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Biomedical subjects

F L Hanley

Publications and source records attributed to F L Hanley.

At least 91 records · Page 5Linked to original sources
PubMed1997

Modified Damus-Kaye-Stansel procedure for single ventricle, subaortic stenosis, and arch obstruction in neonates and infants: midterm results and techniques for avoiding circulatory arrest.

BACKGROUND: A modified Damus-Kaye-Stansel procedure is one of several options for palliation of single ventricle with subaortic obstruction, but results in neonates have been disappointing. In the presence of arch obstruction, this procedure is typically performed with circulatory arrest, which may contribute to neurologic insult. METHODS: Since 1990, a modified Damus-Kaye-Stansel procedure has been performed in 14 neonates and seven infants with single ventricle and subaortic stenosis, including 15 with arch obstruction. Diagnoses were double-inlet left ventricle (n = 12), tricuspid atresia (n = 2), and other forms of hypoplastic ventricle with subaortic obstruction (n = 7). Three patients underwent concurrent bidirectional Glenn shunt. In the most recent seven patients with arch obstruction, arch repair was achieved with an end-to-side anastomosis of the descending aorta to the ascending aorta with continuous upper body perfusion. RESULTS: One early death occurred among the 14 neonates (7%) and three among the infants, for an early mortality of 19%. At a median follow-up of 33 months, there were no late deaths or neurologic complications. Nine patients underwent subsequent bidirectional Glenn anastomosis, including three who had Fontan completion and one who later underwent conversion to a partial biventricular repair. One patient required a transplant for cardiomyopathy of unknown etiology. The remaining 12 patients are considered good candidates for Fontan completion. No patient has recurrent arch obstruction. Four patients have mild (n = 1) or trivial (n = 3) semilunar valvular regurgitation. CONCLUSION: The modified Damus-Kaye-Stansel procedure is an effective primary palliation for single ventricle and subaortic stenosis, with or without arch obstruction. Results are especially encouraging in neonates. Arch repair can be achieved without circulatory arrest to the brain.

Anastomosis, Surgical↗
PubMed1997

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.

Adolescent↗
PubMed1997

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.

Abnormalities, Multiple↗
PubMed1997

Outcomes after bidirectional cavopulmonary shunt in infants less than 6 months old.

OBJECTIVES: We sought to assess the results after bidirectional cavopulmonary shunt (BCPS) in infants < 6 months old and to identify risk factors for poor outcome. BACKGROUND: Although BCPS is a well established procedure for the palliation of patients with a single-ventricle heart, there have been very few reports of outcomes after BCPS in young infants. METHODS: Since 1990, 42 infants between 0.8 and 6.0 months of age (mean [+/-SD] 3.7 +/- 1.4) have undergone BCPS for primary (n = 16) or secondary (n = 26) palliation of tricuspid atresia (n = 13), hypoplastic left heart syndrome (n = 10) or other forms of functional single-ventricle heart (n = 19). Accessory pulmonary blood flow was included in 18 patients. Preoperative and perioperative data were gathered on retrospective review of patient records, and follow-up was conducted by means of direct physician contact or record review. RESULTS: The overall hospital mortality rate, including that associated with reoperations, was 4.8% (2 of 42 patients). Seven patients (17%) required reoperation related to the BCPS or pulmonary blood flow in the early postoperative period: Procedures included take-down of the BCPS in four patients, with one early death, and procedures to decrease pulmonary blood flow in three patients. Age < 1 month correlated significantly with early death and with early failure of the BCPS (death or take-down). Follow-up of the 37 patients discharged with intact BCPS was obtained at a mean +/-SD of 14.3 +/- 11.3 months postoperatively, during which time three patients died (at 6.5 +/- 2.5 months). The 2-year actuarial survival rate for patients undergoing BCPS at < 6 months of age was 86%. Overall freedom from death or take-down (including early and late events) was significantly lower in patients < 2 months old than in those > 2 months old. Four patients have undergone successful Fontan completion (18.3 +/- 2.9 months postoperatively), and one patient whose BCPS was taken down subsequently underwent successful restoration of a BCPS. CONCLUSIONS: Outcomes after BCPS in young infants are comparable to those in older infants and children. However, our current preference is to defer this procedure until after 2 months of age.

