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Congenital Heart Disease

CSBR.Prasad, MD.,

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Congenital Heart Disease - CHD• CHD is a general term designating abnormalities of the heart or great

vessels that are present at birth• CHD arises from faulty embryogenesis during 3-8 weeks of gestation• Incidence - 5%

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Twelve disorders account for about 85% of cases

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Congenital Heart Disease – Cardiac Development• The fetal heart consists of a single chamber until the fifth week of

gestation• Then, it is divided by the development of interatrial and

interventricular septa and by the formation of atrioventricular valves from endocardial cushions

• A muscular interventricular septum grows upward from the apex toward the base of the heart. It is joined by the down-growing membranous septum, thereby separating right and left ventricles

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CHD - Cardiac DevelopmentDay 15: Multipotent progenitor cells originate in lateral mesoderm and migrate to the midline

Day 20: beating tube Day 28:

Migration of neural crest cells, out flow tract & aortic arch formation

Endocardial cushion formationDay 50: Formation of four chambered heart

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CHD - Cardiac Development• This well orchestrated event involves many genes, transcription

factors, signaling pathways• Each heart field is differentially marked by the expression of distinct

set of genes• 1st heart field: Hand1

• (most of the left ventricle derived from this field)• 2nd heart field: Hand2 and FGF-10

• (Out flow tract, right ventricle and atria are derived from this field)

• Pathways involved: Wnt, Hedghog, Notch-Delta• Growth factors involved: VEGF, TGF-beta, FGF• Specific micro-RNAs• Others: Hemodynamic forces in the developing heart

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CHD - Cardiac Development

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CATCH-22Down’s syndromeTrisomies (13,18, 21)

Most common genetic cause of congenital heart disease is

Trisomy 21 (Down’s Syndrome)

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Congenital Heart Disease – Environmental factors

• Mutations in Csx/Mkx2-5• Down syndrome (trisomy 21) and other trisomies• Turner syndrome and • Di George syndrome• Intrauterine influences

• Rubella• Alcohol• Phenytoin• Amphetamines• Lithium• Estrogenic steroids and, • Thalidomide (historical)• Maternal diabetes

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Congenital Heart Disease - gist• CHD is a consequence of faulty embryonic

development• Either as misplaced structures OR

• Eg: transposition of the great vessels) or • As an arrest in the progression of a normal structure (from an early stage to one that is more mature)

• Eg: ASD

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Congenital Heart Disease – Clinical featuresCHDs can be organized into three major categories:

1. Malformations causing a left-to-right shunt2. Malformations causing a right-to-left shunt3. Malformations causing an obstruction

Definition:SHUNT: is an abnormal communication between chambers or blood vessels.

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1-Malformations causing a left-to-right shunt• Not initially associated with cyanosis• However, over the course of years, the patient may

develop right to left shunt – EISENMENGER syndrome

Left to right shunt results in pulmonary hypertension and associated changes in the pulmonary circulation. After the development of PHT the structural defects in

CHDs are considered irreparable.JAN-2015-CSBRP

Common congenital left-to-

right shunts

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2-Malformations causing a right-to-left shunt• Associated with cyanosis• Paradoxical embolism• Hypertrophic osteoarthropathy• Polycythemia

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Congenital Heart Disease – Clinical features -Hypertrophic osteoarthropathy

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1. Tetralogy of Fallot2. Transposition of the great

arteries3. Persistent truncus arteriosus4. Tricuspid atresia, and 5. Total anomalous pulmonary

venous connection

Common congenital right-to-left shunts


3-Malformations causing an obstruction• Abnormal narrowing of chambers, valves or blood vessels• Complete obstruction is called Atresia

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Aortic coarctation

with and without PDA

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Atrial Septal Defect - ASD• Abnormal fixed opening in the atrial septum caused by incomplete

tissue formation• Atria communicate with each other• Cf: Patent foramen ovale – PFO

• Failure to close foramen that is a part of normal development

• Both ASD & PFO result from defects in the formation of interatrial septum

• Usually asymptomatic until adulthood• Common genetic variation near a gene MSX1 is strongly associated

with the risk of an ASDJAN-2015-CSBRP

Atrial Septal Defect Development of interatrial septum• Septum primum - originates posteriorly

• Ostium primum• During fetal development, this opening allows blood to be shunted from the right atrium

to the left• Ostium secundum

• The ostium secundum allows continued shunting of blood from the right atrium to the left

• Septum secundum - originates anteriorly• Foramen ovale

• The foramen ovale is continuous with the ostium secundum, again providing for continued shunting of blood

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Atrial Septal Defect Development of interatrial septum

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Atrial Septal Defect

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Atrial Septal Defect ClassificationAccording to their location:• Secundum ASD:

• 90% of all ASDs• Deficient septum secundum• No other associated anomalies• May be of any size, may be fenestrated

• Primum anomalies• 5% of ASDs• AV valve abnormalities

• Sinus venosus defects• 5% of ASDs• Located near the entrance of SVC• Associated with anomalous venous return to RAJAN-2015-CSBRP

Atrial Septal Defect • The most common type of ASD: The ostium secundum type,

comprises 6–10% of all congenital heart diseases• Mechanisms:

• Enlarged foramen ovale• Inadequate growth of the septum secundum, or • Excessive absorption of the septum primum

• 10-20% of individuals may have MVP• Lutembacher's syndrome: Ostium secundum ASD + acquired MS

