Howard S. Weber

Cardiac growth in fetuses of diabetic mothers with good metabolic control

To evaluate cardiac growth in fetuses of those diabetic mothers with good metabolic control, we examined M-mode echocardiographic measurements obtained from 24 fetuses of diabetic mothers (FODM) and compared these with measurements from 31 normal fetuses of similar gestational age. Fetuses were grouped into three gestational periods: 20 to 26 weeks, 27 to 33 weeks, and 34 to 40 weeks. The mothers were believed to have good metabolic control on the basis of mean daily glucose profiles and glycosylated hemoglobin A (HbA1C) values of approximately 110 mg/dl (610 mumol/L) and 7.5%, respectively, before fetal scanning, and estimated fetal weight similar to that of normal fetuses during all three gestational periods. Both FODM and normal fetuses had significant increases in M-mode measurements from period 1 to period 3, but in FODM, cardiac hypertrophy developed by late gestation (period 3). This involved the interventricular septum (6.1 +/- 0.7 vs 4.9 +/- 0.3 mm, p less than 0.05), right ventricular free wall (5.7 +/- 0.8 vs 3.2 +/- 0.3 mm, p less than 0.01), and left ventricular free wall (6.4 +/- 0.6 vs 3.3 +/- 0.4 mm p less than 0.01). The interventricular septum/right ventricular free wall ratio was similar, whereas the interventricular septum/left ventricular free wall ratio in FODM was smaller by period 3 (1.0 +/- 0.1 vs 1.6 +/- 0.1, p less than 0.05). The right ventricular diastolic dimension was similar, but the left ventricular diastolic dimension was significantly smaller in FODM during periods 2 and 3 (8.2 +/- 1.2 vs 12.2 +/- 0.7 mm, p less than 0.05). Strict metabolic control did not prevent FODM from having abnormal cardiac growth. We conclude that good metabolic control results in normal estimated fetal weight but that FODM remain at risk for mild global cardiac hypertrophy and altered diastolic dimensions.

The Norwood operation and subsequent Fontan operation in infants with complex congenital heart disease

From April 1987 to September 1993, 60 infants underwent a Norwood operation for complex congenital heart disease including hypoplastic left heart syndrome (n = 41), ventricular septal defect and subaortic stenosis with aortic arch interruption/severe coarctation (n = 7), complex single right ventricle with subaortic stenosis (n = 8), critical aortic stenosis with endocardial fibroelastosis (n = 2), and malaligned primum atrial septal defect with coarctation (n = 2). Age at operation ranged from 1 day to 3.9 months (mean 9 days, median 3.5 days). The operative mortality (< 30 days) was 33% (20 patients). Late mortality was 17% (10 patients). Nine of the 20 (45%) operative deaths occurred during the first 2 days after the operation as a result of sudden hemodynamic instability. All four infants with premature closure of the foramen ovale had pulmonary lymphangiectasia and died of pulmonary failure. Seven operative deaths have occurred in 36 patients since 1990 (19%); in the past 2 years, no operative deaths have occurred in 22 patients. Overall, there are 30 long-term survivors (50%). Twenty-one of these 30 infants have undergone a two-stage repair with a modified Fontan operation at 7.3 to 27.6 months of age (mean 18.1 months) with no mortality. Six patients have entered a three-stage repair strategy by undergoing a hemi-Fontan procedure at 6.8 to 23.0 months (mean 8.8 months) with no mortality, and two of these patients have now had their modified Fontan operation at 23.0 to 46.7 months of age with no mortality (four are still awaiting surgery). Two patients have undergone a two-ventricle repair with a Rastelli procedure, with no mortality at 7.4 and 14.1 months of age. Early in our experience, infants undergoing the Norwood operation had a high early mortality most often related to sudden hemodynamic instability. After we instituted a protocol that adds carbon dioxide to the inspired gas during postoperative mechanical ventilation, the postoperative course became more stable and there have been no operative deaths. In summary, the operative mortality for the Norwood operation continues to improve. A subsequent Fontan operation can be performed with excellent clinical results.

