New approaches to treatment of incessant ventricular tachycardia in the very young

Operative techniques in association with arrhythmia surgery in patients with congenital heart disease

Arrhythmia surgery in patients with congenital disease is challenged by the range of anatomic variants, arrhythmia types, and intramyocardial scar location. Experimental and clinical studies have elucidated the mechanisms of arrhythmias for accessory connections, atrial fibrillation, atrial reentry tachycardia, nodal reentry tachycardia, focal or automatic atrial tachycardia, and ventricular tachycardia. The surgical and transcatheter possibilities are numerous, and the congenital heart surgeon should have a comprehensive understanding of all arrhythmia types and potential methods of ablation. The purpose of this article is to introduce resternotomy techniques for safe mediastinal reentry and to review operative techniques of arrhythmia surgery in association with congenital heart disease.

Electrocardiographic manifestations: pediatric ECG

Interpretation of pediatric electrocardiograms (ECGs) can be challenging for the Emergency Physician. Part of this difficulty arises from the fact that the normal ECG findings, including rate, rhythm, axis, intervals and morphology, change from the neonatal period through infancy, childhood, and adolescence. These changes occur as a result of the maturation of the myocardium and cardiovascular system with age. Along with these changes, up to 20% of pediatric ECGs obtained in the acute setting may have clinically significant abnormal findings. This article will discuss the approach to the interpretation of ECGs in children, the age-related findings and alterations on the normal pediatric ECG, and those ECG abnormalities associated with pediatric cardiac diseases, including the variety of congenital heart diseases seen in children.

Perinatal arrhythmias: diagnosis and management

The final common pathway to death in all of us is an arrhythmia, yet we still know far too little about the contribution of conduction abnormalities and arrhythmias to the compromised states of the human fetus. At no other time in the human life cycle is the human being at more risk of unexplained and unexpected death than during the prenatal period. The risk of sudden death from 20-40 weeks gestation is 6-12 deaths/1000 fetuses/year. This is equal to, and in some ethnic groups HIGHER than, the risk of death in the adult population with known coronary artery disease over the same time frame (6-12 deaths/1000 patients/year). Because only a small percentage of the United States population is pregnant each year, because fetal demise is not often acknowledged through public displays such as funerals, and finally because fetal death is culturally accepted to a much greater extent than it should be, this critically important area of women's healthcare has not had the technological advances that have been seen in adult cardiac intensive care and other areas of medicine. Fetal cardiac deaths may be preventable and the diseases that lead to these deaths are often treatable, especially if the sophistication of our modern ICU's could somehow be translated to the prenatal monitoring arena. This review article will outline recent advances in evaluating fetal electrophysiology, helping the perinatologist to better understand the nuances of fetal arrhythmias.

Outcome of newborns with asymptomatic monomorphic ventricular arrhythmia

BACKGROUND

Frequent premature ventricular contractions (PVCs), couplets (CPLTs) and episodes of ventricular tachycardia are extremely rare in the neonatal population. Limited information is available with regard to clinical relevance and outcome.

OBJECTIVES

To evaluate the clinical characteristics and outcomes of a group of newborns with ventricular arrhythmias without heart disease.

PATIENTS AND DESIGN

Between January 2000 and January 2003, 16 newborns with ventricular arrhythmias in the absence of heart disease were studied. The newborns were divided into three groups: PVC group (n = 8), CPLT group (n = 4) and ventricular tachycardia group (n = 4). All patients underwent physical examination, electrocardiography, Holter monitoring and echocardiography at diagnosis and at follow-up (1, 3, 6 and 12 months, and yearly thereafter).

RESULTS

Mean (standard deviation, SD) age of the patients was 3 (1.19) days in the PVC group, 3.25 (0.95) days in the CPLT group and 6.5 (9.1) days in the ventricular tachycardia group. Median follow-up was 36 months (range 24-48 months). PVCs disappeared during follow-up in all the neonates, in the PVC group, at a mean (SD) age of 2.1 (1.24) months; in the CPLT group, couplets disappeared at a mean (SD) age of 6.5 (1) months. All patients with ventricular tachycardia were treated; ventricular tachycardia disappeared at a mean (SD) age of 1.7 (0.9) months. Neither death nor complications occurred.

