Tachycardia in children

For the treatment of hemodynamically stable ventricular tachycardia in children, procainamide (loading dose of 15 mg/kg IV infused over 30 to 60 minutes) may be considered as an alternative agent to amiodarone. 

Leenhardt, A., Lucet, V., Denjoy, I., etal., 1995, Catecholaminergic polymorphic ventricular tachycardia in children. A 7-year follow-up of 21 patients. Circulation, 91(5), pp 1512-9. 

Several studies have reported the efficacy and safety of adenosine and ATP in the treatment of tachycardias in children (8-11). 

Sherwood MC, Lau KC, Sholler GF. Adenosine in the management of supraventricular tachycardia in children. J Paediatr Child Health 1998 34(l) 53-6. 

Strasburger JF, Smith RT Jr, Moak JP, Gothing C, Garson A Jr. Encainide for resistant supraventricular tachycardia in children follow-up report. Am J Cardiol 1988 62(19) L50-4. 

Cardiopulmonary arrest in adults usually results from arrhythmias. The most common arrhythmias are ventricular fibrillation (VF) and pulseless ventricular tachycardia (PVT), often in patients after myocardial infarction (MI) or pulmonary embolism (PE). In children, cardiopulmonary arrest is often the terminal event of progressive shock or respiratory failure. 

Clinical signs of dehydration in children include tachycardia, loss of skin turgor and dry tongue. 

Methylphenidate is a CNS stimulant similar to amphetamine however, in usual doses it has a more expressed action on mental activity rather than physical or motor activity. In therapeutic doses it does not raise blood pressure, respiratory rate, or increase heart rate. All of these effects as well as a number of others are associated with general excitement of the CNS. Tremor, tachycardia, hyperpyrexia, and a state of confusion can result from using large doses. It is used in treating moderate depression and apathetic conditions, and also as an adjuvant drug for treating attention deficit disorder in children.Synonyms of this dmg are meridil, ritalin, and others. 

Adverse reactions with other methylphenidate hydrochloride products -Nervousness and insomnia are the most common adverse reactions reported with other methylphenidate products. In children, loss of appetite, abdominal pain, weight loss during prolonged therapy, insomnia, and tachycardia may occur more frequently however, any of the other adverse reactions listed also may occur. 

Adverse reactions may include dry skin and mucous membranes, flushing, hyperthermia, tachycardia, urinary retention (especially in children), pruritus, gum swelling, angioneurotic edema, urticaria, anaphylaxis, dizziness, drowsiness, sedation, headache, malaise, lethargy, restlessness, euphoria, depression, numbness of extremities, confusion, anorexia, nausea, vomiting, abdominal discomfort, toxic megacolon, and pancreatitis. 

Other reported side effects include vomiting, salivation, lacrimation, shivering, skin rash, and an interaction with thyroid preparations that may lead to hypertension and tachycardia. Ketamine also may raise intracranial pressure and elevate pulmonary vascular resistance, especially in children with trauma or congenital heart disease. Increases in intraocular pressure also may occur, and vigilance is required if ketamine is used in ocular surgery. 

Because of the multiple receptor sites that TCAs bind to, there are a variety of possible side effects that can be seen in treatment. The blockade of muscarinic receptors leads to increased anticholinergic tone and subsequent anti-cholinergic side effects, especially in the gastrointestinal system. These include delirium, dry mouth, tachycardia, constipation, and urinary retention in adults. In children, anticholinergic side effects are often not seen with treatment (Geller et ah, 1992). Tricyclic antidepressant blockade of the presynaptic a 2 receptors leads to increased autonomic tone throughout the body, causing elevations in heart rate and blood pressure. 

Some of the adverse effects associated with the use of psychostimulants include anorexia, nausea, weight loss, insomnia, nightmares, dizziness, irritability, dysphoria, agitation, tachycardia, cardiac arrhythmias, increase in tics and dyskinesias (Sadock and Sadock. 2001). Use of psychostimulants in children with ADHD may cause transient retardation of body growth... 

The adverse effects of TCAs are also similar to those reported in adults (see Chapter 7). The secondary amine TCAs (e.g., desipramine, nortriptyline) are generally as well tolerated as newer antidepressants. Increased blood pressure may be more likely to occur in children than in adults but hypertension per se is rare ( 135). The most common cardiovascular effect is mild tachycardia. Despite their generally favorable adverse effect profile, secondary amine TCAs can cause serious toxicity in children and adolescents just as in adults when a taken in an overdose or when a high TCA plasma level occurs as a result of slow metabolism ( 136). For that reason, most clinicians reserve TCAs for the child or adolescent who has at least a moderate depressive disorder unresponsive to a trial of one or more newer antidepressants. In such instances, TDM should be done at least once to ensure plasma concentrations greater than 450 ng/mL do not develop ( 137). Such levels are associated with an increased risk of the following ... 

The toxicity of thyroxine is directly related to the hormone level. In children, restlessness, insomnia, and accelerated bone maturation and growth may be signs of thyroxine toxicity. In adults, increased nervousness, heat intolerance, episodes of palpitation and tachycardia, or unexplained weight loss may be the presenting symptoms. If these symptoms are present, it is important to monitor serum TSH (Table 38-2), which will determine whether the symptoms are due to excess thyroxine blood levels. Chronic overtreatment with T4, particularly in elderly patients, can increase the risk of atrial fibrillation and accelerated osteoporosis. 

