Hiranya A. Rajasinghe

Aortoventriculoplasty with the pulmonary autograft: The "Ross-Konno" procedure

BACKGROUND For patients with complex left ventricular outflow tract obstruction, including hypoplastic aortic anulus with or without severe diffuse subaortic stenosis, various aortoventriculoplasty procedures (e.g., Konno procedure and its modifications; extended aortic allograft root replacement) are important management options. In younger patients, however, reoperation for valve replacement is inevitably required, and anticoagulation issues pose additional problems. The pulmonary autograft provides a promising option for aortic valve replacement as part of the aortoventriculoplasty procedure in children. Long-term follow up shows that the pulmonary autograft functions well as the systemic arterial (neoaortic) valve and that valve growth occurs. METHODS Between July 1993 and May 1995, 11 patients 4 days to 17 years old (median 12 months) underwent aortoventriculoplasty with pulmonary autograft (Ross-Konno procedure). The diagnoses were aortic stenosis with or without subaortic stenosis (n = 8), Shone complex (n = 2), and interrupted aortic arch with subaortic stenosis (n = 1). On average, 1.9 previous interventions had been performed per patient, including a previous Konno procedure in one patient. The aortic root was replaced with a pulmonary autograft valve. The left ventricular outflow tract was enlarged with a Dacron polyester fabric patch in two patients, with an allograft aortic patch in two patients and a right ventricular infundibular free wall muscular extension harvested in continuity with the autograft in seven patients. RESULTS Intraoperative transesophageal echocardiographic assessment revealed mild aortic insufficiency in one patient. One patient had a residual left ventricular outflow tract gradient of 15 mm Hg. Significant complications were cardiac tamponade from bleeding (n = 1) and complete heart block necessitating a permanent pacemaker (n = 1). Follow-up ranged from 2 weeks to 16 months. To date, there have been no late deaths or reoperations. Follow-up echocardiography revealed mild autograft insufficiency in one patient and a 16 mm Hg residual left ventricular outflow tract gradient in one patient. CONCLUSIONS Initial experience suggests that aortoventriculoplasty with the pulmonary autograft is an excellent alternative for young patients with complex left ventricular outflow tract obstruction. Because the pulmonary autograft has been shown to grow after implantation, reoperation on the left ventricular outflow tract is likely to be avoided.

Long-term follow-up of truncus arteriosus repaired in infancy: A twenty-year experience

BACKGROUND There have been few reports of long-term follow-up after truncus arteriosus repair in infancy. METHODS A retrospective review was performed to assess long-term outcomes among 165 patients who survived the initial hospital stay after complete repair of truncus arteriosus since 1975. The median age at truncus repair over this 20-year experience was 3.5 months (range 2 days to 36 years), and 81% of patients were less than 1 year of age. Previous pulmonary artery banding had been performed in 15 patients, and two patients had undergone prior repair of interrupted aortic arch. Significant procedures performed along with truncus repair included truncal valve replacement (n = 10) or repair (n = 5) and repair of interrupted aortic arch (n = 4). RESULTS Patients were followed up for up to 20.4 years (median 10.5 years). Twenty-five patients were lost at cross-sectional follow-up, with a total of 67 patient-years of follow-up available on these patients. There have been 23 late deaths, eight of which occurred within 6 months of repair and 13 of which occurred within 1 year. Ten of the late deaths were related to reoperations. Actuarial survival among all hospital survivors was 90% at 5 years, 85% at 10 years, and 83% at 15 years and was essentially identical for infants alone. A significant independent risk factor for poorer long-term survival was truncus with moderate to severe truncal valve insufficiency before repair. During the follow-up period, 107 patients underwent 133 conduit reoperations. Median time to conduit reoperation was 5.5 years, and the only factor significantly associated with shorter time to conduit replacement was smaller conduit size at initial repair. In addition, 26 patients underwent 30 truncal valve replacements. Six patients required truncal valve replacement before any conduit-related reintervention, with two associated deaths. Actuarial freedom from truncal valve replacement among patients with no prerepair truncal valve insufficiency was 95% at 10 years. Actuarial freedom from truncal valve replacement was significantly lower among patients with truncal insufficiency before initial repair (63% at 10 years). At follow-up, all patients except three were in New York Heart Association functional class I. CONCLUSIONS Ten- to 20-year survival and functional status are excellent among infants undergoing complete repair of truncus arteriosus. Conduit replacement or revision is almost inevitably necessary in this group of patients.

