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Catastrophic Hemorrhage during Sternal Reentry
EDITORIAL
Catastrophic Hemorrhage during Sternal Reentry Floyd D. Loop, M.D. As cardiac reoperations become more commonplace, Dobell and Jain, in their article on page 273 of this issue of The Annals, raise a timely subject that most surgeons are reticent to discuss openly. Their questionnaire, sent to more than 200 thoracic surgeons, indicates no consensus on reoperation sternotomy and elicits strong, diverse opinions concerning methods of reentry and prevention of hemorrhage. Massive bleeding caused death in 37% of patients who experienced this complication; the authors believe that this figure is probably a conservative estimate. Repeat coronary artery procedures comprise the majority of cardiac reoperations today. Ordinarily, a first coronary reoperation does not constitute a high risk for catastrophic hemorrhage. A listing of high-risk situations for reoperation includes (1)more than one reoperation; (2) ascending aortic aneurysm; (3) multiple valve disease or conditions that cause right atrial and right ventricular enlargement; (4)right ventricle-pulmonary artery conduit; and (5) previous mediastinitis with sternal osteomyelitis. Most of these circumstances command respect. In addition, previous mediastinal irradiation and cardiac cachexia contribute to the risk of reentry hemorrhage. Irradiation may cause unusually dense adherence of the aorta and heart to the sternum. The inanition found in elderly patients with chronic mitral or tricuspid regurgitation, or both, may soften the sternum so that it can be penetrated with little effort. I was surprised to learn that injury to an aortocoronary bypass graft, albeit infrequent, was fatal in 50% of the patients discussed in the questionnaire. It is likely that diffuse atherosclerosis, inadequate myocardial protection, and incomplete revascularization contributed to these deaths. A vein graft to the right coronary artery is most vulnerable during reentry. A left internal mammary artery graft also may be lacerated near the sternal edge if the pedicle is redundant or if the intact left pleura pushes it toward the midline; it also may be damaged during left ventricular mobilization. A right internal mammary artery graft anastomosed to the left coronary system is easily injured, either during the second sternotomy, or during mobilization of one or the other sternal table. The left mammary artery may be positioned away from the midline by opening the left pleural cavity widely. Covering the right mammary pedicle with the right lung provides some protection. To avoid another potential complication, the right vein graft should course over the right atrium rather than the right ventricle. From the Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44106.
271
It is our practice to prepare the femoral region in all reoperations, but for routine coronary bypass reoperations that do not fall into the high-risk categories mentioned previously, the femoral vessels are not exposed or cannulated. When the patient at high risk of sternotomy accident requires reoperation, a number of technical maneuvers are used to avoid entering underlying cardiac structures. Although summarized by Dobell and Jain, these maneuvers are worth reemphasizing: (1)appreciate that a high-risk situation exists; (2) look at the lateral chest roentgenogram to determine whether the aorta or cardiac structures are adjacent to the sternum; (3) completely expose the femoral artery and vein or, in the most hazardous situations, cannulate them before opening the sternum; (4) practice a cautious reentry; (5) retract the sternal tables upward either with rakes or by grasping the divided lower end of the sternum; (6) ask the anesthesiologist to deflate the lungs so that the mediastinal structures are pulled away from the sternum; and (7)use the oscillating saw, run at low power, and open only the outer table first. Many respondents indicated that gentle probing retrostemally may document dense sternal-cardiac adherence, but even this maneuver is not without the danger of entering a soft right ventricle with the probing finger. In patients with large or mycotic aneurysms, one may resort to a small anterolateral thoracotomy to evaluate retrosternal adherence. If hemorrhage occurs during sternotomy, two of the oldest principles of vascular surgery are prerequisites for a successful outcome: control and exposure. Control involves gentle finger compression of the bleeding site and initiation of fernorofemoral bypass. Exposure is gained by sternal mobilization before inserting the retractor. With adequate visualization, pledgeted sutures are then placed to close the defect. Aortic rents are the most serious, and large ones are nearly impossible to close. After an uneventful sternotomy, one must mobilize the left sternal table for 3 to 5 cm and the right table for approximately half that distance. In patients who have had more than one reoperation, mobilization of the innominate vein is extremely important to avoid tearing this structure as the retractor is opened. Elderly patients are particularly prone to this injury. If the vein is avulsed or completely divided, ligation is frequently a better solution than a lengthy attempt at repair. One should concentrate initially on freeing only the right side of the heart and aorta for cannulation. Inexperienced surgeons may attempt to free too much of the diaphragmatic surface of the left ventricle and cause myocardial injury before the patient is prepared for cardiopulmonary bypass. Dobell and Jain conclude that hemorrhage resulting