CONCLUSIONS

Ventricular arrhythmias in newborns without heart disease have a good long-term prognosis. Frequent PVCs and CPLTs do not require treatment. Sustained ventricular tachycardia or high-rate ventricular tachycardia must be treated, but the prognosis is generally favourable.

Ventricular tachycardia in a neonate with prenatally diagnosed cardiac tumors: a case with tuberous sclerosis

We report a patient with prenatally diagnosed tuberous sclerosis. Fetal ultrasonography demonstrated multiple cardiac tumors and arrhythmia. After birth, because of frequent supraventricular extrasystoles, the infant was admitted to the neonatal intensive care unit. Findings on 24-hour ambulatory electrocardiogram (ECG) showed frequent supraventricular tachycardia and ventricular tachycardia with four beats as the longest run. At the age of 12 days, he developed cardiopulmonary arrest after crying out. A monitored ECG showed ventricular tachycardia. Twenty minutes after onset, a 12-lead ECG showed ventricular fibrillation, which returned to normal sinus rhythm with repeated DC cardioversion. Oral antiarrhythmic therapy with carteolol hydrochloride was effective. The patient showed no further symptoms after oral medication was initiated and the tumors regressed spontaneously.

Pediatric cardiac arrhythmias resulting in hemodynamic compromise

Cardiac arrhythmias in the pediatric population generally do not result in hemodynamic compromise. There are specific scenarios, however, in which an arrhythmia poses a higher risk of deterioration in a child's overall clinical condition. To minimize this risk, clinicians must be able to recognize promptly such arrhythmias, provide rapid clinical assessment, and establish appropriate interventions to avoid cardiac arrest. This article presents a brief overview of hemodynamics in children followed by a discussion of each of the arrhythmias that have a higher-than-usual potential for resulting in hemodynamic compromise. The electrocardiographic characteristics, specific clinical interventions, and nursing implications for each of these arrhythmias also are delineated.

Ventricular arrhythmias

A spectrum of distinctive clinical presentations and electrocardiographic patterns have been recognized in neonates with ventricular arrhythmias. These may range from an incidental finding on a routine physical to cardiovascular collapse due to ventricular fibrillation. It has become increasingly important that the clinician considers ventricular tachycardia in the neonate with tachycardia when the QRS normal does not appear normal. In general, isolated premature ventricular depolarizations, couplets and non-sustained ventricular tachycardia in the absence of heart disease are associated with a favorable prognosis. Most of these arrhythmias tend to resolve during the first month of life. Conversely, sustained ventricular arrhythmias associated with ischemia, myocarditis or ventricular tumors are associated with a guarded prognosis. Treatment is based on the definition of associated cardiovascular disease, support of hemodynamic status and the judicious use of antiarrhythmic agents. Finally, there has been an increased recognition of idiopathic forms of ventricular tachycardia in the neonate which are associated with a favorable prognosis and may not require pharmacologic treatment. This review will discuss these arrhythmias in neonates, associated forms of cardiovascular disease, current treatment options and long-term prognosis.

Ventricular tachycardia in neonates

Infant VT can be a devastating arrhythmia, with high mortality for those presenting with myocarditis, long QT syndrome, or cardiovascular collapse with rapid VT due to tumors. While management of these patients can be challenging and discouraging, other infants with wide QRS rhythms tend to follow a more benign course. These latter patients have accelerated idiopathic ventricular rhythm or aberrant forms of infant supraventricular tachycardia. Distinguishing these forms of wide QRS tachycardia from the more lethal forms is paramount to institution of appropriate therapies.

Syncope in the pediatric patient

Syncope in the pediatric patient is a common and usually benign event that frequently causes concern and anxiety. This article describes three general categories of syncope in children and adolescents: cardiac, noncardiac, and neurocardiogenic. The discussion includes specific pediatric issues and dissimilarities when compared to adult patients with syncope. In addition, a focused approach to the diagnostic evaluation of syncope in childhood is described.

