A large scale temporal and spatial environmental DNA biodiversity survey of marine vertebrates in Brazil following the Fundão tailings dam failure

Seawater contains a wealth of genetic information, representing the biodiversity of numerous species residing within a particular marine habitat. Environmental DNA (eDNA) metabarcoding offers a cost effective, non-destructive method for large scale monitoring of environments, as diverse taxonomic groups are detected using metabarcoding assays. A large-scale eDNA monitoring program of marine vertebrates was conducted across three sampling seasons (Spring 2018, Autumn 2019; Spring 2019) in coastal waters of Brazil. The program was designed to investigate eDNA as a testing method for long term monitoring of marine vertebrates following the Fundão tailings dam failure in November 2015. While no baseline samples were available prior to the dam failure there is still value in profiling the taxa that use the impacted area and the trajectory of recovery. A total of 40 sites were sampled around the mouths of eight river systems, covering approximately 500 km of coastline. Metabarcoding assays targeting the mitochondrial genes 16S rRNA and COI were used to detect fish, marine mammals and elasmobranchs. We detected temporal differences between seasons and spatial differences between rivers/estuaries sampled. Overall, the largest eDNA survey in Brazil to date revealed 69 families from Class Actinopterygii (fish), 15 species from Class Chondrichthyes (sharks and rays), 4 species of marine and estuarine mammals and 23 species of conservation significance including 2 species of endangered dolphin. Our large-scale study reinforces the value eDNA metabarcoding can bring when monitoring the biodiversity of coastal environments and demonstrates the importance of collection of time-stamped environmental samples to better understand the impacts of anthropogenic activities.

DNA metabarcoding for diet analysis and biodiversity: A case study using the endangered Australian sea lion (Neophoca cinerea)

The analysis of apex predator diet has the ability to deliver valuable insights into ecosystem health, and the potential impacts a predator might have on commercially relevant species. The Australian sea lion (Neophoca cinerea) is an endemic apex predator and one of the world's most endangered pinnipeds. Given that prey availability is vital to the survival of top predators, this study set out to understand what dietary information DNA metabarcoding could yield from 36 sea lion scats collected across 1,500 km of its distribution in southwest Western Australia. A combination of PCR assays were designed to target a variety of potential sea lion prey, including mammals, fish, crustaceans, cephalopods, and birds. Over 1.2 million metabarcodes identified six classes from three phyla, together representing over 80 taxa. The results confirm that the Australian sea lion is a wide-ranging opportunistic predator that consumes an array of mainly demersal fauna. Further, the important commercial species Sepioteuthis australis (southern calamari squid) and Panulirus cygnus (western rock lobster) were detected, but were present in <25% of samples. Some of the taxa identified, such as fish, sharks and rays, clarify previous knowledge of sea lion prey, and some, such as eel taxa and two gastropod species, represent new dietary insights. Even with modest sample sizes, a spatial analysis of taxa and operational taxonomic units found within the scat shows significant differences in diet between many of the sample locations and identifies the primary taxa that are driving this variance. This study provides new insights into the diet of this endangered predator and confirms the efficacy of DNA metabarcoding of scat as a noninvasive tool to more broadly define regional biodiversity.

Semilunar valve switch procedure: autotransplantation of the native aortic valve to the pulmonary position in the Ross procedure

BACKGROUND

The Ross procedure has gained wide acceptance in young patients with aortic valve disease. The durability of the pulmonary autograft in the aortic position has been proved, with up to 24 years of follow-up. The homograft pulmonary valve, however, has limited longevity. To circumvent this problem we harvested, repaired, and reimplanted the native aortic valve with intact commissures in the pulmonary position in 13 patients undergoing the Ross procedure for aortic insufficiency.

METHODS

The cause of aortic insufficiency was rheumatic in 6 patients, congenital in 4, post-aortic valvotomy in 2, and bacterial endocarditis in 1. Patient age ranged from 5 to 45 years (mean, 17+/-9 years). Root replacement technique with coronary artery reimplantation was used. In the first 4 patients, the native aortic valve was sutured into the right ventricular outflow tract, and a polytetrafluorethylene patch was used to reconstruct the main pulmonary artery. In the last 9 patients, the aortic valve and polytetrafluorethylene patch were made into a conduit by another surgeon while the left-sided reconstruction was performed.

