What is Pulsus Paradoxus?

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Definition of Pulsus Paradoxus:

Pulsus paradoxus is defined as a decrease in systolic blood pressure of greater than 10 mm Hg with inspiration. It is detected by inflating a blood pressure cuff above systolic pressure and then slowly deflating it. Pulsus paradoxus is caused by conditions which tighten the space around the beating heart, e.g., constrictive pericarditis, acute cardiac tamponade, obstructive lung disease, tension pneumothorax, severe asthma, or restrictive cardiomyopathy.

What happens when a normal person inspires?

Now, in a normal person, the heart is surrounded by plenty of free space around it. So when a healthy person inhales, the right ventricle expands due to increased venous return, and this right-ventricular expansion has no effect on the functionality of the left side of the heart.

What happens when a person with a constrictive cardiac disease inspires?

However, in any pathologic condition like constrictive pericarditis, this free space surrounding the heart is reduced. So when a person with constrictive pericarditis inhales, the right ventricle pushes into the left ventricle compressing it and decreasing the ejection fraction causing transient hypotension. This means that if you're measuring the blood pressure in a patient with pulsus paradoxus, the Korotkoff sounds will be heard only when the patient is expiring and not while inspiring because the blood pressure drops while inspiring.


So whenever there is transient hypotension with inhalation, the person is suffering from a constrictive cardiac pathology.

Additional Reading:

Basic Cardiology

1. Electrical Activity of the Heart
2. Heart Muscle Mechanics
3. Heart Sounds and Murmurs
4. Additional FAQ on Heart Sounds and Murmurs
5. Cardiac Conduction Diagram
6. Blood Pressures in Cardiac Chambers
7. What is Pulsus Paradoxus?
8. FAQ on Heart Murmurs and Mechanisms of Turbulent Flow
9. Notes on Fetal Circulation
10. FAQ on Ischemic Myocardial Infarction
11. FAQ on Electrocardiograms / ECG / EKG
12. FAQ on Cardiac Conduction
13. The Heart as a Pump, the Cardiac cycle and Cardiac Output
14. What are the most common causes of aortic stenosis?
15. What is Pulseless Electrical Activity?
16. Causes and Complications of Arteriovenous Fistulas
17. CHADS2 Score for Atrial Fibrillation Stroke Risk
18. How to Reduce Blood Pressure without Medications?
19. Types of Shock
20. Locations of Heart Murmurs on Chest Wall
21. Types of Heart Blocks

Electrocardiogram (EKG/ECG) Topics

1. EKG Chest Leads
2. EKG Limb Leads
3. Quick 12-Lead ECG/EKG Format

Cardiology Videos

1. Video of Cardiology Examination in a Clinical Setting

Medical Images

Useful Medical Images & Diagrams (link opens in a new window)

Related Topics

1. Thorax Anatomy
2. Vascular Disorders
3. Heart Disorders
4. Histology of the Cardiovascular System
5. Jugular Venous Distention Workup
6. ER Chest Pain Workup
7. Cardiac Examination for Internal Medicine
8. FAQ on Blood Pressure
9. FAQ on principles of fluid and flow dynamics of Blood

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