Coarctation repair using end-to-side anastomosis of descending aorta to proximal aortic arch

BACKGROUND Recurrent aortic coarctation after primary operative repair in the neonate and small infant is seen most commonly within the first year of life. Inadequate removal of ductal tissue, failure to address hypoplasia of the aortic arch, and suture line tension have been cited as important factors in early recurrence. METHODS To address these issues, we have used a technique of coarctation resection and extended anastomosis of the descending aorta to the undersurface of the aortic arch. THe salient features of this approach include extensive mobilization of the aortic arch and neck vessels, careful trimming of all ductal tissue, ligation of the isthmus just beyond the left subclavian artery, and end-to-side anastomosis of the descending aorta to a separate incision in the undersurface of the aortic arch proximal to all tubular hypoplasia. Between July 1992 and January 1995, 19 consecutive neonates (median age, 13 days) and 4 consecutive infants under 3 months of age (median age, 69 days) with a mean peak systolic upper to lower extremity resting gradient of 27.9 +/- 16.9 mm Hg underwent repair of aortic coarctation and tubular hypoplasia of the arch. Other procedures performed at the time of repair included ligation of a patent ductus arteriosus (n = 19), pulmonary artery banding (n = 3), and closure of ventricular septal or atrial septal defect (n = 3). RESULTS There were no perioperative deaths. Early postoperative complication included a recurrent laryngeal nerve injury and a transient focal tonic clonic seizure. There was one late death, after a subsequent intracardiac surgical procedure, at a median follow-up of 16 months (range, 1 to 29 months). Twenty-one of 22 late survivors were free of recurrent aortic coarctation by echocardiography findings and clinical examination, with a median upper to lower extremity gradient of 0 mm Hg. Reintervention for recurrent aortic coarctation was not required in any survivor. CONCLUSIONS The technique described herein completely removes all potentially abnormal tissue from the aorta, including ductal tissue and all tubular hypoplastic tissue proximal to the coarctation site.

Trends in the Management of Truncal Valve Insufficiency

BACKGROUND The single semilunar valve in patients with truncus arteriosus frequently is dysplastic and dysfunctional. Truncal valve insufficiency has been associated with poor outcome. Although the management of truncal valve insufficiency has evolved over the years, approaches to this problem vary considerably and remain a serious dilemma in many cases. METHODS We reviewed the records of 89 patients with unrepaired truncus arteriosus and mild (n = 37), moderate (n = 33), or severe (n = 19) truncal valve insufficiency who were admitted to our institution between 1975 and 1995. Eight patients (7 neonates) with moderate or severe insufficiency died before surgical intervention, and 4 patients underwent palliative pulmonary artery banding. The remaining 77 patients underwent repair. The median age at repair was 3.2 months (range, 2 days to 15 years; 83% infants), and it decreased from 4 months between 1975 and 1985 to 1 month between 1986 and 1995. Truncal valve replacement (mechanical = 6, allograft = 4) was performed in 10 patients, and 5 patients underwent valve repair. RESULTS All 4 patients who underwent pulmonary artery banding died either early or late. The hospital (or 30-day) mortality rate after repair was 34% (26/77). At a median follow-up of 10 years, 11 hospital survivors had died, with overall 1- and 10-year actuarial survival rates of 56% and 48%, respectively, and poorer survival among patients with severe truncal valve insufficiency (p = 0.02). Late truncal valve replacement (n = 24) had been performed in 21 patients. Freedom from truncal valve replacement was better in patients with mild truncal insufficiency than in those with moderate or severe preoperative insufficiency (p < 0.001). Four late deaths were related directly to reoperation for truncal valve replacement or to prosthetic valve dysfunction. Three of the 4 neonates who received allograft root replacements died within 7 months of repair, and severe allograft valve insufficiency requiring replacement 1 year after operation developed in the fourth. CONCLUSIONS The prospects for patients with truncal valve insufficiency have been improving over time. Nevertheless, the results in patients with severe insufficiency continue to be poor.

