Congenital Heart Diseases

Dr Sartaj Ahmad Guroo

Introduction: Congenital heart diseases (CHD) are the most common andserious structural birth defects which affect both the heart and major blood vessels. CHD are a major economic burden to society in general and to the family in particular. These patients may require multiple surgeries for the correction of the defect so accordingly need frequent hospital admissions. The surviving infant may still have to live with the disability. Congenital heart disease is the main cause of infant mortality worldwide while in India about 10% of infant mortality is attributed to CHDs.The incidence of CHD ranges from 0.8 to 1% live births which means approximately 1.35 million newborns are born with CHD worldwide while in India the estimated number of children born with CHD every year is approximately 2,40,000. The incidence of CHD is highest in Asia. Despite the significant geographic variation, the prevalence of CHD has remained relatively stable. The prevalence of CHD is high in developed countries. With advancements in diagnosis and medical management, 85% of people with CHD live up to adulthood. Post-surgery survival is even more than 97%. CHD is known to have important effects on brain development resulting in neurodevelopmental or neurocognitive defects.
Classification: Congenital heart defects are classified as follows: Acyanotic congenital heart disease and Cyanotic congenital heart disease.
The acyanoticcongenital heart disease are further subdivided into shunt lesions (Atrial septal defect, Ventricular Septal Defect, Patent Ductus Arteriosus) and non-shunt lesions(Aortic Stenosis, Aortic Regurgitation, Pulmonary Stenosis, Mitral Regurgitation)
The Cyanotic congenital heart disease are further subdivided into following categories

1. Reduced pulmonary blood flow like Tetralogy of Fallot (TOF), TOF equivalents
2. Increased pulmonary blood flow like Transposition physiology, Intercirculatory mixing
3. Near normal pulmonary blood flow like Pulmonary arteriovenous fistula, Anomalous drainage of vena cava to left atrium (LA).
   Etiopathogenesis of CHD: Only in 15 to 30% of CHD patients, the potentially modifiable cause can be found while in the rest of the cases, the etiology is either multifactorial or unknown. Infections like Rubella, or any febrile illnesses during the first trimester of pregnancy increases the chances of CHD by 2-fold in the offspring. Therapeutic(Thalidomide, Metronidazole, Trimethoprim-sulfonamide, Isotretinoin, Antiepileptic Drugs, Fluconazole, Lithium, Chemotherapy, Clomiphene etc) or non-therapeutic(Cocaine and Marijuana) drug exposure during the first trimester of pregnancy increases the chances of CHD. One percent of CHD can be due to maternal medical conditions such as Diabetes Mellitus, Phenylketonuria, Epilepsy and Obesity. The use of multivitamin supplements containing folic acid before conception and during pregnancy has been shown to reduce the risk for CHD. Alcohol abuse and smoking are known teratogenic for CHD. Environmental hazards like ambient air pollutants, ionizing radiations, water chlorination byproducts,and occupational exposure to organic solvents, chemicals, dyes and paints have been associated with increased risk of CHD. Besides these increased maternal age at conception, psychological stress and Assisted Reproductive Technology are associated withincreased risk for CHD. The family history of CHD is a well-established risk factor. The offspring and first-degree relatives of patients with CHD are at a higher riskof having CHD.
   In addition to the above-mentioned factors, genetic factors play an important role in CHD. Chromosomal Aberrations like Down Syndrome, Edward Syndrome, Patau Syndrome, Turner Syndrome, Cat Eye Syndrome, Pallister-Killian Syndrome, Chromosome Deletion Syndrome, Williams-Beuren Syndrome, Wolf-Hirschhorn Syndrome, and Alagille Syndrome have been associated with CHD. Single gene disorders (Noonan Syndrome, Holt-Oram Syndrome, Ellis-van Creveld Syndrome, Kabuki Syndrome) and metabolic disorders (Pompe Disease, Zellweger Syndrome, Smith-Lemli-Opitz Syndrome) are also associated with CHD.
   Clinical presentation of CHD patients
   The CHD should be suspected if any of the following is present.
4. Difficulty in feeding
5. Respiratory distress
6. Subcostal recession
7. Recurrent LRTI
8. Growth retardation
9. Exercise intolerance
10. Easy fatigability
11. Bluish discoloration of skin
12. Abnormal heart sounds in the older child
13. Sweating during feeding.
    Higher the severity of the defect more severe and early onset of the clinical presentation and symptoms. These patients mostly present during the first six months of life.
    Management of CHD patients
    Clinical assessment and use of different diagnostic tools, aid in the diagnosis of CHDs. Meticulous history and detailed systemic physical examination are the cornerstone of the diagnosis of CHDs. The following tools are used for the diagnosis of CHD.
14. Electrocardiography (ECG)
15. Chest X-ray
16. Echocardiography. The use of fetal echocardiography can detect these disorders prenatally.
17. Cardiac catheterization and angiocardiography, if needed.
18. Computer tomography and cardiac MRI (Magnetic Resonance Imaging) if needed.
19. Pulse oximetry should be used as a screening tool for CHD
    Nadas criteria should be used for labeling a child, having heart disease as NYHA (New York Heart Association) criteria is not applicable for children. Once a child is labeled as having CHD they should be referred higher center for further management. These children should undergo regular dental check-ups.
    Modes of prevention
    Prevention of any disease can be done by multiple strategies. For CHDs following levels of prevention can be utilized:
    1.Primary prevention: The aim of this level of prevention is to prevent a disease from even occurring. This can be done by Immunization against Rubella, Tobacco cessation, and intakeof Iron and Folic acid during pregnancy.
    2.Secondary prevention: This means early detection of diseases in order to prevent the progression of the disease. It often occurs in the form of screening. Fetal echocardiography should be done to screen CHD prenatally.
    3.Tertiary prevention: this means limiting the disability of the diseaseand aiding the recovery from complications. This level of prevention is done through different rehabilitation programs.
    Message for prospective mothers
    A prospective mother should follow the following points for a safe pregnancy:
20. Discuss any medical condition like Diabetes Mellitus with a qualified medical specialist for periconceptional care
21. Women of childbearing age should take multivitamins containing folic acid daily both before and during pregnancy
22. Discuss the use of any medication with their doctor for possible known teratogenicity.
23. A prospective mother should avoid tobacco and alcohol use
24. Pregnancy should be planned to avoid inadvertent harmful exposures to the fetus in the first trimester.
25. They should avoid contact with people having any febrile illness.
26. They should avoid occupational exposure to organic solvents.
27. They should get immunized against Rubella
28. A screening fetal echocardiogram should be done at 16 to 18 weeks of gestation if there is any doubt.
    (The writor is Assistant Professor, Cardiothoracic Surgery, AIIMS Vijaypur Jammu).