RESULTS

All patients had marked reduction of left ventricular dilation and good function of the reimplanted native aortic valve, with up to 50 months of follow-up (mean, 29.9+/-14.2 months; range, 12 to 50 months). Two patients died 15 and 26 days, respectively, of a false aneurysm rupture at the distal aortic anastomosis. In the remaining 11 patients, 9 (82%) had mild or absent, and 2 (18%) had mild to moderate, neoaortic valve regurgitation. Similarly, 9 patients (82%) had mild or absent, and 2 (18%) had mild to moderate, neopulmonary valve regurgitation. Mild neopulmonary valve stenosis was present in 6 patients (54%) (mean gradient, 29+/-4 mm Hg; range, 25 to 35 mm Hg). All surviving patients are in functional New York Heart Association functional class I.

CONCLUSIONS

We conclude that use of the native aortic valve with the Ross procedure makes the procedure attractive and potentially curative. The diseased aortic valve works well in the pulmonary position because of lower pressure and resistance. The valve leaflets should remain viable and grow in both the pulmonary and aortic positions because they derive nutrition directly from the blood.

Clinical improvement after revision in Fontan patients

BACKGROUND

Arrhythmias, decreased exercise tolerance, or malabsorption will develop in a significant number of Fontan patients. Fontan revision consisting of creation of lateral atrial tunnel, reconnection of the Glenn shunt when present, or both appears to improve these patients.

METHODS

Over a 34-month period, 9 patients underwent Fontan revision. The mean age was 11 +/- 5 years and the mean interval from Fontan operation to revision was 3 +/- 2 years. The reason for revision included marked impairment in exercise capacity, inability to go to school consistently, and chronic fatigue in 6 patients, 3 of whom also had serious atrial arrhythmias. Five of the 6 patients had a classic Glenn shunt. The mean right atrial pressure was greater than the pressure of the Glenn shunt (20 +/- 1.6 versus 17 +/- 0.8 mm Hg). Three of the 6 patients also showed a significant gradient between the right or left pulmonary artery wedge and ventricular end-diastolic pressure, indicating pulmonary vein obstruction from the bulging atrial septum or partitioning patch (13 +/- 3 versus 6.8 +/- 1 mm Hg). The remaining 3 patients had revision because of malabsorption (1), hepatomegaly and obstructed right pulmonary veins from bulging atrial septum (1), and tricuspid insufficiency (1). Fontan revision was accomplished with creation of a lateral atrial tunnel and Glenn reconnection in 6 patients, Glenn reconnection in 2, and creation of a lateral atrial tunnel in 1. Four patients had additional procedures.

RESULTS

One patient died of Pseudomonas pneumonia. Early extubation, chest tube removal, and postoperative hospital discharge were accomplished in 8 patients (mean = 1.4 +/- 1, 2.8 +/- 1, and 8 +/- 3 days, respectively). One patient died 8 months postoperatively of brain damage after ventricular fibrillation from attempted cardioversion for atrial flutter. The remaining patients had marked improvement in exercise capacity with ability to consistently go to school, improvement in duration and tolerance to arrhythmias on less medication, and resolution of malabsorption up to 37 months postoperatively (mean, 20 +/- 12 months).

CONCLUSIONS

We conclude that creation of lateral atrial tunnel with excision of a bulging atrial septum or atrial partitioning patch that causes pulmonary venous obstruction, reconnection of the Glenn shunt, which allows better distribution of flow based on the pulmonary vascular bed and resistance of each lung, or a combination of these procedures will improve Fontan patients.

Energy expenditure at rest and during exercise in nonobese female cyclical dieters and in nondieting control subjects

The purpose of this research was to determine if resting energy expenditure (REE) and exercise energy expenditure (EEE) differed between nonobese female cyclical dieters (n = 11) and nondieting control subjects (n = 12). Dieters were defined as having intermittent periods of caloric restriction (less than or equal to 4184 kJ/d, or less than or equal to 1000 kcal/d) for greater than or equal to 7-10 d four times in the preceding year. Dieters were significantly (P less than 0.01) heavier (66 vs 57 kg) and fatter (26% vs 21% body fat) than controls subjects whereas fat-free tissue was similar in both groups. Dieters had significantly (P less than 0.003) lower relative REE than did control subjects (2.8 vs 3.1 mL O2.kg-1.min-1; 79 vs 92 kJ.kg body wt-1.d-1, or 19 vs 22 kcal.kg body wt-1.d-1) but absolute REE (kJ/d, or kcal/d) was similar. Regardless of the workload examined, relative EEE was significantly (P less than 0.009) lower in dieters than in control subjects whereas absolute EEEs were similar at each workload. Results indicate an increased efficiency of food utilization during exercise in dieters but no difference in absolute REE. In addition, repeated bouts of dieting may alter body composition.

