Normal Hemodynamic Values
Mastery of normal intracardiac pressures, cardiac output ranges, vascular resistances, and oxygen saturations is the cornerstone of invasive cardiology and the highest-weight domain on the RCIS examination. During diagnostic and interventional cath lab procedures, hemodynamic numbers guide every clinical decision — from diagnosing valvular stenosis and heart failure to calculating shunt fractions and titrating mechanical circulatory support. This authoritative reference guide provides complete hemodynamic tables, mathematical formulas, chamber landmarks, and clinical interpretation rules.
- Normal Intracardiac Pressures Reference Table
- Cardiac Output, Cardiac Index & Stroke Volumes
- Systemic and Pulmonary Vascular Resistance Formulas
- Normal Intracardiac Oxygen Saturations & Oximetry Run
- Intracardiac Shunts: Oximetric Step-Up & Qp:Qs Ratios
- Valve Area Normal Ranges & Critical Severity Thresholds
- High-Yield RCIS Exam Clinical Pearls
- Summary and Key Takeaways
Normal Intracardiac Pressures Reference Table
In the cardiac catheterization laboratory, resting pressures are measured in millimeters of mercury (mmHg) with the patient in the supine position and transducers zeroed at the phlebostatic axis (4th intercostal space, mid-axillary line):
| Cardiac Chamber / Vessel | Systolic (mmHg) | Diastolic (mmHg) | Mean (mmHg) | Waveform Features |
|---|---|---|---|---|
| Right Atrium (RA / CVP) | — | — | 2 – 6 | 'a' wave (atrial systole: 2–7 mmHg), 'v' wave (venous filling: 2–7 mmHg), 'x' and 'y' descents. |
| Right Ventricle (RV) | 15 – 30 | 2 – 8 (RVEDP) | — | Rapid systolic upstroke, early diastolic dip, end-diastolic 'a' wave inflection before QRS. |
| Pulmonary Artery (PA) | 15 – 30 | 8 – 15 | 10 – 20 | Systolic peak, dicrotic notch (pulmonic closure), high diastolic baseline. |
| Pulmonary Capillary Wedge (PCWP) | — | — | 4 – 12 | Reflects Left Atrial Pressure (LAP); 'a' wave (4–13 mmHg), 'v' wave (5–15 mmHg). |
| Left Atrium (Direct LAP) | — | — | 4 – 12 | Identical to PCWP; slightly higher 'v' wave than 'a' wave. |
| Left Ventricle (LV) | 100 – 140 | 3 – 12 (LVEDP) | — | Peak systole, rapid early diastolic dip, LVEDP measured at onset of QRS complex. |
| Central Aorta (AO) | 100 – 140 | 60 – 90 | 70 – 105 (MAP) | Anacrotic limb, peak systole, dicrotic notch (aortic closure), diastolic runoff. |
Cardiac Output, Cardiac Index & Stroke Volumes
Flow measurements determine how effectively the heart delivers oxygenated blood to systemic tissues:
| Hemodynamic Parameter | Formula / Derivation | Normal Adult Range | Clinical Significance |
|---|---|---|---|
| Cardiac Output (CO) | CO = Heart Rate × Stroke Volume | 4.0 – 8.0 L/min | Total volume of blood pumped by the heart per minute. Directly measured by Fick or Thermodilution. |
| Cardiac Index (CI) | CI = CO ÷ Body Surface Area (BSA) | 2.5 – 4.0 L/min/m² | Normalizes cardiac output to patient body size. CI <2.2 L/min/m² defines cardiogenic hypoperfusion / shock. |
| Stroke Volume (SV) | SV = (CO × 1000) ÷ Heart Rate | 60 – 100 mL/beat | Volume of blood ejected by each ventricle during a single contraction (also: EDV − ESV). |
| Stroke Volume Index (SVI) | SVI = SV ÷ BSA | 33 – 47 mL/m² | Normalized stroke volume accounting for body surface area. |
| Ejection Fraction (LVEF) | EF = [(LVEDV − LVESV) ÷ LVEDV] × 100 | 55% – 70% | Percentage of end-diastolic blood volume ejected per beat. <40% indicates heart failure with reduced ejection fraction (HFrEF). |
Systemic and Pulmonary Vascular Resistance Formulas
Vascular resistance quantifies the afterload against which the right and left ventricles must contract:
- Systemic Vascular Resistance (SVR): Measures left ventricular afterload (resistance of systemic arterioles).
$$\text{SVR} = \frac{\text{MAP} - \text{CVP}}{\text{CO}} \times 80$$- Normal SVR: 800 – 1200 dynes·s·cm‾&sup5; (or 10–15 Wood units).
- Low SVR (<800): Distributive / septic shock, anaphylaxis, neurogenic shock, arteriovenous fistulas.
