Incessant ventricular tachycardia in infants: myocardial hamartomas and surgical cure

Electrophysiological and Histopathological Characteristics of Ventricular Tachycardia Associated With Primary Cardiac Tumors

BACKGROUND

Ventricular tachycardia (VT) associated with primary cardiac tumors (PCTs) originating from the ventricles is rare, but lethal, in young patients.

OBJECTIVES

This study aimed to clarify the mechanisms underlying primary cardiac tumor-related ventricular tachycardia (PCT-VT) and establish a therapeutic strategy for this form of VT.

METHODS

Among 67 patients who underwent surgery for VT at our institute between 1981 and 2020, 4 patients aged 1 to 34 years, including 3 males, showed PCT-VT (fibroma, 2; lipoma, 1; and hamartoma, 1), which was investigated using a combination of intraoperative electroanatomical mapping and histopathological studies.

RESULTS

All 4 patients developed electrical storms of sustained VTs refractory to multiple drugs and repetitive endocardial ablations. The VT mechanism was re-entry, and intraoperative electroanatomical mapping showed a centrifugal activation pattern originating from the border between the tumor and healthy myocardium, where fractionated potentials were detected during sinus rhythm. Histopathological studies of serial sections of specimens acquired from these areas revealed tumor infiltration into the surrounding myocardium with cell disorganization, exhibiting myocardial disarray. Several myocardia entrapped in the tumor edges contributed to the development and sustainment of re-entrant VT activation. In the 2 patients in whom complete resection was unfeasible, encircling cryoablation to entirely isolate the unresectable tumor was effective in suppressing VT occurrence.

CONCLUSIONS

The mechanism underlying PCT-VT involves re-entry localized at the tumor edges. Myocardial disarray associated with tumor infiltration is a substrate for this form of VT. Cryoablation along the border between the tumor and myocardium is a promising therapeutic option for unresectable PCT-VT.

Hamartoma of Mature Cardiac Myocytes: Systematic Review

BACKGROUND

While primary cardiac tumors are rare, it has been increasingly recognized due to improvement in screening measures. However, the hamartoma of mature cardiac myocytes has been underrecognized compared to other cardiac tumors, such as cardiac myxomas and papillary fibroelastomas, and is still potentially associated with critical consequences such as sudden death. This systematic review aims to summarize the evidence regarding the hamartoma of mature cardiac myocytes and characterize the presentations and symptoms for clinicians.

METHODS

Following the PRISMA statement, we searched MEDLINE and EMBASE for all peer-reviewed articles using keywords including "hamartoma of mature cardiac myocytes" from their inception to January 2nd, 2023.

RESULTS

We included 25 articles, including 34 cases, in this systematic review. Patients with hamartoma of mature cardiac myocytes commonly presented with nonspecific symptoms such as dyspnea (35.3%), although a few presented with sudden death and syncope. The left ventricle was the common site of origin (41.2%), followed by the right atrium and ventricle. Surgery was commonly pursued for diagnosis and treatment, while a few required cardiac transplants (8.8%), and 29.4% were diagnosed with autopsy or expired.

CONCLUSION

Hamartoma of mature cardiac myocytes is a potentially underrecognized primary cardiac tumor associated with treatable yet potentially critical consequences. Given the challenges of differentiating it from malignancy such as angiosarcoma, multimodal imaging needs to be utilized to pursue a diagnosis. Future studies are warranted to develop a noninvasive diagnosis mode for cardiac tumor.

Loss of Consciousness in the Young Child

In the very young child (less than eight years of age), transient loss of consciousness represents a diagnostic and management dilemma for clinicians. While most commonly benign, syncope may be due to cardiac dysfunction which can be life-threatening. It can be secondary to an underlying ion channelopathy, cardiac inflammation, cardiac ischemia, congenital heart disease, cardiomyopathy, or pulmonary hypertension. Patients with genetic disorders require careful evaluation for a cardiac cause of syncope. Among the noncardiac causes, vasovagal syncope is the most common etiology. Breath-holding spells are commonly seen in this age group. Other causes of transient loss of consciousness include seizures, neurovascular pathology, head trauma, psychogenic pseudosyncope, and factitious disorder imposed on another and other forms of child abuse. A detailed social, present, past medical, and family medical history is important when evaluating loss of consciousness in the very young. Concerning characteristics of syncope include lack of prodromal symptoms, no preceding postural changes or occurring in a supine position, after exertion or a loud noise. A family history of sudden unexplained death, ion channelopathy, cardiomyopathy, or congenital deafness merits further evaluation. Due to inherent challenges in diagnosis at this age, often there is a lower threshold for referral to a specialist.

