Repair of long-segment tracheal stenosis in infancy

Long-segment stenosis of the trachea in infancy is a considerable surgical challenge because the infants are generally extremely ill and the airway is small. The optimal type of repair is not clearly defined. This report summarizes our experience with rib cartilage tracheoplasty done with cardiopulmonary bypass. Six patients underwent repair of long-segment tracheal stenosis between September 1987 and September 1994. The mean age was 14 weeks (range 1 to 58 weeks). Patients had stenosis of at least 70% of the tracheal length, typically with complete cartilaginous rings. In all patients stenosis was repaired by placement of a section of rib cartilage as an augmentation patch into the anterior surface of the trachea, which had been incised through the entire length of the stenosis. To avoid distal airway intubation, we used cardiopulmonary bypass for all procedures, with a mean bypass duration of 110 minutes (range 54 to 175 minutes). Mechanical ventilation was required for a median of 11 days after the operation (range 7 to 81 days), and the median postoperative hospital stay was 17 days (range 12 to 180 days). All patients are long-term survivors. Complications included the need for extracorporeal membrane oxygenation to treat ventricular dysfunction in one patient and graft dehiscence requiring revision of the distal graft in another. The latter patient has required several treatments with a bronchoscope for removal of granulation tissue. All other patients are free of symptoms and have normal growth with a mean follow-up of 4.7 years (range 5 months to 7.6 years). We conclude that rib cartilage tracheoplasty for long-segment tracheal stenosis provides excellent results in short and intermediate follow-up. In addition, the use of cardiopulmonary bypass allows an unobstructed view of the tiny infant airway and thus permits a precise repair.

Single lung transplantation for pulmonary hypertension. Single institution experience in 34 patients

BACKGROUND

The present study considered the uniformity and durability of the cardiopulmonary response to single lung transplantation in patients with severe pulmonary hypertension, as well as its effect on length and quality of survival.

METHODS AND RESULTS

Thirty-four patients with pulmonary hypertension underwent evaluation, single lung transplantation, and follow-up assessment between November 1, 1989, and June 1, 1994. Operative survival for the entire group of patients was reasonable, with 91% (31 of 34 patients) surviving and being discharged from the hospital following transplantation. The actuarial survival for these 34 patients at 1-, 2-, and 3-year follow-up was 78%, 66%, and 61%, respectively. In the subgroup of 24 patients with primary pulmonary hypertension (PPH), 96% (23 of 24) were successfully discharged from the hospital after transplantation. The actuarial survival for this isolated PPH subgroup at 1-, 2-, and 3-year follow-up was 87%, 76%, and 68%, respectively. The uniform, early posttransplant normalization of pulmonary vascular resistance and right ventricular ejection fraction appears to persist throughout the 4-year follow-up period. Despite a high prevalence of bronchiolitis obliterans, the majority of survivors remain in New York Heart Association functional class I or II and are employed.

CONCLUSIONS

Single lung transplantation can be performed in patients with end-stage pulmonary vascular disease with reasonable expectations for a relatively low operative mortality; immediate, complete, and durable amelioration of pulmonary hypertension and right ventricular failure; and optimal use of limited donor organ supply.

Lung transplantation for congenital pulmonary vein stenosis

BACKGROUND

Congenital pulmonary vein stenosis is a uniformly fatal disease when left untreated. Transcatheter techniques (for example, balloon dilation and stent placement) have proved to be only temporizing measures, and previous surgical attempts at treatment of this entity have provided little improvement and few survivors.

METHODS

Over the last 4 years, 6 patients with congenital pulmonary vein stenosis have been treated at our institution, 3 of whom underwent bilateral sequential lung transplantation.

RESULTS

The 3 patients who underwent bilateral lung transplantation are alive and well 6 to 24 months after transplantation. The other 3 died of complications of the disease before donor lungs became available.

CONCLUSIONS

Making the diagnosis of congenital pulmonary vein stenosis requires a high index of suspicion, and referral for lung transplantation should be made as soon as the diagnosis is reached. Lung transplantation has resulted in good-quality short to medium-term survival for 3 patients with this otherwise untreatable disease.

