Ann Thorac Surg 1997;63:1475-1477
© 1997 The Society of Thoracic Surgeons
Case Report
MRI in the Evaluation and Management of a Newborn Infant With Cardiac Rhabdomyoma
Robert Berkenblit, MD,
Hugo Spindola-Franco, MD,
Robert W. M. Frater, MD,
Bernard B. Fish, MD,
Julie S. Glickstein, MD
Departments of Radiology, Cardiothoracic Surgery, and Pediatrics (Cardiology), Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, and Section of Pediatric Cardiology, New York Medical College, Valhalla, New York
Accepted for publication December 18, 1996.
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Abstract
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A newborn infant presented with a life-threatening cardiac arrhythmia. Echocardiography showed a large cardiac mass growing exophytically in the region of the left atrial appendage extending along the left ventricular wall but showedno clear tissue plane between the mass and the left ventricular wall. Based on the echocardiogram, surgical resection might damage the left ventricular wall. Magnetic resonance imaging demonstrated a clear plane of demarcation, making surgical resection a viable life-saving option.
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Introduction
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A 2-day-old, 4.5-kg full-term infant was transferred to the neonatal intensive care unit at Montefiore Medical Center with a heart rate of 300 beats/min. An initial evaluation revealed the following vital signs: blood pressure, 50/30 mm Hg; respiration rate, 70/min; and heart rate, 300 beats/min. A grade 2/6 soft systolic murmur was heard at the left sternal border, radiating to the apex. The lungs were clear. The liver edge was 5 cm below the right costal margin. All pulses were weak, and the capillary refill was greater than 3 seconds. No hypopigmented areas (ash leaf spots) were noted on the skin. The electrocardiogram revealed a wide complex tachycardia, which, when transiently converted, revealed a normal sinus rhythm with a left bundle-branch block pattern.
The echocardiogram demonstrated a large mass on the posterolateral aspect of the left ventricular wall (Fig 1
), extending onto the surface of the left atrium and the pulmonary artery. No intracardiac masses were found. The right and left ventricular outflow tracts were unobstructed. Moderate mitral regurgitation, mild tricuspid regurgitation, and marked hypokinesis of both ventricles were noted.
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Fig 1. . Two-dimensional echocardiogram of the heart in the four-chamber view demonstrates a large echogenic mass (M) abutting the left ventricle (LV) and the left atrium (LA). The possibility of invasion of the mitral valve (arrow) could not be excluded. The left ventricular wall could not be demonstrated to be free of the lesion. (RA = right atrium; RV = right ventricle.)
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The tachyarrhythmia persisted despite aggressive medical therapy and direct-current cardioversion was only transiently successful; thus, surgical resection was considered the only option to control the tachyarrhythmia. In the absence of a plane of dissection on the echocardiogram, operation did not seem feasible. Emergency magnetic resonance imaging (MRI) was therefore performed.
The infant was clinically unstable; thus, only T1-weighted spin echo images were obtained. These images revealed a mass measuring approximately 4.5 x 4.5 x 4 cm located in the region of the left atrial appendage behind the superior segment of the left ventricle and the left atrium (Fig 2). The mass arose from the superior aspect of the interventricular septum and displaced the main pulmonary artery superiorly and the ascending aorta medially. Most importantly, a clear plane was present between the mass and the left ventricular wall, demonstrating that the tumor could be resected without significant damage to the heart.
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Fig 2. . (A) Spin echo T1-weighted magnetic resonance image (TR-625 ms, TE-30 ms) in the sagittal plane demonstrates a large mass (M) of intermediate signal intensity superior and posterior to the left ventricle (LV). The distinction between the mass and the myocardium is clearly identified (arrows). (B) Spin echo T1-weighted magnetic resonance image (TR-600 ms, TE-30 ms) in the axial plane demonstrates the mass (M) posterior to the left ventricle (LV). The arrow indicates the tissue plane separating the mass from the LV wall. Incidentally noted is consolidation in the left lower lobe, just posterior to the mass.