Cardiac Tumors: Diagnosis, Prognosis, and Treatment

Purpose of Review

Cardiac masses frequently present significant diagnostic and therapeutic clinical challenges and encompass a broad set of lesions that can be either neoplastic or non-neoplastic. We sought to provide an overview of cardiac tumors using a cardiac chamber prevalence approach and providing epidemiology, imaging, histopathology, diagnostic workup, treatment, and prognoses of cardiac tumors.

Recent Findings

Cardiac tumors are rare but remain an important component of cardio-oncology practice. Over the past decade, the advances in imaging techniques have enabled a noninvasive diagnosis in many cases. Indeed, imaging modalities such as cardiac magnetic resonance, computed tomography, and positron emission tomography are important tools for diagnosing and characterizing the lesions. Although an epidemiological and multimodality imaging approach is useful, the definite diagnosis requires histologic examination in challenging scenarios, and histopathological characterization remains the diagnostic gold standard.

Summary

A comprehensive clinical and multimodality imaging evaluation of cardiac tumors is fundamental to obtain a proper differential diagnosis, but histopathology is necessary to reach the final diagnosis and subsequent clinical management.

A Case of Ventricular Tachycardia Caused by a Rare Cardiac Mesenchymal Hamartoma

The presentation of a cardiac hamartoma, an exceedingly rare and histologically benign cardiac tumor, can be variable. We describe a case of refractory ventricular tachycardia in a patient with a cardiac mass failing multiple pharmacologic and procedural interventions, ultimately treated by cardiac transplantation and diagnosed with a mesenchymal cardiac hamartoma. (Level of Difficulty: Intermediate.).

Ventricular Tachycardia in an Infant Without Congenital Anomaly: A Case Report

Ventricular tachycardia (VT) is a serious form of arrhythmia that can be life-threatening; that’s why diagnosis and treatment are very important in order to avoid serious complications. We are reporting this case of VT which is a rare entity, especially, in healthy infants. This infant, without cardiac pathology known from birth, presented with poor food intake and grunting with hepatomegaly on clinical examination, and a heartbeat at 200/ min. The electrocardiogram (ECG) showed wide QRS complex tachycardia, and the echocardiogram showed a dilated and hypokinetic cardiomyopathy. The clinical signs and chest X-ray changes were consistent with mild cardiac failure. This presentation makes the diagnosis challenging, therefore, it is important to take a good history of the case with a complete clinical exam to achieve the correct diagnosis, and to avoid potential complications. VT of an infant may be benign but should not be diagnosed as such before eliminating serious causes.

Clinical presentations, diagnosis, and management of arrhythmias associated with cardiac tumors

Cardiac tumors are a rare cause of arrhythmias in clinical practice. They can cause a broad spectrum of arrhythmias, from low-grade ectopics to incessant ventricular tachycardias, including sudden cardiac arrest. Both primary and secondary cardiac tumors can produce arrhythmias, but not all tumors cause arrhythmias. Although cardiac tumors can cause arrhythmias in fetuses and older adults alike, only specific cardiac tumors are the underlying cause of arrhythmia in different age groups. This article reviews various cardiac tumors that are associated with arrhythmias, their clinical presentations, diagnostic features, and management.

Arrhythmia-Induced Cardiomyopathies: Mechanisms, Recognition, and Management

Arrhythmia-induced cardiomyopathy (AIC) is a potentially reversible condition in which left ventricular dysfunction is induced or mediated by atrial or ventricular arrhythmias. Cellular and extracellular changes in response to the culprit arrhythmia have been identified, but specific pathophysiological mechanisms remain unclear. Early recognition of AIC and prompt treatment of the culprit arrhythmia using pharmacological or ablative techniques result in symptom resolution and recovery of ventricular function. Although cardiomyopathy in response to an arrhythmia may take months to years to develop, recurrent arrhythmia can result in rapid decline in ventricular function with development of heart failure, suggesting residual ultrastructural abnormalities. Reports of sudden death in patients with normalized left ventricular ejection fraction cast doubt on the complete reversibility of this condition. Several aspects of AIC, including specific pathophysiological mechanisms, predisposing factors, optimal therapeutic strategies to prevent ultrastructural changes, and long-term risk of sudden death remain unresolved and need further research.