Actuarial Analysis↗
PubMed1997

Systemic venous collateral channels causing desaturation after bidirectional cavopulmonary anastomosis: evaluation and management.

OBJECTIVES: We sought to characterize the frequency, anatomic details and factors associated with the development of collateral channels between the superior and inferior vena caval systems after bidirectional cavopulmonary anastomosis. BACKGROUND: It is well known that systemic venous collateral channels often develop in patients who have undergone a classic Glenn shunt or bidirectional cavopulmonary anastomosis and that such collateral channels can lead to profound systemic desaturation. However, there have been few reports focusing on this problem. METHODS: Fifty-four patients (median age 1.4 years) who underwent bidirectional cavopulmonary anastomosis and had preoperative and postoperative angiograms available for review were studied retrospectively. Postoperative connections between the superior and inferior vena caval systems were identified and measured. Sites of collateral origin and entry from the superior and inferior venous systems, as well as the course taken in between, were recorded. RESULTS: At follow-up angiography performed 17 days to 46 months postoperatively, a total of 31 venous collateral channels were observed in 18 patients with a wide variety of primary morphologic diagnoses. The majority of these collateral channels (80%) originated from the brachiocephalic vein or its junction with the superior vena cava, and over half of them drained below the diaphragm. In patients who developed venous collateral channels, the mean transpulmonary pressure gradient early after bidirectional cavopulmonary anastomosis was higher (p = 0.005), and mean arterial oxygen saturation at follow-up was lower (p = 0.009). There were trends toward higher superior vena caval pressure early after the operation and at follow-up in patients with collateral channels and a higher likelihood of absent upper lobe pulmonary blood flow in these patients. Successful coll embolization of 10 collateral channels was performed in six patients, with a median increase in arterial oxygen saturation of 16%. CONCLUSIONS: Angiographically detectable systemic venous collateral channels develop after bidirectional cavopulmonary anastomosis in a substantial number of patients (33% in the present series) with a variety of forms of a functional univentricular heart. Patients with venous collateral channels can be treated successfully with coil embolization, but the indications for embolization will depend on individual circumstances.

Adolescent↗
PubMed1997

The double switch procedure for anatomical repair of congenitally corrected transposition of the great arteries in infants and children.

AIMS: To assess outcomes of anatomical repair (double switch procedure) in infants and children with congenitally corrected transposition of the great arteries. METHODS AND RESULTS: Between September 1993 and August 1996, 17 patients with congenitally corrected transposition underwent surgery at UCSF. Anatomical repair was performed in 11 of these patients, at ages ranging from 4.8 months to 7.8 years (median 3.2 years). The remaining six patients did not undergo anatomical repair due to unfavourable anatomy (n = 2), prior conduit repair (n = 2), biventricular dysfunction (n = 1), and isolated complete atrioventricular block (n = 1). The 11 patients who underwent anatomical repair make up the study group for the present report. All 11 patients had a malalignment ventricular septal defect, while pulmonary outflow tract obstruction was present in nine patients and significant tricuspid valve pathology or dysfunction was present in five. Anatomical repair was achieved with a Senning (n = 7) or a Mustard (n = 4) procedure combined with an arterial switch operation plus ventricular septal defect closure (n = 4), or a Rastelli procedure with left ventricle to aortic baffle and right ventricle to pulmonary artery conduit (n = 7). There was one early death and no patients developed surgical complete atrioventricular block. At a median follow-up of 22 months, there were no late deaths. Two patients required a total of three late reoperations, and all patients were asymptomatic on no cardiac medication. Follow-up echocardiography revealed normal biventricular function in all patients. CONCLUSIONS: Anatomical repair of corrected transposition can be achieved with low rates of early mortality and surgical heart block, and favourable mid-term results. Long-term follow-up will be necessary to determine if the double switch approach improves the natural history of corrected transposition when compared to less aggressive surgical approaches that leave the right ventricle in the systemic circulation.

Adult↗
PubMed1996

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.

Acute Disease↗
PubMed1996

Transesophageal echocardiography in fetal sheep. A monitoring tool for open and fetoscopic cardiac procedures.

