Congenital Heart Disease: A Clinical Review
Definition
Congenital heart disease (CHD) encompasses a wide spectrum of structural abnormalities of the heart and/or the great intrathoracic vessels that are present from birth (1). These malformations arise from errors during the complex process of embryonic heart development, which is largely completed in the early weeks of gestation (2).
Epidemiology
In Malaysia, congenital heart disease represents a significant healthcare burden. The Ministry of Health (MOH) estimates an incidence of 8 to 10 per 1,000 live births, which, given Malaysia's approximately 500,000 annual deliveries, translates to an estimated 5,000 new cases each year (9). A comprehensive 10-year population-based study in Johor found a slightly lower birth prevalence of 6.7 per 1,000 live births, a figure comparable to other middle-income nations (12). Globally, CHD affects nearly 1% of all live births, with Asia reporting the highest regional prevalence at 9.3 per 1,000 live births, placing Malaysia within a high-burden area (13, 14). The clinical impact is profound, with the MOH estimating that two-thirds of these children (~3,000 annually) will require surgical intervention (9).
Etiology
The cause of CHD is considered multifactorial in up to 80% of cases, resulting from a complex interplay between genetic predisposition and environmental factors (2).
Genetic Factors: These play a clear role in a significant minority of cases.
Chromosomal Abnormalities: Account for 5-6% of CHD. Down Syndrome (Trisomy 21) is the most prominent, with up to 50% of affected children having a CHD, most commonly an atrioventricular septal defect (AVSD) (12, 25). Other key associations include Turner Syndrome, Trisomy 18, and DiGeorge Syndrome (22q11.2 deletion) (23).
Single-Gene Defects: Responsible for 3-5% of cases, these can be part of syndromes like Marfan, Noonan, or Holt-Oram syndrome, or cause non-syndromal, familial CHD (25, 26).
Maternal and Environmental Factors: While accounting for only ~2% of cases, these are often modifiable (25).
Maternal Illness: Poorly controlled pre-gestational diabetes is a major risk factor. Other conditions include Phenylketonuria (PKU) and infections like Rubella (10, 19).
Teratogenic Exposures: This includes medications such as lithium and isotretinoin, as well as parental smoking and alcohol consumption during the peri-conceptual period (2, 10).
Pathophysiology
CHD is clinically classified based on its hemodynamic effects, which provides a framework for predicting clinical presentation. The most fundamental division is into acyanotic and cyanotic defects.
Acyanotic CHD
In these conditions, there is no net right-to-left shunt of deoxygenated blood, and thus central cyanosis is absent at rest. They are subdivided by their hemodynamic burden.
Lesions with Increased Pulmonary Blood Flow (Left-to-Right Shunts): An abnormal connection between the high-pressure systemic circulation and the low-pressure pulmonary circulation causes a net left-to-right flow of blood. This leads to excessive blood flow to the lungs (pulmonary plethora), placing a volume overload on the right ventricle and pulmonary vasculature. The result is pulmonary congestion, increased work of breathing, and eventually, high-output congestive heart failure (32).
Common Examples: Ventricular Septal Defect (VSD), Atrial Septal Defect (ASD), Patent Ductus Arteriosus (PDA), Atrioventricular Septal Defect (AVSD).
Obstructive Lesions (Pressure Overload): A physical narrowing (stenosis) obstructs blood flow. The cardiac chamber proximal to the obstruction must generate higher pressure to maintain forward flow, leading to compensatory concentric hypertrophy (thickening) of the ventricular wall (8).
Common Examples: Coarctation of the Aorta (CoA), Aortic Stenosis (AS), Pulmonary Stenosis (PS).
Cyanotic CHD
These defects are defined by a net right-to-left shunt, allowing deoxygenated blood to enter the systemic circulation, causing central cyanosis (8).
Lesions with Decreased Pulmonary Blood Flow: These defects feature both an obstruction to pulmonary blood flow (e.g., pulmonary stenosis) and an intracardiac communication (e.g., VSD). This combination allows deoxygenated blood from the right side of the heart to bypass the lungs and enter the systemic circulation (6).
