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 PDA ASD Coarc TGA ToF PS 10 - AS 7 - Truncus TA Others

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

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 LAR SEPTAL 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

Management 1) 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 ( 3 rd ~4 th 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-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. P 2 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-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 S 2 sounds single and weak, but may be loud reflecting A 2 ◆ Systolic ejective murmur at middle left/upper sternal border ◆ Central cyanosis with finger/toe clubing

T O F 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 PCO 2 ◆ 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 Classification Anatomy Valvular stenosis without dysplasia (dome- shape) Dysplasia of pulmonary valve, frequently associated with small annulus Severety pressure gradient Mild < 40 mmHg Moderate 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 2 nd LICS Ejective sound( early systolic click )

Bernoulli principle & pressure gradient estimation ⊿ P = 4(V 2 2 —V 1 2 ) ≈ 4 V 2

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