Transposition of the great arteries with intact ventricular septum. Arterial switch in the first month of life

Twenty-three infants with simple transposition of the great arteries and intact ventricular septum were operated on from October 1983 to October 1986. The age at operation in 22 infants ranged from 2 to 21 days and in one was 35 days (mean 9.82 +/- 6.86 days). The infants were evaluated with cardiac catheterization at 1 to 27 days of age. Twenty-two infants had balloon atrial septostomy, and 22 received prostaglandin E1 infusion. The left ventricular diastolic wall thickness, assessed by M-mode echocardiograms, varied between 2.8 and 4 mm. There were two hospital deaths in this group of 23 infants (mortality 8.6%), and there were no late deaths. All surviving patients are doing well clinically. One patient had asymptomatic nonsustained ventricular tachycardia necessitating phenytoin. Postoperative echocardiographic assessment performed on 15 patients at 0.93 +/- 0.61 years of age and cardiac catheterization and angiographic studies on seven patients at 1.07 +/- 0.13 years after operation revealed excellent ventricular performance, good semilunar valve function, and mild gradient at the right ventricular outflow with a mean right ventricular pressure of 37.4 +/- 4.1 torr.

Arterial switch in simple and complex transposition of the great arteries

Arterial switch for repair of transposition of the great arteries was performed on 53 patients since October 1983. These patients were divided into three groups: group I, 25 infants with an intact ventricular septum who had primary repair in the first month of life (2 to 34 days of age, mean 9.7 +/- 6.6); group II, 13 patients with an intact ventricular septum who had anatomic repair after a preliminary procedure (pulmonary artery banding in 13, shunt in 10, atrial septectomy in 1); and group III, 15 infants with transposition of the great arteries and ventricular septal defect. In group III, six patients had Taussig-Bing abnormality, nine had previous pulmonary artery banding, three had coarctation of the aorta repaired earlier in life, and four were less than 2 weeks old. Overall early mortality was 9.4% (5/53: group I 8%, group II 7.6%, group III 13.3%). Two late deaths occurred in group II 10 and 12 weeks postoperatively after infection and high fever. A third late death 18 weeks postoperatively was due to aspiration in an infant with Goldenhar's syndrome. Mortality and morbidity decreased significantly after an initial learning period (no deaths from July 1985 to March 1987 overall, and none in the last 15 infants operated on in group I). The surviving 45 patients are doing well. All have normal sinus rhythm. Two had transient asymptomatic arrhythmias. Left and right ventricular function assessed by echocardiogram and postoperative cardiac catheterization were within normal ranges in all but two patients, one with pulmonary artery stenosis and one (Taussig-Bing abnormality with two large ventricular septal defects) with severe pulmonary vascular disease (9.6 units) observed before anatomic repair. The right ventricular pressure at catheterization ranged from 27 to 42 mm Hg in 12 patients and was 55 mm Hg in two. There was no aortic stenosis. Aortic insufficiency was trivial in three patients and mild in one. We conclude that excellent results can be obtained with arterial switch for transposition of the great arteries with or without ventricular septal defect, especially in neonates.

Development of neo-coarctation in patients with transposed great arteries and hypoplastic aortic arch after Lecompte modification of anatomical correction

We report on three patients with kinking in the proximal aortic arch that developed after Lecompte modification of the arterial switch operation. Two patients had a previous subclavian patch repair of coarctation of the aorta and had an associated hypoplasia of the transverse aortic arch, and one patient had hemodynamically mild coarctation at the anatomical repair. A severe pressure gradient across the kinked area ("neo-coarctation") necessitating reoperation developed in one patient. The acute arch angulation appears to be due to an excessive posterior displacement of the ascending aorta by the anterior relocation of either the right or left main pulmonary artery branch from underneath the aortic arch. A foreshortened and frequently hypoplastic transverse aortic arch, a common association with coarctation of the aorta, appears to be especially vulnerable to the development of "neo-coarctation" after the Lecompte modification of the anatomical repair of transposed great arteries.

