Hemodynamic effects of dobutamine in children.

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

Management of symptomatic infants with anomalous origin of the left coronary artery from the pulmonary artery

There is disagreement concerning the optimal management of infants with congestive heart failure due to anomalous origin of the left coronary artery from the pulmonary artery. This report describes treatment in 23 such patients who had congestive heart failure before age 6 months. Eight patients had an operation in the 1st year of life and only two (25 percent) of these patients survived. Fifteen patients received initial medical treatment, and operation was delayed until an average age of 7.5 years; 13 (87 percent) of these patients survived. The two patients who survived early operation are still alive at an average age of 2.5 years. The 13 survivors in the medical group are still alive at an average age of 14.5 years. The age at onset and the severity of congestive heart failure were similar in the two groups. The frequency of the electrocardiographic pattern of myocardial infarction was similar in both groups. The radiographic cardiothoracic ratio was 0.74 in the surgical and 0.66 in the medical group. In 10 patients the left ventricular ejection fraction was less than 20 percent in the 1st year of life. In 7 of these 10 patients operation was performed before age 1 year and 2 (28 percent) survived; of the 3 patients treated medically, 1 (33 percent) survived.The outcome of surgical or medical treatment of the infant with anomalous origin of the left coronary artery from the pulmonary artery may be biased by patient selection. In the infants with depressed left ventricular function, the results of surgical and medical treatment are equally disappointing. Because coronary arterial surgery in the 1st year of life in infants with severely depressed myocardial function has an extremely high mortality rate (75 percent) and because many symptomatic infants with anomalous origin of the left coronary artery from the pulmonary artery can be treated medically and survive, we recommend delay of operative intervention until at least age 18 months.     

Congenital complete atrioventricular block: Clinical and electrophysiologic predictors of need for pacemaker insertion

Because an initial Adams-Stokes attack in the patient with congenital complete atrioventricular (A-V) block may sometimes prove fatal, there is a need to be able to identify the patient at great risk of having such attacks. Twenty-four children with congenital complete A-V block were followed up for 1 to 19 years to determine the efficacy of current methods of predicting risk for Adams-Stokes syncope and the usefulness of pacemaker therapy in relieving symptoms. The heart rate at rest, configuration of surface electrocardiographic complexes, data obtained during intracardiac electrophysiologic study and response to graded treadmill exercise testing were compared in children with and without syncope. One or more Adams-Stokes episodes were experienced by eight children, one of whom died. Only a persistent heart rate at rest of 50 beats/min or less demonstrated any significant (probability [p] < 0.01) correlation with the incidence of syncope. Intracardiac electrophysiologic study was of little benefit because the site of block did not correlate with syncope. Although the increase in heart rate during treadmill exercise testing showed no correlation with prevalence of syncope or location of block, exercise-induced ventricular ectopic beats may have predictive value in older children and young adults.

Ventricular pacemakers were implanted in 10 children. Each child was asymptomatic over a 1 to 10 year follow-up period. Because extreme bradycardia may contribute to the prevalence of Adams-Stokes attacks in children with congenital complete A-V block, careful evaluation of heart rate at rest may be an effective means of differentiating patients at risk of syncope. Pacemaker therapy is a feasible and effective method of treatment in young children and relieves symptoms.     

Effects of verapamil on supraventricular tachycardia in children

Thirteen patients, aged 6 weeks to 16 years, with uncontrolled recurrent Supraventricular tachycardia were given intravenous verapamil in an attempt to abolish an episode of Supraventricular tachycardia. All patients had had intracardiac electrophysiologic studies to define the mechanism of their tachycardia. In seven patients conversion to sinus rhythm occurred after administration of verapamil: Five of the seven had atrioventricular (A-V) nodal reentry as the mechanism of their supraventricular tachycardia; the other two had reentrant tachycardia involving an accessory pathway. Verapamil was effective in abolishing the Supraventricular tachycardia in these patients, probably by prolonging the A-V nodal refractory period and conduction, thus breaking the reentrant circuit. In six patients there was no conversion to sinus rhythm: Four of the six had automatic atrial ectopic tachycardia and two had automatic junctional ectopic tachycardia. Among the four patients with automatic atrial ectopic tachycardia, a junctional escape rhythm developed in one, and second degree A-V block developed in the others. The two patients with junctional ectopic tachycardia had severe symptomatic arterial hypotension after verapamil and required resuscitation with intravenous calcium chloride. In spite of the good response to intravenous verapamil in the seven patients with reentrant tachycardia, only four of the seven could be maintained successfully on long-term oral therapy. The patients who experienced conversion to sinus rhythm with an intravenous bolus dose of verapamil but in whom Supraventricular tachycardia could still be induced with programmed stimulation could not be maintained successfully on oral therapy.It is concluded that verapamil is an effective antiarrhythmic agent that can (1) abolish the acute episode of Supraventricular tachycardia only in cases due to reentrant mechanisms, and (2) be used as an oral medication to prevent recurrences of supraventricular tachycardia in patients in whom the arrhythmia cannot be induced with programmed stimulation after intravenous doses of the drug.     

