The clinical course of multifocal atrial tachycardia in infants and children.

OBJECTIVES: This study outlines the clinical course, treatment and the late outcome of infants and children with multifocal atrial tachycardia (MAT). BACKGROUND: Multifocal atrial tachycardia is defined by three distinct P-waveforms, irregular P-P intervals, isoelectric baseline between P-waves and rapid rate on an electrocardiogram. Several smaller prior reports have described pediatric patients with MAT, but their long-term outcome has not been fully assessed. METHODS: The clinical records, echocardiograms and long-term follow-up of patients with MAT were reviewed and compared to previous reports of MAT. RESULTS: Fourteen boys and seven girls (median age 1.8 months) presented with MAT. At diagnosis, six patients had respiratory illness, of whom two were critical. Ten were asymptomatic. Seven patients had structural heart disease (SHD), one of whom died. Four of 15 patients (27%) with echocardiograms had diminished ventricular function. Ventricular rates were 111 to 253 beats/min (mean 181 beats/min). Median duration of the arrhythmia was 4.9 months (mean 6.7 months). Electrical cardioversion was attempted in 4 patients without success and 15 patients received antiarrhythmic medication. Seventeen patients were followed for a mean of 60 months. Four patients were lost to follow-up. There were no late arrhythmias. CONCLUSIONS: The majority of children with MAT are healthy infants under one year of age; a few may exhibit mild to life-threatening cardiorespiratory disease. Less often, MAT accompanies SHD. Mild ventricular dysfunction may be observed in the presence of MAT, but symptoms are few and resolution is generally complete. Response to antiarrhythmic agents is mixed, and cardioversion is of no avail. Finally, long-term cardiovascular and developmental outcome depends principally on underlying condition; for otherwise healthy children, it is excellent.

Comparison of single and double balloon valvuloplasty in children with aortic stenosis.

To compare the effectiveness of the single and double balloon techniques, the short-term results of percutaneous balloon valvuloplasty were assessed in two consecutive groups of children with valvular aortic stenosis. In 16 children (aged 3 months to 17 years) the single balloon technique was utilized; the ratio of balloon diameter to valve anulus diameter was 0.96 +/- 0.03 (mean +/- SEM). In 11 children (aged 3 months to 21 years) the double balloon technique was utilized in which two balloons are positioned across the valve and inflated simultaneously; the ratio of the balloon diameter sum to valve anulus diameter was 1.32 +/- 0.05. The groups were similar in age, weight, cardiac output, prevalvuloplasty gradient and valve anulus diameter. Overall, valvuloplasty reduced the peak systolic gradient by 53% from 80 +/- 4 to 38 +/- 3 mm Hg (p less than 0.0001). In the single balloon group the gradient decreased from 82 +/- 6 to 46 +/- 4 mm Hg (p less than 0.0001), whereas in the double balloon group the gradient decreased from 76 +/- 5 to 26 +/- 4 mm Hg (p less than 0.0001). The peak systolic gradient after valvuloplasty was 43% lower in the double balloon group (p less than 0.01). Furthermore, the single balloon technique reduced the gradient by an average of 43% compared with a 67% reduction with the double balloon technique (p less than 0.001). The short-term complications of valvuloplasty were similar, with an increase in aortic insufficiency occurring in three children in each group.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous balloon angioplasty for native coarctation of the aorta.

Twenty-six children, aged 5 weeks to 14.7 years, underwent percutaneous balloon angioplasty for a discrete native coarctation of the aorta. The procedure reduced the systolic coarctation gradient acutely in all children. The mean systolic gradient decreased by 75%, from 48.6 +/- 2.4 before to 12.3 +/- 1.9 mm Hg after angioplasty (p less than 0.001). Long-term results were evaluated in 14 children by follow-up catheterization 12 to 26 months (mean 15.3) after angioplasty. At follow-up, the residual gradient averaged 11.7 +/- 3.7 mm Hg (range -5 to 36) and had not changed from that measured immediately after angioplasty (p = 0.64). Compared with preangioplasty values, the systolic pressure in the ascending aorta had improved substantially at follow-up (116.0 +/- 3.2 versus 143.9 +/- 3.1 mm Hg, p less than 0.001). On the basis of follow-up data, two groups of children were identified: Group 1 consisted of nine children with a good result, defined as a residual gradient less than 20 mm Hg and no aneurysm; Group 2 consisted of five children with a poor result, four with a residual gradient greater than 20 mm Hg (range 25 to 36) and one with an aneurysm at the dilation site. There was no statistical difference between the two groups in age at angioplasty, balloon size, ratio of balloon to isthmus diameters, follow-up duration, heart rate or cardiac output. However, of the four children with a residual gradient greater than 20 mm Hg, two were the youngest in the study, and in two the aorta was inadvertently dilated with a balloon 4 to 5 mm smaller than the isthmus diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal cerebral hemodynamics in preterm infants with patent ductus arteriosus.

