Qp Qs
Normal cardiac anatomy with balanced flows
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Normal (No Shunt)
Normal cardiac anatomy with balanced flows
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Small ASD (Qp/Qs 1.5)
Small left-to-right shunt
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Moderate VSD (Qp/Qs 2.0)
Moderate left-to-right shunt requiring intervention
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Large Shunt (Qp/Qs >2.5)
Significant shunting likely requiring closure
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Eisenmenger Syndrome
Right-to-left shunting with cyanosis
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Sample Scenarios
Normal (No Shunt)
Normal cardiac anatomy with balanced flows
Small ASD (Qp/Qs 1.5)
Small left-to-right shunt
Moderate VSD (Qp/Qs 2.0)
Moderate left-to-right shunt requiring intervention
Large Shunt (Qp/Qs >2.5)
Significant shunting likely requiring closure
Eisenmenger Syndrome
Right-to-left shunting with cyanosis
Enter Oxygen Saturations
Saturations
Additional
For informational purposes only — not medical advice. Consult a healthcare professional before acting on results.
🏥 Health Facts
— WHO
— CDC
Understanding Qp/Qs
The Qp/Qs ratio compares pulmonary (Qp) to systemic (Qs) blood flow. In normal physiology, these are equal (1:1). Intracardiac shunts cause an imbalance, with left-to-right shunts increasing Qp/Qs and right-to-left shunts decreasing it.
Normal
1:1
Moderate L→R
1.5-2:1
Large L→R
≥2:1
The Fick Principle for Shunt Calculation
- • Principle: Blood flow = Oxygen consumption / Arteriovenous O2 difference
- • Qp: Pulmonary blood flow measured from pulmonary vein - PA saturation
- • Qs: Systemic blood flow measured from aorta - mixed venous saturation
- • Ratio: Qp/Qs compares the two to identify shunting
- • Assumption: Oxygen consumption is constant
Normal Oxygen Saturations by Location
| Location | Normal Saturation | Clinical Significance |
|---|---|---|
| SVC | 65-75% | Upper body venous return |
| IVC | 75-85% | Lower body return (higher due to kidneys) |
| RA (mixed) | 70-75% | Right atrial mixed venous |
| RV | 70-75% | Should match RA |
| PA | 70-75% | True mixed venous (gold standard) |
| Pulmonary veins | 95-100% | Oxygenated blood |
| Aorta/LA | 95-100% | Systemic arterial blood |
Detecting an Oxygen Step-Up
- • Atrial level: Step-up >7-9% suggests ASD/PAPVR
- • Ventricular level: Step-up >5-7% suggests VSD
- • Great vessel level: Step-up >5% suggests PDA
- • Method: Compare saturation to expected for that level
- • Key: Left-to-right shunt causes oxygen step-up on right side
Atrial Septal Defect (ASD) Assessment
Types of ASD
- • Secundum (70%): Central fossa ovalis
- • Primum (20%): Adjacent to AV valves
- • Sinus venosus (10%): SVC or IVC junction
- • Coronary sinus: Rare
Closure Indications
- • Qp/Qs ≥1.5:1 with RV dilation
- • Symptoms (dyspnea, arrhythmia)
- • Paradoxical embolism history
- • No severe pulmonary hypertension
Ventricular Septal Defect (VSD) Assessment
- • Perimembranous (80%): Most common, adjacent to aortic valve
- • Muscular: May be multiple (Swiss cheese)
- • Outlet: Below pulmonary valve, can cause aortic regurgitation
- • Inlet: Associated with AVSD
- • Closure threshold: Generally Qp/Qs >2.0 or symptoms
Patent Ductus Arteriosus (PDA) Assessment
