Effect of veno-venous ultrafiltration on myocardial performance immediately after cardiac surgery in children. A prospective randomized study.

OBJECTIVES: This study sought to evaluate the effects of veno-venous ultrafiltration on myocardial contractility in children undergoing cardiopulmonary bypass (CPB) for repair of congenital heart defects. BACKGROUND: Ultrafiltration (UF) is currently used to diminish postoperative fluid accumulation following CPB in children. Previous reports indicate improvement in hemodynamics immediately after UF, but the mechanism of its action is unknown. METHODS: Twenty-three patients (ages 2 months to 9.1 years; 13 males, 10 females) underwent UF for 10 min after CPB. Twelve patients underwent UF immediately after CPB (Group A). They were studied: (1) before and (2) after CPB, (3) after UF, and (4) 10 min after UF. Eleven patients underwent UF 10 min after CPB (Group B). They were studied: (1) before and (2) after CPB, (3) after a 10-min delay before UF, and (4) after UF. Contractility was determined by the difference in the observed and predicted velocity of circumferential fiber shortening for the measured wall stress, using transesophageal echocardiography. Left ventricular wall thickness was also measured. RESULTS: There was significant improvement in contractility after UF in both groups (mean+/-SD, Group A: -0.28+/-0.13 to -0.01+/-0.21 circ/s, p < 0.05; Group B: -0.26+/-0.16 to -0.11+/-0.17 circ/s, p < 0.05). Myocardial thickness to cavity dimension decreased in both groups following UF (Group A: 0.19+/-0.04 to 0.14+/-0.03, p < 0.05; Group B: 0.18+/-0.04 to 0.14+/-0.03, p < 0.05). CONCLUSIONS: UF improves hemodynamics by improving contractility and possibly by reducing myocardial edema in children following cardiac surgery. Enhanced patient outcome after ultrafiltration may in part be due to these changes.

The large window ductus: a surgical trap.

A rare window type of patent ductus arteriosus is reported that was large (15 mm in maximal transverse dimension) but had virtually no length and hence was externally invisible. The smaller aortic isthmus (4 mm in diameter), which was intrapericardial, was mistaken for the ductus and was inadvertently clip-occluded, leading to death. After a specific diagnosis is made, the large window ductus should be patched on cardiopulmonary bypass with a transpulmonary approach.

Extrinsic airway compression secondary to pulmonary arterial conduits: MR findings.

Abnormal enlargement or malposition of any vascular structure or mass adjacent to the airway can cause extrinsic airway compression. In children with previous surgery for congenital heart disease, mass effect from prosthetic devices or alteration in the anatomic position of normal structures can lead to extrinsic airway compression. Because many children have complex medical problems after cardiac surgery, wheezing may be attributed to cardiac causes and airway compression may not be investigated. Furthermore, the distal airway compression seen in these children often is not visualized on chest radiographs. MR imaging can be useful in evaluating extrinsic airway compression in these patients. We present the MR imaging of two patients with symptomatic extrinsic airway compression secondary to pulmonary arterial conduits.

Tracheoplasty for congenital complete tracheal rings.

OBJECTIVE: To better appreciate the complex nature of the pediatric patient with tracheal stenosis due to congenital complete tracheal rings, we evaluated clinical presentation, methods of evaluation, necessity for surgical repair, associated anomalies, and outcome. DESIGN: Retrospective study. PATIENTS: Eighteen patients with long-segment tracheal stenosis due to congenital complete tracheal rings were evaluated at Cincinnati (Ohio) Children's Hospital Medical Center between 1985 and 1991. Three patients did not require surgical intervention. Fifteen patients underwent tracheoplasty with cardiopulmonary bypass through a midline sternotomy. RESULTS: The patients with congenital complete tracheal rings usually present with respiratory compromise in the first year of life. In the majority of patients, a diagnosis was made based on the symptoms and findings of an endoscopic examination with the aid of plain film roentgenography. In selected patients, computed tomography or magnetic resonance imaging was used. We evaluated symptoms, length of stenosis, type of repair, duration of intubation, and complications, as well as the mortality associated with this procedure. CONCLUSIONS: The technique of tracheoplasty has evolved at our institution, including the use of a posterior tracheal division, anterior castellated division, autologous pericardial patch grafting, and cricoid split with intubation for 7 to 21 days. We found the mortality associated with this procedure quite high at 47%, compared with previously published reports with mortality figures between zero and 77%.