Morphologic determinants favoring surgical aortic valvuloplasty versus pulmonary autograft aortic valve replacement in children

UNLABELLED The pulmonary autograft is being used with increasing frequency to replace the diseased aortic valve in the pediatric population. Attempted surgical aortic valvuloplasty with an unacceptable result and return to cardiopulmonary bypass for aortic valve replacement with a pulmonary autograft results in prolonged bypass time and increased potential for morbidity. Therefore, the ability to predict an unsuccessful outcome for valvuloplasty would be of significant clinical benefit. This issue is addressed in the present study. METHODS Twenty-two patients (median age 5.7 years, range 3 weeks to 14 years) with bicuspid (n = 11), tricuspid (n = 9), or quadricuspid (n = 2) aortic valves underwent valvuloplasty for aortic stenosis (n = 9), aortic regurgitation (n = 7), or a combination (n = 6). Previous related procedures included balloon aortic valvuloplasty (n = 3) and open surgical valvotomy (n = 1). Median pressure gradient across the aortic valve was 80 mm Hg. Surgical valvuloplasty techniques included thinning of leaflets (n = 18), commissurotomy (n = 15), suspension of reconstructed leaflet to the aortic wall (n = 10), closure of leaflet fenestration (n = 5), shortening of free edge of prolapsed cusp (n = 4), repair of torn leaflets (n = 3), and augmentation of scarred leaflets with autologous pericardium (n = 3). Concomitant subvalvular and supravalvular stenosis were repaired in nine and four patients, respectively. In five patients, during the same hospital stay, a failed valvuloplasty was converted into a valve replacement with a pulmonary autograft because of residual or resultant stenosis (n = 3) or regurgitation (n = 2). RESULTS No early or late deaths occurred. At a median follow-up of 16.3 months the median pressure gradient across the aortic valve in the 15 patients with preoperative stenosis or combined stenosis and regurgitation was 16 mm Hg (p < 0.01 versus preoperative gradient). Of the 22 patients, the aortic valve functioned normally (defined as < or = mild stenosis or regurgitation, or both) in 14 patients (including five patients with valve replacement); four patients had stenosis (gradients 40, 45, 60, and 60 mm Hg), two patients had regurgitation, and two patients had combined stenosis (gradients 40 and 50 mm Hg) and regurgitation. Three of the patients with recurrent stenosis underwent secondary surgical valvuloplasty without improvement. Outcome after valvuloplasty was examined according to valve structure: six of nine tricuspid valves functioned normally, whereas only three of 13 nontricuspid valves functioned normally (P = 0.07). Patients with a nontricuspid aortic valve and regurgitation had a high probability of requiring immediate valve replacement (P = 0.009). The actuarial freedom from significant native valve stenosis or regurgitation at 24 months was 82% for tricuspid valves and 36% for nontricuspid valves (P = 0.007). CONCLUSIONS (1) Surgical aortic valvuloplasty should be the preferred approach when the aortic valve is tricuspid. (2) In contrast, aortic valve replacement with a pulmonary autograft should be the preferred strategy in the presence of a nontricuspid aortic valve (especially when the aortic valve is regurgitant) and after failed surgical valvuloplasty.