- High SVR (>1400): Cardiogenic shock, hypovolemic shock (compensatory vasoconstriction), severe hypertension.
- Pulmonary Vascular Resistance (PVR): Measures right ventricular afterload (resistance of pulmonary capillary bed).
$$\text{PVR} = \frac{\text{mPAP} - \text{PCWP}}{\text{CO}} \times 80$$- Normal PVR: <250 dynes·s·cm‾&sup5; (or <3.0 Wood units).
- Elevated PVR: Pre-capillary pulmonary arterial hypertension (PAH), pulmonary embolism, chronic hypoxic lung disease (COPD).
- Why multiply by 80? The factor 80 converts pressure-over-flow units ($\text{mmHg} / (\text{L/min})$) into standard CGS resistance units of $\text{dynes}\cdot\text{s}\cdot\text{cm}^{-5}$. Without multiplying by 80, the result is in Wood Units (Hybrid Resistance Units).
Normal Intracardiac Oxygen Saturations & Oximetry Run
During a right-heart catheterization oximetry run, blood samples are drawn from serial chambers to evaluate oxygen delivery and detect intracardiac shunts:
| Sampling Site | Normal O2 Saturation (%) | Key Diagnostic Concept |
|---|---|---|
| Superior Vena Cava (SVC) | 65% – 75% (high) | Drains upper body, head, and arms. |
| Inferior Vena Cava (IVC) | 75% – 80% (low / renal flow) | Higher O2 saturation than SVC due to highly oxygenated renal vein drainage. |
| Mixed Venous (Main PA) | 65% – 75% | True mixed venous (SvO2); complete mixture of SVC, IVC, and coronary sinus blood. |
| Coronary Sinus (CS) | 30% – 40% | Lowest oxygen saturation in the entire human body; reflects intense myocardial oxygen extraction (~60–70% extraction ratio). |
| Left Atrium / PCWP | 95% – 100% | Fully oxygenated blood returning from pulmonary veins. |
| Left Ventricle / Aorta | 95% – 100% | Systemic arterial blood (SaO2). |
Intracardiac Shunts: Oximetric Step-Up & Qp:Qs Ratios
An oximetric step-up occurs when oxygen-rich arterial blood leaks into the right side of the heart across an abnormal communication, raising the venous oxygen saturation above normal thresholds:
- Atrial Septal Defect (ASD): Step-up >7% from SVC/IVC to Right Atrium.
- Ventricular Septal Defect (VSD): Step-up >5% from Right Atrium to Right Ventricle.
- Patent Ductus Arteriosus (PDA): Step-up >5% from Right Ventricle to Pulmonary Artery.
- Quantifying Shunts (Qp:Qs Ratio):
$$\frac{Q_p}{Q_s} = \frac{\text{SaO}_2 - \text{Mixed } S_vO_2}{\text{Pulmonary Vein } O_2 - \text{PA } O_2}$$- Normal Qp:Qs: 1.0 : 1.0 (pulmonary flow equals systemic flow).
- Significant Left-to-Right Shunt: Qp:Qs > 1.5 : 1.0 (indicated for transcatheter or surgical closure).
- Eisenmenger Syndrome (Reversal of Shunt): Severe pulmonary vascular remodeling reverses flow to a Right-to-Left shunt (Qp:Qs < 1.0), causing systemic cyanosis and clubbing.
Valve Area Normal Ranges & Critical Severity Thresholds
In the cath lab, the Gorlin and Hakki formulas are utilized to calculate stenotic valve areas from hemodynamic pull-back tracings:
| Heart Valve | Normal Valve Area | Mild Stenosis | Moderate Stenosis | Severe / Critical Stenosis |
|---|---|---|---|---|
| Aortic Valve (AVA) | 2.5 – 4.0 cm² | 1.5 – 2.0 cm² | 1.0 – 1.5 cm² | ≤1.0 cm² (or indexed ≤0.6 cm²/m²) Critical: ≤0.7 cm² |
| Mitral Valve (MVA) | 4.0 – 6.0 cm² | 1.5 – 2.0 cm² | 1.0 – 1.5 cm² | ≤1.5 cm² Very Severe: ≤1.0 cm² |
| Tricuspid Valve (TVA) | 7.0 – 9.0 cm² | >1.5 cm² | 1.0 – 1.5 cm² | ≤1.0 cm² (mean gradient ≥5 mmHg) |
| Pulmonic Valve (PVA) | 3.5 – 4.5 cm² | Peak grad <36 mmHg | Peak grad 36–64 mmHg | Peak grad >64 mmHg |
The Hakki Formula (Quick Bedside AVA): For heart rates between 60–100 bpm, the Hakki equation provides a rapid approximation: $$\text{AVA} = \frac{\text{Cardiac Output (L/min)}}{\sqrt{\text{Mean Systolic Gradient (mmHg)}}}$$
High-Yield RCIS Exam Clinical Pearls
- Lowest Oxygen Saturation: The Coronary Sinus (30–40%) has the lowest oxygen saturation in the entire body due to maximal myocardial extraction.