Balloon aortic valvotomy through a carotid cutdown in infants with severe aortic stenosis: Results of the multi-centric registry

OBJECTIVES The purpose of this study was to evaluate the short and intermediate term results of infants who have undergone balloon aortic valvotomy from the carotid arterial approach, and to identify risk factors in those infants who had a poor outcome. METHODS Between 1988 and 1999, balloon aortic valvotomy was attempted at four centres in 95 infants with severe aortic stenosis. Echocardiographic and hemodynamic data, and outcome, were analysed retrospectively. RESULTS Valvotomy was accomplished in 92 of the 95 infants, with a median age of 5 days, a range from 0 to 191 days, and weighing 3.4 kg, with a range from 1.0 to 6.5 kg. Major procedural complications occurred in 10 infants. Post-procedural aortic regurgitation was severe in 5 patients. There were 13 early deaths, and 4 late deaths. The period of mean follow-up has been 2.1 years, with a range from 0 to 9.3 years. The actuarial survival at 3 years was 76 +/- 6%. Further interventions were needed in 19 patients, giving a 3-year freedom from reintervention of 67 +/- 6%. The 51 infants who were duct-dependent were further analyzed, and found to have a higher mortality (38%) compared to those infants not dependent on the arterial duct (5%). Risk factors for a poor outcome in the duct-dependent infants were mitral stenosis (p<0.005), a left ventricle which did not form the cardiac apex (p<0.005), and an aortic valve with a diameter of less than 6 mm (p<0.05). CONCLUSIONS This multi-centric registry shows good results in the intermediate term for treating infants with severe aortic valvar stenosis with balloon valvotomy through a carotid arterial cutdown. Infants dependent on prostaglandin had a worse outcome, especially if they had any of the identified risk factors.

Transcarotid Balloon Valvuloplasty with Continuous Transesophageal Echocardiographic Guidance for Neonatal Critical Aortic Valve Stenosis: An Alternative to Surgical Palliation

Abstract. Neonatal critical aortic valve stenosis is a life-threatening malformation if untreated. Before the late 1980s, the preferred treatment was surgical valvotomy; however, operative mortality was high. Early reports of transcatheter balloon dilation were encouraging, although femoral artery damage and aortic valve insufficiency were procedural limitations. With new balloon catheter technology, transumbilical, transvenous, and transcarotid approaches have been advocated, although a comparison with recent surgical results has not been performed. We compared all neonates who presented to our institution since 1985 with the diagnosis of critical aortic stenosis. Ten patients underwent surgical transventricular valvotomy and 13 patients underwent balloon valvuloplasty via a right carotid cutdown with continuous transesophageal echocardiographic guidance. Prior to intervention, all patients had either left ventricular dysfunction, an aortic valve gradient >100 mmHg, significant mitral valve insufficiency, and/or ductal dependent systemic blood flow. All patients had successful relief of aortic valve obstruction with normalization of left ventricular function and successful discontinuation of prostaglandin E1. Use of continuous transesophageal echocardiographic guidance resulted in fluoroscopic exposure of only 12 ± 8 minutes. At the latest follow-up, a similar proportion of patients has required additional aortic valve procedures (38% vs 25%) and overall mortality (20% vs 15%) is similar. In the transcarotid group, 9 of 13 patients (69%) have a normal appearing right carotid artery by Duplex imaging, and no neurologic events have been reported. Balloon aortic valvuloplasty via a right transcarotid approach is safe, simplifies crossing the valve, and is effective for the initial palliation of neonatal critical aortic stenosis. The use of transesophageal echocardiographic guidance reduces fluoroscopy exposure, enables accurate assessment of hemodynamics without catheter manipulation or angiography, and avoids femoral artery injury.

A reconsideration of risk factors for the Fontan operation.

