Verapamil supraventricular arrhythmia

Other agents are also used for the treatment of manic-depressive disorders based on preliminary clinical results (177). The antiepileptic carbamazepine [298-46-4] has been reported in some clinical studies to be therapeutically beneficial in mild-to-moderate manic depression. Carbamazepine treatment is used especially in bipolar patients intolerant to lithium or nonresponders. A majority of Hthium-resistant, rapidly cycling manic-depressive patients were reported in one study to improve on carbamazepine (178). Carbamazepine blocks noradrenaline reuptake and inhibits noradrenaline exocytosis. The main adverse events are those found commonly with antiepileptics, ie, vigilance problems, nystagmus, ataxia, and anemia, in addition to nausea, diarrhea, or constipation. Carbamazepine can be used in combination with lithium. Several clinical studies report that the calcium channel blocker verapamil [52-53-9] registered for angina pectoris and supraventricular arrhythmias, may also be effective in the treatment of acute mania. Its use as a mood stabilizer may be unrelated to its calcium-blocking properties. Verapamil also decreases the activity of several neurotransmitters. Severe manic depression is often treated with antipsychotics or benzodiazepine anxiolytics. 

Dihydropyridine channel blockers (e.g., nifedipine) have little benefit on clinical outcomes beyond symptom relief. The role of verapamil and diltiazem appears to be limited to symptom relief or control of heart rate in patients with supraventricular arrhythmias in whom /l-blockers are contraindicated or ineffective. 

Verapamil is used for preventing angina pectoris attacks, arterial hypertension, and treating and preventing supraventricular arrhythmia (paroxysmal supraventricular tachycardia, atrial fibrillation, atrial flutter, extrasystole). Synonyms of this drug are isoptin, calan, fmoptin, falicard, manidone, and many others. 

Verapamil possesses antiarrhythmic, antianginal, and hypotensive activity. It reduces the myocardial need for oxygen by reducing contractility of the myocardium and slowing the frequency of cardiac contractions. It causes dilation of coronary arteries and increased coronary blood flow. It reduces tonicity of smooth musculature, peripheral arteries, and overall peripheral vascular resistance. It provides antiarrhythmic action in supraventricular arrhythmia. 

Verapamil is used to prevent attacks of stenocardia, arterial hypertension, and to treat and prevent supraventricular arrhythmia. 

CCAs (channel blockers influx inhibitors) have been used primarily for the treatment of cardiovascular disorders (e.g., supraventricular arrhythmias, angina, and hypertension). Agents such as verapamil exert their effects by modulating the influx of Ca across the cell membrane, thus interfering with calcium-dependent functions. Based partly on the common effects of lithium and this class of drugs (e.g., effects on Ca "" activity), the CCAs have been studied as a potential treatment for mania. Janicak et al. (251) reported the results of a 3-week, double-blind comparison of verapamil versus placebo, which did not demonstrate a beneficial effect for verapamil (up to 480 mg/day) in 33 acutely manic hospitalized patients. 

Diltiazem appears to be similar in efficacy to verapamil in the management of supraventricular arrhythmias, including rate control in atrial fibrillation. An intravenous form of diltiazem is available for the latter indication and causes hypotension or bradyarrhythmias relatively... 

These agents appear to be similar in efficacy to verapamil in the management of supraventricular arrhythmias, including rate control in atrial fibrillation. An intravenous form of diltiazem is available for the latter indication and causes hypotension or bradyarrhythmias relatively infrequently. Bepridil also has action potential- and QT-prolonging actions that theoretically may make it more useful in some ventricular arrhythmias but also create the risk of torsade de pointes. Bepridil is only rarely used, primarily to control refractory angina. 

Adenosine is the treatment of choice for diagnosis and reversal of supraventricular arrhythmias. Verapamil is an alternative for the management of narrow complex tachycardias. Amiodarone is the most effective drug at reversing atrial fibrillation, and in prevention of ventricular arrhythmias, but has several adverse effects. 

Although earlier trials suggested that verapamil and diltiazem may provide improved benefit in selected patients, the large Incomplete Infarction Trial of European Research Collaborators Evaluating Prognosis post-Thrombolysis (INTERCEPT) has dampened the interest for the use of diltiazem in patients receiving fibrinolytics. In this trial, the use of extended-release diltiazem had no effect on the 6-month risk of cardiac death, MI, or recurrent ischemia. Therefore, the role of verapamil or diltiazem appears to be limited to relief of ischemia-related symptoms or control of heart rate in patients with supraventricular arrhythmias for whom /8-blockers are contraindicated or ineffective. ... 

A group of clinicians who had used single 400-mg oral doses of disopyramide successfully and with few adverse effects for reverting acute supraventricular arrhythmias, reported 5 cases of profound hypotension and collapse. Three of the patients developed severe epigastric pain. All 5 had previous myocardial disease and/or were taking myocardial depressants, either beta blockers or verapamil in small quantities [not specified]. ... 

Verapamil. Verapamil hydrochloride (see Table 1) is a synthetic papaverine [58-74-2] C2qH2 N04, derivative that was originally studied as a smooth muscle relaxant. It was later found to have properties of a new class of dmgs that inhibited transmembrane calcium movements. It is a (+),(—) racemic mixture. The (+)-isomer has local anesthetic properties and may exert effects on the fast sodium channel and slow phase 0 depolarization of the action potential. The (—)-isomer affects the slow calcium channel. Verapamil is an effective antiarrhythmic agent for supraventricular AV nodal reentrant arrhythmias (V1-2) and for controlling the ventricular response to atrial fibrillation (1,2,71—73). 