Deletion within chromosome 22 is common in patients with absent pulmonary valve syndrome

Interstitial deletions in chromosome 22 and features associated with CATCH-22 syndrome have been reported in patients with conotruncal congenital heart anomalies. Absent pulmonary valve syndrome is characterized by absent or rudimentary pulmonary valve cusps, absent ductus arteriosus, conoventricular septal defect, and massive dilation of the pulmonary arteries. Because absence of the ductus arteriosus is a key element in the pathogenesis of this syndrome and aortic arch malformations are frequently seen in patients with CATCH-22 syndrome, we hypothesized that patients with absent pulmonary valve syndrome would have a high incidence of deletions in the critical region of chromosome 22. Eight patients with absent pulmonary valve syndrome were studied. Metaphase preparations were examined with fluorescent in situ hybridization of the N25 (D22S75) probe to the critical region of chromosome 22q11.2. Deletions were detected in 6 of 8 patients. The presence of deletions in chromosome 22 in most of the patients we have examined with a diagnosis of absent pulmonary valve syndrome supports a specific genetic and embryologic mechanism involving the interaction of the neural crest and the primitive aortic arches as one cause of congenital absence of the pulmonary valve.

Estimation of total lung capacity from chest radiography and chest CT in children: comparison with body plethysmography

OBJECTIVE

The purpose of this study was to evaluate two methods of estimating lung volume using chest radiographs and one using chest CT in children. Estimates made with these techniques were compared with total lung capacity calculated with body plethysmography.

MATERIALS AND METHODS

CT scans and posteroanterior and lateral radiographs of the chest were obtained in 21 children (14 girls and seven boys) for follow-up evaluation after lung transplantation. Lung volume was measured by CT using a previously validated technique of tracing the margins of the lungs on each axial CT scan. Two methods were used to estimate lung volume on chest radiographs: a technique previously described in adults and children that requires 21 measurements on posteroanterior and lateral radiographs, and a modification of a simplified technique previously reported in adults that uses only two measurements on a posteroanterior radiograph alone. Estimated lung volumes from CT and from both methods using chest radiographs were compared with total lung capacity determined from body plethysmography using regression analysis, and 95% prediction intervals were generated.

RESULTS

All three methods of estimating lung volumes from radiographs correlated well with total lung capacity from plethysmography (r = .89-.92). However, we found no statistically significant or clinically meaningful difference among the methods of estimating lung volume.

CONCLUSIONS

Lung volumes in children can be accurately estimated from specific measurements made on chest radiographs and on CT scans. Of the two methods tested with chest radiographs, the technique that required only two measurements from a posteroanterior chest radiograph was as accurate as the more complicated technique that required 21 measurements.

Lung transplantation in children and young adults with cardiovascular disease

Single or bilateral lung transplantation was performed in 20 patients with pulmonary hypertension or an inadequate pulmonary vascular bed; all but 1 had congenital heart disease. The average age was 6.3 years (range, 3 months to 23.9 years). All were in New York Heart Association class IV, and 6 were hospitalized and receiving intensive support before transplantation. Hospital survival was 70% (14/20), with three additional deaths at 7, 11, and 27 months. A prior thoracic operation contributed to three of six hospital deaths from hemorrhage. All late deaths were due directly or indirectly to obliterative bronchiolitis. At a mean follow-up of 19 months (range, 2 to 48 months), 10 of 11 survivors are in New York Heart Association class I. Survival after hospital discharge and incidence of obliterative bronchiolitis are similar in a contemporary group of 41 patients of comparable age who underwent lung transplantation for pulmonary disease (p = not significant). Single or bilateral lung transplantation is an acceptable therapy for children with pulmonary hypertension, congenital heart disease, or both. Further investigation in the areas of pretransplantation survival, operative risk factors, and long-term outcome of single-lung recipients and recipients with hemodynamically insignificant intracardiac lesions are needed to develop optimal decision-making strategies for these patients.

Use of aprotinin in pediatric lung transplantation

BACKGROUND

Aprotinin has been shown to decrease perioperative bleeding in adults undergoing cardiac surgery. We evaluated its efficacy in reducing blood loss in pediatric lung transplantation.

METHODS

Aprotinin was given to a group of pediatric lung transplant recipients (n = 24) identified as being at high risk for bleeding by virtue of preoperative diagnosis of cystic fibrosis or previous cardiothoracic operation (group 1). Comparison was made to a group of pediatric recipients (n = 19) believed to be at low risk for bleeding who did not receive aprotinin (group 2). All transplantations were accomplished with the use of cardiopulmonary bypass.