We reviewed our experience in 38 patients who underwent a Fontan operation. In the first five patients ages 7.5 to 23 years (mean, 15 years), a conduit was placed from the right atrium to the small right ventricle or the pulmonary artery (PA). The remaining 33 patients, ages 7 months to 14 years (mean, 4.8 years), had a modified Fontan operation with direct systemic venous or right atrial to PA anastomosis. The diagnoses were tricuspid atresia (n = 14), single ventricle (n = 10), hypoplastic right or left ventricle (n = 9), double-outlet right ventricle with inlet ventricular septal defect and pulmonary atresia or stenosis (n = 3), criss-cross ventricles and transposition of the great arteries (n = 1), and atrioventricular canal and anomalous pulmonary venous connection (n = 1). Thirty-two patients had previous surgery. Other procedures included PA banding (n = 7), systemic to PA shunts (n = 25), Norwood operation (n = 3), and a Damus-Kaye-Stansel anastomosis (n = 1), repair of total anomolous pulmonary venous connection (n = 1), a Blalock-Hanlon atrial septectomy (n = 1), and enlargement of a restrictive ventricular septal defect (n = 1). There were four operative deaths (10.5%), three from low cardiac output and one from subaortic obstruction. There were no deaths in patients younger than 3 years of age (n = 13). Subaortic obstruction developed in six of the seven patients who had pulmonary artery banding and resulted in three deaths. In our experience, diagnosis, previous surgery, type of previous operation, PA pressure, and younger age are not risk factors for early or late death. Subaortic obstruction is a major risk factor for late death. Accordingly we now perform a Damus-Kaye-Stansel anastomosis combined with a systemic to PA shunt in those children with excessive pulmonary blood flow who anatomically are likely to develop subaortic obstruction. A modified Fontan operation can be performed any time after 1 year of age and in some patients after 6 months of age, providing the anatomy and physiology of the patient are acceptable.

Incidence and predictors for the development of significant supradiaphragmatic decompressing venous collateral channels following creation of Fontan physiology

The occurrence of supradiaphragmatic decompressing venous collateral channels following construction of a bidirectional cavopulmonary connection or completion of the Fontan operation resulting in abnormal systemic hypoxemia has been infrequently described. In addition, the incidence and predictors of these channels have not been well delineated, especially in those patients without formation of such structures preoperatively. I evaluated, retrospectively, 40 patients who had undergone either construction of a bidirectional cavopulmonary shunt or completion of the Fontan operation, and who had complete pre and postoperative hemodynamic and angiographic data. Of the patients, 17 (43%) had developed a total of 21 decompressing venous collateral channels, of which 7 (18%) were considered to be hemodynamically significant requiring transcatheter coil occlusion. Of all variables examined, seven patients with significant decompressing collaterals had a greater transpulmonary gradient at follow-up catheterization (8 +/- 2 vs 5 +/- 2 mmHg, p=.01) and lower systemic saturations at routine clinical follow-up visits (82 +/- 5 vs 89 +/- 5 mmHg, p =.007) in comparison to the 33 others. When not evident preoperatively, decompressing venous collateral channels develop in a significant number of patients following conversion to Fontan physiology. If sufficiently large, they may produce lower than expected systemic saturations for the observed cardiac physiology. The larger decompressing channels are more likely to occur when a greater transpulmonary gradient exists postoperatively, which may require cardiac catheterization and transcatheter coil occlusion.

Role of balloon atrial septostomy before early arterial switch repair of transposition of the great arteries.

Preoperative balloon atrial septostomy is the standard therapy for babies with uncomplicated cyanotic dextrotransposition of the great arteries despite the effectiveness of prostaglandin E1 infusion in alleviating systemic hypoxemia and the reported success of arterial switch repair during the 1st weeks after birth. The clinical records and echocardiographic findings of 23 infants (mean birth weight +/- SD 3.3 +/- 0.5 kg) with uncomplicated transposition of the great arteries were analyzed. Fifteen infants (Group I) did not undergo septostomy, and 8 (Group II) underwent septostomy. Before prostaglandin infusion, mean arterial oxygen tension (Po2) in Group I (26 mm Hg) did not differ from that in Group II. After prostaglandin infusion, Po2 increased significantly in Group I (43 +/- 8 mm Hg, p less than 0.001) but not in Group II despite a widely patent ductus and predominant left to right ductal shunt in all. After septostomy, Po2 increased significantly (43 +/- 4 mm Hg, p less than 0.03), and did not differ from that in Group I. Echocardiographic features generally demonstrated a nonrestrictive foramen ovale in Group I and a restrictive foramen ovale in Group II. The latter was associated with persistent hypoxemia after prostaglandin. Thus, the diameter of the foramen ovale was the primary factor influencing arterial oxygenation during prostaglandin infusion. Babies underwent the arterial switch operation at a mean age of 70 +/- 65 h with an overall survival rate of 96%; there was only one postoperative death (Group II). Absence of septostomy had no negative influence on any postoperative variable, including duration of ventilatory and inotropic support, time to discharge, or mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary artery growth fails to match the increase in body surface area after the Fontan operation

