Thomas A. Vargo

Hemodynamic effects of dobutamine in children

Dobutamine is useful for augmenting cardiovasuclar function in adults. However, no information is available on the action of dobutamine in children. To determine its hemodynamic effects in children, we infused dobutamine into 12 children with congenital heart disease during diagnostic cardiac catheterization. We administered dobutamine in two doses: first 2 and then 7.75 microgram/kg per min for 10 minutes each. We meaured heart rate, cardiac output, systemic and pulmonary arterial, right atrial and pulmonary capillary blood pressures before and during the infusion of dobutamine. Systemic and pulmonary vascular resistances, cardiac index and stroke index were calculated. Cardiac output, cardiac index, stroke volume, stroke index and systemic arterial phasic and mean blood pressures increased sugnificantly (P less than 0.05) and pulmonary capillary mean blood pressure decreased significantly (P less than 0.05) during the infusion of each dose of dobutamine compared with control values. Heart rate, pulmonary and right atrial mean blood pressure and systemic and pulmonary vascular resistance were unchanged with either dose of dobutamine. We noted no adverse effect from the drug.

Percutaneous sheath cardiac catheterization

Abstract The feasibility and safety of percutaneous venous and arterial catheterization in infants and children was investigated prospectively from July 1, 1970 to July 1, 1971. Femoral vessel catheterization using an indwelling sheath was performed in 565 of 582 consecutive procedures attempted. The percutaneous technique was unsuccessful and a venous cutdown procedure required in 17 patients, a failure rate of 3 percent. Prior percutaneous procedures had been performed in 71 patients and, in most instances, the same vessels were used for the repeat catheterizations. Percutaneous retrograde arterial catheterization was attempted and accomplished in 260 patients. Left heart catheterization was achieved by passage of the venous catheter through a foramen ovale, atrial septal defect or ventricular septal defect in 229 of the 565 percutaneous venous prograde studies. A diminished arterial pulse was noted immediately after the procedure in 16 of the 260 patients who underwent retrograde arterial catheterization. Twelve of these 16 patients weighed less than 15 kg. The pulse remained diminished in only 3 of these 16 patients 3 to 6 months later. Advantages of percutaneous sheath cardiac catheterization include the ability to use the same vessel for repeat studies, the small incidence of arterial complications, the ease of making many changes in catheter as well as the ability to use any type of catheter. In addition, there is a greater chance of entering the left side of the heart with a prograde femoral venous catheter which, in many patients, may avoid performance of a retrograde arterial procedure.

Late development of pulmonary venous obstruction following Mustard's operation using a dacron baffle.

Tbree patients developed late pulmonary vein obstruction (PVO) following Mustards operation for transposition of the great arteries. In all three the absence of PVO bad been documented by an earlier postoperative cardiac catheterization. At reoperation shrinkage and kinking of the dacron baffle was evident. After Mustards operation, patients should be observed cloey for symptoms and signs of PVO since it can occur insidiously despite previously proven absence of this complication.

Intracardiac electrography in children and young adults

The interpretation of IE recorded in children has been hampered by a lack of agreement regarding normal values. We recorded IE in 158 children and young adults (ages, three days to 33 years) to define the various conduction intervals in normal and disease states. The HBP was recorded in 156 subjects. In 85 subjects with normal conduction indicated by surface ECG, including 19 subjects with normal hearts, there were no statistically significant age-related differences in internodal, A-V nodal, or His-Purkinje conduction intervals. Therapeutic levels of digitalis did not alter the conduction intervals. In 11 subjects with first degree A-V block and in five subjects with congenital complete A-V block, the site of block as determined by IE could not be predicted from the surface ECG. No abnormalities in conduction intervals were found in 18 subjects with right bundle branch block (surgically induced in 17 cases). Intracardiac electrography with recording of the HBP was found to be a safe, informative technique for electrophysiologic investigations in children and young adults.

The Use of Exercise Testing in Children to Evaluate Abnormalities of Pacemaker Function not Apparent at Rest

The purpose of this study was to evaluate the use of exercise testing in identifying abnormalities of pacemaker function and in confirming set parameters not apparent at rest in children with implanted atrial synchronous physiologic pacemakers. Maximal exercise tests were performed on 24 children (15 boys, 9 girls) from 4.5 to 18 years of age (median =15) with physiologic pacemakers. The lower rule limit was observed before or following testing in 19 of 24 cases. In each case this correlated with the set lower rate limit. The upper rate limit was readied in 10 of 24 cases and was found to be lower than that programmed in one case in which a long atrial refractory period had limited the upper rate limit. Six children reached the maximum upper rate limit to which their pacemaker could be programmed. No abnormalities of atrial capture or ventricular capture occurred during exercise testing. Ventricular sensing was normal in each case. Atrial sensing was observed to be normal in 15 of the 24 cases. Two patients had decreased atrial sensing with exercise. Reversion to the “noise rate” due to myopotential inhibition was found in seven other cases. Subsequent tests on two of these children showed normal sensing. We conclude that: (1) maximal exercise testing identifies aspects of pacemaker function not apparent at rest; decreased atrial sensing and myopotential inhibition are the problems most commonly observed; (2) maximal exercise testing is of value in confirming programmed pacemaker parameters in a population of children with physiologic pacemakers; and (3) because six children reached the maximum upper rate limit of the pacemaker, higher upper rate limits than those currently available may be optimal for pacing in children. Exercise testing is recommended in follow‐up of the child with a physiologic pacemaker.

