lec4-sem5-CVSwk3-year3-20120505 (3)

7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)

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PATHOPHYSIOLOGY OF CONGENITAL HEART DISEASE

OBJECTIVES:

•

At the end of the lecture students will be able to• understand and describe the Pathophysiology of:

• Congenital heart defects

• Acyanotic heart diseases

• Cyanotic heart diseases

• Left to right shunts

• Right to left shunts

CONGENITAL HEART

DEFECTS

• Faulty embryogenesis (week 3-8)þ

• Usually MONO-morphic (i.e., SINGLE lesion) (ASD, VSD, hypo-

RV, hypo-LV)

• May not be evident until adult life (Coarctation, ASD)

• Overall incidence 1% of USA births

• INCREASED simple early detection via non invasive methods,

e.g., US, MRI, CT, etc.



Tricuspid atresia

1120Total anomalous pulmonary venous connection

1136Truncus arteriosus

4388Transposition of great arteries

4388Aortic stenosis

4396Atrioventricular septaldefect

5492Coarctation of aorta

5577Tetralogy of Fallot

7781Patentductus arteriosus

8836Pulmonary stenosis

101043Atrial septaldefect

424482Ventricular septaldefect

%Incidence per Million Live

BirthsMALFORMATION

GENETICS

• Gene abnormalities in only 10% of CHD

• Trisomies 21, 13, 15, 18, XO

• Mutations of genes which encode for transcription

factorsTBX5ASD,VSD

NKX2.5ASD

• Region of chromosome 22 important in heart development,22q11.2 deletionconotruncus, branchial arch, face

ENVIRONMENT

• RUBELLA

• TERATOGENS

CONGENITAL HEART DISEASE

• Congenital heart disease is often divided

• into two types:

• Cyanotic (blue discoloration caused by a relative lack of oxygen)

• non-cyanotic

• LR SHUNTS: all “D’s” in their names



• NO cyanosis

• Pulmonary hypertension

• SIGNIFICANT pulmonary hypertension is IRREVERSIBLE

• RL SHUNTS: all “T’s” in their names

• CYANOSIS (i,.e., “blue” babies)• VENOUS EMBOLI become SYSTEMIC

• OBSTRUCTIONS

LR

• ASD

• VSD

• ASVD

• PDA


• Non-cyanotic: (left to right shunt)

• Ventricular septal defect (VSD)

• Atrial septal defect (ASD)

• Patent ductus arteriosus (PDA)

• Aortic stenosis

•Pulmonic stenosis

• Coarctation of aorta

• Atrioventricular canal (endocardial cushion defect)

ASD

• NOT patent foramen ovale

• Usually asymptomatic until adulthood

• SECUNDUM (90%): Defective fossa ovalis

• PRIMUM (5%): Next to AV valves, mitral cleft• SINUS VENOSUS (5%): Next to SVC with anomalous pulmonary

veins draining to SVC or RA

• Sinus venosus defect: high in the septum.

• Ostium secundum defect: midseptum.



• Ostium primum defect: low in the septum.

• Pathophysiology: L-R shunt-increased flow across Rt heart-RV

& PA enlargement.

• Clinical features: asymptomatic, slow wt gain,

• Diagnosis: Rt ventricular heave, systolic murmur, fixed widesplit S2.

ATRIAL SEPTAL DEFECT

ATRIAL SEPTAL DEFECT

VSD

• By far, most common CHD defect

• Only 30% are isolated

• Often with TETRALOGY of FALLOT

• 90% involve the membranous septum

• If muscular septum is involved, likely to have multiple holes• SMALL ones often close spontaneously

• LARGE ones progress to pulmonary hypertension.



• VENTRICULAR SEPTAL DEFECT

• Most common CHD (26%),may be single or

• multiple

• Pathophysiology: Lt-Rt shunt as long as pulmonary vascular

resistance is lower than systemic resistance, if reverse shuntreverses

• Large defects lead to pul. hypertension-Eissenmenger

syndrome.

• Clinical features: depend on size, asymptomatic, growth failure,

recurrent LRTI, congestive heart failure,

• Diagnosis: pansystolic murmur,

• Asymptomatic if defect is small.

• Heart failure with dyspnea, frequent respiratory infections, and

poor growth if defect is large.

• Pansystolic murmur maximal at the left sternal border.



PDA

• 90% isolated

• HARSH, machinery-like murmur

• LR, possibly RL as pulmonary hypertension approaches

systemic pressure• Closing the defect may be life saving

• Keeping it open may be life saving (Prostaglandin E1). Why?