272 The Annals of Thoracic Surgery Vol 37 No 4 April 1984
from reoperative median sternotomy may be prevented by closing the pericardium during the first operation or by interposing mediastinal tissue or bovine pericardium (or a substitute) between the sternum and cardiac structures. In congenital heart or valve operations, bovine pericardium or a plastic substitute may be warranted, but it has not been proven that these measures make reoperation easier. Before these materials are adopted routinely, their long-term behavior and response to infection should be documented. For the routine coronary operation, I question whether pericardial closure is practical. Frank Spencer and his colleagues at New York University, who initially advocated pericardial closure, have discontinued this procedure.* In their experience, routine pericardial closure was implicated in cardiac tamponade, and it did not *Personal communication. 1983
modify adhesion formation. Also, vein grafts must be measured almost perfectly to avoid graft kinking when the pericardium is closed. My associates and I have not closed the pericardium or interposed any material between the heart and the sternum except in congenital heart patients, when reoperation is anticipated later. Our incidence of catastrophic hemorrhage is less than 1% for all cardiac reoperations and has largely been confined to those in the high-risk category. Cardiac reoperations are among the most challenging of all surgical procedures. Each one presents a different set of technical obstacles. Experience teaches us to recognize the clinical circumstances that may cause early morbidity. Life-threatening hemorrhage and myocardial injury at the outset of a procedure disrupt the natural sequence of the operation, frequently compromise the intended mission, and may culminate in a disastrous result.
Catastrophic Hemorrhage during Sternal Reentry Floyd D. Loop, M.D. As cardiac reoperations become more commonplace, Dobell and Jain, in their article on page 273 of this issue of The Annals, raise a timely subject that most surgeons are reticent to discuss openly. Their questionnaire, sent to more than 200 thoracic surgeons, indicates no consensus on reoperation sternotomy and elicits strong, diverse opinions concerning methods of reentry and prevention of hemorrhage. Massive bleeding caused death in 37% of patients who experienced this complication; the authors believe that this figure is probably a conservative estimate. Repeat coronary artery procedures comprise the majority of cardiac reoperations today. Ordinarily, a first coronary reoperation does not constitute a high risk for catastrophic hemorrhage. A listing of high-risk situations for reoperation includes (1)more than one reoperation; (2) ascending aortic aneurysm; (3) multiple valve disease or conditions that cause right atrial and right ventricular enlargement; (4)right ventricle-pulmonary artery conduit; and (5) previous mediastinitis with sternal osteomyelitis. Most of these circumstances command respect. In addition, previous mediastinal irradiation and cardiac cachexia contribute to the risk of reentry hemorrhage. Irradiation may cause unusually dense adherence of the aorta and heart to the sternum. The inanition found in elderly patients with chronic mitral or tricuspid regurgitation, or both, may soften the sternum so that it can be penetrated with little effort. I was surprised to learn that injury to an aortocoronary bypass graft, albeit infrequent, was fatal in 50% of the patients discussed in the questionnaire. It is likely that diffuse atherosclerosis, inadequate myocardial protection, and incomplete revascularization contributed to these deaths. A vein graft to the right coronary artery is most vulnerable during reentry. A left internal mammary artery graft also may be lacerated near the sternal edge if the pedicle is redundant or if the intact left pleura pushes it toward the midline; it also may be damaged during left ventricular mobilization. A right internal mammary artery graft anastomosed to the left coronary system is easily injured, either during the second sternotomy, or during mobilization of one or the other sternal table. The left mammary artery may be positioned away from the midline by opening the left pleural cavity widely. Covering the right mammary pedicle with the right lung provides some protection. To avoid another potential complication, the right vein graft should course over the right atrium rather than the right ventricle. From the Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44106.