- • Location: Connection between aorta and PA
- • Saturation step-up: In pulmonary artery
- • Differential cyanosis: Upper extremities pink, lower cyanotic (Eisenmenger PDA)
- • Symptoms: Continuous murmur, wide pulse pressure
- • Closure: Usually indicated regardless of Qp/Qs (endarteritis risk)
Eisenmenger Syndrome
- • Definition: Reversal of shunt to right-to-left due to pulmonary hypertension
- • Qp/Qs: Becomes <1.0 (sometimes bidirectional)
- • Cyanosis: Present due to right-to-left shunting
- • Contraindication: Closure typically contraindicated (worsens RV failure)
- • Management: Pulmonary vasodilators, avoid pregnancy, transplant consideration
Pulmonary Vascular Resistance (PVR)
- • Formula: PVR = (Mean PAP - PCWP) / Qp
- • Normal: <3 Wood units
- • Elevated: >6 Wood units concerning
- • Operability: PVR/SVR ratio, vasoreactivity testing
- • Irreversible: High PVR may contraindicate closure
Operability Assessment
- • PVR <5 Wood units: Generally operable
- • PVR 5-8 Wood units: Gray zone - vasoreactivity testing
- • PVR >8 Wood units: High risk - usually inoperable
- • PVR/SVR <0.33: Favorable
- • Vasodilator challenge: May unmask reversibility
Catheterization Technique
- • Oxygen run: Saturations from SVC, IVC, RA, RV, PA, pulm veins, aorta
- • Multiple samples: Ensure steady state, avoid contamination
- • SVC vs PA for SvO2: PA preferred but SVC acceptable
- • Pulmonary vein sampling: Difficult, often assume 98%
- • Avoid supplemental O2: Can alter saturations
Clinical Pearls
- • IVC sat higher than SVC: Renal blood has high sat (oxygenated but low extraction)
- • Multiple defects: May have shunting at multiple levels
- • Variability: Saturations vary with respiration, anxiety, sedation
- • Streaming: Blood may not fully mix - sample multiple locations
- • Echo correlation: Always correlate with echocardiography
Non-invasive Qp/Qs Assessment
- • Echocardiography: LVOT/RVOT stroke volumes can estimate Qp/Qs
- • MRI: Phase-contrast MRI measures flow in aorta and PA
- • Limitations: Less accurate than catheterization in complex cases
- • Indication: May suffice if cath not warranted
- • Agreement: Generally good correlation with invasive measurement
Clinical Scenario Examples
Scenario 1: Small Secundum ASD
SaO2 98%, SvO2 72%, RA sat 78% (step-up), PA sat 78%. Qp/Qs 1.3:1. Small shunt, monitoring appropriate if asymptomatic.
Scenario 2: Large VSD
SaO2 96%, SvO2 68%, RV sat 85% (step-up), PA sat 85%. Qp/Qs 2.3:1. Large shunt with RV volume overload. Closure indicated.
Scenario 3: Eisenmenger Syndrome
SaO2 80%, SvO2 55%, PA sat 55%. Qp/Qs 0.7:1. Right-to-left shunt with cyanosis. Severe PAH, closure contraindicated.
Key Formulas
- Qp/Qs: (SaO2 - SvO2) / (PvO2 - PA sat)
- Shunt fraction: Qs / Qp (for L→R)
- Effective pulm flow: Qp × (SvO2 / SaO2)
- PVR: (Mean PAP - PCWP) / Qp
- SVR: (Mean AoP - RAP) / Qs
Qp/Qs Calculator Summary
Normal
1:1
Moderate L→R
1.5-2:1
Large L→R
>2:1
R→L (Eisenmenger)
<1:1
Documentation Guide
- • Saturations: All levels from SVC to aorta
- • Step-up location: Where is the increase detected?
- • Qp/Qs: Calculated ratio with interpretation
- • Pressures: RA, RV, PA, PCWP, aorta
- • PVR: Include vasoreactivity if performed
Key References
AHA/ACC Guidelines
Guidelines for the Management of Adults with Congenital Heart Disease. JACC 2018.