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.

Ventricular tachycardia in infants with structurally normal heart: a benign disorder

We evaluated the presentation, treatment, and outcome of infants who present with ventricular tachycardia in the first year of life. Seventy-six infants were admitted to our institution with a diagnosis of ventricular tachycardia between January, 1987 and May, 2006. Forty-five infants were excluded from the study because of additional confounding diagnoses including accelerated idioventricular rhythm, Wolff-Parkinson-White syndrome, supraventricular tachycardia with aberrancy, long QT syndrome, cardiac rhabdomyoma, myocarditis, congenital lesions, or incomplete data. The remaining 31 included infants who had a median age at presentation of 1 day, with a range from 1 to 255 days, and a mean ventricular tachycardia rate of 213 beats per minute, with a range from 171 to 280, at presentation. The infants were treated chronically with propranolol (38.7%), amiodarone (12.9%), mexiletine (3.2%), propranolol and mexiletine (9.7%), or propranolol and procainamide (6.5%). The median duration of treatment was 13 months, with a range from 3 to 105 months. Ventricular tachycardia resolved spontaneously in all infants. No patient died, or received catheter ablation or device therapy. Median age at last ventricular tachycardia was 59 days, with a range from 1 to 836 days. Mean follow-up was 45 months, with a range from 5 to 164 months, with a mean ventricular tachycardia-free period of 40 months. Infants with asymptomatic ventricular tachycardia, a structurally normal heart, and no additional electrophysiological diagnosis all had spontaneous resolution of tachycardia. Furthermore, log-rank analysis of the time to ventricular tachycardia resolution showed no difference between children who received chronic outpatient anti-arrhythmic treatment and those who had no such therapy. While indications for therapy cannot be determined from this study, lack of symptoms or myocardial dysfunction suggests that therapy may not be necessary.

Heart transplantation for ventricular arrhythmia caused by a rare hamartoma

Hamartoma of mature cardiac myocytes is a form of cardiac tumor that shares some features with hypertrophic cardiomyopathy and rhabdomyomas. Here we describe a patient with a ventricular hamartoma complicated with ventricular tachycardia. Resection was not practical because of difficulty in maintaining the ventricular geometry, so heart transplantation was done.

Giant right atrial cystic hamartoma: a case report and literature review

An 11-year-old boy presenting with palpitation and chest distress was found to have gross cardiomegaly on chest radiography. Subsequent echocardiography revealed an intramural giant cystic mass in the right atrium. An operative measure was planned to prevent acute cardiac tamponade and right coronary artery obstruction. The patient successfully underwent open cystectomy to remove the mass, which was located on the front wall of the right atrium and extended to the atrioventricular appendage. Histopathological examination confirmed a cystic hamartoma. To the best of our knowledge, this is the first reported case of a giant cystic hamartoma located on the right atrium.

TRIAL REGISTRATION NUMBER

704640.

West nile virus myocarditis causing a fatal arrhythmia: a case report

West Nile Virus is one of the most frequently reported etiologies of viral encephalitis in the USA. West Nile Virus infections among hospitalized patients manifests most commonly as neuro-invasive disease. West Nile Virus has also been reported to cause myocarditis. Arrhythmia is not an uncommon occurrence in viral myocarditis. As cases of West Nile Virus increase, it is important that the index of suspicion also increase for this uncommon complication. Physicians who are caring for West Nile Virus-infected patients need to be aware of the possibility of West Nile Virus -related myocarditis. The question arises whether a patient with an established diagnosis of West Nile Virus -meningoencephalitis should be under continuous cardiac monitoring, bearing in mind the rare, but fatal, complication of cardiac arrhythmia secondary to viral myocarditis. We present a case report of a 65-year-old man who initially presented with fever, blurry vision, and decreased oral intake who subsequently suffered a fatal arrhythmia; further laboratory tests and autopsy findings revealed the patient likely had developed encephalitis and myocarditis secondary to West Nile Virus infection.

