VSD

Definition
A defect in the ventricular septum allowing communication between the RV and LV. It is the most common congenital heart defect (excluding bicuspid aortic valve).

1. Classification

1. Membranous (70%): In the upper septum, near the aortic valve.
2. Muscular (20%): In the trabecular septum ("Swiss cheese" appearance if multiple).
3. Inlet (Posterior): Near the tricuspid valve (common in Down Syndrome/AVSD).
4. Outlet (Supracristal/Subarterial): Beneath pulmonary valve (associated with Aortic Regurgitation).

2. Hemodynamics

• Left-to-Right Shunt: Blood flows from high-pressure LV to low-pressure RV.
• Volume Overload: Increased flow to Pulmonary Artery $\to$ Lungs $\to$ LA $\to$ LV.
• Key Concept: VSD causes volume overload of the Left Atrium and Left Ventricle (and RV pumping against pressure, not volume, unless huge).

3. Clinical Features

• Small VSD (< 5mm): Asymptomatic ("Maladie de Roger").
• Large VSD (> 50% aortic annulus):
  • Delayed presentation (6-8 weeks) as PVR falls.
  • Symptoms: Tachypnea, diaphoresis during feeds, failure to thrive, recurrent chest infections.

4. Physical Examination

• Palpation: Hyperdynamic precordium, Systolic Thrill at LLSB.
• Auscultation:
  • Murmur: Harsh, Pansystolic Murmur best heard at Left Lower Sternal Border (LLSB).
  • Pearl: Intensity is inversely proportional to size (Small VSD = Loud Murmur).
  • P2: Loud (if Pulmonary Hypertension develops).
  • Mid-diastolic rumble: At apex (due to increased flow across Mitral valve in large VSDs).

5. Investigations

• CXR: Cardiomegaly (LV type), Pulmonary Plethora (increased vascular markings).
• ECG:
  • Small: Normal.
  • Large: Left Atrial Enlargement (LAE) and Biventricular Hypertrophy (BVH).
  • Classic Sign: Katz-Wachtel Phenomenon (Large equiphasic QRS complexes in V2-V5).
• Echo: Diagnostic (location, size, gradient).

6. Management

A. Medical

• Treat Congestive Heart Failure: Diuretics (Furosemide), ACE Inhibitors (Enalapril).
• Nutritional support (high-calorie feeds).
• Treat infections.

B. Surgical/Interventional

• Indications for Closure:
  1. Uncontrolled CHF / Failure to thrive.
  2. Qp:Qs > 2:1.
  3. Development of Pulmonary Hypertension (pre-Eisenmenger).
  4. Supracristal VSD with Aortic Regurgitation (prolapse of right coronary cusp).
• Methods:
  • Surgical Patch Closure: (Dacron/Gore-tex) - Gold standard.
  • Transcatheter Device Closure: For suitable Muscular VSDs.

C. Natural History

• 30-50% of small membranous/muscular VSDs close spontaneously in the first 2 years.