Factors that exaggerate the deleterious effects of pulmonary insufficiency on the right ventricle after tetralogy repair. Surgical implications

Postoperative cardiac catheterization data of 74 patients with pulmonary insufficiency after tetralogy repair were analyzed. Two groups were identified: Group A, 26 patients with normal right ventricular function (ejection fraction 95% +/- 5.5%, end-systolic volume 110% +/- 17% of predicted normal) and Group B, 48 patients with right ventricular dysfunction (ejection fraction 80% +/- 18% [p less than 0.001], and end-systolic volume 218% +/- 75% of predicted normal [p less than 0.001]). There was no significant difference between the two groups with respect to frequency of previous palliative procedures, age at operative repair, operative techniques, methods of myocardial protection, and follow-up period. Right ventricular dysfunction in Group B was associated with significant distal pulmonary stenosis (right ventricle-pulmonary artery pressure gradient 28 +/- 13 torr in Group A versus 55 +/- 20 torr in Group B, p less than 0.001), moderate pulmonary regurgitation (regurgitant fraction 18% +/- 11% in Group A versus 32% +/- 10% in Group B, p less than 0.001), and large transannular outflow patch (ratio of patch diameter to descending aorta diameter 1.31 +/- 0.16 in Group A versus 2.50 +/- 0.28 in Group B, p less than 0.001). Pulmonary valve insertion was performed in 42 patients in Group B. Eighteen had subsequent cardiac catheterization. Right ventricular function recovered completely (end-systolic volume 122% +/- 24%, and ejection fraction 92% +/- 7% of predicted) in five of six patients (83%) who had valve insertion within the first 2 years after tetralogy repair. In contrast, right ventricular function remained abnormal in all 12 patients who had valve insertion later than 2 years after tetralogy repair (p less than 0.05). Patients with residual pulmonary stenosis and/or a large transannular outflow patch are at risk for the development of right ventricular dysfunction from pulmonary insufficiency after tetralogy repair. Early correction of these residual lesions and control of pulmonary insufficiency may prevent long-term deterioration in right ventricular function.

Fontan type operation for complex lesions. Surgical considerations to improve survival

Twenty-five of 49 patients who underwent a Fontan type operation had complex lesions other than tricuspid atresia with ventriculoarterial concordance. Three patients had significant subaortic stenosis. Thirty-four palliative operations, including nine Glenn shunts, were performed before the Fontan operation. Direct atriopulmonary anastomosis was performed in 21 patients. In four, valved conduits were used. Twelve patients had right atrioventricular valve patch closure (three had running and nine had interrupted suture technique). On the basis of the presence of increased or decreased pulmonary blood flow before any surgical intervention, patients were divided into Group 1 (previous pulmonary artery banding, N = 8) and Group II (pulmonic stenosis, N = 17). Postoperatively, in Group I, 87% had significant effusions, mean right atrial pressure was higher (20.6 +/- 6.5 torr), and hospital stay longer (31 days). In Group II, 40% had significant effusions, mean right atrial pressure was lower (16.5 +/- 4.3 torr), and hospital stay shorter (15 days). Significant atrioventricular valve patch disruption occurred in three patients (two had running suture technique), and conduit occlusion occurred in two. Four patients (three with subaortic stenosis and pulmonary artery banding) without an established Glenn shunt required Fontan takedown for persistent low cardiac output, two of whom died (2/25 or 8%). There were three late deaths (3/23 or 13%). Nineteen of 20 surviving patients observed from 2 months to 6 years are doing well. We believe that early Fontan takedown in patients with persistent low cardiac output, interrupted suture technique for atrioventricular valve closure, avoidance of valved conduits, and a preliminary Glenn shunt in patients with pulmonary artery banding and/or subaortic stenosis can further improve the results with the Fontan operation for complex lesions.

Persistent low cardiac output after the Fontan operation. Should takedown be considered?

Four of 44 patients who had undergone the Fontan operation had persistent low cardiac output necessitating takedown of the shunt 6 to 65 hours (average 23 hours) postoperatively. All four were in a group of 22 patients with complex lesions other than tricuspid atresia with ventriculoarterial concordance. The development of postoperative right atrial hypertension (average 24 torr), hepatomegaly, marked ascites, and decreasing lung compliance led to severe systemic hypotension with systolic arterial pressure ranging from 55 to 82 torr (average 68 torr), persistent metabolic acidosis, and oliguria despite massive colloid and crystalloid infusions (11,000 ml/m2/24 hr) and inotropic support. At reoperation the atriopulmonary anastomosis, which was found to be wide open, was taken down and an atrial septal defect was created in all patients. Three patients were left with a Glenn shunt and an aortopulmonary shunt to the left lung. One patient had bilateral aortopulmonary shunts. Two patients who survived reoperation had immediate postoperative improvement in systolic arterial and mean right atrial pressure (average 100 torr and 11.5 torr, respectively). Both are well 5 months and 4 years later. Repeat Fontan operation remains a possibility with acceptable risks because of the presence of the Glenn shunt in both patients. We believe that takedown should be considered in patients with persistent low cardiac output after the Fontan operation.