BACKGROUND: Cardiac procedures in exteriorized fetuses or assisted by fetoscopy require monitoring capabilities not attended by conventional maternal transabdominal echocardiography. METHODS: We, therefore, assessed the potential of fetal transesophageal echocardiography (TEE) utilizing an intravascular ultrasound catheter (IVUC) for fetal cardiac monitoring. We inserted a 10-F-10-MHz IVUC into the esophagus in 12 exteriorized fetal sheep and by a fetoscopic approach in 4 fetal sheep. Cardiac events were observed. Heart rate, cardiac rhythm, patency of the foramen ovale and ductus arteriosus, and the width of the branch pulmonary arteries could be assessed in all fetuses. Ventricular contractility could be assessed only in fetuses weighing less than 2.5 kg. Larger fetuses did not allow adequate imaging of the apical portion of the ventricles because of limited tissue penetration of the IVUC. Fetal TEE permitted placing small guide wires in the cardiac atria and left ventricle. Short-lived premature beats following intracardiac manipulations of these wires could be observed by fetal TEE in all cases. RESULTS: At autopsy, no complications from IVUC insertion were observed in the exteriorized fetuses. Fetoscopic placement of the IVUC resulted in minor perioral skin erosion in two nonexteriorized fetuses. CONCLUSIONS: In conclusion, fetal TEE can be achieved with minor fetal injury and may provide useful information during open and fetoscopic cardiac procedures. Further improvements in IVUC design will permit the application of this technique to monitor human fetal cardiac procedures.

Animals↗
PubMed1996

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.

Anastomosis, Surgical↗
PubMed1996

Intraatrial baffle repair of isolated ventricular inversion with left atrial isomerism.

Isolated ventricular inversion with left atrial isomerism, partial anomalous pulmonary venous connection, and interruption of the inferior vena cava with azygos continuation to a right superior vena cava was diagnosed by echocardiography in a neonate. At 48 days of age, the patient underwent successful anatomic correction with redirection of flow from the superior vena cava and hepatic veins to the left-sided tricuspid valve, and flow from the pulmonary veins to the right-sided mitral valve. In the present report, the surgical techniques of this case are described, along with a survey of the surgical literature covering anatomic repair of isolated ventricular inversion.

Echocardiography↗
PubMed1996

Revision of previous Fontan connections to extracardiac or intraatrial conduit cavopulmonary anastomosis.

BACKGROUND: In patients who have received an atriopulmonary Fontan connection, complications such as right pulmonary vein obstruction, atrial arrhythmias, and thromboembolism are often secondary to right atrial enlargement. When such complications develop despite good ventricular function, there are few management options available. Extracardiac or intraatrial conduit cavopulmonary anastomosis, which improves central systemic venous flow patterns, avoids atrial distention, and does not involve the extensive atrial suturing required by other forms of cavopulmonary anastomosis, may provide relief for this group of patients. METHODS: Between October 1992 and October 1995, 7 patients presented 8 to 20 years after atriopulmonary connection with severe right atrial dilatation (7), Fontan pathway obstruction (4), progressive congestive heart failure (4), atrial tachydysrhythmias (3), right atrial thrombus (1), obstruction of right pulmonary veins by an enlarged right atrium (1), and subaortic stenosis (1). After evaluation of the options, they underwent revision of the atriopulmonary connection to extracardiac (5) or intraatrial (2) conduit cavopulmonary anastomosis. RESULTS: One patient with severe cachexia, in whom transplantation was contraindicated for social reasons, died in the early postoperative period of massive effusions. Two patients eventually required permanent pacing for atrial dysrhythmias (1) or complete heart block secondary to subaortic fibromuscular resection (1), and 2 demonstrated marked improvement in unstable preoperative rhythm disturbances. At a median follow-up of 17 months, 4 of the 6 survivors were functioning at higher New York Heart Association levels than preoperatively, and 1 had recently undergone heart transplantation. CONCLUSIONS: In properly selected patients with atrial complications, revision of a prior Fontan connection to extracardiac or intraatrial conduit cavopulmonary anastomosis appears to be a viable option.

Adolescent↗
PubMed1996

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.

Cardiac Catheterization↗
PubMed1996

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.

Adolescent↗
PubMed1996

Fetal model of single ventricle physiology: hemodynamic effects of oxygen, nitric oxide, carbon dioxide, and hypoxia in the early postnatal period.

