Prolonged Open Sternotomy After Pediatric Open Heart Operation: Experience With 113 Patients

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1 Prolonged Open Sternotomy After Pediatric Open Heart Operation: Experience With 113 Patients Vladimir Alexi-Meskishvili, MD, Yuguo Weng, MD, Frank Uhlemann, MD, Peter E. Lange, MD, PhD, and Roland Hetzer, MD, PhD Departments of Cardiothoracic and Vascular Surgery and Pediatric Cardiology, German Heart Institute Berlin, Berlin, Germany Between April 1990 and November 1993, 1,252 open heart operations were performed in infants and children with congenital heart defects. Prolonged open sternotomy was used in 113 patients (9%) in 10 surgical categories. Thirtysix of these children (32%) were infants and 43 (38%) were newborns. Twenty-four patients (21%) had undergone operation previously; 3 newborns had been treated with extracorporeal membrane oxygenation before the operation. The patients were grouped according to indications for prolonged open sternotomy as follows: group I, 31 patients with squeezed (large) heart syndrome (1 death); group II, 14 patients with hemodynamic instability after sternal approximation (2 deaths/14.2%); group III, 35 patients with low output state after bypass (17 deaths/48.5%); group IV, 21 patients with extracorporeal circulatory assist devices (15 deaths/71.4%); group V, 3 patients with severe arrhythmias (no deaths); and group VI, 9 patients with atypical tamponade that necessitated reopening the sternum in the intensive care unit (6 deaths/66.6%). Overall mortality was 36.2% (41 patients). Four group IV patients were weaned successfully from extracorporeal membrane oxygenation and heart trans- plantation was performed successfully on two others. All but one of the deaths occurred before delayed sternal closure. After hemodynamic stabilization was achieved, the sternum was closed in all 72 surviving patients with absorbable sutures (in 86% within the first 6 days after operation). In 50 patients (69% of survivors) pericardial substitution with a polytetrafluoroethylene membrane was performed. One newborn with mediastinal infection after extracorporeal membrane oxygenation was treated successfully with retrosternal drain and suction lavage. Prolonged open sternotomy is an effective method in infants and children with severe but temporary hemodynamic instability after open heart operation. The need for circulatory assist devices, the development of low cardiac output syndrome after bypass, and the necessity of reopening the sternum in the intensive care unit were high risk factors. Using absorbable sutures for delayed sternal closure and pericardial substitution with a polytetrafluoroethylene membrane did not increase the risk of mediastinal infection significantly. (Ann Thorac Surg 1995;59:379-83) D espite improvements in surgical methods and intraoperative and postoperative care, severe hemodynamic disturbances occur in a significant number of pediatric patients after correction of congenital heart defects, usually shortly after cardiopulmonary bypass. Mortality in such cases is high, approaching 35% [1]. Today, prolonged open sternotomy (POS) is a wellestablished procedure that aids in preventing and managing low cardiac output state and atypical pericardial tamponade while decreasing the risk of early coronary compression after arterial switch operation and offsetting the negative effects of cardiac, chest, or pulmonary edema in adult and pediatric patients after open heart operation 2-7]. This article presents the results of using POS, here defined as leaving the sternum open longer than 24 hours after an operation, and delayed sternal closure (DSC), defined as subsequently closing the sternum after POS Accepted for publication Sep 20, Address reprint requests to Dr Alexi-Meskishvili, Department of Cardiothoracic and Vascular Surgery, German Heart Institute Berlin, Augustenburger Platz 1, D Berlin, Germany. [8], on 113 pediatric cardiac operation patients at the German Heart Institute Berlin. Patients and Methods Between April 1990 and November 1993, 1,252 open heart operations were performed in pediatric patients at the German Heart Institute Berlin. One hundred thirteen (9.1%) had POS including 43 newborns (38%), 36 infants (32%), and 34 children (30%) between the ages of I and 14 years. The incidence of POS was 19% in newborns, 11.3% in infants, and 4.3% in older children (226, 318, and 708 open heart operations, respectively) (Fig 1). Patients who had POS were divided into 10 surgical categories. The overall incidence of POS was 14.4%, whereby it was performed significantly more often after complex cardiac operation than after simpler procedures (eg, after correction of ventricular septal defect) (Table 1). Twenty-four patients with POS had undergone operation previously and 3 newborns with total anomalous pulmonary venous drainage were treated preoperatively with extracorporeal membrane oxygenation (ECMO). Right ventricular outflow tract reconstruction with ho by The Society of Thoracic Surgeons /95/$ (94)