The answer is e. (Hardman, pp 858-874.) Because verapamil, a Ca channel blocker, has a selective depressing action on AV nodal tissue, it is an ideal drug for both immediate and prophylactic therapy of supraventricular tachycardia (SVT). Nifedipine, another Ca channel blocker, has little effect on SAT Lidocaine and adenosine are parenteral drugs with short ha If-lives and, thus, are not suitable for prophylactic therapy. Procainamide is more suitable for ventricular arrhythmias and has the potential for serious adverse reactions with long-term use. 

The prominent depressant action of verapamil and diltiazem at the SA and A-V nodes finds use in specific arrhythmias. They are of proven efficacy in acute control and long-term management of paroxysmal supraventricular tachycardia (see Chapter 16).Their ability to inhibit conduction at the A-V node is employed in protecting ventricles from atrial tachyarrhythmias, often in combination with digitalis or propranolol. 

Supraventricular tachycardia is the major arrhythmia indication for verapamil. Adenosine or verapamil are preferred over older treatments (propranolol, digoxin, edrophonium, vasoconstrictor agents, and cardioversion) for termination. Verapamil can also reduce the ventricular rate in atrial fibrillation and flutter. It only rarely converts atrial flutter and fibrillation to sinus rhythm. Verapamil is occasionally useful in ventricular arrhythmias. However, intravenous verapamil in a patient with sustained ventricular tachycardia can cause hemodynamic collapse. 

Make a firm diagnosis. A firm arrhythmia diagnosis should be established. For example, the misuse of verapamil in patients with ventricular tachycardia mistakenly diagnosed as supraventricular tachycardia can lead to catastrophic hypotension and cardiac arrest. As increasingly sophisticated methods to characterize underlying arrhythmia mechanisms become available and are validated, it may be possible to direct certain drugs toward specific arrhythmia mechanisms. 

Verapamil and diltiazem are prototypic calcium channel blockers. As indicated previously, these drugs influence cardiac function by blocking inward calcium movement through L channels. In so doing they block conduction velocity in SA and AV node cells. They are used therapeutically to treat reentry arrhythmias through the AV node as well as paroxysmal supraventricular tachycardias. In fact, verapamil has been reported to terminate 60-80 percent of paroxysmal supraventricular tachycardias within several minutes. However, because of their potent effect on AV conduction, these drugs are contraindicated in patients with preexisting conduction problems since they may produce complete AV block. 

As noted above, the antiarrhythmic drugs can modify impulse generation and conduction. More than a dozen such drugs that are potentially useful in treating arrhythmias are currently available. However, only a limited number of these agents are clinically beneficial in the treatment of selected arrhythmias. For example, the acute termination of ventricular tachycardia by lidocaine or supraventricular tachycardia by adenosine or verapamil are examples in which antiarrhythmic therapy results in decreased morbidity. In contrast, many of the antiarrhythmic agents are now known to have lethal proarrhythmic actions, that is, to cause arrhythmias. 

Verapamil. Verapamil. S-. T.4-dimcthoxyphcnethyl -methylamino)-2-(3.4-dimcthoxyphenyl)-2-isopropylvalcro-nitrile (Calan. Isoptin). was introduced in 1962 as a coronary vasodilator and is the prototype of the Ca antagonists u.sed in cardiova.sculur diseases. It i.s u.scd in the treatment of angina pectoris, arrhythmias from Lschcmic myocardial. syndromes, and supraventricular airhythmia.s. 

Verapamil, proprietaiy name Calan, is a calcium channel blocker that is effective in the treatment of various cardiovascular disorders, including angina (classical and variant), arrhythmias (paroxysmal supraventricular tachycardia), atrial flutter, atrial fibrillation, hypertrophic cardiomyopathy (idiopathic hypertrophic subaortic stenosis), hypertension, congestive heart failure, and Raynaud s phenomenon, along with the preservation of ischemic myocardium and the treatment of migraine headaches. 

The only calcium channel blocking drug to have been licensed for the treatment of cardiac arrhythmias is verapamil. Its main uses are in the treatment of supraventricular tachycardia (SVT) and paroxysmal SVT. Because verapamil lengthens the ERP and FRP of the AV node and prolongs AV nodal conduction time [16], it can be used to control the ventricular rate in atrial fibrillation or atrial flutter and it usually terminates re-entry arrhythmias involving the AV node [208, 209], However, intravenous verapamil should not be given to patients who have the Wolff-Parkinson-White syndrome and atrial... 

Verapamil hydrochloride is mostly advocated in the control and management ofsupraventricular arrhythmias and angina pectoris. It also finds its usefulness in the treatment of supraventricular tachycardias. 

Further reports have appeared of serious circulatory depression after administration of verapamil to patients with pre-existing impairment of cardiac function. Systolic blood pressure fell in every one of 27 patients with supraventricular tachycardia treated with intravenous verapamil in most instances the fall was of the order of 20 mm Hg and of no serious significance, but in one patient with old myocardial infarction, the pressure fell from 120 mm Hg to 60 mm Hg it subsequently recovered spontaneously (57 ). Severe circulatory failure (cardiogenic shock) was precipitated by verapamil on 9 occasions in 6 patients the drug was given intravenously on 2 occasions and orally on 7 (SS ). All the patients had underlying cardiac abnormalities, but 2 had shown no evidence of cardiac failure prior to the onset of the paroxysmal arrhythmia. Two patients... 

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