Objective: To evaluate the growth of the pulmonary arteries after a Fontan procedure. Design: Retrospective review. Setting: Two paediatric cardiology tertiary care centres. Patients: 61 children who underwent a modified Fontan operation and had angiography suitable for assessment of pulmonary artery size before the Fontan procedure and during long term follow up. An atriopulmonary connection (APC) was present in 23 patients (37.7%) and a total cavopulmonary connection (TCPC) was present in 38 (62.3%). Postoperative angiograms were performed 0.5–121 months (median 19 months) after the Fontan operation. Main outcome measure: Growth of each pulmonary artery measured just before the first branching point. The diameter was expressed as a z score with established nomograms used to standardise for body surface area. Results: The mean change in the preoperative to postoperative z scores of the right pulmonary artery was −1.06 (p  =  0.004). The mean change in the preoperative to postoperative z scores of the left pulmonary artery was −0.88 (p  =  0.003). Changes in the preoperative to postoperative z scores were more pronounced in the patients undergoing APC than TCPC, especially for the right pulmonary artery. Conclusion: After the Fontan operation, growth of the pulmonary arteries often fails to match the increase in body surface area.

The Fontan operation in infants less than 2 years of age

Young age remains a reported risk factor for a successful Fontan operation despite improved survival rates. Since March 1978, the Fontan operation has been performed in 47 patients. To avoid a primary or secondary palliative shunt, an early Fontan procedure (Group 1: mean age 1.5 +/- 0.5 years, range 0.6 to 2) has been performed in 17 children with the outcome similar to that of the remaining 30 older patients (Group 2: mean age 7.5 +/- 5 years, range 2.4 to 23 years). Preoperatively both groups had acceptable hemodynamic status for a successful Fontan result. Operative variables including cardiopulmonary bypass time, aortic cross-clamp time and core temperature were similar between groups and did not affect mortality. The postoperative mortality rate including early surgical (0% vs. 13%, respectively), late (18% vs. 12%) and total (18% vs. 23%) was similar between Groups 1 and 2 (p greater than 0.05). Immediate postoperative arrhythmias were more frequent in Group 1 (71% vs. 25%, p less than 0.01) with no related mortality, while late arrhythmias occurred with equal frequency (29% vs. 39%, p greater than 0.05). Group 1 infants required a longer hospital stay (22 +/- 9 vs. 14 +/- 5 days, p less than 0.01). Thus, young age is not a risk factor for successful outcome of the Fontan operation in patients with acceptable preoperative hemodynamic status. An early Fontan operation may also avoid prolonged palliative procedures and their potential deleterious effects.

Initial and late results after catheter intervention for neonatal critical pulmonary valve stenosis and atresia with intact ventricular septum: a technique in continual evolution.

Critical pulmonary valve stenosis or atresia with intact ventricular septum is a rare congenital cardiac defect that can be technically difficult to alleviate in the catheterization laboratory. Over the past 10 years, several techniques and modifications with variable results have been advocated to facilitate the valvuloplasty procedure. This report describes a single operators experience using various techniques in 28 neonates with critical pulmonary stenosis or atresia who were considered candidates for transcatheter intervention. The first two patients underwent a gradational balloon valvuloplasty approach that resulted in prolonged fluoroscopy exposure. Thereafter, a “snare assisted” umbilical artery approach was developed which facilitated the valvuloplasty procedure and resulted in significantly fewer balloons used and shorter fluoroscopy times. Early in our experience, stiff guidewire perforation of atretic pulmonary valves was used, whereas in our last two patients, a simplified perforation technique with a new 0.9‐mm excimer laser catheter was used. Late echocardiographic and clinical follow‐up evaluation in 27 patients demonstrates persistent gradient relief, resolution of tricuspid valve insufficiency, and elimination of right to left shunting at the atrial level. Balloon valvuloplasty is the treatment of choice for critical pulmonary valve stenosis or atresia with intact ventricular septum. When necessary, the use of umbilical artery “snare assistance” facilitates the valvuloplasty technique and shortens procedure time while laser perforation is currently preferable for perforation of the atretic pulmonary valve. Cathet Cardiovasc Intervent 2002;56:394–399.