BACKGROUND: In patients with single ventricle physiology, the distribution of flow to the systemic and pulmonary circulations, which are in parallel, largely depends on the relative resistances in the respective vascular beds. Although neonatal palliation in patients with single ventricle physiology has become more common, medical management during the perinatal and perioperative periods is often based primarily on personal and institutional experience and is complicated by the transition to postnatal life and the effects of cardiopulmonary bypass. The lack of an animal model that suitably mimics single ventricle physiology has impeded progress in this area. OBJECTIVE: The purpose of the current study was to investigate the effects of respiratory manipulations on pulmonary hemodynamics in the early neonatal period in a reproducible model of single ventricle physiology created in utero. METHODS: A 10 mm Damus-Kaye-Stansel aortopulmonary anastomosis was created in fetal sheep (n = 14) at 140 +/- 1.2 days' gestation, with pulmonary blood flow provided through a 5 mm aortopulmonary shunt after ligation of the main pulmonary artery distally. Two to 3 days after delivery at term, lambs (n = 11) underwent an open sternotomy and 30 minutes of deep hypothermic circulatory arrest. Both before and after bypass, respiratory manipulations, including administration of nitric oxide (80 ppm), 100% oxygen, 10% oxygen, and 5% carbon dioxide, were performed and hemodynamic variables were measured. RESULTS: Nitric oxide and oxygen caused a decrease in pulmonary vascular resistance and an increase in the pulmonary/systemic blood flow ratio, both before and after bypass. Hypoxia and carbon dioxide produced a significant rise in pulmonary vascular resistance and a significant drop in the ratio of pulmonary to systemic blood flow. CONCLUSIONS: Oxygen, nitric oxide, and carbon dioxide all appear to be useful means of manipulating pulmonary vascular resistance and pulmonary/systemic blood flow ratio in neonatal lambs with single ventricle physiology, but further investigation is necessary to understand their dose responsive effects and the effects of prolonged administration.

Animals↗
PubMed1996

Long-term outcome after fetal cardiac bypass: fetal survival to full term and organ abnormalities.

BACKGROUND: Earlier work suggests that fetal cardiac bypass is technically feasible but results in significant placental dysfunction. Many of the stimuli that initiate this placental dysfunction have been identified in the past several years and these involve fetal stress, extracorporeal surfaces, priming substances (maternal blood), and flow characteristics. Fetal survival with conventional methods of bypass has been far less than optimal. A novel fetal bypass circuit requiring no priming volume was designed incorporating an in-line axial flow pump (Hemopump, Johnson & Johnson Interventional Systems, Rancho Cordova, Calif.) and was demonstrated to have a marked beneficial effect on placental function. OBJECTIVE: The purpose of this study was to investigate the effect of this newly developed customized fetal bypass circuit on fetal survival and developing fetal organs. METHODS AND RESULTS: Nine fetuses at 122 to 126 days of gestation were subjected to fetal cardiac bypass via a transsternal approach, with a 16F single right atrial venous cannula and a 12F arterial cannula. Normothermic cardiac bypass was continued for 30 minutes at flow rates of 320 +/- 32 ml/kg. Of the nine fetuses, one fetus was stillborn 4 days after bypass and eight (89%) were delivered alive after progressing to term gestation. One lamb died of blunt trauma 1 day after birth. All other lambs (n = 7) thrived normally, and at 1 week of age they were subjected to autopsy. No gross hemorrhagic or thromboembolic lesions were detected in the organs examined including the brain. Microscopic examination of representative sections from all organs revealed mild pleural reaction in two lambs, and in two other lambs the hepatocytes showed evidence of mild increase in glycogen content, the significance of which is unknown in relation to fetal bypass. In one fetus that was aborted there was evidence of mild to moderate neuronal loss in the cerebral cortex. CONCLUSION: This study demonstrates that with improvements in fetal extracorporeal circuitry and techniques very favorable fetal outcome can be achieved. Further studies are necessary to evaluate the effects of bypass on fetal brain in an appropriate animal model. Advances in extracorporeal circuitry to suit the unique fetal physiology increase the possibility of future clinical application.

Animals↗