Surgical treatment of supraventricular tachycardia in infants and children

The technique, indications and results of surgical division of accessory atrioventricular connections in 10 infants and children with drug-resistant Supraventricular tachycardia are described. The patients ranged in age from 6 months to 15 years. Four patients had associated congenital heart disease. Division of accessory connections were performed on free wall pathways in nine patients (seven right atrial, two left atrial) and on a septal pathway in one patient. Four patients had both anterograde and retrograde conduction over the accessory connection (manifest Wolff-Parkinson-White conduction) whereas six had only retrograde conduction (concealed Wolff-Parkinson-White conduction). The manifest Wolff-Parkinson-White conduction was abolished by surgical division in all four patients. In 8 of the 10 patients the procedure stopped the attacks of paroxysmal supraventricular tachycardia for follow-up periods ranging from 9 months to 3 $\text{1}\text{2}$ years; no patient receives medication to date.     

Electrophysiologic effect of digitalis on sinoatrial nodal function in children

Despite the prevalence of digitalis usage in children, the electrophysiologic effects of digitalis on sinoatrial (S-A) nodal function is unknown in this age group. The purpose of this study was to determine the effect of digitalis on sinoatrial conduction time as well as on S-A nodal automaticity. Ten subjects (mean age 10.5 years) underwent electrophysiologic assessment of S-A nodal function before and 30 minutes after administration of ouabain (0.01 mg/kg). Total S-A conduction time increased in each subject and the mean value after ouabain (182 msec ± 13 standard errors of the mean [SEM]) was significantly higher (P < 0.01) than before (149 msec ± 11). The sinus cycle length was variable after ouabain (P > 0.1). The corrected sinus nodal recovery time also was variable (P > 0.1), decreasing substantially in three subjects. Mechanisms of the effect of digitalis on the S-A node and atrium are proposed and discussed.

It is concluded that digitalis prolongs the S-A conduction time in children with normal S-A nodal function. By prolonging the S-A conduction time, digitalis may artifactually shorten corrected S-A nodal recovery time in some patients.     

Echocardiographic evaluation of left ventricular function in children with congestive cardiomyopathy

Echocardiography was used to study left ventricular function in 37 children with congestive cardiomyopathy. Left atrial and left ventricular diameters were approximately 1.5 times that predicted by body weight, whereas systolic decrease in left ventricular diameter (shortening fraction) and increase in posterior wall thickness were half that of normal children. The ratio of left ventricular preejection period to ejection time was increased in 25 patients and normal in 10. The mean velocity of circumferential fiber shortening was decreased in 30 of 34 patients and averaged 52 percent of that predicted by heart rate.

The shortening fraction was higher in the 12 patients who were asymptomatic at the time of study than in the 25 who had symptoms of congestive heart failure (19.6 ± 2.4 standard error of the mean versus 14.6 ± 1.2) (P < 0.05). In 11 patients whose condition improved after therapy with digoxin and diuretic drugs, serial echocardiograms showed significant increases in shortening fraction and posterior wall thickening and decreases in left atrial diameter and the ratio of preejection period to ejection time. However, one or more indexes of left ventricular function remained abnormal, despite the resolution of symptoms and a return of heart size to normal as judged from the chest roentgenogram.     

