Significance of Microbubble Contrast Study in Identification of Right Atrial Masses

   

Alekhya Abburu^1*, Basharat Ahmad², Prabakaran Gopalakrishnan³ and Ataul M. Qureshi⁴

¹AA, MBBS graduate- Clinical Observer, Aultman Deuble Heart and Vascular Center, Canton, Ohio

²BA, MD - Clinical Fellow, Department of Cardiology, Aultman Deuble Heart and Vascular Center, Canton, Ohio 

³PG, MD – Consultant Cardiologist, Department of Cardiology, Aultman Deuble Heart and Vascular Center, Canton, Ohio 

⁴A M.Q, MD – Consultant Cardiologist, Department of Cardiology, Aultman Deuble Heart and Vascular Center, Canton, Ohio

DOI: https://doi.org/10.52793/ACMR.2024.5(4)-91

Abstract

Background: Cardiac masses are exceptionally rare but pose the most dangerous threat to the human body. They may be benign, malignant or tumor-like conditions such as thrombus or extracardiac cysts. The classification of these lesions is an important predictor of mortality. Several factors are considered helpful in establishing a diagnosis and treatment plan such as the location of the mass, age at presentation and imaging characteristics. Left atrium is the most common cardiac mass entity. However, a mass in the right atrium creates unique challenges because of the presence of normal anatomic variants that can mimic a tumor. Right atrial masses are rare and cannot be diagnosed unless a histopathological specimen is obtained. Here we present a case of a female, with two right atrial masses, highlighting the diagnostic challenges in arriving at a definitive diagnosis.

Methods and Result: A 39-year-old healthy female with no medical history presented with acute onset shortness of breath and palpitations. EKG showed new-onset atrial fibrillation with occasional premature ventricular complexes and clinically, she was in acute decompensated heart failure. She was scheduled for a direct current cardioversion and a transesophageal echocardiogram (TEE) was performed which revealed interesting findings of a large 3 cm mobile mass attached to the right atrial wall through a stalk and an underlying small mass of 1.5 x 0.9 cm. Furthermore, microbubble contrast media was utilized to assess the nature of the masses. Contrast-enhanced echocardiographic images presented uptake in the periphery of the large mass but no uptake otherwise. Using this technique, we detected a partially vascularized mass which later turned out to be a vascularized thrombus.

Conclusion: Most of the cardiac tumors are benign and cannot be differentiated from a vascularized thrombus. Echo contrast image enhancement by the ultrasound waves utilizing the echogenic properties of the microbubble contrast agents helps assess various vascularized cardiac structures and tumors, which are difficult to visualize on traditional ultrasound. Using this technique, we detected partially echocardiogenic contrast-enhanced masses that were later detected as an organized thrombus.

Keywords

Right atrial mass; Thrombus; Microbubble contrast study; Transesophageal echocardiogram (TEE).

Introduction

Microbubbles are developed for clinical molecular imaging. They are purely intravascular contrast particles with a diameter of several micrometers. Molecular imaging using microbubble-based ultrasound contrast agents is potentially useful in monitoring the biomarker status of vascular endothelium, enhancing the tumor vasculature and inflammation. It is also useful in detecting ischemia-reperfusion injury zones and thrombi [1]. The bubble surface is coated with suitable ligands that bind to target receptors on vascular endothelium, accumulating at the disease site. Echo from the targeted bubbles helps visualize the biomarker pattern. 90% of masses are either primary, originating from the pericardium or myocardium, or secondary due to malignancy [2]. It is important to differentiate the intracardiac mass as either a thrombus or a tumor. Although very uncommon, right atrial masses possess the same threat as left atrial masses. They may dislodge and cause serious life-threatening cerebral ischemia. A thorough diagnostic approach is required for timely interventions. The gold standard modality for diagnosing cardiac masses is Transesophageal echocardiography by using ultrasound-enhancing agents, which increases the accuracy and reliability of the said, leading to changes in treatment, improving patient outcomes and improving overall healthcare costs [3]. This case is an example of such Contrast-enhanced mass later found to be a thrombus with microbubble contrast study.

Case Presentation

 39-year-old pleasant lady with no significant past medical history presented to the emergency department with complaints of shortness of breath and palpitations. Denies any chest pain, dizziness, PND, or orthopnea. She is not on any medications. She denies the use of tobacco, alcohol or illicit drugs. Family history is positive for atrial fibrillation in the mother. She eventually developed new-onset atrial fibrillation with rapid ventricular response and congestive heart failure. ProBNP was elevated, however cardiac biomarkers were normal. She was given 1 dose of digoxin, 1 dose of Lasix and startezmetoprolol. TEE showed a large right atrial mass measuring 2.6 x 2.9cm attached to the right atrial free wall (Figure 1).

Figure 1: Transesophageal echocardiography showing right atrial masses.

There was also a smaller mass of 1.5 x 0.9cm underneath the larger one. Furthermore, microbubble contrast media was utilized which showed enhanced echocardiogenic images depicting uptake only in the periphery of the larger mass (Figure 2) sparing its central part and no enhancement in the smaller mass. Left Heart catheterization was performed to rule out any underlying coronary diseases, and showed normal RCA & LAD territories (Figure 3). TEE done before cardioversion showed no left atrial thrombus and a 2.6 x 2.9cm mass attached to the right atrium. She was hemodynamically stable with no pertinent findings on the physical exam. The patient was referred to a cardiothoracic surgeon for urgent resection.

Figure 2: 3D echocardiographic findings of right atrial mass showing microbubble contrast uptake in periphery.

Figure 3: Cardiac catheterization done prior to surgery, showing normal RCA and LAD

She was scheduled for an urgent open-heart surgery for resection of the atrial mass with primary closure of the atrial wall, pulmonary vein isolation using AtriCure and Compass radiofrequency system, and left atrial appendage occlusion.