Exercise Correlates of Electrophysiologic Assessment of Sinus Node Function in Young Individuals.

This study evaluated prospective exercise correlates of sinus node function in young individuals. Subjects for this study were 25 children and young adults who required cardiac catheterization for a symptomatic arrhythmia. Measurements of sinus node function at elechophysiological catheterization were the sinus node recovery time (SNRT) and sinoatrial conduction time (SACT). Maximal exercise testing was performed using a Bruce treadmill protocol the day prior to cardiac catheterization. Exercise measurements included resting heart rate, peak heart rate, cardiac acceleration from rest to 3 minutes, from rest to 6 minutes, from rest to peak, and from 3 to 6 minutes, cardiac deceleration from peak to 1 minute postexercise, deceleration for each minute of recovery, recovery heart rates for each of 5 minutes postexercise, heart rate at which respiratory exchange ratio >1.0 and slope of the heart rate - VO2 curve. Exercise testing did not predict intracardiac measures of sinus node function either as a group ("normal" vs. "abnormal" groups) or individually.

SUCCESSFUL SURGICAL MANAGEMENT OF CONGENITAL ARTERIOVENOUS FISTULA OF THE SUBCLAVIAN ARTERY: CASE REPORT.

A 10-month-old infant was found to have an isolated congenital arteriovenous fistula between the right subclavian artery and vein. Ligation of the fistula resulted in complete anatomic correction and rapid resolution of cardiomegaly.

Pericardial effusion and tamponade in infants with central catheters.

OBJECTIVE: To describe the clinical presentation, cause, and outcome of central venous catheter (CVC)-related pericardial effusions (PCE) in infants. METHODS: A retrospective case review was conducted of CVC-related PCE at university and private neonatal intensive care units. Data from our cases were combined with published case reports and included clinical presentation and outcome; biochemical evaluation of pericardial fluid; days until diagnosis; cardiothoracic ratios; and CVC characteristics, insertion site, and tip placement site. RESULTS: In our cases, 6 different neonatology groups cared for 14 patients at 6 different hospitals in 2 cities. These data were combined with 47 cases reviewed from the literature. Pericardial fluid was obtained in 54 cases from the combined group and was described qualitatively as consistent with the infusate in 53 of 54 cases (98%). Biochemical analysis was performed in 37 cases, and in 36 of 37 cases (97%), the pericardial fluid was consistent with the infusate. The median gestational age at birth was 30.0 weeks (range: 23.5-42). The median time from CVC insertion to diagnosis was 3.0 days (range: 0.2-37; n = 59). Sudden cardiac collapse was reported in 37 cases (61%), and unexplained cardiorespiratory instability was reported in 22 cases (36%). The CVC tip was last reported within the pericardial reflections on chest radiograph in 56 cases (92%) at the time of PCE diagnosis. The mean cardiothoracic ratio increased 17% (n = 14). No patients died among our cases. Among the reviewed cases, 45% mortality was reported. For the combined group, mortality was 34%. For the combined group, mortality was 8% (3 of 37) in the patients who underwent pericardiocentesis versus 75% (18 of 24) for the patients who did not. In 21 patients, the catheter was withdrawn and remained in use. Survivors and nonsurvivors had comparable gestational age at birth, birth weight, days to PCE diagnosis, and day of life of PCE symptoms/diagnosis. Access site, catheter type, and catheter size were not associated with mortality. An association between larger catheters and shorter time to PCE may be present. Access site and catheter type were not associated with time to PCE. Autopsy specimens reported 6 cases of myocardial necrosis/thrombus formation, 9 cases of perforation without myocardial necrosis/thrombus formation, and 2 cases in which both were reported. CONCLUSIONS: The pericardial fluid found in CVC-associated PCE is consistent with the infusate. We speculate that there are several mechanisms, ranging from frank perforation that seals spontaneously to CVC tip adhesion to the myocardium with diffusion into the pericardial space. Routine radiography should be performed, and the CVC tip should be readily identifiable. The CVC tip should remain outside the cardiac silhouette but still within the vena cavae (approximately 1 cm outside the cardiac silhouette in premature infants and 2 cm in term infants). A change in cardiothoracic ratio may be diagnostic of a PCE, and pericardiocentesis is associated with significantly reduced mortality. Increased awareness of this complication may decrease the mortality associated with CVC-related PCE.

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 Children's 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.

Echocardiographic presentations of endocarditis, and risk factors for rupture of a sinus of Valsalva in childhood.

BACKGROUND: In recent years, the diagnosis of infective endocarditis has been enhanced by the use of echocardiography. We sought, therefore, to review its effect on the management of endocarditis in children. METHODS: We reviewed all the patients presenting to our institution for evaluation for infective endocarditis from May 1994 to January 2002. The patients were stratified according to whether or not they had congenitally malformed hearts. RESULTS: Of the 90 referred patients identified, 46 (51%) had positive ultrasonic findings. Of these, we excluded 26 patients because of the presence of indwelling lines. The remaining 20 patients with features of endocarditis had a median age of 6.5 years, and a range from 0.14 to 8.5 years. There were 4 patients with normal hearts, and 16 with congenital cardiac malformations. We identified rupture of a sinus of Valsalva in four patients, with rupture into the left ventricle in two, and into the right ventricle and right atrium in one each. The mitral valve was involved in six patients, the aortic valve in another six, including all four with rupture of the sinus of Valsalva, both mitral and aortic valves in three, the pulmonary trunk in three patients, and the tricuspid valve and a Blalock-Taussig shunt in one patient each. Organisms isolated included Streptococcus mitis in 4 patients, Streptococcus pneumoniae in 2 patients, Streptococcus sanguis in 1, Staphylococcus aureus in 3, Staphylococcus epidermidis in 1, and Enteroccocus in 2. Cultures proved negative in 7 patients. Surgical intervention was needed in 12 patients, and one died (5%). Only the left-sided chambers were involved in those with normal hearts. Both patients infected with Streptococcus pneumoniae had rupture of a sinus of Valsalva. CONCLUSION: Involvement of the left-sided chambers is more likely in structurally normal hearts, and in cases with rupture of a sinus of Valsalva, in which case infection with Streptococcus pneumonia should be suspected.