271
It is our practice to prepare the femoral region in all reoperations, but for routine coronary bypass reoperations that do not fall into the high-risk categories mentioned previously, the femoral vessels are not exposed or cannulated. When the patient at high risk of sternotomy accident requires reoperation, a number of technical maneuvers are used to avoid entering underlying cardiac structures. Although summarized by Dobell and Jain, these maneuvers are worth reemphasizing: (1)appreciate that a high-risk situation exists; (2) look at the lateral chest roentgenogram to determine whether the aorta or cardiac structures are adjacent to the sternum; (3) completely expose the femoral artery and vein or, in the most hazardous situations, cannulate them before opening the sternum; (4) practice a cautious reentry; (5) retract the sternal tables upward either with rakes or by grasping the divided lower end of the sternum; (6) ask the anesthesiologist to deflate the lungs so that the mediastinal structures are pulled away from the sternum; and (7)use the oscillating saw, run at low power, and open only the outer table first. Many respondents indicated that gentle probing retrostemally may document dense sternal-cardiac adherence, but even this maneuver is not without the danger of entering a soft right ventricle with the probing finger. In patients with large or mycotic aneurysms, one may resort to a small anterolateral thoracotomy to evaluate retrosternal adherence. If hemorrhage occurs during sternotomy, two of the oldest principles of vascular surgery are prerequisites for a successful outcome: control and exposure. Control involves gentle finger compression of the bleeding site and initiation of fernorofemoral bypass. Exposure is gained by sternal mobilization before inserting the retractor. With adequate visualization, pledgeted sutures are then placed to close the defect. Aortic rents are the most serious, and large ones are nearly impossible to close. After an uneventful sternotomy, one must mobilize the left sternal table for 3 to 5 cm and the right table for approximately half that distance. In patients who have had more than one reoperation, mobilization of the innominate vein is extremely important to avoid tearing this structure as the retractor is opened. Elderly patients are particularly prone to this injury. If the vein is avulsed or completely divided, ligation is frequently a better solution than a lengthy attempt at repair. One should concentrate initially on freeing only the right side of the heart and aorta for cannulation. Inexperienced surgeons may attempt to free too much of the diaphragmatic surface of the left ventricle and cause myocardial injury before the patient is prepared for cardiopulmonary bypass. Dobell and Jain conclude that hemorrhage resulting
272 The Annals of Thoracic Surgery Vol 37 No 4 April 1984
from reoperative median sternotomy may be prevented by closing the pericardium during the first operation or by interposing mediastinal tissue or bovine pericardium (or a substitute) between the sternum and cardiac structures. In congenital heart or valve operations, bovine pericardium or a plastic substitute may be warranted, but it has not been proven that these measures make reoperation easier. Before these materials are adopted routinely, their long-term behavior and response to infection should be documented. For the routine coronary operation, I question whether pericardial closure is practical. Frank Spencer and his colleagues at New York University, who initially advocated pericardial closure, have discontinued this procedure.* In their experience, routine pericardial closure was implicated in cardiac tamponade, and it did not *Personal communication. 1983
modify adhesion formation. Also, vein grafts must be measured almost perfectly to avoid graft kinking when the pericardium is closed. My associates and I have not closed the pericardium or interposed any material between the heart and the sternum except in congenital heart patients, when reoperation is anticipated later. Our incidence of catastrophic hemorrhage is less than 1% for all cardiac reoperations and has largely been confined to those in the high-risk category. Cardiac reoperations are among the most challenging of all surgical procedures. Each one presents a different set of technical obstacles. Experience teaches us to recognize the clinical circumstances that may cause early morbidity. Life-threatening hemorrhage and myocardial injury at the outset of a procedure disrupt the natural sequence of the operation, frequently compromise the intended mission, and may culminate in a disastrous result.