Blood flow patterns in the anterior cerebral arteries were studied in eight preterm infants with patent ductus arteriosus and left-to-right shunts. A noninvasive Doppler technique was used to obtain the blood flow patterns and to calculate a pulsatility index. Advancing diastolic blood flow was decreased in all eight infants, and two demonstrated retrograde anterior cerebral artery flow during diastole. Following ductal closure, the diastolic flow in the anterior cerebral arteries increased significantly, reaching levels seen in normal infants. These observations demonstrate that infants with patent ductus arteriosus and left-to-right shunts may have abnormal cerebral hemodynamics which return to normal following ductal closure.

Ventricular tachyarrhythmia due to cardiac sarcoidosis in a child.

Cardiac involvement by systemic sarcoidosis is well known, but occurs rarely. It usually manifests as either heart block, heart failure due to direct myocardial involvement, or cor pulmonale. We present the case of a patient with cardiac sarcoidosis who had ventricular tachycardia and congestive heart failure. Although there was other organ system involvement, the cardiac manifestation was the first to become clinically apparent. Therapy consisted of quinidine sulfate to control the arrhythmias and chronic diuretic therapy to control congestive heart failure. Steroid therapy was initially associated with recurrence of the ventricular tachycardia and was discontinued. It was reinstituted 18 months later when other organ system involvement developed with no recurrence of the ventricular tachyarrhythmia. The patient responded well to therapy and is currently doing well. This case is presented to illustrate a somewhat unusual, but nevertheless important, etiology of ventricular tachyarrhythmias. The recognition of underlying sarcoidosis is critical because of the propensity for other organ system involvement by this disease process.

Evaluation of pacemaker pulse generator and patient longevity in patients aged 1 day to 20 years.

The longevity of pediatric patients requiring pacemakers and the survival rates of the implanted generators were evaluated. From January 1970 to December 1985, 96 patients aged 1 day to 20 years underwent 162 pulse generator implantation procedures. Indication for initial implantation was surgically induced heart block in 52 patients, sick sinus syndrome in 20, congenital complete heart block with symptoms of low cardiac output in 19 and tachydysrhythmia control in 5. Modal age at initial implantation was less than 1 year; median age was 5 years. During this period 90 generators were removed from service: 49 (54%) because of generator failure, 22 (24%) because the patient died, 12 (13%) because of elective upgrade at the time of lead failure or cardiac surgery, 5 (6%) because of generator pocket infection and 2 (2%) because of manufacturer's recall. Pulse generators were separated into 4 groups based upon generator technology. Group I (n = 16) were asynchronous units with mercury-zinc batteries; group II (n = 18) were single-chamber demand units with mercury-zinc batteries; group III (n = 14) were single-chamber demand units with rechargeable batteries; and group IV (n = 114) were single- or dual-chamber demand units with lithium batteries. Patient survival rate was 84% at 6 months and 70% by 109 months. There was no further decrease to the end of the study period. Six-month generator survival rate was 82% for all groups, mostly a reflection of patient deaths.(ABSTRACT TRUNCATED AT 250 WORDS)

Epicardial ventricular pacemaker electrode longevity in children.

