Modified Norwood operation for hypoplastic left heart syndrome

BACKGROUND

We examined early results in infants with hypoplastic left heart syndrome undergoing the Norwood operation with perioperative use of inhaled nitric oxide and application of extracorporeal membrane oxygenation.

METHODS

Medical records were reviewed retrospectively.

RESULTS

Between April 1997 and March 2001, 50 infants underwent a modified Norwood operation for hypoplastic left heart syndrome. Mean age at operation was 7.5 +/- 5.7 days, and mean weight was 3.1 +/- 0.5 kg. Five infants had a delayed operation because of sepsis. The mean diameter of the ascending aorta by echocardiography was 3.6 +/- 1.8 mm. Ductal cannulation was used to establish cardiopulmonary bypass in all patients. Mean circulatory arrest time was 39.4 +/- 4.8 minutes. The size of the pulmonary-systemic shunt was 3.0 mm in 6 infants, 3.5 mm in 37, and 4.0 mm in 7. Infants with persistent hypoxia (partial pressure of oxygen < 30 mm Hg) received nitric oxide after they were weaned from cardiopulmonary bypass. Extracorporeal membrane oxygenation was initiated in 8 infants in the pediatric intensive care unit primarily for low cardiac output and in 8 in the operating room because of the inability to separate them from cardiopulmonary bypass. The 30-day mortality rate was 22% (11 of 50 patients), and the hospital mortality rate was 32% (16 of 50 patients). Mean follow-up was 17 months. Ten patients (20%) underwent stage-two repair, with one operative death. One survivor had a Fontan procedure, and 2 underwent heart transplantation, with one death.

CONCLUSIONS

Early application of extracorporeal membrane oxygenation for hemodynamic instability and selective use of nitric oxide for persistent hypoxia in the immediate postoperative period may improve survival of patients with hypoplastic left heart syndrome. Renal failure requiring hemofiltration during extracorporeal membrane oxygenation (p < 0.05) and cardiopulmonary arrest in the pediatric intensive care unit (p < 0.05) were predictors of hospital mortality.

Extracorporeal membrane oxygenation in children after repair of congenital cardiac lesions

BACKGROUND

The purpose of this study was to review our experience in the early application of extracorporeal membrane oxygenation (ECMO) in patients requiring mechanical assistance after cardiac surgical procedures.

METHODS

The hospital records of all children requiring ECMO after cardiac operation were retrospectively reviewed, and an analysis of variables affecting survival was performed.

RESULTS

Fifty pediatric patients between May 1997 and October 2000 required ECMO for cardiopulmonary support after cardiac operation. Patients ranged in age from 1 day to 11 years (median age, 40 days). Forty-eight patients underwent repair of congenital cardiac lesions and 2 were included after receiving a heart transplant. Twenty-two children could not be weaned from cardiopulmonary bypass and were placed on ECMO in the operating room for circulatory support. Of the 28 children who required ECMO in the intensive care unit, 10 had ECMO instituted after cardiopulmonary arrest (mean cardiopulmonary resuscitation time 42 minutes; range, 5 to 110 minutes). In infants with single-ventricle physiology, survival to discharge was 61% (11 of 18 patients) as compared with 43% (14 of 32 patients) in those with biventricular physiology. Thirty of the 50 patients (60%) were successfully weaned from ECMO, of which 25 (83%) were discharged home. Overall survival to discharge in the entire cohort was 50%. Extracorporeal membrane oxygenation support greater than 72 hours was a grave prognostic indicator. Overall survival in this group was 36% (9 of 25 patients) compared with 56% (14 of 25 patients) in those with ECMO support less than 72 hours (p < 0.05). Univariate analysis revealed the presence of renal failure, extended periods of circulatory support, and a prolonged period of cardiopulmonary resuscitation as risk factors for mortality. The presence of shunt-dependent flow, operative procedure, and institution of ECMO in the intensive care unit did not alter survival.

CONCLUSIONS

Extracorporeal membrane oxygenation provides effective support for postoperative cardiac and pulmonary failure refractory to medical management. Early institution of ECMO may decrease the incidence of cardiac arrest and end-organ damage, thus increasing survival in these critically ill patients.

Normal human right and left ventricular mass, systolic function, and gender differences by cine magnetic resonance imaging

Our objective was to establish normal ranges of left and right ventricular mass and function with cine magnetic resonance imaging (MRI) and to determine gender differences. Seventy-five healthy subjects (age range 8-55, mean 28 yr) were studied with cine MRI. Ten dogs were imaged for autopsy validation with a mean difference between actual and MRI-determined mass of 0.2 A +/- 8.4 g. Intraobserver and interobserver variability and interstudy variability were 5-6%. All parameters were significantly different between males and females except ejection fraction and the left ventricular mass to end-diastolic volume ratio. Agreement with published autopsy series, including gender differences, was excellent. This study presents normative MRI data that can be used for comparing individual patients and for further study of right and left ventricular interaction.

Retrograde cardiovascular angiography in infants, using a 3.6 French catheter

Diagnostic retrograde arterial catheterization in infants, and small children has been constrained by the risk of arterial thrombosis and the low flow rate of catheters less than #5 French. We performed retrograde arterial catheterization (percutaneous technique in 21 of 24 patients) on 24 infants and small children (median age 3 months, median weight 4.1 kg), using a 3.6 French performed polyethylene catheter. Systemic heparinization was used. Among the group, we performed 23 aortograms, and 4 selective injections into a bronchial artery; all angiograms were of diagnostic quality. Injection rates ranged from 3 cc/sec to 10 cc/sec (median 5 cc/sec) with a peak developed pressure of 300 PSI to 900 PSI (median 700 PSI). No catheter-related complications were encountered during the study. Four of 24 patients developed a decreased pulse, noted immediately following the catheterization; however, pulses returned to normal within 24 hours, and late blood pressure assessment revealed no abnormalities in the catheterized leg. We now recommend this catheter for infants less than 10 kg when the following angiograms are required: 1. retrograde aortography (truncus arteriosus, pulmonary atresia, aortic stenosis, coarctation, coronary anomalies) 2. selective injections of bronchial arteries 3. retrograde catheterization of surgical shunts.