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Patent Foramen Ovale• FO closes permanently in 80% of people by 2 years of age• In the remaining 20%, the unsealed flap can open if right-sided

pressures become elevated• Pulmonary hypertension or even transient increases in right-sided

pressures can produce brief periods of right-to-left shunting, with the possibility of paradoxical embolism

• During a bowel movement• coughing or• Sneezing

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Patent Ductus Arteriosus - PDA Ductus Arteriosus

• The ductus arteriosus (DA) arises from the PA and joins the aorta • During intrauterine life, DA shunts blood from the PA to the aorta• Shortly after birth DA constricts and is closed after 1 to 2 days

• This occurs in response to:• Increased arterial oxygenation• Decreased pulmonary vascular resistance and • Reduced levels of PGE2 locally

• After a few months - ligamentum arteriosum

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Patent Ductus Arteriosus - PDA Ductus Arteriosus

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Ductus ArteriosusLigamentum arteriosum

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Patent Ductus Arteriosus - PDA• Constitute 7% of cases of CHDs (and 90% of them are isolated)• Maternal Rubella infection• PDA produces a characteristic continuous harsh “machinery-like”

murmur• Complications: PHT, IE• Isolated PDA should be closed as early in life as is feasible• Preservation of ductal patency may be necessary in some CHDs

• Eg: Aortic valve atresia

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Ventricular Septal Defect - VSDVentricular septal defects occur as:1. A small hole in the membranous septum2. A large defect involving more than the membranous region

(perimembranous defects)3. Multiple defects in the muscular portion, which are more common

anteriorly but can occur anywhere in the muscular septum or 4. Complete absence of the muscular septum (leaving a single ventricle)NOTE: A small septal defect may have little functional significance and may actually close spontaneously as the child matures

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VSD

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VSD• VSDs are classified according to their size and location

1. Membranous VSD2. Infundibular VSD

• Membranous VSD: Single• Infundubular VSD: Multiple, small• 70-80% are associated with other CHD• 20-30% occur in isolation

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VSD• Large VSDs

• cause PHT / RVH• Shunt reversal, cyanosis and death

• Small VSDs• Present much later in life• 50% may close spontaneously

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VSD (membranous type)

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VSD (Infundibular type)

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TETRALOGY OF FALLOT:• DOMINANT RIGHT-TO-LEFT SHUNT• IT IS THE MOST COMMON CYANOTIC CHD • Four cardinal features are:

1. VSD2. Obstruction to right ventricular out flow i.e. PS3. Over riding of aorta4. Right ventricular hypertrophy (RVH)

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TETRALOGY OF FALLOT:• Heart is usually enlarged – boot shaped• Due to marked right ventricular hypertrophy

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Persistent Truncus Arteriosus• A common trunk for the origin of the aorta, pulmonary arteries• Results from absent / incomplete partitioning of the truncus

arteriosus by the spiral septum• Truncus overrides the VSD and receives blood from both the

ventricles• Clinical Features:

• Recurrent pulmonary infections• Cyanosis• PCV / clubbing of fingers• PHT / heart failure / early death

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Truncus Arteriosus

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Transposition of the Great Arteries - TGA• Ventriculoarterial discordance: The aorta arises from the

right ventricle, while the pulmonary artery emanates from the left ventricle

• Concordant AV connections: RA joining the RV and the LA emptying into the LV

• Embryology: TGA results from abnormal formation of the truncal and aortopulmonary septa

• Result: Separation of pulmonary and systemic circulation• A condition incompatible with postnatal life unless a shunt exists

for adequate mixing of bloodJAN-2015-CSBRP

Transposition of the Great Arteries - TGA

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Transposition of the Great Arteries - TGA• The outlook for infants with TGA depends on the

degree of blood “mixing”• Patients with TGA and a VSD often have a stable shunt• Patients with TGA and ASD / PDA have unstable shunt as

they many close early in life• RVH• Left ventricle may become thin walled

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Coarctation of the Aorta • F:M = 1:2• Females with Turner syndrome are also frequently affected• There are two classic forms:

• Infantile form (symptomatic in early childhood)• Adult form (with a ridge like infolding of the aorta)

• 50% of cases accompanied by a bicuspid aortic valve• Patients may have berry aneurysms

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Coarctation of the AortaPathogenesis

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Coarctation of the Aorta • Clinical manifestations depend on:

• Severity of the narrowing and • Patency of the ductus arteriosus

• Coarctation of the aorta with a PDA: Cyanosis localized to the lower half of the body

• Coarctation of the aorta without PDA: Unless the aortic constriction is severe most children are asymptomatic

• Typically there is hypertension in the upper extremities with weak pulses and hypotension in the lower extremities

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Coarctation of the Aorta• Development of collateral circulation:

• Intercostal and • Internal mammary arteries

• X-ray - “notching” of the undersurfaces of the ribs

• Pan systolic murmurs / thrill• Concentric LVH• Treatment:

• Surgical resection and end-to-end anastomosis or • Replacement of the affected aortic segment by a prosthetic graft

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Coarctation of the AortaCollaterals, Notched ribs

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Coarctation of the Aorta

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CHDs - Gist• Congenital heart disease represents defects of cardiac chambers or the great

vessels• These either result in shunting of blood between the right and left circulation or

cause out flow obstructions• Lesions range from relatively asymptomatic to rapidly fatal• Both Environmental (toxic or infectious) and genetic factors contribute• Left-to-right shunts are most common and are typically associated with ASDs,

VSDs, or a PDA• Right-to-left shunts are most commonly caused by TOF or TGA• Obstructive lesions include aortic coarctation

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