The surgical decision in tetralogy of Fallot: weighing risks and benefits with decision analysis

The preferred management of the symptomatic infant less than 2 years of age with tetralogy of Fallot remains unsettled. In this study decision analysis was used to assess the risks and benefits of three courses of action: (1) primary intracardiac repair; (2) palliative operation in infancy and delayed intracardiac repair; and (3) treatment with propranolol in infancy and delayed intracardiac repair. For each action the likelihood was determined of three possible outcomes for the patient: (1) death, (2) poor surgical result, or (3) good surgical result. Each outcome was associated with an estimated life expectancy. The best action was defined as that resulting in the longest life expectancy. With use of previously reported data and those from experience at one institution, a range of probabilities was estimated for death before operation, surgical mortality, success of propranolol treatment and hemodynamic result of operation. The choice of action was affected most by the mortality of primary intracardiac repair and the likelihood of a good hemodynamic result from intracardiac repair. Less important factors were the outcome of a palliative operation and the likelihood of success with propranolol therapy. It was found that in the institution studied if the mortality rate of primary intracardiac repair is 10 percent or less, intracardiac repair should be performed; otherwise propranolol treatment, which allows delay in intracardiac repair, should be selected. Both alternatives are preferable to palliative operation. With decision analysis, the clinician can use probabilities and life expectancy appropriate to a given clinical setting in determining the best management for the infant with tetralogy of Fallot.     

Elective mapping and surgical division of the bundle of Kent in a patient with Ebstein's anomaly who required tricuspid valve replacement

A 14 year old girl with Ebstein's anomaly and Wolff-Parkinson-White syndrome without supraventricular tachycardia underwent closure of an atrial septal defect and tricuspid valve commissurotomy. Her postoperative course was complicated by her first episodes of recurrent debilitating paroxysmal supraventricular tachycardia. Severe tricuspid insufficiency with low cardiac output necessitated a repeat intracardiac operation. At reoperation the patient underwent successful tricuspid valve replacement with concomitent cardiac mapping and division of the bundle of Kent. In patients with heart disease requiring intracardiac repair who also have Wolff-Parkinson-White syndrome, elective surgical division of the anomalous bundle is recommended whether or not preoperative attacks of tachycardia have occurred.     

Ventricular septal defect in infancy: Detection with two dimensional echocardiography

To determine the sensitivity and specificity of two dimensional echocardiography in detecting ventricular septal defect two dimensional echocardiograms were performed on 53 infants under 1 year of age. The diagnosis of ventricular septal defect was confirmed by cardiac catheterization in 27 patients; an intact ventricular septum was confirmed by catheterization in 18 and clinically in 8. Using a 35 ° mechanical sector scanner with a 3.5 megahertz transducer, we imaged the ventricular septum in the long axis and in a four chamber view (apical or subcostal, or both). Images were recorded on videotape and reviewed independently by two observers unaware of the diagnosis. Interobserver agreement was 94 percent. Among the 27 patients with a ventricular septal defect, the lesion was correctly identified in 20 (74 percent) and was undetected in 7 (3 of whom had a defect less than 4 mm in diameter, as determined by angiography). No defect less than 4 mm in diameter was detected. Among the 26 patients with an intact septum, a defect was correctly excluded in 23 (88 percent); a false positive diagnosis was made in 3. The apical and subcostal views demonstrated the greatest number of defects (20 of 20), but also gave the highest number of false positive diagnoses (3 of 3). The long axis view was helpful when positive, but showed only 9 of 20 of the defects.In this study, two dimensional echocardiography detected approximately three fourths of ventricular septal defects large enough to warrant cardiac catheterization in the 1st year of life. False positive diagnoses were related to dropout of echoes in the membranous septum when imaged in the four chamber views.     

Relation of the echocardiographic estimate of left ventricular size to mortality in infants with severe left ventricular outflow obstruction

The relation of left ventricular size, as estimated with echocardiography, to mortality was evaluated in three groups of infants with severe left ventricular outflow obstruction. Group I consisted of 17 patients with combined aortic and mitral stenosis or atresia associated with definite hypoplasia of the left ventricle. Group II consisted of eight patients with the primary diagnosis of severe aortic stenosis. Group III consisted of 12 patients with severe coarctation of the aorta. The left ventricular enddiastolic dimension measured with M mode echocardiography and the cross-sectional area of the left ventricular cavity as seen in the parasternal long axis view of the two dimensional echocardiogram were used as indexes of left ventricular volume.All patients with symptomatic outflow obstruction and a left ventricular end-diastolic dimension of less than 13 mm died in infancy. However, five patients with a hypoplastic left ventricle proved at angiography or at autopsy, or both, were found to have a ventricular end-diastolic dimension of 13 mm or greater. Two dimensional echocardiography showed that the left ventricle in these patients was foreshortened and spherical in shape. The cross-sectional area of the left ventricle of each patient in group I was less than 1.6 cm². This was below the range of cross-sectional areas found in a group of normal infants (1.8 to 3.5 cm² ± 2 standard deviations about the mean). Three patients in groups II and III had a slightly reduced left ventricular area (1.7 cm²) and none of these patients survived infancy.Measurement of the cross-sectional area of the left ventricle is a useful method of determining left ventricular size in infants suspected of having the hypoplastic left ventricle syndrome. Patients who have reduced left ventricular volume as assessed by this technique are at very great risk even if surgical relief of the outflow obstruction is attempted.     

