Implementing microbubble contrast in the echocardiography laboratory: a sonographer's perspective

Quantitative segmental analysis of myocardial perfusion to differentiate stress cardiomyopathy from acute myocardial infarction: A myocardial contrast echocardiography study

BACKGROUND

Both stress cardiomyopathy (SCMP) and acute myocardial infarction (AMI) present with similar clinical symptoms and signs, and apical akinesis.

HYPOTHESIS

Quantitative segmental analysis of myocardial contrast echocardiography (MCE) helps to differentiate AMI from SCMP.

METHODS

Real-time MCE was performed in 33 consecutive patients who presented with an acute symptom/sign and a new apical akinesis on echocardiography. In 18 left ventricular (LV) myocardial segments, a replenishment curve was obtained in each segment to measure peak plateau myocardial contrast intensity (MCI) (A) and the replenishment curve slope (β). The calibrated MCI was also measured in each segment.

RESULTS

Among 33 patients, 22 were diagnosed with SCMP and 11 were diagnosed with AMI according to comprehensive diagnostic criteria. A, β, Aβ, and the calibrated MCI were lower in akinetic than in normokinetic segments in both the SCMP and AMI groups. In the akinetic segments, A, β, Aβ, and the calibrated MCI in SCMP patients were each higher than those in AMI patients. In patient-based analyses, areas under the ROC curves of A, β, Aβ, and the calibrated MCI for diagnosing AMI were 0.769, 0.607, 0.822, and 0.934, respectively. The optimal cutoff values to diagnose AMI were Aβ < 3.7 dB/sec (sensitivity 82%, specificity 82%) and a calibrated MCI < -23 dB (sensitivity 91%, specificity 95%).

CONCLUSIONS

Although myocardial perfusion is relatively reduced in the akinetic segments of SCMP, a quantitative segmental analysis of myocardial perfusion using MCE helps to discriminate AMI from SCMP.

Clinical application and laboratory protocols for performing contrast echocardiography

Technically difficult echocardiographic studies with suboptimal images remain a significant challenge in clinical practice despite advances in imaging technologies over the past decades. Use of microbubble ultrasound contrast for left ventricular opacification and enhancement of endocardial border detection during rest or stress echocardiography has become an essential component of the operation of the modern echocardiography laboratory. Contrast echocardiography has been demonstrated to improve diagnostic accuracy and confidence across a range of indications including quantitative assessment of left ventricular systolic function, wall motion analysis, and left ventricular structural abnormalities. Enhancement of Doppler signals and myocardial contrast echocardiography for perfusion remain off-label uses. Implementation of a contrast protocol is feasible for most laboratories and both physicians and sonographers will require training in contrast specific imaging techniques for optimal use. Previous concerns regarding the safety of contrast agents have since been addressed by more recent data supporting its excellent safety profile and overall cost-effectiveness.

American Society of Echocardiography Consensus Statement on the Clinical Applications of Ultrasonic Contrast Agents in Echocardiography

ACCREDITATION STATEMENT: The American Society of Echocardiography (ASE) is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The ASE designates this educational activity for a maximum of 1 AMA PRA Category 1 Credit.trade mark Physicians should only claim credit commensurate with the extent of their participation in the activity. The American Registry of Diagnostic Medical Sonographers and Cardiovascular Credentialing International recognize the ASE's certificates and have agreed to honor the credit hours toward their registry requirements for sonographers. The ASE is committed to resolving all conflict-of-interest issues, and its mandate is to retain only those speakers with financial interests that can be reconciled with the goals and educational integrity of the educational program. Disclosure of faculty and commercial support sponsor relationships, if any, have been indicated.

TARGET AUDIENCE

This activity is designed for all cardiovascular physicians, cardiac sonographers, and nurses with a primary interest and knowledge base in the field of echocardiography; in addition, residents, researchers, clinicians, sonographers, and other medical professionals having a specific interest in contrast echocardiography may be included.

OBJECTIVES

Upon completing this activity, participants will be able to: 1. Demonstrate an increased knowledge of the applications for contrast echocardiography and their impact on cardiac diagnosis. 2. Differentiate the available ultrasound contrast agents and ultrasound equipment imaging features to optimize their use. 3. Recognize the indications, benefits, and safety of ultrasound contrast agents, acknowledging the recent labeling changes by the US Food and Drug Administration (FDA) regarding contrast agent use and safety information. 4. Identify specific patient populations that represent potential candidates for the use of contrast agents, to enable cost-effective clinical diagnosis. 5. Incorporate effective teamwork strategies for the implementation of contrast agents in the echocardiography laboratory and establish guidelines for contrast use. 6. Use contrast enhancement for endocardial border delineation and left ventricular opacification in rest and stress echocardiography and unique patient care environments in which echocardiographic image acquisition is frequently challenging, including intensive care units (ICUs) and emergency departments. 7. Effectively use contrast echocardiography for the diagnosis of intracardiac and extracardiac abnormalities, including the identification of complications of acute myocardial infarction. 8. Assess the common pitfalls in contrast imaging and use stepwise, guideline-based contrast equipment setup and contrast agent administration techniques to optimize image acquisition.