Opening in the interventricular septum causing a left-to-right shunt with a harsh holosystolic murmur at the LLSB.
Also known as: VSD, ventricular septal defect, perimembranous VSD, muscular VSD
Overview
Congenital communication between the right and left ventricles producing a left-to-right shunt. Anatomic subtypes include perimembranous (most common, ~80%), muscular, inlet (AV canal type, often Down syndrome), and outlet (supracristal or doubly committed subarterial, more common in Asian populations and prone to AR from prolapse of an aortic cusp into the defect).
Epidemiology
VSD is the most common congenital heart defect overall (excluding bicuspid aortic valve). Accounts for ~30-40% of CHD. Up to 90% of muscular and small perimembranous VSDs close spontaneously by age 10. Also a recognized complication of acute myocardial infarction (3-5 days post-MI, ventricular septal rupture).
🔒 Free preview limit reached
Keep reading — start your free trial
You've read your 2 free diagnosis previews. Create your free account to unlock the full Ventricular Septal Defect (VSD) outline — plus all 514 diagnoses, 3,500+ board-style questions, flashcards, and an AI tutor. Your 7-day free trial includes everything, and there's no credit card required.
Acquired: ventricular septal rupture after acute MI (anterior or inferior)
Pathophysiology
The magnitude and direction of the shunt depend on defect size and relative resistances of the systemic and pulmonary vascular beds. Restrictive (small) VSDs limit shunt by virtue of high resistance across the defect — produce a loud murmur with little hemodynamic impact. Nonrestrictive (large) VSDs equalize ventricular pressures; shunt magnitude is governed by pulmonary vascular resistance, leading to pulmonary overcirculation, LA and LV volume overload, and eventually pulmonary vascular disease and shunt reversal (Eisenmenger syndrome).
Clinical presentation
Symptoms
Small VSD: asymptomatic, identified by murmur on routine examination
Moderate-to-large VSD in infancy: poor feeding, diaphoresis with feeds, failure to thrive, tachypnea, recurrent pulmonary infections, signs of HF by 4-8 weeks (as PVR falls)
Post-MI VSD: acute cardiogenic shock, pulmonary edema, new harsh murmur
Signs / physical exam
Harsh holosystolic murmur at left lower sternal border, often with palpable thrill
Smaller defects often produce LOUDER murmurs (high pressure gradient, turbulent flow)
Loud P2, narrow split S2 in pulmonary hypertension
Mid-diastolic rumble at the apex from increased mitral inflow in large shunts
Signs of LV volume overload: displaced apical impulse, S3 gallop
Classic findings
Harsh, blowing holosystolic murmur with palpable thrill at the LLSB; intensity inversely related to defect size in many cases.
Differential diagnosis
Mitral regurgitation — Holosystolic murmur at apex radiating to axilla, not LLSB; echo distinguishes
Tricuspid regurgitation — Holosystolic at LLSB but increases with inspiration (Carvallo sign), prominent V wave on JVP
ASD — Wide and fixed split S2, mid-systolic flow murmur, not holosystolic
Hypertrophic cardiomyopathy with LVOT obstruction — Systolic murmur that increases with Valsalva and standing; bisferiens pulse
Pulmonic stenosis — Mid-systolic ejection murmur at ULSB with ejection click
Post-MI ventricular septal rupture — New harsh holosystolic murmur and thrill 3-7 days after MI with hemodynamic deterioration; echo shows defect, often with RV enlargement and tricuspid jet
Diagnostic workup
Labs
Basic labs are typically normal
BNP if HF symptoms
Imaging
Transthoracic echocardiography with color Doppler — diagnostic; defines anatomy, size, shunt direction, chamber size, RV pressure, presence of AR (especially outlet VSD) or AV valve abnormalities
ECG: normal in small VSDs; LA enlargement and LVH with moderate-to-large shunts; biventricular hypertrophy with significant pulmonary HTN; right axis deviation if Eisenmenger
CXR: cardiomegaly, prominent pulmonary vascularity in moderate-to-large shunts; pruning of distal pulmonary arteries in Eisenmenger
Cardiac MRI or CT — useful for complex anatomy or quantifying shunt fraction
Cardiac catheterization with measurement of pulmonary vascular resistance before closure of long-standing large defects
Diagnostic algorithm
VSD Type
Anatomic Location
Frequency
Notable Associations
Perimembranous
Membranous septum, just below aortic valve
~80%
Can develop tricuspid pouch, may close spontaneously
Muscular
Trabecular septum
~5-20%
High spontaneous closure rate; may be multiple ('Swiss cheese')
Inlet (AV canal type)
Inferior septum, beneath AV valves
~5-8%
Down syndrome, AV canal defects
Outlet (supracristal / subarterial)
Just below pulmonary valve
~5% (higher in Asians)
AR from aortic cusp prolapse — close even when small
Anatomic subtypes of VSD with characteristic features and management implications.