Ans: TGA, TA, TAPVC

• Connection between PA & descending aorta

• 10% of CHD

• Pathophysiology: Lt-Rt shunt, reverses if pulmonary resistance

increases-RV enlargement. If PDA is large Eissenmenger syndrome can develop

• Clinical features: depend on size & direction of flow, slowgrowth

• Diagnosis: bounding pulse, continous murmur, loud S2

• Murmur usually systolic, sometimes continuous, “machinery”

• Poor feeding, respiratory distress, and frequent respiratory

infections in infants with heart failure



• Physical exam and echocardiography

AVSD

•

Associated with defective, inadequate AV valves• Can be partial, or COMPLETE (ALL 4 CHAMBERS FREELY

COMMUNICATE)þ

• COMPLETE ATRIOVENTRICULAR CANAL



RL

• Tetralogy of Fallot

• Transposition of great arteries

• Truncus arteriosus

• Total anomalous pulmonary venous connection

• Tricuspid atresia




• Cyanotic: (right to left shunt)

• Tetralogy of Fallot

•Transposition of the great vessels

• Tricuspid atresia

• Total anomolous pulmonary venous return

• Truncus arteriosus

• Hypoplastic left heart

• Pulmonary atresia

• Some forms of total anomalous pulmonary venous return

• Ebstein’s anomaly

RL SHUNTS

• TETRALOGY of FALLOT most COMMON

• 1) VSD, large

• 2) OBSTRUCTION to RV flow

• 3) Aorta OVERRIDES the VSD

• 4) RVH

• SURVIVAL DEPENDS on SEVERITY of SUBPULMONIC

STENOSIS• Can be a “PINK” tetrology if pulmonic obstruction is small, but

the greater the obstruction, the greater is the RL shunt

TETRALOGY OF FALLOT

• Pulmonary stenosis

• VSD of the membranous portion

• Overriding aorta

• Right ventricular hypertrophy due to shunting of blood• Addition of an atrial septal defect falls in the category of

Pentalogy of Fallot.

• Hypoxic spells and squatting.



• Cyanosis and clubbing.

• Addition of an atrial septal defect falls in the category of

Pentalogy of Fallot.

• Hypoxic spells and squatting.

• Cyanosis and clubbing.

TGA (TRANSPOSITIONof GREAT ARTERIES)

• NEEDS a SHUNT for survival, obviously

• PDA or PFO (65%), “unstable” shunt

• VSD (35%), “stable” shunt



• RV>LV in thickness

• Fatal in first few months

• Surgical “switching”

• Aorta from right ventricle, pulmonary artery from left ventricle

• Cyanosis from birth, hypoxic spells sometimes present• Heart failure often present

• Cardiac enlargement and diminished pulmonary artery segment

on x-ray

• Anatomic communication must exist between pulmonary and

systemic circulation, VSD, ASD, or PDA.

• TRUNCUS ARTERIOSUS



• Single large vessel overrides the ventricular septum and

distributes all the blood ejected from the heart.

• Large VSD is present.

TRICUSPID ATRESIA

• Tricuspid valve is completely absent in about 2% of newborns

with congenital heart disease.

• Blood flows from right atrium to left atrium through foramen

ovale.

• Early cyanosis.

• Hypoplastic RV

• Needs a shunt,

• ASD, VSD, or PDA

• High mortality.



• Total Anomalous Pulmonary Venous Connection (TAPVC)

• PULMONARY VEINS do NOT go into LA, but into L. innominate

v. or coronary sinus

• Needs a PFO or a VSD

• HYPOPLASTIC LA

• Pulmonary veins do not make a direct connection with the left

atrium.

• Blood reaches the left atrium only through an atrial septal defect

or patent foramen ovale.

• Pulmonary congestion, tachypnea, cardiac failure, and variable

cyanosis.

OBSTRUCTIVE CHD

• COARCTATION of aorta

• Pulmonary stenosis/atresia

• Aortic stenosis/atresia



PULMONARY STENOSIS

• No symptoms in mild or moderately severe lesions.

• Cyanosis and right-sided heart failure in patients with severe

lesions.

• High pitched systolic ejection murmur maximal in second left

interspace.• Ejection click often present.



COARCTATION OF AORTA

• M>F

• But XO’s frequently have it• INFANTILE FORM (proximal to PDA) (SERIOUS)

• ADULT FORM (CLOSED DUCTUS, i.e., NO PDA)

• Bicuspid aortic valve 50% of the time

AORTIC STENOSIS/ATRESIA

• VALVULAR

• If severe, hypoplastic LVfatal

• SUB-valvular (subaortic)þ

•

Aortic wall THICK BELOW cusps• SUPRA-valvular

• Aortic wall THICK ABOVE cusps in

ascending aorta

• Asymmetric Septal Hypertrophy

(Idiopathic

Hypertrophic Subaortic Stenosis)

lec4-sem5-CVSwk3-year3-20120505 (3)

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