Identification of cardiac masses and abnormal blood flow patterns with harmonic power Doppler contrast echocardiography

Clinical practice of contrast echocardiography: recommendation by the European Association of Cardiovascular Imaging (EACVI) 2017

Contrast echocardiography is widely used in cardiology. It is applied to improve image quality, reader confidence and reproducibility both for assessing left ventricular (LV) structure and function at rest and for assessing global and regional function in stress echocardiography. The use of contrast in echocardiography has now extended beyond cardiac structure and function assessment to evaluation of perfusion both of the myocardium and of the intracardiac structures. Safety of contrast agents have now been addressed in large patient population and these studies clearly established its excellent safety profile. This document, based on clinical trials, randomized and multicentre studies and published clinical experience, has established clear recommendations for the use of contrast in various clinical conditions with evidence-based protocols.

Contrast enhanced transesophageal echocardiography in patients with atrial fibrillation referred to electrical cardioversion improves atrial thrombus detection and may reduce associated thromboembolic events

Aims

Transesophageal echocardiography (TEE) is the gold standard for the detection of thrombi in patients with atrial fibrillation (AF) before undergoing early electrical cardioversion (CV). However, TEE generates inconclusive results in a considerable number of patients. This study investigated the influence of contrast enhancement on interpretability of TEE for the detection of left atrial (LA) thrombi compared to conventional TEE and assessed, whether there are differences in the rate of thromboembolic events after electrical cardioversion.

Methods

Of 180 patients with AF (51 females, 65.2±13 years) who were referred to CV, 90 were examined with native imaging and contrast enhancement within the same examination (group 1), and 90 were examined with native TEE alone and served as control (group 2). Cineloops of the multiplane examination of the LA and LA appendage (LAA) were stored digitally before and, in group 1, after intravenous bolus application of a transpulmonary contrast agent. Images of group 1 were assessed offline and the diagnosis of LA thrombi was made semi-quantitatively: 1= thrombus present; 2=inconclusive result; 3=no thrombus. The presence of spontaneous echocontrast (SEC) was registered and flow velocity in the LA appendage (LAA-flow) was measured. All patients in whom CV was performed were followed up for 1 year or until relapse of AF. CV related adverse events were defined as any thromboembolic event within 1 week after CV.

Results

No serious adverse events occurred during TEE and contrast enhanced imaging. In group 1 atrial thrombi were diagnosed in 14 (15.6%) during native and in 10 (11.1%) patients during contrast enhanced imaging (p<0.001). Of the 10 patients with thrombi in the contrast TEE group, 7 revealed a decreased LAA-flow (≤0,3m/s) and 8 showed moderate or marked SEC. Uncertain results were significantly more common during native imaging than with contrast enhanced TEE (16 vs. 5 patients, p<0.01). Thrombi could definitely be excluded in 60 (66.7%) during conventional and in 75 patients (83.3%) during contrast enhanced TEE (p<0.01). CV was performed subsequently after exclusion of thrombi and at the discretion of the investigator. In group 1, 74 patients (82.2%) were cardioverted and no patient suffered a CV related complication (p=0.084). In group 2, 76 patients (84.4%) underwent CV, of whom 3 suffered a thromboembolic complication after CV (2 strokes, 1 peripheral embolism).

Conclusion

In patients with AF planned for CV contrast enhancement renders TEE images more interpretable, facilitates the exclusion of atrial thrombi and may reduce the rate of embolic adverse events.

Echocardiography in the diagnosis left ventricular noncompaction

Echocardiography is the method of choice to establish a diagnosis and determine a treatment plan for patients with noncompaction of ventricular myocardium (NVM). The 2-dimentional echocardiography, 3-dimentional echocardiography, color Doppler echocardiography and contrast-enhanced echocardiography are of critical importance for diagnosis and family screening of NVM.

Clinical utility of contrast-enhanced echocardiography

Over the past three decades, echocardiography has become a major diagnostic tool in the arsenal of clinical cardiology for real-time imaging of cardiac dynamics. More and more, cardiologists' decisions are based on images created from ultrasound wave reflections. From the time ultrasound imaging technology provided the first insight into a human heart, our diagnostic capabilities have increased exponentially as a result of our growing knowledge and developing technologies. One of the most intriguing developments that brought about a decade-long combination of expectations and disappointments was the introduction of echocardiographic contrast agents. Despite repeated waves of controversy regarding the readiness of this technology for clinical use, it has overcome multiple hurdles and currently provides useful clinical information that helps cardiologists to diagnose heart disease accurately. Since the initial reports on the use of ultrasound contrast media such as agitated saline or renografin, the major advances in the field of contrast echocardiography have included (1) the development of stable perfluorocarbon-filled microbubbles, frequently referred to as second-generation contrast agents; and (2) the development of contrast-targeted nonlinear imaging modes, such as harmonic imaging, pulse inversion, and power modulation, which allow consistent real-time visualization of these agents. These contrast agents in conjunction with the new imaging technology constitute powerful tools that improve our ability to evaluate left ventricular function and myocardial perfusion, and allow differential diagnosis of thrombi and intravascular masses. In this manuscript, we briefly review some of the literature that has provided the scientific basis for the use of echocardiographic contrast agents in the context of these important variables.

