What are the types, clinical diagnosis, clinical findings on auscultation, pulses, electrocardiogram (ECG) and echocardiography (echo) findings, and management of Ventricular Septal Defects (VSDs)?

Ventricular Septal Defects: Types, Clinical Diagnosis, and Management

Ventricular septal defects (VSDs) are classified into four main anatomical types with distinct clinical presentations, diagnostic findings, and management approaches based on their location, size, and hemodynamic significance. 1

Types of VSDs

• Type 1 (Outlet/Supracristal): Located in the outflow portion of the right ventricle, accounts for approximately 6% of defects in non-Asian populations and up to 33% in Asian patients. Spontaneous closure is uncommon. 1, 2

• Type 2 (Membranous/Perimembranous): Most common type (approximately 80% of all VSDs), located in the membranous septum adjacent to the septal leaflet of the tricuspid valve. The tricuspid valve can adhere to the defect forming a "pouch" or "aneurysm" that may limit left-to-right shunting and potentially lead to partial or complete closure. 1, 2

• Type 3 (Inlet): Located in the lower part of the right ventricle adjacent to the tricuspid valve, typically occurring in patients with Down syndrome. 1, 2

• Type 4 (Muscular): Can be located centrally (mid-muscular), apically, or at the margin of the septum and right ventricular free wall. May be multiple in number with a high rate of spontaneous closure. 1, 2

Clinical Diagnosis

Clinical Presentation

• Small VSDs (<25% of aortic annulus diameter): Usually asymptomatic with a systolic murmur, no left ventricular volume overload, and no pulmonary arterial hypertension (PAH). 1

• Moderate VSDs (25-75% of aortic annulus diameter): May present with small to moderate left-to-right shunts, mild to moderate left ventricular volume overload, and mild or no PAH. Patients may remain asymptomatic or develop symptoms of mild congestive heart failure. 1

• Large VSDs (>75% of aortic annulus diameter): Present with significant left-to-right shunting, left ventricular volume overload, and potential development of PAH if left untreated. 1, 3

Auscultation Findings

• Small VSDs: Harsh holosystolic murmur best heard at the left lower sternal border. 1

• Moderate to Large VSDs: Holosystolic murmur with increased intensity, often accompanied by a mid-diastolic rumble at the apex (due to increased flow across the mitral valve) and a loud P2 component of the second heart sound if pulmonary hypertension develops. 1, 3

• VSDs with Pulmonary Hypertension: As pulmonary vascular resistance increases, the murmur may decrease in intensity. In Eisenmenger syndrome (right-to-left shunting), the murmur may disappear completely. 1

Pulse Findings

• Small VSDs: Normal peripheral pulses. 1

• Moderate to Large VSDs: Hyperdynamic precordium, bounding pulses due to increased stroke volume. 1

• VSDs with Pulmonary Hypertension: Normal or diminished peripheral pulses. 1, 3

Diagnostic Studies

Electrocardiogram (ECG)

• Small VSDs: Usually normal. 1

• Moderate to Large VSDs: May show left atrial enlargement, left ventricular hypertrophy, and occasionally right ventricular hypertrophy if pulmonary hypertension develops. 1, 3

• VSDs with Eisenmenger Physiology: Right ventricular hypertrophy, right axis deviation, and right atrial enlargement. 1

Chest X-Ray

• Small VSDs: Normal cardiac silhouette and pulmonary vascularity. 1

• Moderate to Large VSDs: Left atrial and left ventricular enlargement with increased pulmonary vascular markings. 1

• VSDs with Pulmonary Hypertension: Prominent pulmonary artery segment with diminished peripheral pulmonary vascular markings. 1

Echocardiography

Echocardiography-Doppler is the mainstay of diagnosis, providing essential information about:

• Number of defects: Single or multiple 1
• Location of defect(s): Inlet, membranous, muscular, or outlet 1
• Size of defect: Small (hemodynamically insignificant) or moderate to large (hemodynamically significant) 1
• Chamber sizes: Left atrial and ventricular dilation in significant left-to-right shunts 1
• Ventricular function: Assessment of systolic and diastolic function 1
• Associated anomalies: Presence of aortic valve prolapse/regurgitation, right or left ventricular outflow obstruction, tricuspid regurgitation 1
• Hemodynamic assessment: Estimation of pulmonary-to-systemic flow ratio (Qp:Qs) and pulmonary artery pressure 1, 4

An indexed VSD area >50 mm²/m² at initial diagnosis is independently associated with the need for surgical intervention, regardless of defect type and location. 4

Management

Management decisions are based on defect size, location, hemodynamic significance, and presence of complications:

Small VSDs

• Observation: Regular clinical and echocardiographic follow-up to monitor for spontaneous closure, which is common in muscular defects. 5, 3
• Endocarditis prophylaxis: No longer routinely recommended for uncomplicated small VSDs according to current guidelines. 1

Moderate to Large VSDs

Indications for closure include:

• VSDs with enlarged left atrium and left ventricle
• Elevated pulmonary artery pressure
• Pulmonary-to-systemic flow ratio >2:1
• Symptoms of heart failure despite medical therapy
• Development of aortic valve prolapse/regurgitation
• History of endocarditis 5, 3

Closure Methods

• Surgical closure: Recommended for:

  • Large perimembranous VSDs
  • Supracristal VSDs
  • Inlet VSDs
  • VSDs with aortic valve prolapse
  • Multiple VSDs that are not amenable to device closure 5, 3

• Percutaneous device closure: Primarily for muscular VSDs. Currently, the Amplatzer Muscular VSD Occluder is the only device approved by the FDA for clinical use. 5, 3

• Hybrid approach: Combines surgical access with device deployment, particularly useful for large muscular VSDs in small infants. 5

Timing of Intervention

• Early intervention (typically before 6-12 months of age) is recommended for large VSDs to prevent the development of irreversible pulmonary vascular obstructive disease. 5, 3

• Palliative pulmonary artery banding may be considered in small infants (<5 kg) with significant comorbidities as a bridge to complete repair. 5

Special Considerations

• VSDs in Tetralogy of Fallot: Almost always of the outlet type, located between the two limbs of the septal band. 6

• VSDs in Complete Atrioventricular Septal Defects: Require comprehensive repair including closure of both atrial and ventricular components and reconstruction of atrioventricular valves. Early repair (before 6 months of age) is crucial to prevent pulmonary vascular disease. 7, 5

• Unbalanced Atrioventricular Septal Defects: Management is more complex, often requiring staged single-ventricle palliation, though two-ventricle repair may be possible in suitable cases. 5

Complications and Long-term Follow-up

• Pulmonary Hypertension: Regular assessment of pulmonary artery pressure is essential, especially in unrepaired or late-repaired VSDs. 1, 3

• Aortic Valve Regurgitation: Can develop due to prolapse of aortic valve leaflets into perimembranous VSDs. 1, 3

• Arrhythmias: May occur following surgical repair, requiring periodic ECG monitoring. 1

• Complete Heart Block: A potential complication of both surgical and transcatheter closure of perimembranous VSDs. 3

• Exercise Limitations: Patients with significant PAH (peak systolic pulmonary artery pressure >40 mmHg) should limit activity to low-intensity sports. 1