Midterm results with cryopreserved allograft valved conduits from the right ventricle to the pulmonary arteries.

From 1985 to 1990, 89 patients underwent placement of 41 aortic and 54 pulmonic cryopreserved allograft valved conduits between the right ventricle and the pulmonary arteries. Six patients underwent replacement with a second allograft conduit. Median age at operation was 4.3 years, and 20 patients were infants less than 1 year of age. Conduit sizes averaged 11 mm in the conduits placed in 20 infants and 20 mm in the 75 placed in patients more than 1 year of age. There were 7 early deaths in 89 patients (7.8%, 70% confidence levels 5.4% to 11.3%) and 9 late deaths in 82 hospital survivors (11%, 70% confidence levels 8% to 15%). Actuarial survival was 81% (70% confidence levels 75% to 86%) at 33 months, and no deaths were due to conduit problems. Late reoperation was required in 13 patients (7 for conduit obstruction, 1 for conduit valve insufficiency, and 5 for nonconduit-related problems). Six of the eight reoperations were done in patients who had small (< or = 13 mm) conduits placed during infancy. Conduit failure was similar between pulmonic and aortic allografts. There were no deaths in the eight patients who required conduit reoperation. Actuarial freedom from reoperation for conduit dysfunction was 80.5% (70% confidence levels 72% to 86%) at 53 months for the entire group and 94% (confidence levels 88% to 97%) at 44 months for patients more than 1 year of age. Cryopreserved allograft conduits have good early and midterm results and are comparable to porcine xenograft conduits. Despite a likely need for replacement within 3 years, we continue to favor the use in infants of an allograft valved conduit over a xenograft Dacron conduit. The need to replace a cryopreserved allograft conduit appears similar for conduits of aortic or pulmonic origin.

Innominate artery compression of the trachea. Treatment by reimplantation of the innominate artery.

The standard treatment of innominate artery compression of the trachea has been innominate artery suspension, but the syndrome can recur when this technique is used. From October 1985 until March 1991, 29 infants and children were treated for this syndrome by innominate artery reimplantation. In all patients severe anterior vascular compression of the trachea was demonstrated preoperatively by bronchoscopy and in 17 the diagnosis was confirmed by magnetic resonance imaging scanning. Indications for operation included apneic episodes in 17 (58.6%), severe stridor in seven (24.1%), recurrent bronchopulmonary infections in four (13.8%), and exercise-induced stridor in one (3.4%). Through a median sternotomy, the innominate artery was reimplanted more proximally on the ascending aorta and to the right of the trachea. In this new position, the innominate artery no longer crosses the trachea anteriorly, and the anatomic cause of tracheal obstruction is completely eliminated. There were no early or late deaths, and 27 of the 29 patients (93%) had complete resolution of symptoms. Partial resolution of symptoms was seen in two patients (7%). Reimplantation of the innominate artery offers a unique method by which the anatomic cause of tracheal compression is eliminated. It is a safe and effective means of treating symptomatic compression of the trachea by the innominate artery.

Value of computed tomography of the lung in the management of primary spontaneous pneumothorax.

The treatment of patients with primary spontaneous pneumothorax remains controversial, since recurrence and the ultimate need for thoracotomy [corrected] cannot be predicted. In the current study, computed tomography (CT) of the lung was performed prospectively on 26 consecutive patients with primary spontaneous pneumothorax to determine whether the size and/or the number of apical blebs would correlate with recurrence and/or need for thoracotomy [corrected]. Both the number of blebs and the bleb score (calculated by the number of blebs multiplied by a numeric value assigned a range of bleb sizes) of the affected lung was significantly greater in patients with a history of recurrent pneumothorax and/or ultimate need for thoracotomy [corrected] as treatment. CT of the lung may be useful in predicting the natural history of pneumothorax.

