نقص‌های مادرزادی قلبی

Congenital Cardiovascular Anomalies

• Congenital cardiovascular anomalies (CHDs) are abnormalities in the heart structure present at birth.
• A specialist in this field is a pediatric interventional cardiologist.
• Dr. Babazadeh, a pediatric interventional cardiologist at Babol Medical University, specialises in CHDs.

Classification of CHDs

• Structural Heart Defects: Caused by abnormal development of the heart during the first two months after conception.
• Functional Heart Defects: Examples include congenital heart block.
• Positional Heart Defects: Examples include dextrocardia (heart positioned on the right side of the chest).

CHDs Classification (diagram)

• CHDs are classified as either acyanotic or cyanotic.
• Acyanotic CHDs have normal blood oxygenation.
• Cyanotic CHDs have abnormal blood oxygenation.
• The diagram shows different types and direction of blood flow in the heart (inc. PBF, dec. PBF etc).

Non-cyanotic CHDs

• Volume overload (most common): These include left-to-right shunts (ASD, VSD, AVSD, PDA), and valve regurgitations (AV and semilunar valves). Also include cardiomyopathies (DCM, RCM, HCM).
• Pressure overload: Outlet obstructions (obstructive conditions including AS, PS, COA) and inlet obstructions (inlet conditions MS, TS, Cor triatriatum).

1-Volume overload lesions

• Left to right lesions (most common): Atrial Septal Defect (ASD), Ventricular Septal Defect (VSD), Atrioventricular Septal Defect (AVSD), and Patent Ductus Arteriosus (PDA).
• AV and semilunar valves regurgitation: Atrioventricular Septal Defect (AVSD), Ebstein anomaly, and Al with supracristal VSD.
• Cardiomyopathies: Dilated Cardiomyopathy (DCM), Restrictive Cardiomyopathy (RCM), and Hypertrophic Cardiomyopathy (HCM).

2-Pressure overload lesions

• Outlet obstructions (most common): Aortic Stenosis (AS), Pulmonic Stenosis (PS), and Coarctation of the Aorta (CoA).
• Inlet obstructions: Mitral Stenosis (MS), Tricuspid Stenosis (TS), and Cor triatriatum.

Cyanotic CHDs

• Dec. PBF: Obstruction to pulmonary blood flow (right to left shunt) conditions include Tetralogy of Fallot (TOF), Transposition of the Great Arteries (TGA), Tricuspid atresia, total anomalous pulmonary venous return, etc
• Inc. PBF: Conditions include transposition of the great vessels, and total anomalous pulmonary venous return (TAPVR).

Classification of Structural Congenital Heart Defects

• Increased Pulmonary Blood Flow: Atrial Septal Defect (ASD), Ventricular Septal Defect (VSD), AV Canal, Total Anomalous Pulmonary Venous Return (TAPVR), and Truncus Arteriosus.
• Decreased Pulmonary Blood Flow: Tetralogy of Fallot (TOF), Transposition of the Great Arteries (TGA), Pulmonary Stenosis and Atresia, and Tricuspid Atresia and other conditions.
• Obstruction to Systemic Blood Flow: Coarctation of the Aorta (COA), Aortic Stenosis, Hypoplastic Left Heart Syndrome (HLHS), and Mitral Stenosis and some other conditions.

Shunts

• Right-to-left shunt: Deoxygenated blood moves from the right side of the heart to the left side, bypassing the pulmonary circulation.
• Left-to-right shunt: Oxygenated blood moves from the left side of the heart to the right side, increasing the workload of the right ventricle.

Cyanotic vs. Acyanotic CHDs

• Acyanotic (usually left-to-right shunts): PDA, ASD, and VSD
• Cyanotic (right-to-left shunts): TOF, Transposition of the Great Arteries, and Hypoplastic Left Heart Syndrome (HLHS).
• O2 Sat less than 95%: A factor often indicating a cyanotic condition.
• In a cyanotic heart, the deoxygenated blood flows back into the systemic circulation.

Most Common CHDs

• These account for approximately 85% of all CHDs. The specific defects include Atrioventricular Septal Defect (ASD), Coarctation of the Aorta, Tetralogy of Fallot (TOF), Transposition of the Great Arteries (TGA), Ventricular Septal Defect (VSD).

Some Statistics

• CHDs are the most frequent birth defects (approximately 30% of all congenital defects).
• CHDs significantly contribute to infant mortality amongst birth defects.

Etiology of CHDs

• Unknown: The exact causes are not always clear.
• Slightly increased incidence: If siblings or parents have CHDs.
• Gender Factors: Aortic stenosis and coarctation of the aorta are slightly more common in males while PDA and ASD are slightly more common in females.
• Environmental Factors: Maternal infections like rubella, maternal drug use (e.g., lithium, alcohol, dilantin, cocaine), and maternal diabetes.
• Genetic Factors: Conditions such as Trisomy 21 (Down's syndrome), XO (Turner's syndrome), Marfan syndrome, and Osteogenesis imperfecta.