Volumineuse tumeur cardiaque révélée par un trouble du rythme ventriculaire chez un nourrisson de 18 mois

Cardiac tumors are rare in childhood and can be revealed by arrhythmias. We report the observation of an 18-month-old infant who had an episode of ventricular tachycardia (VT) which resulted in a large intramyocardic tumour diagnosis evocating a left ventricular fibroma. A treatment by amiodarone allowed a stable reduction of the VT. The presence of an intracardiac obstruction or uncontrollable arrhythmias would lead to a surgical resection.

Substrates for sudden cardiac death

Pre-event identification of a specific cardiac substrate abnormality in a patient is an important step in preventing sudden cardiac death (SCD) in the pediatric and adult population. Certain cardiac substrate abnormalities can render the patient "at risk" for SCD and strategies for prevention of SCD in children must involve the identification and subsequent modification of these cardiac substrates.

Demonstration of MyoD1 expression in oncocytic cardiomyopathy: report of two cases and review of the literature

Oncocytic cardiomyopathy is a rare arrhythmogenic disorder usually associated with female sex, difficult-to-control arrhythmias, or sudden death of infants and children. Morphologically, it is characterized by the presence of oncocytic cells, which are diffusely distributed or form the nodular structures within the myocardium, occasionally involving the valves, with a large number of mitochondria in cytoplasms. We present two cases of oncocytic cardiomyopathy. The first case had a fatal clinical outcome, and the other case was surgically treated. The nuclear expression of skeletal muscle transcription factor MyoD1 was demonstrated in the first case, supporting the theory that oncocytic cardiomyopathy is a conduction system developmental disorder. To confirm this hypothesis, it is necessary to further investigate myogenic transcription factor program in human cardiac conduction system cells.

Primary cardiac tumours in a paediatric population

OBJECTIVE

To review the presentation, diagnosis, histology and outcome of primary cardiac tumours presenting to a paediatric cardiac unit over a 20-year period.

METHODS

Hospital records and data bases were searched for the years 1980-2000.

RESULTS

There were 12 patients with four histological tumour types including a predominance of rhabdomyoma, as well as myxoma, fibroma and myocardial hamartoma. Diagnosis was made in utero, by ultrasound in five cases and in the neonatal period in a further three cases. Six cases (50%) required surgical intervention and there were three tumour-related deaths. Two infants with large left ventricular tumours diagnosed in utero developed univentricular physiology, acting like hypoplastic left heart syndrome at birth.

CONCLUSIONS

Despite an absence of malignant histology there was significant mortality and morbidity among the patients reviewed. The development of univentricular physiology in infants with large left ventricular tumours is rare and is a difficult management problem.

Evaluation and treatment of syncope in infants

Syncope in the infant and newborn occurs as a loss of consciousness due to a variety of etiologies. Because syncope at this age may be a harbinger of sudden infant death, the symptom provokes anxiety and challenges clinicians to identify those babies with an increased risk for life threatening events. Recently introduced diagnostic tests and advances in molecular biology offer promising potential, but the population at risk remains unknown. Controversy surrounds: many potential risk factors; the value of home monitoring; and appropriate preventive and therapeutic strategies. This article reviews the differential diagnosis of syncope in children less than 18 months of age, with particular attention to those diagnoses and problems specific to the evaluation and treatment in this age group. Recommendations are presented for an efficient evaluation, which must include a careful history, complete physical examination and thorough investigation of the family history and home environment. In addition, specific diagnostic tests and a practical approach to treatment are suggested.

Left ventricular hamartoma associated with ventricular tachycardia

Cardiac hamartomas are a rare type of benign tumor affecting the heart. We describe a 33-year-old patient who presented with a wide complex tachycardia. Diagnostic imaging revealed a mass in the patient's left ventricular wall, near the apex of the heart. The mass was surgically resected and appeared benign. Its pathology was that of a hamartoma of mature cardiac myocytes. Postoperative electrophysiology evaluation showed no inducible focus and the patient remains alive and asymptomatic after 2 years of follow-up.

Fetal and neonatal arrhythmias

Perinatal arrhythmias may occur either during fetal life or in the early neonatal period. These arrhythmias include both tachycardias and bradycardias. This article presents a brief overview of fetal and neonatal arrhythmias concentrating on their presentation, diagnosis, and treatment.

