Interaction of Mycobacterium avium complex with human respiratory epithelial cells

Adherence of Mycobacterium avium complex (MAC) to human respiratory epithelial cells (HEp-2) induced 2 distinct modes of internalization. In the first, MAC induced ruffling of HEp-2 cell membrane and formation of surface projections securing the bacilli on the surface, and concurrent membrane depressions, beneath the sites of attachment of bacilli, resulted in internalization of the organisms. The second mode involved formation of membrane folds wrapping around the bacilli, followed by internalization. Two MAC proteins of approximately 31 kD and approximately 25 kD, respectively, were identified that mediated these interactions specific for HEp-2 cells. The N-terminal amino acid sequence of the 31-kD MAC protein displayed homology with the 21-kD hypothetical protein of Mycobacterium tuberculosis, and the 25-kD MAC protein showed homology with Mn-superoxide dismutase of MAC and Mycobacterium leprae. These 2 HEp-2 cell-specific MAC proteins may be involved in the interaction of MAC with epithelial cells.

Surgical intervention for complications of transcatheter dilation procedures in congenital heart disease

BACKGROUND

Transcatheter interventions have assumed an important role in the management of many forms of congenital heart disease. While complications of transcatheter interventions are uncommon and usually minor, significant complications requiring operation do occur on occasion. The purpose of this report is to present our experiences with seven such complications, and to review the literature on this topic.

METHODS

Seven patients who required operation after a transcatheter dilation procedure between 1992 and 1998 are described. Three patients required retrieval of retained foreign bodies (stents or balloons), and repair of the underlying abnormality. Two patients underwent repair of fistulas between 2 great vessels, or a great vessel and a cardiac chamber. One patient required operation for a postdilation aneurysm. One patient underwent urgent repair of severe aortic regurgitation after balloon aortic valvuloplasty.

RESULTS

All patients survived and are doing well, with no further need for catheter or operative intervention, from 8 months to 6 years after operation. Additional reported complications requiring operation are discussed as well.

CONCLUSIONS

Operation for complications of catheter interventions in congenital heart disease is seldom necessary. Though uncommon, a variety of such complications may occur, including vascular, valvar, intracardiac, and foreign body complications. When operation is required, results are typically very good.

Revision of previous Fontan connections to total extracardiac cavopulmonary anastomosis: A multicenter experience

BACKGROUND

Conversion to total extracardiac cavopulmonary anastomosis is an option for managing patients with dysfunction of a prior Fontan connection.

METHODS

Thirty-one patients (19.9 +/- 8.8 years) underwent revision of a previous Fontan connection to total extracardiac cavopulmonary anastomosis at four institutions. Complications of the previous Fontan connection included atrial tachyarrhythmias (n = 20), progressive heart failure (n = 17), Fontan pathway obstruction (n = 10), effusions (n = 10), pulmonary venous obstruction by an enlarged right atrium (n = 6), protein-losing enteropathy (n = 3), right atrial thrombus (n = 2), subaortic stenosis (n = 1), atrioventricular valve regurgitation (n = 3), and Fontan baffle leak (n = 5). Conversion to an extracardiac cavopulmonary connection was performed with a nonvalved conduit from the inferior vena cava to the right pulmonary artery, with additional procedures as necessary.

RESULTS

There have been 3 deaths. Two patients died in the perioperative period of heart failure and massive effusions. The third patient died suddenly 8 months after the operation. All surviving patients were in New York Heart Association class I (n = 20) or II (n = 7), except for 1 patient who underwent heart transplantation. Early postoperative arrhythmias occurred in 10 patients: 4 required pacemakers, and medical therapy was sufficient in 6. In 15 patients, pre-revision arrhythmias were improved. Effusions resolved in all but 1 of the patients in whom they were present before revision. The condition of 2 patients with protein-losing enteropathy improved within 30 days.

CONCLUSIONS

Conversion of a failing Fontan connection to extracardiac cavopulmonary connection can be achieved with low morbidity and mortality. Optimally, revision should be undertaken early in symptomatic patients before irreversible ventricular failure ensues.

A 5-year experience with surgical repair of atrial septal defect employing limited exposure

BACKGROUND

There has been a trend in recent years towards less invasive therapy for many congenital cardiac malformations. For the past 5 years, we have employed a technique of limited surgical exposure when repairing atrial defects within the oval fossa.

METHODS

Over the 5-year period from July 1992 to August 1997, 115 consecutive patients underwent surgical repair of an isolated atrial septal defect in the region of the oval fossa by a single surgeon. The patients had a limited midline skin incision starting at the line of the nipples and extending inferiorly across 2 to 3 intercostal spaces. A partial sternotomy was performed, sparing the manubrium. Standard instruments and cannulation techniques were used for cardiopulmonary bypass and fibrillatory arrest.