Common Examples: Tetralogy of Fallot (TOF), Tricuspid Atresia, Pulmonary Atresia.
Lesions with Increased Pulmonary Blood Flow (Mixing Lesions): In this group, the anatomical arrangement forces the complete mixing of systemic (deoxygenated) and pulmonary (oxygenated) blood. This mixed, partially desaturated blood is then pumped to both the body and the lungs, resulting in a combination of cyanosis and congestive heart failure (32).
Common Examples: Transposition of the Great Arteries (TGA), Truncus Arteriosus, Total Anomalous Pulmonary Venous Return (TAPVR), Hypoplastic Left Heart Syndrome (HLHS).
Eisenmenger Syndrome
This is the most severe form of pulmonary hypertension, representing the end-stage of a large, uncorrected left-to-right shunt. Chronic high pressure and flow cause irreversible damage to the pulmonary arteries, leading to a fixed increase in pulmonary vascular resistance. Eventually, resistance in the pulmonary circuit exceeds systemic resistance, causing the shunt to reverse to right-to-left, resulting in cyanosis. At this stage, the defect is considered inoperable (38).
Clinical Presentation
The presentation of CHD varies dramatically with age and the specific defect.
Diagnostic Clues: The continuous "machinery" murmur of a PDA, the radio-femoral delay of Coarctation of the Aorta, or the fixed, widely split S2 of an ASD are highly suggestive. The classic "blue baby" with a harsh systolic murmur is characteristic of Tetralogy of Fallot (27, 38).
Common Symptoms in Neonates & Infants:
Cyanosis (bluish discoloration of the tongue and lips).
Respiratory distress (tachypnea, retractions, nasal flaring).
Feeding difficulties (sweating with feeds, tiring easily, taking a long time to feed).
Failure to thrive (inadequate weight gain).
⚠️ Red Flag Signs & Symptoms: Cardiovascular collapse or shock (pallor, poor perfusion, absent pulses) in a neonate as the ductus arteriosus closes suggests a duct-dependent lesion (e.g., critical coarctation, HLHS) and is a medical emergency (39).
Common Symptoms in Older Children & Adults:
Exercise intolerance or getting tired more easily than peers.
Dyspnea on exertion.
Palpitations or syncope (fainting), especially with exertion.
Presentation with a late complication like stroke or infective endocarditis (5).
Complications
Cardiovascular: Congestive heart failure, arrhythmias (atrial and ventricular), pulmonary hypertension, Eisenmenger syndrome.
Infectious: Infective endocarditis.
Neurological: Stroke (paradoxical embolism), brain abscess.
Hematological: Polycythemia (in chronic cyanosis), coagulopathy.
Prognosis
With advances in care, survival to adulthood is now expected for most patients. A 15-year study in Johor reported an overall survival rate of 83% (17). However, the prognosis is guarded for severe lesions, with 79% of all mortality occurring within the first year of life (17). Repaired hearts are not cured, and patients face lifelong risks of complications, requiring continuous specialist care (16). The growing population of Adults with Congenital Heart Disease (ACHD) presents a new challenge for healthcare systems (21).
Differential Diagnosis
Neonatal Sepsis: This is a key differential in any unwell neonate. Presentations can be identical, with lethargy, poor feeding, respiratory distress, and shock. A full septic workup is mandatory.
Primary Respiratory Disease: Conditions like Respiratory Distress Syndrome (RDS) in preterm infants or Transient Tachypnea of the Newborn (TTN) can cause respiratory distress. However, these are less likely to be associated with a significant murmur or signs of shock.
Persistent Pulmonary Hypertension of the Newborn (PPHN): This condition causes high resistance in the pulmonary vessels, leading to a right-to-left shunt through fetal channels (ductus arteriosus, foramen ovale) and profound cyanosis. It can be difficult to distinguish from cyanotic CHD without an echocardiogram.
Investigations
Immediate & Bedside Tests
Pulse Oximetry: An essential screening tool. A pre- and post-ductal saturation screen is mandatory for all neonates with respiratory distress or cyanosis to identify right-to-left shunting across the ductus arteriosus (the action), which is a hallmark of duct-dependent critical CHD (the rationale) (3). A failed hyperoxia test (cyanosis not improving with 100% oxygen) strongly suggests cyanotic CHD (39).