Outcome of preterm infants with congenital heart disease

OBJECTIVES AND STUDY DESIGN

To evaluate the morbidity and mortality of preterm infants with congenital heart disease (CHD), a chart review was performed for infants with CHD, excluding isolated patent ductus arteriosus, who were <37 weeks' gestation, weighed <2500 g, and were admitted to our neonatal intensive care unit from 1976 to 1999 (N = 201).

RESULTS

Patients in the study represented 1.9% of the total neonatal intensive care unit population <37 weeks' gestation and <2500 g. The median gestational age was 33 weeks, and the mean birth weight was 1852 g. CHD diagnosis frequencies were similar to those reported in other large incidence studies, except for a higher percentage of conotruncal defects. The risk of necrotizing enterocolitis was 1.7 times higher and the overall mortality twice as high in our patients compared with patients in the neonatal intensive care unit who did not have CHD. Cardiac surgery (n = 133) was performed on 108 patients. During the recent period of 1985 to 1999, compared with our institution's overall results for CHD surgery, the operative mortality rate was 10.4% versus 5.4% for closed procedures and 25.4% versus 10.5% for open procedures. The actuarial survival rate is 51% at 10 years; survival improved as the study period progressed.

CONCLUSIONS

Infants with both CHD and prematurity did significantly worse than either group alone. Such outcome data are required for proper allocation of resources to care for this high-risk pediatric population.

Long-term outcome in congenitally corrected transposition of the great arteries: a multi-institutional study

OBJECTIVES

The purpose of this study was to determine long-term outcome in adults with congenitally corrected transposition of the great arteries (CCTGA), with particular emphasis on systemic ventricular dysfunction and congestive heart failure (CHF).

BACKGROUND

Patients with CCTGA have the anatomical right ventricle as their systemic pumping chamber, with ventricular dysfunction and CHF being relatively common in older adults.

METHODS

Retrospective analysis of records of 182 patients from 19 institutions were reviewed to determine current status and possible risk factors for systemic ventricular dysfunction and CHF. Factors considered included age, gender, associated cardiac defects, operative history, heart block, arrhythmias and tricuspid (i.e., systemic atrioventricular) regurgitation (TR).

RESULTS

Both CHF and systemic ventricular dysfunction were common in groups with or without associated cardiac lesions. By age 45, 67% of patients with associated lesions had CHF, and 25% of patients without associated lesions had this complication. The rates of systemic ventricular dysfunction and CHF were higher with increasing age, the presence of significant associated cardiac lesions, history of arrhythmia, pacemaker implantation, prior surgery of any type, and particularly with tricuspid valvuloplasty or replacement. Aortic regurgitation (a previously unreported problem) was also relatively common in this patient population.

CONCLUSIONS

Patients with CCTGA are increasingly subject to CHF with advancing age; this complication is extremely common by the fourth and fifth decades. Tricuspid (systemic atrioventricular) valvular regurgitation is strongly associated with RV (anatomical right ventricle connected to aorta in CCTGA patients; systemic ventricle in CCTGA) dysfunction and CHF; whether it is causative or a secondary complication remains speculative.

Long-lasting improvement after septal myectomy for hypertrophic obstructive cardiomyopathy

BACKGROUND

The most effective treatment of symptomatic patients with hypertrophic obstructive cardiomyopathy is still disputed. Treatment options include medical therapy, pacemaker insertion, percutaneous transluminal septal myocardial ablation, mitral valve replacement, and surgical resection of obstructing muscle. The long-term results of the various treatment options are not well defined. We aimed to demonstrate that septal myectomy is efficacious in reducing or abolishing left ventricular outflow tract gradient and leads to long-lasting symptomatic improvement in most patients.

METHODS

Twenty-two consecutive patients had septal myectomy between 1981 and the present. Their records were reviewed to document the details of their preoperative status, hospital course, their subsequent clinical outcome, and current status.

RESULTS

Mean age at operation was 31.3 years. Preoperatively all patients were disabled by typical symptoms despite aggressive medical treatment. Mean resting gradient was 78 mm Hg. Nine patients required simultaneous associated cardiac procedures. There were no perioperative deaths and minimal morbidity. Two patients died at 6 and 9 years postoperatively of congestive heart failure and arrhythmias. Long-term survivors have been followed up for a mean of 6.6 years. Currently all have minimal or no symptoms. The mean resting gradient was 12 mm Hg. No patient has required reoperation for residual obstruction.

CONCLUSIONS

Septal myectomy reduces or abolishes left ventricular outflow tract gradient in hypertrophic obstructive cardiomyopathy. Myectomy provides long-lasting symptomatic improvement in most patients. The clinical status of patients late postoperatively can be affected by arrhythmias and myocardial dysfunction.

Relief of right ventricular to pulmonary artery conduit stenosis using a self-expanding stent

Intravascular stents have recently been used to treat vascular stenoses in congenital heart disease. Size limitations, however, may preclude their use in certain situations. We describe the successful relief of right ventricular to pulmonary artery conduit stenosis in an adult patient late after repair of truncus arteriosus using a larger, self-expanding wall stent.

Noninvasive delineation of normal right ventricular contractile motion with magnetic resonance imaging myocardial tagging

As the importance of the right ventricle in many diseases and conditions has been realized, the need for quantitative assessment of the motion and contraction of the right ventricular free wall (RVFW) has become apparent. This study applied the myocardial tagging magnetic resonance imaging (MRI) technique to the normal RVFW to elucidate normal heterogeneity in RV motion and contractile patterns. The RVFW was divided into three segments (inferior, mid and superior) in each of three slices (apical, mid and basal) to allow for a detailed analysis of the motion and contraction. Percent segmental shortening (PSS) was used to measure the amount of contraction, and a vector analysis was used to quantitate the trajectory of the RVFW through systole. PSS increased monotonically through time to an average across all segments of 12% in the basal slice, 14% in the mid-ventricular slice, and 16% in the apical slice of the heart. The trajectory of the RVFW was characterized by a wave of motion toward the septum and outflow tract. The data provided in this study provide a better understanding of normal RV kinematics and can serve as a comparison for disease states.

Alterations in pulmonary artery flow patterns and shear stress determined with three-dimensional phase-contrast magnetic resonance imaging in Fontan patients

OBJECTIVE

This study compares in vivo pulmonary blood flow patterns and shear stresses in patients with either the direct atrium-pulmonary artery connection or the bicaval tunnel connection of the Fontan procedure to those in normal volunteers. Comparisons were made with the use of three-dimensional phase contrast magnetic resonance imaging.

