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Ventricular Septal Defect (VSD)
VSD is an abnormal communication between the left and right ventricles. It is the most common congenital cardiac anomaly diagnosed at birth, comprising 20–30% of all congenital heart disease.
Anatomy & Classification
The ventricular septum is formed by a muscular ridge growing upward from the apex fusing with a membranous partition growing downward from the endocardial cushions. The basal (membranous) region is the last to develop and accounts for ~90% of VSDs.
VSDs are classified into four types by location:
| Type | Features |
|---|---|
| Perimembranous (paramembranous) | Most common requiring surgery (~80% of surgical cases); involves membranous septum; includes malalignment defects of Tetralogy of Fallot |
| Muscular | Most common overall; surrounded by muscle; can be multiple ("Swiss-cheese" type); located anterior, midventricular, posterior, or apical |
| Inlet (AV canal) | Beneath the tricuspid valve; absent AV canal septum; usually associated with other anomalies |
| Supracristal (outlet) | Conal septum defect; limited by pulmonary valve; above the crista supraventricularis |
Pathophysiology
- Direction and magnitude of shunt depends on defect size and the ratio of pulmonary to systemic vascular resistance (PVR/SVR)
- Large (nonrestrictive) VSDs — diameter ≥ aortic annulus; allow free LV→RV flow; RV pressure equalizes with systemic; high Qp:Qs
- Small (restrictive) VSDs — offer significant resistance; RV pressure normal or minimally elevated; Qp:Qs rarely >1.5
- Chronic large left-to-right shunting → pulmonary hypertension → eventually reversal to right-to-left shunt = Eisenmenger syndrome (occurs in ~10% of VSDs)
- Small/moderate VSDs: jet lesions damage RV endocardium → risk of infective endocarditis
Clinical Presentation
| Defect size | Presentation |
|---|---|
| Small | Asymptomatic; loud grade ≥4 pansystolic murmur at 3rd–4th ICS left sternal border; otherwise normal exam |
| Moderate | Symptoms in childhood; often repaired before adulthood |
| Large | Severe CHF, recurrent respiratory infections, failure to thrive in infancy; in adults → Eisenmenger complex with cyanosis |
Key auscultatory finding: High-frequency, widely radiating holosystolic murmur maximal at the lower left sternal border (3rd–4th ICS) — the loud murmur with otherwise normal exam is a classic diagnostic clue.
Diagnosis
- Echo (transthoracic): First-line — identifies defect, estimates shunt size, assesses LV/RV size and PA pressures
- CXR: Cardiomegaly, pulmonary overcirculation with large defects
- ECG: LV hypertrophy (moderate/large); biventricular hypertrophy with large defects; left atrial enlargement
- Cardiac catheterization: Reserved for pre-surgical assessment in older patients or those with pulmonary hypertension to measure PVR reactivity
Natural History
- ~50% of all native VSDs are small; >50% of small VSDs close spontaneously
- Moderate/large VSDs: close spontaneously in only ~10%
- Closure rate is highest in the first decade of life and inversely related to age:
- 1 month old → ~80% chance of spontaneous closure
- 12 months old → ~25% chance
- Spontaneous closure in adult life is unusual
Treatment
Indications for closure:
- Large defects — repair in infancy (irreversible pulmonary vascular changes can develop in first year of life)
- Moderate defects — Qp:Qs >1.5 with hemodynamic significance
- Eisenmenger complex — contraindicates surgery (prohibitive PVR); manage medically
Surgical repair:
- Cardiopulmonary bypass with moderate hypothermia and cardioplegic arrest
- Right atrial approach preferred for most defects
- Right ventriculotomy for apical muscular defects
- Pulmonary arteriotomy or subpulmonary RV incision for supracristal defects
- Patch closure (synthetic or pericardial) with interrupted or continuous suture technique
Transcatheter closure:
- For perimembranous VSDs, transcatheter device closure is as effective as open surgery and is now the preferred approach in suitable anatomy
Eisenmenger complex management:
- Medical complications of cyanosis (erythrocytosis, paradoxical embolism, hemoptysis)
- Lung or heart-lung transplantation in selected patients
Sources: Schwartz's Principles of Surgery (11th ed.), Goldman-Cecil Medicine, Robbins & Kumar Basic Pathology
infective endocarditis
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Infective Endocarditis (IE)
Definition
Infective endocarditis is a microbial infection of the endocardial surface of the heart — primarily cardiac valves — leading to formation of vegetations composed of fibrin, inflammatory cells, and microorganisms, often with underlying tissue destruction. Prosthetic valves, pacemaker leads, and other intracardiac devices may also be involved.