Aortico-left ventricular tunnel with ventricular septal defect: two-dimensional/Doppler echocardiographic diagnosis.

Aortico-left ventricular tunnel is a rare congenital anomaly that presents as aortic regurgitation and congestive heart failure in childhood. Its association with a ventricular septal defect is even more rare. Because of the distortion of the normal anatomy around the aortic valve and the rarity of this combination of defects, the diagnosis of aortico-left ventricular tunnel with ventricular septal defect may be difficult. The two-dimensional and Doppler echocardiographic findings of aortico-left ventricular tunnel are described.

Balloon atrial septostomy for total anomalous pulmonary venous return.

During the 2-year period July I970 to July I972, balloon atrial septostomy was performed in I2 patients with total anomalous pulmonary venous return, ranging in age from 4 days to I year, and in weight from 2 27 to 6 8o kg. After septostomy, 9 of the I2 patients were improved both clinically and haemodynamically. Of these 9 patients, I died inexplicably I week after the septostomy. In the remaining 8 patients, improvement was maintained during follow-up ranging from 7 months to 2 years. Repeat cardiac catheterization in 4 patients documented continued haemodynamic improvement. Of the I2 patients, 3 were not helped by the septostomy and required operation within a few days. In 2 of these infants, the opening created by the septostomy was found at operation to be too small to have been considered beneficial, yet both of these patients had had less than a i mmHg mean atrial pressure gradient before septostomy. The third patient, who had infradiaphragmatic return, had a large interatrial communication confirmed at operation. Based on the results achieved in these patients, balloon atrial septostomy is now recommended at the time of the initial cardiac catheterization in all infants with total anomalous pulmonary venous return. The procedure is less likely to be successful in infants over 3 months of age, and in those with infradiaphragmatic pulmonary venous return. The haemodynamic improvement obtained by successful septostomy in the young infant should allow delay of operation until a more optimal age.

Severe Takayasu's arteritis of the pulmonary arteries: Report of a case with successful surgical treatment

Although involvement of the aorta and its large branches is more common, Takayasus arteritis involving the pulmonary arteries is well recognized. This report describes an adolescent girl with an uncommonly severe form of Takayasus arteritis involving the pulmonary arteries. A successful surgical treatment is presented.

Intracardiac undifferentiated sarcoma in infancy

A rare case of an intracardiac undifferentiated sarcoma in a 3 month old infant is described together with the clinical, angiographic, echocardiographic, surgical and histopathologic findings. The tumor was successfully removed surgically, and monthly echocardiographic follow-up is being performed.

Cardiac catheterisation in infants weighing less than 2500 grams

OBJECTIVES To investigate the indications for, and outcome of, cardiac catheterisation in infants weighing less than 2500 g at a single institution over an 8-year period. PATIENTS AND METHODS We assessed all infants who were less than 2500 g at the time of cardiac catheterisation at Texas Childrens Hospital from January 1993 to January 2001. Comparisons of morbidity and mortality were drawn with an equivalent number of infants of similar age weighing greater than 2500 g seen over the same period of time. RESULTS We performed interventional procedures in 22, and diagnostic catheterisations in 12 infants weighing less than 2500 g. Interventions included pulmonary valvoplasty in six patients, balloon angioplasty of critical coarctation in one, aortic valvoplasty in two, septostomy in ten, and coil occlusion of an arteriovenous malformation, redirection of a subclavian venous line, and coil occlusion of a patent arterial duct in one patient each. The median age at catheterisation was 5 days for children less than 2500 g, and 10 days for those above 2500 g. The median weights were 2.3 kg and 3.3 kg, and the median gestational ages were 35 weeks and 38 weeks, for the two respective groups. Of those weighing less than 2500 g, two died (6%), with no deaths occurring in those weighing more than 2500 g. In 3 patients weighing less than 2500 g (9%), there was vascular compromise, one child with bilateral femoral venous obstruction requiring fasciotomy compared, to one in the group weighing greater than 2500 g (2%). CONCLUSION There is a significantly increased risk of mortality and vascular compromise in infants weighing less than 2500 g. Interventional catheterisation in these infants may be lifesaving, but given the aforementioned risks, diagnostic catheterisation should be deferred if possible in favor of noninvasive modalities.