Author: Nicholas Houska, DO - University of Colorado - Children’s Hospital Colorado
A 13-year-old boy with tetralogy of Fallot and pulmonary atresia presents for right ventricle to pulmonary artery conduit replacement. Which of the following factors is a major risk for re-entry injury during repeat sternotomy?
EXPLANATION
Repeat sternotomy in pediatric cardiac surgery is associated with a variety of complications, including re-entry injury (RI) to cardiac and vascular structures, ventricular fibrillation, and venous air embolism. While the definition of re-entry injury varies, most studies categorize re-entry injuries as major or minor, with major injury typically requiring urgent initiation of peripheral cardiopulmonary bypass (CPB). Historical studies have demonstrated a five to ten percent rate of RI during repeat sternotomy, while more recent studies demonstrate a lower rate of less than two percent. Despite the low frequency of RI during repeat sternotomy, there is a significant risk of associated morbidity and mortality.
Risk factors for RI during repeat cardiac surgery should be evaluated before surgery. Additionally, efforts to mitigate injury and reduce harm after a RI should be discussed by the perioperative team. A 2009 study by Kirshbaum et al., which included one thousand repeat sternotomies for congenital cardiac surgery, revealed an overall incidence of RI as 1.3%. Risk factors for major RI resulting in hemodynamic instability, emergent transfusion, or emergent femoral cannulation included the number of repeat sternotomies and the presence of a right ventricle to pulmonary artery conduit. Of note, RI was not associated with increased operative mortality. Preoperative planning, such as diagnostic imaging, to determine the relationship of critical structures to the sternum and the status of peripheral vessels for emergent CPB initiation is often warranted. Appropriately sized and situated vascular access for the rapid administration of blood products and inotropes should be present in the event of major vascular injury. Timely access to a large volume of blood products should be arranged between the operative team and the blood bank. Elective peripheral CPB initiation before sternotomy may be prudent in some patients deemed extremely high risk for RI. For patients with a high likelihood of requiring further sternotomies, some institutions routinely place a substernal membrane made of polytetrafluoroethylene to decrease the risk of RI, though data on efficacy is limited.
Recent studies have shown that the risk of reentry injury (<2%) during repeat sternotomy has continued to decline in the last few decades. While there are few studies on risk factors for reentry injury, a retrospective study of a thousand repeat sternotomies concluded that the number of repeat sternotomies (answer A) and the presence of a right ventricular to pulmonary artery conduit are risk factors for RI.
REFERENCES
Kirshbom PM, Myung RJ, Simsic JM et al. One thousand repeat sternotomies for congenital cardiac surgery: risk factors for reentry injury. Ann Thorac Surg. 2009 Jul;88(1):158-61. doi: 10.1016/j.athoracsur.2009.03.082. PMID: 19559217.
Morales DL, Zafar F, Arrington KA et al. Repeat sternotomy in congenital heart surgery: no longer a risk factor. Ann Thorac Surg. 2008 Sep;86(3):897-902; discussion 897-902. doi: 10.1016/j.athoracsur.2008.04.044. PMID: 18721579.
Russell JL, LeBlanc JG, Sett SS, Potts JE. Risks of repeat sternotomy in pediatric cardiac operations. Ann Thorac Surg. 1998 Nov;66(5):1575-8. doi: 10.1016/s0003-4975(98)00829-7. PMID: 9875754.
Jacobs JP, Iyer RS, Weston JS, Amato JJ, Elliott MJ, de Leval MR, Stark J. Expanded PTFE membrane to prevent cardiac injury during sternotomy for congenital heart disease. Ann Thorac Surg. 1996 Dec;62(6):1778-82. doi: 10.1016/s0003-4975(96)00610-8. PMID: 8957386.
