patoloji-ders-notlari

Title

Serdar Balcı

Congenital Heart Diseases

Serdar BALCI, MD

Congenital heart diseases

Abnormalities of the heart or great vessels that are present at birth

20-30% of all birth defects

6-8 of every 1000 liveborn infants

Incidence is higher in premature infants and in stillborns

Robbins Basic Pathology

Surgery

May correct the hemodynamic abnormalities

Repaired heart may not be completely normal

Myocardial hypertrophy and cardiac remodeling may be irreversible

All cardiac surgery results in some degree of myocardial scarring

Secondary arrhythmias, ischemia, and myocardial dysfunction, appear many years after surgical correction

Pathogenesis

• Faulty embryogenesis during gestational 3-8 weeks
• Cause is unknown in almost 90% of cases
• Environmental causes
  • Congenital rubella infection
  • Teratogens
  • Maternal diabetes
  • Genetic factors are the best characterized
    • Familial forms of congenital heart disease
    • Trisomies 13, 15, 18, and 21, and Turner syndrome

Cardiac morphogenesis

• Multiple genes
  • Commitment of progenitor cells to the myocardial lineage
  • Formation and looping of the heart tube
  • Segmentation and growth of the cardiac chambers
  • Cardiac valve formation
  • Connection of the great vessels to the heart
  • Mechanical force imparted by flowing pulsatile blood
• Multiple genes
  • Wnt
  • Vascular endothelial growth factor
  • Bone morphogenetic protein
  • Transforming growth factor-β
  • Fibroblast growth factor
  • Notch pathways

Robbins Basic Pathology

Shunt

abnormal communication between chambers or blood vessels

Abnormal channels permit blood flow down pressure gradients from the left (systemic) side to the right (pulmonary) side of the circulation or vice versa

*Malformations causing a ** *left-to-right shunt

*Malformations causing a ** *right-to-left shunt

*Malformations causing an ** *obstruction

Left-to-right shunts

Most common type of congenital cardiac malformation

Atrial septal defects

Ventricular septal defects

Patent ductus arteriosus

Cyanosis is not an early feature

Left-to-right shunting with volume and pressure overloads eventually causes pulmonary hypertension

Secondarily right-sided pressures that exceed those on the left

Reversal of blood flow occurs, right-to-left shunting, cyanosis

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*In contrast, ** *left-to-right shunts __ (e.g., ASD, VSD, and patent ductus arteriosus [PDA]) increase pulmonary blood flow, but are not __ initially __ associated with cyanosis. However, left-to-right shunts chronically elevate both volume and pressure in the normally low-pressure, low-resistance pulmonary circulation. To maintain relatively normal distal pulmonary capillary and venous pressures, the muscular pulmonary arteries (<1 mm in diameter) initially respond by undergoing medial hypertrophy and vasoconstriction. However, prolonged pulmonary arterial vasoconstriction stimulates the development of irreversible obstructive intimal lesions analogous to the arteriolar changes seen in systemic hypertension; pulmonary arteries can even develop frank atherosclerotic lesions (__ Chapter 11 *). The right ventricle also responds to the pulmonary vascular changes by undergoing progressive right ventricular hypertrophy. Eventually, pulmonary vascular resistance approaches systemic levels, and the original left-to-right shunt becomes a right-to-left shunt that introduces poorly oxygenated blood into the systemic circulation ** *(Eisenmenger syndrome).

Left-to-right shunts

• Reversal of flow and shunting of unoxygenated blood into the systemic circulation
  • Eisenmenger syndrome
• Significant pulmonary hypertension develops
  • The structural defects of congenital heart disease are considered irreversible

Patent Foramen Ovale

• Septum primum and septum secundum grow to occlude the foramen ovale
• 80% after growth fusion of septa
• 20% of cases, a patent foramen ovale
  • Potentially allow transient right-to-left blood flow
  • Paradoxical embolism

Atrial Septal Defect

Abnormal fixed opening in the atrial septum

Unrestricted blood flow between the atrial chambers

Robbins Basic Pathology

Ostium secundum ASDs

90% of ASDs

Smooth-walled defects near the foramen ovale

Without other associated cardiac abnormalities

Right atrial and ventricular dilation, right ventricular hypertrophy, and dilation of the pulmonary artery

Robbins Basic Pathology

Ostium primum ASDs

5%

Lowest part of the atrial septum

Associated with mitral and tricuspid valve abnormalities

Additional defects may include a VSD and a common atrioventricular canal

Robbins Basic Pathology

Sinus venosus ASDs

5%

High in the atrial septum

Anomalous drainage of the pulmonary veins into the right atrium or superior vena cava

Robbins Basic Pathology

Ventricular Septal Defects

Most common congenital cardiac anomaly at birth

Basal (membranous) region is the last part of the septum to develop and is the site of approximately 90% of VSDs

Most VSDs close spontaneously in childhood

20-30% occur in isolation

Most associated with other cardiac malformations

Robbins Basic Pathology

**Ventricular septal defect of the membranous type **

Robbins Basic Pathology

Minute defects in the membranous septum to large defects involving virtually the entire interventricular wall

