Cardiology
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A number of conventional and newer antiarrhythmic agents are available for the treatment and prophylaxis of ventricular tachycardia and sudden death. Using a multifaceted approach of programmed electrical stimulation studies, drug level determinations, exercise tolerance testing, and 24-hour ambulatory electrocardiographic monitoring, the physician can identify those patients who require therapy and then predict the likelihood of efficacy with each antiarrhythmic agent. ⋯ Serious adverse reactions necessitate a change in antiarrhythmic therapy, as opposed to lowering drug dosage to an ineffective level. The unacceptably high incidence of sudden death due to electrical instability can be reversed only by a rigorous and dedicated long-term approach to the management of serious ventricular arrhythmias.
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Localization procedures are required in catecholamine-producing tumors after clinical and biochemical confirmation. Computed tomography, ultrasound and/or 131I-metaiodobenzylguanidine (131I-MIBG) scintigraphy was performed in patients with pheochromocytoma, neuroblastoma and metastases of carcinoid tumors. Whereas computed tomography and ultrasound reflect morphological abnormalities, adrenomedullary scintigraphy depends on hormonal activity and other factors. 131I-MIBG scintigraphy has the advantage of detecting extraadrenal, multilocular and malignant pheochromocytomas. Especially small lesions and tumor tissue in bone marrow in children with neuroblastoma can be visualized more easily.
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beta-Adrenergic blockade represents a major pharmacologic advance. These drugs bind to membrane adrenergic receptors interfering with the effects of endogenous catecholamines. ⋯ The drugs have varying pharmacodynamic properties that may modify certain side effects: beta 1-selectivity, partial agonism, alpha-adrenergic blocking activity, membrane stabilization, and varying pharmacokinetic characteristics. The drugs have been shown to be relatively safe and useful for a wide variety of cardiovascular and noncardiovascular disease states, and their wide spectrum of therapeutic activity illustrates the importance of the sympathetic nervous system in the pathophysiology of medical illness.