RESULTS

No difference in intraoperative blood requirement was identified between groups (18 +/- 3 cc/kg [group 1] versus 30 +/- 8 cc/kg [group 2], p = 0.16). Neither postoperative blood transfusion requirement (12 +/- 5 cc/kg [group 1] versus 16 +/- 6 cc/kg [group 2], p = 0.55) nor chest tube output in the first 24 postoperative hours (43 +/- 9 cc/kg [group 1] versus 53 +/- 13 cc/kg [group 2], p = 0.55) was significantly different between groups. Reexploration for bleeding was required in 8% (2 of 25) in group 1 and 16% (3 of 19) in group 2 (p = 0.64).

CONCLUSIONS

Aprotinin reduced the amount of perioperative hemorrhage in a group of pediatric patients at high risk for bleeding after lung transplantation. The magnitude of the effect could not be quantified but was sufficient to normalize the transfusion requirement to that of a low risk group of patients.

Isolated lung transplantation in children: pathological diagnosis and incidence of pulmonary complications

The pathological findings in the allografts of 14 children who underwent lung transplantation (LT) at St. Louis Children's Hospital, St. Louis, MO, in the period between July 1990 and May 1992 were reviewed. The study is based on histological analysis of 63 transbronchial biopsy (TBB) specimens, eight open lung biopsy specimens, and three pneumonectomy specimens. The mean age at transplantation was 10.5 years (range, 1 to 17 years) and the average follow-up period was 5.7 months. Sufficient tissue for an adequate pathological examination was obtained in 58 (92%) TBB specimens. Each specimen consisted of a mean of 6.12 tissue fragments, but only 4.79 fragments contained actual lung parenchyma for suitable examination. Ten patients (71%) had 23 biopsy-proven episodes of acute rejection with a frequency of 1.64 episodes per patient. The first episode was documented at a mean of 19 days after transplantation. Six patients (42.8%) developed bronchiolitis obliterans (BO). The definitive diagnosis of this condition was made either by open lung biopsy (n = 3) or on allograft pneumonectomy (n = 1), and it was infrequently recognized by TBB. Four of the six patients died less than 9 months after the diagnosis of BO was made, indicating the grave consequences of this complication. Two other deaths were attributed to the development of posttransplantation lymphoproliferative disorders.

Predictors of operative mortality and morbidity after infant heart transplantation

We retrospectively analyzed the impact of recipient, donor, and operative factors on the operative mortality and morbidity of 36 consecutive infant heart transplantations. Operative survival was excellent at 94%. Among 34 survivors, operative morbidity in 12 patients included acute severe allograft failure with or without prolonged ventilatory support. The cohort was characterized by age less than 4 months (32 of 36), a diagnosis of hypoplastic left heart syndrome (29 of 36), and the use of circulatory arrest (27 of 36); these variables were colinear and could not be used to predict operative mortality or morbidity. None of the remaining recipient, donor, or operative characteristics predicted survival or acute severe allograft failure. A donor-to-recipient weight ratio greater than 2 and a circulatory arrest time greater than 39 minutes predicted the need for prolonged ventilatory support. Despite the need for aggressive or prolonged support after 12 of 36 transplantations, operative survival was high at 94% (34 of 36 procedures, 32 of 34 patients). The use of less restrictive donor criteria combined with aggressive management of acute allograft failure can result in excellent operative survival after infant heart transplantation.

Predictors, frequency, and indications for cardiopulmonary bypass during lung transplantation in adults

The records for 162 lung transplantations performed in 158 patients were reviewed with regard to the predictors for, frequency of, and indications for using cardiopulmonary bypass during the procedure. There were a total of 8 en bloc double-lung transplantations, 83 single-lung transplantations, and 71 bilateral single-lung transplantations. Bypass was used electively for all double en bloc and three of the bilateral sequential lung transplantation procedures and for 26 unilateral lung replacement procedures in patients with pulmonary hypertension. Of the remaining patients, 1 single-lung transplant recipient required bypass for correction of a surgical mishap and 18 bilateral single-lung recipients required bypass during replacement of the second lung. No preoperative predictors for the need of bypass could be identified. Among the bilateral sequential lung recipients, the use of bypass did not seem to adversely affect outcome, as expressed in terms of the time until extubation, the time spent in the intensive care unit, and the time required to reach a room air oxygen tension greater than 60 mm Hg.

