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Ann Thorac Surg 1998;65:1388-1390
© 1998 The Society of Thoracic Surgeons

Cardiac Rhabdomyomas and Obstructive Left Heart Disease: Histologically but Not Functionally Benign

^a Division of Cardiovascular Surgery, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
^b Division of Cardiology, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
^c Division of Pathology, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada

Accepted for publication December 3, 1997.

Address reprint requests to Dr Black, Division of Cardiovascular Surgery, The Hospital for Sick Children, 555 University Ave, Toronto, Ont, Canada M5G 1X8
e-mail: (michael.black{at}mailhub.sickkids.on.ca)

	Abstract

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Background. Cardiac rhabdomyoma is the most common primary heart tumor in infants. Spontaneous regression of such tumors is common, particularly with smaller lesions, followed by resolution of symptoms. Based on our data on spontaneous involution, our institutional philosophy has been one of expectant management in the absence of life-threatening symptoms. However, surgical intervention sometimes is required for the extirpation of a rhabdomyoma from the left ventricular outflow tract.

Methods. A retrospective review was conducted of 30 children in whom a rhabdomyoma was diagnosed over a 27-year period.

Results. Twenty-three percent (7/30) of the children required surgical extirpation of the tumor from within their left ventricular outflow tract, although a total of 94% had left ventricular involvement. There were no deaths. To date, no child has required reexcision of tumor.

Conclusions. The natural history of rhabdomyoma is one of spontaneous regression (the 23 children who did not undergo surgical intervention are alive and continue to be followed up medically). We recommend surgical excision to alleviate acute outflow tract obstruction with reliance on the tumor’s natural history of regression to achieve long-term freedom from reoperation. Although operation has been recognized as lifesaving, we were somewhat surprised to find that greater than 20% of our pediatric population required operative intervention.

	Introduction

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Cardiac rhabdomyoma, often associated with tuberous sclerosis (51% to 86%), is the most common benign cardiac tumor in infants [1, 2]. Spontaneous tumor regression is well documented but not yet fully understood. Although the rhabdomyoma is histologically benign, it can be life-threatening secondary to mass obstruction. Much of the current literature addresses right ventricular outflow tract obstruction caused by this tumor. In this circumstance, surgical resection is possible and is made somewhat easier by the availability of a right ventriculotomy if adequate resection through the tricuspid valve is unattainable. Left ventricular outflow tract obstruction remains surgically challenging because a retrograde approach through the aortic valve is limited by the size of the neonatal annulus through which the surgeon must operate. Other, less desirable, techniques may involve an antegrade approach through the mitral valve with or without its detachment or through a ventriculotomy; both of these techniques may be more deleterious to the patient’s postoperative recovery. A rhabdomyoma rarely attaches to a semilunar or atrioventricular valve [3–5].

Over a 27-year period, 30 children with rhabdomyomas were treated at The Hospital for Sick Children in Toronto. Seven of these children required surgical extirpation of the tumor from the left ventricular outflow tract. We report the surgical results in this subset of children with rhabdomyoma.

	Material and methods

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The hospital records (cardiovascular, radiologic, and echocardiographic) of all children entered into our database over a 27-year period were reviewed. As in our previous study [6], to ensure that all patients selected actually had a rhabdomyoma, the following criteria for acceptance into the study were established: demonstration of the presence of multiple intracardiac masses with a characteristic echocardiographic or angiographic appearance, in the absence of known malignant disease; or the existence of one or more tumors in association with the neurocutaneous syndrome of tuberous sclerosis. Histologic proof of the diagnosis of rhabdomyoma no longer is considered necessary in the presence of characteristic echocardiographic findings. No child with a preoperative diagnosis of rhabdomyoma was found to have a different type of tumor at the time of operation.