RESULTS

There were no deaths and no major complications. The median time to extubation after leaving the operating room was 3 hours (30 minutes to 8 days). Mediastinal drains were removed the morning after surgery. The median stay in the intensive care unit was 7 hours (3 hours to 10 days), and patients were discharged from the hospital a median of 4 days postoperatively (2 to 23 days).

CONCLUSIONS

This approach using limited exposure can be applied safely without any new instruments and without peripheral incisions or sites of vascular access, while providing a comfortable exposure for the surgeon and achieving a cosmetically superior result for the patient.

Is it necessary to routinely fenestrate an extracardiac fontan?

OBJECTIVES

This study was conducted to assess the need for, and use of, fenestration of an extracardiac conduit Fontan.

BACKGROUND

Fenestration of a Fontan connection has been proposed as a means of improving outcomes of single ventricle palliation. The benefit of fenestration is likely to be greatest in the early postoperative period when patients may experience increased pulmonary vascular resistance and decreased ventricular function due to the effects of cardiopulmonary bypass, aortic cross-clamping and positive pressure ventilation. However, there are potential drawbacks to fenestration. The utility of fenestration with extracardiac Fontan operation has not been determined.

METHODS

Since 1992, 81 patients have undergone a modification of the Fontan procedure in which an extracardiac inferior cavopulmonary conduit is used in combination with a previously staged bidirectional Glenn anastomosis. We conducted a retrospective review of these patients.

RESULTS

Fenestration was performed selectively in 32 patients (39%), including only 2 of the last 38 (5%). In seven patients, a fenestration was placed or clipped in the early postoperative period without cardiopulmonary bypass. There were two operative deaths. Prolonged (>2 weeks) pleural drainage occurred in 13 patients, 8 with fenestration and 5 without. In addition to undergoing earlier Fontan in our experience, patients who had a fenestration placed had significantly higher preoperative pulmonary vascular resistance, significantly higher common atrial pressure after Fontan and significantly lower post-Fontan systemic arterial oxygen saturation. Fontan pressure did not differ between nonfenestrated and fenestrated patients. At follow-up ranging to five years, there were two late deaths and no patients developed protein losing enteropathy.

CONCLUSIONS

Fenestration is not necessary in most Fontan patients when an extracardiac conduit technique is performed as described in this article, and therefore, should not be performed routinely with the extracardiac conduit Fontan. The need for fenestration should be assessed after cardiopulmonary bypass when hemodynamics can be evaluated accurately. Fenestration can be placed and revised easily without bypass and with minimal intervention in patients with an extracardiac conduit Fontan.

Antimycobacterial activities of riminophenazines

Riminophenazines were specifically developed as drugs active against Mycobacterium tuberculosis but extensive research over several decades has shown that these compounds are also active against many other mycobacterial infections, particularly those caused by Mycobacterium leprae and the Mycobacterium avium complex (MAC). Clofazimine, the lead compound in this series, is included in the regimens that are approved by the WHO for the treatment of leprosy and has contributed significantly to the control of that disease, particularly that caused by dapsone-resistant bacteria. Despite early problems, clofazimine has shown clinical efficacy in tuberculosis, in particular that caused by multiple drug resistant strains. Clofazimine does not induce resistance and also inhibits emergence of resistance to isoniazid in M. tuberculosis. The efficacy of clofazimine against MAC is more varied and the availability of better drugs has limited its use. Newer riminophenazines, such as B746 and B4157, not only showed increased anti-mycobacterial activity but also produced less skin pigmentation, which is the main drawback of this group of compounds. The most important virtues of riminophenazines, such as intracellular accumulation in mononuclear phagocytic cells, anti-inflammatory activity, a low incidence of drug resistance and slow metabolic elimination, make them attractive candidates for the treatment of mycobacterial infections. It is essential, however, to investigate the newer analogues clinically, while continuing the pursuit of alternate candidates that demonstrate higher anti-mycobacterial activity and lower rates of skin pigmentation.

Resection of subaortic stenosis; can a more aggressive approach be justified?

OBJECTIVES

Discrete subaortic stenosis causes left ventricular outflow tract (LVOT) obstruction and often produces aortic regurgitation (AR) which alone may precipitate surgical intervention. Conventional resection relieves the obstruction, but the recurrence rate is high, and the AR is little changed as the thick fibrous membrane which extends onto the valve leaflets remains. We studied whether an aggressive surgical approach could reduce both the severity of AR and rate of recurrence of obstruction associated with discrete subaortic stenosis, and whether this aggressive approach could be justified.

METHODS

Between June 1992 and April 1996, 37 patients aged 0.5-35 years (median 7.5) underwent resection of a discrete subaortic membrane. Ten underwent re-operation for recurrent obstruction and eight followed previous ventricular septal defect closure. LVOT gradient was measured using the modified Bernoulli equation and AR was graded on a scale of 0-4 (0 = none, 4 = severe). Postoperative assessment was performed early (<7 days) and at mid-term (27.0 months; range 2-59 months).

