction/stenosis, e.g. AS, PS, Coarc. Cyanotic group ◆ R→L shunts, may be a wrong connection of segments e.g. TGA, ToF

Diagnostic approaches and tools

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心 脏特殊检查

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Doppler

CHDs

Observ /Hct Acyanotic Cyanotic

X-ray PBF→ PBF↑ PBF↓ PBF↑

ECG RVH LVH RVH LVH RVH LVH RVH LVH

or CVH or CVH

PS AS ASD VSD ToF TA TGA TGA/PS

PDA TAPVR Truncus

UVH

VENTRICU LARSEPTAL DEFECT

Pathology

◆ Perimembranous (membranous)

80%

◆ Subpulmonic (supracristal)

5~7%

◆ Muscular

the rest

Size of VSDs

Large Moderate Small

VSD diameter(mm) ＞ 5 3~5 ＜ 3

VSD area/ aorta area 1/2~1 1/2 ¼

◆ When VSD area approaches that of aorta, it is refered to as ‘unrestrictive VSD’

Pathophysiology( hemodynamics )

Vena RA RV PA

cava

pulmonary

blood flow

LA LV Ao

Clinical manifestation

1) Small VSD symptom-free

2) Moderate to large VSD ： dependent on the shunt size

◆ Exercise intolerance CHF

◆ Repeated pulmonary infections

◆ (Cyanosis)

◆ (Delayed growth)

  Physical Examination

◆ loud P2 sound

◆ pansystolic harsh murmur at left sternal border, 3~5/6 grade / thrill

◆ mid-diagnostic murmur at apex

X-ray

Natural history and complications

◆ Spontaneous closure in at least 1/4~1/3 cases

  

◆ Infundibular stenosis may develop in 5~15%   

◆ A small portion will develop aortic insufficiency 

 

◆ In large VSD, pulmonary vascular obstructive pathology

may develop leading to reversed shunt----Eisengmenger’s syndrome

◆ Infectious endocarditis

Management1)  Medical

◆ Control of CHF with digitalis, diuretics and vasodilators in early infancy◆ Treatment of pulmonary infections◆ Prophylaxis against infectious endocarditis

2)  Surgical

◆ Indication---- Qp/Qs≥1.3:1. If there is significant pulmonary hypertension, the repair should be performed by 12~18months◆ Contraindication------ Eisenmenger’s syndrome

3) Transcatheter intervention

Developed for just a couple of years but quickly become popular and tends to substitute a part of surgery

Interventional procedure for VSD

Atrial Septal Defect

Classification and pathogenesis

◆ Secondum type ASD II

◆ Primum type ASD I

also: as a component of

endocardial cushing defect/

atrioventricular septal defect

Pathophysiology( hemodynamics )

Vena RA RV PA

cava

pulmonary

blood flow

LA LV Ao

Clinical manifestations

◆ Usually asymptomatic in childhood

◆ Increased susceptibility to respiratory infections and some degree of exercise intolerance may occur in large shunts

◆ Pulmonary vascular obstruction, congestive heart failure and arrhythmias( flatter/fibrillation ) likely to develop in adult life ( 3rd ~4th decade ).

Late complications of ASD• Decreased left ventricle distensibility

augments L-R shunt pulmonary hypertension

• RA dilatation atrial arrhythmias

• Symptomatic CHF which can be precipitated by the arrhythmia

Physical examination

◆ Widely split and fixed P2

◆ Grade 2~3/6 ejective systolic murmur

at upper left sternal border.

◆ Mid-diastolic rumble at lower left sternal

border, when the shunt is large.

ASD X-RayASD X-Ray

Management

      

◆ Elective surgical repair at age 4~5years

◆ Transcatheter occlusion of the defect with

artificial device has been widely accepted

to substitute surgery in the majority of cases

◆ Chemoprophylaxis against IE is not

indicated

Interventional procedure for ASD

Patent Ductus Ateriousus

Pathophysiology( hemodynamics )

Vena RA RV PA

cava

pulmonary

blood flow

LA LV Ao

Clinical manifestations

  ◆   Small ductus ----- asymptomatic.

◆ Large ductus ----- Similar to Large VSD

including the development of

pulmonary vascular obstruction pathology

when the ‘differential cyanosis’ may be

seen.

Physical examination ◆ A machinery-like continuous murmur at upper

left sternal border. P2 is usually loud but may

be obscured by the murmur.

