Pulsus Paradoxus Vs Pulsus Alternans

  • Lenee CastelynBachelor of Dental Surgery. - University of the Western Cape
  • Shazia AsimPhD Scholar (Pharmacology), University of Health Sciences Lahore, Pakistan

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Arterial pulses are essential indicators of cardiovascular health, providing valuable insights into how your heart is functioning. The arterial pulse reflects the rhythmic expulsion of blood from your heart into your arterial system.

Pulsus paradoxus and pulsus alternans both represent unique abnormalities in the arterial pulse, caused by underlying conditions affecting either the heart or lungs. Understanding these arterial pulse abnormalities, the differences between them, and how they can be recognised, is crucial for the accurate diagnosis and treatment of potentially fatal underlying cardiovascular conditions. 

The heart and arterial pulse

The heart is the central organ of the cardiovascular system and plays a pivotal role in generating arterial pulses. Any abnormalities in your arterial pulse might indicate an underlying disturbance or condition affecting your heart.

Structure of the heart

The heart consists of four chambers: two atria and two ventricles. During each cardiac cycle, blood flows from your body into the right atrium, then into the right ventricle, where it is pumped to the lungs to pick up oxygen. Oxygen-rich (oxygenated) blood then returns to the heart through the left atrium, passes into the left ventricle, and is pumped out to supply oxygen and nutrients to the rest of the body (systemic circulation).

Image source: Sutherland C. Biorender

Arterial pulse

Arterial pulses are generated as a result of the cyclic contraction and relaxation of the heart muscle. There are two phases of the heartbeat:

  • Systole is when the heart contracts and pumps blood from the chambers of the heart into the arteries
  • Diastole is when the heart relaxes and allows the chambers to fill with blood

The rhythmic contraction of the ventricles during systole increases blood pressure within the arteries, resulting in a palpable pulse that can be felt at various arterial sites throughout your body (e.g. your wrist, inside the elbow, over the temple, at the side of the neck). This pulse reflects the pressure exerted on the walls of your arteries as blood is pumped out from the heart (systolic blood pressure).

A normal arterial pulse waveform exhibits characteristic features, including:

  • A rapid systolic upstroke
  • A peak systolic pressure
  • A gradual downstroke during diastole

Image source: Sutherland C

These pulses are typically uniform in shape and amplitude under normal physiological conditions. However, alterations in cardiovascular function can lead to abnormalities in your arterial pulse, such as pulsus paradoxus and pulsus alternans. It is important to understand these arterial pulse abnormalities, as they can provide valuable diagnostic insights into underlying cardiovascular conditions.

Pulsus paradoxus

What is pulsus paradoxus?

Pulsus paradoxus (also known as paradoxic pulse or paradoxical pulse) is an abnormally large decrease in systolic blood pressure (>10 mmHg) when you inhale (breathe in).1 Your systolic blood pressure (the top number on a blood pressure reading) is a measure of the pressure your blood is exerting against your artery walls when your heart is beating and pumping blood out (during systole). In contrast, diastolic pressure (the bottom number on a blood pressure reading) is a measure of the pressure in your arteries when your heart is relaxed between heartbeats (during diastole). 

Image source: Sutherland C.

Pulsus paradoxus is a sign that you have an underlying condition that is affecting your heart or lungs. 

How is pulsus paradoxus detected?

Given that pulsus paradoxus is a symptom of some underlying cardiac or respiratory condition, rapid and accurate recognition of this sign is vital to help diagnose these underlying, potentially serious conditions.2 

Pulsus paradoxus can be measured by your healthcare provider using a blood pressure cuff and stethoscope. They will listen to your pulse sounds (Korotkoff sounds) while they inflate and then slowly deflate the cuff to obtain systolic and diastolic blood pressure readings. You will be asked to repeat this reading both when you are breathing in and when you are breathing out to compare the blood pressure during inspiration and expiration.

The two systolic numbers will then be compared from when you breathe in and out. If the difference between these numbers is greater than 10 mmHg it could be an indication that you have pulsus paradoxus.1

It should be noted that automatic blood pressure cuffs cannot accurately measure for pulsus paradoxus.1

What causes pulsus paradoxus?

Pulsus paradoxus is primarily associated with conditions that affect the heart, the pericardium (the sac around the heart), and the lungs. Some potential causes of pulsus paradoxus include:1,3,4

Cardiac causes

  • Cardiac tamponade or pericardial effusion: This condition is caused by a build-up of fluid in the pericardium which puts pressure on the heart. This stops the chambers of the heart from filling properly and hence reduces the ability of the heart to pump blood around your body
  • Constrictive pericarditis: This is a condition where the walls of the pericardium surrounding your heart stiffen and become too thick, preventing your heart from beating properly
  • Restrictive cardiomyopathy: Here, the muscles of your heart ventricles stiffen and cannot fill with blood, reducing blood flow in your heart
  • Acute myocardial infarction (heart attack)
  • Tricuspid atresia: A congenital condition where you are born without a tricuspid valve in your heart - the valve that controls blood flow from the right atrium to the right ventricle

Pulmonary causes 

Other causes

How can pulsus paradoxus be treated or managed?

Pulsus paradoxus itself is not a condition that can be treated - it is a symptom of an underlying condition that might be affecting your heart or lungs. Treatment should therefore address the underlying cause of this pulse abnormality and will vary depending on this underlying condition. For example, treatment might involve:

Pulsus alternans

What is pulsus alternans?