Biopsy-induced tricuspid regurgitation after cardiac transplantation

Transvenous endomyocardial biopsy is now well-established as the gold standard for evaluation of possible rejection episodes after cardiac transplantation. From 1985 to August 1992, 1990 patients have undergone 193 cardiac transplantations at Barnes Hospital. One hundred eighty-three patients survived their initial hospitalization and serve as the study group. Their records were reviewed for the purposes of identifying those with tricuspid regurgitation as a complication of right ventricular endomyocardial biopsy. These patients have undergone a total of 2,960 biopsies for an average of 16.2 biopsies per patient. Over a mean follow-up period of 4.22 years, all patients have been evaluated with standard two-dimensional echocardiograms. Mild to moderate tricuspid regurgitation was very common, but was thought to be biopsy-induced only if severe and accompanied by flail components of the tricuspid valve. Twelve patients were identified with this entity at our institution. Of these, 5 had no symptoms and were receiving no diuretics, 3 had mild symptoms consisting of lower extremity edema and continued to receive diuretics, 2 had moderate symptoms, and 2 had right heart failure and anasarca refractory to medical therapy. Both of the severely affected patients subsequently required tricuspid valve replacement. We conclude that the tricuspid valve apparatus is at significant risk of injury during endomyocardial biopsy, that most patients will be minimally symptomatic due to tricuspid regurgitation when this injury occurs, and that when the injury is accompanied by severe symptoms, the likelihood of improvement with medical therapy is small.

Pediatric lung transplantation. Indications, techniques, and early results

From July 1990 to April 1993, 36 lung transplantations in 33 patients were performed in our pediatric transplant program (0.25 to 23 years, mean age 10.3 years). Eight children had been continuously supported with a ventilator for 3 days to 4.5 years before transplantation and three were supported by extracorporeal membrane oxygenation. Indications for lung transplantation in this pediatric population included the following: cystic fibrosis (n = 13), pulmonary hypertension, and associated congenital heart disease (n = 10), pulmonary atresia, ventricular septal defect and nonconfluent pulmonary arteries (n = 3), pulmonary fibrosis (n = 6), and acute respiratory distress syndrome (n = 1). Three children underwent retransplantation for acute graft failure (n = 2) or chronic rejection (n = 1). Pulmonary fibrosis was related to complications of treatment of acute of myelogenous leukemia with bone marrow transplantation in two children and to bronchiolitis obliterans, bronchopulmonary dysplasia, interstitial pneumonitis, and Langerhans cell histiocytosis in four others. Thirteen children underwent lung transplantation and concomitant cardiac repair. Bilateral lung transplantation, ventricular septal defect closure and pulmonary homograft reconstruction of the right ventricular outflow tract to the transplanted lungs was performed in three children by means of a new technique that avoids the need for combined heart-lung transplantation. Two patients had ventricular septal defect closure and single lung transplant for Eisenmenger's syndrome, two had ligation of a patent ductus arteriosus and transplantation, three additional children underwent atrial septal defect closure and lung transplantation, and two underwent lung transplantation for congenital pulmonary vein stenosis. Eight early deaths and three late deaths occurred (actuarial 1-year survival 62%). Lung transplantation in children has been associated with acceptable early results, although modification of the adult implantation technique has been necessary. Lung transplantation and repair of complex congenital heart defects is possible; heart-lung transplantation may only be required for patients with severe left heart dysfunction and associated pulmonary vascular disease. Bronchiolitis obliterans remains a major concern for long-term graft function in pediatric lung transplant recipients.

Steroid withdrawal in the pediatric heart transplant recipient initially treated with triple immunosuppression

We prospectively evaluated the feasibility of withdrawing steroids 6 to 12 months after heart transplantation in 26 consecutive infants and children (median age at transplantation 6 weeks; range 5 days to 10.1 years) initially treated with triple immunosuppression (cyclosporine, azathioprine, and corticosteroids). Ongoing surveillance for cellular rejection was performed by endomyocardial biopsy in all patients and was performed electively in all subjects within 2 weeks after administration of steroids was discontinued. Significant rejection was defined as grade 2. Twenty-three of 26 patients were 6-month survivors and steroids were withdrawn in 21, with the other two survivors followed up elsewhere with triple immunosuppression. Seventeen (81%) of 21 patients were ultimately treated without maintenance steroids for a mean duration of 17 months (range 1 to 34 months), including 6 of 17 patients who had at least one episode of rejection within the first 6 months of transplantation. Five (24%) of 21 patients had rejection 2 weeks (n = 3) and 6 months (n = 2) after steroids were withdrawn, with one patient successfully withdrawn from steroids after a second attempt. In this latter group one patient underwent retransplantation because of severe coronary arteriopathy by angiography 10 months after transplantation and another died suddenly 18 months after transplantation despite resumption of steroids.(ABSTRACT TRUNCATED AT 250 WORDS)