RESULTS

There was significant improvement in AR from mild/moderate to none/trivial (P = 0.019) immediately postoperatively and LVOT gradient from 66.9+/-30.4 to 15.1+/-12.2 mmHg (P < 0.0001). By stepwise logistic regression preoperative gradient correlated significantly with postoperative mild/moderate AR (P = 0.015) and LVOT gradient (P = 0.0036). Preoperative mild/moderate AR also correlated with postoperative mild/moderate AR (P = 0.034). Five patients developed complete heart block, four undergoing reoperation for recurrent obstruction, and one preoperatively had right bundle branch block from previous ventricular septal defect repair. At mid-term follow-up there was no increase in AR or LVOT gradient (14.8+/-12.8 mmHg). Early post-operative AR was the strongest predictor of late mild/moderate AR (P = 0.02). Early post-operative gradient was a weaker predictor (P = 0.04). Pre-operative and early post-operative gradient were significant predictors of late gradient (P = 0.0038; <0.0001, respectively). No patient required reoperation for recurrent obstruction; one underwent late aortic valve replacement for severe AR.

CONCLUSIONS

An aggressive surgical approach to discrete subaortic stenosis produces excellent relief of obstruction and frees the valve leaflets, significantly reducing associated AR at early and mid-term follow-up with low morbidity for primary operation. Long-term follow-up is required to confirm whether this early benefit is maintained.

Early results of the extracardiac conduit Fontan operation

BACKGROUND

Among the modifications of the Fontan operation, the extracardiac approach may offer the greatest potential for optimizing early postoperative ventricular and pulmonary vascular function, insofar as it can be performed with short periods of normothermic partial cardiopulmonary bypass and without cardioplegic arrest in most cases. In this study, we reviewed our experience with the extracardiac conduit Fontan operation, with a focus on early postoperative outcomes.

METHODS AND RESULTS

Between July 1992 and April 1997, 51 patients (median age 4.9 years) underwent an extracardiac conduit Fontan operation. Median cardiopulmonary bypass time was 92 minutes and has decreased significantly over the course of our experience. Intracardiac procedures were performed in only 5 patients (10%), and the aorta was crossclamped in only 11 (22%). Intraoperative fenestration was performed in 24 patients (47%). There were no early deaths. Fontan failure occurred in 1 patient who was a poor candidate for the Fontan procedure. Transient supraventricular tachyarrhythmias occurred in 5 patients (10%). Median duration of chest tube drainage was 8 days. Factors significantly associated with prolonged resource use (mechanical ventilation, inotropic support, intensive care unit stay, and hospital stay) included longer bypass time and higher Fontan pressure. At a median follow-up of 1.9 years, there was 1 death from bleeding at reoperation.

CONCLUSIONS

The extracardiac conduit Fontan procedure can be performed with minimal mortality and morbidity. Improved results may be related to advantages of the extracardiac approach and improved preservation of ventricular and pulmonary vascular function.

Compression of the central airways by a dilated aorta in infants and children with congenital heart disease

BACKGROUND

Children with congenital heart disease often experience respiratory symptoms in the preoperative and perioperative periods, which can complicate their management. An uncommon but important cause of respiratory insufficiency in such children is external airway compression.

METHODS

We operated on 5 patients (median age, 6 months) with significant respiratory distress attributable to compression of the central airways by a dilated ascending aorta before or after repair of concomitant cardiovascular defects. Four of these patients had right aortic arch and 3 had pulmonary atresia with a ventricular septal defect and major aortopulmonary collaterals. In all patients, aortopexy was performed at the time of operation for the cardiovascular defects (n = 3) or after symptoms developed in the postoperative period (n = 2). The 3 patients in whom airway compression produced symptoms preoperatively also underwent reduction ascending aortoplasty.

RESULTS

Symptoms resolved immediately after operation in 3 patients, whereas symptoms persisted in the other 2 patients and tracheostomy was required. At follow-up of 20 months to 5 years, all patients are alive and well, with mild or moderate respiratory symptoms in the 2 patients who required tracheostomy, both of whom were decannulated within 13 months.

CONCLUSIONS

External airway compression can cause significant morbidity in patients with congenital heart defects other than vascular rings. In patients with respiratory symptoms in the context of a lesion that involves increased aortic outflow during intrauterine life and consequently, an enlarged ascending aorta, such as tetralogy of Fallot with pulmonary atresia, airway compression should be considered as a cause, especially if a right aortic arch is present or the patient also has pulmonary atresia with a ventricular septal defect and collaterals. Attempts to address this problem surgically may provide substantial relief, but increasing duration of airway compression is likely to lead to tracheal or bronchial malacia and persistent symptoms even after the compression is relieved.

