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Heart Defects

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Heart Defects - 1

• Heart and vascular abnormalities make up the largest category of human birth defects.

• Genetic factors• Environmental agents• Both (multifactorial causes)• Cardiovascular teratogens include rubella

virus and thalidomide. Others include retinoic acid (Accutane), alcohol.

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Heart Defects - 2

• Atrial Septal Defect• Tricuspid atresia• Ebstein anomaly• Ventricular septal defects (VSDs)• Persistent truncus arteriosus • Transposition of the great vessels

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Atrial septal defect (ASD)

• A congenital heart abnormality with an incidence of 6.4/10,000 births.

• 2:1 prevalence in female to male infants.• Most significant defects is the:• Ostium secundum defect.• Persistent atrioventricular canal

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• A. Normal atrial septum formation.• B,C. Ostium secundum defect caused by excessive resorption of the septum

primum. • D,E. Similar defect caused by failure of development of the septum secundum. • F. Common atrium, or cor triloculare biventriculare, resulting from complete failure

of the septum primum and septum secundum to form.

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Persistent atrioventricular canal

• Endocardial cushions : Structures consisting of loose connective tissue covered by endothelium that are responsible for most septation processes occurring in the heart.

• Divide the canal into a right and left orifice.• Participate in formation of the membranous

portion of the interventricular septum and in closure of the ostium primum.

• Persistent atrioventricular canal happens when Endocardial cushions fail to fuse.

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• A. Persistent common atrioventricular canal. This abnormality is always accompanied by a septum defect in the atrial as well as in the ventricular portion of the cardiac partitions.

• B. Valves in the atrioventricular orifices under normal conditions.

• C. Split valves in a persistent atrioventricular canal.

• D,E. Ostium primum defect caused by incomplete fusion of the atrioventricular endocardial cushions.

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Tricuspid atresia

• Obliteration of the right atrioventricular orifice.• characterized by the absence or fusion of the

tricuspid valves.• Always associated with• (a) patency of the oval foramen• (b) ventricular septal defect• (c) underdevelopment of the right ventricle• (d) hypertrophy of the left ventricle.

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• A. Normal heart.

• B. Tricuspid atresia. Note the small right ventricle and the large left ventricle.

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Ventricular septal defects (VSDs)

• Involves the membranous or muscular portion of the septum.

• Most common congenital cardiac malformation (12/10,000 births)

• Often associated with abnormalities in partitioning of the conotruncal region

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• A. Normal heart.• B. Isolated defect in the membranous portion of

the interventricular septum. Blood from the left ventricle flows to the right through the interventricular foramen (arrows).

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Tetralogy of Fallot

• Most frequently occurring abnormality of the conotruncal region.

• Due to an unequal division of the conus resulting from anterior displacement of the conotruncal septum

• produces four cardiovascular alterations:• (a) pulmonary infundibular stenosis• (b) a large defect of the interventricular septum;• (c) an overriding aorta that arises directly above the septal

defect• (d) hypertrophy of the right ventricular wall because of

higher pressure on the right side.

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• A. Surface view. • B. The four components of the defect: pulmonary

stenosis, overriding aorta, interventricular septal defect, and hypertrophy of the right ventricle.

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Persistent truncus arteriosus

• Results when the conotruncal ridges fail to fuse and to descend toward the ventricles

• Occurs in 0.8/10,000 births

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• The pulmonary artery originates from a common truncus (A).

• The septum in the truncus and conus has failed to form (B).

• This abnormality is always accompanied by an interventricular septal defect.

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Transposition of the great vessels

• Occurs when the conotruncal septum fails to follow its normal spiral course and runs straight down.

• As a consequence, the aorta originates from the right ventricle, and the pulmonary artery originates from the left ventricle.

• Occurs in 4.8/10,000 births• Sometimes is associated with a defect in the

membranous part of the interventricular septum.

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• A. Transposition of the great vessels. • B. Pulmonary valvular atresia with a normal aortic

root. The only access route to the lungs is by way of a patent ductus arteriosus.

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• A. Aortic valvular stenosis. • B. Aortic valvular atresia. Arrow in the arch of the

aorta indicates direction of blood flow. The coronary arteries are supplied by this retroflux. Note the small left ventricle and the large right ventricle.

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Valvular stenosis

• Valvular stenosis of Pulmonary artery or aorta occurs when the semilunar valves are fused for a variable distance.

• Similair incidence for both, occurs in 3 to 4/10,000 births.

• Valvular stenosis of the pulmonary artery: the trunk of the pulmonary artery is narrow or even atretic.

• Aortic valvular stenosis

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Some other defects

• DiGeorge sequence: characterized by a pattern of malformations that have their origin in abnormal neural crest development.

• Ectopia cordis: a rare anomaly in which the heart lies on the surface of the chest.

• Ebstein anomaly: a condition where the tricuspid valve is displaced toward the apex of the right ventricle.