While epicardially implanted electrodes remain the most widely used in children for ventricular pacing, their expected longevity remains unknown. The longevity of 126 such electrodes implanted from January 1970 through December 1985 was evaluated in 81 children followed up for 1 to 192 months (median 63). Age at initial implant was 1 day to 18 years. Each child had from 1 to 5 electrodes implanted; 85 electrodes were of the sutureless helical type and 41 were of the suture-fixated type. Electrode failure, defined as loss of capture with a high pacing threshold found at operation or sensing failure, occurred in 38 electrodes from 1 to 157 months postimplant (median 37). Mode of failure was high threshold with high impedance (n = 15), low impedance (n = 6), complete inability to pace (n = 8), sensing failure (n = 2) or high threshold with no measure of impedance (n = 7). Actuarial life table analysis of electrode longevity showed a 88 +/- 3% (standard error of the estimate) survival rate at 6 months with no significant decrease until 53 months (75 +/- 5%, p less than 0.05). There was then a gradual steady decrease to 49 +/- 7% by 101 months. From 101 to 157 months no significant decrease occurred. Survival rate decrease was greatest within the first 6 month period postimplant (-12%). Electrodes surviving to 6 months are highly likely to survive until 53 months. Of those surviving to 53 months, 74% should survive to 120 months.

Usefulness of the Doppler mean gradient in evaluation of children with aortic valve stenosis and comparison to gradient at catheterization.

To assess the usefulness of the Doppler mean gradient as a noninvasive indicator of the need for intervention, 33 children (ages 3 months to 20 years) with valvular aortic stenosis (AS) underwent a 2-dimensional and Doppler echocardiographic examination a median of 1 day before cardiac catheterization. The clinical decision for intervention was based on finding a catheterization peak-to-peak pressure gradient of greater than 75 mm Hg or from 50 to 75 mm Hg in the presence of symptoms or an abnormal exercise treadmill test result. Of the 33 patients, 23 required intervention. The decision for intervention was compared to the Doppler mean gradient, and the Doppler peak and mean gradients were compared to the catheterization peak-to-peak gradient. All 12 patients with a Doppler mean gradient greater than 27 mm Hg had intervention and had a catheterization peak-to-peak gradient of greater than or equal to 75 mm Hg. All 3 patients with a Doppler mean gradient less than 17 mm Hg had no intervention and had a peak-to-peak gradient less than 50 mm Hg. The remaining 18 patients with Doppler mean gradients between 17 and 27 mm Hg comprised an intermediate group in whom the Doppler mean gradient alone did not predict the need for intervention. From a chi-square table, a Doppler mean gradient greater than 27 mm Hg predicted the need for intervention with 100% specificity (no false positives) and 52% sensitivity (11 false negatives).(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting use of the Doppler-determined time from flow onset to maximal pulmonary artery velocity for measurement of pulmonary artery pressure in children.

Measurement of the time from onset to maximal or peak velocity (TPV) of pulmonary artery (PA) flow has been proposed as a noninvasive means of determining PA pressure. The effects of age, heart rate, increased PA pressure and flow, pulmonary valve obstruction and altered PA vascular resistance on this measurement were evaluated. In 84 children, aged 1 day to 18 years, TPV was measured using continuous-wave Doppler echocardiography. The children were separated into 3 groups. Group I (n = 33) consisted of children with no cardiovascular abnormalities. Group II (n = 33) consisted of children with a variety of cardiovascular diseases producing varying PA pressures and flows. Group III (n = 18) consisted of children who had valvular pulmonic stenosis with PA to right ventricular gradients greater than 40 mm Hg. Doppler studies of group II and III patients were performed in conjunction with measurement of PA pressures and flows at the time of cardiac catheterization. In group I TPV showed a significant negative linear correlation with heart rate (r = -0.86, p less than 0.001). The ratio of observed TPV to predicted TPV (TPVN) determined using the regression equation for TPV vs heart rate or TPV/TPVN was heart rate- and age-independent (p greater than 0.1) and ranged from 0.81 to 1.31 (mean 1.005). In group II TPV/TPVN was inversely related to the natural log of the PA pressures (systolic, r = -0.91; mean, r = -0.87; diastolic, r = -0.82; all p less than 0.01), whether pressure elevation was due to increased flow, resistance or left atrial hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Two-dimensional and Doppler echocardiographic evaluation after arterial switch repair in infancy for complete transposition of the great arteries.