When used in therapeutic doses, dimercaprol is associated with a high incidence of adverse effects, including hypertension, tachycardia, nausea, vomiting, lacrimation, salivation, fever (particularly in children), and pain at the injection site. Its use has also been associated with thrombocytopenia and increased prothrombin time—factors that may limit intramuscular injection because of the risk of hematoma formation at the injection site. Despite its protective effects in acutely intoxicated animals, dimercaprol may redistribute arsenic and mercury to the central nervous system, and it is not advocated for treatment of chronic poisoning. Water-soluble analogs of dimercaprol—unithiol and succimer—have higher therapeutic indices and have replaced dimercaprol in many settings. 

Poisoning may be characterized by inebriation, muscular incoordination, blurred vision, impaired reaction time, excitement due to loss of inhibitions, impairment of consciousness, coma, tachycardia, and slow respiration. A blood alcohol level of 80 mg/dl can produce recognizable features of drunkenness a level above 300 mg/dl is life threatening. In children, severe hypoglycemia and convulsions may also occur. 

Toxic shock syndrome is a very damaging, often fatal condition caused by toxins from Staphylococcus aureus or Streptococcus pyogenes. First reported in children in 1978, it is manifested by high fever, erythroderma (a skin rash condition), and severe diarrhea.6 Patients may exhibit confusion, hypotension, and tachycardia, and they may go into shock with failure of several organs. Survivors often suffer from skin desquamation (flaky skin). 

Since the adverse effects of clozapine may be more common in children than adults, perhaps reflecting developmental pharmacokinetic differences, clozapine and its metabolites, norclozapine and clozapine-N-oxide, have been studied in six youths aged 9-16 years, with childhood onset schizophrenia (222). Dose-normalized concentrations of clozapine did not vary with age and were similar to reported adult values. Clinical improvement in five patients correlated with serum clozapine concentrations, and clinical response and total number of common adverse effects (sialorrhea, n = 5 tachycardia, n = 4 sedation, n = 1 enuresis, n = 1) correlated with norclozapine concentrations. One child had a reduced neutrophil count (1.1 x 109/1) and another child had increased hepatic transaminases. 

In 14 children under the age of 5 years with peak serum carbamazepine concentrations of 76-134 pmol/l after acute accidental overdose there was nystagmus in 12, drowsiness in 10, ataxia in four, and mild tachycardia in two (84). None died. 

Before its withdrawal in the UK cisapride was specifically contraindicated in premature babies for up to 3 months after birth, because of the risk of QT interval prolongation (10). Between 1988 and 2000 the Medicines Control Agency received 64 reports of suspected adverse effects of cisapride in children under 13 years, of which two were cases of QT prolongation and two were sudden unexplained deaths. Another 106 cardiovascular events were reported from other countries, including 30 cases of QT prolongation, six cases of ventricular fibrillation or tachycardia, and four sudden unexplained deaths. 

Musto B, D Onofrio A, Cavallaro C, Musto A, Greco R. Electrophysiologic effects and clinical efficacy of flecainide in children with recurrent paroxysmal supraventricular tachycardia. Am J Cardiol 1988 62(4) 229-33. 

In a double-blind, randomized, controlled study of 77 children undergoing halothane anesthesia for adenoidect-omy, the effects of atropine 0.02 mg/kg, glycopyrrolate 0.04 mg/kg, and physiological saline were compared (9). There was no difference in the incidence of ventricular dysrhythmias. Atropine prevented bradycardia but was associated with sinus tachycardia in most patients. The bradycardias that occurred in the groups that received glycopyrrolate or placebo were short-lived and resolved spontaneously. 

Acute poisoning with isoniazid in children (48) and adults (13,26,35) causes recurrent seizures, profound metabolic acidosis, coma, and even death. In adults, toxicity can occur with the acute ingestion of as little as 1.5 g of isoniazid. Doses larger than 30 mg/kg often produce seizures and 80-150 mg/kg or more can be rapidly fatal. The first signs and symptoms of isoniazid toxicity usually appear 0.5-2.0 hours after ingestion, by which time peak absorption occurs (49), and include nausea, vomiting, slurred speech, dizziness, tachycardia, and urinary... 

The safety of oral propafenone in the treatment of dysrhythmias has been studied retrospectively in infants and children (40). There were significant electrophysiolo-gical adverse effects and prodysrhythmia in 15 of 772 patients (1.9%). These included sinus node dysfunction in four, complete atrioventricular block in two, aggravation of supraventricular tachycardia in two, acceleration of ventricular rate during atrial flutter in one, ventricular prodysrhythmia in five, and unexplained sjmcope in one. Cardiac arrest or sudden death occurred in five patients (0.6%) two had a supraventricular tachycardia due to Wolff-Parkinson-White syndrome the other three had structural heart disease. Adverse cardiac events were more common in the presence of structural heart disease and there was no difference between patients with supraventricular and ventricular dysrhythmias. 

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