Spontaneous Echocardiographic Contrast Associated with Portosystemic Shunt Due to Persistent Patent Ductus Venosus

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Spontaneous Echocardiographic Contrast Associated with Portosystemic Shunt Due to Persistent Patent Ductus Venosus

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Amir Toib, MD, MSc, Seth B. Goldstein, MD, Geetika Khanna, MBBS, MS, Charles E. Canter, MD, Caroline K. Lee, MD, David T. Balzer, MD, and Gautam K. Singh, MD Divisions of Pediatric Cardiology and Diagnostic Radiology, Departments of Pediatrics and Radiology, Washington University School of Medicine, St. Louis, Mo, USA ABSTRACT

We describe a case of an infant with a single ventricle physiology, who presented with spontaneous microbubbles originating from her inferior vena cava. Imaging revealed a persistent patent ductus venosus, leading to a portosystemic shunt, streaming the microbubbles into the heart. We discuss the possible mechanisms for this rare phenomenon in a child. Key Words. Spontaneous Echo Contrast; Patent Ductus Venosus; Portosystemic Shunt

Introduction

Case Report

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A 6-month-old female infant with tricuspid atresia, normally related great arteries and pulmonary stenosis, who was previously palliated with placement of a right modified Blalock–Taussig (BT) shunt, presented with a 1-day history of tachypnea and desaturation to 70% (from her baseline saturations of 80%) and was admitted to our cardiology service. In the months prior to the admission she had difficulty gaining weight, despite optimal caloric intake. She also had intermittent bloody stools. Workup on admission included an echocardiogram, which demonstrated tricuspid atresia, a right–to-left atrial level shunt, hypoplastic right ventricle, LV with normal systolic function and a patent BT shunt. Spontaneous echocardiographic contrast was noted throughout the heart entering the right atrium (RA) from her dilated hepatic veins (in the absence of IV access) (Figure 1, Movies S1 and S2). Relevant blood work revealed albumin of 3.6 g/ dL, ammonia level of 66 mmol/L (normal 10–50), B-type natriuretic peptide level of 525 pg/mL (normal 0–100), D dimer > 20 mg/mL (normal 0.2–0.5), antithrombin III level of 55% (normal 80–140%), protein C level of 39% (normal 80–160%), and a fibrinogen level of 151 mg/dL (normal 177–401). Abdominal x-ray revealed no evidence of pneumatosis or portal vein gas. The GI evaluation

pontaneous contrast is defined as the appearance of sonographic contrast in the heart without antecedent intravenous (IV) injection or events known to cause intravascular gas, such as trauma, obstetric accidents, or decompression.1 Spontaneous echocardiographic contrast can originate in the left heart as a result of respiratory maneuvers, such as coughing or Valsalva,2 prosthetic mitral valve, atrial arrhythmia, or dilated left ventricle (LV) with reduced contractility.3,4 The differential diagnosis of spontaneous contrast originating from the right side of the circulation includes constrictive pericarditis,5 gas originating from the gastrointestinal (GI) tract,5 microthrombi,5,6 low cardiac output states5,7,8 hypoalbuminemia,8 accidental IV bubbles,1,5,7 and microcavitations as a result of tricuspid valve abnormalities and right heart failure.1,7 It is important to categorize spontaneous contrast according to its mechanism of generation, which will influence the echocardiographic appearance of this phenomenon. Microthrombi and low cardiac output usually generate a hazy “smoke-like” appearance.3,5 The other etiologies will manifest as discrete microbubbles. The unique case presented here combines an unusual anatomical variant with a rare echocardiographic phenomenon that is hardly described in the pediatric literature. Congenit Heart Dis. 2012;7:E18–E21

© 2011 Wiley Periodicals, Inc.

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Spontaneous Echo Contrast A

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Figure 1. (A) Apical four-chamber view demonstrating tricuspid atresia, atrial level shunt with a right-to-left flow of spontaneous echo contrast that is seen throughout the heart. (B) Subcostal coronal view demonstrating an atrial septum that bows right to left. Spontaneous echo contrast is seen in dilated hepatic veins flowing through the atrial septum from right atrium (RA) to left atrium. (C) M mode echo through the left ventricle (LV) demonstrating a “fire works” appearance of the microbubbles scattering.

concluded that the bloody stool was a result of benign rectal bleeding of infancy. Chest and abdominal computerized tomography (CT) angiography demonstrated congestive hepatopathy and a patent ductus venosus (Figure 2).

Figure 2. Coronal (A) and sagittal (B) 10-mm maximum intensity projection CT images show the patent ductus venosus (arrow) between the left portal vein (LPV) and confluence of the hepatic veins/inferior vena cava (IVC). Dilation of the inferior vena cava, hepatic veins, and right atrium is present secondary to tricuspid atresia.