ESC Guidelines
ESC Guidelines for the management of grown-up congenital heart disease. Eur Heart J 2020.
Grossman's Cardiac Catheterization
Standard reference for hemodynamic assessment techniques.
Memory Aids
- • "1.5 is the cutoff" - Consider intervention for Qp/Qs ≥1.5
- • "Step-up = L→R" - Higher sat on right = left-to-right shunt
- • "Step-down = R→L" - Lower sat on left = right-to-left shunt
- • "Eisenmenger = reversed" - Long-standing L→R becomes R→L
Key Takeaways
- • Qp/Qs quantifies the magnitude of intracardiac shunting
- • Qp/Qs ≥1.5 with RV dilation typically warrants intervention
- • PVR assessment crucial for operability determination
- • Eisenmenger syndrome (Qp/Qs <1.0) generally contraindicates closure
- • Echo and MRI can provide non-invasive estimates
- • Oxygen step-up localizes the shunt level
Important Disclaimer
This calculator provides estimates for educational purposes. Accurate Qp/Qs determination requires cardiac catheterization with proper oxygen saturation sampling technique. Clinical decisions regarding shunt closure should be made by specialists in adult congenital heart disease considering the complete hemodynamic and clinical picture.
Transcatheter vs Surgical Closure
Transcatheter Closure
- • Secundum ASD: First-line if anatomy suitable
- • Device closure (Amplatzer, Gore, etc.)
- • Requires adequate rims for device
- • Lower procedural risk than surgery
- • Not suitable for primum or sinus venosus ASD
Surgical Closure
- • Primum ASD, sinus venosus ASD
- • Complex anatomy unsuitable for device
- • VSD closure often surgical
- • Concomitant procedures (valve repair)
- • Patch or primary closure
Atrioventricular Septal Defect (AVSD)
- • Complete AVSD: Both ASD and VSD with common AV valve
- • Partial AVSD: Primum ASD with cleft mitral valve
- • Association: Common in Down syndrome
- • Shunt: May be at both atrial and ventricular level
- • Timing: Early surgical repair often needed
Anomalous Pulmonary Venous Return
- • PAPVR: Partial - some veins drain to right side
- • TAPVR: Total - all pulmonary veins drain to right side
- • Step-up: May see step-up in SVC or RA depending on drainage
- • Qp/Qs: Elevated similar to ASD
- • Associated: Often with sinus venosus ASD
Right Heart Volume Overload
- • Mechanism: Excess pulmonary blood flow from L→R shunt
- • RV dilation: Develops with significant shunting
- • TR: May develop tricuspid regurgitation
- • Arrhythmias: Atrial arrhythmias common, especially older patients
- • Reversibility: RV size often normalizes after closure
Pulmonary Hypertension in CHD
- • Mechanism: Chronic high pulmonary flow causes vascular remodeling
- • Timeline: Can develop years after shunt appears
- • Progression: VSD/PDA tend to develop PAH faster than ASD
- • Assessment: Mean PAP, PVR, PVR/SVR ratio
- • Operability: Key question before closure
Vasoreactivity Testing
- • Agents: iNO (inhaled nitric oxide), O2, adenosine, epoprostenol
- • Positive response: ≥10 mmHg drop in mPAP to ≤40 mmHg
- • Purpose: Assess reversibility of PAH
- • Favorable: Drop in PVR with vasodilator suggests operability
- • Application: Used when PVR borderline (5-8 Wood units)
Oxygen Consumption in Fick Calculation
- • Measured VO2: Gold standard but often not available
- • Assumed VO2: ~125 mL/min/m² (seated) to 110 (supine)
