Chapter 21 · Cardiac Assessment & Investigations

Electrocardiography (ECG) · Chest radiography · Echocardiography (transthoracic, fetal, transoesophageal) · Cardiac catheterisation (diagnostic, interventional) · Other investigations (Holter, exercise testing, MRI, CT, biomarkers)
📌 Core principles: ECG: axis, chamber enlargement, conduction intervals (QTc). CXR: cardiomegaly, pulmonary vascularity. Echocardiography: gold standard for structural CHD, function, haemodynamics. Cardiac catheterisation: haemodynamic assessment, interventions (balloon septostomy, valvuloplasty, device closure). MRI: ventricular volumes, fibrosis, great vessels. CT: coronary anomalies, vascular rings. Holter: arrhythmia detection. Exercise testing: functional capacity, ischaemia.

📖 Cardiac Investigations – Key Concepts

📊 Electrocardiography (ECG)
ECG in children: normal rate varies by age. Axis: left axis deviation (tricuspid atresia), right axis (normal newborn, RVH). Chamber enlargement: RVH (tall R in V1, deep S in V6), LVH (deep Q, tall R in V5/6). Conduction: PR interval, QRS duration, QT interval (corrected QTc <450ms). Arrhythmia detection.
🩻 Chest radiography
Cardiothoracic ratio (>0.55 suggestive cardiomegaly). Pulmonary vascularity: increased (left-to-right shunt), decreased (cyanotic CHD with PS), venous congestion (heart failure). Specific signs: ‘egg on side’ (TGA), ‘boot-shaped’ (TOF), ‘snowman’ (TAPVR).
🫀 Echocardiography (transthoracic, TEE, fetal)
Gold standard for structural CHD. 2D imaging, M-mode, Doppler (colour, pulsed, continuous). Assess ventricular function (EF), valve stenosis/regurgitation, shunts (ASD, VSD, PDA). Fetal echo for prenatal diagnosis. Transoesophageal (TEE) for intraoperative guidance, posterior structures.
🪡 Cardiac catheterisation
Diagnostic: pressures (RV, PA, PCWP), saturations (shunt calculation, O2 step-up). Interventional: balloon atrial septostomy (Rashkind) for TGA, valvuloplasty (pulmonary/aortic stenosis), device closure (ASD, PDA, VSD), stent placement (coarctation, PDA), embolisation (collaterals).
🧪 Other investigations
Holter monitor: 24h ECG for arrhythmias, syncope. Exercise stress test: functional capacity, arrhythmias, ischaemia. Cardiac MRI: ventricular volumes, fibrosis (LGE), great vessel anatomy. CT: coronary arteries (anomalous origin, Kawasaki aneurysms), vascular rings. Biomarkers: NT-proBNP (heart failure severity, cardiomyopathy), troponin (myocardial injury).

🔎 Symptom-based approach: Choosing cardiac investigations

1️⃣
Infant with cyanosis, no murmur. Hyperoxia test fails. First investigation?
Echocardiography (urgent) – defines anatomy (TGA, TOF, tricuspid atresia). CXR may show vascularity, shape.
2️⃣
Child with murmur, possible VSD. Best initial non-invasive test?
Transthoracic echocardiography (size, location, shunt, function). CXR and ECG adjunctive.
3️⃣
Neonate with TGA. Intervention before arterial switch?
Balloon atrial septostomy (Rashkind) at cardiac catheterisation or echocardiography-guided.
4️⃣
Adolescent with syncope during exercise, normal echo. Next test?
Exercise ECG (arrhythmias, ischaemia, blood pressure), Holter, consider cardiac MRI (ARVC, myocarditis), genetic testing (LQTS, CPVT).
5️⃣
Child with suspected anomalous coronary artery. Best imaging?
Cardiac CT (coronary origins) or MRI (origin, course).
📊 Key points: Echo is first-line for CHD. Catheterisation: pressures, shunts, interventions. MRI best for ventricular volumes, scar, great vessels. CT for coronaries. Biomarkers (NT-proBNP) for heart failure monitoring.

📋 Investigation algorithm & interpretation

📊
ECG interpretation in paediatric heart disease
▪️ Right axis deviation (normal newborn, but persistent: RVH, TOF, pulmonary stenosis).
▪️ Left axis deviation (tricuspid atresia, AV canal defect).
▪️ RVH: R wave in V1 >98th centile, upright T wave in V1 beyond 7 days.
▪️ LVH: R wave in V6 >98th centile, deep Q waves.
▪️ Prolonged QTc (>460 ms) – LQTS (syncope, sudden death).
🩻
CXR – patterns of pulmonary vascularity
▪️ Increased (plethoric): left-to-right shunt (VSD, PDA, ASD), TAPVR (obstructed).
▪️ Decreased (oligaemic): TOF, pulmonary atresia, tricuspid atresia (RVOTO).
▪️ Asymmetric: unilateral oligaemia (TOF with absent pulmonary artery).
▪️ Venous congestion: heart failure (cardiomyopathy, severe MS, large left-to-right shunt).
🫀
Echocardiographic parameters
▪️ Systolic function: ejection fraction (LVEF >55%).
▪️ Diastolic function: E/A ratio, tissue Doppler (E/e').
▪️ Pulmonary artery pressure: tricuspid regurgitation jet (RVSP).
▪️ Shunt quantification: Doppler (VSD, PDA, ASD).
🪡
Cardiac catheterisation indications
▪️ Pre-surgical assessment (PAH, shunts, coronary anomalies).
▪️ Intervention: balloon atrial septostomy (TGA), pulmonary/aortic valvuloplasty, device closure (ASD, PDA, VSD), coarctation stenting, coil embolisation.
▪️ Endomyocardial biopsy (transplant rejection, myocarditis).

💡 Reflex prompts – Cardiac investigations

📊 ECG finding in tetralogy of Fallot?
Right axis deviation, RVH, dominant R in V1.
🩻 CXR shows ‘egg on side’ appearance. Diagnosis?
Transposition of great arteries (TGA).
🫀 Gold standard for diagnosis of atrial septal defect?
Transthoracic echocardiography (colour Doppler, contrast).
🪡 Rashkind procedure (balloon atrial septostomy) is used for which CHD?
Transposition of great arteries (to improve mixing).
📊 A neonate with tricuspid atresia. ECG likely shows?
Left axis deviation, LVH (dominant LV).
🧪 Elevated NT-proBNP is most useful in monitoring?
Heart failure severity, response to therapy (cardiomyopathy, CHD).
🫀 Best imaging for anomalous coronary artery origin?
Cardiac CT angiography (coronary anatomy).
📊 CXR shows pulmonary oligaemia and boot-shaped heart. Diagnosis?
Tetralogy of Fallot.
🩺 A child with long QT syndrome. Which ECG interval prolonged?
Corrected QT (QTc) >460 ms.
🪡 A child with critical pulmonary stenosis. Interventional procedure?
Balloon pulmonary valvuloplasty.