METHODS

Three-dimensional velocities, flows, and pulmonary artery cross-sectional areas were measured in both pulmonary arteries of each subject. Axial, circumferential, and radial shear stresses were calculated with the use of velocities and estimates of viscosity.

RESULTS

The axial velocities were not significantly different between subject groups. However, the flows and cross-sectional areas were higher in the normal group than in the two patient groups in both pulmonary arteries. The group with the bicaval connection had circular swirling in the cross section of both pulmonary arteries, causing higher shear stresses than in the controls. The disorder caused by the connection of the atrium to the pulmonary artery caused an increase in some shear stresses over the controls, but not higher than those found in the group having a bicaval tunnel.

CONCLUSIONS

We found that pulmonary flow was equally reduced compared with normal flow in both patient groups. This reduction in flow can be attributed in part to the reduced size of the pulmonary arteries in both patient groups without change in axial velocity. We also found higher shear stress acting on the wall of the vessels in the patients having a bicaval tunnel, which may alter endothelial function and affect the longevity of the repair.

Right ventricular performance and mass by use of cine MRI late after atrial repair of transposition of the great arteries

BACKGROUND

The long-term adaptation of the right ventricle after atrial repair of transposition of the great arteries (TGA) remains a subject of major concern. Cine magnetic resonance imaging (MRI), with its tomographic capabilities, allows unique quantitative evaluation of both right and left ventricular function and mass. Our purpose was to use MRI and an age-matched normal population to examine the typical late adaptation of the right and left ventricles after atrial repair of TGA.

METHODS AND RESULTS

Cine MRI was used to study ventricular function and mass in 22 patients after atrial repair of TGA. Images were obtained in short-axis sections from base to apex to derive normalized right and left ventricular mass (RVM and LVM, g/m2), interventricular septal mass (IVSM, g/m2), RV and LV end-diastolic volumes (EDV, mL/m2), and ejection fractions (EF). Results 8 to 23 years after repair were compared with analysis of 24 age- and sex-matched normal volunteers and revealed markedly elevated RVM, decreased LVM and IVSM, normal RV size, and only mildly depressed RVEF. Only 1 of 22 patients had clinical RV dysfunction, and this patient had increased RVM.

CONCLUSIONS

Cine MRI allows quantitative evaluation of both RV and LV mass and function late after atrial repair of TGA. Longitudinal studies that include these measurements should prove useful in determining the mechanism of late RV failure in these patients. On the basis of these early data, inadequate hypertrophy does not appear to be the cause of late dysfunction in this patient group.

MRI complements standard assessment of right ventricular function after lung transplantation

BACKGROUND

Changes in right ventricular mass and ejection fraction after single-lung transplantation for pulmonary hypertension are poorly understood.

METHODS

To complement functional data provided by echocardiography, radionuclide ventriculography, and right heart catheterization, magnetic resonance imaging was used to assess right ventricular function in 5 single-lung transplant recipients with preoperative pulmonary hypertension and right ventricular dysfunction (right ventricular ejection fraction, 0.21 +/- 0.09). The right and left ventricular mass, ejection fraction, and mass ratio (left ventricular mass/right ventricular mass) were calculated from the magnetic resonance images.

RESULTS

The mean pulmonary artery pressure fell from 72 +/- 18 to 21 +/- 8 mm Hg after transplantation. At 3 months after transplantation both the left ventricular and right ventricular ejection fractions approached normal values, as shown by both radionuclide ventriculography and magnetic resonance imaging, but the right ventricular mass remained abnormally high with slightly low mass ratios. By 1 year both the left ventricular and right ventricular masses had regressed to normal with near-normal mass ratios.

CONCLUSIONS

Right ventricular performance returns to nearly normal early after transplantation, but the right ventricular mass regresses over a more prolonged time. Cine magnetic resonance imaging provides a noninvasive means of assessing changes in right ventricular function and mass after lung transplantation.

Progression of childhood linear scleroderma to fatal systemic sclerosis

An 8-year-old girl presented with linear scleroderma, no evidence of systemic disease, and a negative antinuclear antibody (ANA) test. Over the next 12 months, she functioned normally. However, over the subsequent 5 months, she developed dyspnea, progressive pulmonary hypertension, a positive ANA test, and died 17 months after presentation. At autopsy, diffuse pulmonary interstitial fibrosis, small pulmonary arterial fibroplasia, tricuspid and mitral valve subendocardial fibrosis, and distal esophageal fibrosis were seen. Contrary to suggestions in the rheumatology literature, childhood linear scleroderma, even when ANA negative at presentation, may progress to fatal systemic sclerosis.

Operative risk factors and durability of repair of coarctation of the aorta in the neonate

The risk factors for the operative mortality and long-term durability of repair after surgical correction of coarctation of the aorta in neonates remain controversial. Between January 1970 and January 1993, 139 patients under 1 month of age underwent repair of coarctation of the aorta. Complex intracardiac defects were present in 59 patients. Another 44 patients had an associated ventricular septal defect. Subclavian artery flap repair was performed in 92 patients; end-to-end anastomosis (38 patients) and patch angioplasty (9 patients) were performed less commonly. The hospital mortality was significantly higher in patients with complex intracardiac defects (9 of 59 patients; 15.2%) than in those with a ventricular septal defect (1 of 44 patients; 2.3%) or with isolated coarctation (none of 36 patients; p = 0.007). Elevated pulmonary artery diastolic pressure (p = 0.041) and complex intracardiac anomalies (p = 0.048) were found to be independent predictors of hospital mortality. The presence of a complex cardiac defect (p < 0.001) was an independent predictor of poor long-term survival. Recurrent stenosis requiring reoperation had occurred or balloon dilation had been necessary in 27.9% of the children at 5 years postoperatively. In patients followed up for at least 5 years, the recurrence-free survival was better in those who had undergone subclavian artery flap repair than in those who had undergone end-to-end repair (p = 0.017). When coarctation of the aorta must be repaired in the neonate, operative mortality and long-term survival are affected by the complexity of associated intracardiac anomalies.(ABSTRACT TRUNCATED AT 250 WORDS)