- • LaFarge equations: Based on age, sex, heart rate
- • Limitation: Assumed VO2 can introduce error
- • Sedation effect: May lower VO2
Bidirectional Shunting
- • Mechanism: Shunting varies with cardiac cycle or respiration
- • With elevated PVR: R→L during systole, L→R during diastole
- • Qp/Qs: May appear near 1.0 but not truly balanced
- • Desaturation: Can have cyanosis despite "balanced" Qp/Qs
- • Assessment: May need detailed saturation runs
Adults with Congenital Heart Disease (ACHD)
- • Growing population: Survivors of childhood surgery
- • New diagnosis: ASD sometimes found incidentally in adults
- • Arrhythmias: Common complication, especially with ASD
- • Pregnancy: Higher risk if significant shunt or PAH
- • Specialist care: ACHD center recommended
Pregnancy Considerations
- • Small ASD: Usually well tolerated
- • Large shunt: Risk of heart failure, arrhythmia
- • Eisenmenger: Pregnancy contraindicated (30-50% mortality)
- • Paradoxical embolism: Risk with R→L component
- • Pre-conception: Closure recommended before pregnancy if indicated
Exercise and Shunts
- • L→R shunt: Exercise capacity often preserved until late
- • R→L shunt: Desaturation with exercise (increased R→L flow)
- • Exercise testing: May unmask symptoms or desaturation
- • Post-closure: Exercise capacity typically improves
- • Restrictions: Usually none with small repaired defects
Arrhythmia Management
- • Atrial fibrillation: Common with ASD, especially older patients
- • Pre-closure: AF may persist even after closure
- • Rate vs rhythm: Control strategies as per guidelines
- • Anticoagulation: Consider for AF, also paradoxical embolism risk
- • Ablation: May be combined with closure procedure
Post-Closure Follow-up
- • Echo: Assess device position, residual shunt
- • RV remodeling: Size should normalize over months
- • Antiplatelet: Usually aspirin ± clopidogrel for 6 months (device)
- • Endocarditis prophylaxis: First 6 months after device closure
- • Long-term: Annual ACHD follow-up
Common Questions
What Qp/Qs requires closure?
Generally Qp/Qs ≥1.5 with RV dilation in ASD, or ≥2.0 for VSD. Symptomatic patients may warrant closure at lower ratios.
Can a small shunt become larger?
ASDs rarely get larger but shunt magnitude can increase with age as LV compliance decreases. VSDs often get smaller (partial muscular closure).
Why does Qp/Qs reverse in Eisenmenger?
Chronic pulmonary overcirculation causes pulmonary vascular remodeling and PAH. When PVR exceeds SVR, flow reverses (R→L).
Step-by-Step Qp/Qs Interpretation
- Review oxygen saturations from all sampling locations
- Identify any step-up (increase) in saturations
- Determine level of step-up (atrial, ventricular, great vessel)
- Calculate Qp/Qs using appropriate saturations
- Assess hemodynamic pressures (RA, PA, PCWP)
- Calculate PVR if elevated PA pressures
- Correlate with echocardiographic findings
- Determine if intervention indicated
Final Clinical Summary
The Qp/Qs ratio is fundamental for quantifying intracardiac shunts. A ratio ≥1.5 with evidence of right heart volume overload typically indicates need for intervention in ASD. VSD closure is often considered at higher ratios (≥2.0) or with symptoms. PVR assessment is critical when PAH is present to determine operability. Eisenmenger syndrome (Qp/Qs <1.0 with cyanosis) generally contraindicates closure.
