Michael A. LaCorte

Noninvasive Pulse Oximetry In Children With Cyanotic Congenital Heart Disease

Arterial oxygen saturation, determined noninvasively by pulse oximetry in 32 pediatric patients with cyanotic congenital heart disease (CHD), was compared with oxygen saturation measured by a cooximeter in simultaneously obtained arterial blood samples. The patients were studied in the cardiac catheterization laboratory, operating room, and ICU. Excellent correlation by linear regression (n = 108, r = .95) was observed between the two methods at oxygen saturations ranging from 35% to 95%. These observations show that in infants and children with cyanotic CHD, arterial oxygen saturations can be determined accurately and reliably by pulse oximetry at rest and during changing circulatory states.

Cardiac magnetic resonance imaging in children with congenital heart disease.

Electrocardiogram-gated magnetic resonance imaging (MRI) was used to evaluate 36 children, ages 2 to 17 years, with congenital heart disease. With the use of multiple imaging planes, including transverse, sagittal, coronal, and 60-degree left anterior oblique views, high contrast images with excellent spatial resolution were produced. In 34 of the 36 patients the anatomic detail provided by MRI was sufficient to make the cardiac diagnosis. Electrocardiogram-gated MRI is an important new imaging technique for use in children with cardiovascular disease.

Cardiac MR imaging in Pompe disease.

The magnetic resonance (MR) imaging findings in a 5-month-old infant with glycogen storage disease of the heart revealed hypertrophy of the right and left ventricles and the interventricular septum with an irregular inhomogeneous appearance of the myocardium. The descriptive features of the MR study are correlated with cardiac angiography and echocardiography in Pompe disease.

Experience with Congenital Heart Disease in Children from Developing Countries

The natural history of cyanotic congenital heart disease was described in the 1940s and 1950s from experiences in the United States and other developed nations. [1–3]. Since the advent of palliative procedures (including balloon septostomy), palliative surgery, and corrective surgery, the natural history of cyanotic congenital heart disease has been greatly altered. However, in developing countries around the world, individuals with congenital heart disease still do not receive the benefits of modern therapeutic modalities. In 1980, a program called Lifeline was instituted at North Shore University Hospital, Manhasset, New York. This program was designed to provide care for children with heart disease living in developing countries.

169 NON-INVASIVE DETERMINATION OF ARTERIAL OXYGEN SATURATION IN CYANOTIC CONGENITAL HEART DISEASE

We evaluated non-invasive transcutaneous pulse oximetry (NIPO) in 28 pediatric pts, ages 3 mos.-11 yrs, wts. 2.5-36 kgs. with moderate to severe cyanotic congenital heart disease (CyCHD) during cardiac catheterization, intra-operatively during closed heart surgery and in the ICU. O2 saturations (sats) from (NIPO), using the Nellcor Pulse Oximeter #100, were compared with simultaneously obtained arterial blood samples analyzed by the IL282 CO-oximeter. Comparison of 94 data pairs showed excellent agreement between the 2 methods over a wide range of O2 sats (38-90%) with r=.93 SEE 3.62. Even in the low range of O2 sats (38-75%) 34 data pairs showed good agreement between the 2 methods, r=.81 SEE 5.14. The accuracy of the NIPO was independent of the pts wt., heart rate or blood pressure. In 3 pts, the sharp decrease in O2 sats allowed the diagnosis of hypoxic tetralogy spells before the onset of any clinical findings. Intra-operatively the use of NIPO confirmed the patency of aorto-pulmonary shunts and changes in arterial O2 sats accompanying general anesthesia. Post operatively in the ICU, NIPO allowed accurate management of ventilatory support during varying hemodynamic states. Thus, in children with CyCHD, NIPO is an accurate method of determining O2 sats and contributes to improved management during cardiac catheterization, heart surgery and recovery in the ICU. This study establishes a new application of NIPO in the care of children with CyCHD.

