Removal of a Neonatal Rhabdomyoma Causing Left Ventricular Outflow Tract Obstruction

Rhabdomyomas account for 45 percent of the 0.2 percent incidence rate of pediatric primary cardiac tumors (2). While many undergo involution and do not require surgical intervention, a rare few can be obstructive, as seen in this neonate’s case (3). This case demonstrates the removal of an infantile rhabdomyoma causing left ventricular outflow tract obstruction. 

At the time of the operation, the patient was a term neonate, five days old, presenting with a persistent systolic grade 3/6 murmur and a patent foramen ovale with left-to-right shunting. The bilobed neoplasm obstructed the patient’s left ventricular outflow tract, reducing blood flow and resulting in a mean gradient of 26 mmHg. Surgical risks vary depending on the infiltration of the rhabdomyoma into the ventricular septum or aortic valve, and the complexity of the operation, which can lead to longer bypass times. 

The surgical techniques began with a median sternotomy, followed by access to the rhabdomyoma through an aortotomy, extended to the noncoronary sinus for prime visualization and resection. 

The rhabdomyoma was identified on the preoperative transesophageal echocardiogram, with the smaller lobe measuring 3.5x3.7x3.7 mm, originating from the basal anterior myocardium, and the larger lobe measuring 6x8.5x11 mm prolapsing into the left ventricular outflow tract. 

A midline sternotomy was performed, and the patient was cannulated in a standard fashion. Cardiopulmonary bypass was initiated, allowing the patient to cool gradually. 

An aortotomy was made and extended into the noncoronary sinus. Stay sutures were used to allow for clear observation of the solid mass under the aortic valve leaflets. The surgeons were able to grasp and retract the mass to achieve nearly circumferential visibility. 

A fibrotic attachment to the aortic annulus was noted to be under the left coronary cusp. A suture was placed through the mass for leverage, and then it was partially resected with a scalpel. The remainder of the muscular adhesions were cut sharply with scissors. There did not appear to be any remains of the tumor attached to the musculature. Further inspection showed intact leg leaflets of the aortic semilunar and mitral valve. The surgeons then closed the aortotomy with sutures, vigorously deairing the heart before removing the cross-clamp. After a few moments of repercussions, the heart regained sinus rhythm. The pump time was 35 minutes, the cross-clamp time was 23 minutes, and there were no operative complications. 

Postoperative transesophageal echocardiogram showed no residual left ventricular outflow obstruction and mild aortic valve regurgitation. 

References

1. ElBardissi, A. W., Dearani, J. A., Daly, R. C., Mullany, C. J., Orszulak, T. A., Puga, F. J., & Schaff, H. V. (2008, May 1). Analysis of benign ventricular tumors: Long-term outcome after resection. The Journal of Thoracic and Cardiovascular Surgery. https://www.sciencedirect.com/science/article/pii/S0022522307018569?via%3Dihub
2. Sarkar, S. (2022, November 14). Cardiac rhabdomyoma. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK560609/
3. Taber, R. E., & Lam, C. R. (2019, November 11). Diagnosis and surgical treatment of intracardiac myxoma and Rhabdomyoma. The Journal of Thoracic and Cardiovascular Surgery. https://www.sciencedirect.com/science/article/pii/S0022522319326145?via%3Dihub
4. Wong, D. R., Luc, J. G. Y., Nguyen, Q., & Latham, T. B. (2023). Lateral (left–right commissural) root enlargement may reduce risk of coronary artery obstruction from transcatheter aortic valve-in-valve implantation. JTCVS Techniques, 21, 56–58. https://doi.org/10.1016/j.xjtc.2023.05.006

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