	Results

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Eighty-three percent (25/30) of the children had concomitant tuberous sclerosis, and the diagnosis of cardiac rhabdomyoma was confirmed after a seizure in 30% (9/30). The rhabdomyomas were multiple in 77% (23/30) of the children. They frequently arose from the interventricular septum and approximately 30% involved the atrium. Ninety-three percent (28/30) of the children had some involvement of the left ventricle (commonly septal). Twenty-three percent of these required operation for hemodynamically significant left ventricular outflow tract obstruction (no patient required isolated right ventricular outflow tract operation). The indications for surgical extirpation in our cohort included a significant hemodynamic gradient across the left ventricular outflow tract; the mean gradient was 55 mm Hg, with a range of 28 to 93 mm Hg. The gradient was established primarily by echocardiography (Table 1). A significant subaortic fibrous ridge subsequently developed at the precise site of a resected rhabdomyoma in 1 child. The surgical specimen did not demonstrate residual tumor.

Retrograde surgical technique (example case)
In the retrograde surgical technique, cardiopulmonary bypass with moderate hypothermia was instituted, with cannulation of the ascending aorta and venae cavae. Antegrade blood cardioplegia was instilled, arresting the heart in diastole. After an aortotomy was performed, with extension into the noncoronary aortic valve sinus, gentle retraction on the aortic valve leaflets provided exposure of the firm white to gray, multilobulated mass within the left ventricular outflow tract. The tumor was secured with a 5-0 polypropylene suture (Prolene; Ethicon, Inc, Somerville, NJ) and gentle traction provided sufficient exposure to initiate the resection. The tumor was removed in several pieces to avoid inadvertent damage to surrounding vital structures. In addition, the tumor usually was too large to be extracted en masse through the aortic valve annulus. Remaining obstructive tongues of tumor were shaved from the mitral valve or ventricular septum as deemed necessary. Nonobstructive residual satellite nodules were not excised when they were difficult or dangerous to remove. Irrigation of the left ventricular outflow tract was accomplished with copious amounts of saline before aortic root closure. Air was removed from the heart, the aortic cross-clamp was removed, and rewarming was undertaken in a routine fashion.

When required, right ventricular tumors were removed through a right atriotomy (3 children). The tricuspid valve was retracted and the tumor usually could be excised without the need for a right ventriculotomy.

Antegrade surgical technique
In the antegrade surgical technique, after aortotomy and retrograde excision of the tumor, antegrade inspection of the left ventricular outflow tract was performed through the mitral valve (through an atrial septotomy when necessary). Highly mobile left ventricular apical tumors and tumors that originated from the left atrioventricular groove could be demonstrated using this approach.

	Comment

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Benign tumors such as the rhabdomyoma are capable of presenting in a variety of ways. Although the true incidence of cardiac rhabdomyoma probably has remained stable over the past decade, the rate of detection probably has increased with the introduction of routine prenatal echocardiography [6]. At least one third of our patients had their cardiac tumor diagnosed prenatally. Since our previous publication [6], an additional 21 children have been included in the analysis.

Clinical symptoms resulting from cardiac rhabdomyomas are largely a consequence of tumor size and location within the heart (ie, mechanical obstruction [inflow or outflow], decreased ventricular contractility, valvular dysfunction, rhythm disturbances). Distal thromboembolism remains a rare event, possibly related to the firmness of the tumor. Clinical observation is still the mainstay of management because the natural history of these tumors is one of gradual resolution [7, 8]. Operation is reserved for symptomatic patients with significant hemodynamic obstruction. Indications for surgical extirpation in our cohort included a significant hemodynamic gradient across the left ventricular outflow tract. All the tumors (regardless of the outflow tract gradient) functioned as a ball valve that obstructed the left ventricular outflow tract. Anatomically, the tumors hinged either from the anterosuperior aspect of the interventricular septum just beneath the aortic valve or from attachments to the region of aortic–mitral continuity (Fig 1). In all children, concern regarding acute obstruction of the left ventricular outflow tract dictated surgical removal of the tumor. Subtotal tumor excision and removal of the culprit portion was sufficient [5]. The objective was immediate relief of the significant mechanical obstruction, with resolution of the remaining tumor burden anticipated with time.