Pre-operative assessment of ventricular function in patients considered for Fontan procedure

In 1978 Choussat and Fontan established ten criteria, which should be fulfilled to achieve a successful outcome in Fontan operation. Recent data suggest that while some of these ten criteria need not be necessarrily be fulfilled, new criteria should be added. These include 1. good diastolic function, 2. normal or only slightly increased ventricular mass, and 3. absence of systemic outflow obstruction. In addition the morphology of the single ventricle may be important as long-term results in patients with single ventricle of right ventricular morphology may be worse than results in patients with single ventricle of left ventricular morphology. Ventricular size and pump function can be assessed by cardiac catherization, echocardiography or magnetic resonance imaging. Estimation of ejection fraction under stress by nuclear angiography may be indicated. Diastolic function can be examined using Doppler echocardiography or nuclear angiography. Myocardial mass may be assessed by echocardiography or magnetic resonance imaging. Normal reference values for different parameters of systolic and diastolic function are listed in the enclosed tables. Patients scheduled for a Fontan operation should have an ejection fraction less than 50%. Patients with borderline ejection fraction should be examined by echocardiography to determine the end-systolic wall stress, a parameter of ventricular contraction, which is independent of pre- and afterload. As afterload may decrease after a Fontan operation some patients with reduced ejection fraction but normal end-systolic wall stress may still be suitable candidates for Fontan operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic estimation of critical left ventricular size in infants with isolated aortic valve stenosis

With the current trend to performing surgical valvotomy for infantile aortic stenosis without cardiac catheterization, there is a need to develop echocardiographic criteria for adequacy of left ventricular size. The echocardiograms and catheterization data of all 25 infants less than 3 months of age undergoing aortic valvotomy for isolated aortic valve stenosis from September 1980 through July 1990 were reviewed. Significant differences (p less than 0.05) between the survivors and nonsurvivors were noted for age at operation (30 +/- 28 vs. 3 +/- 1.5 days), mitral valve diameter (10.1 +/- 1.7 vs. 7.7 +/- 1.5 mm), left ventricular end-diastolic dimension (18.4 +/- 6.4 vs. 11.4 +/- 3 mm), left atrial dimensions (15.3 +/- 3.8 vs. 10 +/- 2.4 mm), left ventricular cross-sectional area on the parasternal long-axis echocardiogram (4 +/- 1.9 vs. 2 +/- 1.9 cm2) and angiographically determined left ventricular end-diastolic volume (43 +/- 23 vs. 11 +/- 5 ml/m2). There was no difference with respect to patient weight, body surface area, aortic root dimension or left ventricular ejection fraction. Left ventricular cross-sectional area less than 2 cm2 as measured on the parasternal long-axis echocardiogram was found in 5 of 7 nonsurvivors and 0 of 12 survivors, making this a risk factor for perioperative death (p less than 0.05). Left ventricular end-diastolic dimension less than 13 mm was found in 5 of 6 nonsurvivors and 2 of 17 survivors, making this another risk factor for early mortality (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Complete repair of atrioventricular septal defect

We report our experience with 103 consecutive children who underwent repair of complete atrioventricular septal defect between 1971 and 1990. Ninety-one patients were less than 18 months old (mean age, 6.2 months; mean weight, 5.8 kg) and were repaired using deep hypothermia and circulatory arrest. There were 15 perioperative deaths. Twelve patients were older (mean age, 40.2 months; mean weight, 18.9 kg) and were repaired using moderate hypothermia and cardiopulmonary bypass. There were two perioperative deaths. Repairs were performed with the single-patch technique. Four younger patients required repeat repair to control residual mitral regurgitation. Two of the older children required late reoperation to replace one or both atrioventricular valves. Three younger children underwent pulmonary artery banding initially; 1 died after complete repair. Three older children underwent initial pulmonary artery banding; 2 died at definitive repair, and the survivor required pulmonary artery reconstruction, which was repeated subsequently. Since 1977 our policy has been to perform primary definitive repair whenever possible. Two patients died late from unrelated causes. At the most recent follow-up the majority of patients had no or minimal symptoms. We continue to advocate primary definitive repair whenever possible using the single-patch technique in symptomatic patients with complete atrioventricular septal defect.

Unique variant of partial anomalous pulmonary venous connection with intact atrial septum

Partial anomalous pulmonary venous connections (PAPVCs) are rare in association with an intact atrial septum. However, the diagnosis should be considered in patients with otherwise unexplained findings of left-to-right shunt and right heart enlargement. An unusual variant is presented, which we considered unsuitable for operative repair, based on findings at catheterization. Developmental, hemodynamic, and surgical considerations are discussed.

Reappraisal of localized resection for subvalvar aortic stenosis

Between June 1972 and August 1989, we operated on 45 patients with fixed subaortic stenosis. Discrete membranous stenosis was present in 28 patients and tunnel stenosis, in 13. Four patients had subvalvar stenosis complicating double-outlet right ventricle. There were 33 male and 12 female patients. Mean age at operation was 7.1 +/- 4.3 years (range, 6 months to 21 years). Local resection of the fibrous membrane was performed in 26 patients. Local resection was combined with myectomy in 18 patients. Aortoventriculoplasty (modified Konno procedure) was required at operation in 3 patients. There were three perioperative deaths at initial operation and two deaths at the time of reoperation. Follow-up ranges from 1 month to 17 years (average follow-up, 47.0 months). Reoperation for recurrent obstruction has been required in 12 patients (27%), and 3 patients have required a second reoperation. Mild to moderate aortic regurgitation was present in 17 patients. Subaortic stenosis is a spectrum of anatomical derangements ranging from a discrete fibrous membrane to a long, tortuous fibrous tunnel with aortic annulus hypoplasia. Successful removal of a discrete fibrous membrane can be followed later by recurrent stenosis necessitating myectomy or aortoventriculoplasty. Correction of subvalvar aortic stenosis can be followed by recurrent stenosis necessitating reoperation as long as 17 years after the initial procedure.