Electrocardiogram (ECG): An ECG is performed to assess for evidence of chamber enlargement or hypertrophy (the rationale), which provides crucial clues to the underlying hemodynamic burden of the defect (the action) (45). For example, right ventricular hypertrophy is classic for TOF, while left ventricular hypertrophy suggests severe aortic stenosis.
Diagnostic Workup
First-Line Investigation (Chest Radiograph): A chest X-ray is vital to assess heart size and, most importantly, the pulmonary vascular markings (the rationale), which helps differentiate between lesions with increased flow (plethora) and decreased flow (oligemia) (the action) (45). Classic cardiac silhouettes, like the "boot-shaped heart" of TOF, can also be identified (38).
Gold Standard (Echocardiography): A 2D echocardiogram is the definitive, non-invasive diagnostic test. It provides detailed anatomical definition of the defect and uses Doppler to assess the hemodynamic consequences, such as shunt size and valve gradients (the rationale), allowing for precise diagnosis and planning of management (the action) (45, 50).
Monitoring & Staging
Cardiac MRI/CT: These are used when echocardiography is inconclusive or to better visualize extracardiac structures like the aortic arch and pulmonary arteries (the rationale), which is essential for surgical planning in complex cases (the action) (51).
Cardiac Catheterization: This invasive procedure is now used selectively for diagnosis but is essential to directly measure pulmonary artery pressures and calculate pulmonary vascular resistance (the rationale), which is critical for determining operability in patients with long-standing shunts (the action) (44).
Management
Management Principles
The management of CHD focuses on medical stabilization, restoration of normal or near-normal circulation, and the prevention of long-term complications like irreversible pulmonary hypertension.
Acute Stabilisation (The First Hour)
Airway/Breathing: Administer high-flow oxygen via a non-rebreather mask to maintain SpO2 >94% (the action), which is crucial to prevent tissue hypoxia (the rationale). Intubation may be required for severe respiratory failure or shock.
Circulation: Secure two large-bore IV cannulas and, if in shock, administer a stat fluid bolus of IV Normal Saline 10-20mL/kg (the action) to restore tissue perfusion (the rationale).
Disability (Drugs): For any neonate with suspected duct-dependent circulation (cyanosis or shock), an immediate IV infusion of Prostaglandin E1 (PGE1) must be started (the action). This life-saving drug re-opens the ductus arteriosus, maintaining either pulmonary or systemic blood flow while awaiting definitive diagnosis and transfer (the rationale) (39).
Definitive Therapy
First-Line Treatment (Intervention): The choice between open-heart surgery and transcatheter intervention is made by a multidisciplinary "Heart Team".
Surgical Correction: This is the standard for most complex defects and includes procedures like VSD patch closure, complete repair of TOF, and the Arterial Switch Operation for TGA (36).
Transcatheter Intervention: A minimally invasive approach used for specific defects. This includes device closure of ASDs and PDAs, or balloon valvuloplasty for stenotic valves (62).
Palliative Procedures: These are temporary measures used in infants who are too small or unstable for full repair. Examples include a Blalock-Taussig (BT) shunt to increase pulmonary blood flow or Pulmonary Artery (PA) banding to reduce it (58).
Supportive & Symptomatic Care
Heart Failure Management: In infants with large shunts, diuretics (e.g., IV/PO Furosemide 1mg/kg/dose) are used to reduce pulmonary congestion (57).
Nutritional Support: This is critical. High-calorie formulas and nasogastric tube feeding are often required to overcome feeding difficulties and meet the high metabolic demands of increased work of breathing (57).
Key Nursing & Monitoring Instructions
Strict hourly input/output chart monitoring.
Continuous cardiorespiratory and saturation monitoring.
Inform medical staff immediately if systolic BP drops, acidosis worsens, or urine output is <1mL/kg/hr.
For patients on PGE1, monitor closely for side effects like apnea, fever, and hypotension.