Classification
| Type | Features |
|---|---|
| Acute IE | Rapidly progressive, destructive; high morbidity/mortality even with treatment; typically S. aureus on healthy valves |
| Subacute IE | Insidious onset; protracted weeks-to-months course; typically viridans streptococci on damaged valves; most recover with antibiotics |
A clear delineation is not always possible — many cases fall along a spectrum.
Epidemiology & Risk Factors
- Incidence: ~3–14 cases per 100,000 persons/year (Western Europe, US)
- ~10,000–20,000 new cases/year in the United States
- Predisposing conditions:
| More Common | Less Common |
|---|---|
| Mitral valve prolapse (with regurgitation) — leading risk factor | Rheumatic heart disease |
| Degenerative valvular disease | Idiopathic hypertrophic subaortic stenosis |
| Injection drug use | Coarctation of the aorta |
| Congenital heart disease (esp. uncorrected VSD) | Complex cyanotic congenital heart disease |
| Previous endocarditis | |
| Prosthetic valves (10–20% of all IE cases) |
- Host risk factors: neutropenia, immunodeficiency, malignancy, diabetes, alcohol use, IV drug use
Microbiology
| Setting | Predominant Organisms |
|---|---|
| Community-acquired (native valve) | S. viridans (50–60%); subacute presentation |
| Healthcare-associated / Hospital | S. aureus — now the #1 cause in high-income countries; acute; attacks healthy valves |
| IV drug users | S. aureus (~70%); tricuspid valve predominance |
| Prosthetic valve (early, <60 days) | S. aureus, coagulase-negative staphylococci |
| Prosthetic valve (late) | Staphylococci (still #1), VGS, S. gallolyticus |
| Culture-negative (~10–15%) | Prior antibiotics, fastidious organisms (Bartonella, Coxiella burnetii, Legionella, fungi) |
HACEK group (oral commensals): Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella
Pathology & Morphology
- Vegetations in IE are friable, bulky, and destructive, containing fibrin, inflammatory cells, and organisms
- Most common sites: Aortic and mitral valves (left-sided); tricuspid in IV drug users
- Ring abscess: Vegetation erodes into underlying myocardium → abscess cavity
- Mycotic aneurysms: Emboli seed arterial walls → local bacterial infection
- Septic emboli → septic infarcts (brain, kidney, spleen, lungs in right-sided IE)
Clinical Features
Symptoms:
- Fever — most consistent sign (may be absent in subacute IE in the elderly)
- Fatigue, weight loss, flu-like illness (subacute); chills, rigors (acute)
- Murmur present in ~90% of left-sided IE
Classic peripheral stigmata:
| Sign | Description |
|---|---|
| Osler nodes | Painful fingertip nodules (immunologic) |
| Janeway lesions | Painless erythematous palm/sole lesions (embolic) |
| Roth spots | Retinal hemorrhages with pale centers |
| Splinter hemorrhages | Nail bed linear hemorrhages |
| Petechiae | From microemboli |
Complications: Glomerulonephritis (immune complex deposition → hematuria, proteinuria, renal failure), arrhythmias (septal extension), heart failure, stroke.
Diagnosis — 2023 Duke Criteria
Definite IE: 2 major criteria OR 1 major + 3 minor OR 5 minor criteria
Possible IE: 1 major + 1 minor OR 3 minor criteria
Possible IE: 1 major + 1 minor OR 3 minor criteria
Major Criteria
A. Microbiologic:
- ≥2 separate blood cultures positive for typical IE organisms (VGS, S. gallolyticus, S. aureus, HACEK, enterococci)
- OR persistently positive blood cultures (≥2 drawn >12 hr apart; or ≥3 of ≥4 drawn ≥1 hr apart)
- OR single positive culture / elevated IgG titer for Coxiella burnetii (Q fever)
- OR positive PCR for C. burnetii, Bartonella, or T. whipplei
B. Imaging:
- Echo/CT: vegetation, valvular perforation/aneurysm, abscess, pseudoaneurysm, intracardiac fistula, new valvular regurgitation, new prosthetic valve dehiscence
- ¹⁸F-FDG PET/CT: abnormal metabolic activity involving native/prosthetic valve or intracardiac device (≥3 months post-implant)
C. Surgical: Direct intraoperative visualization of IE
Minor Criteria
- Predisposing heart condition or IV drug use
- Fever >38°C (>36°C in 2023 update)
- Vascular phenomena: arterial emboli, septic pulmonary infarcts, mycotic aneurysm, Janeway lesions, intracranial hemorrhage, conjunctival hemorrhages
- Immunologic phenomena: glomerulonephritis, Osler nodes, Roth spots, rheumatoid factor
- Microbiologic evidence not meeting major criteria
Investigations
- Blood cultures: Draw ≥3 sets from different sites before antibiotics; critical for diagnosis and guiding therapy
- Echo:
- TTE first in most patients
- TEE when: TTE is non-diagnostic, prosthetic valve, high clinical suspicion, complicated IE (suspected abscess)
- CBC: Normochromic normocytic anemia; leukocytosis (more acute); thrombocytopenia (~10%)
- ESR/CRP: Elevated in ~60%
- Urinalysis: Hematuria, proteinuria (glomerulonephritis)
- CT/MRI: For embolic complications (brain, spleen, kidneys); also CT of chest/abdomen/pelvis
Treatment
Antibiotic Therapy (general principles)
Prolonged IV bactericidal therapy is required. All patients should be managed in an inpatient setting with a multidisciplinary "IE team" (Infectious Disease, Cardiology, Cardiac Surgery).