Restrictive atrial septal communication as a determinant of outcome of cardiac transplantation for hypoplastic left heart syndrome

BACKGROUND

Infant cardiac transplantation for hypoplastic left heart syndrome (HLHS) can be performed with a high success rate, but it remains unclear whether variations in anatomy or degree of illness before transplantation can affect ultimate survival.

METHODS AND RESULTS

We analyzed the initial echocardiograms and pretransplant courses of 21 infants whose families chose transplantation as a primary therapy option for factors influencing survival. Sixteen of 21 were transplanted (mean wait, 18 days; range, 3 to 97 days) with 15 current (6- to 36-month) survivors, leading to a survival rate from presentation of 71% (70% confidence limit [CL], 61% to 81%) and an operative survival of 94% (70% CL, 81% to 99%). Seven of 20 listed for transplant (35%) had a severely restrictive interatrial communication, defined as a color flow jet width of 3 mm or less across the interatrial septum. Three of these 7 infants died at 4 (2) and 7 (1) weeks from congestive heart failure and progressive hypoxemia before transplantation. One died 2 months after transplant with an autopsy demonstrating pulmonary venous hypertensive disease, leading to a significantly higher relative risk for death (relative risk = 7.4, P = .01) for those infants with a severely restrictive interatrial communication versus those infants without severe restriction. The size and function of the right ventricle, left atrium, aorta, and tricuspid valve, as well as the magnitude of support on presentation, were not related to ultimate survival.

CONCLUSIONS

A severely restrictive interatrial communication is a frequent component of HLHS. When primary cardiac transplantation is the chosen therapy for HLHS, it is a significant negative risk factor for death primarily before transplantation.

Technique of transplantation for hypoplastic left heart syndrome with left superior vena cava

The presence of a left superior vena cava in infants with hypoplastic left heart syndrome complicates the technical performance of orthotopic cardiac transplantation. In this report we describe a modification of the recipient cardiectomy to maintain patency of the left superior vena cava, leaving the recipient coronary sinus as a conduit for it into the right atrium and avoiding complex venous reconstructions.

Damus-Kaye-Stansel with cavopulmonary connection for single ventricle and subaortic obstruction

Infants with single ventricle and transposition of the great arteries with or without aortic arch obstruction have a poor prognosis due in large part to the development of systemic outflow obstruction, a frequent consequence of pulmonary artery banding. Thus, the initial palliation and long-term treatment options are critical in terms of surgical choices and timing. We report our experience with 9 patients managed by neonatal pulmonary artery banding and early debanding, a Damus-Kaye-Stansel procedure, and either a modified Glenn shunt or a modified Fontan procedure. Some evidence of subaortic stenosis developed in every patient as manifested by a resting gradient across the systemic outflow tract (21.4 +/- 4.2 mm Hg), a small ventricular septal defect relative to the body surface area (1.57 +/- 0.39 cm2/m2), and a small ventricular septal defect relative to the aortic root cross-sectional area (0.70 +/- 0.04 cm2/m2). There were 1 early death and 1 late death after the Damus-Kaye-Stansel procedure. With the exception of 1 patient, the in-hospital course of the survivors was relatively uncomplicated. Two patients with levotransposition of the great arteries have required pacemakers. None of the survivors have residual systemic outflow obstruction. There is trivial or mild pulmonic insufficiency in 5 patients, which is not progressing. One patient had mild to moderate pulmonic insufficiency but died late presumably of an arrhythmia. We conclude that neonatal pulmonary artery banding coupled with planned early debanding, a Damus-Kaye-Stansel procedure, and cavopulmonary anastomosis is a relatively low-risk course for patients with this complex physiology.