◆ Mid-diastolic rumble at apex, when the shunt is

large.

◆ Peripheral vascular signs ---- bounding pulse /

pistol sound/capillary pulsation --- associated

with wide pulse pressure.

PDA X-RayPDA X-Ray

Management

1) Medical

◆ Care for medical complications similar to VSD

(CHF/pneumonia/IE prophylaxis,etc)

◆ Closure of PDA in premature neonates can be

precipitated by fluid restriction / Indomethacin

2) Surgical ligation

◆ Elective, anytime after 6 month except

intractable CHF

3) Transcatheter occlusion

◆ Has recently become the management of choice

Tetralogy of Fallot

Pathophysiology( hemodynamics )

Vena RA RV PA

cava

pulmonary

blood flow

LA LV Ao

Pathophysiological implication

◆ Pressures of both ventricles are balanced by a large VSD, RV pressure never exceeds systemic level, so that cardiomegaly / CHF rarely develop

    ◆ The more stenotic the RV outflow, the more severe the cyanosis. Therefore the two ends of the spectrum: mild PS---- ‘pink’ tetrology vs. most severe PS---- pulmonary atresia with VSD

◆ The PS is relatively fixed, hence the size of R→L is inversely correlated to SVR.

Clinical manifestations

◆ Cyanosis typically develops in 3~6 months of age

◆ Mostly symptomatic with dyspnea on exertion and delayed growth may exist

◆ Hypoxemic spells in infancy characterized by

◆ Squatting, usually appears when the patient begins to walk

◆ Brain abscess / thrombosis and tendency of

bleeding which may relate to rheological disorder

paroxysms of hyperpnea, increasing cyanosis, attenuation

of the murmur and may lead to convulsion or even death.

Physical examination ◆ Weak pulmonic component makes S2 sounds

single and weak, but may be loud reflecting A2

◆ Systolic ejective murmur at middle left/upper

sternal border

◆ Central cyanosis with finger/toe clubing

TTOOF X-RayF X-Ray

Management

1) Medical ◆ Antibiotic prophylaxis against endocarditis ◆ Maintain rheological condition at favorable state ◆ Detect and treat hypoxemic spell

2) Surgical ◆ Palliative procedures such as Blalock- Taussig’s for severe cases < 6 month or cases with PA hypoplasia. ◆ Corrective procedure ----- selective, any time after 1.5~2 year of age. However, more centers now prefer early corrective surgery even before 6 month of age.

Treatment of hypoximic spell

    RV outlet spasm?

SVR R to L

venus return shunt

◆   Knee-chest position respiratory blood pH

◆ O2 stimulation PCO2

     ◆ Morphine 0.1~0.2mg/kg, im;

      ◆ NaHCO3 1mEq/kg, iv;

      ◆ Vasoconstrictors such as phenylephrine 0.02mg/kg, iv;

◆ Propranolol, especially oral administration for long term

control

Pulmonary Stenosis

Definition

• supravalvular

• valvular

• Subvalvular

Further ClassificationAnatomy• Valvular stenosis without dysplasia (dome-

shape)• Dysplasia of pulmonary valve, frequently

associated with small annulus

Severety pressure gradient• Mild < 40 mmHg• Moderate 41-79 mmHg• Severe > 80 mmHg

Hemodynamics

Pressure overload of RV

RV hypertrophy RA enlargement/pressure

Right heart failure RA LA shunt

Clinical manifestation

• Symptom free in mild to moderate cases, even in severe cases

• Symptoms may include dyspnea and fatigue on effort, in severe cases there may be chest pain, syncope and occasionally sudden death during exercise

• In critical stenosis in infancy, CHF and cyanosis may occur

Physical Examination

• P2 split but usually weak

• Ejective systolic murmur grade 3-5 at 2nd LICS

• Ejective sound( early systolic click )

Bernoulli principle &

pressure gradient

estimation

⊿ P = 4(V22—V1

2) ≈ 4 V2

Treatment Indications for surgery• Symptomatic patients or asymptomatic severe cases • No treatment for mild cases, follow up for asymptomatic moderate patients • Balloon dilatation failed cases, especially with valve and annulus dysplasia

Indication for balloon valvuloplasty

• Pressure gradient >30mmHg• Dome- shaped valve is better indicated than dysplastic valve