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Related Concept Videos

Aortic Regurgitation I: Introduction01:15

Aortic Regurgitation I: Introduction

IntroductionAortic regurgitation is characterized by the backward flow of blood from the aorta into the left ventricle during diastole and arises from the improper closure of the aortic valve. This condition results in left ventricular volume overload and can stem from both acute and chronic etiologies, each contributing uniquely to the disease's progression and symptomatology.Acute and Chronic CausesAcute aortic regurgitation often results from events that suddenly impair the integrity of the...
Aneurysm III: Interprofessional Care01:26

Aneurysm III: Interprofessional Care

Aneurysm management involves either conservative medical therapy or surgical intervention, depending on the size and symptoms of the aneurysm. Conservative management is generally reserved for smaller, asymptomatic aneurysms, while larger or symptomatic aneurysms often necessitate surgical repair.Conservative Medical TherapyFor small, asymptomatic aneurysms, particularly abdominal aortic aneurysms (AAA) less than 5.5 centimeters in diameter, conservative medical therapy is recommended. This...
Aortic Regurgitation II: Clinical Features and Diagnostic Tests01:22

Aortic Regurgitation II: Clinical Features and Diagnostic Tests

Aortic valve regurgitation (AR) occurs when the aortic valve fails to close properly, allowing blood to flow backward from the aorta into the left ventricle. This backflow can result in two distinct clinical presentations: acute and chronic AR, each characterized by its own set of symptoms and physical findings.Acute Aortic RegurgitationAcute AR presents with a sudden onset of severe symptoms. Patients typically experience profound dyspnea (shortness of breath), chest pain, and signs of left...
Pulmonary Embolism I: Introduction01:29

Pulmonary Embolism I: Introduction

Pulmonary embolism (PE) occurs when a thrombus, fat or air embolus, amniotic fluid, or tumor tissue blocks one or more pulmonary arteries. These blockages originate in the venous system or the right side of the heart.EtiologyPE primarily arises from deep vein thrombosis (DVT) and other hypercoagulable states, such as inherited thrombophilias. Additional etiological factors include venous stasis, commonly seen in obesity, and endothelial injury from surgery and trauma. Less common causes include...
Pulmonary Embolism I: Introduction01:19

Pulmonary Embolism I: Introduction

A blood clot, or thrombus, is a semi-solid mass composed of fibrin, platelets, and red blood cells. When it forms within a vessel, it can obstruct blood flow, known as thrombosis. If part of the clot detaches, it becomes an embolus that can travel and block distant vessels. When this occurs in the pulmonary arteries, it causes a condition known as pulmonary embolism (PE).Origin and ImpactMost often, the embolus originates from a thrombus in the deep veins of the lower limbs, a condition called...
Pulmonary Embolism II: Diagnostic Studies and Interprofessional Care01:29

Pulmonary Embolism II: Diagnostic Studies and Interprofessional Care

Diagnosing Pulmonary EmbolismDiagnosing pulmonary embolism (PE) involves clinical assessment and advanced imaging tests. The preferred diagnostic tool is the spiral (helical) CT scan or CT angiography (CTA), which uses intravenous contrast media to visualize the pulmonary vasculature and identify emboli.A ventilation-perfusion (V/Q) scan is an alternative for patients unable to receive contrast media. This scan includes both perfusion and ventilation scanning. Perfusion scanning involves...

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Related Experiment Video

Updated: Jul 18, 2026

Full-root Aortic Valve Replacement by Stentless Aortic Xenografts in Patients with Small Aortic Roots
12:17

Full-root Aortic Valve Replacement by Stentless Aortic Xenografts in Patients with Small Aortic Roots

Published on: May 21, 2017

Microemboli in aortic valve replacement.

Axel Nötzold1, Ahmed A Khattab, Jürgen Eggers

  • 1Segeberger Kliniken GmbH, Department for Cardiac and Vascular Surgery, Am Kurpark 1, 23795 Bad Segeberg, Germany. axel.noetzold@gmx.de

Expert Review of Cardiovascular Therapy
|December 19, 2006
PubMed
Summary

Microembolic signals (MES) detected after mechanical aortic valve replacement are primarily gaseous microbubbles. Understanding cavitation physics is key to reducing these signals and improving patient outcomes.

Related Experiment Videos

Last Updated: Jul 18, 2026

Full-root Aortic Valve Replacement by Stentless Aortic Xenografts in Patients with Small Aortic Roots
12:17

Full-root Aortic Valve Replacement by Stentless Aortic Xenografts in Patients with Small Aortic Roots

Published on: May 21, 2017

Area of Science:

  • Cardiovascular Ultrasound
  • Biomedical Engineering
  • Fluid Dynamics

Background:

  • Microembolic signals (MES) are frequently detected in patients with mechanical aortic valve prostheses using transcranial Doppler ultrasound.
  • The origin and composition of these signals have been a long-standing enigma.
  • Recent evidence strongly suggests a gaseous nature for these MES.

Purpose of the Study:

  • To elucidate the nature and etiology of microembolic signals (MES) in mechanical aortic valve prosthesis recipients.
  • To discuss the physics of bubble formation, including cavitation, related to mechanical heart valves.
  • To review transcranial Doppler ultrasound techniques for MES detection and discuss clinical implications.

Main Methods:

  • Review of existing literature on MES detection via transcranial Doppler ultrasound.
  • Discussion of cavitation physics (e.g., bubble formation, degassing of blood) relevant to mechanical heart valves.
  • Analysis of historical and current MES measurement techniques.

Main Results:

  • The gaseous nature of MES has been widely established, challenging earlier artifact or solid particle theories.
  • Different types of cavitation occurring at mechanical heart valves are identified as a primary source.
  • Conditions leading to blood degassing and subsequent bubble formation are discussed.

Conclusions:

  • Microembolic signals in mechanical aortic valve recipients are predominantly gaseous microbubbles.
  • Understanding cavitation and blood degassing is crucial for addressing MES.
  • Strategies for designing less thrombogenic prostheses and alternative surgical approaches are needed to minimize MES and their potential clinical impact.