Pediatric lung transplantation for pulmonary hypertension and congenital heart disease

Five children underwent lung transplantation for end-stage pulmonary hypertension and respiratory insufficiency associated with congenital heart disease. One (17 mo) had pulmonary hypertension with a patent ductus arteriosus and required two periods of preoperative extracorporeal membrane oxygenation before successful bilateral sequential lung transplantation. One (21 mo) required bilateral lung transplantation for pulmonary hypertension and bronchopulmonary dysplasia associated with iatrogenic injury to the left pulmonary artery. This child also had patent ductus arteriosus ligation and preoperative catheter closure of an atrial septal defect. Extracorporeal membrane oxygenation was required for early postoperative pulmonary support. One child underwent right single-lung transplantation and closure of an atrial septal defect for pulmonary hypertension. Two patients had single-lung transplantation for Eisenmenger's syndrome: 1 with muscular inlet ventricular septal defect closure, atrial septal defect closure, and right single-lung transplantation; 1 with ventricular septal defect closure, patent ductus arteriosus ligation, right ventricular outflow tract patch repair, and single-lung transplantation. All patients survived operation, with one late death (lymphoproliferative disease). The 4 survivors are all ambulatory without oxygen and have evidence of normal pulmonary artery pressure 9 to 12 months after transplantation.

Intraaortic balloon counterpulsation: patterns of usage and outcome in cardiac surgery patients

Between January 1, 1986, and May 6, 1991, 7,884 cardiac surgical procedures requiring cardiopulmonary bypass were performed at our institution, including 672 (9.8% of adult procedures) performed in 669 patients that were associated with preoperative (n = 240), intraoperative (n = 353), or postoperative (n = 79) use of an intraaortic balloon pump. The mean age of recipients was 65.3 years (range, 16 to 89 years). Intraaortic balloon pump usage increased during the study period from 6.4% of patients (83/1,298) in 1986 to 12.7% of patients (169/1,333) in 1990. The relative distribution between preoperative (mean, 35.7%), intraoperative (52.5%), and postoperative (11.8%) insertion remained nearly constant during the study period. The overall operative (30-day) mortality for patients with preoperative, intraoperative, or postoperative insertion of the intraaortic balloon pump was 19.6%, 32.3%, and 40.5%, respectively (X2 = 16.4; p less than 0.001). Although use of the intraaortic balloon pump in the intraoperative and postoperative settings is accompanied by a favorable outcome in most patients, the high associated mortality suggests the need for earlier use of the intraaortic balloon pump or other supportive measures such as the ventricular assist device.

Response of the hypertrophied left ventricle to global ischemia. Comparison of hyperkalemic cardioplegic solution with and without verapamil

The hypertrophied left ventricle is at considerably greater risk for injury when subjected to global ischemia than is an otherwise normal heart. We evaluated the efficacy of verapamil, a calcium-channel blocking agent, as an adjunct to standard crystalloid cardioplegic solution in animals with left ventricular hypertrophy subjected to myocardial ischemia during cardiopulmonary bypass. Infracoronary aortic stenosis was produced in 15 mongrel puppies by plication of the noncoronary cusp of the aortic valve. Studies were conducted 3 to 4 months later. Left ventricular catheter-tip pressure transducers and major and minor axis ultrasonic dimension crystals were inserted, and the animals were then supported by cardiopulmonary bypass with 30 minutes of normothermic ischemia. Animals were randomized to receive either standard hyperkalemic crystalloid cardioplegic solution (n = 8) or the same solution with verapamil, 0.1 mg/kg (n = 7). After the 30 minutes of ischemia, the animals were supported on cardiopulmonary bypass for an additional 30 minutes and then separated from bypass. They were then studied for another 2 hours by measurement of myocardial adenosine triphosphate content, myocardial blood flow, systolic function with use of the end-systolic pressure/volume ratio, and compliance with use of the natural strain coefficient of the minor axis at 15 mm Hg end-diastolic pressure. There was a better recovery of systolic function in the animals treated with verapamil (89.2% versus 63.3%). The compliance as measured with use of the minor axis natural strain coefficient returned essentially to baseline in the group of animals treated with verapamil (0.236 +/- 0.038 before ischemia and 0.254 +/- 0.043 2 hours after ischemia), but it fell markedly in the control animals (0.219 +/- 0.027 before ischemia and 0.153 +/- 0.016 2 hours after ischemia). Myocardial adenosine triphosphate levels were not significantly different at any time during the study. Likewise, myocardial blood flow was not significantly different between groups. We conclude that the addition of verapamil to hyperkalemic cardioplegic solution improves recovery of both systolic and diastolic function after global ischemia in dogs with left ventricular hypertrophy resulting from aortic stenosis. The precise mechanism for this is unknown.

