Cardiac Evaluation and Diagnostics

Clinical Assessment - Heart's First Clues

• History:
  • Feeding: Sweating, fatigue, ↓intake, poor weight gain (FTT).
  • Cyanosis: Onset, squatting. Exercise intolerance.
  • Maternal: Diabetes, infections. Family Hx of CHD.
• General Exam:
  • Syndromic facies (e.g., Down's, Turner's, Noonan's).
  • Vitals: HR, RR, 4-limb BP (coarctation), SpO2 (pre & post-ductal).
  • Clubbing, cyanosis (central/peripheral), edema.
• CVS Exam:
  • Palpation: Apex beat (location), thrills, heaves. Pulses: Radio-femoral delay.
  • Auscultation: Heart sounds (S1, S2 splitting, S3, S4, clicks). Murmurs: Systolic/Diastolic, Grade (1-6), location, radiation, quality.

⭐ Differential cyanosis (lower limb SpO2 < upper limb SpO2 by >3-5%) strongly suggests Persistent Ductus Arteriosus (PDA) with right-to-left shunt or interrupted aortic arch.

Chest X-Ray - X-Ray Vision

• CT Ratio: Neonate <0.6; Infant (<1yr) <0.55; Child (>1yr) <0.5.
• Pulmonary Vascular Markings (PVM):
  • ↑ Plethora: L→R shunts (VSD, ASD, PDA).
  • ↓ Oligemia: ↓ Pulm. Blood Flow (TOF, Pulm. Atresia).
  • Venous Congestion: LV failure, MS.
• Classic Cardiac Silhouettes & Signs:
  • "Boot-shaped": TOF.
  • "Egg-on-string": TGA.
  • "Snowman sign" / "Figure of 8": TAPVC (supracardiac).
  • "Box-shaped" / "Wall-to-wall": Ebstein anomaly.
  • Rib notching: Coarctation of Aorta.

⭐ "Boot-shaped" heart (Coeur en sabot) in Tetralogy of Fallot signifies RV hypertrophy & upturned cardiac apex.

Pediatric ECG - Electric Heartbeats

• Key Differences vs. Adult ECG:
  • Rate: Faster (Neonate 100-180 bpm, ↓ with age).
  • Rhythm: Sinus arrhythmia common.
  • Axis: Right axis deviation (RAD) normal in neonates (+90° to +180°), shifts left with age.
  • Intervals (PR, QRS): Shorter, ↑ with age. QTc normal <0.44s (<0.46s infants <1yr).
  • T waves: Inverted in V1-V3 (juvenile pattern) after 1st week until adolescence.
  • RV Dominance: Prominent R in V1, S in V6 in newborns; LV dominance by ~3 yrs.

⭐ Upright T wave in V1 beyond the first week of life (up to ~6 years) or a qR pattern in V1 can suggest Right Ventricular Hypertrophy (RVH).

Echocardiography - Ultrasound Insights

• Non-invasive gold standard for cardiac structure, function, hemodynamics.
• Modes:
  • 2D: Real-time anatomical views, chamber dimensions (e.g., LA/Ao ratio), wall motion, pericardial effusion.
  • M-mode: Precise measurements of wall thickness, chamber size, LVEF (e.g., Teichholz, Simpson).
  • Doppler: Assesses blood flow direction, velocity, turbulence.
    • Color Doppler: Visualizes shunts (VSD, ASD), valvular regurgitation.
    • Pulsed Wave (PW): Measures velocity at specific points (e.g., E/A ratio for diastolic function).
    • Continuous Wave (CW): Measures high velocities (e.g., aortic stenosis peak gradient).
• Applications: Congenital heart defects (CHD), valvular heart disease, cardiomyopathies, infective endocarditis, pulmonary hypertension.
• Transthoracic (TTE) is standard; Transesophageal (TEE) for superior views of posterior structures, LA appendage, prosthetic valves.

⭐ In Tetralogy of Fallot, echocardiography demonstrates an overriding aorta, VSD, RVH, and pulmonary stenosis; Doppler quantifies the PS gradient and shunt.

Advanced Diagnostics - Deeper Dives

• Cardiac MRI (CMR): Gold standard: RV assessment (volume, function), fibrosis (LGE). For complex anatomy, ARVD, myocarditis. No radiation.

• Cardiac CT (CCT): Coronary/vascular ring assessment, airway compression. Rapid. Radiation.

• Cardiac Catheterization: Measures pressures, $O_2$ sats ($Q_p/Q_s$), angiography. Therapeutic: device closures, valvuloplasty.

  ⭐ Oxygen step-up >7% (SVC/IVC to PA) suggests ASD; >5% (RV to PA) suggests VSD.

• EPS: Arrhythmia evaluation/ablation.

• Genetic Testing: Syndromic CHDs, inherited arrhythmia/cardiomyopathy_._

High‑Yield Points - ⚡ Biggest Takeaways

• VSD is the most common CHD; ASD often shows RAD on ECG.
• Echocardiography is the gold standard for CHD diagnosis.
• TOF features: "boot-shaped" heart (CXR), RVH (ECG), cyanosis.
• PGE1 maintains ductal patency in duct-dependent lesions (e.g., TGA, severe PS).
• TGA shows "egg-on-string" (CXR); TAPVC (supracardiac) shows "snowman sign".
• Pulse oximetry screening is vital for detecting critical CHDs in newborns.