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At operation the MRI findings were confirmed. The mass arose from within the interventricular septum. A plane of dissection was found between the tumor and two fascicles of the myocardium, one a part of the septum and one a part of the left ventricular free wall. This plane allowed surgical resection without compromising vital cardiac structures. Planes were also found between the tumor and the aorta, pulmonary artery, and left atrial appendage. The mass was supplied by small branches of the left circumflex coronary artery. Histologic sections demonstrated the mass to be a rhabdomyoma. A portion of the histologic specimen resembled conduction tissue, raising the possibility that a reentry mechanism caused the tachycardia.
Two years following the operation the infant has no recurrent tumor on echocardiography, no arrhythmia, and no clinical or laboratory evidence of tuberous sclerosis.
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Comment
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An unusual feature of the tumor was its exophytic growth. No intracavitary mass was demonstrated, and only minor intramural extension was present. In contrast, rhabdomyomas, the most common cardiac tumor in infancy [1], almost invariably arise within the ventricles, originating from the interventricular septum near the crista supraventricularis [2] and adjacent ventricular wall. Other locations include the atria and papillary muscles. Rhabdomyomas are often multiple, and extensive diffuse nodularity may also occur [3]. Clinical manifestations include arrhythmias, obstruction to blood flow, and ischemia due to coronary artery compression [4]. Spontaneous regression has been observed with apoptosis proposed as the mechanism [5]. Rhabdomyomas can be associated with tuberous sclerosis in 51% to 86% of cases [6].
Chest roentgenograms may be normal or may reveal an enlarged heart. Angiocardiography, once considered the definitive diagnostic procedure, is now often not necessary. Instead, echocardiography is the primary method to delineate the location of rhabdomyomas, and to quantify obstruction to blood flow in fetuses, infants, and children [4]. Magnetic resonance imaging may demonstrate a mass with moderately increased signal intensity compared with the uninvolved myocardium on T1-weighted images and of high signal intensity on T2-weighted images [7]. Magnetic resonance imaging may be limited in detecting intramural rhabdomyomas or those with an intracavitary extent of less than 0.5 cm in diameter [8]. However, as in this case, MRI has proved more accurate than echocardiography in defining the extent of the tumor and its relationship to the surrounding structures. The decision to operate was based on the MRI findings. The successful outcome indicates that MRI should be considered essential to delineate these lesions in preparation for aggressive surgical resection. In individuals without life-threatening arrhythmias or significant obstruction, echocardiography may be adequate for initial diagnosis and for follow-up, as these tumors characteristically demonstrate slow growth and may actually undergo spontaneous regression.
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Footnotes
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Address reprint requests to Dr Spindola-Franco, Department of Radiology, Montefiore Medical Center, 111 E 210th St, Bronx, NY 10467.
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References
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- Abushaban L, Denham B, Duff D. 10 Year review of cardiac tumours in childhood. Br Heart J 1993;70:166–9.[Abstract/Free Full Text]
- Spindola-Franco H, Fish BG. Radiology of the heart: cardiac imaging in infants, children and adults. New York: Springer-Verlag, 1985:639–41.
- Arciniegas E, Hakimi M, Farooki ZQ, Truccone NJ, Green EW. Primary cardiac tumors in children. J Thorac Cardiovasc Surg 1980;79:582–91.[Abstract]
- Geva T, Santini F, Pear W, Driscoll SG, Van Praagh R. Cardiac rhabdomyoma. Rare cause of fetal death. Chest 1991;99:139–42.[Abstract/Free Full Text]
- Medioni D, Pages A, Sarda P. Natural history of cardiac rhabdomyoma. Presentation of 2 cases with immunohistochemical study and review of the literature. Arch Anat Cytol Pathol 1994;42:29–34.[Medline]
- Harding CO, Pagon RA. Incidence of tuberous sclerosis in patients with cardiac rhabdomyoma. Am J Med Genet 1990;37:443–6.[Medline]
- Winkler M, Higgins CB. Suspected intracardiac masses: evaluation with MR imaging. Radiology 1987;165:117–2.[Abstract/Free Full Text]
- Rienmuller R, Lloret JL, Tiling R, et al. MR imaging of pediatric cardiac tumors previously diagnosed by echocardiography. J Comput Assist Tomogr 1989;13:621–6.[Medline]
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Abstract
Introduction