Role of the endothelium in placental dysfunction after fetal cardiac bypass

BACKGROUND

Fetal cardiac bypass causes placental dysfunction, characterized by increased placental vascular resistance, decreased placental blood flow, hypoxia, and acidosis. Vasoactive factors produced by the vascular endothelium, such as nitric oxide and endothelin 1, are important regulators of placental vascular tone and may contribute to this placental dysfunction.

METHODS

To investigate the role of the vascular endothelium in placental dysfunction related to fetal cardiac bypass, we studied 3 groups of fetal sheep. In the first group (n = 7) we determined placental hemodynamic responses before and after bypass to an endothelium-dependent vasodilator (acetylcholine), an endothelium-independent vasodilator (nitroprusside), and endothelin 1. In the second group (n = 8) a nonspecific endothelin receptor blocker (PD 145065) was administered and placental hemodynamic values were measured before and after bypass. In the third group (n = 5) endothelin 1 levels were measured before and after bypass.

RESULTS

Before fetal cardiac bypass exogenous endothelin 1 decreased placental blood flow by 9% and increased placental resistance by 9%. After bypass endothelin 1 decreased placental flow by 47% and increased resistance by 106%. There was also a significant attenuation of the placental vascular relaxation response to acetylcholine after bypass, whereas the response to nitroprusside was not significantly altered. In fetuses that received the PD 145065, placental vascular resistance increased significantly less than in control fetuses (28% versus 62%). Similarly, placental blood flow decreased significantly more (from 6. 3 +/- 3.1 to 28.3 +/- 10.4 pg/mL; P =.01) in control fetuses than in fetuses receiving PD 145065 (33% versus 20%). Umbilical venous endothelin 1 levels increased significantly in fetuses exposed to fetal bypass but did not change in control fetuses.

CONCLUSIONS

The basal endothelial regulatory mechanisms of placental vascular tone were deranged after fetal cardiac bypass. Endothelin receptor blockade, which substantially reduced postbypass placental dysfunction, and other interventions aimed at preserving endothelial function may be effective means of optimizing fetal outcome after cardiac bypass.

Results of 102 cases of complete repair of congenital heart defects in patients weighing 700 to 2500 grams

BACKGROUND

Published data suggest that low birth weight is a risk factor for poor outcome in corrective surgery for many cardiac defects. Congenital heart defects in low birth weight infants are typically managed with supportive therapy or palliative operations, with definitive repair delayed. The morbidity associated with such approaches is high.

METHODS

Since 1990 complete repair of congenital heart defects (other than patent ductus arteriosus) has been performed in 102 infants no larger than 2500 g (median 2100 g, range 700-2500 g), including 16 no larger than 1500 g. Defects included ventricular septal defect (n = 22), tetralogy of Fallot complexes (n = 20), transposition complexes (n = 13), aortic coarctation (n = 12), interrupted arch (n = 10), truncus arteriosus (n = 8), atrioventricular septal defect (n = 6), total anomalous pulmonary venous return (n = 5), and other (n = 6).

RESULTS

Preoperative morbidity was more common among patients referred late for surgical correction. There were 10 early deaths (10%) attributable to cardiac failure (n = 4), arrhythmia (n = 1), multiorgan failure (n = 1), sepsis (n = 1), idiopathic coronary artery intimal necrosis (n = 1), foot gangrene (n = 1), and pulmonary hemorrhage (n = 1). No patient had postbypass intracerebral hemorrhage. At follow-up (median 36 months) there were 8 late deaths, and 8 patients underwent 10 reinterventions. There was no evidence of neurologic sequelae attributable to the operation.

CONCLUSIONS

In general, delaying repair of congenital heart defects in low birth weight infants does not confer a benefit and is associated with higher preoperative morbidity. Complete repair of both simple and complex lesions can be achieved in such cases with good results. Growth after repair approximates the normal curve for low birth weight infants without heart disease. It is recommended that such infants, especially when they have symptoms, undergo early surgical repair rather than prolonged medical management or other forms of palliation.

Endothelin receptor blockade prevents the rise in pulmonary vascular resistance after cardiopulmonary bypass in lambs with increased pulmonary blood flow

BACKGROUND

Children with increased pulmonary blood flow may experience morbidity as the result of increased pulmonary vascular resistance after operations in which cardiopulmonary bypass is used. Plasma levels of endothelin-1, a potent vasoactive substance implicated in pulmonary hypertension, are increased after cardiopulmonary bypass.

OBJECTIVES

In a lamb model of increased pulmonary blood flow after in utero placement of an aortopulmonary shunt, we characterized the changes in pulmonary vascular resistance induced by hypothermic cardiopulmonary bypass and investigated the role of endothelin-1 and endothelin-A receptor activation in postbypass pulmonary hypertension.

