Edwin Petrossian

Incidence and implications of systemic to pulmonary collaterals after bidirectional cavopulmonary anastomosis

BACKGROUND Systemic to pulmonary arterial collaterals often develop after bidirectional cavopulmonary anastomosis (BCPA). It has been proposed that such collaterals may be related to perioperative outcome and duration of effusions after the modified Fontan procedure. However, the incidence and significance of collaterals after BCPA remain uncertain. METHODS To evaluate risk factors for, and significance of, such collaterals, we reviewed angiographic and clinical data for all 76 patients who underwent BCPA between January 1990 and June 1996 and had follow-up catheterization during or before 1997. RESULTS The median age at BCPA was 10 months, and the median duration from BCPA to follow-up catheterization was 18 months. Arterial collaterals were detected on follow-up catheterization in 45 patients (59%). Factors associated with collateral development included a prior right-sided systemic-to-pulmonary arterial shunt, lower pre-BCPA end-diastolic ventricular pressure and pulmonary vascular resistance, and use and duration of cardiopulmonary bypass during the BCPA operation. Fourteen of the 45 patients (30%) underwent coil embolization of the collaterals. Forty-three patients have undergone extracardiac conduit Fontan, with 1 early and 1 late death. Collaterals were present in 22 of these patients, 7 of whom underwent pre-Fontan embolization. The duration from BCPA to Fontan was longer in patients with collaterals, but these patients were not more likely to have prolonged effusions than those without, and the duration of tube thoracostomy was significantly shorter in patients with collaterals. Embolization of collaterals did not affect the duration of effusions. CONCLUSIONS Systemic-to-pulmonary arterial collaterals are common after BCPA. In contrast to prior reports, collaterals were not associated with a higher incidence of prolonged effusions after the Fontan procedure in our experience, and did not correlate with poor outcome.

One-stage complete unifocalization in infants: When should the ventricular septal defect be closed?

BACKGROUND The decision whether to close the ventricular septal defect at the time of unifocalization in patients with pulmonary atresia, ventricular septal defect, and major aortopulmonary collaterals may be difficult. The purpose of this study was to develop morphologic and physiologic methods to aid in deciding whether to close the ventricular septal defect in patients undergoing one-stage unifocalization. METHODS Between July 1992 and April 1996, 27 infants with pulmonary atresia, ventricular septal defect, and aortopulmonary collaterals were treated at our institution. Midline complete unifocalization was performed in 25 patients-the ventricular septal defect was closed in 17 and left open in eight. Two patients with severe distal collateral stenoses underwent staged unifocalization. Pulmonary artery and collateral sizes were measured from preoperative angiograms and used to calculate the indexed cross-sectional area of the total neopulmonary artery bed. An intraoperative pulmonary flow study previously validated with experiments in neonatal lambs was performed in six patients: the unifocalized neopulmonary arteries were perfused with a known flow and pulmonary artery pressures were recorded. RESULTS The neopulmonary artery index was greater in patients who underwent ventricular septal defect closure than in those who did not (p = 0.001), although the values did overlap. This index correlated with the postoperative right ventricular/left ventricular pressure ratio (p = 0.037). Mean pulmonary artery pressures obtained during the intraoperative flow study and after bypass were comparable. CONCLUSION The total neopulmonary artery index correlates with postrepair right ventricular/left ventricular pressure ratio and is useful in deciding when to close the ventricular septal defect if it is larger than 200 mm2/m2. The pulmonary flow study is helpful in deciding whether to close the ventricular septal defect in all patients.

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.

Pulmonary artery growth after bidirectional cavopulmonary shunt: is there a cause for concern?