2 380 ALEXI-MESKISHVILI ET AL Ann Thorac Surg PROLONGED OPEN STERNOTOMY 1N CHILDREN 1995;59: =" o =E z 200 o clmo,1too < ly >ly Age Fig 1. Incidence of prolonged open sten~otomy in different age groups. (n - number of operations.) mografts was performed in 13 patients. Peritoneal dialysis was used postoperatively in 22 infants. All operations were performed through median sternotomy and included bicaval cannulation and hypothermic cardiopulmonary bypass. Cold potassium-free cardioplegia was used for myocardial protection. Six indications for POS were observed (Table 2). Excessive bleeding was not an indication for POS as reported by others [9]. After the decision was made to leave the sternum open, the sternal edges were split open using an edge-cut disposable 2-mL syringe or a piece of adult (30F) thoracic drainage tube [8]. A sheet of Silastic (Dow Corning Corp, Midland, MI) or Ethi-Touch-Patch (Ethicon, Somerville, NJ) was tailored to the shape of the median sternotomy incision and attached to the skin edges with continuous monofilament sutures. The sternal wound dressing was changed daily during the postoperative period. The following antibiotic protocol was used in all patients: a combination of cephalosporine (cefotaxim), acylaminopenicillin (piperacillin), and glycopeptide (teicoplanin) antibiotics were administered intravenously in the operating room and continued during the intensive care period. Glycopeptide was usually discontinued 24 hours after sternal closure and the other two antibiotics 3 to 4 days later. Delayed sternal closure was performed on 72 patients (63.7%). Indications for DSC were cardiopulmonary stability, negative fluid balance, and absence of significant systemic infection. The procedure was performed in the operating room under general anesthesia. First, the skin was prepared with polividon-iodine-propanol solution, the patch removed, and tissue cultures taken. All clots were removed, debridement performed, and the pericardial cavity irrigated with warm normal saline solution. Subsequently, the monitoring lines were removed and drainage tubes were replaced with new ones. The sternal edges were approximated with interrupted absorbable sutures (Vicryl; Ethicon), the fascia closed with continuous suture (Vicryl), and the skin closed with interrupted monofilament sutures. Continuous mediastinal irrigation was not used. The paired t test was used to compare the different groups. Results Mortality Postoperative mortality in the 113 patients with POS was 36.2% (41 patients), which was significantly higher than in patients with primary sternal closure (Table 1). Mortality was higher (48.5%) in patients with low cardiac output state after cardiopulmonary bypass, in patients who were supported postoperatively with circulatory assist devices (71.4%), and in patients with atypical tamponade that necessitated reopening the sternum in the intensive care unit (66.6%) (Table 2). The mortality in Table 1. Surgical Categories, Incidence of Prolonged Open Sternotomy, and Mortality No. of No. and No. of PSCs Incidence POSs Surgical Categories Performed of Deaths Performed No. and Incidence Incidence of POS of Deaths (%) TGA + VSD (ASO) 80 3 (3.7%) 31 9 (29%) 27.9 TF, DORV + PS, VSD + PA (5.5%) 21 9 (42.8%) 10.5 CAVSD 88 2 (2.3%) 16 5 (31.2%) 15.4 TAPVC (41.6%) ALCAPA Univentricular heart variants 34 1 (3.0%) 8 4 (50%) 19.0 LVOTO (40%) 10.6 VSD (60%) 2.9 Truncus arteriosus 16 4 (25%) Misc. (HLH$, central shunt, CAVSD-TF, (29%) 5 4 (80%) 9.4 re-op after ASO, IAA) Total (5.4%) (36.2%) 14.4 ALCAPA = anomalous origin of the left coronary artery from the pulmonary artery; ASO - arterial switch operation; CAVSD - complete artrioventricular septal defect; DORV = double outlet right ventricle; HLHS = hypoplastic left heart syndrome; IAA ~ interrupted aortic arch; LVOTO - left ventricular outflow tract obstruction; PA pulmonary atresia; POS prolonged open sternotomy; PS = pulmonary stenosis; PSC - primary sternal closure; TAPVC total anomalous pulmonary venous connection; TGA - transposition of the great arteries; TF - Tetralogy of Fallot; VSD = ventricular septal defect.