Long-term follow-up of patients with malformations for which definitive surgical repair has been available for 25 years or more

The results of long-term follow-up studies of patients with five common congenital heart defects are reviewed. The lesions included are ventricular septal defect, atrial septal defect, patent ductus arteriosus, pulmonary stenosis and coarctation of the aorta. A definitive, rather than palliative, operation has been available for each of these lesions for more than 25 years. Therefore many patients who have undergone operation for one of these lesions are now reaching adulthood.Although most of these postoperative patients live a normal life, many have residuae or sequelae that require close observation or treatment. Other persistent abnormalities of the physical examination, electrocardiogram and chest radiogram are obvious but call for no precaution or treatment. We have drawn on our own experience and the published experience of others to identify those findings and historical factors that best reflect the long-term prognosis of these patients. In addition, recommendations concerning the need for continued prophylaxis against infective endocarditis, and the problems of insurability and employability of these postoperative patients are discussed.     

Stress-induced ventricular arrhythmia after repair of tetralogy of fallot

The combination of ventricular arrhythmias found on routine electrocardiography at rest and elevated right ventricular pressures may be associated with sudden death in patients after repair of tetralogy of Fallot. In this study data were reviewed from 104 patients who underwent treadmill exercise testing with a modified Bruce protocol at a mean age of 13.8 years, an average of 7 years after repair of tetralogy of Fallot. The frequency and form of ventricular arrhythmias as manifested in an electrocardiogram at rest as well as before, during and after treadmill exercise tests were tabulated for each patient. Cardiac catheterizatlon was performed within 1 week of the treadmill test in 82 of the 104 patients and the right ventricular systolic pressure, right ventricular end-diastolic pressure, pulmonary arterial systolic pressure and pulmonary to systemic flow ($\text{Qp}\text{Qs}$) ratio were compared in patients with and without ventricular arrhythmias. In 15 (14 percent) of the 104 patients, ventricular arrhythmia was evident in the electrocardiogram at rest and in 31 (30 percent) it was induced by treadmill exercise; 5 of the 15 with arrhythmia at rest had no arrhythmia during exercise. Compared with the remaining 73 patients, the 31 patients who had ventricular arrhythmias during treadmill testing (1) were older (16.2 versus 12.8 years, p < 0.01, t test) and were tested at a longer interval after repair of tetralogy of Fallot, (2) had greater right ventricular systolic pressure (52.7 versus 41.3 mm Hg, p < 0.005), (3) had greater right ventricular end-diastolic pressure (8.0 versus 6.1 mm Hg, p < 0.001), and (4) had no difference in pulmonary arterial systolic pressure or $\text{Qp}\text{Qs}$ ratio. Uniform premature ventricular complexes were found in 28 patients, multiform premature ventricular complexes in two and ventricular tachycardia in one. Patients whose ventricular arrhythmia appeared with exercise had similar hemodynamic findings to-those whose arrhythmia disappeared with exercise. Two patients, each with elevated right ventricular systolic pressure and multiform premature ventricular complexes, had cardiac arrest at home.It is concluded that (1) treadmill exercise testing is a sensitive method for detecting ventricular arrhythmia in patients after repair of tetralogy of Fallot; (2) ventricular arrhythmia during treadmill exercise is related to abnormal hemodynamic status; (3) multiform premature ventricular complexes, couplets or ventricular tachycardia with exercise testing are highly associated with abnormal hemodynamic status and sudden death; (4) suppression of ventricular arrhythmia with exercise is neither the characteristic nor necessarily the benign response in these patients; and (5) ventricular arrhythmia may be a late developing phenomenon and may increase with longer postoperative intervals. Patients after repair of tetralogy of Fallot should be treated for ventricular arrhythmia detected in the electrocardiogram at rest or during treadmill exercise testing.     