Long-Term Plan & Patient Education
A "repaired" heart is not a "cured" heart. All patients require lifelong follow-up with a cardiologist specializing in CHD (16). A structured transition from pediatric to adult care services is crucial to prevent patients from being lost to follow-up (20). Patients and families must be educated on the lifelong risk of complications, particularly the importance of meticulous dental hygiene and indications for infective endocarditis prophylaxis (5).
When to Escalate
Call Your Senior (MO/Specialist) if:
A neonate presents with shock or profound cyanosis.
A newborn fails a pulse oximetry screen or a hyperoxia test.
There is any sudden deterioration in a known CHD patient.
Referral Criteria:
Any infant or child with suspected CHD (e.g., murmur with failure to thrive) requires an urgent referral to a Paediatric Cardiologist.
Any neonate with suspected critical/duct-dependent CHD requires immediate discussion with the on-call Paediatric Cardiologist and arrangement for emergency transfer to a tertiary cardiac centre (e.g., IJN, Serdang Hospital).
References
PubMed. (2024). Congenital heart disease: types, pathophysiology, diagnosis, and treatment options. Retrieved July 20, 2025, from https://pubmed.ncbi.nlm.nih.gov/38974713
PMC. (2024). Congenital heart disease: types, pathophysiology, diagnosis, and treatment options - PMC. Retrieved July 20, 2025, from https://pmc.ncbi.nlm.nih.gov/articles/PMC11224996/
StatPearls. (2024). Cyanotic Heart Disease - StatPearls - NCBI Bookshelf. Retrieved July 20, 2025, from https://www.ncbi.nlm.nih.gov/books/NBK500001/
American Heart Association. (n.d.). About Congenital Heart Defects. Retrieved July 20, 2025, from https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects
Mayo Clinic. (n.d.). Congenital heart defects in children - Symptoms and causes. Retrieved July 20, 2025, from https://www.mayoclinic.org/diseases-conditions/congenital-heart-defects-children/symptoms-causes/syc-20350074
Michigan Medicine. (n.d.). Congenital Heart Disease (CHD) | CS Mott Children's Hospital. Retrieved July 20, 2025, from https://www.mottchildren.org/conditions-treatments/ped-heart/chd
Johns Hopkins Medicine. (n.d.). Congenital Heart Defects (CHD). Retrieved July 20, 2025, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/congenital-heart-defects
Ministry of Health Malaysia. (n.d.). Guidelines on the Management of Children with Congenital Heart Diseases for Cardiothoracic Surgery. Retrieved July 20, 2025, from https://www.moh.gov.my/moh/attachments/1915.pdf
CodeBlue Galen Centre. (2022). Every Child Deserves A Healthy Heart — Subang Jaya Medical Centre. Retrieved July 20, 2025, from https://codeblue.galencentre.org/2022/09/every-child-deserves-a-healthy-heart-subang-jaya-medical-centre/
ResearchGate. (2018). The birth prevalence, severity, and temporal trends of congenital heart disease in the middle-income country: A population-based study. Retrieved July 20, 2025, from https://www.researchgate.net/publication/328122576_The_birth_prevalence_severity_and_temporal_trends_of_congenital_heart_disease_in_the_middle-income_country_A_population-based_study
PubMed Central. (2024). Global, regional, and national epidemiology of congenital heart disease in children from 1990 to 2021. Retrieved July 20, 2025, from https://pmc.ncbi.nlm.nih.gov/articles/PMC12122482/
JACC. (2011). Birth Prevalence of Congenital Heart Disease Worldwide: A Systematic Review and Meta-Analysis. Retrieved July 20, 2025, from https://www.jacc.org/doi/10.1016/j.jacc.2011.08.025
Children's Health. (n.d.). Long-Term Effects of Congenital Heart Disease. Retrieved July 20, 2025, from https://www.childrens.com/health-wellness/long-term-effects-of-congenital-heart-disease