Is total pelvic exenteration reasonable primary treatment for rectal carcinoma?

Total pelvic exeneration (TPE) is reasonable primary surgical therapy in select patients with large bulky locally invasive rectal cancers that can be removed en bloc. Many do not have either nodal or distant metastasis. Furthermore, TPE can be curative and often is palliative for similar lesions that are recurrent or nonresponsive to radiation therapy. Operative mortality rates should be under 10% and can be under 5% for primary cases. Although improvement in preoperative management and operative technique, especially with urinary conduits and postoperative care is clear, both early and late complications are significant. Unfortunately, preoperative identification of those patients requiring TPE rather than abdominoperineal or low anterior resection remains poor. Furthermore, recent improvements in techniques for pelvic slings to prevent small bowel entrapment and protection from irradiation or myocutaneous flaps to obliterate the massive dead space are not yet clearly established as preventors of either early or later complications.

Internal mammary artery grafts: technical factors influencing patency

Eight hundred fourteen patients with internal mammary artery (IMA) coronary artery bypass grafts have been restudied 961 times with coronary arteriography, primarily to evaluate the patency of the grafts in the setting of symptomatic coronary occlusive disease. Their records were reviewed to assess graft patency as related to the technical aspects of coronary artery bypass surgery. Patency was evaluated using life-table analysis of the data. The method of harvesting the IMA played no role in patency. The left anterior descending coronary artery was the recipient coronary artery with the highest patency rate. The left IMA had a significantly higher patency rate than the right IMA. As a group, the IMAs had a significantly higher patency rate than saphenous vein grafts. However, there was no difference between right IMA grafts and saphenous vein grafts. The mammary artery grafts that remained patent throughout the study had a significantly higher blood flow after bypass than did those that became occluded (43.0 +/- 0.9 versus 28.9 +/- 1.8 ml/min; p less than .001).

Pathophysiology of chronic cyanosis in a canine model. Functional and metabolic response to global ischemia

To investigate the pathophysiology of chronic cyanosis, we subjected 14 adult mongrel dogs to diversion of the inferior vena cava to the right inferior pulmonary vein. This produced a mean oxygen tension of 42 +/- 2 mm Hg and a calculated right-to-left shunt of 52.0% +/- 3.9%. These animals (Group C) and 15 normal dogs (Group N) were subjected to cardiopulmonary bypass with 20 minutes of normothermic global ischemia. Functional indices studied were rate of rise of left ventricular pressure and the end-systolic pressure/volume ratio. Metabolic status was assessed by obtaining transmural myocardial biopsy specimens for measurement of adenosine triphosphate content. Myocardial blood flow was measured with radiolabeled microspheres. There were no significant differences between Group C and Group N in either functional index or blood flow measurement prior to global ischemia. At 45 minutes after ischemia, Group N animals had a significantly greater rate of rise of left ventricular pressure (at a left ventricular end-diastolic pressure of 0, 5, 10, and 15 mm Hg, p less than 0.025 to 0.05) and subendocarial perfusion (endocardial/epicardial flow ratio 0.961 +/- 0.037 versus 0.815 +/- 0.021, p less than 0.01). At 90 minutes after ischemia, Group N animals exhibited a significantly higher end-systolic pressure/volume ratio (4.9 +/- 0.7 versus 3.0 +/- 0.4 mm Hg/ml, p less than 0.05), rate of rise of left ventricular pressure (at an end-diastolic pressure of 0 to 20 mm Hg, p less than 0.005 to 0.05), and endocardial/epicardial flow ratio (1.065 +/- 0.046 versus 0.829 +/- 0.059, p less than 0.01). No differences in adenosine triphosphate content were found at any sampling period. The Group C left ventricles exhibited no hypertrophy but were significantly dilated compared to Group N (38.8 +/- 0.3 versus 30.1 +/- 0.2 mm, p less than 0.05). Inferior vena cava to pulmonary vein diversion produces cyanosis with left ventricular dilatation but without hypertrophy. It is proposed that abnormal loading characteristics of the left ventricle are responsible for the functional derangements that result from global ischemia.