The most recent postoperative echocardiographic examinations of all children who underwent arterial switch repair of transposition of the great arteries from August 1985 to December 1987 were reviewed. The patients included 35 children whose age at operation was 12 +/- 16 days and whose weight was 3.6 +/- 0.4 kg. Thirty-three patients are alive and well; 1 died intraoperatively and 1 died immediately postoperatively. The time of the follow-up echocardiographic examination ranged from 1 day to 2.5 years (mean 9.2 months) with 11 patients examined greater than 1 year after surgery. Complete examination of the repair site was possible in all patients. Echocardiographic visualization of distortion of the great arteries at the suture lines was seen in all patients; however, Doppler evidence of hemodynamically significant obstruction at the repair site was uncommon. On Doppler examination in the surviving 33 patients, 16 had no supravalvular pulmonary stenosis and 14 had mild to moderate supravalvular pulmonary stenosis with peak systolic pressure gradients ranging from 16 to 56 mm Hg (mean 31). Three patients had severe supravalvular pulmonary stenosis and peak systolic pressure gradients of 66, 74 and 77 mm Hg (2 have had reoperation, 1 is awaiting surgery). On Doppler examination, 4 patients had mild supravalvular aortic stenosis with peak systolic gradients ranging from 10 to 29 mm Hg. Doppler gradients were confirmed in 10 patients who had catheterization 12 +/- 3 months after surgery. Three patients had mild pulmonary regurgitation by Doppler examination, 5 had mild aortic regurgitation, 4 had mild tricuspid regurgitation and 2 had mild mitral regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler evaluation of homograft valved conduits in children.

To assess the flow characteristics of homograft valved conduits in the immediate postoperative period, 69 children with 71 homograft conduits underwent 2-dimensional and Doppler echocardiographic examination at 1 to 40 days (mean 8) after surgery. Of the 71 conduits studied, 19 were aortic and 52 were pulmonary homograft valved conduits. Two aortic homograft valved conduits were inserted in the aortic position, whereas all remaining homografts were placed in the pulmonary position. On the immediate postoperative echocardiogram, 25 (35%) of the conduit valves had no regurgitation and 44 (62%) had 1+ (mild) regurgitation. Two pulmonary valved conduits (3%) in the pulmonary position had 2+ (moderate) regurgitation and right ventricular dimensions greater than 95% for body surface area. The peak velocity across the homograft valve was normal (less than 1.3 m/s) in 58 valves (82%). In the remaining 13 valves, peak velocity ranged from 1.4 to 2.6 m/s. No homograft valve had a peak velocity greater than 2.6 m/s in the immediate postoperative period. To assess the fate of homograft valved conduits in the intermediate-term follow-up period, 38 children with 38 conduits had a repeat echocardiogram at 6 to 25 months (mean 15 +/- 6) after surgery. Of the 38 conduits examined, 10 (26%) had no regurgitation, 25 (66%) had 1+ regurgitation and 3 (8%) had 2+ regurgitation. Progression of the amount of regurgitation occurred in 11 (29%) patients. At the follow-up examination, peak velocity was less than or equal to 1.4 m/s across 34 conduit valves, between 1.4 and 2.6 m/s across 3 valves and greater than 2.6 m/s across 1 valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulsed Doppler assessment of left ventricular diastolic filling in children with left ventricular outflow obstruction before and after balloon angioplasty.

To assess left ventricular (LV) diastolic filling in children with pressure overload hypertrophy, 12 patients with LV outflow obstruction (7 with aortic valve stenosis and 5 with aortic coarctation) and 12 healthy, age-matched control subjects were examined. Each child underwent M-mode echocardiography and pulsed Doppler examination of the LV inflow. The patients with LV outflow obstruction had cardiac catheterization and balloon angioplasty. Their echo/Doppler examinations were performed in the catheterization laboratory before and immediately after balloon angioplasty. From the M-mode echocardiogram, the LV cavity dimensions and wall thicknesses, LV mass and shortening fraction were measured. The following measurements were made from the Doppler recording: peak velocities at rapid ventricular filling (peak E) and during atrial contraction (peak A), ratio of peak E to peak A velocities, total area under the Doppler curve, percent of the total Doppler area occurring in the first one-third of diastole (0.33 area fraction), percent of the total area occurring under the E wave (E area fraction), percent of the total area occurring under the A wave (A area fraction) and the ratio of E area to A area.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological rationale for a bidirectional cavopulmonary shunt. A versatile complement to the Fontan principle.