Archives of Disease in Childhood. (2024). Survival outcomes for congenital heart disease from Southern Malaysia: results from a congenital heart disease registry. Retrieved July 20, 2025, from https://adc.bmj.com/content/109/5/363
Mayo Clinic. (n.d.). Congenital heart disease in adults - Symptoms and causes. Retrieved July 20, 2025, from https://www.mayoclinic.org/diseases-conditions/adult-congenital-heart-disease/symptoms-causes/syc-20355456
PMC. (2017). Systematic long-term follow-up programs in patients with simple congenital heart diseases. Retrieved July 20, 2025, from https://pmc.ncbi.nlm.nih.gov/articles/PMC5227189/
National Heart Association of Malaysia. (2023). Clinical Practice Guidelines Management of Heart Failure 2023 (5th Edition). Retrieved July 20, 2025, from https://www.malaysianheart.org/publication/clinical-practice-guidelines/p/clinical-practice-guidelines-management-of-heart-failure-2023-5th-edition
American Heart Association. (n.d.). Understand Your Risk for Congenital Heart Defects. Retrieved July 20, 2025, from https://www.heart.org/en/health-topics/congenital-heart-defects/understand-your-risk-for-congenital-heart-defects
Cincinnati Children's Hospital. (n.d.). Factors Contributing to Congenital Heart Disease. Retrieved July 20, 2025, from https://www.cincinnatichildrens.org/health/c/factors-chd
Stanford Medicine Children's Health. (n.d.). Factors That May Lead to a Congenital Heart Defect (CHD). Retrieved July 20, 2025, from https://www.stanfordchildrens.org/en/topic/default?id=factors-that-may-lead-to-a-congenital-heart-defect-chd-90-P01788
BMJ Best Practice. (n.d.). Tetralogy of Fallot. Retrieved July 20, 2025, from https://bestpractice.bmj.com/topics/en-gb/701
DNB Pediatrics. (2016). Congenital Heart Disease in children | classification and Overview. Retrieved July 20, 2025, from https://www.dnbpediatrics.com/2016/01/approach-to-congenital-heart-disease.html
MedlinePlus. (n.d.). Congenital heart defect - corrective surgery. Retrieved July 20, 2025, from https://medlineplus.gov/ency/article/002948.htm
NCBI Bookshelf. (n.d.). Adult congenital heart disease - Cardiology Explained. Retrieved July 20, 2025, from https://www.ncbi.nlm.nih.gov/books/NBK2212/
PubMed Central. (2011). Congenital heart disease in the newborn requiring early intervention. Retrieved July 20, 2025, from https://pmc.ncbi.nlm.nih.gov/articles/PMC3145901/
Mayo Clinic. (n.d.). Congenital heart defects in children - Diagnosis and treatment. Retrieved July 20, 2025, from https://www.mayoclinic.org/diseases-conditions/congenital-heart-defects-children/diagnosis-treatment/drc-20350080
American Heart Association. (n.d.). Common Tests for Congenital Heart Defects. Retrieved July 20, 2025, from https://www.heart.org/en/health-topics/congenital-heart-defects/symptoms--diagnosis-of-congenital-heart-defects/common-tests-for-congenital-heart-defects
PMC. (2024). Echocardiography in Simple Congenital Heart Diseases: Guiding Adult Patient Management. Retrieved July 20, 2025, from https://pmc.ncbi.nlm.nih.gov/articles/PMC10936704/
NYU Langone Health. (n.d.). Diagnosing Adult Congenital Heart Disease. Retrieved July 20, 2025, from https://nyulangone.org/conditions/adult-congenital-heart-disease/diagnosis
Mayo Clinic. (n.d.). Ventricular septal defect (VSD) - Diagnosis & treatment. Retrieved July 20, 2025, from https://www.mayoclinic.org/diseases-conditions/ventricular-septal-defect/diagnosis-treatment/drc-20353501
RSNA Journals. (2002). Palliative Procedures for Congenital Heart Disease: Imaging Findings and Complications. Retrieved July 20, 2025, from https://pubs.rsna.org/doi/full/10.1148/rg.220049
NYU Langone Health. (n.d.). Catheter-Based Treatments for Adult Congenital Heart Disease. Retrieved July 20, 2025, from https://nyulangone.org/conditions/adult-congenital-heart-disease/treatments/catheter-based-treatments-for-adult-congenital-heart-disease