Normal
Qp/Qs = 1.0
Consider closure
Qp/Qs ≥1.5
Large shunt
Qp/Qs ≥2.0
Eisenmenger
Qp/Qs <1.0
Additional Resources
- • Adult Congenital Heart Association - achaheart.org
- • American Heart Association - heart.org
- • ESC ACHD Guidelines - escardio.org
- • Congenital Heart Public Health Consortium
- • ACHD Catheter Laboratory Protocols
Quick Reference Card
- • Qp/Qs formula: (SaO2 - SvO2) / (PvO2 - PA sat)
- • Normal: Qp/Qs = 1.0
- • Significant L→R: Qp/Qs ≥1.5
- • Large shunt: Qp/Qs ≥2.0
- • R→L (Eisenmenger): Qp/Qs <1.0
- • Step-up levels: Atrial >7-9%, Ventricular >5-7%, Great vessel >5%
- • PVR normal: <3 Wood units
PDA Closure Considerations
- • Indications: All PDAs generally warrant closure (endarteritis risk)
- • Device closure: Most common approach for small-moderate PDA
- • Surgical: Large or complex anatomy
- • Calcified PDA: Challenge in older adults
- • Silent PDA: Even small PDAs are usually closed if found
Non-invasive Shunt Detection
Echocardiography
- • Color Doppler across defect
- • Bubble study for R→L
- • Chamber sizes (RV dilation)
- • Qp/Qs from stroke volumes
- • TR velocity for PAP estimate
Cardiac MRI
- • Phase-contrast flow in Ao and PA
- • Direct Qp/Qs measurement
- • Ventricular volumes
- • Visualization of anatomy
- • Gold standard for quantification
Hemodynamic Waveform Clues
- • RA "V" wave: May suggest tricuspid regurgitation from RV volume overload
- • PA pressure: Elevated in large shunts or PAH development
- • PCWP: Often normal unless LV dysfunction
- • Step-up in saturation: Most reliable finding for L→R shunt
- • Aortic runoff: Wide pulse pressure with PDA
Shunts in the Elderly
- • ASD diagnosis: Sometimes first diagnosed in 60s-70s
- • Increasing shunt: LV stiffness increases L→R flow
- • Symptoms: Dyspnea, exercise intolerance, AF
- • Closure benefit: Often beneficial even in older patients
- • Considerations: Comorbidities, procedural risk assessment
Pediatric Shunt Assessment
- • Spontaneous closure: Small VSDs often close spontaneously
- • Timing: Large VSD repair often in infancy to prevent PAH
- • ASD closure: Usually deferred to age 3-5 unless symptomatic
- • Growth: Must account for patient growth in sizing
- • Sedation: Often required for catheterization
Complications of Untreated Shunts
- • Right heart failure: From chronic volume overload
- • Pulmonary hypertension: Can progress to Eisenmenger
- • Atrial arrhythmias: AF, flutter common in ASD
- • Paradoxical embolism: Stroke through R→L shunt
- • Endocarditis: Risk especially with VSD, PDA
Catheter-Based Closure Devices
- • ASD devices: Amplatzer Septal Occluder, Gore CARDIOFORM
- • PFO devices: Multiple approved devices available
- • VSD devices: Limited use, more complex
- • PDA devices: Coils, Amplatzer Duct Occluder
- • Rim requirements: Need adequate tissue rims for device anchoring
Device Closure Complications
- • Embolization: Rare with proper sizing
- • Erosion: Rare but serious (ASD devices)
- • Residual shunt: May persist initially, often closes over time
- • Arrhythmia: New onset AF or heart block
- • Thrombosis: Reason for antiplatelet therapy
Surgical Closure Techniques
- • Primary closure: Direct suture for small defects
- • Patch closure: Pericardium or synthetic patch
- • Minimally invasive: Mini-thoracotomy approaches
- • CPB: Usually requires cardiopulmonary bypass
- • Concomitant procedures: Valve repair, Maze procedure
Outcome Assessment After Closure
- • Qp/Qs: Should normalize (1.0)
- • RV size: Remodeling over weeks to months
- • PA pressure: May decrease if not fixed PAH
- • Symptoms: Improvement in exercise tolerance
- • Arrhythmias: AF may persist in older patients
Final Memory Aids
- • "Step-up = Left-to-Right" - Oxygen increase on right side
- • "1.5 for ASD, 2.0 for VSD" - Typical closure thresholds
- • "Eisenmenger = can't close" - R→L from irreversible PAH
- • "PDA always close" - Endarteritis risk regardless of Qp/Qs
- • "Check PVR before closing" - Operability assessment
Clinical Decision Algorithm
Yes → Consider closure
No → Monitor unless symptomatic
Yes → Calculate PVR
No → Proceed with closure evaluation
Yes → Likely operable
No → Vasoreactivity testing
Yes → Eisenmenger - closure contraindicated
Shunt Evaluation Checklist
- • ☐ Complete oxygen saturation run
- • ☐ Identify step-up level and magnitude
- • ☐ Calculate Qp/Qs
- • ☐ Record hemodynamic pressures
- • ☐ Calculate PVR if PA pressure elevated
- • ☐ Consider vasoreactivity testing if PVR borderline
- • ☐ Correlate with echocardiography
- • ☐ Assess symptoms and functional capacity
- • ☐ Determine closure indication and approach
Final Important Note
This calculator provides educational estimates for Qp/Qs calculation. Clinical management of intracardiac shunts requires comprehensive evaluation including catheterization, imaging, and clinical assessment by specialists in adult congenital heart disease. Decisions regarding shunt closure should be made at experienced ACHD centers.