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.

Unusual primary tumors of the heart

Primary tumors of the heart, with the exception of atrial myxomas, occur rarely; tumors metastatic to or directly invasive of the heart are far more common. About 75% of primary tumors are benign, and 75% of these are atrial myxomas. The benign tumors include rhabdomyomas, fibromas, papillary fibroelastomas, hemangiomas, pericardial cysts, lipomas, hamartomas, teratomas, mesotheliomas, and paragangliomas or pheochromocytomas. The last 3 may also be malignant. The malignant tumors consist of various sarcomas: myxosarcoma, liposarcoma, angiosarcoma, fibrosarcoma, leiomyosarcoma, osteosarcoma, synovial sarcoma, rhabdomyosarcoma, undifferentiated sarcoma, reticulum cell sarcoma, neurofibrosarcoma, and malignant fibrous histiocytoma. Cardiac tumors produce a large variety of symptoms through any of 4 mechanisms. Their mass can obstruct intracardiac blood flow or interfere with valve function. Local invasion can lead to arrhythmias or pericardial effusions with tamponade. Bits of tumor can embolize, causing systemic deficits when the tumors are on the left side of the heart. Finally, the tumors may cause systemic or constitutional symptoms. Some tumors, of course, produce no symptoms and become evident as incidental findings. The most useful diagnostic tool is the echocardiogram, which in almost all cases precisely locates the tumor and defines its extent. The echocardiographic appearance may also allow quite accurate prediction of the tumor type and whether it is malignant or benign. Magnetic resonance imaging serves as the next most important test where the density of T1 and T2 images may allow tumor cell type identification. With few exceptions, these tumors require operative excision. Most benign tumors can be resected completely; a few, because of their large size, cannot be, and only tumor debulking may be possible. Heart transplantation should be considered for these patients. Many of the malignant tumors cannot be resected completely, either because of the extent of local spread and invasion or because of the frequent distant metastases. Transplantation may also be an option for those with extensive local disease. The long-term results for resected benign tumors are excellent; the long-term results for sarcomas are very poor, and there are few survivors. For patients with unresectable sarcomas, radiation and chemotherapy may be used, but without great expectation of successful results.

Nonsurgical transthoracic mapping and ablation in a child with incessant ventricular tachycardia

We report the case of an 11-month-old child with incessant ventricular tachycardia who underwent two unsuccessful endocardial ablations with standard catheters and in whom the ventricular tachycardia was interrupted only during transthoracic epicardial catheter ablation. This report outlines the usefulness and safety of this novel approach in pediatric patients before surgery when endocardial ablation fails.

Diagnosis and treatment of pediatric arrhythmias

The work up of arrhythmias encountered in the pediatric patient is usually initiated by primary care providers. Proper treatment of pediatric arrhythmias necessitates recording the suspected rhythm disturbance and an evolution of the underlying cardiac structure and function.

Histiocytoid cardiomyopathy: three new cases and a review of the literature

Histiocytoid cardiomyopathy (HC), a rare arrhythmogenic disorder, presents as difficult-to-control arrhythmias or sudden death in infants and children, particularly girls. Three cases are described with autopsy findings. In two cases, yellow-tan nodules were grossly visible in the myocardium; in the third case, no gross lesions were identified. Microscopic examination in all three cases revealed multiple, scattered clusters of histiocytoid myocytes which on ultrastructural examination were filled with abnormal mitochondria, scattered lipid droplets, and scanty myofibrils. These pathologic findings are similar to those previously described. The pathogenesis of this entity remains controversial. It was recently proposed that this disorder is X-linked dominant with the associated gene located in the region of Xp22.

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.

[Incessant ventricular tachycardia and myocardial hamartomas in childhood: long-term remission after surgical treatment]

Incessant ventricular tachycardia in children 2 years old or younger is usually caused by a well-localized myocardial lesion that has been termed myocardial hamartoma. Its major clinical manifestation is a rapid and potentially fatal tachyarrhythmia that does not respond to antiarrhythmic drugs. We report a patient who underwent successful surgical excision of the hamartoma and we describe the clinical features, pathologic findings and longterm follow-up.