114 MAGNETIC RESONANCE IMAGING IN CHILDREN WITH CONGENITAL HEART DISEASE

Electrocardiographic (ECG)-gated magnetic resonance imaging (MRI) studies were done on 23 children ages 1-17 yrs. with a 0.6 Telsa super-conducting magnet using coronal, transverse, sagittal and left anterior oblique planes. A spin echo pulsing sequence with a 30 msec time to echo delay was used. Two dimensional sections 0.75cm-1.0cm thick were obtained with an average scanning time of 4 min per viewing plane. Diagnoses included: tetralogy of Fallot (10), atrial septal defect (5), ventricular septal defect (3), single atrium (1), transposition of great arteries (1), subaortic stenosis (1), Intracardiac tumor (2). All diagnoses were confirmed by cardiac catheterization and/or echocardiography. MRI studies gave precise, diagnostic visualization of cardiac malformations in 21/23 cases. The transverse view afforded excellent visualization of ventricular and atrial septal defects, main pulmonary artery and its branches. The coronal view demonstrated the aortic arch, right ventricular outflow and inflow tracts. The sagittal view delineated aortic arch and right ventricular outflow tract anatomy. The left anterior oblique view localized ventricular septal defects, aortic arch abnormalities and demonstrated aortic override in tetralogy of Fallot. In cardiac tumors, the size, location and extent of myo-cardial attachment was well delineated by MRI. In summary, MRI is a safe, accurate, non-invasive test which gives detailed information of cardiac anatomy in congenital heart disease.

83 MAGNETIC RESONANCE IMAGING STUDIES IN COARCTATION OF THE AORTA AND THE MARFAN SYNDROME

ECG-gated magnetic resonance imaging (MRI) studies were done on 8 children with coarctation (coarc) of the aorta (Ao), 2-17 yrs., and 8 patients (pts) with Marfan Syndrome (MF), 10-27 yrs. Multiple imaging planes were obtained using a 0.6T super-conducting magnet, and 0.75-1cm thick sections. In the coarc pts, 1 had MRI pre and post surgery, 1 had MRI pre and post balloon angioplasty (BA), 5 had MRI post BA and 1 had MRI pre BA. Precise visualization of the coarc was noted in the 2 pre therapy studies and in the BA pt the MRI coarc diameter correlated with the angiographic diameter. After therapy there was documentation of relief of the coarc on MRI; no aneuryms were seen in the BA pts. In MF, the Ao root, ascending Ao (Asc Ao), Ao arch and descending Ao (Desc Ao) were well delineated. All MF pts had dilation of the Ao root and Asc Ao: none had dilation of the Desc Ao. In both coarc and MF, the sagittal view gave best visualization of the Ao isthmus, Desc Ao and collaterals when present. Asc Ao and arch vessels were best seen on the left anterior oblique and coronal views. Thus, MRI gives excellent visualization of the Asc Ao, Ao arch, and Desc Ao comparable only to invasive angiography. In coarc, MRI allows accurate localization of site of coarc, and non-invasive follow up of treatment. In MF, MRI provides an excellent means of serial evaluation of the aorta.

142 ELECTROPHYSIOLOGIC EVALUATION OF TETRALOGY OF FALLOT TOF REPAIR: EARLY POSTOPERATIVE STUDIES

Cardiac arrhythmias are common after repair of TOF and are associated with sudden death. We performed 9 electrophysiologic studies in 5 patients (pt.), ages 6-16 yrs. with TOF 1-26 days after repair to identify pt. at risk for arrhythmias. Rapid atrial pacing and programmed atrial and ventricular stimulation were carried out using intracardiac catheters (2 pt.-2 studies) or epicardial pacing wires placed intraoperatively on the right atrium, right ventricular apex (RVA) and outflow tract (RVOT, 5 pt.-7 studies). Epicardial pacing studies were performed at the bedside or in the intensive care unit (ICU). Junctional rhythm was present at the first study in 2 pt. Wenckenbach periodicity occurred at an average cycle length of 236 + 88 Msec. Dual pathway atrio-ventricular conduction, anterograde and retrograde, was observed in 1 pt. Atrial flutter was induced in 1 pt. Ventricular effective (VERP) and functional (VFRP) refractory periods (RP) determined at the RVA (VERP 193.8 ± 19.3, VFRP 212.5 ± 19.8 mesc) and RVOT (VERP 197.5 ± 19.2, VFRP 215.3 ± 19.3 msec) were similar. The ventricular RP determined by intracardiac or epicardial stimulation were identical. Repetitive ventricular responses were observed in 1 pt. Single (S1, S2) or double (S1, S2, S3) extrastimuli failed to induce ventricular arrhythmia. These observations suggest that electrophysiologic studies can be safely carried out in the immediate post operative period at the bedside or in the ICU and may be helpful in identifying pt. at risk of developing cardiac arrhythmia.