Normal values for noninvasive estimation of left ventricular contractile state and afterload in children

The outcome and suitability for therapeutic interventions in children with congenital heart disease depend frequently on left ventricular function. Congenital heart disease is characterized by changes in loading conditions, making it difficult to assess ventricular contractility using conventional load-dependent indexes. Two-dimensional and M-mode echocardiography and arterial blood pressure were used to study left ventricular morphometrics and contractility in 44 normal children, aged 2 to 12 years. Left ventricular end-systolic and end-diastolic length, diameter, wall thickness, volume and mass all showed linear increases with body surface area (p less than 0.001 in all). Shortening and ejection fractions, velocity of circumferential fiber shortening, morphometric ratios and endocardial meridional and circumferential stress (mean 46 and 115 g/cm2, respectively) all remained constant. A load-independent measure of the normal resting left ventricular contractile state was determined by relating the rate-corrected velocity of circumferential fiber shortening to end-systolic endocardial meridional and circumferential stress; there was an inverse linear correlation (r = -0.641 and -0.557 respectively, p less than 0.001). These data provide a quantitative basis for assessment of myocardial hypertrophy, afterload and contractile state in childhood.

An outbreak of acute rheumatic fever in Tennessee

From January, 1987, until July, 1988, a significant increase in newly diagnosed cases of acute rheumatic fever was noted at our hospital. In sharp contrast to the 3 cases seen in 1986, 14 cases were diagnosed in 1987 (a significant increase from 1985 to 1986, P = 0.001). In the first 6 months of 1988 an additional 12 new cases were diagnosed (a further significant increase from 1987, P = 0.02). No further cases were diagnosed between July, 1988, and September, 1989. The major clinical manifestations were carditis in 73%, polyarthritis in 58% and chorea in 31%. In 15 of 26 patients an antecedent illness which included pharyngitis was noted; the remainder of patients were asymptomatic. Group A beta-hemolytic streptococci were isolated from 13 of 19 children cultured. Isolates from two patients with acute rheumatic fever were submitted for M typing: one isolate was mucoid M18/T18; the other isolate was a mucoid nontypable strain. The demographic characteristics of the 26 patients agree with classic descriptions in that patients were more likely to be urban, to come from large families and to have low incomes; racial breakdown of the group mirrored the Tennessee pediatric population. These characteristics stand in contrast to reports of recent outbreaks which describe suburban high income patients. These data suggest that practitioners should be again aware of acute rheumatic fever and that aggressive identification and treatment of streptococcal pharyngitis should continue to be a relevant public health concern.

Impact of Fontan operation on left ventricular size and contractility in tricuspid atresia

Left ventricular dimensions and contractility were determined by echocardiography in 33 patients with tricuspid atresia in 1985 and again in 1988. Eight patients remained palliated throughout the 3-year period; neither the left ventricular end-diastolic diameter (153 +/- 15% of normal vs. 157 +/- 19%, p = NS) nor a load-independent index of contractility (rate-corrected velocity of shortening [VCFc]/end-systolic meridional stress [ESSM]) changed. Eleven patients underwent a Fontan operation during the study and were reevaluated at least 6 months after surgery; left ventricular dimension decreased (130 +/- 15% vs. 114 +/- 19%, p less than 0.001), and the contractility index VCFc/ESSM improved (p less than 0.05). Fourteen patients had undergone a Fontan operation 0.9-9.5 years (mean, 4.2 years) before initial examination in 1985. Over the 3-year period, left ventricular dimensions did not change (121 +/- 17% vs. 118 +/- 11%, p = NS), but the contractility index showed significant improvement (p less than 0.01). Eight additional patients were studied just before and after a Fontan operation to examine the early effects of surgery. Left ventricular dimensions decreased from 130 +/- 14% to 100 +/- 13% by 10 days p less than 0.001) with no further change at 2 months. An inappropriate degree of ventricular hypertrophy was observed in only the early postoperative period. Successful Fontan repair results in rapid reduction of left ventricular size, followed by regression of hypertrophy to a normal mass-to-volume ratio. Operating at more favorable dimensions and loading conditions results in an early increase in left ventricular contractility, which further improves in the medium term follow-up.

Absence of left ventricular volume loading in infants with coarctation of the aorta and a large ventricular septal defect

Clinical characteristics and angiographic ventricular volume data were obtained in 25 infants aged 1 to 66 days who presented with coarctation of the aorta, ventricular septal defect and congestive heart failure to determine if left ventricular volume loading was present and if there were hemodynamic or volumetric variables that were predictive of operative mortality in this group. Pulmonary to systemic flow ratio averaged 2.8 +/- 0.8 and right ventricular/left ventricular peak pressure ratio was 0.96 +/- 0.12. Left ventricular end-diastolic volume averaged 116 +/- 49% of normal and was less than the investigators' lower limit of normal in 5 (20%) of 25 patients. In contrast, right ventricular end-diastolic volume, measured in eight patients, averaged 173 +/- 47% of normal and was greater than the investigators' upper limit of normal in seven (88%) of eight. Left ventricular ejection fraction averaged 0.47 +/- 0.17 and was below normal (less than 0.55) in 14 (58%) of 24 patients. Preoperative volume and ejection fraction data did not differ in infants with coarctation plus ventricular septal defect and a similar group of 19 infants with isolated coarctation. Abnormal left ventricular operative volume distensibility was inferred by normal or decreased left ventricular end-diastolic volume and increased left ventricular end-diastolic pressure (greater than 12 mm Hg) in 12 (55%) of 24 patients. Early plus late mortality was related to left ventricular size: 3 of 5 patients with a small left ventricular end-diastolic volume died, compared with only 4 of 20 with a normal or increased volume (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical assessment of ventricular function after surgical treatment of congenital heart defects

The assessment of ventricular function has contributed to the current surgical evaluation and surgical treatment of congenital heart defects, but many issues remain unresolved. The challenge of assessing ventricular function after surgical repair of congenital heart defects includes not only the general problem of distinguishing adverse loading conditions from myocardial failure but also more unique problems of right heart function and developmental differences in ventricular function. The possibility and significance of diastolic dysfunction are essentially unexplored and contingent upon our better understanding of the determinants of diastolic indices. Many of the technologies and methods are currently available and there is the beginning of a move toward better designed clinical trials and analysis of results. The assessment of ventricular function will become increasingly important as surgical techniques are improved and we are left with the more difficult choices between competing approaches.