Complement activation and lung permeability during cardiopulmonary bypass.

Pulmonary dysfunction after cardiopulmonary bypass has been attributed to the damaging effects of complement activation on the lung. To further explore this phenomenon, we measured plasma levels of activated complement components (radioimmunoassay), assessed neutrophil n-formyl-methionyl-leucyl-phenylalanine (FMLP) receptor status (radioligand saturation binding assay), and quantified pulmonary epithelial permeability as radioaerosol lung clearance of technetium 99m-labeled diethylenetriamine pentaacetic acid in a series of 8 patients undergoing cardiopulmonary bypass. Significant elevations of plasma C3adesArg, C4adesArg, and C5adesArg levels were seen just after CPB, indicating activation of both the classic and alternate complement pathways. Neutrophil activation was evident as increased expression of neutrophil FMLP surface receptors after bypass. Despite the presence of complement and neutrophil activation, increased pulmonary epithelial permeability was not seen. These data support the hypothesis that complement and neutrophil activation during cardiopulmonary bypass is not associated with acute lung injury, at least not pulmonary epithelial injury. One can therefore infer that increased pulmonary epithelial permeability in patients at high risk for and experiencing sepsis-induced and trauma-induced adult respiratory distress syndrome may be due to factors other than complement and neutrophil activation.

Innominate artery compression of the trachea: current concepts.

One common vascular anomaly that causes airway obstruction in neonates and infants is innominate artery compression of the trachea. A great deal of controversy exists regarding the effect of this anatomic variant on symptom production. Several cases are presented that demonstrate the unique features of innominate artery compression of the trachea: 1. Innominate artery compression can occur in adolescent patients. 2. Flow volume loops are an effective method of documenting airway compromise in this condition. 3. Exercise intolerance should be considered as a relative indication for surgical intervention in these patients. 4. Reimplantation of the innominate artery is a viable surgical alternative in the treatment of affected patients. 5. Telescopic bronchoscopy during surgical correction of this condition will ensure that there has been successful correction of the tracheal compression. 6. Urgent repair is advocated in patients who experience periods of apnea.

Efficacy of intraoperative transesophageal echocardiography in children with congenital heart disease.

The feasibility and potential adverse effects of using intraoperative transesophageal echocardiography (TEE) in 19 children ages 7.5 to 16 years undergoing surgical repair of a variety of congenital heart defects were evaluated. The ability of TEE to assess the adequacy of surgical repair as well as left ventricular function and wall motion abnormalities in this setting was also examined. Intraoperative transesophageal 2-dimensional and Doppler evaluation, and, in selected patients, echo-contrast and color flow imaging, were performed with either a 3.5- or 5.0-MHz phased array probe mounted within the tip of a flexible gastroscope. Probe insertion was successful in 18 of 19 patients. Fiberoptic endoscopy (9 patients) and autopsy (1 patient--cardiac donor) performed within 24 hours of surgery demonstrated no significant esophageal abnormalities. Intraoperative wall motion abnormalities were identified in 8 patients but did not persist after the operation. An adequate surgical repair was demonstrated by contrast and color flow imaging in most patients. Microcavitation was detected in 6 patients for greater than 5 minutes after a standard debubbling procedure. No patient displayed any adverse neurologic effects. It is concluded that, with the currently available probes, intraoperative TEE can be performed safely and reliably in children as young as 7.5 years of age. The procedure provides valuable information regarding wall motion abnormalities, cardiac function and the adequacy of surgical repair.

Management of a complex, posttraumatic, pelvic arteriovenous fistula with the use of cardiopulmonary bypass: case report and review of the literature.