Effects of elevated coronary sinus pressure on left ventricular function after the Fontan operation. An experimental and clinical correlation

An experimental model was devised to evaluate the effects of elevated coronary sinus pressure on left ventricular performance. Thirteen mongrel dogs were used. The coronary sinus was cannulated and its entire blood flow diverted into a reservoir. The pressure in the coronary sinus was increased from 5 to 25 torr by elevating the drainage reservoir in a stepwise fashion. Cardiac index, coronary arteriovenous difference, rate of rise of left ventricular pressure, left ventricular systolic time intervals, and coronary blood flow were measured. When the coronary sinus pressure reached 15 torr, there was a significant decrease in cardiac index (3.60 +/- 0.5 to 2.70 +/- 0.6 L/min/m2, p less than 0.001), coronary blood flow (13.7 +/- 3.1 to 7.0 +/- 2.1 ml/min, p less than 0.001), rate of rise of left ventricular pressure (1,567 +/- 275 to 1,331 +/- 314, p less than 0.05), and an increase in coronary arteriovenous difference (62.8% +/- 9.3% to 70.5% +/- 5.4% saturation, p less than 0.03). These experimental results were correlated with postoperative catheterization findings in 24 patients with the Fontan procedure. Patients with a mean right atrial pressure less than 15 torr had a left ventricular ejection fraction of 93% +/- 6% of predicted, whereas patients with a right atrial pressure of 15 torr or more had a left ventricular ejection fraction of 75% +/- 13% of predicted (p less than 0.001). These experimental and clinical data strongly suggest that elevated coronary sinus pressure has deleterious effects on ventricular function after the Fontan procedure. Modifications of the procedure, such as using the rudimentary right ventricle when feasible or diverting coronary sinus flow to the pulmonary venous atrium, might decrease coronary sinus hypertension and improve long-term results.

The Damus-Stansel-Kaye procedure. Should the aortic valve or subaortic valve region be closed?

Two patients (one with transposition of the great arteries and another with Taussig-Bing anomaly) underwent the Damus-Stansel-Kaye procedure (Group I). Significant aortic valve insufficiency developed postoperatively in both patients. In contrast, seven patients with a univentricular heart and subaortic stenosis from a variety of reasons underwent creation of an aortopulmonary window (Group II), a procedure very similar to the proximal main pulmonary artery-aortic root anastomosis of the Damus-Stansel-Kaye procedure. Aortic valve insufficiency had not developed after up to 7 years of follow-up in this group (average 43 months). Postoperative angiograms suggest that aortic valve incompetence in Group I may have been caused by prolapse of the aortic valve. The valvular structures are subjected to high systolic pressures and face a dilated, low-pressure right ventricle. Aortic root distortion may have contributed, as well. In Group II patients, the aortic valve structures face a small, thick-walled chamber. The orientation of the aortic valve vis-a-vis the right ventricle changed postoperatively in Group I but not in Group II patients. Our experience suggests that the aortic valve or subaortic valve region should be closed at the initial repair in patients with low pulmonary vascular resistance who are undergoing the Damus-Stansel-Kaye procedure, to minimize the need for reoperation for aortic valve insufficiency.

Long-term results of porcine valve insertion for pulmonary regurgitation following repair of tetralogy of Fallot

Between January 1975 and January 1985, 49 patients, aged 2 to 20 years, underwent porcine valve insertion for control of pulmonary regurgitation following repair of tetralogy of Fallot. In 9 patients the valve was placed at the time of the repair; in the remaining 40, valve insertion was performed 2 to 5 years postoperatively. The primary indications for valve implantation included progressive cardiomegaly and evidence of right ventricular (RV) dilatation or dysfunction. Operative technique emphasized ample enlargement of the RV outflow tract and main pulmonary artery to allow for insertion of a large valve and prevention of turbulence or stenosis. There was 1 hospital death (2%). Follow-up is available on remaining patients 1 to 10 years postoperatively. Considerable prosthetic valvar stenosis or regurgitation occurred in 7 patients (14%) 3 to 8 years following insertion, including one after subacute bacterial endocarditis. The complication-free actuarial life was 82%, and the functional actuarial life was 84% at 10 years for the prosthesis. The data suggest that the porcine valve has a good long-term durability when inserted in the pulmonary position in pediatric patients.