Ten years' experience with the Senning operation for transposition of the great arteries: physiological results and late follow-up

We report our results in 93 consecutive infants and children who underwent atrial repair of simple transposition of the great arteries using the Senning operation between February 1978 and February 1988. Mean age at operation was 5.6 +/- 6.3 months (range, 1 week to 4 years); 60 were less than 6 months old. There were 65 boys and 28 girls. Operative mortality was 5.4%, and there has been 1 late death. Average follow-up is 45.1 months with 39 followed more than 3 years and 25 followed more than 5 years. Postoperative cardiac catheterization was performed in 43 patients. Right ventricular ejection fraction at rest averaged 0.50 +/- 0.09 and was normal in 26 patients. Response of right ventricular ejection fraction to afterload stress was abnormal in 12 of 14 patients tested. Right ventricular ejection fraction increased normally during exercise in 6 patients, but was abnormal in 15. Mild tricuspid regurgitation was noted in 10 patients. Mild obstruction of the superior vena cava was noted in 4 patients. Baffle leak requiring reoperation occurred in 1 patient. Seventy-two of 80 patients are in sinus rhythm by latest electrocardiogram. Postoperative electrophysiological studies were performed in 34 patients and Holter monitoring was performed in 22. A major arrhythmia occurred in 8 patients: 3 required a pacemaker for junctional rhythm or sinus node dysfunction, 2 have symptomatic or inducible supraventricular tachycardia, 2 have junctional rhythm, and 1 has sick sinus syndrome. Eight additional patients have delayed sinus node recovery time. At last follow-up, 78 children (97.5%) are in New York Heart Association functional class I, and 2 (2.5%) are in class II.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictors of operative mortality in critical valvular aortic stenosis presenting in infancy

Congenital aortic stenosis presenting within the first 6 months of life is a highly lethal anomaly. Although aortic valvotomy has offered excellent palliation in many instances, the operative risk remains substantial. To better understand the factors associated with a poor operative result, the records of all patients less than 6 months of age undergoing aortic valvotomy at our institution from 1972 through 1986 were analyzed. Nineteen patients (58%) (Group I) survived operation; 14 (42%) (Group II) died. The following variables were analyzed in an attempt to define those with prognostic significance: mean pulmonary artery pressure (PAP), left ventricular (LV) peak systolic pressure, LV end-diastolic pressure, peak systolic aortic valve gradient, LV end-diastolic volume (LVEDV), LV ejection fraction, and age at operation. The only variables that were significantly different in the two groups were mean PA (Group I, 29 +/- 3 mm Hg, and Group II, 54 +/- 3 mm Hg; p less than 0.001) and LVEDV (Group I, 50 +/- 8 ml/m2, and Group II, 20 +/- 4 ml/m2; p less than 0.05). No patient with an LVEDV of 20 ml/m2 or less survived operation. We conclude that small LV dimension and elevation of PAP may be predictive of a poor surgical result in patients with severe aortic stenosis presenting in infancy.

Decreased early diastolic function after indomethacin administration in premature infants

The effect of indomethacin on systolic and diastolic cardiac function was assessed in 15 premature infants. Seven infants (group 1) received indomethacin to treat a clinically significant patent ductus arteriosus (PDA), and eight infants (group 2) received indomethacin prophylactically at 24 hours of age because of their high risk for PDA. Diastolic cardiac function was assessed using instantaneous rates of change of left ventricular (LV) cavity dimension, derived from M-mode echocardiography. The maximum velocity of lengthening of the LV cavity dimension, an index of early diastolic function, fell from 63 +/- 19 mm/sec before indomethacin to 48 +/- 16 mm/sec 1 hour after indomethacin in group 1 (P less than 0.01), with the ductus still patent and the LV chamber still dilated, and also decreased in group 2, from 52 +/- 7 mm/sec to 38 +/- 6 mm/sec (P less than 0.01). This index, when normalized for loading conditions, was decreased 1 hour after indomethacin at 12 +/- 2 sec-1 and 12 +/- 1 sec-1 for groups 1 and 2, respectively, compared with values before indomethacin of 15 +/- 3 sec-1 and 15 +/- 2 sec-1. There was no effect of indomethacin on the indices of systolic function. We conclude that indomethacin decreases early diastolic function in premature infants.

Left-ventricular cavity dimensions in children with normal and dilated hearts

Studies were carried out to find how left-ventricular length and length/diameter ratio relate to body size and degree of dilation. By use of M-mode and two-dimensional echocardiography, diastolic cavity long axis (Led), diastolic cavity diameter (Ded), systolic cavity long axis (Les), systolic cavity diameter (Des), fractional L shortening (SFL), and fractional D shortening (SFD) were measured in children, adolescents, and young adults between two and 23 years of age, with body-surface area (BSA) between 0.5 and 2.1 m2 and with a variety of volume loads and SFD values. In normal subjects, Led/Ded was about 1.9. Regardless of age and pathology (in this age range), Led correlated consistently with BSA (Led = 3.9 + 3.2 BSA), indicating that the long axis changes rather little with pathological dilation. A plot of Led/Ded vs BSA/D2ed (in m2/cm2) formed a straight-line relation: Led/Ded = 0.77 + 16.4 BSA/D2ed. Similar relations were found for end-systolic dimensions. End-systolic L/D ratio exceeded end-diastolic L/D ratio to a degree that depended on both end-diastolic L/D ratio and SFD:Les/Des = Led/Ded + (0.22 + 2.67 Led/Ded)(SFD)2. Relations like these may be useful in the interpretation of echocardiographic images. The results suggest that left-ventricular L/D ratio may be influenced by myocardial anisotropy (dominance of hoop over meridional fiber orientation tending to promote prolate shape especially during systole) and external factors that antagonize extension of the long axis.