Treatment
First-line
Small, restrictive, asymptomatic VSD: observation; spontaneous closure is common in muscular and small perimembranous defects
Hemodynamically significant VSD (HF symptoms, growth failure, pulmonary hypertension reversible): surgical patch closure is the standard, typically in infancy or early childhood
Selected muscular VSDs may be amenable to transcatheter device closure
Medical management of HF in infants while awaiting surgery: diuretics (furosemide), digoxin (selected), ACE inhibitor (captopril, enalapril); high-calorie feeds for growth
Second-line / adjunct
Endocarditis prophylaxis NOT routinely required for unrepaired VSD per current AHA guidelines (indicated only in cyanotic CHD, residual shunt adjacent to prosthetic material, or within 6 months of repair)
Pulmonary vasodilator therapy (sildenafil, bosentan, ambrisentan) for Eisenmenger physiology; closure is contraindicated when PVR is severely fixed
Heart-lung or lung transplantation for severe Eisenmenger syndrome
Post-MI VSD: urgent surgical repair or transcatheter closure with mechanical circulatory support (IABP, Impella, VA-ECMO) for stabilization
Complications
Heart failure from chronic volume overload
Pulmonary hypertension and Eisenmenger syndrome
Aortic regurgitation (especially outlet/supracristal VSDs with aortic cusp prolapse)
Infective endocarditis (small high-velocity jets can damage the tricuspid valve or RV endocardium)
Arrhythmias and conduction defects (especially after septal patch surgery)
Sudden cardiac death (rare)
PANCE pearls
Counterintuitively, smaller VSDs produce louder murmurs due to greater pressure gradient and turbulent flow; Eisenmenger physiology may extinguish the murmur entirely.
Post-MI ventricular septal rupture occurs 3-7 days after MI, more common with first MI, anterior wall involvement, female sex, and elderly — requires urgent surgical or transcatheter repair.
Outlet (supracristal) VSDs are at high risk of progressive AR from aortic cusp prolapse and warrant closure even when small.
Bedside maneuvers: VSD murmur INCREASES with handgrip (afterload increases the shunt); HCM and MVP murmurs increase with Valsalva, while VSD murmur typically decreases or stays the same.
An infant with a VSD typically presents with HF around 4-8 weeks of age as pulmonary vascular resistance falls and the L-to-R shunt magnifies.
References
AHA/ACC 2018 — 2018 AHA/ACC Guideline for the Management of Adults with Congenital Heart Disease (Stout et al., Circulation 2019)
AHA 2021 — Prevention of Viridans Group Streptococcal Infective Endocarditis: AHA Scientific Statement (Wilson et al., Circulation 2021)
ACCF/AHA 2013 — ACCF/AHA Guideline for the Management of ST-Elevation MI (O'Gara et al., JACC 2013)
Practice Cardiovascular questions on FirstPassPA
Turn this outline into retention. 3,500+ board-style questions with an AI tutor that explains every answer — free to start, no card required.
Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants.