Use of single lead VDD pacing in children.

The development of transvenous ventricular pacing leads with proximal electrodes capable of atrial sensing and the recent availability of smaller generators has created the opportunity to treat children with complete AV block and normal sinus node function with a transvenous single lead VDD pacing system. Studies in adults have demonstrated this system to be efficacious with low complication rates. Transvenous single lead VDD pacemakers were implanted in ten children, aged 5-15 years, between December 1993 and April 1996, in our institution. The indications were complete AV block with severe bradycardia in 5 patients, second-degree or complete AV block following congenital heart surgery in 3, complete AV block with long QT syndrome in 1, and second-degree AV block and syncope in 1. There were no complications related to the procedure in any case. P and R wave amplitudes were measured and thresholds were determined intraoperatively on all patients. Amplitudes and thresholds were remeasured on seven patients with a mean follow-up of 17 months; Holter monitors were performed on seven patients with mean follow-up of 16 months. P and R wave amplitudes were generally diminished at follow-up compared to initial values but remained within an acceptable range for all patients. Four patients required reprogramming after pacemaker insertion, 1 received an atrial lead for dual chamber pacing, 1 required reposition for lead dislodgment, and 1 patient required a new lead for an inadequate ventricular pacing threshold. No patient had evidence of failure to sense or capture as evaluated by Holter monitoring at last follow-up. Single lead VDD pacing systems can be successfully used in properly selected children with high degree or complete AV block with normal sinus node function.

Transcatheter coil occlusion of surgical fenestration after Fontan operation.

BACKGROUND: Fenestration of the Fontan circulation that results in a residual right-to-left shunt has improved operative survival rates among high-risk patients. Late closure of the fenestration by use of a transcatheter umbrella device has achieved separation of the systemic and pulmonary venous circulations, "completing" the Fontan pathway. Because use of umbrella devices is restricted, many institutions continue to perform only nonfenestrated Fontan procedures. METHODS AND RESULTS: Five children 3.5 to 8.3 years old (mean, 5.1 years) underwent cardiac catheterization 0.5 to 24 months (mean, 10 months) after operation for the purpose of occluding a persistently patent Fontan fenestration. Once candidacy was determined, an 8-mm x 10-cm Gianturco coil was delivered to straddle the fenestration with established techniques for coil occlusion of patent ductus arteriosus. Complete occlusion occurred in 4 of 5 patients, in 2 of the 4 before they left the catheterization laboratory. One patient had a residual angiographic shunt but had complete closure within 24 hours by echocardiography. In 1 patient who had a residual shunt at 24 hours, the fenestration was completely closed at 1 month after coil placement. One patient had residual shunting at 2 months but saturations have increased 15% to 17% since coil placement. No embolizations (early or late), clinical hemolysis, thromboembolic events, or hemodynamic deterioration occurred among patients during 1- to 14-month follow-up periods. CONCLUSIONS: A persistently patent fenestration after Fontan operation may be closed with a Gianturco coil. This universally available alternative to umbrella devices may make the fenestrated Fontan a more appealing option to centers that had not previously considered its use.

Initial experience with percutaneous transhepatic cardiac catheterization in infants and children.

Percutaneous transhepatic cardiac catheterization is a straightforward procedure that can be performed by experienced pediatric interventionalists with little additional training. We believe that this technique can be a valuable tool in the treatment of selected patients with complex congenital heart defects.

Malignant wide complex tachycardia after adenosine administration to a postoperative pediatric patient with congenital heart disease.

Adenosine has become the treatment of choice for paroxysmal supraventricular tachycardia because of its safety and efficacy. There have been no reports of malignant arrhythmias occurring after adenosine administration. This case report presents the occurrence of a malignant wide complex tachycardia after intravenous adenosine administration in a 10-year-old boy 2 days after a Fontan procedure. Thus the administration of adenosine in a critically ill postoperative patient can have morbidity or potential mortality and must be monitored closely.

Usefulness of intermittent monitoring of mixed venous oxygen saturation after stage I palliation for hypoplastic left heart syndrome.

Most deaths after stage I palliation for hypoplastic left heart syndrome have occurred within the first 24 hours after surgery. Efforts to improve 1-day survival should therefore have significant impact on improving overall survival. Early death has most often been attributed to low cardiac output and abnormalities of pulmonary to systemic flow ratio (Qp/Qs). Thirteen infants underwent stage I palliation and had a catheter inserted in the high superior vena cava (SVC) for intermittent measurement of SVC oxygen saturation. Calculation of Qp/Qs was achieved using SVC saturation as a mixed venous oxygen saturation, and estimating pulmonary venous oxygen saturation. Eleven patients survived, and 2 patients died within the first 24 hours. Abnormalities in Qp/Qs were noted in 12 of 13 patients after operation. In 10 of these 12 patients, there was a high Qp/Qs, which has been associated with poor outcome. High Qp/Qs was noted even in patients with acceptable arterial oxygen saturations (< 85%). SVC saturation increased in all survivors during the first 24 hours, and was associated with a decrease in Qp/Qs. Measurement of SVC oxygen saturation appears to be a valuable adjuvant in the postoperative management of infants after stage I palliation of hypoplastic left heart syndrome. Major abnormalities in Qp/Qs can be detected even with acceptable arterial saturations. With this information, early ventilator/pharmaceutical adjustments can be made which may improve stage I survival.

Use of adenosine in the management of perioperative arrhythmias in the pediatric cardiac intensive care unit.

OBJECTIVE: To assess the safety, efficacy, and diagnostic usefulness of iv adenosine in treating acute episodes of paroxysmal supraventricular tachycardia in critically ill infants and children with congenital heart disease. DESIGN: A consecutive sample study over a 1-yr period. SETTING: A six-bed pediatric cardiac ICU at a tertiary care center. PATIENTS: Nine consecutive critically ill infants and children with congenital heart disease, either awaiting emergent surgery or in the immediate postoperative period, who had at least one episode of tachyarrhythmia treated with iv adenosine. INTERVENTIONS: In children less than 50 kg, adenosine was administered in incremental doses of 100, 200, and 300 micrograms/kg every 3 mins. Patients weighing greater than 50 kg were given doses of 6, 12, and 18 mg iv. The adenosine protocol was stopped when the arrhythmia was terminated or a mechanism of the arrhythmia was shown that would not respond to adenosine administration. MEASUREMENTS AND MAIN RESULTS: Adenosine was used 14 times in nine patients, all of whom were hemodynamically unstable before or after the development of the tachyarrhythmia. Adenosine was effective in rapidly terminating all nine episodes of paroxysmal supraventricular tachycardia, six of which occurred in patients known to have Wolff-Parkinson-White syndrome. All patients had marked hemodynamic improvement after conversion to normal sinus rhythm. In five episodes of tachyarrhythmia that did not respond to adenosine, the transient block at the atrioventricular (A-V) node helped determine the underlying arrhythmia without clinically important side-effects. CONCLUSIONS: Adenosine can be used safely and effectively in critically ill infants and children with congenital heart disease and perioperative tachyarrhythmia. More investigation into the "chemical conversion" of paroxysmal supraventricular tachycardias as well as its diagnostic value in this subset of critically ill patients is warranted.

Intracardiac shunting in children with ventricular septal defect: evaluation with Doppler color flow mapping.

In children with a ventricular septal defect, transseptal blood flow has been demonstrated angiographically to be bidirectional in all but the smallest defects. To investigate this phenomenon noninvasively, two-dimensional Doppler color flow echocardiography was used in 77 patients (aged 1 day to 15.5 years, mean 24 months). During isovolumetric contraction, flow was seen from the left to the right ventricle in 82 (98%) of 84 studies. During isovolumetric relaxation, right to left flow was noted in 72 (96%) of 75 studies. During early diastole in patients with an isolated defect, flow was initially from the right to the left ventricle and subsequently reversed to become left to right in 29 (91%) of 32 studies. In patients with concomitant right ventricular volume overload, flow across the ventricular defect was from the right to the left ventricle throughout diastole in 30 (86%) of 35 studies. In each of four patients with d-transposition of the great vessels and each of two patients with 1-transposition of the great vessels, blood flow was from the morphologic left ventricle to the morphologic right ventricle during isovolumetric contraction and from the morphologic right ventricle to the morphologic left ventricle during isovolumetric relaxation. These results demonstrate 1) the complex nature of intracardiac shunting in children with ventricular septal defect as previously shown by angiography; 2) an intrinsic functional difference in the contractile and relaxation properties of the morphologic left and right ventricles; and 3) differences in diastolic blood flow patterns between children with an isolated defect and those with a ventricular septal defect and right ventricular volume overload (p = 0.0001).

Balloon angioplasty for aortic recoarctation: results of Valvuloplasty and Angioplasty of Congenital Anomalies Registry.

Balloon angioplasty was performed in 200 patients with recoarctation of the aorta in a multicenter prospective study. The average age at the time of the procedure was 7.0 years (range 1 month to 26 years). Systolic pressure (mean +/- standard deviation) in the ascending aorta decreased from 134.5 +/- 23.4 to 127.4 +/- 22.0 mm Hg. The descending aortic systolic pressure rose from 92.7 +/- 18.2 to 114.1 +/- 21.6 mm Hg. Peak systolic pressure differences decreased from 41.9 +/- 19.6 to 13.3 +/- 12.1 mm Hg. The diameter of the recurrent coarctation site increased from 5.2 +/- 2.9 to 8.9 +/- 3.4 mm. After angioplasty residual pressure differences of less than or equal to 20 mm Hg were found in 79.4% of the patients. Five patients died of complications related to the procedure (2.5%). Two deaths were directly related to the technical aspects of the procedure and 3 patients died because of the severity of the underlying disease. One additional patient had a cerebrovascular accident. Femoral artery complications occurred in 17 patients (8.5%) and 8 patients required surgical thrombectomy. Balloon angioplasty offers a satisfactory alternative to surgery for recurrent coarctation; both results and complications compare favorably with surgical therapy.

Magnetic resonance imaging of isolated abdominal aortic dissection.

In the absence of trauma or descending thoracic aortic dissection, abdominal aortic dissection is rare. This report presents a case of "isolated" abdominal aortic dissection. Magnetic resonance imaging may reliably diagnose and characterize these dissections without the use of contrast material.

Angioplasty for coarctation of the aorta: long-term results.

Balloon coarctation angioplasty (BCA) was performed in seven consecutive patients (five boys and two girls) 18 months to 18 years old (mean 9.5) with isolated discrete unoperated coarctation of the aorta. A No. 8F or 9F catheter was chosen with balloon lengths of 30 or 40 mm and maximum inflation diameters 1 mm less than the smallest measured aortic diameter determined 1 cm proximal to the coarctation site. A 10 sec inflation-deflation cycle of 6 to 8 atmospheres (90 to 120 psi) was performed. The peak systolic pressure gradient (PSG) before BCA ranged from 35 to 70 mm Hg (mean 58), and immediately after BCA it decreased to 0 to 20 mm Hg (mean 7). One to two year follow-up (mean 14 months) of the seven patients revealed a PSG range of 10 to 30 mm Hg (mean 19). Repeat angiography was performed immediately proximal to the coarctation site. Three patients (43%) had evidence of aneurysm formation at or immediately distal to the balloon dilatation site. One patient had coarctation restenosis. While initial results with BCA for unoperated coarctation were encouraging, current data raise serious concerns about its long-term safety and efficacy.

Balloon dilatation angioplasty: nonsurgical management of coarctation of the aorta.

Balloon dilatation angioplasty was successfully performed in five patients (ages 18 months to 17 years) with discrete aortic coarctation. The catheter size was No. 8F or 9F. Selection of balloon diameter was based on angiographic measurements of the aorta determined proximal and distal to the coarctation site. A 10 sec inflation-deflation cycle at 6 to 8 atmospheres (90 to 120 psi) was performed. The systolic pressure gradients across the coarctation before balloon dilatation angioplasty ranged from 35 to 70 mm Hg. Systolic pressure gradients after balloon dilatation angioplasty ranged from 0 to 10 mm Hg. All patients had normalized blood pressure immediately. Abnormal pulsed Doppler echocardiograms were observed in all patients before balloon dilatation angioplasty; four patients had normal echocardiograms after balloon dilatation angioplasty. No serious intraprocedural complications occurred. One patient required femoral artery thrombectomy 36 hr after balloon dilatation angioplasty. One to 6 months after balloon dilatation angioplasty no patients have evidence of restenosis of coarctation. Early results suggest that balloon dilatation angioplasty may offer a safe and effective nonsurgical alternative for the treatment of discrete coarctation in older infants and children. Long-term follow-up for the incidence of restenosis and formation of aneurysms will ultimately determine the efficacy and safety of this procedure.

Atrioventricular canal ventricular septal defect with cleft mitral valve. Angiographic and echocardiographic features.

A rare form of endocardial cushion defect is an atrioventricular (AV) canal-type ventricular septal defect with cleft mitral valve in the absence of a primum atrial septal defect. In two infants with Down's syndrome, preoperative delineation of this entity was accomplished. M-mode echocardiographic features included presence of two distinct AV valves, attachment of the anterior portion of the anterior leaflet of the mitral valve to the interventricular septum, and normal septal motion. Two-dimensional echocardiography demonstrated the intact atrial septum, ventricular septal defect, presence of two distinct AV valves, and the cleft mitral valve. Angled (axial) cineangiography was employed to delineate the AV valve morphological characteristics, position of ventricular septal defect, and absence of a primum atrial septal defect. Since the surgical approach to this lesion is different from other forms of endocardial cushion defects and specific problems related to AV valve morphology may be encountered, the preoperative diagnosis of this entity is important.