Supraventricular tachycardia Atrial flutter

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. 

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. 

Ventricular and supraventricular tachycardia (especially those due to re-entry phenomena), atrial fibrillation and flutter (can convert recent-onset fibrillation or flutter to sinus rhythm) Paroxysmal supraventricular tachycardia, atrial or ventricular premature beats, atrial fibrillation, or flutter (slows ventricular rate)... 

Paroxysmal supraventricular tachycardia, atrial fibrillation and flutter. Not of benefit in treatment of ventricular arrhythmias Miscellaneous... 

Ajmaline occasionally causes cardiac dysrh5dhmias (SEDA-17, 219). Of 1995 patients who were given ajmaline 1 mg/kg intravenously during an electrophysiological study, 63 developed a supraventricular tachydysrhythmia (atrial flutter, fibrillation, or tachycardia), and seven an atrioventricular re-entrant tachycardia (2). Those most at risk were older patients, those with underlying cardiac disease, and those with a history of dysrhythmias or sinus node dysfunction. 

Clinical electrophysiologic studies indicate that verapamil is effective in combating supraventricular arrythmias including atrial premature depolarizations, paroxysmal atrial tachycardia, AV nodal re-entrant paroxysmal supraventricular tachycardia, atrial fibrillation and atrial flutter (154) Verapamil is also potentially beneficial in eliminating... 

Dlgltoxin. Digitoxin is a cardiac glycoside obtained from Digitalis purpurea. Digitoxin is indicated in the treatment of atrial flutter, atrial fibrillation, and supraventricular tachycardia. Its electrophysiologic and adverse effects are similar to those described for digoxin (87). 

Common supraventricular tachycardias requiring drug treatment are atrial fibrillation (AF) or atrial flutter, paroxysmal supraventricular tachycardia (PSVT), and automatic atrial tachycardias. Other common supraventricular arrhythmias that usually do not require drug therapy are not discussed in this chapter (e.g., premature atrial complexes, wandering atrial pacemaker, sinus arrhythmia, sinus tachycardia). 

AF or atrial flutter may be manifested by the entire range of symptoms associated with other supraventricular tachycardias, but syncope is not a common presenting symptom. An additional complication of AF is arterial embolization resulting from atrial stasis and poorly adherent mural thrombi, which accounts for the most devastating complication embolic stroke. Patients with AF and concurrent mitral stenosis or severe systolic HF are at particularly high risk for cerebral embolism. 

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. 

Impulses originating at loci outside the sinus node are seen in supraventricular or ventricular extrasystoles, tachycardia, atrial or ventricular flutter, and fibrillation. In these forms of rhythm disorders, antiarrhythmics of the local anesthet-Ltillmann, Color Atlas of Pharmacology... 

Oral Premature atrial, AV junctional and ventricular contractions paroxysmal atrial (supraventricular) tachycardia paroxysmal AV junctional rhythm atrial flutter paroxysmal and chronic atrial fibrillation established atrial fibrillation when therapy is appropriate paroxysmal ventricular tachycardia not associated with complete heart block maintenance therapy after electrical conversion of atrial fibrillation or flutter. Parenteral When oral therapy is not feasible or when rapid therapeutic effect is required. 

Atrial fibrillation For the prevention of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms and paroxysmal supraventricular tachycardias (PSVT), including atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, and other supraventricular tachycardias of unspecified mechanism associated with disabling symptoms in patients without structural heart disease. 

Verapamil Severe left ventricular dysfunction cardiogenic shock and severe CHF, unless secondary to a supraventricular tachycardia amenable to verapamil therapy and in patients with atrial flutter or atrial fibrillation and an accessory bypass tract. 

Supraventricular tachycardias Use meperidine with caution in atrial flutter and other supraventricular tachycardias vagolytic action may increase the ventricular response rate. 

Class rv drugs block the slow inward Ca current (L-type calcium channel) in cardiac tissue. The most pronounced electrophysiological effects are exerted on cardiac cells that depend on the Ca" " channel for initiating the action potential, such as those found in the sinoatrial and A-V nodes. The administration of class IV drugs slows conduction velocity and increases refractoriness in the A-V node, thereby reducing the ability of the A-V node to conduct rapid impulses to the ventricle. This action may terminate supraventricular tachycardias and can slow conduction during atrial flutter or fibrillation. 