Anticoagulation Considerations
- • Post-device: Aspirin ± clopidogrel for 6 months typically
- • Atrial fibrillation: Anticoagulation per standard AF guidelines
- • Paradoxical embolism: Consider anticoagulation if demonstrated
- • Eisenmenger: Complex decision - bleeding vs thrombosis risk
- • Prosthetic materials: Device endothelialization over months
Genetic Associations
- • Down syndrome: AVSD, VSD, ASD common
- • Holt-Oram: ASD with upper limb abnormalities
- • Noonan syndrome: ASD, pulmonic stenosis
- • Familial ASD: NKX2-5, TBX5 mutations
- • Genetic counseling: Consider for family members
Imaging Modalities Overview
| Modality | Strengths | Limitations |
|---|---|---|
| TTE | Available, cheap, no radiation | Limited windows in some patients |
| TEE | Better visualization, guides intervention | Invasive, requires sedation |
| Cardiac MRI | Gold standard Qp/Qs, no radiation | Cost, availability, devices |
| Catheterization | Definitive hemodynamics, intervention | Invasive, radiation |
Natural History of Shunts
- • Small ASD: May remain stable for decades, some close
- • Large ASD: Progressive RV dilation, AF, eventual RV failure
- • VSD: Small may close spontaneously; large need early repair
- • PDA: Continuous murmur, heart failure if large
- • Timeline to Eisenmenger: Faster with VSD/PDA than ASD
Quality of Life After Repair
- • Exercise capacity: Often improves after closure
- • Functional class: Most patients improve NYHA class
- • Arrhythmia: Risk may persist, especially if pre-existing AF
- • Work/Activity: Usually unrestricted after successful closure
- • Long-term: Life expectancy approaches normal if repaired early
ACHD Centers of Excellence
- • Multidisciplinary team: Cardiologists, surgeons, nurses, psychologists
- • Volume: Higher volume centers have better outcomes
- • Expertise: Specialized training in ACHD
- • Imaging: Advanced imaging capabilities
- • Interventional: Catheter-based closure expertise
Long-term Surveillance
- • Small unrepaired: Annual or biennial echo follow-up
- • Post-device: Echo at 1, 6, 12 months, then annually
- • Post-surgical: Annual ACHD follow-up
- • Residual shunt: More frequent monitoring
- • Arrhythmia surveillance: ECG, Holter as indicated
Summary Reference Table
- • Qp/Qs = 1.0: Normal balanced flows
- • Qp/Qs 1.0-1.5: Small L→R shunt (usually observe)
- • Qp/Qs 1.5-2.0: Moderate L→R (consider closure if RV dilation)
- • Qp/Qs ≥2.0: Large L→R (closure usually indicated)
- • Qp/Qs <1.0: R→L shunt (Eisenmenger if with cyanosis)
- • PVR normal: <3 Wood units
- • PVR concern: >5-6 Wood units
Final Clinical Reminder
The Qp/Qs ratio is a fundamental tool for quantifying intracardiac shunts. Remember that the clinical decision to close a shunt depends not only on Qp/Qs but also on symptoms, RV size, PA pressures, PVR, anatomy, and patient factors. Complex cases should be managed at specialized ACHD centers with multidisciplinary expertise.