Verapamil responsive incessant ventricular tachycardia resulting in severe ventricular dysfunction in a young child: successful management with oral verapamil

In young children with incessant ventricular tachycardia and severe ventricular dysfunction, the management of tachycardia with conventional antiarrhythmic drugs remains a major therapeutic challenge because most of these drugs can further depress myocardial function. We report a four year old boy with verapamil responsive incessant ventricular tachycardia and severe ventricular dysfunction in whom oral verapamil treatment eliminated both the arrhythmia and the picture of dilated cardiomyopathy. On oral verapamil, the patient remains asymptomatic without recurrence of the ventricular tachycardia over a follow up period of 10 months.

Clinical spectrum, therapeutic management, and follow-up of ventricular tachycardia in infants and young children

We reviewed 40 infants and young children with VT. Median maximum VT rate was 214 beats/min (range 152 to 375 beats/min). A cause was defined in 20 (50%), the most common being cardiomyopathy or myocarditis in 8 (20%). There were six deaths (15%) related to VT, three of which occurred at diagnosis and in patients less than 1 week old. In 5 of 6 deaths related to VT, a cause was defined. At follow-up, 31 (91%) of 34 survivors did not have VT. The presence of symptoms was a predictor of death related to VT. The outlook for asymptomatic patients and those who survived more than 6 months after diagnosis and who do not have progressive myocardial disease appears good.

Flecainide and amiodarone: combined therapy for refractory tachyarrhythmias in infancy

OBJECTIVES

This study assessed the safety and efficacy of combined flecainide and amiodarone therapy in controlling refractory tachyarrhythmias in infants.

BACKGROUND

Single-drug as well as standard combination medical therapy for tachyarrhythmias in infants sometimes fails. In those cases, one may consider interventional therapy. However, this option may carry a high risk of morbidity and mortality in infants. The natural history of tachyarrhythmias in infants often favors eventual resolution and reinforces the importance of selecting an effective medical regimen.

METHODS

We performed a retrospective analysis of nine infants (median age 2 months) who received combined flecainide and amiodarone therapy for attempted control of refractory tachyarrhythmias. Trough serum drug levels of flecainide were monitored, and 24-h ambulatory electrocardiographic monitoring was used to determine efficacy of therapy.

RESULTS

Single-drug treatment with flecainide or amiodarone failed in all of the infants studied. An average of four drugs failed (range one to six) before administration of combined flecainide and amiodarone therapy. During combined therapy, the flecainide dose was 70 to 110 mg/m2 per day, and that for amiodarone was 7.5 to 13.5 mg/kg per day for a mean (+/- SD) of 9 +/- 2 days to load and 5 to 12 mg/kg per day as maintenance. Successful control of tachyarrhythmias was demonstrated in seven (78%) of nine infants (95% confidence interval 46% to 99%) (three of three with congenital junctional ectopic tachycardia, three of three with supraventricular tachycardia and one of three with ventricular tachycardia). During combined therapy, flecainide trough levels ranged from 350 to 731 ng/ml. Corrected QT intervals varied from 0.440 to 0.488 ms. No proarrhythmia occurred. None of the infants required a pacemaker, and all had normal left ventricular dimensions and fractional shortening by echocardiography. Eight of nine infants had a structurally normal heart. One infant had surgical correction of an atrioventricular septal defect.

CONCLUSIONS

Combination therapy with flecainide and amiodarone appears to be safe and effective in controlling refractory tachyarrhythmias in infants. The combination of flecainide and amiodarone may obviate the need for early interventional therapy or may allow delay until the child is older.

Multiple myocardial hamartomas causing ventricular tachycardia in young children: combined surgical modification and medical treatment

OBJECTIVE

To describe two cases of incessant ventricular tachycardia caused by multiple myocardial hamartomas.

MATERIAL AND METHODS

Two infants, 13 and 14 months old, who had had multiple episodes of symptomatic tachycardia were referred to our institution. Incessant ventricular tachycardia was diagnosed. Initially, the patients received pharmacologic therapy. The recurrent tachycardia resulted in notable hemodynamic instability. No structural abnormalities were detected on the echocardiograms. In one patient, an electrophysiologic study revealed that the site of ventricular ectopic beats was in the anterolateral wall of the left ventricle, midway between the apex and the base. In the other patient, a preoperative electrophysiologic study was not undertaken because of the inability to obtain central venous access.

