Supraventricular tachyarrhythmia

Propafenone. Propafenone hydrochloride, an arylketone, is stmcturaHy similar to the P-adrenoceptor blocking agents. It has been in use in the former West Germany since 1977 and was introduced in the United States in 1990. Its effects may result from a combination of weak calcium channel blocking, weak nonselective -adrenoceptor blocking, and sodium channel blocking activity. Propafenone is effective in treating supraventricular tachyarrhythmias, ventricular ectopic beats, and ventricular arrhythmias. It is the most frequendy prescribed medication for ventricular arrhythmias in Europe (32). 

Elestolol sulfate is a nonselective, ultrashort acting P-adrenoceptor blocker. It has no ISA and produces weak inhibition of the fast sodium channel. The dmg is under clinical investigation for supraventricular tachyarrhythmias, unstable angina, and acute MI. In humans, flestolol has hemodynamics and electrophysiologic effects similar to those of other P-adrenoceptor blockers. The pharmacokinetics of flestolol are similar to those of esmolol. It is 50 times more potent than esmolol and the elimination half-life is 7.2 min. Recovery from P-adrenoceptor blockade is 30—45 min after stopping iv infusions. The dmg is hydrolyzed by tissue esterases and no active metabohtes of flestolol have been identified (41). 

Dmgs that mimic or inhibit the actions of neurotransmitters released from parasympathetic or sympathetic nerves innervating the heart may also be used to treat supraventricular bradyarrhythmias, heart block, and supraventricular tachyarrhythmias. Those used in the treatment of arrhythmias may be found in Table 1. 

Phenylephrine. Phenylephrine hydrochloride is an a -adrenoceptor agonist. Phenylephrine produces powerful vasoconstrictor and hypertensive responses. This results in baroreceptor activation of a reflex bradycardia and thus is useful in the treatment of supraventricular tachyarrhythmias. Unlike epinephrine [51-43-4] the actions of which are relatively transient, phenylephrine responses are more sustained (20 min after iv dosing and 50 min after subcutaneous dosing) (86). 

Supraventricular bradycardia is treated by implantation of a pacemaker device or has been treated pharmacologically with atropine. Supraventricular paroxysmal tachycardia is treated with aj marine or praj marine. Supraventricular tachyarrhythmias or AV reentrant arrhythmia typically can be terminated using adenosine. 

Class IV antiarrhythmic drugs are Ca2+ channel blockers, which predominantly slow sinus rate and atrioventricular conduction and thus are used in the treatment of supraventricular tachyarrhythmias. These drugs exert a pronounced negative inotropic effect. 

In patients with HF and supraventricular tachyarrhythmias such as atrial fibrillation, digoxin should be considered early in therapy to help control ventricular response rate. 

Dihydropyridines cause a baroreceptor-mediated reflex increase in heart rate because of their potent peripheral vasodilating effects. Dihydropyridines do not decrease AV node conduction and are not effective for treating supraventricular tachyarrhythmias. 

Indications. Verapamil is used as an antiarrhythmic drug in supraventricular tachyarrhythmias. In atrial flutter or fibrillation, it is effective in reducing ventricular rate by virtue of inhibiting AV-conduction. Verapamil is also employed in the prophylaxis of angina pectoris attacks (p. 308) and the treatment of hypertension (p. 312). Adverse effects Because of verapamil s effects on the sinus node, a drop in blood pressure fails to evoke a reflex tachycardia Heart rate hardly changes bradycardia may even develop. AV-block and myocardial insufficiency can occur. Patients frequently complain of constipation. 

Parenteral (supraventricular tachyarrhythmias) - For IV use only. Give as slow IV injection over at least 2 minutes under continuous EGG and blood pressure monitoring. An IV infusion has been used (5 mg/hour) precede the infusion... 

Class la Supraventricular tachyarrhythmias Certan ventricular tachyarrhythmias... 

Inappropriate sinus bradycardia, sinoatrial block, and bradycardia-tachycardia syndrome (bradycardia followed by supraventricular tachyarrhythmias such as atrial fibrillation) are included in this syndrome. Treatment of sick sinus syndrome is generally based upon the patients symptoms. In general, bradycardia... 

Esmolol is used in the treatment of supraventricular tachyarrhythmias for rapid control of ventricular rate and reduction of myocardial oxygen consumption. Discontinuation of administration is followed by a rapid reversal of its pharmacological effects because of es-molol s rapid hydrolysis by plasma esterases. 