3 Ann Thorac Surg ALEXI-MESKISHVILI ET AL ;59: PROLONGED OPEN STERNOTOMY IN CHILDREN Table 2. Indication and Mortality in Patients with Prolonged Open Sternotomy Group Indication for POS Number of Patients Deaths Mortality I Squeezed (large) heart syndrome % II Hemodynamic instability after temporary sternal % approximation III Low cardiac output state after CPB % 1V ECMO, LVAD, BVAD % (nonconventional cannulation) V Severe arrythmia (Repeated ventricular fibrillation, 1 patient) (Persistent supraventricular tachycardia, 2 patients) VI Atypical tamponade % (sternum reopened in the ICU) Total % BVAD biventricular assist device; CPB ~ cardiopulmonary bypass; ECMO = extracorporeal membrane oxygenation; ICU = intensive care unit; LVAD - left ventricular assist device. patients who were supported with circulatory assist devices was 2.5 times higher than in patients who were not (71.4% compared with 28.2%). Group 1V included 6 long-term survivors; cardiac transplantation was performed in 2 of them. Causes of death included low cardiac output (26 patients), which was observed preoperatively and persisted postoperatively in 5 patients, fixed high pulmonary arterial resistance (5 patients), multiorgan failure (4 patients), and brain death, intracranial hemorrhage, ventricular fibrillation, pulmonary embolism, central aortopulmonary shunt thrombosis, and bleeding (6 patients). Circulatory assist devices were used in 15 of the 41 patients who subsequently died. Patient age, aortic cross-clamp time, and bypass time exhibited no correlation with mortality. Mortality in newborns, infants, and in older children was 35.4%, 37%, and 38.2%, respectively (p > 0.05). POS bypass time (mean ± standard error of the mean) was 143 ± 30 minutes in survivors compared with 134 ± 40 minutes in nonsurvivors, whereas aortic crossclamp times were minutes and 67 ± 29 minutes, respectively (p > 0.05). The sternum was closed during the first 24 hours after operation in 2 patients, on the second day in 8, on the third day in 24, after 4 to 6 days in 28, and after 7 to 16 days in the remaining 10 patients (Fig 2). In 50 of 72 patients pericardial substitution with a polytetrafluoroethylene membrane (Gore-Tex; W.L. Gore, Flagstaff, AZ) was performed during DSC to prevent sternotomy complications in the event of subsequent operation (Fig 2). As observed earlier, using this membrane after surgical correction of congenital heart diseases does not increase the risk of mediastinitis [10]. Routine microbiological examinations of mediastinal and pericardial specimens taken from all 72 patients during DSC were negative except in I newborn who was supported with ECMO for 163 hours after an arterial switch operation. Mediastinitis in this patient was treated successfully with retrosternal irrigation and suction drainage for 7 days. No other mediastinal or superficial wound infections were observed in the other patients. It was necessary to perform rethoracotomy in 5 patients I to 15 days after DSC to stop bleeding (1 patient), to correct epicardial pacemaker electrodes (1 patient), and to drain fluid accumulation in the pericardial cavity (3 patients). One newborn died 3 days after DSC due to necrotizing enterocolitis. Comment Open heart operation in newborns and infants is often associated with significant hemodynamic disturbances shortly after cardiopulmonary bypass [1, 2, 4, 11]. In such patients surgeons frequently observe a discrepancy between an enlarged heart and the pericardial cavity [6, 7, 12]. Sternal closure after complex cardiac repairs causes a reduction in mean arterial pressure and cardiac output and is associated with significant cardiopulmonary compromise [4, 13] (Fig 3). These changes can be aggravated postoperatively from swelling and edema of myocardium or from an increase in right ventricular end diastolic dimension in patients with pulmonary regurgitation or pulmonary hypertensive crisis, thus leading to atypical tamponade caused by a significant discrepancy between heart size and mediastinal space after sternal closure [14, 151. Riahi and colleagues [16] were the first to describe cardiac compression in an adult patient caused by the disproportion between heart size and mediastinal space after cardiopulmonary bypass. Ott and colleagues [17] presented the first successful adult and infant cases and introduced the DSC procedure. Bex and colleagues [18] reported the first successful use of POS and DSC, which was performed in a newborn patient. 50 ~a ~ 2o E z 10- O Fig 2. Time of delayed sternal closure in 72 patients and percentage of patients in whom pericardial substitution was performed with surgical membrane.