| Organism | Regimen |
|---|---|
| Penicillin-susceptible streptococci (MIC ≤0.12 μg/mL) | Penicillin G or ceftriaxone 2 g IV daily × 4 weeks (or 2 weeks + gentamicin for uncomplicated NVE) |
| Relatively resistant streptococci (MIC 0.12–0.5 μg/mL) | Penicillin G or ceftriaxone × 4 weeks + gentamicin × 2 weeks |
| MSSA | Nafcillin/oxacillin × 4–6 weeks |
| MRSA | Vancomycin × 6 weeks (target trough 15–20 μg/mL) |
| Enterococci | Ampicillin + gentamicin × 4–6 weeks; or ampicillin + ceftriaxone for aminoglycoside-resistant strains |
| HACEK organisms | Ceftriaxone 2 g IV once daily × 4 weeks |
| Fungi | Amphotericin B ± azole; surgery almost always required |
| Penicillin-allergic patients | Vancomycin (avoid clindamycin due to C. difficile risk; doxycycline as alternative) |
- Native valve IE (NVE): 4-week minimum
- Prosthetic valve IE (PVE): 6-week minimum preferred
Antibiotic Prophylaxis (AHA 2021 Update)
Prophylaxis is recommended only for high-risk patients undergoing invasive dental procedures:
- Prosthetic cardiac valves or valve repair with devices
- Previous IE
- Unrepaired cyanotic congenital heart disease
- Left ventricular assist devices / implantable hearts
Preferred regimen: Amoxicillin 2 g PO 30–60 min before procedure
Penicillin-allergic: Doxycycline (clindamycin no longer recommended)
Key change (2021): 90% of "penicillin-allergic" patients will have negative skin testing — allergy screening before defaulting to alternative agents.
Penicillin-allergic: Doxycycline (clindamycin no longer recommended)
Key change (2021): 90% of "penicillin-allergic" patients will have negative skin testing — allergy screening before defaulting to alternative agents.
Indications for Surgery
| Indication | Class |
|---|---|
| Acute AI or MR with heart failure | I |
| Fungal endocarditis | I |
| Annular/aortic abscess, fistula, valve dehiscence/perforation/rupture | I |
| Persistent infection despite 7–10 days appropriate antibiotics (no noncardiac source) | I |
| Recurrent emboli after appropriate antibiotic therapy | I |
| Gram-negative enteric or antibiotic-resistant organisms with valve dysfunction | I |
| Anterior mitral leaflet vegetation >10 mm OR persistent vegetation after embolization | IIa |
| Vegetation enlarging despite therapy | IIb |
| Prosthetic valve IE — early PVE (<2 months post-op), heart failure, nonstreptococcal/non-HACEK organisms, perivalvular leak/abscess/fistula/new conduction disturbance | I |
There is no survival benefit to delaying surgery >7 days after ischemic stroke when valve replacement is otherwise indicated.
Prognosis
- Untreated IE is universally fatal
- With appropriate antibiotics ± surgery, mortality is substantially reduced but remains significant (~20–30% in-hospital mortality overall)
- Worse prognosis: S. aureus, prosthetic valve IE, Eisenmenger complex, abscess formation, CNS embolization, heart failure
Sources: Robbins & Kumar Basic Pathology, Braunwald's Heart Disease (11th ed.), Goldman-Cecil Medicine, Harrison's Principles of Internal Medicine 22E (2025)
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