Intracardiac undifferentiated sarcoma in infancy

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

Prevention of sudden death after repair of tetralogy of Fallot: treatment of ventricular arrhythmias

The majority of sudden deaths after repair of tetralogy of Fallot have been presumed to be due to ventricular arrhythmia; however, it remains to be demonstrated that antiarrhythmic medication reduces the incidence of sudden death. Since 1978, ventricular arrhythmias have been treated aggressively; these include any ventricular arrhythmia on routine electrocardiogram and more than 10 uniform premature ventricular complexes per hour on 24 hour electrocardiogram. A review was undertaken of 488 patients followed up for more than 1 month after repair of tetralogy of Fallot (mean follow-up time 6.1 years); 13.5% had ventricular arrhythmia on routine electrocardiogram. Ventricular arrhythmia appeared from 2 months to 21 years postoperatively (mean 7.3 years). Ventricular arrhythmias were significantly (p less than 0.01) related to: longer follow-up duration, older age at follow-up, older age at operation and higher postoperative right ventricular systolic and end-diastolic pressures. Ventricular arrhythmia on routine electrocardiogram occurred in 100% of those who later died suddenly compared with 12% of those who did not die (p less than 0.01). Treatment for ventricular arrhythmia was given to 46 patients and considered "successful" if there were fewer than 10 uniform premature ventricular complexes per hour on 24 hour electrocardiogram. A successful drug was found in 44 of the 46: 30 of 34 given phenytoin, 6 of 9 given propranolol, 1 of 7 given quinidine, 1 of 2 given disopyramide, 8 of 9 given mexiletine and 4 of 5 given amiodarone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Resolution and accuracy in two dimensional echocardiography

The resolution and accuracy of commercially available two dimensional echocardiographic systems were tested by Imaging two types of in vitro test objects. One consisted of a series of fine parallel threads spaced at known intervals and the other was a tissue phantom in which a series of holes of known size had been cut. The echocardiographic systems tested included a mechanical single element sector scanner, a three element rotary sector scanner and a phased array system. Azlmuthal resolution, lateral resolution and accuracy of horizontal distance measurements were assessed at depths of 2 and 6 cm.For each system, azimuthal resolution was better than lateral resolution, especially when assessed with use of the parallel threads. When the tissue phantom was imaged, the best resolution (2 mm in azimuthal and lateral directions) was obtained with the highest frequency transducer tested (3.5 MHz). The apparent size of a tissue defect was sensitive to gain settings, especially at a depth of 2 cm with lower frequency transducers; at a depth of 6 cm, echographic measurements of defect size were accurate to within 2.5 mm. Recent applications of two dimensional echocardiography require resolution near the apparent limits of current equipment. It Is recommended that the highest frequency transducer and lowest possible gain settings be used in these situations.     

Propranolol: the preferred palliation for tetralogy of Fallot

The records of 35 infants with tetralogy of Fallot who received propranolol as palliative treatment to prevent hypoxemic spells were reviewed to examine the effectiveness and safety of this treatment. Propranolol was successful in eliminating spells for at least 3 months in 28 (80 percent) of the patients. Patients in whom the drug failed received a significantly smaller daily dose (1.2 versus 2.6 mg/kg, p <0.01), and were significantly younger when treatment with the drug was initiated (6.1 versus 11.3 months, p <0.05). Further data analysis revealed that drug dose, rather than patient age, was the more significant factor.Cineangiograms of all patients were reviewed to determine if drug success or failure could be related to anatomy of the right ventricular infundibulum, main pulmonary artery or branch pulmonary arteries. There were no significant differences except that the diameter of the proximal right pulmonary artery was smaller in patients in whom treatment with propranolol failed but, even in this measurement, there was overlap between the two groups.Patients in whom propranolol therapy was successful had a delay in operation by a mean of 13.1 months. The only toxic effect was congestive heart failure, which occurred in one patient at a dose of 4.0 mg/kg per day. Intracardiac repair was performed in 16 patients who were receiving propranolol, which was administered up to the morning of operation. There were two operative deaths, neither related to the use of propranolol. It is concluded that (1) propranolol was effective in preventing hypoxemic spells in 80 percent of infants with tetralogy of Fallot. (2) Its effectiveness might have been greater had larger doses been administered. (3) When effective, propranolol delayed surgical intervention by an average of 13 months. (4) Propranolol did not affect surgical mortality of intracardiac repair. Treatment with propranolol (2 to 6 mg/kg per day) is recommended for all small infants with hypoxemic spells due to tetralogy of Fallot.