Hemodynamic effects of intravenous nitroglycerin in pediatric patients after heart surgery

Twenty patients with congenital heart disease, ages 8 months to 6 years, received 1 to 5 micrograms/kg/min iv nitroglycerin after intracardiac repair to assess the hemodynamic effects of, and the pulmonary vascular response to, the drug in pediatric cardiac patients. Before surgery all patients had systemic-to-pulmonary blood flow ratios equal to or greater than 2.5:1. The pulmonary arterial pressure (PAP) was equal to aortic pressure in 14 patients and normal in six. The pulmonary vascular resistance (PVR) was elevated (more than 4 units) in five patients. After surgery, the right and left atrial pressures, PAP, and cardiac index were measured by thermodilution, and the systemic vascular resistance (SVR) and PVR were calculated. Intravenous nitroglycerin produced a significant drop in SVR at higher doses only (1602 +/- 359 to 1590 +/- 324 dynes X sec X cm-5, p = NS, at 2 micrograms/kg/min vs 1602 +/- 359 to 1247 +/- 417 dynes X sec X cm-5, p less than 0.01, at 5 micrograms/kg/min). Similarly, improvement in cardiac index was apparent only at higher doses (3.33 +/- 1.25 to 3.49 +/- 0.90 liters/min/m2, p = NS, at 2 micrograms/kg/min vs 3.33 +/- 1.25 to 3.82 +/- 0.98 liters/min/m2, p = NS, at 5 micrograms/kg/min). Also, the effect on the pulmonary vascular bed was most marked at higher doses and in patients with elevated PAP (175 +/- 27 to 148 +/- 28 dynes X sec X cm-5, p = NS, in patients with normal PAP vs 305 +/- 78 to 214 +/- 76 dynes X sec X cm-5, p less than .001, in patients with elevated PAP).(ABSTRACT TRUNCATED AT 250 WORDS)

Bone changes from prostaglandin therapy

Prostaglandin E therapy in infants causes periosteal elevation. Although the changes usually take 30-40 days to become visible, we have seen them as early as nine days. In 15 infants who had prostaglandin E therapy for over six days, three developed periosteal elevation. Three other cases are described in greater detail, with long-term follow-up in two in which the bone remodeled to normal. Gallium scan in one showed increased uptake in areas involved. The periosteal cloaking may mimic Caffey disease but the pattern of involvement is different, since the mandible, which is commonly affected in Caffey disease, is rarely involved in prostaglandin E therapy.

Modified Blalock-Taussig shunt in newborn infants

The modified Blalock-Taussig shunt, interposing an expanded polytetrafluoroethylene graft between the subclavian and pulmonary arteries, was performed in 30 neonates with a mean age of 8.8 days and a mean weight of 3.14 kg. Underlying lesions included severe tetralogy of Fallot or its variant (N = 10), transposition complex (with pulmonary stenosis or atresia) (N = 6), single ventricle equivalents (with pulmonary atresia or stenosis) (N = 9), and pulmonary atresia with intact ventricular septum (N = 5). The mean preoperative arterial oxygen tension prior to prostaglandin E1 therapy was 29.5 torr. The shunt was performed through a right thoracotomy in 18 patients, through a left thoracotomy in nine, and through a median sternotomy in three. A 5 mm graft was used in 21 patients and a 6 mm graft in nine patients. The mean postoperative arterial oxygen tension was 64.1 torr (p less than 0.001). The incidence of early shunt occlusion was 3.3% and the hospital mortality was 3.3%. Actuarial functional life of the shunt (no death or reoperation related to shunt failure) was 91% at 3 years' follow-up. Nine patients were recatheterized. There was no distortion of the pulmonary artery. The ratios of the diameter of the right pulmonary artery and pulmonary valve anulus to that of the descending aorta increased after the operation by 50% (p less than 0.001) and 52% (p less than 0.05), respectively. Our experience indicates that the modified Blalock-Taussig shunt has an excellent function, offers several technical advantages, and lacks most of the drawbacks of other systemic-pulmonary artery shunts. It may be the shunt of choice in patients less than 1 month of age.