The value of non-contrast harmonic transthoracic echocardiography for the detection of left ventricular thrombi in patients with cardiomyopathy: comparison with contrast-enhanced magnetic resonance imaging

We sought to assess the value of non-contrast enhanced transthoracic harmonic echocardiography (TEE) for the visualization of left ventricular thrombi in 34 patients with cardiomyopathy. Results were compared to contrast-enhanced magnetic resonance imaging as reference standard. Maximal thrombus size was quantified with both modalities. Magnetic resonance imaging demonstrated thrombi in 15 patients. In these subjects echocardiography was negative in seven patients. Thrombi were excluded in 19 patients with magnetic resonance while echocardiography was deemed positive in 5 subjects. Thrombus size by ce-CMR was not different for clots visualized or not visualized by echocardiography (P = 0.71). Moreover, observer agreement was superior for ce-CMR (kappa = 0.94) as compared to TTE (kappa= 0.71). Non-contrast-enhanced harmonic TTE has limited value for the visualization of thrombi in patients with cardiomyopathy.

The Echocardiographic Evaluation of Intracardiac Masses: A Review

Echocardiography is an invaluable procedure for the evaluation of intracardiac masses, and can reliably identify mass location, attachment, shape, size, and mobility, while defining the presence and extent of any consequent hemodynamic derangement. With careful attention to mass location and morphology, and appropriate application of clinical information, echocardiography can usually distinguish between the 3 principal intracardiac masses: tumor, thrombus, and vegetation. Transesophageal imaging frequently adds additional important information to the assessment of mass lesions and should always be considered when image quality is inadequate or pertinent clinical questions remain unanswered with surface imaging. This review will focus on primary and metastatic tumors of the heart.

Delineation of intracardiac shunts using contrast echocardiography

Contrast echocardiography is useful to visualize the endocardial borders of the left ventricle and improve the signal intensity of spectral Doppler signals. It can also help to define intracardiac flow dynamics in complex situations. We report 2 cases where contrast echocardiography improved the delineation of complex shunts and also provided new information not available by conventional echocardiography.

Diagnosis of coronary pseudoaneurysm by Optison

Intravenous contrast agents that traverse the pulmonary circulation have been used for endocardial border definition, myocardial perfusion, diagnosis of intracardiac thrombi, and in cardiovascular emergencies such as myocardial rupture. We report a patient who presented with a new inferior myocardial infarction and an extracardiac mass compressing the right atrium, in whom diagnosis of right coronary pseudoaneurysm was made on the basis of delayed appearance of Optison contrast into the pseudoaneurysm and was subsequently confirmed by angiography and surgery. Thus, we extend the diagnostic indication of myocardial contrast agents to patients with extracardiac masses.

Assessment of the vascularity of a left ventricular mass using myocardial contrast echocardiography

In addition to a thrombus, an intracardiac mass lesion can represent a primary cardiac tumor, or a metastatic lesion to the heart. The echocardiographic appearance and location of the mass, as well as the associated clinical scenario provide useful clues regarding cause, but these echocardiographic features alone may not always be diagnostic. Because most benign cardiac tumors are relatively avascular, the vascularity of a mass may be a feature that can help differentiate benign from malignant tumors. We present a case of a patient with a history of malignant melanoma who was found incidentally to have a cardiac mass on echocardiography. Contrast echocardiography (CE) was used to evaluate the vascularity of the mass. This case is compared with another patient with an apical thrombus, which represents an "avascular" intracardiac structure.

Use of transesophageal contrast echocardiography for excluding left atrial appendage thrombi in patients with atrial fibrillation before cardioversion

Transesophageal echocardiographic (TEE) guidance of cardioversion in patients with atrial fibrillation is an alternative method to conventional anticoagulation. Although TEE is considered the gold standard for excluding left atrial (LA) thrombi, in some patients dense spontaneous echo contrast (SEC) and artifacts may hamper the identification or exclusion of LA thrombi. Often those patients are refused cardioversion. The purpose of this study was to determine whether the application of echo contrast (Optison, Mallinckrodt, San Diego, Calif) facilitates the exclusion of LA appendage thrombi in this patient group and allows for safer cardioversion. Forty-one patients with atrial fibrillation and dense SEC or inconclusive TEE findings were given echo contrast. Fourteen patients with sinus rhythm served as control participants. Echo contrast completely reduced artifacts in 13 of 22 patients. In 12 of 19 patients with SEC, the LA appendage was completely filled after the application of echo contrast and, thus, SEC was completely suppressed. In 13 of 41 patients, it was filled incompletely and in 9 of 41 patients, a new mass resembling a thrombus was detected. In total, of 25 of 41 patients with inconclusive TEE findings an atrial thrombus was definitively excluded. Those patients underwent cardioversion. None of those patients had a cerebral embolic complication as assessed by cranial magnetic resonance imaging. Thus, the application of echo contrast may facilitate the TEE exclusion of LA appendage thrombi and, hence, improve the safety of TEE-guided cardioversion.

Recent advances in echocardiographic evaluation of left ventricular anatomy, perfusion, and function

This article provides a brief overview of several recently developed, emerging technologies and discusses their potential uses on clinical grounds. These new technologies include three-dimensional imaging, objective automated evaluation of ventricular function with acoustic quantification, assessment of regional ventricular performance using color kinesis and tissue Doppler imaging, harmonic imaging, and power Doppler imaging. Our hope is that readers will gain a better understanding of the principles underlying these technological advances, which will help them to integrate these new techniques efficiently into their clinical practices.