RESULTS

Diffuse hamartomas were found throughout the ventricular myocardium in both patients. Surgical resection and cryoablation of the lesions in combination with medical therapy helped control the tachyarrhythmia. At 7 and 17 months postoperatively, the patients were in normal sinus rhythm and were receiving medication.

CONCLUSION

In young children who have incessant ventricular tachycardia but no lesion evident on echocardiography, angiography, or other imaging modalities, a myocardial tumor should be suspected, and pharmacologic therapy should be instituted. If the medical regimen fails, surgical intervention should be undertaken, directed at areas localized by inspection and by preoperative and intraoperative electrophysiologic studies.

Suppression of incessant ventricular tachycardia in hypertrophic cardiomyopathy associated with improvement of severe left ventricular dysfunction

A 32-year-old black man presented with a history of palpitations since childhood and two syncopal episodes. He was found to have incessant ventricular tachycardia, impaired left ventricular contraction (ejection fraction 9%), and nonobstructive hypertrophic cardiomyopathy. Procainamide abolished the arrhythmia and the ejection fraction rose to 22% in sinus rhythm. Later treatment was switched to amiodarone, which suppressed the ventricular tachycardia but necessitated pacemaker implantation. He has remained well during the subsequent 2 years. Left ventricular ejection fraction has increased to 47% measured in paced rhythm. The improvement in left ventricular function has been attributed to suppression of the incessant ventricular tachycardia.

Pathology of surgically excised primary cardiac tumors

Between 1957 and March 1991, 106 patients with 110 neoplasms that originated in the heart were treated surgically at the Mayo Clinic and had pathologic material available for review. The study group consisted of 39 male and 67 female patients, who ranged in age from 2 to 80 years. Benign atrial myxomas (64 in the left atrium and 16 in the right atrium) were the most commonly encountered neoplasm. The other benign tumors were nine fibromas, five lipomatous tumors, seven valvular fibroelastic papillomas, and one cardiac hamartoma (so-called oncocytic cardiomyopathy). In addition, eight patients had a primary cardiac malignant lesion: angiosarcoma, leiomyosarcoma, and malignant fibrous histiocytoma in two patients each and sarcoma (not otherwise specified) and osteogenic sarcoma in one patient each. The angiosarcomas originated in the right atrium, and the other malignant tumors originated in the left atrium. The histologic feature that most frequently predicted an adverse clinical outcome was the presence of mitotic figures, although highly cellular tumors and those with necrosis also tended to have a malignant course.

Early and long-term results of catheter ablation in patients with incessant ventricular tachycardia

Catheter ablation of sustained monomorphic ventricular tachycardia (VT) with high energy DC shock (360-400 J) was performed in 11 patients with incessant VT (duration greater than 24 hours), refractory to antiarrhythmic drugs, and DC cardioversion. There were ten patients with coronary disease and one patient had dilated cardiomyopathy. Direct current energy was delivered at the earliest endocardial activation in six patients (group I) or at the area of slow conduction in five patients (group II). Incessant VT was terminated by DC ablation in nine patients (82%). After the ablation procedure VT remained inducible in four patients in group I (67%) and in one patient (20%) in group II. Two patients in group II had to go to emergent surgery. During the mean follow-up of 31 +/- 26 (1-66) months nonfatal VT recurrences occurred in five patients in group I and in one patient in group II.

Surgical management of dysrhythmias in infants and small children

Surgery for cardiac dysrhythmias is infrequently reported in infants and children as compared with adults. This report reviews 55 infants and small children (age, less than or equal to 5 years) operated on during the interval July 1, 1984 to December 31, 1991 for Wolff-Parkinson-White Syndrome (41), atrioventricular node reentry (two), atrial automatic tachycardia (two), and ventricular tachycardia (nine). Ages ranged from 3 weeks to 71 (mean, 29) months. Associated congenital heart defects were present in five (10%). Indications for surgery included failure of medical therapy, life-threatening dysrhythmias, and more recently, failure of catheter ablation. There were no hospital or late deaths. One patient sustained perioperative central nervous system injury. Surgery was successful in 52 of 55 (94.5%) (Wolff-Parkinson-White, 38/41 (93%); atrioventricular node reentry, 2/2 (100%); atrial automatic tachycardia, 3/3 (100%); ventricular tachycardia, 9/9 (100%). Ventricular function returned to normal in all 12 patients in whom it was abnormal before operation. Thus, surgical ablation is highly successful in the management of various forms of refractory or life-threatening dysrhythmias in infants and small children. Catheter ablation techniques require significant fluoroscopic time, are more difficult in infants, and as yet do not have adequate long-term follow-up. Accordingly, surgery may continue to play a role in this particular group of patients.