Transient neonatal tricuspid regurgitation: possible relation with premature closure of the ductus arteriosus

Normal fetal circulation requires patency of the ductus arteriosus. Prenatal ductal closure causes profound circulatory changes, such as massive tricuspid regurgitation. After delivery, the clinical picture of these severely distressed cyanotic newborns usually improves rapidly as the circulation is no longer dependent on ductal patency after onset of respiration. This case report deals with a newborn infant with severe tricuspid regurgitation and a large atrial right to left shunt who was treated with prostaglandin E1 infusion at 12 hours of age and in whom cardiac angiography revealed no evidence of either patent or functionally closed ductus arteriosus and no anatomic cardiac abnormalities at 30 hours of age. On the basis of physiologic and morphologic observations in this infant, the possible role of premature ductal narrowing or closure in the pathogenesis of transient neonatal tricuspid regurgitation is discussed. It is recommended that documentation of ductal presence or absence should become part of the diagnostic evaluation of newborns with transient tricuspid regurgitation.

Unusual mitral valve abnormalities complicating surgical repair of endocardial cushion defects

A review of 155 cases of surgically repaired endocardial cushion defects revealed 16 patients (10%) with additional unusual mitral valve abnormalities that complicated the surgical procedure. Eight patients had accessory mitral valve tissue that connected the anterior and posterior leaflets to form a double-orifice valve (Group I). In four (50%), the lesion was associated with intermediate atrioventricular canal and small left ventricle; all four died following repair. In the other four, it was associated with ostium primum defect; all survived and are well. A single papillary muscle in the left ventricle was present in six patients (Group II). Two had intermediate atrioventricular canal and both died postoperatively. The other four had complete endocardial cushion defect and three are well following the operation. Perforation of the valve leaflets was present in two patients with ostium primum (Group III). Both patients are well postoperatively. Modification of the surgical technique is required to effect satisfactory repair. The bridge connecting the posterior and anterior leaflets of the mitral valve should be left undisturbed. Otherwise, severe regurgitation may result. In patients with single papillary muscle and complete atrioventricular canal, repair may be accomplished by borrowing from the tricuspid portion of the anterior leaflet, rotating that part posteriorly, and partially closing the cleft. Small perforations of the mitral leaflet do not require closure and do not result in regurgitation. Echocardiographic and angiographic delineation of these abnormalities and thorough intraoperative exploration are important in avoiding pitfalls at the time of repair.

The role of the Glenn shunt in patients undergoing the Fontan operation

Twenty-seven patients (3 to 22 years) underwent the Fontan operation. Seventeen had tricuspid atresia and 10 had other complex lesions. Sixteen patients had a Glenn shunt (12 prior to, three simultaneous with, and one following the Fontan operation). One early death (3.7%) occurred in a 4 1/2-year-old child with tricuspid atresia II-C, previous pulmonary artery banding, and a closing ventricular septal defect (80 mm Hg gradient). There were two late deaths (7.4%) from Candida sepsis, after 4 and 6 months, respectively. The 24 patients who survived the Fontan operation had postoperative hospital stays of 6 to 90 days (average 18). Patients with tricuspid atresia and an established Glenn shunt (nine patients, Group I) had postoperative hospital stays of 7 to 19 days (average 9.5), and none had significant pleural or pericardial effusions. Patients with tricuspid atresia without a Glenn shunt (seven patients, Group II) had postoperative hospital stays of 6 to 60 days (average 17.5), with three having significant effusions. Of the patients with other complex lesions, all without an established Glenn shunt, five had significant effusions. Four additional major complications (two tricuspid patch disruptions with ineffective pulmonary blood flow and two complete occlusions of a valved conduit) were encountered in which the Glenn shunt proved lifesaving. We believe that an established Glenn shunt played a major role in attaining minimal postoperative hemodynamic instability, effusions, renal failure, and mortality in our patients. The Glenn shunt should be considered in patients who are less than ideal candidates for the Fontan operation.