METHODS

In eleven 1-month-old lambs, the shunt was closed, and vascular pressures and blood flows were monitored. An infusion of a selective endothelin-A receptor blocker (PD 156707; 1.0 mg/kg/h) or drug vehicle (saline solution) was then begun 30 minutes before cardiopulmonary bypass and continued for 4 hours after bypass. The hemodynamic variables were monitored, and plasma endothelin-1 concentrations were determined before, during, and for 6 hours after cardiopulmonary bypass.

RESULTS

After 90 minutes of hypothermic cardiopulmonary bypass, both pulmonary arterial pressure and pulmonary vascular resistance increased significantly in saline-treated lambs during the 6-hour study period (P <.05). In lambs pretreated with PD 156707, pulmonary arterial pressure and pulmonary vascular resistance decreased (P <. 05). After bypass, plasma endothelin-1 concentrations increased in all lambs; there was a positive correlation between postbypass pulmonary vascular resistance and plasma endothelin-1 concentrations (P <.05).

CONCLUSIONS

This study suggests that endothelin-A receptor-induced pulmonary vasoconstriction mediates, in part, the rise in pulmonary vascular resistance after cardiopulmonary bypass. Endothelin-A receptor antagonists may decrease morbidity in children at risk for postbypass pulmonary hypertension. This potential therapy warrants further investigation.

Echocardiographic diagnosis alone for the complete repair of major congenital heart defects

OBJECTIVES

The study was done to determine the diagnostic accuracy of echocardiography alone in the preoperative diagnosis of children with major congenital heart defects undergoing primary complete repair.

BACKGROUND

Although echocardiography is well established as the first-line imaging technique for the diagnosis of all forms of congenital heart disease, most institutions continue to perform cardiac catheterization prior to complete repair of more complex defects.

METHODS

To determine the diagnostic accuracy of echocardiography alone and echocardiography plus catheterization, we reviewed the records of 503 children with major congenital heart defects who underwent primary complete repair at our institution between July 1992 and June 1997. We included children with transposition of the great arteries, tetralogy of Fallot, double-chamber right ventricle, interrupted aortic arch, aortic coarctation, atrioventricular septal defect, truncus arteriosus, aortopulmonary septal defect, and totally anomalous pulmonary venous return. We excluded children with less complex defects such as isolated shunt lesions, as well as those with the most complex defects that would require surgical palliation (e.g., functional univentricular heart). We defined major errors as those that increased the surgical risk and minor errors as those that did not. Errors in diagnosis were determined at surgery.

RESULTS

Eighty-two percent of children (412 of 503) underwent surgery after preoperative diagnosis by echocardiography alone. There were 9 major (2%) and 10 minor errors in the echocardiography alone group and 7 major and 5 minor errors in the echocardiography plus catheterization group. The most common type of error was misidentification of coronary artery anatomy in patients with transposition of the great arteries. No error in either group resulted in surgical morbidity or mortality.

CONCLUSIONS

This study suggests that echocardiography alone is an accurate tool for the preoperative diagnosis of major congenital heart defects in most children undergoing primary complete repair, and may obviate the need for routine diagnostic catheterization.

Multiple ventricular septal defects: how and when should they be repaired?

BACKGROUND

Congenital heart lesions with multiple ventricular septal defects remain a surgical challenge. Traditional approaches often rely on either ventriculotomy for exposure or palliation with pulmonary artery banding. However, indications for repair versus palliation and for various approaches to surgical exposure are not clearly defined.

METHODS

From July 1992 to January 1998, 45 patients with multiple (>/=2) ventricular septal defects (37 with associated lesions) underwent surgery. Median age was 86 days; all but 4 patients were infants. The mean number of defects was 3.7, and almost half of the patients had more than 3 defects. Apical muscular defects were present in 62% of patients. Thirty-one patients underwent primary complete repair through a right atriotomy or trans-semilunar valve approach (group 1), 8 had palliation (group 2), and 6 underwent complete repair after prior palliation elsewhere (group 3). No patient had a ventriculotomy.

RESULTS

One early death occurred in a group 1 patient. Four patients who had had palliation (50%) underwent early reoperation for pulmonary artery band revision because of failure to thrive or band removal after spontaneous closure of the defects. At follow-up (median 22 months), there was 1 death in a group 2 patient (palliation) and 1 other group 2 patient required cardiac transplantation. The only late reoperation was for removal of the pulmonary artery band and closure of multiple apical defects in a group 2 (palliation) patient. No patients who underwent repair have hemodynamically significant residual defects.

CONCLUSIONS

In our experience, palliation of multiple ventricular septal defects is associated with greater morbidity than primary repair. Multiple defects can almost always be repaired adequately in early infancy without ventriculotomy, although "Swiss-cheese" septum may be an indication for palliation.

Accessory and anomalous atrioventricular valvar tissue causing outflow tract obstruction: surgical implications of a heterogeneous and complex problem

OBJECTIVES

The purpose of this study was to determine the effect of accessory or anomalous atrioventricular valvar apparatus on relief of outflow tract obstruction.