Effects of postnatal maturation on postrest potentiation in isolated rabbit atria

Ultrastructural changes in cardiac sarcoplasmic reticulum (SR) have been reported during postnatal development of the mammalian heart, but the functional significance of these observations has not been well characterized. Calcium release from SR in intact myocardial preparations was determined by the contractile characteristics of postrest contractions. Isometric tension and the maximum rate of tension development of the first contraction following intervals of electromechanical quiescence (rest) were related to steady-state tension and maximum rate of tension development during contraction at constant frequency (1.0 Hz) in isolated left atrial strips from newborn (1-7 days), immature (14-21 days), and adult (more than 6 months) rabbits. The first postrest contraction was increased as a function of the rest interval rate of tension development, defined as postrest potentiation, in all three age groups and reached a maximum value at rest intervals of more than 20 s. Tension developed by the first contraction following a 60-s rest interval was potentiated less in newborn and immature atria than in adult atria at an extracellular calcium concentration ([Ca]e) of 2.5 mM, an age-related difference most marked in the immature. Ryanodine (5.0 X 10(-9) M), a putative blocker of calcium release from cardiac SR, abolished postrest potentiation providing evidence that calcium release from SR is the predominant determinant of the postrest contraction. Postrest tension in atria from the immature rabbit heart was significantly increased both in absolute terms and relative to steady-state tension following stabilization under conditions which increase intracellular [Ca] [( Ca]i), i.e. increasing [Ca]e, increasing tonicity, or decreasing extracellular sodium concentration ([Na]e).(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial adenosine triphosphate content as a measure of metabolic and functional myocardial protection in children undergoing cardiac operation

In an effort to quantitate the metabolic and functional response to global myocardial ischemia as a prelude to specific interventions to improve myocardial protection in children, the following data were collected. Twenty children (age, 1.16 +/- 0.3 years) underwent repair of congenital intracardiac malformations using aortic cross-clamping and cold potassium cardioplegia (ischemic time, 56.1 +/- 4.5 minutes). Metabolic protection was assessed by measuring the myocardial adenosine triphosphate (ATP) content by microbioluminescence. Before and after ischemia 10-mg myocardial samples were obtained from the left ventricular apex using a Tru-cut biopsy needle. In 15 patients, postoperative ventricular function was measured by radionuclide ventriculography at 72 to 96 hours following operation. Five of 6 patients with a postischemic ATP level less than 40% of control (26.3 +/- 2.8) had a left ventricular ejection fraction (EF) lower than 55% (50.3 +/- 2.3). Seven of 9 patients with an ATP level greater than 40% of the preischemic level (98.0 +/- 14.4) had a normal EF (61.8 +/- 2.9; p less than 0.04). Two other patients with postischemic ATP levels lower than 40% of control died of low cardiac output and had no postoperative ventricular function studies. Thus, of 7 patients with postischemic ATP levels lower than 40% of preischemic levels, 2 died and 5 had depressed left ventricular function. These data support the concept that low postischemic ATP levels correlate with death or poor postoperative ventricular function, and indicate that this variable will be useful to assess future improvements in myocardial protection during pediatric cardiac operations.

Detection of caval obstruction by magnetic resonance imaging after intraatrial repair of transposition of the great arteries

Vena caval obstruction may cause significant morbidity after intraatrial repair of transposition of the great arteries (TGA). Two noninvasive methods of diagnosing vena caval obstruction were compared with cardiac catheterization. Echocardiographically gated magnetic resonance imaging (MRI) and echocardiographic evaluation (2-dimensional saline contrast echocardiography and pulsed Doppler flow measurement) were performed on 15 patients 0.7 to 13.5 years after intraatrial repair of TGA (8 Mustard, 7 Senning). At catheterization, complete superior vena cava or partial caval obstruction (gradient greater than 5 mm Hg from cava to systemic venous atrium) was present in 7 of 15 patients. Superior vena cava obstruction was directly visualized by MRI in both patients with catheterization-proved complete superior vena cava occlusion. A dilated azygous/hemiazygous venous complex (greater than or equal to 5 mm cross-sectional diameter) was seen by MRI in 5 of 7 patients with complex or partial vena caval obstruction and in no patient without vena caval obstruction. MRI showed superior vena caval dilatation (ratio of superior vena caval diameter to aortic diameter greater than 1.45) in 3 of 5 patients with partial vena caval obstruction and in 0 of 8 without vena caval obstruction. Direct visualization of narrowing within the atrium was unreliable for any MRI plane because of the 3-dimensional nature of the intraatrial baffle. Two-dimensional saline contrast echocardiography, successfully performed in 12 of 15 patients, detected complete superior vena caval obstruction only in the 2 patients with catheterization-proved complete superior vena cava occlusion. Contrast echocardiography failed to identify any of the 5 patients with partial vena caval obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical intervention in neonates with critical pulmonary stenosis

The surgical experience with 18 consecutive neonates with critical pulmonary stenosis (PS) and intact ventricular septum was reviewed. All patients had cardiac catheterization with calculation of right ventricular volume. Group A patients (N = 8) had a small right ventricular end-diastolic volume (RVEDV less than 72% of predicted). Group B patients (N = 10) had a normal or enlarged RVEDV. All patients had a closed pulmonary valvotomy. Five Group A patients required a systemic-pulmonary shunt or prostaglandin (PGE1) after operation; one patient died. Nine Group B patients did well after valvotomy; one moribund patient died after valvotomy and shunt. Six of 16 survivors required reoperation: valvectomy in four patients and shunt takedown in two patients. Four of the six patients who had reoperation also had a transannular patch. There was one unrelated late death. All long-term survivors are asymptomatic. Recatheterization in four patients with a small right ventricle (RV) documented significant RV growth. In conclusion, most neonates with critical PS can be managed with closed valvotomy. Patients with a small RV may require PGE1 or a shunt after operation for persistent hypoxemia. Some patients with a small RV will have significant RV growth after valvotomy.

Altered early left ventricular diastolic cardiac function in the premature infant

Developmental changes in diastolic ventricular function were assessed in 31 premature infants and in 10 normal-term infants. They were studied during the first 72 hours of life using instantaneous rates of change of left ventricular (LV) cavity dimension, derived from M-mode echocardiography. Maximal velocity of lengthening of the LV cavity was significantly lower in premature infants (38 +/- 7 mm/s) than in term infants (88 +/- 15 mm/s). This variable increased with increasing maturity over the 4 gestational age groups evaluated (r = 0.87). This index normalized for instantaneous LV dimension was lower in the most immature infants (4.5 +/- 1 s-1) than in term infants (6.8 +/- 2 s-1). Eight of the premature infants were studied serially at 1, 3 and 7 days of age. Maximal velocity of lengthening divided by stroke dimension improved from 12.9 +/- 2 s-1 at 1 day of age to 16.5 +/- 3 s-1 at 7 days. These results suggest depressed early diastolic function in premature infants.