A 34-year-old man had a posttraumatic, pelvic arteriovenous fistula (AVF) and false aneurysm of 18 years' duration. He had undergone four previous unsuccessful attempts at operative repair, the last of which almost resulted in exsanguination. After the false aneurysm was exposed, the patient was placed on cardiopulmonary bypass. Core cooling (25 degrees C) allowed the perfusion flow rates to be lowered (less than 0.5 L/min/m2) while the aneurysm was opened, thereby permitting visualization and ligation of the arteriovenous communications within the aneurysm. Total circulatory arrest was not required. There were no complications and the patient was discharged on the eleventh postoperative day. Arteriography 5 months later showed complete ablation of the AVF. We believe that cardiopulmonary bypass with hypothermia and reduced blood flow is a useful adjunct in the repair of complex AVFs and arteriovenous malformations. This technique avoids the use of total circulatory arrest, which increases the risks of air embolism and ischemic organ injury.

Vascular rings: MR imaging.

The purpose of this study was to assess the utility of MR imaging in identifying anatomic features of vascular rings. MR imaging of the thorax was performed in five consecutive children with symptoms and findings of vascular rings on barium esophagography. The diagnoses were subsequently proved at surgery and/or angiography. Preoperative definition of the anatomy was adequate and accurate in each case. Our preliminary experience with MR imaging in five patients with vascular rings suggests that this technique is an excellent alternative to angiography when further anatomic delineation of the abnormality is required.

Predictors of postoperative ventricular dysfunction in infants who have undergone primary repair of a ventricular septal defect.

By means of postoperative radionuclide angiography we identified a subset of infants undergoing primary repair of their ventricular septal defects (VSD) who had postoperative morbidity and ventricular dysfunction. Twenty-three consecutive infants undergoing repair of an uncomplicated VSD were studied. Radionuclide-determined postoperative ventricular dysfunction (VD), as defined by a left ventricular ejection fraction less than 0.30 2 to 4 hours after surgery, was correlated with clinical signs of postoperative morbidity. Six patients developed postoperative VD. Clinical correlates of VD included the use of postoperative inotropic support, increased number of postoperative intensive care days, and a low growth rate 3 months postoperatively. Potential predictors of VD were evaluated. A preoperative pulmonary-to-systemic blood flow ratio (Qp/Qs) greater than 3.0 and a pulmonary-to-systemic vascular resistance ratio (Rp/Rs) less than 0.20, taken in combination, gave a positive predictive value for VD of 100%. It is concluded that the preoperative Qp/Qs and Rp/Rs can be used to predict those infants at risk for postoperative morbidity following repair of their VSD.

A modified free-hand technique for homograft aortic valve replacement.

A modified technique for trimming and inserting the aortic homograft valve is described. This altered free-hand technique is designed to maintain normal spacial geometry of the valve apparatus in order to reduce the risk of early homograft valve incompetence.

Cryopreserved pulmonary homograft valved external conduits: early results.

Cryopreserved homograft pulmonary valves were used as a valved external conduit between the right ventricle and native pulmonary arteries in 21 patients with complex congenital heart disease. The technique used to construct the conduit was modified after incompetence of the valve was detected early in 3 of the first 9 conduits. The next 12 conduits remained competent. This experience suggests that early valve competency can be achieved if the valve is not distorted during construction of the conduit.

The effects of methylprednisolone on complement-mediated neutrophil activation during cardiopulmonary bypass.

Complement-mediated neutrophil activation (CMNA) has been implicated as an important pathophysiologic mechanism contributing to acute microvascular lung injury in the adult respiratory distress syndrome (ARDS). Using cardiopulmonary bypass (CPB) as a clinical model for complement-mediated microvascular injury, we studied the effects of methylprednisolone (MPSS) pretreatment on manifestations of CMNA in 28 pediatric patients undergoing CPB. Six patients not receiving MPSS served as controls. Results demonstrated that MPSS did not prevent complement activation as noted by 4.5- and 7.7-fold increases in plasma C3a des Arg levels during and immediately after CPB, respectively. However, detectable in vivo and in vitro manifestations of CMNA were altered. Neutropenia during CPB was attenuated to 65% of prebypass values compared with 47% in the control group. Neutrophil selective chemotactic desensitization toward C5a/C5a des Arg during the on bypass and postbypass periods was evident in the control group (0.41 and 0.76 cm specific migration, respectively) and prevented in the MPSS group (1.55 and 2.00 cm specific migration, respectively). We conclude that CMNA during CPB is ameliorated and/or prevented by MPSS pretreatment. These findings suggest that MPSS pretreatment may ameliorate complement-mediated microvascular (lung) injury in CPB and ARDS.