BACKGROUND

Outflow tract obstruction due to accessory tissue or anomalous attachments of the atrioventricular valvar apparatus is an unusual but well-recognized problem. In addition to obstruction, anomalous attachments of the atrioventricular valvar apparatus may interfere with procedures to relieve outflow tract obstruction or perform outflow tract reconstruction.

METHODS

Since 1992, we have operated on 21 patients (median age 4 years) with systemic (n=13), pulmonary (n=5) or bilateral (n=3) outflow tract obstruction due to accessory atrioventricular valvar tissue and/or anomalous attachments of the subvalvar apparatus. Primary diagnoses were isolated obstruction of the systemic outflow tract or aortic arch (n=7), transposition complexes (n=6), previously repaired atrioventricular septal defect (n=3), functionally single ventricle (n=3) and ventricular septal defect with pulmonary outflow obstruction (n=2). Outflow tract gradients ranged from 20-110 mm Hg (median 58 mm Hg).

RESULTS

Complete relief of obstruction due to atrioventricular valvar anomalies was possible in 14 patients. In six patients, the planned procedure either had to be modified or only partial relief of the obstruction was achieved. In the remaining patient, who had borderline functionally single ventricle heart disease (unbalanced atrioventricular septal defect) and systemic outflow obstruction due to accessory and functional valvar apparatus, support was withdrawn because the parents refused univentricular palliation and the valvar anomalies precluded a Ross-Konno procedure. There were two early deaths. At follow-up ranging from 1 to 66 months (median 27 months), there was one death, and there has been no recurrence of outflow tract obstruction or residual atrioventricular valvar tissue.

CONCLUSIONS

Outflow tract obstruction caused by accessory or anomalous atrioventricular valvar structures is an uncommon and heterogeneous group of conditions that can have significant surgical implications. In the majority of cases, tailoring of surgical techniques will permit complete relief of obstruction. However, such anomalies may limit standard surgical options and necessitate an innovative approach in some patients.

Alternative approach to the repair of Ebstein's malformation: intracardiac repair with ventricular unloading

BACKGROUND

Moderate to severe Ebstein's malformation remains a surgical challenge. Although the various approaches that have been used are appropriate and successful in many patients, there are many for which these approaches are suboptimal. To improve the prognosis for patients across the full spectrum of Ebstein's malformation, alternative surgical approaches are necessary.

METHODS

From December 1995 to October 1997, 10 patients (median age, 9 years) with moderate or severe Ebstein's malformation and mild to severe tricuspid regurgitation had partial biventricular repair with reduction of right ventricular volume load. All patients were symptomatic in New York Heart Association functional class II (n = 9) or III (n = 1). In addition to bidirectional cavopulmonary anastomosis and closure of intracardiac defects in all patients, 6 underwent tricuspid valve repair using a variety of procedures, most often simple horizontal annuloplasty.

RESULTS

There were no deaths. Early reoperation was required in 1 patient (atrial septostomy on the day after operation for right ventricular failure) and another required revision of the tricuspid valve repair 10 months postoperatively for recurrent regurgitation. At follow-up ranging from 2 to 24 months, all patients are in New York Heart Association class I and have trivial tricuspid regurgitation, including the 4 who had no tricuspid valvuloplasty performed.

CONCLUSIONS

We have presented an alternative approach to the management of severe Ebstein's malformation that focuses on both the tricuspid valve and the right ventricle. Just as tricuspid valve repair and reduction of regurgitation will likely improve right ventricular performance, reducing the volume load on the ventricle may improve both ventricular (right and left) and tricuspid valve function. All patients have demonstrated improved exercise tolerance and right heart function at follow-up ranging to 24 months. Additional experience will be necessary to evaluate this strategy more completely.

Extracardiac conduit Fontan procedure without cardiopulmonary bypass

There are a number of potential advantages of extracardiac conduit cavopulmonary anastomosis for palliation of functional single ventricle heart disease, including the ability to perform the operation with no aortic cross-clamping and with minimal duration of extracorporeal circulation. In many patients, it may be possible to perform the procedure without cardiopulmonary bypass altogether. In this report, we present our technique for performing the extracardiac conduit Fontan operation without cardiopulmonary bypass.

Repair of secundum atrial septal defect: limiting the incision without sacrificing exposure

A simple and effective technique for repair of secundum atrial septal defect is described. The heart is exposed through a limited midline skin incision and partial sternotomy, and the atrial septal defect is closed through a right atriotomy with ascending aortic and dual venous cannulation. This approach achieves a cosmetically superior result with standard instrumentation and cardiopulmonary bypass techniques, without compromising exposure or using peripheral incisions.