Left ventricular wall stress and contractile function in transposition of the great arteries after the Rastelli operation

Left ventricular wall stress and contractile function were determined by echocardiographic methods in 11 patients studied 0.7 to 13.8 years (mean +/- standard error of the mean = 5.6 +/- 1.2 years) after undergoing the Rastelli operation for transposition of the great arteries associated with ventricular septal defect and left ventricular outflow tract obstruction. Age at operation ranged from 4.6 to 11.3 years (mean +/- standard error of the mean = 7.4 +/- 0.7 years). Data were compared with data of 24 normal subjects of similar age and heart rate. Left ventricular end-diastolic dimension and end-diastolic volume were significantly higher than normal, averaging 134% +/- 8% of normal dimension (p less than 0.004) and 106 +/- 13 ml/m2 versus a normal volume of 60 +/- 3 ml/m2) (p less than 0.007). In addition left ventricular wall mass was 215 +/- 40 gm/m2 versus a normal value of 72 + 6 gm/m2 (p less than 0.004). Both meridional and circumferential end-systolic and peak systolic stress values were not significantly different between normal subjects and Rastelli patients. Estimates of ventricular pump function including shortening fraction, rate-corrected velocity of circumferential fiber shortening, and ejection fraction were all depressed when compared with normal values. Velocity of fiber shortening, evaluated as a function of end-systolic stress, demonstrated abnormal contractile function in eight of 11 (73%) patients. These data indicate that left ventricular function is usually abnormal and residual left ventricular dilation and wall hypertrophy remain despite successful use of the Rastelli operation for repair in patients with transposition of the great arteries, ventricular septal defect, and left ventricular outflow tract obstruction.

Surgical treatment of pediatric cardiac arrhythmia

The combination of improved diagnostic techniques, new and potent antiarrhythmia agents, and progress in antiarrhythmia surgical procedures has resulted in successful management of complex cardiac arrhythmia in children. The kinds of arrhythmia that can be considered for possible surgical intervention share several features. Each produces symptoms and usually is hemodynamically compromising. Each requires extensive preoperative and intraoperative electrophysiologic evaluation to establish the mechanism, response to drugs, and suitability for surgery. Although reports of surgical arrhythmia treatment have been limited in children, with increasing success the indications for such treatment may become less stringent. Our recommendations are shown in the Table. In general, patients intolerant of or unresponsive to medical treatment for symptomatic arrhythmia (tachycardia or bradycardia), should be considered candidates for surgical antiarrhythmia procedures. These patients should be referred for testing to cardiac centers staffed by pediatric cardiac electrophysiologists and surgeons experienced in arrhythmia diagnosis and ablation. Careful evaluation can identify those patients in whom surgical approaches are most appropriate. At present, surgical operations for selected, serious pediatric cardiac arrhythmias offer definitive and possibly curative treatment, and may be preferable to inadequate, poorly tolerated, or long-term medical therapy.

Hemodynamic effects of hydralazine in infants with idiopathic dilated cardiomyopathy and congestive heart failure

We evaluated the acute hemodynamic responses to hydralazine during cardiac catheterization in 13 infants with idiopathic dilated cardiomyopathy. Ages ranged from 2 to 13 months (6.7 +/- 4.0 months, mean +/- SD). Each infant had congestive heart failure and angiographic evidence of markedly depressed left ventricular ejection fraction (0.24 +/- 0.11; normal = 0.58-0.78) with left ventricular dilation (left ventricular end-diastolic volume = 349 +/- 125% of normal). Hydralazine (0.5 to 1.0 mg/kg administered intravenously) acutely decreased systemic arteriolar resistance from 21.1 +/- 3.3 to 12.0 +/- 2.7 U/m2 (p less than 0.001). This 41 +/- 14% decrease in systemic resistance was accompanied by a 45 +/- 16% increase in cardiac index (3.24 +/- 0.53 to 4.71 +/- 0.99 L/min/m2; p less than 0.001). Mean arterial blood pressure declined from 70 +/- 8 to 60 +/- 11 mm Hg (p less than 0.001). Hydralazine also increased heart rate (122 +/- 19 to 138 +/- 18 bpm; p less than 0.001), but this increase did not account entirely for the change in cardiac index as evidenced by a rise in stroke volume index (26.9 +/- 4.9 to 34.5 +/- 7.5 ml/beat/m2; p less than 0.001). Pulmonary arteriolar resistance and pulmonary capillary wedge pressure fell slightly in response to hydralazine. Subsequently, oral hydralazine was included in the treatment regimen of 10 infants followed for 3 to 38 months (mean = 15 months). Of these, eight demonstrated sustained clinical improvement. We conclude that hydralazine may be a beneficial adjunct to the management of congestive heart failure in young infants with a dilated cardiomyopathy.

Ventricular pump performance in patients with obstructed right ventricular-pulmonary artery conduits

Postoperative data were obtained from 18 patients with partially obstructed right ventricular (RV) to pulmonary artery (PA) conduits, who were studied 1 to 9 years following a Rastelli operation. Age at operation was 1 to 8 months in seven patients (group I: infant group) and 2 to 9 years in the remaining 11 patients (group II: childhood group). The diagnosis was pulmonary atresia in eight patients, truncus arteriosus in seven, and transposition of the great arteries with ventricular septal defect and pulmonary stenosis in three. Porcine-valved conduits were inserted in 17 patients and an aortic homograft in one. All but seven patients were free of symptoms at the time of postoperative study. Neither peak RV pressures nor RV to PA gradients were different between groups. RV ejection fraction (EF) was decreased in group II (0.43 +/- 0.11) but was normal (0.60 +/- 0.10) in group I. In addition, there was a significant inverse relationship between RVEF and age at repair (r = 0.714; p less than 0.005). RV end-diastolic volume (EDV) was normal or increased in all patients and did not differ between the two groups. Left ventricular (LV) ejection fraction was also decreased in the older group (0.56 +/- 0.10 vs 0.68 +/- 0.08; p less than 0.05), and there was a decrease in RVEF and/or LVEF from pre- to postoperative studies in one of six group I patients compared with four of five group II patients.(ABSTRACT TRUNCATED AT 250 WORDS)