Right ventricle is hypertrophied and often dilated

Diameter of the pulmonary artery is increased

Vascular changes typical of pulmonary hypertension

Robbins Basic Pathology

• Small defects close spontaneously
• Small defects
  • Jet flow → damage endocardium → prone to infective endocarditis
• Larger defect
  • Pulmonary hypertension → heart failure

Robbins Basic Pathology

Patent Ductus Arteriosus

• 90% are isolated
• Can be life saving in combined anomalies
• Close and form ligamentum arteriosum
  • Arterial oxygenation
  • Decreased pulmonary vascular resistance
  • Declining local levels of prostaglandin E2

Robbins Basic Pathology

• Reversal of flow and shunting of unoxygenated blood into the systemic circulation
  • Eisenmenger syndrome

Robbins Basic Pathology

Right-to-Left Shunts

• Severe, systemic, early cyanosis
• Clubbing of the tips of the fingers and toes
  • Hypertrophic osteoarthropathy
• Polycythemia
• **Paradoxical embolization **
• Tetralogy of Fallot
• Transposition of the great vessels

Tetralogy of Fallot

Most common cause of cyanotic congenital heart disease

5% of all congenital cardiac malformations

Robbins Basic Pathology

Anterosuperior displacement of the infundibular septum

Abnormal septation between the pulmonary trunk and the aortic root

Robbins Basic Pathology

• VSD
• Right ventricular outflow tract obstruction
  • Subpulmonic stenosis
• Overriding of the VSD by the aorta
• Right ventricular hypertrophy

Robbins Basic Pathology

• **The heart is large and “boot-shaped” **
  • Right ventricular hypertrophy
• Proximal aorta is dilated
• Pulmonary trunk is hypoplastic
• Left-sided cardiac chambers are of normal size
• Right ventricular wall is markedly hypertrophied

Robbins Basic Pathology

• VSD usually is large
• Aortic valve lies immediately over the VSD
  • Overriding aorta
  • Flow from both ventricles

Robbins Basic Pathology

• Obstruction of the right ventricular outflow
  • Narrowing of the infundibulum
  • Subpulmonic stenosis
  • Pulmonary valve stenosis
  • Complete atresia of the valve
  • Proximal pulmonary arteries
  • Persistent PDA
  • Dilated bronchial arteries

Robbins Basic Pathology

Transposition of the Great Arteries

Separation of the systemic and pulmonary circulations

Aorta from the right ventricle and the pulmonary artery from the left ventricle

Abnormal formation of the truncal and aortopulmonary septa

Atrium-to-ventricle connections are normal (concordant)

Shunt is necessary for life

**Transposition of the great arteries **

Robbins Basic Pathology

Transposition of the Great Arteries with VSD

• 1/3 of cases
• Provide stable shunts
• Marked right ventricular hypertrophy
  • Functions as the systemic ventricle
• Left ventricle is atrophic

Robbins Basic Pathology

Patent foramen ovale

PDA

They tend to close

Emergent surgical intervention within the first few days of life

Robbins Basic Pathology

Obstructive Lesions

• At the level of the heart valves
• More distally within a great vessel
• Proximal to the valve
  • Subpulmonic stenosis in tetralogy of Fallot
• Pulmonic valve stenosis
• Aortic valve stenosis
• Aortic valve atresia
• Coarctation of the aorta

Aortic Coarctation

Robbins Basic Pathology

Coarctation (narrowing, or constriction)

Common form of obstructive congenital heart disease

Males are affected twice as often as females

Females with Turner syndrome frequently have coarctation

Can occur as a solitary defect

More than half of the cases accompanied by a bicuspid aortic valve

**Aortic valve stenosis, ASD, VSD, or mitral regurgitation also can be present **

Coarctation of AortaInfantile form

• Hypoplasia of the aortic arch proximal to a PDA
• Circumferential narrowing of the aortic segment between the left subclavian artery and the ductus arteriosus
• Ductus typically is patent and is the main source of (unoxygenated) blood delivered to the distal aorta
• Pulmonary trunk is dilated to accommodate the increased blood flow
• Right side of the heart now perfuses the body distal to the narrowed segment
  • Right ventricle typically hypertrophied

Robbins Basic Pathology

Coarctation of AortaAdult form

**More common **

Postductal coarctation

Aorta is sharply constricted by a tissue ridge adjacent to the nonpatent ligamentum arteriosum

Constricted segment is made up of smooth muscle and elastic fibers that are continuous with the aortic media

Proximal to the coarctation, the aortic arch and its branch vessels are dilated and the left ventricle is hypertrophied

Robbins Basic Pathology

Robbins Basic Pathology

Autopsy Pathology: A Manual and Atlas

Autopsy Pathology: A Manual and Atlas

Autopsy Pathology: A Manual and Atlas

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Autopsy Pathology: A Manual and Atlas

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Autopsy Pathology: A Manual and Atlas

Autopsy Pathology: A Manual and Atlas

Autopsy Pathology: A Manual and Atlas

Autopsy Pathology: A Manual and Atlas

Autopsy Pathology: A Manual and Atlas

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