Extending the limits of the Ross procedure

BACKGROUND The potential for growth and the proven long-term durability of the native pulmonary valve make it ideal for replacement of the diseased aortic valve, especially in growing children. The use of the autologous pulmonary valve can be further extended to patients with complex left ventricular outflow tract obstruction and to neonates and infants. METHODS Between June 1993 and May 1995, 35 patients underwent the Ross procedure at our center. Of these, 15 (43%) had complex left ventricular outflow tract obstruction and 7 (20%) were infants, including 3 neonates. The autologous pulmonary valve was implanted as a root replacement with coronary reimplantation in all patients. Additional left ventricular outflow tract procedures performed were ventricular myectomy in 7 patients and a Konno type aortoventriculoplasty in 11 patients. RESULTS There was one early death in a patient with borderline hypoplastic left heart syndrome. At a median follow-up of 9 months (range, 0.2 to 22 months) there were no late deaths or reinterventions. The autologous pulmonary valve function was excellent, with 1 (2.8%) patient having moderate insufficiency. CONCLUSIONS Autologous pulmonary valve is an excellent option for aortic valve replacement in all age groups. Its use can be readily extended to neonates, infants, and patients with complex left ventricular obstruction requiring additional left ventricular outflow tract procedures.

Reinterventions After Repair of Common Arterial Trunk in Neonates and Young Infants

OBJECTIVES To determine rates of reintervention after repair of common arterial trunk in the neonatal and early infant periods. BACKGROUND With improving success in the early treatment of common arterial trunk, the need for reinterventional procedures in older children, adolescents and adults will become an increasingly widespread concern in the treatment of these patients. METHODS We reviewed our experience with 159 infants younger than four months of age who underwent complete primary repair of common arterial trunk at our institution from 1975 to 1998, with a focus on postoperative reinterventions. RESULTS Of 128 early survivors, 40 underwent early reinterventions for persistent mediastinal bleeding or other reasons. During a median follow-up of 98 months (range, 2 to 235 months), 121 reinterventions were performed in 81 patients. Actuarial freedom from reintervention was 50% at four years, and freedom from a second reintervention was 75% at 11 years. A total of 92 conduit reinterventions were performed in 75 patients, with a single reintervention in 61 patients, 2 reinterventions in 11 patients and 3 reinterventions in 3 patients. Freedom from a first conduit reintervention was 45% at five years. The only independent variable predictive of a longer time to first conduit replacement was use of an allograft conduit at the original repair (p = 0.05), despite the significantly younger age of patients receiving an allograft conduit (p < 0.001). Reintervention on the truncal valve was performed on 22 occasions in 19 patients, including 21 valve replacements in 18 patients and repair in 1, with a freedom from truncal valve reintervention of 83% at 10 years. Surgical (n = 29) or balloon (n = 12) reintervention for pulmonary artery stenosis was performed 41 times in 32 patients. Closure of a residual ventricular septal defect was required in 13 patients, all of whom underwent closure originally with a continuous suture technique. Eight of 16 late deaths were related to reintervention. CONCLUSIONS The burden of reintervention after repair of common arterial trunk in early infancy is high. Although conduit reintervention is inevitable, efforts should be made at the time of the initial repair to minimize factors leading to reintervention, including prevention of branch pulmonary artery stenosis and residual interventricular communications.

Post–Cardiopulmonary Bypass Pulmonary Hypertension in Lambs With Increased Pulmonary Blood Flow A Role for Endothelin 1