Results of combined pulmonary resection and cardiac operation

BACKGROUND

Concomitant lesions of the heart and lung are uncommon, but when present they pose a therapeutic challenge for thoracic surgeons. A combined procedure avoids the need for a second major thoracic procedure and may improve outcomes and provide economic benefit. However, cardiopulmonary bypass may adversely affect the natural history of pulmonary malignancies.

METHODS

The clinical records of 30 patients were reviewed who underwent simultaneous lung resection and cardiac operations between January 1982 and July 1995. Follow-up was obtained on all 30 patients (mean follow-up, 22 months; range, 1 to 100 months).

RESULTS

Twenty-four patients underwent coronary artery bypass grafting in conjunction with pulmonary resection. Six patients underwent aortic (n = 4) or mitral (n = 2) valve replacement. The pulmonary resections consisted of pneumonectomy (n = 3), lobectomy (n = 14), wedge excision (n = 12), and tracheal resection (n = 1). Twenty-one patients had pathologic findings that confirmed adenocarcinoma (n = 10), squamous cell carcinoma (n = 5), small cell carcinoma (n = 2), or other malignancy (n = 4). Tumor stage of primary lung cancers was stage I, n = 12; stage II, n = 3; and stage IIIa, n = 2. Pathologic examination revealed benign disease in 9 patients. There were two operative deaths, one due to aspiration and one due to stroke. There were three late deaths, two cardiac and one of metastatic disease. Overall late survival was 85% +/- 7% and 73% +/- 16% at 1 and 5 years, respectively. Actuarial survival for patients with malignant disease was 64% at 5 years.

CONCLUSIONS

Simultaneous cardiac operation and lung resection was not associated with increased early or late morbidity or mortality. Cardiopulmonary bypass does not adversely affect survival in patients with malignant disease. Cardiac valve replacement can be performed safely in conjunction with pulmonary resection.

Pediatric use of intravenous amiodarone: efficacy and safety in critically ill patients from a multicenter protocol

OBJECTIVE

The purpose of this study was to analyze the efficacy and safety of intravenous amiodarone in young patients with critical, drug-resistant arrhythmias.

BACKGROUND

Intravenous amiodarone has been investigated in adults since the early 1980s. Experience with the drug in young patients is limited. A larger pediatric study group was necessary to provide responsible guidelines for the drug's use before its market release.

METHODS

Eight centers obtained institutional approval of a standardized protocol. Other centers were approved on a compassionate use basis after contacting the primary investigator (J.C.P).

RESULTS

Forty patients were enrolled. Standard management in all failed. Many patients had early postoperative tachyarrhythmias (25 of 40), with early successful treatment in 21 (84%) of 25. Twelve patients had ventricular tachyarrhythmias: seven had successful therapy, and six died, none related to the drug. Eleven patients had atrial tachyarrhythmias: 10 of 11 had immediate success, but 3 later died. Fourteen patients had junctional ectopic tachycardia, which was treated with success (sinus rhythm or slowing, allowing pacing) in 13 of 14, with no deaths. Three other patients had supraventricular tachycardias, with success in two and no deaths. The average loading dose was 6.3 mg/kg body weight, and 50% of patients required a continuous infusion. Four patients had mild hypotension during the amiodarone bolus. One postoperative patient experienced bradycardia requiring temporary pacing. There were no proarrhythmic effects. Deaths (9 [23%] of 40) were not attributed to amiodarone.

CONCLUSIONS

Intravenous amiodarone is safe and effective in most young patients with critical tachyarrhythmia. Intravenous amiodarone can be lifesaving, particularly for postoperative junctional ectopic tachycardia, when standard therapy is ineffective.

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.

Mechanisms and therapy of complex arrhythmias in pediatric patients

In recent years, the distinction between the diagnostic and therapeutic techniques used in the assessment and management of pediatric and adult patients with arrhythmias has gradually blurred. Nonetheless, arrhythmias in the pediatric patient are still often different from the adult patient in one of two important ways. First, a variety of arrhythmia mechanisms remain relatively unique to the pediatric population, some because of developmental issues and others because of early presentation of an incessant tachycardia. Second, the presentation and management of certain arrhythmias is sometimes markedly affected by patient age or the presence of structural congenital heart disease. A sampling from each of the above categories is reviewed and discussed.

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.