Pulsus alternans (also known as mechanical alternans) is an arterial pulse with alternating strong and weak beats. This is essentially a beat-to-beat change in how strong your heart is contracting while it continues to beat at a constant rate.5

Image source: Sutherland C

Pulsus alternans is almost always indicative of severe ventricular dysfunction and heart failure and typically carries a poor prognosis due to the severity of the heart conditions causing this sign. Therefore, early recognition and appropriate management and intervention are vital to improve patient outcomes. 

How is pulsus alternans detected?

Pulsus alternans can be detected by your healthcare provider by palpating the radial (in the forearm) or femoral (located in the inner thigh) arteries to assess the regularity of the rhythm and strength of the pulse. Pulsus alternans will be indicated by feeling a regular rhythm with alternating strong and weak pulses. This diagnosis is often confirmed using a blood pressure cuff to listen for Korotkoff sounds. Pulsus alternans is indicated by alternating strong and faint Korotkoff sounds.5

To confidently diagnose pulsus alternans, it is important to observe a regular rhythm. Bigeminal pulse is a distinct condition also characterised by alternating strong and weak pulses, but here the rhythm is irregular. 

If pulsus alternans is suspected, a full cardiac workup should then be performed to investigate heart function. This might include:

What causes pulsus alternans?

Pulsus alternas occurs as a result of underlying cardiac distress and dysfunction. It is a symptom of these conditions. 

Pulsus alternans can be grouped into three different types depending on which of the two ventricles are affected: left ventricular alternans, right ventricular alternans, and biventricular alternans (both ventricles). These different variations of pulsus alternans are associated with different conditions.6

Left ventricular alternans

Left ventricular alternans is the most common type of pulsus alternans and occurs when you have severe left ventricular dysfunction (or left-sided heart failure). This could be caused by:5,7,8

Right ventricular alternans

Right ventricular alternans occur when you have right ventricular strain or dysfunction (or right-sided heart failure). This could be caused by:5,7,9

Biventricular alternans

Biventricular alternans is a very rare form of pulsus alternans where both of the ventricles are affected. The cause is not fully understood. It has been reported in cases of:7,9

How can pulsus alternans be treated?

Given that pulsus alternans is a sign of underlying cardiac dysfunction or disease, treatment involves the management of the underlying pathology. For example, this might include:


Pulsus paradoxus and pulsus alternans are both major arterial pulse abnormalities with distinct characteristics, underlying causes, and clinical implications. Pulsus paradoxus is an abnormally large decrease in systolic blood pressure during inspiration, typically associated with cardiac problems like cardiac tamponade or constrictive pericarditis. Pulsus alternans is an arterial pulse with a regular rhythm but alternating strong and weak beats. This pulse abnormality typically indicates severe left ventricular dysfunction, commonly seen in heart failure. 

Treatment of both pulse abnormalities involves addressing the underlying cause, but the prognosis varies depending on the severity of the underlying cardiac pathology and the effectiveness of treatment interventions. It is important to recognise these abnormalities and understanding their underlying causes is essential for the early diagnosis and effective management of primary cardiovascular conditions.


  1. Van Dam MN, Fitzgerald BM. Pulsus paradoxus. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 Mar 14]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK482292/
  2. Hamzaoui O, Monnet X, Teboul JL. Pulsus paradoxus. European Respiratory Journal [Internet]. 2013 Dec 1 [cited 2024 Mar 14];42(6):1696–705. Available from: https://erj.ersjournals.com/content/42/6/1696
  3. Sarkar M, Bhardwaj R, Madabhavi I, Gowda S, Dogra K. Pulsus paradoxus. Clinical Respiratory J [Internet]. 2018 Aug [cited 2024 Mar 14];12(8):2321–31. Available from: https://onlinelibrary.wiley.com/doi/10.1111/crj.12912
  4. Bilchick KC, Wise RA. Paradoxical physical findings described by Kussmaul: pulsus paradoxus and Kussmaul’s sign. The Lancet [Internet]. 2002 Jun [cited 2024 Mar 14];359(9321):1940–2. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0140673602087639
  5. Henery D, Tummala R. Pulsus alternans. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 Mar 14]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK557642/
  6. Nguyen T, Cao LB, Tran M, Movahed A. Biventricular pulsus alternans: An echocardiographic finding in a patient with pulmonary embolism. World J Clin Cases [Internet]. 2013 Aug 16 [cited 2024 Mar 14];1(5):162–5. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3845944/
  7. Vidwan P, Stouffer GA. Biventricular pulsus alternans. Cardiol Res Pract [Internet]. 2009 [cited 2024 Mar 14];2009:703793. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2778180/
  8. Kodama M, Kato K, Hirono S, Okura Y, Hanawa H, Ito M, et al. Mechanical alternans in patients with chronic heart failure. Journal of Cardiac Failure [Internet]. 2001 Jun 1 [cited 2024 Mar 14];7(2):138–45. Available from: https://www.sciencedirect.com/science/article/pii/S1071916401253603
  9. Michaels AD, Browne AE, Varghese P, Chou TM. Intracoronary measurement of pulsus alternans. Catheter Cardiovasc Interv. 2000 Nov;51(3):335–8.

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Charlotte Sutherland

Master of Science – MSc Translational Neuroscience, Imperial College London

Charlotte is a recent MSc Translational Neuroscience graduate from Imperial College London where she undertook research investigating antidepressants and Alzheimer’s disease. She has a strong interest in translational research and is aiming to pursue a PhD in the field of neurodegenerative diseases.

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