PASP Calculation on Echocardiography

Pulmonary Artery Systolic Pressure (PASP) Calculation on Echocardiography

Introduction

Pulmonary artery systolic pressure (PASP) is a key echocardiographic parameter used to assess pulmonary hemodynamics and screen for pulmonary hypertension. It is non-invasively estimated using Doppler interrogation of tricuspid regurgitation (TR).

---

Principle

PASP is derived from the pressure gradient between the right ventricle (RV) and right atrium (RA) during systole, using the modified Bernoulli equation.

\Delta P = 4V^2

Where:

ΔP = pressure gradient between RV and RA

V = peak velocity of tricuspid regurgitation (m/s)

---

PASP Formula

PASP = 4V^2 + RAP

Where:

PASP = Pulmonary artery systolic pressure

V = Peak TR velocity (m/s)

RAP = Right atrial pressure (mmHg)

---

Step-by-Step Calculation

1. Measure TR Velocity

Use continuous-wave Doppler across tricuspid valve

Align Doppler beam parallel to TR jet

Record peak TR velocity (V)

2. Calculate Pressure Gradient

Apply Bernoulli equation: ΔP = 4V²

3. Estimate Right Atrial Pressure (RAP)

Based on IVC size and collapsibility:

IVC Diameter Collapse with Sniff RAP

< 2.1 cm > 50% 3 mmHg

> 2.1 cm < 50% 15 mmHg

Intermediate Variable 8 mmHg

4. Add RAP to Gradient

PASP = 4V² + RAP

---

Example

TR velocity = 3 m/s

RAP = 10 mmHg

PASP = 4 × (3²) + 10

PASP = 36 + 10 = 46 mmHg

---

Normal Values

PASP Interpretation

≤ 30–35 mmHg Normal

36–50 mmHg Mild elevation

51–70 mmHg Moderate elevation

> 70 mmHg Severe elevation

---

Important Assumptions

No significant RV outflow obstruction

No pulmonic stenosis

Accurate TR jet alignment

---

Pitfalls and Limitations

1. Poor TR Signal

Leads to underestimation

2. Incorrect RAP Estimation

Common source of error

3. Severe TR

May underestimate PASP due to rapid pressure equalization

4. Suboptimal Doppler Angle

Underestimates velocity → underestimates PASP

5. Mechanical Ventilation

Alters IVC dynamics → inaccurate RAP

---

Clinical Significance

Screening tool for pulmonary hypertension

Guides further evaluation (e.g., right heart catheterization)

Useful in valvular heart disease, congenital heart disease, and heart failure

---

Pro Tips

Always search multiple windows (apical, parasternal, subcostal) for best TR signal

Use highest recorded TR velocity

Integrate with other echo findings (RV size, septal flattening, PA dilation)

---

Conclusion

PASP estimation on echocardiography is a simple, widely used, and valuable non-invasive method. Accuracy depends on proper Doppler technique and careful RAP estimation, and results should always be interpreted in clinical context.

Comments

𝘼𝙣𝙩𝙞𝙘𝙤𝙖𝙜𝙪𝙡𝙖𝙩𝙞𝙤𝙣 𝘼𝙛𝙩𝙚𝙧 𝙎𝙩𝙧𝙤𝙠𝙚

𝘼𝙣𝙩𝙞𝙘𝙤𝙖𝙜𝙪𝙡𝙖𝙩𝙞𝙤𝙣 𝘼𝙛𝙩𝙚𝙧 𝙎𝙩𝙧𝙤𝙠𝙚 in Patient with AF and acute IS/TIA European Heart Association Guideline recommends: • 1 days after TIA • 3 days after mild stroke • 6 days after moderate stroke • 12 days after severe stroke Early anticoagulation can decrease a risk of recurrent stroke and embolic events but may increase a risk of secondary hemorrhagic transformation of brain infarcts. The 1-3-6-12-day rule is a known consensus with graded increase in delay of anticoagulation between 1 and 12 days after onset of ischemic stroke or transient ischemic attack(TIA), according to neurological severity based on European expert opinions. However, this rule might be somewhat later than currently used in a real-world practical setting.

Acute Treatment of Hyperkalemia

Acute Treatment of Hyperkalemia – A Practical, Bedside-Oriented Guide Hyperkalemia is a potentially life-threatening electrolyte abnormality that demands prompt recognition and decisive management. The danger lies not only in the absolute potassium value but in its effects on cardiac conduction, which can rapidly progress to fatal arrhythmias. Acute treatment focuses on three parallel goals: stabilizing the cardiac membrane, shifting potassium into cells, and removing excess potassium from the body. Understanding this stepwise approach helps clinicians act quickly and rationally in emergency settings. Why Hyperkalemia Is Dangerous Potassium plays a key role in maintaining the resting membrane potential of cardiac myocytes. Elevated serum potassium reduces the transmembrane gradient, leading to slowed conduction, ECG changes, ventricular arrhythmias, and asystole. Importantly, ECG changes do not always correlate with potassium levels, so treatment decisions should be based on clinical c...

2025 AHA/ACC Hypertension Guidelines Key points

2025 AHA/ACC Hypertension Guidelines Explained: A Clear Summary for Clinicians and Students Hypertension remains one of the most significant contributors to cardiovascular morbidity and mortality worldwide. With continual refinement of evidence and risk-based strategies, the 2025 AHA/ACC Hypertension Guidelines bring an updated, practical approach that clinicians can use in daily practice. To make learning easier, I’ve created a clean and modern infographic summarizing all major recommendations. You can download it below and use it for study, teaching, or clinical reference. Download Infographic (PNG): 2025 Hypertension Guideline Infographic This post breaks down the key points from the guidelines and complements the infographic for a complete understanding. --- BP Categories: Understanding the Updated Thresholds The guidelines maintain the well-established classification of blood pressure: Normal: <120 / <80 Elevated: 120–129 / <80 Stage 1 Hypertension: 130–139 and/or 8...

Dr. Usman's Cardiology Notes

Search This Blog