The original Fontan procedure included a classic superior vena cava-to-right pulmonary artery (Glenn) shunt. Subsequent experience demonstrated that this anastomosis was not essential and was an unnecessary commitment of the larger right pulmonary circulation to the smaller blood volume of the superior vena caval return. With application of the Fontan principle to more complex cardiac malformations, there has been a reconsideration of possible benefits of a cavopulmonary shunt in selected patients. A modified shunt from the divided end of the superior vena cava to the side of the undivided right pulmonary artery utilized in 21 patients is described. This shunt is designed to allow bidirectional pulmonary arterial distribution of both superior vena caval inflow and right atrial outflow after completion of the Fontan procedure. Twelve patients had the bidirectional shunt performed prior to a Fontan operation; five of these had a subsequent atriopulmonary connection and seven await operation. Eight patients had construction of this shunt at the time of their Fontan procedure. One patient had a bidirectional shunt constructed following atriopulmonary anastomosis to help relieve right atrial outflow obstruction. Two patients with univentricular heart undergoing simultaneous Fontan procedure and a bidirectional shunt died while in the hospital. The remaining 19 patients have been followed up for 2 months to 9 years with one late sudden death at 9 years. There have been no bidirectional cavopulmonary shunt failures, stenoses, kinks, or recognized pulmonary arteriovenous malformations. Postoperatively, eight patients had assessment of pulmonary distribution of shunt blood flow by angiography. Seven of these patients were also evaluated by radionuclide angiography. Superior vena caval blood flow via the bidirectional cavopulmonary shunt tended to be greater to the right lung, but bilateral pulmonary flow was documented in all but one patient. After Fontan operation, six of seven patients tested also demonstrated bilateral distribution of atriopulmonary flow. We concluded from our experience that this modified shunt provides excellent relief of cyanosis, allows bidirectional pulmonary distribution of both superior vena caval return and also the right atrial blood flow after atriopulmonary connection, and may be done before, with, or after a Fontan procedure and is compatible with all currently recommended modifications. Perioperative hemodynamic adjustments to the Fontan procedure may be improved by reducing atrial volume, and this may also be of potential benefit in the long-term adaptation to Fontan physiology by minimizing atrial distention.

Tetralogy of Fallot associated with uncommon lesions.

A patient presented with a a unique combination of cardiovascular abnormalities: tetralogy of Fallot, absent pulmonary valve, stenosis of peripheral pulmonary arteries, and partial anomalous pulmonary venous connection to the azygos vein. The salient aspects and associated lesion of each of these abnormalities are described.

Pediatric cardiovascular imaging.

Cardiovascular imaging in children has stressed acquisition of information with the least possible stress to the child. Improvements in noninvasive imaging have now largely supplanted the use of invasive techniques for diagnostic imaging. During the past year, major improvements in the diagnosis of complex cardiac malformations have occurred together with the extension of such techniques to the operating room. This review focuses on improvements in echocardiography, color flow imaging, and magnetic resonance in the imaging of complex cardiovascular defects, both intra- and extracardiac. Imaging of abnormalities of the atrioventricular region, intracardiac and coronary artery fistulae, homograft valved conduits, and pulmonary artery anatomy is discussed. The use of magnetic resonance imaging for the evaluation of pulmonary artery anatomy, ventricular septal defects, and aortic arch abnormalities is reviewed, as is the use of magnetic resonance imaging in small infants. Finally, the use of both epicardial and transesophageal echocardiography in the operating room for evaluation of the adequacy of surgical repair is reviewed. These studies demonstrate the ability of these techniques to provide information critical for the proper management of children undergoing cardiac surgery.

Partial anomalous pulmonary venous connection to the azygos vein with intact atrial septum.

The case of a 13-year-old girl with an unusual form of partial anomalous pulmonary venous connection is reported. Cardiac catheterization revealed anomalous connection of the right pulmonary veins to the azygos vein and an intact atrial septum. Rationale for nonsurgical management and four-year follow-up results are discussed.