Cardiomyopathy and myocarditis in children with ventricular ectopic rhythm

OBJECTIVE

The objective of this study was to evaluate the histologic features of the myocardium in children with abnormal ventricular ectopic rhythm but a structurally normal heart.

BACKGROUND

Abnormal ventricular ectopic rhythm in children with a structurally normal heart is an uncommon but serious condition. Previous studies in adults with these findings have shown that approximately 10% have "primary electrical disease" and that 40% to 100% of these have abnormal histologic findings.

METHODS

Endomyocardial biopsy samples were obtained prospectively in 33 subjects presenting with ventricular ectopic rhythm but a structurally normal heart by physical examination and noninvasive studies. Biopsy specimens were evaluated for histologic changes consistent with dilated cardiomyopathy or myocarditis and these results were compared with noninvasive and invasive clinical findings.

RESULTS

Of the 33 subjects, 16 (48%) had normal myocardial histologic features (Group A), 14 (42%) had changes similar to the histologic features seen with idiopathic dilated cardiomyopathy (Group B) and 3 (9%) had lymphocytic myocarditis (Group C). Presenting clinical symptoms, surface electrocardiograms (ECGs), exercise stress testing and electrophysiologic stimulation tests failed to predict the biopsy results. Twenty-four-hour ambulatory ECGs showed a statistical difference between sustained and nonsustained ventricular tachycardia in Group A versus Group B (p less than 0.007), with Group A having more sustained ventricular tachycardia. Left ventricular function measured by fractional shortening on echocardiography did not differ between groups, but left ventricular end-diastolic dimension was greater in the subjects with abnormal histologic findings (Group B) (p less than 0.03).

CONCLUSIONS

These results provide evidence that approximately 50% of children with abnormal ventricular ectopic rhythm but a structurally normal heart may have subclinical cardiomyopathy or unsuspected myocarditis.

Use of amiodarone for short-term and adjuvant therapy in young patients

Limited data are available defining the safety of amiodarone for short-term use or as part of combination antiarrhythmic therapy in pediatric patients. Results of amiodarone in 47 young patients for an average treatment duration of 12 months were examined. There were 21 male and 26 female patients (age range of 23 weeks gestation to 29 years). Patients were divided into 4 groups: group 1--electrocardiographic documented ventricular tachycardia (n = 7); group 2--syncope of unknown cause (n = 16); group 3--primary atrial tachycardia (n = 11); and group 4--supraventricular tachycardia (n = 13). Amiodarone was clinically useful in 32 (68%) patients. Amiodarone was considered effective as a sole antiarrhythmic agent in 21 (45%) patients. Treatment was ineffective but was continued in 11 (23%) patients; in 10 of these 11 patients amiodarone was adjuvant to other antiarrhythmic drugs. Amiodarone was considered ineffective and was withdrawn in 15 (32%) patients. No patient required cardiac pacemaker implant during therapy. Torsades de pointes and cardiac arrest occurred in 1 patient each after 9 and 14 days of therapy, respectively. Two patients underwent successful cardiac transplant after 2 and 14 months of amiodarone administration, respectively. Amiodarone was used as short-term treatment (less than 18 months) in 7 infants (age less than 18 months), and after cessation of treatment there was no recurrence of tachycardia for 4 to 24 months. Results of this study confirm reports of successful amiodarone use in pediatric patients with a variety of rhythm disturbances.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular arrhythmias in children with an apparently normal heart

Ventricular ectopy occurs frequently in normal children. In the presence of a normal heart, these arrhythmias, including asymptomatic, nonsustained ventricular tachycardia, carry a benign prognosis and are not associated with sudden, unexpected death. However, complex ventricular arrhythmias frequently indicate the presence of underlying cardiac disease; patients with such arrhythmias must undergo an appropriately thorough evaluation before decisions regarding prognosis and the need for therapy can be made.