View larger version (90K): [in this window] [in a new window]   Fig 1. Serial echocardiographic views of a rhabdomyoma in a single child. Expanded preoperative view of the aortic valve showing that the leaflets were free of tumor. Color flow demonstrated turbulence within the left ventricular outflow tract starting at the level of the tumor. (B) Expanded preoperative views demonstrating that the tumor obstructed the left ventricular outflow tract. The leaflets of the mitral valve were free of tumor involvement. (C) Postoperative transesophageal echocardiogram demonstrating normal color flow across the left ventricular outflow tract with successful surgical removal of the obstructing rhabdomyoma. (AO = aorta; LA = left atrium; LV = left ventricle; NCC = noncoronary cusp; RCC = right coronary cusp; RV = right ventricle; TUM = tumor mass.)

Most children (approximately 80%) with rhabdomyomas can be observed successfully in accordance with previous recommendations. We were, however, somewhat surprised to find that greater than 20% of our pediatric population required lifesaving surgical intervention to alleviate left ventricular outflow tract obstruction [5, 6, 9]. Long-term survival is possible even when significant hemodynamic compromise is the presenting symptom. To date, none of our patients has had recurrent outflow tract obstruction or irreversible semilunar valve dysfunction.

	Addendum

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Since the completion of the manuscript, cardioscopy has been demonstrated to be a useful adjuvant in the surgical extirpation of tumors from within the left or right ventricular outflow tract [10]. Complete intracardiac visualization is provided and tumor removal can be accomplished safely with little risk to the surrounding structures.

	References

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1. Harding C.O., Pagon R.A. Incidence of tuberous sclerosis in patients with cardiac rhabdomyoma. Am J Med Genet 1990;37:443-446.[Medline]
2. Gasul B.M., Arcilla R.A., Lev M. Heart disease in children. Philadelphia: Lippincott, 1966:1086-1105.
3. Luciani G.B., Faggian G., Consolaro G., Graziani S., Martignoni G., Mazzucco A. Pulmonary valve origin of pedunculated rhabdomyoma causing moderate right ventricular outflow obstruction: surgical implications. Int J Cardiol 1993;41:233-236.[Medline]
4. 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]
5. Jacobs J.P., Konstantakos A.K., Holland F.W., II, Herskowitz K., Ferrer P.L., Perryman R.A. Surgical treatment of cardiac rhabdomyomas in children. Ann Thorac Surg 1994;58:1552-1555.[Abstract/Free Full Text]
6. Smythe J.F., Dyck J.D., Smallhorn J.F., Freedom R.M. Natural history of cardiac rhabdomyoma in infancy and childhood. Am J Cardiol 1990;66:1247-1290.[Medline]
7. Alkalay A., Ferry D., Lin B., Fink B., Pomerance J. Spontaneous regression of cardiac rhabdomyoma in tuberous sclerosis. Clin Pediatr 1987;26:532-535.[Free Full Text]
8. Farooki Z.Q., Ross R.D., Paridon S.M., Humes R.A., Karpawich P.P., Pinsky W.E. Spontaneous regression of cardiac rhabdomyoma. Am J Cardiol 1991;67:897-899.[Medline]
9. Corno A., De Simone G., Catena G., Marcelletti C. Cardiac rhabdomyoma: surgical treatment in the neonate. J Thorac Cardiovasc Surg 1984;87:725-731.[Abstract]
10. Dyamenahalli U, Black MD, Boutin C, Gow R, Freedom RM. Obstructive rhabdomyoma and univentricular physiology: a rare combination. Ann Thorac Surg (in press).

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Michael D. Black Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Black, M. D. Articles by Freedom, R. M. Search for Related Content PubMed PubMed Citation Articles by Black, M. D. Articles by Freedom, R. M.