Cardiac catheterization confirmed the diagnosis of persistent patent ductus venosus (Figure 3A) leading to a large portosystemic shunt. Baseline hemodynamics demonstrated a mean SVC pressure of 10 mm Hg, mean RA pressure of 9 mm Hg and a mean pressure of 11 mm Hg in the portal vein. The portal vein was subsequently balloon occluded. After approximately 15 minutes’ time, the portal venous mean pressure was remeasured Congenit Heart Dis. 2012;7:E18–E21

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Toib et al. priately). Her ammonia normalized (33 mmol/L) and follow up echocardiogram demonstrated resolution of her spontaneous contrast (Figure 4). Discussion

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Figure 3. (A) Anteroposterior (AP) view with contrast injection demonstrating the patent ductus venosus. Access obtained through the right internal jugular vein. Catheter course is through the right atrium (RA), inferior vena cava (IVC) into the patent ductus venosus (arrow). Also visible are the left portal vein (LPV) and dilated hepatic veins. (B) AP view with contrast injection after placement of a vascular plug (arrow) demonstrates complete occlusion of the ductus venosus with no residual shunt.

at 8 mm Hg. Because there was no increased portal vein pressure with test occlusion of the shunt, it was occluded with a vascular plug (Figure 3B). Following the ductus venosus occlusion, the child improved clinically (oxygen saturation stabilized around 80% and she gained weight approCongenit Heart Dis. 2012;7:E18–E21

The patient presented here had spontaneous contrast originating from her right side of the circulation. This rare presentation in a child may be the manifestation of several ominous clinical conditions that were ruled out. She did not have pericarditis or hypoalbuminemia. Necrotizing enterocolitis or other obvious GI source of air was ruled out. She did have some hematologic abnormalities, but these will give a “smoke-like” appearance and not discrete microbubbles.3,5 She did not have an IV line as a source of air bubbles. Microcavitation generation as a result of her tricuspid atresia and right heart failure is a possible mechanism. The local pressure in a regurgitant jet of blood might be lowered as a result of the Bernoulli Effect, enough to result in spontaneous cavitations.1 However, it would not explain the appearance of microbubbles in the hepatic veins and inferior vena cava. The most likely cause of the microbubbles in this case is gas originating from the GI tract. Although none identified, intramural abnormalities could be easily missed on a CT angiogram or abdominal x-ray of a small child. A hypothesis postulated in a case report suggested that gas absorbed from the intestines into the circulation, in the presence of a portosystemic shunt, may cause spontaneous echocardiographic contrast.1 The intermittent presence of spontaneous contrast in the right heart suggests that it may be related in time to meals when carbon dioxide production in the duodenum increases. The fact that echocardiographic contrast was no longer seen in the heart after the occlusion of the ductus venosus is consistent with a portal origin of the microbubbles. We speculate that another possible mechanism could be that the microbubbles in the present case may have been the result of intestinal lipid particles bypassing the liver through her portosystemic shunt. Such hypothesis for this phenomenon, which has not been previously described, is consistent with the fact that lipid particles are reported as diagnostic echocardiographic contrast agents.9 Disclosures

Dr Balzer is a proctor for AGA Medical Corporation.

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Spontaneous Echo Contrast

Figure 4. Apical four-chamber view demonstrating the same anatomy as in Figure 1A without evidence of spontaneous echo contrast.

Corresponding Author: Amir Toib, MD, Division of Pediatric Cardiology, Campus Box 8116, One Children’s Place, St. Louis, MO 63110, USA. Tel: (+314) 454-6095; Fax: (+314) 454-2561; E-mail: toiba@ kids.wustl.edu Conflict of interest: None.

Accepted in final form: June 11, 2011. References

1 Meltzer RS, Lancee CT, Swart GR, Roelandt J. Spontaneous echocardiographic contrast on the right side of the heart. J Clin Ultrasound. 1982;10:240–242. 2 Lopez-Haldon J, Lopez-Pardo F, Rodriguez-Puras MJ, Martinez-Martinez A. Patent foramen ovale not so patent. Echocardiography. 2009;26:465–468. 3 Black IW. Spontaneous echo contrast: where there’s smoke there’s fire. Echocardiography. 2000;17:373– 382. 4 Kozdag G, Ertas G, Sahin T, et al. Dilated cardiomyopathy, spontaneous echo contrast in the aorta and embolic events. Acta Cardiol. 2010;65:9–14. 5 Segal R, Baltazar RF, Mower MM, Stewart C. Spontaneous contrast visualization on the right side of the heart during echocardiography. Am J Med Sci. 1986;292:363–366. 6 Kozelj M, Ramovsbreve A. Spontaneous microbubbles in transit in the right cardiac chambers. Echocardiography. 1996;13:401–404.

7 Meltzer RS, Klig V, Visser CA, Teichholz LE. Spontaneous echographic contrast in the inferior vena cava. Am Heart J. 1985;110:826–830. 8 Hadash A, Braver Y, Lorber A. Spontaneous echoes due to hypoalbuminemia. Cardiol Young. 2004;14: 560–561. 9 Sijl J, Gaud E, Frinking PJ, et al. Acoustic characterization of single ultrasound contrast agent microbubbles. J Acoust Soc Am. 2008;124:4091–4097. Supporting Information Additional Supporting Information may be found in the online version of this article: Movie S1. 2D echocardiography in the apical fourchamber view, demonstrating spontaneous echo contrast throughout the heart. Best viewed with Windows Media Player. Movie S2. 2D echocardiography in the subcostal view, demonstrating spontaneous echo contrast originating from the dilated hepatic veins. Best viewed with Windows Media Player. Please note: Wiley–Blackwell are not responsible for the content or functionality of any supporting materials supplied by the authors. Any queries (other than missing material) should be directed to the corresponding author for the article.

Congenit Heart Dis. 2012;7:E18–E21