Ann Thorac Surg 1998;65:835-837
© 1998 The Society of Thoracic Surgeons
Case Reports
Obstructive Rhabdomyoma and Univentricular Physiology: A Rare Combination
Umesh Dyamenahalli, MD,
Michael D. Black, MD,
Christine Boutin, MD,
Robert M. Gow, MB, BS,
Robert M. Freedom, MD
Division of Cardiovascular Surgery, The Hospital for Sick Children and The University of Toronto, Toronto, Ontario, Canada
Division of Cardiology, The Hospital for Sick Children and The University of Toronto, Toronto, Ontario, Canada
Accepted for publication October 16, 1997.
Dr Black, Division of Cardiovascular Surgery, The Hospital for Sick Children, 555 University Ave., Toronto, ON, Canada M5G 1X8 (e-mail: michael.black@mailhub.sickkids.on.ca).
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Abstract
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We report the successful excision of a large left atrial rhabdomyoma producing complete obstruction of both inflow and outflow to the left ventricle. Systemic perfusion was dependent on anterograde ductual flow. The resultant univentricular physiology was initially managed medically, with spontaneous tumor regression contemplated as a means of possible long-term "cure." Failure to achieve hemodynamic stability compelled urgent surgical excision. This neonate was successfully discharged home with an in-series biventricular circulation.
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Introduction
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Cardiac rhabdomyomas are the most common benign cardiac tumor in infancy and are associated with tuberous sclerosis in 51% to 86% of patients [1]. Spontaneous tumor regression is well documented; however, the mechanism is not fully understood. In general, surgical resection when required remains rewarding. Although rhabdomyomas are histologically benign, they may cause life-threatening arrhythmias or significant hemodynamic obstruction [2].
Obstructive left-sided rhabdomyomas remain a surgical challenge. A retrograde approach via the aortic valve is hampered by the limited size of the aortic valve annulus (5 to 7 mm in the neonate). Less desirable approaches are antegrade via the mitral valve with or without detachment of a valve leaflet, or via a left ventriculotomy. Rarely does the tumor attach to a semilunar or atrioventricular valve requiring either repair or replacement [3].
A 39-week gestation, 3.8-kg neonate born by emergency cesarian section remained cyanosed and with refractory supraventricular tachyarrhythmias. A 12-lead electrocardiogram revealed preexcitation with a delta wave axis indicating an accessory pathway between the left lateral and the left anterior positions [4]. Echocardiographic analysis demonstrated (1) a large left atrial mass measuring 1.7 x 1.6 mm arising from the atrioventricular groove with possible adherence to the posterior mitral valve apparatus, (2) near-total obliteration of mitral inflow, (3) absence of anterograde aortic flow, (4) retrograde ascending aortic blood flow, and (5) mild aortic regurgitation, possibly related to the tumor’s mass effect. The possibility of circumflex coronary arterial compression was entertained based on the unexpected finding of significant left ventricular dysfunction. A large unrestrictive atrial septal defect with a left-to-right shunt and patent ductus arteriosus with a right-to-left shunt permitted survival. A trial of medical management failed with evidence of progressive systemic hypoperfusion. Urgent tumor excision was deemed necessary.
Cardiopulmonary bypass with moderate hypothermia was established via the ascending aorta and venae cavae. Manual cardiac compression and intravenous administration of adenosine were required for hemodynamic compromise due to runs of supraventricular tachycardia. Anterograde sanguineous cardioplegia was introduced, arresting the heart in diastole. A right atriotomy was performed with the caval snares tightened. Via an enlarged patent foramen ovale, the left atrium was exposed and examined. A firm, white to grey multilobulated mass was identified and, as demonstrated by the preoperative echocardiogram (Fig 1), was found adherent to the posterolateral region of the atrioventricular groove. External examination revealed the tumor mass to be without evidence of circumflex arterial involvement.
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Preoperative echocardiogram demonstrating enormous size of obstructing rhabdomyoma. Note near-total left ventricular (inflow and outflow) obstruction. (AO = aorta; LA = left atrium; LV = left ventricle.)
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The tumor was secured with a 5-0 silk suture, and gentle traction provided sufficient exposure to initiate resection. The tumor was removed in several large pieces, being too large to be extracted en masse via the atrial septum. The mitral valve apparatus came into view. The anterior leaflet was completely free of tumor. The posterior leaflet required partial separation from the tumor mass. Tumor resection stopped flush with the left atrium. Nonobstructive residual satellite nodules were not excised from within the left ventricular apex or right ventricular outflow tract as imaged preoperatively. Irrigation of the left ventricular cavity was accomplished with copious amounts of saline solution before closure of the atrial septum. A well-developed septum primum was primarily sewn to the fossa ovalis to close the atrial defect. Deairing of the heart, removal of the aortic cross-clamp, and rewarming proceeded as per routine. Normal sinus rhythm intermixed with supraventricular tachycardia resumed.