The cost of simultaneous surgical standby for percutaneous transluminal coronary angioplasty.

From November, 1980, to May 1985, 699 patients have undergone percutaneous transluminal coronary angioplasty of 784 lesions at our institutions. Simultaneous surgical standby was available on all cases. One hundred twenty-four patients (18%) underwent immediate myocardial revascularization; 45 (6%) were operated on because the lesion could not be dilated. Seventy-nine patients (11%) underwent immediate operation for an acute complication of angioplasty: coronary occlusion in 45, dissection in 29, coronary perforation in three, and atrial perforation in one. Fourteen patients (18%) required cardiopulmonary resuscitation en route to the operating room, and 10 patients (20%) had insertion of an intra-aortic balloon pump in the cardiac catheterization laboratory. The average time from complication to reperfusion was 87 minutes, ranging from 40 to 165 minutes. An average of 2.0 grafts per patient (ranging from one to five grafts per patient) were performed. Of those 79 patients who underwent operation for an acute complication, one died (1.3%), 31 patients (39%) had a myocardial infarction according to enzyme criteria (creatine kinase-myocardial band greater than 40 IU), and 17 patients (22%) had new Q waves on the electrocardiogram. Good results are related to minimizing the time the myocardium is ischemic. No patient in whom reperfusion was begun in less than 75 minutes had a Q wave infarction or a creatine kinase-myocardial band level greater than 40 IU. Simultaneous surgical standby is the only method allowing immediate access to surgical facilities. A standby team of eight persons and equipment were immediately available for emergency bypass grafting for an average of 3.6 hours (range 1.3 to 5.4 hours per angioplasty attempt). The patient charges for this simultaneous standby were $632.00 per angioplasty attempt, or $442,278.00 for the entire series. The actual cost of the standby was over $1,700.00 per attempt totaling $1,188,843.00 for the 699 patients. This underestimation of the cost of surgical standby has occurred in other series, because little mention has been made of this cost in the published reports on the cost effectiveness of angioplasty. In terms of time demands, over 2,500 hours were spent by surgeons standing by for the 699 attempts. Simultaneous surgical standby is the most effective means of limiting the time the myocardium is ischemic after an angioplasty complication. However, this method is costly, necessitating more of a financial and time commitment than generally anticipated. Future studies of the cost effectiveness of angioplasty should include the cost of surgical standby with accurate per-patient cost accountability.

Pinhole radionuclide ventriculography in small infants.

Radionuclide equilibrium gated ventriculograms were performed in 23 infants before and after surgery for congenital heart disease using standard parallel hole general purpose collimation followed by a pinhole collimation technique to magnify images and improve spatial resolution. A second group of nine infants had pinhole collimated gated ventriculography during cardiac catheterization for comparison with cineangiographic ejection fraction. In group I, pinhole collimation gave improved ventricular and atrial separation over general purpose parallel collimation for determination of left ventricular ejection fraction (42 of 42 studies calculable vs 37 of 42) and for right ventricular ejection fraction (36 of 37 studies calculable vs 20 of 37). In patients with transposition, pinhole technique allowed right ventricular ejection determination in nine of nine studies but in only one of nine was right ventricular ejection fraction possible by standard parallel collimation. In group II, the correlation between left ventricular ejection fraction by cineangiography and pinhole radionuclide ventriculography was excellent (r = 0.95). The correlation for right ventricular ejection fraction between cineangiography and pinhole radionuclide ventriculography was 0.82. Pinhole radionuclide ventriculography is a useful, practical clinical tool that can be used to assess ventricular function in small infants in an intensive care or outpatient setting.