4 382 ALEXI-MESKISHVIL1 ET AL Ann Thorac Surg PROLONGED OPEN STERNOTOMY IN CHILDREN 1995;59: HR AJ J 63 A 55 B AP 44 4o 3~ 33 PAP E cv Fig 3. Hemodynamic changes before (A) and after (B) temporary sternal approximation in a 2-month-old infant after correction of complete atrioventricular septal defect (group II). Note the decrease in systemic arterial pressure (AP) and the increase in diastolic pulmonary arterial pressure (PAP) and central venous pressure (CVP) after sternal approximation. (HR = heart rate.) Prolonged open sternotomy prevents development of atypical tamponade and contributes to more effective management of hemodynamic disturbances during the early postoperative period. The incidence of POS varies according to the type of operation and the patient's age. In adults the incidence of POS is between 1.2% and 3% [3, 5, 9, 19, 20]. Prolonged open sternotomy is sometimes used in patients who are supported by extracorporeal circulatory assist devices (nonconventional cannulation) and in patients who undergo intrathoracic balloon pump insertion through the ascending aorta [19]. The incidence of POS in pediatric patients is higher than in adults, approaching 62% in newborns [2] and 10% in infants [7]. Some surgeons routinely leave the sternum open in newborns with hypoplastic left heart syndrome after a Norwood operation, thus "decreasing the incidence of labile oxygen saturations and low output state" [6]. In our group of 1,252 open heart operations the incidence of POS increased from 4.5% in 1991 to 15% in 1993, thus reflecting more liberal use of this procedure in pediatric patients. It is difficult to define "squeezed" heart syndrome, which almost always occurs in newborn patients after prolonged cardiopulmonary bypass and complex operation. This syndrome, which is not always associated with low cardiac output state, optically manifests itself as an enlarged heart that does not permit primary sternal closure without compromising heart function [2, 7]. These patients (our groups I and II) have better prognoses because, as cardiac size decreases, sternal closure can be performed without difficulty. Delayed sternal closure was not very effective in the group of patients with low output state after cardiopulmonary bypass. The mortality of patients with POS in this study was much higher than in others after primary sternal closure (Table 1). In a survey of the medical literature (353 patients from 14 series published between 1978 and 1994) the mortality of adult patients who underwent POS was 41.1% (145 deaths). In a pediatric group (221 patients/16 publications from the same time period) there were 55 deaths (25%), thus reflecting different indications for POS in adults and children. Generally, POS was performed in adult patients to treat severe low cardiac output after cardiopulmonary bypass [3, 5, 9] and in pediatric patients primarily to prevent the development of atypical tamponade after complex congenital heart operation [2, 4, 6, 7]. The use of circulatory assist devices increased the probability of death despite POS. We observed mortality rates in patients with POS with or without circulatory assist devices (66.5% and 28.5%, respectively) similar to those reported in adult patients (71.4% and 28.2%) by Furnary and colleagues [5]. Patients who underwent resternotomy in the intensive care unit had a high mortality rate [2, 7]. This reflected attempts to save patients who probably had end stage hemodynamic disturbances. After the patient's condition is stabilized, sternal closure can be performed safely [2, 6-8, 19]. Only one patient in this group died after DSC. Empirically a high incidence of wound infections might be expected in patients with POS; however, this was not supported by published data. In an evaluated series of 353 adult patients with POS, there were 7 cases (1.98%) of deep wound infections. In 221 pediatric patients there were 4 cases (1.8%) of mediastinitis. The incidence of mediastinitis in our patient group was 0.8%, represented by a newborn who was supported with ECMO for 163 hours after an arterial switch operation. The incidence of mediastinitis in 1,139 pediatric patients who underwent open heart operation with primary sternal closure between 1990 and 1993 at the German Heart Institute Berlin was 0.08% (1 patient) compared with 0.8% in patients with POS. This was not higher than the general incidence of mediastinitis (0.4% and 2.2%) after pediatric open heart operation [21]. When performing DSC, we routinely use absorbable sutures (Vicryl) for sternal closure in all pediatric patients. Moreover, in our experience, the use of Gore-Tex surgical membrane, which we used in almost 70% of our patients during DSC, does not increase substantially the probability of developing deep wound infections. In conclusion, prolonged open sternotomy is an effective method in infants and children with severe but temporary hemodynamic instability after open heart operation. The need for circulatory assist devices, the development of low cardiac output syndrome after bypass, and the necessity of reopening the sternum in the intensive care unit were high risk factors. Using absorbable sutures for DSC and pericardial substitution with Gore- Tex surgical membrane did not significantly increase the risk of mediastinal infection. We thank Jonathan Davis for providing editorial assistance in the preparation of the manuscript.

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