BACKGROUND After cardiopulmonary bypass (CPB), pulmonary hypertension and its associated increased vascular reactivity are a major source of morbidity, particularly for children with increased pulmonary blood flow. Although post-CPB pulmonary hypertension is well described, its mechanisms remain incompletely understood. Plasma levels of endothelin 1. a potent vasoactive substance implicated in pulmonary hypertension, are increased after CPB. The purpose of the present study was threefold: to characterize the changes in pulmonary vascular resistance and vascular reactivity induced by hypothermic CPB; to investigate the effects of preexisting increased pulmonary blood flow on these changes; and to better define the role of endothelin 1 in the pathogenesis of post-CPB pulmonary hypertension. METHODS AND RESULTS Vascular pressures and blood flows were monitored in 14 1-month-old lambs with increased pulmonary blood flow (after in utero placement of an aortopulmonary shunt) and 6 age-matched control lambs. During the 2-hour study period after 105.3 +/- 20.6 minutes of hypothermic CPB the increase in pulmonary vascular resistance was significantly augmented in lambs with increased pulmonary blood flow compared with control lambs (P < .05). Pretreatment with PD 145065 (a nonselective endothelin receptor blocker; 50 micrograms.kg-1.min-1) completely blocked this increase in pulmonary vascular resistance and blocked the increase in pulmonary vascular resistance in response to acute alveolar hypoxia after CPB (96.3 +/- 88.5% versus -9.7 +/- 16.4%; P < .05). Plasma endothelin 1 levels increased after CPB in all lambs. CONCLUSIONS Preexisting increased pulmonary blood flow alters the response of the pulmonary circulation to hypothermic CPB; the increase in pulmonary vascular resistance induced by CPB is augmented in lambs with increased pulmonary blood flow. Pretreatment with endothelin 1 receptor blockers eliminated the increase in pulmonary vascular resistance and the pulmonary vasoconstricting response to alveolar hypoxia, suggesting a role for endothelin 1 in post-CPB pulmonary hypertension. Endothelin 1 receptor blockers may decrease morbidity in children at risk for pulmonary hypertension after surgical repair with CPB and warrants further study.

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.

Key role of the alternate complement pathway in hyperacute rejection of rat hearts transplanted into fetal sheep

Hyperacute rejection (HAR) mediated by xenoreactive natural antibodies (XNA), which are thought to develop in early infancy, is a major impediment to transplantation between widely disparate species. The ability to diagnose certain forms of congenital heart defects early in prenatal life suggests the potential for these defects to be corrected by cardiac transplantation, prior to the development of XNA and host immunocompetence. This study investigated whether discordant cardiac xenotransplantation into fetal and neonatal recipients might obviate HAR due to the relative lack of XNA. Six neonatal lambs at 3 days (n=3) or 7 days (n=3) of life, and two fetal lambs at 125 and 142 days of gestation (term = 145 days) received cardiac grafts from adult Wistar-Furth (275-350 g) rats. All eight cardiac xenografts showed clinical evidence of HAR, with rapid swelling, loss of contractility, and ecchymosis and a mean survival time of 12.5 +/- 6.4 min. Sections of explanted grafts showed classical histologic features of HAR, including interstitial hemorrhages, platelet microthrombi, and edema, without leukocyte infiltration. Immunopathology of grafts harvested from fetal recipients showed a lack of significant intragraft deposition of sheep IgM, IgG, or C1q, but widespread endothelial labeling for C3, factor B, and properdin. In contrast, grafts in neonatal recipients showed IgM, IgG, and C1q deposition, as well as C3, factor B, properdin, and terminal complement (C) components. Fibrin deposition and platelet thrombi were seen in both groups of recipients. Injection of cobra venom factor resulted in prolongation of cardiac xenograft survival in neonatal lambs (n=3) to 12 hr. Analysis by immunohistology showed that normal sera from neonatal and adult, but not fetal, sheep contained IgM and IgG XNA reactive with rat cells. In conclusion, rodent grafts transplanted into fetal sheep undergo HAR, likely through direct activation of the alternate pathway of C, whereas neonatal lambs acquire XNA in the very early postnatal period and reject rat hearts through activation of both the classical and alternate pathways of C. Thus, at least in some species combinations, cardiac transplantation during the early postnatal period, or even in utero, may still be subject to development of HAR.