OBJECTIVE Our objective was to analyze changes in pulmonary artery size after bidirectional cavopulmonary shunt. METHODS All 47 patients who underwent bidirectional cavopulmonary shunt between March 1990 and May 1995 who had preoperative and postoperative angiograms available for review were selected for study. This included 24 patients who had also undergone a modified Fontan operation. Clinical records were reviewed retrospectively and cross-sectional follow-up was obtained by direct physician contact. Angiograms were reveiwed, and the right and left pulmonary artery diameters were each measured at two locations: immediately distal to their origin and at the narrowest point. In addition, the lower lobe pulmonary artery branch was measured just distal to its origin. Cross-sectional areas (left, right, and total) at each point of measurement were indexed to body surface area. Angiographic and hemodynamic data were analyzed. RESULTS Changes in the various measures of pulmonary artery size after bidirectional cavopulmonary shunt varied considerably. On average the absolute diameters increased for all measures, but the increase in diameter was significant only for the lower lobe arteries. All pulmonary artery indices decreased on average, but these changes did not approach significance. Patients who underwent pulmonary artery augmentation at the time of bidirectional cavopulmonary shunt had significantly smaller pulmonary artery indices before pulmonary artery augmentation, relative to those who did not undergo pulmonary artery repair, and significantly greater changes (possibly to a large extent owing to pulmonary artery repair) in the right and left pulmonary artery index after bidirectional cavopulmonary shunt. Lower lobe indices did not differ preoperatively or exhibit different degrees of change in size between patients who did and did not undergo pulmonary artery repair. One patient died after Fontan completion (pulmonary artery index: 305 mm2/m2), and none of the factors analyzed correlated with Fontan outcomes. CONCLUSIONS A more appropriate measure of pulmonary artery growth is the indexed cross-sectional area of the lower lobe branch of the right and left pulmonary arteries, which is less likely to be altered surgically with systemic-pulmonary shunts, pulmonary artery repair, and the bidirectional cavopulmonary anastomosis itself. Pulmonary artery indices, including the lower lobe index, do not change significantly after bidirectional cavopulmonary shunt during medium-term follow-up and do not influence the Fontan outcome.

Fetoscopic and Open Transumbilical Fetal Cardiac Catheterization in Sheep Potential Approaches for Human Fetal Cardiac Intervention

BACKGROUND Shortening the prenatal disease course of severe aortic and pulmonary stenoses by balloon valvuloplasty may diminish their postnatal expression. The purpose of this study in fetal sheep was to assess the feasibility of fetoscopic and open transumbilical fetal cardiac catheterization guided by fetal transesophageal echocardiography to provide alternative approaches for human fetal cardiac intervention. METHODS AND RESULTS We studied a total of nine fetal sheep (95 to 103 days of gestation; term = 145 to 150 days) and performed transumbilical fetal cardiac catheterization by a minimally invasive fetoscopic (n = 6) or an open fetal surgical approach (n = 3). Monitored by fetal transesophageal echocardiography, with an 8F or 10F, 10-MHz intravascular ultrasound catheter we placed guidewires and interventional catheters via the umbilical arterial route into the fetal heart. In three of the fetuses, we created supravalvar pulmonary artery stenosis by open fetal cardiac surgery After fetal and maternal recovery, we exteriorized these fetuses and performed open transumbilical fetal cardiac catheterization with successful pulmonary arterial angioplasty in two. Three fetuses survived fetoscopic transumbilical catheterization for 1 or 2 days and died most likely of blood loss after sheath dislodgment (n = 1) or removal (n = 2). By securing the sheath insertion site with a suture, we prevented sheath dislodgment and minimized bleeding during sheath removal in three fetuses. These fetuses then survived fetoscopic transumbilical fetal cardiac catheterization for 1 to 2 weeks before being killed. CONCLUSIONS This study in fetal sheep demonstrates that fetoscopic and open transumbilical fetal cardiac catheterization are feasible and, guided by fetal transesophageal echocardiography, provide potential alternative approaches for human fetal cardiac intervention.

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.