Quick Reference Values
- • Normal Qp/Qs: 1.0
- • ASD closure threshold: ≥1.5 with RV dilation
- • VSD closure threshold: ≥2.0 or symptomatic
- • PDA: Usually close all (endarteritis risk)
- • Atrial step-up: ≥7-9% suggests ASD
- • Ventricular step-up: ≥5-7% suggests VSD
- • PVR operability: <5 Wood units favorable
Interventional Considerations
- • Balloon sizing: Used to determine ASD device size
- • TEE guidance: Essential for device positioning
- • ICE: Intracardiac echo alternative to TEE
- • Test occlusion: May assess hemodynamic response before permanent closure
- • Hybrid approach: Combination of surgical and catheter techniques
Emergency Considerations
- • Device embolization: Retrieval procedure or surgical removal
- • Cardiac erosion: Rare but life-threatening, may need surgery
- • Heart block: May occur with VSD closure near conduction system
- • Eisenmenger crisis: Supportive care, avoid closure
- • Paradoxical embolism: Anticoagulation, consider closure
Documentation Requirements
- • Complete saturation run: All sampling locations
- • Calculated Qp/Qs: With formula and inputs
- • Hemodynamic data: All pressures, cardiac output
- • PVR calculation: If PA pressure elevated
- • Anatomic description: Defect size, location, rims
- • Interpretation: Clinical significance and recommendations
Qp/Qs Final Summary
Formula
(SaO2-SvO2)/(PvO2-PA)
Normal
1.0
Significant
≥1.5
Eisenmenger
<1.0
Final Disclaimer
This educational calculator estimates Qp/Qs from entered oxygen saturation values. Actual clinical assessment requires proper cardiac catheterization technique with appropriate sampling. Management decisions should be made by specialists in adult congenital heart disease at experienced centers, considering the complete clinical picture including symptoms, imaging, and hemodynamic data.
Medications in ACHD with Shunts
- • Diuretics: For heart failure symptoms from volume overload
- • Anticoagulation: AF, prosthetic materials, paradoxical embolism
- • Beta-blockers: Rate control, arrhythmia management
- • PAH therapy: In Eisenmenger (bosentan, sildenafil)
- • Antiarrhythmics: For atrial fibrillation/flutter
Endocarditis Prophylaxis
- • Unrepaired cyanotic: Prophylaxis recommended
- • First 6 months post-device: Prophylaxis recommended
- • Residual defect adjacent to device: Prophylaxis recommended
- • Repaired without residua: Prophylaxis not routinely needed after 6 months
- • General guidance: Follow AHA endocarditis prevention guidelines
Quick Calculator Reference
- • Input SaO2: Systemic arterial O2 saturation (aorta/femoral artery)
- • Input SvO2: Mixed venous saturation (SVC or PA)
- • Input PvO2: Pulmonary venous saturation (usually ~98%)
- • Output Qp/Qs: Ratio of pulmonary to systemic blood flow
- • Interpretation: >1 = L→R; <1 = R→L; ~1 = balanced
Final Reference Values
- • Normal SVC sat: 65-75%
- • Normal IVC sat: 75-85%
- • Normal RA sat: 70-75%
- • Normal PA sat: 70-75%
- • Normal PV sat: 95-100%
- • Normal Qp/Qs: 1.0
- • PVR normal: <3 Wood units
- • Step-up threshold (atrial): ≥7-9%
- • Step-up threshold (ventricular): ≥5-7%
- • Closure threshold (ASD): Qp/Qs ≥1.5 with RV dilation
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