Atrioventricular septal defect with common valvar orifice and tetralogy of Fallot revisited: making a case for primary repair in infancy

Atrioventricular septal defect with common valvar orifice and tetralogy of Fallot is a rare combination of congenital cardiac anomalies. Approaches to this lesion have tended to emphasize either staged repair or complete repair beyond infancy. Between July 1992 and August 1997, nine patients underwent repair of complete atrioventricular septal defect with tetralogy of Fallot. One patient, aged 9.6 years at the time of repair, had previously undergone construction of a modified Blalock-Taussig shunt. Primary complete repair was performed in the other 8 patients at ages ranging from 2.5 to 16 months (median 4.6 months), and all but one were infants. All patients had a Rastelli type C defect, a single ventricular septal defect with inlet and outlet components, and malalignment of the muscular outlet septum with subpulmonary stenosis. A single patch technique, with closure of the zone of apposition ('cleft') in the left atrioventricular valve, was used in all eight patients undergoing primary repair, while a double patch was employed in the previously palliated older patient. In all cases of repair using a single patch, the anterosuperior bridging leaflet was divided obliquely to the right, following the malaligned outlet septum, in order to avoid subaortic obstruction. Repair of the right ventricular outflow tract included infundibular myectomy in eight, pulmonary valvotomy in four, infundibular or transannular patching in three and one, respectively, and reconstruction with a valved allograft conduit in two patients. There was no early mortality or significant morbidity. At a median follow-up of 45 months, there had been one death related to non-cardiac causes and no reinterventions. Left atrioventricular valvar regurgitation was moderate or mild in two patients, and right atrioventricular valvar regurgitation was mild in one patient. No patient had more than mild pulmonary regurgitation or a gradient across the right ventricular outflow tract in excess of 18 mm Hg. Our results demonstrate that primary repair of atrioventricular septal defect with tetralogy of Fallot can be performed with excellent early and mid-term results in young infants. Although it has been suggested that a technique utilizing oblique division of the anterosuperior bridging leaflet may lead to high rates of atrioventricular valvar regurgitation, medium-term atrioventricular valvar function in the present cohort of patients has been excellent.

Anomalous pulmonary venous return in the staged palliation of functional univentricular heart defects

BACKGROUND

Bidirectional cavopulmonary shunt and Fontan repair are now commonly performed in patients with a variety of forms of complex single ventricle, including those with anomalies of systemic, pulmonary, or systemic and pulmonary venous return. These anomalies are ideally dealt with during bidirectional cavopulmonary shunt, thereby minimizing the complexity of the eventual Fontan procedure.

METHODS AND RESULTS

Between March 1990 and March 1997, 32 patients with functional single ventricle and anomalous pulmonary venous return underwent operation at our institution. Five of 25 patients who underwent neonatal palliation died in the early postoperative period, all of whom had obstructed anomalous pulmonary venous return. Twenty-one patients have undergone bidirectional cavopulmonary shunt, including 7 in whom this was the primary palliative procedure. There was one early and two late deaths after the bidirectional Glenn procedure, two in patients with asplenia syndrome and none in patients with previously obstructed pulmonary venous return. Seven patients have undergone Fontan completion, 5 with an extracardiac conduit. There was one early death and one take-down to a classic Glenn shunt, both in patients who did not undergo the extracardiac conduit Fontan operation.

CONCLUSIONS

Anomalous pulmonary venous return can significantly complicate the management of the single-ventricle patient, with the major impact on survival coming in the neonatal period. Palliation with the aim of performing an extracardiac conduit Fontan procedure allows greater latitude and more streamlined management in this group of patients.

Additional pulmonary blood flow with the bidirectional Glenn anastomosis: does it make a difference?

BACKGROUND

The bidirectional cavopulmonary shunt has become a mainstay in the palliation of patients with a functional single-ventricle heart. However, there remain a number of unresolved issues regarding this procedure, many of which concern the response of the pulmonary vasculature to this unique circulatory physiology. Among the issues of debate are the role and effects of an additional source of pulmonary blood flow.

METHODS

Between January 1990 and April 1997, 160 patients underwent bidirectional cavopulmonary anastomosis. Median age at operation was 7.8 months, and age ranged from 24 days to 43 years. An additional source of pulmonary blood flow was included in 93 patients (58%). A retrospective review of our experience with this cohort was performed with a focus on the role of additional pulmonary blood flow.

RESULTS

Eight patients (5%) died in the early postoperative period, and the overall early failure rate (death or take-down) was 7.5% (n=12). Eleven other patients underwent early reoperation to decrease (n=8) or increase (n=3) the amount of pulmonary blood flow. Early survivors were followed up for a median of 23 months, during which time 5 patients died and 30 patients underwent Fontan completion. Including early and late mortality, actuarial survival rates at 1 and 2 years were 91% and 88%, respectively.

