The Mechanisms of Tachyarrhythmias in Infants with Structurally Normal Heart

BACKGROUND AND OBJECTIVES: The mechanisms of supraventricular tachycardia (SVT) in children are known to have age-dependent distributions. However, the distribution of the mechanisms of tachyarrhythmia, as a whole, is not known in infants and children. The aim of this study was to evaluate the mechanisms of tachyarrhythmia in infants with a structurally normal heart. SUBJECTS AND METHODS: We retrospectively reviewed the mechanisms of tachycardia in 56 children with structurally normal hearts, who had had a tachyarrhythmia in infancy. The mechanisms of tachycardia were confirmed in surface electrocardiogram and by transesophageal, or transvenous, electrophysiological study. RESULTS: The majority of tachycardia during infancy were SVT, in 50 of the 56 (89%). In the infants with SVT, 29 (58%) had atrioventricular reentrant tachycardia using an accessory pathway, With a manifested accessory pathway were in 13 of the 29. Primary atrial tachycardia was found in 19 (38%: a chaotic atrial tachycardia in 10, an atrial flutter in 5 and an atrial ectopic tachycardia in 4). 6 (11%) had a ventricular tachycardia, and of these 5 had a verapamil-sensitive idiopathic left ventricular tachycardia. The most infrequent tachycardia during infancy was an atrioventricular nodal reentrant tachycardia, which occurred in only 2 (4%). 39% of the tachycardia during infancy occurred in the neonatal period. Atrioventricular nodal reentrant and ventricular tachycardia were not found during the neonatal period. CONCLUSION: The most frequent mechanism of tachycardia during infancy was SVT related, with an accessory pathway. Primary atrial and ventricular tachycardia were also found in nearly half the infants, and these were sometimes difficult to manage without understanding their precise mechanism.

Counter-Current Aortography Using Peripheral Arteries in Small Infants and Neonates with Aortic Arch Obstruction

BACKGROUND: Diagnosis of aortic arch obstruction can be made with two-dimensional and Doppler echocardiography in most cases.However,not infrequently,clear imaging of the aortic arch can not be obtained,particularly in sick neonates and young infants from a number of reasons and heart catheterization and angiography carries significant risk in sick babies.Therefore it is the purpose of this study to assess the feasibility and safety of counter-current aortography through a peripheral artery in young infants and neotates with suspected aortic arch obstruction. METHOD: We studied 56 patients with suspected aortic arch anomaly at Asian Medical Center from Feburary 1990 to April 1997.First choice for the peripheral artery was radial artery on the same side as the aortic arch,followed by brachial artery and axillary artery.Small 24 gauge plastic cannula was inserted and special attention was given to ensure that the peripheral artery,plastic cannula,and a syringe containing contrast material are all in the same plane.1ml/kg of contrast material was injected by rapid hand injection and biplane cineangiograms were taken at 60 frame/second. RESULTS: Fifty six patients underwent 58 angiograms.Age ranged from 5-255 days(median 30 days) and body weight nanged from 2.1-5.4kg(mean3.4kg).There were 27 males and 29 females.Arteries used were:Radial artery in 37,brachal artery in 19,and axillary artery in 2 cases.Peripheral arteries were ipsilateral side as the aortic arch in 54,contralateral side in 2 and bilateral in 2 cases.In 8 patients heart catheterization was done because of inadequate visualization of aortic arch anatomy and/or need for evaluating other defects.In 48 patients who had periperal angiography only,fluoroscopic time ranged from 0.6 to 3.5 minutes and total procedure time ranged from 10 to 15 minutes.Among these 48 patients,only 11 patients(23%) were given intraveous sedation and 37 patients(77%) did not recieve any sedation.Diagnosis of aortic arch anomaly was aortic coarctation in 38,aortic interruption in 10 and nomal aortic arch in 8 patients.Aortic arch anatomy was well demonstrated in all cases where injected artery was on the same side as the aortic arch.In patients who had angiograms through peripheral arteries contralateral to the side of the aortic arch did not haveadequate visualization of the arch.Compression of the carotid artery did not enhance the imaging of the arch.Simultanous bilateral angiography did not improve the imaging quality as compared to ipsilateral artery angiography.Transient complication,related to cannulation,e.g.,prolonged bleeding was seen in only one patient with aortic interruption.Circulation on the upper extremities was normal after angiography in all patients. CONCLUSION: Counter-current aortography using 24 gauge plastic cannular through peripheral artery is feasible,rapid,safe,economic and relatevely non-invasive procedure and provides adquate imaging of aortic arch obstruction in infants and neonates without risk of heart catheterization and angiography.We,therefore,recommend this procedure in selected patients in whom echocardiographic imaging alone is not conclusive for planning corrective sursery.