Prevention of CHD

• Lifestyle changes: Abstaining from alcohol during pregnancy
• Immunization: Rubella vaccination before conception.
• Medical management: Maintaining tight blood sugar control (in diabetic mothers).
• Supplementation: Folic acid/daily supplementation may help reduce risk.
• Genetic counseling: Important for families with a history of CHDs.

Embryonic Heart Development

• The human heart develops in the embryo between weeks 3 and 8 (post-conception).

Beginning Development Timeline

• Early week 3 (post-conception), the heart starts as two endothelial tubes.
• Mid-week 3, endothelial tubes fuse to make tubular structure.
• After 28 days, the single-chambered heart starts pumping blood.

Week 4 of Development

• Heart has a single outflow tract (truncus arteriosus), which divides into aorta and pulmonary arteries.
• Has a single inflow tract (sinus venosus), developing into superior and inferior vena cavae.
• Has a single atrium and a single ventricle.
• AV canal starts to close.

Weeks 5-7 of Development

• Heart begins completing its shape.
• AV canal closes completely.
• Atrial and atrial septums form.
• Heart rapid growth, folding, final shaping.
• Coronary sinus forms, and outflow tracts (aorta and pulmonary artery) separate fully.

8 Weeks After Conception

• Has a 4-chambered heart.

Fetal Circulation

• The placenta oxygenates the fetus during pregnancy.
• Blood flows through the lungs to perfuse lung tissues due to pulmonary vascular resistance and fetal vascular shunts.

Fetal Circulation (detailed)

• Umbilical vein carries oxygenated blood from the placenta to the fetus.
• Umbilical arteries carry deoxygenated blood from the fetus to the placenta.
• Foramen ovale allows blood to pass from the right atrium to the left atrium, bypassing the pulmonary circulation.
• Ductus arteriosus allows blood to bypass the lungs by passing from the pulmonary artery to the aorta.
• Ductus venosus allows blood to bypass the liver by passing from the umbilical vein to the inferior vena cava.

After Birth

• Lungs inflate (increase pulmonary blood flow).
• Foramen ovale and ductus venosus close.
• Ductus arteriosus closes.

Signs/Symptoms of CHDs

• Murmurs: Can worsen with activity (crying, exertion).
• Cyanosis: Worsens with activity (crying, exertion); bluish discoloration of skin due to reduced oxygen in blood.
• Respiratory distress: Breathing difficulties.
• Poor perfusion signs: Slow capillary refill, weak peripheral pulses.
• Fatigue: Common during feeding in newborns and play in children; newborns may be overly tired during feeding.
• Failure to thrive: Poor growth and development.

Common Congenital Heart Anomalies/Defects

Patent Ductus Arteriosus (PDA)

• Usually closes within 24-72 hours after birth; may not close in premature babies.
• Open vessel (patent ductus arteriosus) between aorta and pulmonary artery (PDA) causes increased pulmonary blood flow, congestion, and increased workload for the right ventricle.

Coarctation of the Aorta

• Localized narrowing of the aorta, most common in males associated with Turner's syndrome.
• Weak pulses and low blood pressure in the lower extremities are common.

Ventricular Septal Defect (VSD)

• Most common congenital heart defect, often occurring alone or with other anomalies; small defects may close spontaneously.

Truncus Arteriosus

• Failure of the truncus arteriosus to divide completely, causing a single vessel supplying blood to the aorta and pulmonary artery.
• Mixed oxygenated and deoxygenated blood enters the systemic circulation.

Tetralogy of Fallot (TOF)

• Ventricular septal defect (VSD).
• Aorta positioned over the VSD.
• Pulmonary outflow tract stenosis.
• Right ventricular hypertrophy.

Transposition of the Great Vessels (TGA)

• The aorta originates from the right ventricle, and the pulmonary artery originates from the left ventricle.
• A PDA is necessary for survival until corrective surgery can be done.
• More common in infants of diabetic mothers.

Hypoplastic Left Heart Syndrome (HLHS)

• Underdevelopment of the left side of the heart, including the left ventricle, aorta, and mitral valve.
• Fatal without early surgical intervention.

Total Anomalous Pulmonary Venous Return (TAPVR)

• Pulmonary veins are connected to the right side of the heart (right atrium or superior vena cava) instead of the left.

AV Canal

• Includes ASD, VSD, and mitral/tricuspid valve abnormalities.
• More common in children with Down syndrome.

Dextrocardia

• Heart is positioned on the right side of the chest.
• May occur with or without situs inversus (reversed visceral organs).
• Extremely rare conditions.