CONCLUSIONS

The bidirectional cavopulmonary shunt is a useful procedure in the early or intermediate-term management of patients with a functional univentricular heart. However, there is much still to be learned about this unique physiologic system. The role of accessory pulmonary blood flow remains unclear, as does the use of the bidirectional cavopulmonary shunt as long-term palliation. Pulmonary arteriovenous fistulas are a serious concern, especially in young patients with heterotaxy syndrome.

Pulmonary arteriovenous malformations in and out of the setting of congenital heart disease

BACKGROUND

Pulmonary arteriovenous malformations can occur in a variety of clinical situations, including liver disease, systemic disorders, or after palliation of congenital heart disease, with serious clinical consequences.

METHODS

We reviewed the potential mechanisms of this condition, diagnostic tools, and clinical management.

RESULTS

Contrast echocardiography is an important diagnostic modality, which has been shown to be more sensitive than pulmonary arteriography, especially when rapid contrast injection is used. The finding that pulmonary capillary vasodilation is observed in hepatopulmonary syndrome, in cirrhotic patients, and after congenital heart repair is strongly suggestive that an unidentified hepatic factor is involved in inhibiting the development of pulmonary arteriovenous malformations.

CONCLUSIONS

Prompt detection and treatment of pulmonary arteriovenous malformations is of utmost importance, to prevent serious clinical consequences. It may very well be the case that the etiology of arteriovenous malformations is multifactorial. We are now investigating the role of alterations of gene expression in the vascular remodeling that results in formation of pulmonary arteriovenous malformations.

Tetralogy of Fallot with major aortopulmonary collaterals: early total repair

Tetralogy of Fallot with pulmonary atresia and major aortopulmonary collaterals is a complex lesion distinguished by marked heterogeneity of pulmonary blood supply. Over the past two decades, investigators have developed various approaches to the management of this anomaly generally based on the concept of staged unifocalization of pulmonary blood supply. Although such approaches may represent an improvement on the natural history of this lesion, they remain inadequate for a substantial portion of patients born with tetralogy of Fallot and major aortopulmonary collaterals. Since 1992, our approach has been to perform one-stage complete unifocalization through a midline approach in all but a few extremely complicated patients. We aim to repair these patients early in infancy, with an emphasis on native tissue-tissue reconstruction, in order to optimize prospects for survival with a good functional outcome in as many patients as possible. In this review, we present our philosophy and our experience with unifocalization and repair in 72 patients.

Rare forms of isolation of the subclavian artery: echocardiographic diagnosis and surgical considerations

Isolation of the subclavian artery is an unusual anomaly in which the subclavian artery arises not from the aortic arch but from a pulmonary artery via an arterial duct. Such isolation most often occurs with a right aortic arch, and in lesions frequently associated with a right arch, such as tetralogy of Fallot. Since 1994, we have undertaken surgery in four young infants with isolated subclavian arteries and unusual associated anomalies, including one with atrioventricular septal defect and common valvar orifice, two with interruption of a left aortic arch and one with interruption of a right aortic arch. In both patients with interrupted left arch, the isolated subclavian artery was diagnosed preoperatively by echocardiography. We emphasize the significant surgical issues.

Partial biventricular repair for complex congenital heart defects: an intermediate option for complicated anatomy or functionally borderline right complex heart

BACKGROUND

Partial biventricular repair consists of bidirectional cavopulmonary anastomosis in the presence of separated systemic and pulmonary circulations, with antegrade flow of inferior caval return through an intact or reconstructed pulmonary outflow tract. This versatile procedure may be used as a definitive repair for patients with a functional right heart complex incapable of supporting an entire cardiac output or in patients with complicated anatomy.

METHODS

From July 1992 to April 1997, 23 patients (median age 5.2 years) underwent partial biventricular repair. In 15 of these cases the entire repair, including bidirectional cavopulmonary anastomosis, intracardiac repair, and right ventricular outflow reconstruction, was performed as a planned procedure at our institution. The other eight patients had previously been placed on a Fontan track and had undergone bidirectional cavopulmonary anastomosis; their circulations were converted to a partial biventricular circulation.

RESULTS

There were no early deaths. Complete atrioventricular block developed in two patients with straddling tricuspid valve. At a median follow-up of 17 months, there were no late deaths and three patients had undergone reintervention. Partitioning of the pulmonary arteries to create a classic Glenn anastomosis with antegrade flow to the left lung was performed in one case; another patient underwent an atrial septectomy, and the third patient required revision of tricuspid valve repair. All patients are in New York Heart Association functional class I.

CONCLUSIONS

Partial biventricular repair is a versatile strategy that can be used to manage a variety of forms of complex congenital heart disease. Cases for which the repair is useful include those in which complete biventricular repair is unlikely to be achieved because of limited size or function of the right side of the heart and those in which a patient with a ventricle capable of supporting inferior vena caval return was previously placed on a Fontan track.