A second pump run was required to address the gross central mitral insufficiency that was evident from an intraoperative echocardiogram. During the second pump run a DeVega-type posterior mitral annuloplasty was carried out over a 12-mm Hegar dilator. The annulus was successfully reduced from 19 to 12 mm with a significant reduction in the amount of mitral regurgitation (severe to mild plus) (Fig 2).
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Intraoperative echocardiogram demonstrating lack of coaptation of mitral valve leaflets due to gross annular dilatation (solid arrow).
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Postoperatively, this neonate had persistent supraventricular tachycardia, which initially was controlled by the intravenous administration of amiodarone up to 10 mg · kg-1 · day-1 and later with the addition of propafenone (oral amiodarone at 7.5 mg · kg-1 · day-1 and oral propafenone at 320 mg · kg-1 · m-2. Both narrow and rate-related broad complex left bundle-branch tachyarrhythmias were evident. At 3 months’ follow-up she continues to thrive, with only mild mitral valve regurgitation and the occasional short runs of supraventricular tachycardia seen on Holter monitoring.
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Comment
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Benign tumors such as rhabdomyomas are capable of presenting in a variety of ways. Although the true incidence of cardiac rhabdomyoma has likely remained stationary within the last decade, detection rates likely have increased with the introduction of routine prenatal echocardiography [1].
Clinical symptoms resulting from cardiac rhabdomyomas are largely a consequence of tumor size or location within the heart (ie, mechanical obstruction [inflow or outflow], decreased ventricular contractility, valvular dysfunction, or rhythm disturbances). The univentricular physiology resulting from both left inflow and outflow tract obstructions was likely a late fetal event as evidenced by the well-developed left ventricle. The tumor mass originated from the left atrioventricular groove and progressively enlarged until near-total obstruction to left ventricular inflow was present. Multiple rhabdomyomas were found in 77% (23/30) of children followed up over the previous 27 years at our institution and frequently arise from the interventricular septum, with only 30% involving the atrium. Ninety-three percent (28/30) of children at our institution had some involvement of their left ventricle (commonly septal), but we have not previously seen a child with such an unusual physiologic presentation [5].
Clinical observation continues to remain the mainstay of management because the natural history of these tumors is one of gradual resolution [1]. Operation has been reserved for symptomatic patients with significant hemodynamic obstruction. Subtotal excision of any individual tumor with removal of the culprit portion is ample management. The objective therefore should remain the immediate relief of the significant mechanical obstruction, with the resolution of the remaining tumor burden being anticipated with time. Resolution of the arrhythmias is also expected. Future surgical management of tumors that are difficult to reach will likely use a combination of approaches including minimally invasive cardioscopic techniques to aid in both tumor location and resection [6].
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References
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- Smythe JF, Dyck JD, Smallhorn JF, Freedom RM Natural history of cardiac rahabdomyoma in infancy and childhood. Am J Cardiol 1990;66:1247-1290.[Medline]
- Bosi G, Linntermans JP, Pellegrino A, Saluto-Moreolo G, Vliers A The natural history of cardiac rhabdomyoma with and without tuberous sclerosis. Acta Paediatr 1996;85:928-931.[Medline]
- Giamberti A, Giannico S, Squitieri C, et al. Neonatal pulmonary autograft implantation for cardiac tumor involving aortic valve. Ann Thorac Surg 1995;59:1219-1221.[Abstract/Free Full Text]
- Gallagher JJ, Pritchestt ELC, Sealy WC, Kasell J, Wallace AG The preexcitation syndromes. Prog Cardiovasc Dis 1978;20:285-327.[Medline]
- Black MD, Kadletz M, Smallhorn J, Coles JC, Williams WG, Freedom RM. Pediatric cardiac rhabdomyomas and obstructive left heart disease: histologically but not functionally benign. Presented at The Second World Congress of Pediatric Cardiology and Cardiac Surgery, Honolulu, HI, May 11–15, 1997.
- Proceedings of the 21st Century Cardiac Surgical Society Meeting, Newport Beach, CA, Feb 27–March 2, 1997.
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Abstract
Introduction