Measurement of mitral valve orifice area in infants and children by two-dimensional echocardiography

Two-dimensional echocardiograms of the mitral valve orifice area were obtained in 50 normal pediatric subjects, 15 patients with congenital mitral stenosis and 7 patients with tricuspid atresia. The mitral area was measured near the tips of the mitral valve leaflets from a diastolic cross-sectional image of the left ventricle. The cardiac images were recorded on videotape and later transferred to video disc for high resolution contour tracing. Contour analysis was performed by a special purpose microcomputer system for calculation of the enclosed calibrated area. In normal patients, there was an excellent correlation (r = 0.95) between mitral valve area (MVA) (in cm2) and body surface area (BSA) (in m2) described by MVA = 4.83 X BSA - 0.07. Each patient with mitral stenosis had a mitral valve area that measured less than the third percentile predicted from the normal regression formula. In eight patients in whom the Gorlin formula could be applied, there was excellent correlation (r = 0.95) between echocardiographic and hemodynamic measurements of mitral valve area. Each patient with tricuspid atresia had a very large mitral valve area (greater than 99th percentile of normal). It is concluded that noninvasive measurement of mitral valve orifice area can be accurately achieved by two-dimensional echocardiography in pediatric patients with congenital mitral stenosis, allowing serial measurement of their mitral valve area.

Two-dimensional echocardiographic recognition of papillary muscle fibrosis in pediatric patients

Two-dimensional echocardiographic examinations were performed in seven infants with anomalous origin of the left coronary artery from the pulmonary artery (ALCA), in one infant with myocardial infarction and left main coronary obstruction, and in eight with critical valvar aortic stenosis (AS). Comparative qualitative echo density assessment demonstrated that each infant had a marked increase in the echo density of one or both left ventricular papillary muscles. The increased echo density was considered to represent fibrosis and scar formation as a result of ischemia and infarction. Pathologic proof of excessive fibrosis of the papillary muscles was obtained in three cases. In an additional case, calcification of the papillary muscle was noted on fluoroscopic examination. The echocardiographic appearance of papillary muscle fibrosis provides a useful indicator of severe subendocardial ischemia in patients with either critical AS or ALCA.

Two-dimensional echocardiographic features of interruption of the aortic arch

The 2-dimensional echocardiographic features of interruption of the aortic arch are presented based on analysis of the echocardiograms and angiograms from 8 infants: 2 with type A and 6 with type B interruption. Each infant had a patent ductus arteriosus, 6 had a conoventricular septal defect with leftward deviation of the conal septum, 1 had truncus arteriosus with truncal valve stenosis, and 1 had a distal aortopulmonary septal defect with an intact ventricular septum. Echocardiographic images obtained from the suprasternal notch or from a high parasternal approach demonstrated the interruption of the aortic arch and continuation of the patent ductus arteriosus into the descending aorta. These findings were compared with those in infants with aortic atresia and a hypoplastic ascending aorta or discrete coarctation of the aorta with tubular hypoplasia of the aortic arch. Types A and B interruption of the aortic arch were easily differentiated and the caliber of the patent ductus arteriosus was assessed. The characteristic conoventricular septal defect was readily visualized froma an apex 2-chamber view or from a subcostal sagittal plane view. With this information subsequent angiography can be more expeditiously performed in this group of critically ill infants.

Distal aortopulmonary septal defect, aortic origin of the right pulmonary artery, intact ventricular septum, patent ductus arteriosus and hypoplasia of the aortic isthmus: a newly recognized syndrome

The association of distal aortopulmonary septal defect, aortic origin of the right pulmonary artery, intact ventricular septum and interruption or coarctation of the aortic isthmus has not previously been reported as a syndrome. This combination of anomalies was encountered in five new patients and was previously reported in three. Two patients have undergone surgery with successful results. In contrast to the sagittally oriented conventional proximal aortopulmonary septal defect, the patients in this series had a more distal type of defect, possibly representing a partial persistence of the common arterial trunk. The pulmonary arterial bifurcation may malattach to this undivided truncal segment and, as a result, the right pulmonary artery may be partially or completely shifted into the aorta. This abnormal right pulmonary arterial origin may lead to "steal" from the aortic flow during embryogenesis and to hypoplasia of the aortic arch. This concept is supported by the angiographic observation that the greater the rightward displacement of the right pulmonary artery, the greater the hypoplasia of the arch. The diagnostic angiographic sign is a strikingly high origin of the right pulmonary artery together with aortic arch hypoplasia or atresia. Closure of the aortopulmonary septal defect with implantation of the right pulmonary artery in the pulmonary trunk and repair of the aortic arch anomaly is the recommended surgical treatment.