Temporary control of rapid ventricular rate in atrial flBrillation or flutter, rapid conversion of paroxysmal supraventricular tachycardia to normal sinus rhythm IV push Initially, 0.25 mg/kg actual body weight over 2 min. May repeat in 15 min at dose of 0.35 mg/kg actual body weight. Subsequent doses individualized. IV Infusion / fter initial bolus injection, may begin infusion at 5-10 mg/hr may increase by 5 mg/hr up to a maximum of 15 mg/hr. Infusion duration should not exceed 24 hr. 

Arrhythmias, including prevention of recurrent paroxysmal supraventricular tachycardia and control of ventricular resting rate in chronic atrial fibrillation or flutter (with di-goxin) PO 240-480 mg/day in 3-4 divided doses. 

Digitalis (DIGOXIN) 0.25-0.5 mg IV for paroxysmal supraventricular tachycardia (PSVT), atrial flutter and atrial fibrillation... 

It is indicated in prevention of atrial arrhythmia, atrial fibrillation or flutter, paroxysmal supraventricular tachycardia, ventricular premature beats and ventricular tachycardia. 

Digoxin Atrial fibrillation and flutter with rapid ventricular response Adenosineldiopathic and re-entrant paroxysmal supraventricular tachycardia WPW, Wolf-Parkinson-White. 

This agent also has some class lA and class II effects. It is effective for the treatment of ventricular and supraventricular tachycardias (AV nodal and accessory pathway re-entry, atrial flutter and fibrillation). Propafenone is useful in converting recent-onset atrial fibrillation or flutter to sinus rhythm, and for terminating paroxysmal supraventricular tachycardia. Its pro-ariythmic and myocardial depressant effects limit its use, especially in patients with poor ventricular function. 

Electrocardiograms typical of a variety of arrhythmias. SVT, supraventricular tachycardia AFL, atrial flutter AFib, atrial fibrillation VT, ventricular tachycardia VT-TdP, ventricular tachycardia of the torsade de pointes type. 

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. 

Endogenous norepinephrine stimulates cardiac beta receptors. Receptor-linked cAMP-dependent protein kinases phosphorylate calcium channels to increase intracellular calcium. Elevated intracellular calcium increases conduction velocity (phase 0) and decreases the threshold potential in normal SA and AV node cells (see Figure 12.13). Beta blockers slow spontaneous conduction velocity in the SA node by approximately 10-20 percent. In addition, beta blockers can slow conduction velocity while increasing the refractory period of the AV node. These effects control the ventricular rate in atrial fibrillation or flutter and terminate paroxysmal supraventricular tachycardias. They are also safer, although somewhat less effective, than other drugs for suppression of premature ventricular complexes (PVCs). Drugs in this class approved by the FDA for treatment of various arrhythmias include propranolol, acebutolol, and esmolol. Problems with the beta blockers include drowsiness, fatigue, impotence, and depressed ventricular performance. 

Therapeutic uses Verapamil and diltiazem are more effective against atrial than ventricular dysrhythmias. They are useful in treating reentrant supraventricular tachycardia and reducing ventricular rate in atrial flutter and fibrillation. In addition, these drugs are used to treat hypertension (see p. 187) and angina (see p. 177). 

Arruodarone is used in chronic ventricular arrhythmias in atrial fibrillation it both slows the ventricular response and may restore sinus rhythm it may be used to maintain sinus rhythm after cardioversion for atrial fibrillation or flutter. Amiodarone should no longer be used for the management of reentrant supraventricular tachycardias associated with the Wolff-Parkinson-White syndrome as radiofrequency ablation is preferable. 

Like all caldum channel blodcers, verapamil modulates ionic calcium influx across cell membranes of conductile and contractile myocardial cells, as well as arterial smooth muscle. The modulation of calcium influx slows atrioventricular conduction, reduces myocardial contractility and systemic vascular resistance, and results in coronary and peripheral vaso dilation. Verapamil is currently indicated for controlling angina, hypertension, paroxysmal supraventricular tachycardia, and rapid ventricular atrial flutter or fibrillation (1-5),... 

In the whole series, about 40% of the patients received adenosine unnecessarily, having atrial fibrillation or atrial flutter, and the authors suggested that misuse of this sort resulted in unnecessary expense and increased risks of adverse effects. Most of this misuse was attributed to misdiagnosis by house officers who thought that rapid atrial fibrillation was a paroxysmal supraventricular tachycardia. Very few thought that adenosine would be likely to terminate atrial fibrillation. 

---