Verapamil arrhythmia with

Arrhythmias with the use of b-adreno-receptor antagonists and verapamil together. 

E. Toxicity The calcium channel blockers cause constipation, edema, nausea, flushing, and dizziness. More serious adverse effects include congestive heart failure, atrioventricular blockade, and sinus node depression these are more common with verapamil than with the dihydropyridines. Bepridil may induce torsade de pointes and other arrhythmias. 

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. 

All antiarrhythmic dra are used cautiously in patients with renal or hepatic disease. When renal or hepatic dysfunction is present, a dosage reduction may be necessary. All patients should be observed for renal and hepatic dysfunction. Quinidine and procainamide are used cautiously in patients with CHF. Disopyramide is used cautiously in patients with CHF, myasthenia gravis, or glaucoma, and in men with prostate enlargement. Bretylium is used cautiously in patients with digitalis toxicity because the initial release of norepinephrine with digitalis toxicity may exacerbate arrhythmias and symptoms of toxicity. Verapamil is used cautiously in patients with a history of serious ventricular arrhythmias or CHF. Electrolyte disturbances such as hypokalemia, hyperkalemia, or hypomagnesemia may alter the effects of the antiarrhythmic dru . Electrolytes are monitored frequently and imbalances corrected as soon as possible... 

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. 

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. 

Concomitant use of calcium channel blockers (atenolol) Bradycardia and heart block can occur and the left ventricular end diastolic pressure can rise when beta-blockers are administered with verapamil or diltiazem. Patients with preexisting conduction abnormalities or left ventricular dysfunction are particularly susceptible. Recent acute Ml (sotalol) Sotalol can be used safely and effectively in the long-term treatment of life-threatening ventricular arrhythmias following an Ml. However, experience in the use of sotalol to treat cardiac arrhythmias in the early phase of recovery from acute Ml is limited and at least at high initial doses is not reassuring. 

This arrhythmia usually occurs in young people and preponderantly in men. The electrocardiogram often shows right bundle branch block with left axis deviation (superior axis deviation). This type of VT is often sensitive to verapamil or other calcium channel blockers, but not to /3-blockers. Radiofrequency catheter ablation may be helpful to abolish it. 

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. 

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. 

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. 

CALCIUM CHANNEL BLOCKERS SERTINDOLE Plasma concentrations of sertindole are t by diltiazem and verapamil Diltiazem and verapamil inhibit CYP3A4-mediated metabolism of sertindole Avoid co-administration raised sertindole concentrations are associated with an t risk of prolonged Q-T interval and therefore ventricular arrhythmias, particularly torsades de pointes... 

CALCIUM CHANNEL BLOCKERS DANTROLENE Risk of arrhythmias when diltiazem is given with intravenous dantrolene. Risk of 1 BP, myocardial depression and hyperkalaemia when verapamil is given with intravenous dantrolene Uncertain at present Extreme caution must be exercised when administering parenteral dantrolene to patients on diltiazem or verapamil. Monitor BP and cardiac rhythm closely watch for hyperkalaemia... 

Interactions. Several types of drug interfere with lithium excretion by the renal tubules, causing the plasma concentration to rise. These include diuretics (thiazides more than loop type), ACE inhibitors and angiotensin-11 antagonists, and nonsteroidal anti-inflammatory analgesics. Theophylline and sodium-containing antacids reduce plasma lithium concentration. The effects can be important because lithium has such a low therapeutic ratio. Diltiazem, verapamil, carbamazepine and pheny-toin may cause neurotoxicity without affecting the plasma lithium. Concomitant use of thioridazine should be avoided as ventricular arrhythmias may result. 

Interactions. Depletion of body potassium from therapy with diuretics or with adrenal steroids may lead to cardiac arrhythmias (as may be anticipated from its action on Na, K -ATPase, above). Verapamil,... 

Four categories of calcium channel blockers can be defined based on their chemical structures and actions diphenylalkylamines, benzothiazepines, dihydropyridines, and bepridil. Both diphenylalkylamines (verapamil) and benzothiazepines (diltiazem) exhibit effects on both cardiac and vascular tissue. With specificity for the heart tissue, these two types of calcium channel blockers can slow conduction through the AV node and are useful in treating arrhythmias. The dihydropyridines (nifedipine is the prototypical agent) are more potent peripheral and coronary artery vasodilators. They do not affect cardiac conduction, but can dilate coronary arteries. They are particularly useful as antianginal agents. Bepridil is unique in that it blocks both fast sodium channels and calcium channels in the heart. All calcium channel blockers, except nimodipine and bepridil, are effective in treating HTN. 

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. 

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. ... 

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