Dofetilide is approved for the treatment of atrial fibrillation and atrial flutter. Because of the lack of significant hemodynamic effects, dofetilide may be useful in patients with CHF who are in need of therapy for supraventricular tachyarrhythmias. Dofetilide is not indicated for use in the setting of ventricular arrhythmias. 

Adenosine is approved for the acute management and termination of supraventricular tachyarrhythmias, in-... 

The short-acting cholinesterase inhibitor edrophonium was used to treat supraventricular tachyarrhythmias, particularly paroxysmal supraventricular tachycardia. In this application, edrophonium has been replaced by newer drugs (adenosine and the calcium channel blockers verapamil and diltiazem). 

In addition to angina, calcium channel blockers have well-documented efficacy in hypertension (see Chapter 11) and supraventricular tachyarrhythmias (see Chapter 14). They also show moderate efficacy in a variety of other conditions, including hypertrophic cardiomyopathy, migraine, and Raynaud s phenomenon. Nifedipine has some efficacy in preterm labor but is more toxic and not as effective as atosiban, an investigational oxytocin antagonist (see Chapter 17). 

Hypertensive patients with concomitant diseases The (3-blockers are useful in treating conditions that may coexist with hypertension, such as supraventricular tachyarrhythmia, previous myocardial infarction, angina pectoris, glaucoma (applied topically), and migraine headache. 

Diphenylalkylamines Verapamil [ver AP a mill] is the only member of this class that is currently approved in the United States. Verapamil is the least selective of any calcium channel blocker, and has significant effects on both cardiac and vascular smooth-muscle cells. It is used to treat angina, supraventricular tachyarrhythmias, and migraine headache. 

Docetaxel should be administered the day after trastuzumab for the first cycle because of the potential for infusion-related reactions to trastuzumab, particularly during or after the first administration. Serious adverse reactions to trastuzumab infusion that have been reported infrequently include dyspnoea (shortness of breath), hypotension, wheezing, hypertension, bronchospasm, supraventricular tachyarrhythmia, reduced oxygen saturation, anaphylaxis, respiratory distress and urticaria (itching). The majority of these events occur during or within 2.5 hours of the start of the first infusion. Should an infusion reaction occur, the infusion should be discontinued and the patient monitored until resolution of any observed symptoms - the infusion may be resumed when symptoms abate. If the first cycle is well tolerated then dosing of the drugs in future cycles may occur on the same day. 

Kopehnan HA, Horowitz LN. Efficacy and toxicity of amiodarone for the treatment of supraventricular tachyarrhythmias. Prog Cardiovasc Dis 1989 31(5) 355-66. 

Hagemeijer F. Verapamil in the management of supraventricular tachyarrhythmias occurring after a recent myocardial infarction. Circulation 1978 57(4) 751-5. 

Kobayashi Y, Atarashi H, Ino T, Kuruma A, Nomura A, Saitoh H, Hayakawa H. Clinical and electrophysiologic effects of dofetilide in patients with supraventricular tachyarrhythmias. J Cardiovasc Pharmacol 1997 30(3) 367-73. 

Gray RJ, Bateman TM, Czer LS, Conklin CM, Matloff JM. Esmolol a new ultrashort-acting beta-adrenergic blocking agent for rapid control of heart rate in postoperative supraventricular tachyarrhythmias. J Am Coll Cardiol 1985 5(6) 1451-6. 

Morganroth J, Horowitz LN, Anderson J, Turlapaty P. Comparative efficacy and tolerance of esmolol to propranolol for control of supraventricular tachyarrhythmia. Am J Cardiol 1985 56(ll) F33-9. 

Cobbe SM. Drug therapy of supraventricular tachyarrhythmias—based on efficacy or futility Eur Heart J 1994 15(Suppl A) 22-6. 

Digoxin, the most commonly used cardiac glycoside, is indicated for the treatment of CHF and for the treatment of supraventricular tachyarrhythmias. It possesses positive inotropic and electro-physiological effects resulting from the inhibition of Na, K -ATPase, which increases intracellular sodium ion concentrations. This increase in intracellular sodium ions slows down calcium extrusion from the cell, resulting in an increase in intracyto-plasmic calcium and, thereby, an increase in the contractile force. 

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