Issues and outcomes in the management of supravalvar aortic stenosis

BACKGROUND Supravalvar stenosis of the aorta is an uncommon congenital cardiac anomaly that involves not only the supravalvar aorta but the entire aortic root. Despite considerable attention to the importance of maintaining the integrity of the aortic root during supravalvar reconstruction, there has been little focus on the management of other components of the aortic root and left ventricular outflow tract, including the aortic valve, subvalvar region, and coronary arteries. METHODS We reviewed the records of 36 consecutive patients with supravalvar aortic stenosis who underwent repair from 1992-1998 (median age, 4 years). Discrete stenosis was present in 29 patients, whereas the remaining 7 had the diffuse form of the disease. Associated anomalies of the aortic root and adjacent structures were present in 23 patients. The median pressure gradient across the left ventricular outflow tract was 70 mm Hg. Supravalvar stenosis was relieved by extended aortoplasty with a Y-shaped patch in 18 patients, resection of the stenotic segment of ascending aorta at the sinotubular junction with end-to-end anastomosis of the ascending aorta in 7, the Ross procedure in 4, and other techniques in 7. Additional procedures included aortic valvuloplasty in 10 patients, resection of subvalvar stenosis in 11, and procedures on the coronary arteries in 2. RESULTS There was 1 perioperative death, and no reoperations or other significant complications. During follow-up (median 33 months), there were no deaths and 3 reoperations for replacement of the aortic valve with a pulmonary autograft (n = 1) or mechanical prosthesis (n = 2). The median pressure gradient across the left ventricular outflow tract was 10 mm Hg. CONCLUSIONS In patients with supravalvar aortic stenosis, abnormalities of the aortic valve, subaortic region, and coronary arteries are frequently present as well. Management of these issues is as critical to the long-term outcome of these patients as reconstruction of the supravalvar aorta. Aggressive valvuloplasty may help decrease the incidence of late aortic valve replacement, whereas the Ross procedure may be a preferable approach in some patients with complex outflow tract obstruction.

Percutaneous fetal access and uterine closure for fetoscopic surgery : Lessons learned from 16 consecutive procedures in pregnant sheep

AbstractBackground: Maternal morbidity and preterm labor from fetal surgery might be minimized by a percutaneous technique for fetal access and uterine closure. Methods: In each of 16 ewes, we inserted three trocars percutaneously into the amniotic cavity using ultrasound and fetoscopic guidance. In six ewes, percutaneous uterine closure after the procedure was attempted. We assessed feasibility and acute complications of our technique during surgery and at autopsy. Results: We achieved percutaneous fetal access in 14 ewes and closed the uterus percutaneously in all six ewes attempted. Fetal injury was related to amnioinfusion or fixation of chorioamniotic membranes. Other complications were trocar dislodgment and damage to uterine wall and chorioamniotic membranes. The latter complication was prevented using balloon-tipped trocars. Conclusions: Percutaneous intraamniotic access and uterine closure for fetoscopic surgery can be achieved reliably with little maternal and fetal morbidity in sheep. Minor modifications are desired to apply this approach in humans.

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.

Homograft Valved Right Ventricle to Pulmonary Artery Conduit as a Modification of the Norwood Procedure

Background— The use of a right ventricle to pulmonary artery (RV-PA) conduit in the Norwood procedure has been proposed to increase postoperative hemodynamic stability. A valve within the conduit should further decrease RV volume load. We report our clinical experience with this modification. Methods and Results— From February 2002 through August 2005, we performed 88 consecutive Norwood procedures using RV-PA conduits. We used composite valved conduits made from cryopreserved homograft and polytetrafluoroethylene (PTFE) in 66 cases (54 pulmonary, 12 aortic homografts), other valved conduits in 14, and unvalved PTFE in 8 cases. Hospital survival was 88.6% overall and increased to 93.1% after the initial year. Early interventions were required in 18 patients (16 for cyanosis). Prestage II cardiac catheterization was performed at a mean age of 126 days. Mean Qp/Qs was 1, with mean aortic saturation 71%, mean O2 extraction 24%, and mean right ventricular end-diastolic pressure 9 mm Hg. Patient weight, use of an aortic homograft valve in the conduit, stage I palliation within the first year of our experience, and low O2 extraction and high transpulmonary gradient prestage II were risk factors for overall death. Early interventions were more frequent in aortic valve conduits compared with all other conduits. Conclusions— The valved RV-PA conduit was associated with low early mortality after the Norwood procedure. The majority of these patients had normal cardiac output and well-maintained RV function. There may be a higher risk for early conduit interventions and death when aortic valve homografts are used in the RV-PA conduit.