- CVP Normal Range: Mean 2–6 mmHg. Values >12 mmHg suggest right ventricular failure, volume overload, or tricuspid regurgitation.
- PCWP Normal Range: Mean 4–12 mmHg. Values >18 mmHg indicate left-sided pulmonary venous congestion; >25 mmHg indicates pulmonary alveolar edema.
- Fick Principle: Oxygen consumption (VO2) divided by arteriovenous oxygen content difference is the gold standard for cardiac output in severe arrhythmias or tricuspid regurgitation.
- Cardiogenic Shock CI Threshold: A Cardiac Index <2.2 L/min/m² with elevated PCWP >18 mmHg defines cardiogenic shock (Diamond-Forrester Warm/Wet vs Cold/Wet subsets).
Summary and Key Takeaways
- Knowing resting intracardiac pressures cold is required for all RCIS calculations and clinical troubleshooting.
- Cardiac output (4–8 L/min) and cardiac index (2.5–4.0 L/min/m²) reflect overall systemic perfusion.
- SVR (800–1200 dynes·s·cm⁻⁵) quantifies systemic afterload; PVR (<250 dynes·s·cm⁻⁵) reflects pulmonary afterload.
- Oximetry runs detect intracardiac shunts via oxygen step-ups; Qp:Qs >1.5 indicates significant Left-to-Right shunting.
- Severe aortic stenosis is defined by an AVA ≤1.0 cm²; severe mitral stenosis is defined by an MVA ≤1.5 cm².
Lock in the normal values
Free hemodynamics questions with worked explanations.
Practise Hemodynamics →Frequently asked questions
What are the normal pressures in the right side of the heart?
Normal right-sided pressures are: Right Atrium mean 2–6 mmHg; Right Ventricle 15–30 / 2–8 mmHg; Pulmonary Artery 15–30 / 8–15 mmHg (mean 10–20 mmHg); Pulmonary Capillary Wedge Pressure (PCWP) mean 4–12 mmHg.
What are the normal pressures in the left side of the heart?
Normal left-sided pressures are: Left Ventricle 100–140 / 3–12 mmHg (LVEDP); Central Aorta 100–140 / 60–90 mmHg (mean 70–105 mmHg); Left Atrium mean 4–12 mmHg.
What is a normal systemic vascular resistance (SVR)?
Normal Systemic Vascular Resistance (SVR) is 800 to 1200 dynes·s·cm⁻⁵. In Wood units, this is approximately 10 to 15 Wood units (calculated without multiplying by 80).
What is the lowest oxygen saturation in the human body?
The coronary sinus has the lowest oxygen saturation in the human body, typically 30% to 40%. This occurs because the contracting myocardium extracts 60% to 75% of delivered oxygen, far exceeding the extraction rate of other tissues.
What defines severe aortic stenosis on hemodynamic catheterization?
Severe aortic stenosis is defined by an Aortic Valve Area (AVA) of 1.0 cm² or less (or indexed AVA ≤0.6 cm²/m²), typically accompanied by a mean transvalvular systolic gradient exceeding 40 mmHg in patients with normal cardiac output.
What is the normal cardiac index (CI)?
The normal cardiac index is 2.5 to 4.0 L/min/m². A cardiac index below 2.2 L/min/m² indicates systemic hypoperfusion, while a CI below 1.8 L/min/m² indicates severe cardiogenic shock requiring inotropic or mechanical circulatory support.
What is an oximetric step-up?
An oximetric step-up is an unexpected increase in blood oxygen saturation found in the right heart during a catheterization oximetry run. It indicates a Left-to-Right intracardiac shunt (such as an ASD, VSD, or PDA) dumping oxygen-rich arterial blood into the venous circulation.
How do you calculate Mean Arterial Pressure (MAP)?
Mean Arterial Pressure can be calculated as: MAP = Diastolic BP + 1/3 (Systolic BP − Diastolic BP), or MAP = (Systolic BP + 2 × Diastolic BP) ÷ 3. In the cath lab, the electronic integrator computes the true area under the arterial curve.
What does a high Pulmonary Capillary Wedge Pressure (PCWP) indicate?
An elevated PCWP (>12 mmHg) indicates elevated left atrial pressure, which is caused by left ventricular systolic or diastolic heart failure, mitral valve disease (stenosis or regurgitation), volume overload, or constrictive pericarditis.
Sources & further reading
- Cardiovascular Credentialing International (CCI)
- American College of Cardiology
- American Heart Association
- MedlinePlus (U.S. National Library of Medicine)
External links are provided for reference; always confirm current details with the official source.