Contrast Echocardiography: Compendium for Clinical Practice

By Harald Becher and Andreas Helfen

This book provides a comprehensive overview of the practical aspects of contrast echocardiography. It also covers all the material in the guidelines published by the American Society of Echocardiography (ASE) in 2018 and the recommendations set out by the European Association of Cardiovascular Imaging (EACVI) in 2017. Contrast echocardiography at present is only used in 5-10% of cases, but this is expected to grow rapidly following the recommendations of the ASE and EACVI. The chapters cover the approved indications and provide practical advice on how to administer the contrast agents and how to optimize the recordings as well as how to deal with the pitfalls. The reader will find all the information on how to use contrast agents for assessment of shunts, LV volumes and function as well as myocardial diseases and masses.  Detailed protocols are included for stress echocardiography and myocardial perfusion imaging. Other topics covered include the use of contrast agents for coronary sonography and transesophageal echocardiography.

Contrast Echocardiography: Compendium for Clinical Practice comprehensively covers all aspects of the clinical use of contrast echocardiography and has been written by two cardiologists who share their experience from their high volume echo laboratories. One of the authors has been a member of both the ASE guidelines and EACVI recommendation writing groups.  It is therefore, a critical text for echocardiographers and sonographers who perform echocardiography.

• Language: English
• Publisher: Springer
• Release date: Jul 3, 2019
• ISBN: 9783030159627

Book preview

© Springer Nature Switzerland AG 2019

Harald Becher and Andreas HelfenContrast Echocardiographyhttps://doi.org/10.1007/978-3-030-15962-7_1

1. Basics of Contrast Enhanced Echocardiography

Harald Becher¹  and Andreas Helfen²

(1)

University of Alberta Hospital, Edmonton, AB, Canada

(2)

St. Marien Hospital, Katholisches Klinikum Lünen GmbH, Lünen, Nordrhein-Westfalen, Germany

1.1 Ultrasound Contrast Agents

1.2 Right Heart Contrast Agent

1.2.1 Indications

1.2.2 Preparation of the Agitated Saline

1.2.3 Adverse Effects of Agitated Saline

1.3 Left Heart Contrast Agents

1.3.1 Indications

1.3.2 Contraindications

1.3.3 Characteristics of Left Heart Contrast Media

1.3.4 Adverse Effects of Left Heart Contrast Agents

1.3.5 Degradation of the Contrast Agents

1.3.6 Preparation of the Contrast Agent

1.3.7 Preparation of the Patient

1.4 Machine Settings for Contrast Echocardiography

1.4.1 Right-Heart Contrast Media

1.4.2 Left Heart Contrast Agents

1.5 Application of Contrast Agents : IV Bolus and Infusion Pump

1.5.1 Indications

1.5.2 How to Use the Contrast Pump

References

Electronic supplementary material

The online version of this chapter (https://​doi.​org/​10.​1007/​978-3-030-15962-7_​1) contains supplementary material, which is available to authorized users.

1.1 Ultrasound Contrast Agents

Ultrasound contrast agents are used to enhance the echogenicity of the blood. The echogenicity is determined by the acoustic impedance, which depends on the difference between the density of blood components and the densities of the components of the contrast agent. The density of air, sulphur hexafluoride or perflutren gases, is about 100,000 times lower than the density of the serum. Therefore, bubbles containing these gases make excellent contrast agents.

Unlike red blood cells, having a medium diameter of 2–7.5 μm, gas bubbles with a diameter of more than 9 μm diameter are unable to pass through pulmonary capillaries. Agitated saline contains air bubbles with a diameter of 32 ± 8 μm. When agitated saline is injected intravenously, only the right atrium and the right ventricle are opacified (Jeon et al. 2002). In contrast, the microbubbles in commercially available ultrasound contrast agents are so small (2–4.5 μm), that up to 98% of the bubbles can pass the lung capillaries allowing the left atrium, left ventricle and arteries to be opacified.

Therefore, these agents are called left heart contrast agents, whereas agitated saline is a right-heart contrast agent.

There have been several recommendations and guidelines for the practice of contrast echocardiography. In 2009, the European Association of Echocardiography (EAE) published recommendations for the first-time about the indications and how to use contrast agents in echocardiography (Senior et al. 2009). In 2017 updated recommendations were published by the European Association of Cardiovascular Imaging, and in 2018 the American Society of Echocardiography (ASE) published similar recommendations (Senior et al. 2017; Porter et al. 2018). The recent guidelines of the ASE and EACVI extend the indications of contrast echocardiography and provide advice for clinical practice based on the large amount of evidence, which became available during the last 10 years.

In order to implement the recommendations and guidelines, training programs have been recommended for contrast echocardiography by the ASE and EACVI. The Core Syllabus of the European Association for Cardiovascular Imaging (Cosyns et al. 2013) recommends training in contrast echocardiography as part of the training in general echocardiography. Chapter 8 refers to the Core Syllabus.

1.2 Right Heart Contrast Agent

1.2.1 Indications

Right-heart contrast agents can be used to rule in or out intracardiac and intrapulmonary shunts, as well as for enhancement of colour- and CW-Doppler signals. The most frequent indication is the assessment of a patent foramen ovale (PFO).

1.2.1.1 Patent Foramen Ovale (PFO)

A PFO is not a fixed defect of the interatrial septum like an ASD, but an incomplete fusion of the septum secundum and the septum primum (Silvestry et al. 2015). A PFO can be found in around 35% of people younger than 30 years of age and about 20% of the people aged over 80 years. In the case of a PFO, the septum primum and secundum behave like a valve which is closed as long as the left atrial pressure exceeds the right atrial pressure. However, when the RA pressure exceeds the LA pressure the septum secundum is pushed away from the septum primum and blood flows from the RA into the LA. Sometimes a continuous tunnel like gap without valve mechanism can be detected (Saric et al. 2016).

In patients with dilated left atrium and stretched interatrial septum (secundum) a continuous left-to-right shunt is possible, and the PFO is referred to as stretched PFO (Fig. 1.1, Video 1.1).

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Fig. 1.1

Stretched PFO. Dilatation of the left atrium results in an expansion of the superior edge of the septum secundum with left-to-right shunt due the increased left-atrial pressure (Video 1.1)

In 40% of subjects without PFO, the fusion of the septum primum and the septum secundum involves the entire overlap area. Figures 1.2 and 1.3 show the normal anatomy of the septum primum and septum secundum on TEE recordings.

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Fig. 1.2

Normal anatomy of the atrial septum , displayed in TEE (mid oesophageal probe position, angle of 100°)

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Fig. 1.3

Top: Biplane transoesophageal imaging of the atrial septum at 5° and 95°. There is complete fusion of the overlap zone between septum primum and septum secundum. After injection of agitated saline there is no evidence of a PFO or a pouch (bottom)

In cases of incomplete fusion, left atrial or right atrial pouches can be found. When the attachment of the septa is limited to the caudal part of the overlap zone, a LA septal pouch is present. Only in about 10% of cases will the attachment involve the cranial part of the overlap zone, which creates a RA septal pouch (Krishnan et al. 2010). Figure 1.4 shows the different septal pouch forms and in Fig. 1.5 a LA septal pouch is displayed by