Arrhythmias paroxysmal

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, 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. 

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. 

The uses of the antiarrhythmic drug are given in the Summaiy Drug Table Antiarrhythmic Drug3. In general these drugp are used to prevent and treat cardiac arrhythmias, such as premature ventricular contractions (PVCs), ventricular tachycardia (VT), premature atrial contractions (PACs), paroxysmal atrial tachycardia (PAT), atrial fibrillation, and atrial flutter. Some of the antiarrhythmic dru are used for other... 

Paroxysmal supraventricular tachycardia (PSVT) is a term that refers to a number of arrhythmias that occur above the ventricles and that require atrial or AV nodal tissue for initiation and maintenance.32 The most common of these arrhythmias is... 

O Determining a correct and accurate diagnosis is essential prior to any consideration of pharmacotherapy. When a patient complains of paroxysmal, stereotypical spells that may be seizures, it must be determined if the spells are really seizures. Numerous other disorders, including syncope, psychogenic nonepileptic events (i.e., pseudoseizures), anxiety attacks, cardiac arrhythmias, hypoglycemia, transient ischemic... 

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). 

Cardiovascular manifestations include hypertension and cardiac arrhythmias (e.g., heart block, atrial flutter, paroxysmal atrial tachycardia, ventricular fibrillation, and digitalis-induced arrhythmias). In severe hypokalemia (serum concentration <2.5 mEq/L), ECG effects include ST-segment depression or flattening, T-wave inversion, and U-wave elevation. 

Flecainide is a drug used for arrhythmias and is of particular use in ventricular arrhythmias and paroxysmal atrial fibrillation. Flecainide has a membrane-stabilising activity. Use of flecainide may precipitate serious arrhythmias, even in patients with no history of cardiovascular disease and with otherwise normal hearts. 

Digitoxin is used for chronic cardiac insufficiency, tachyarrhythmia form of atrial fibrillation, paroxysmal ciliary arrhythmia, and paroxysmal supraventricular tachycaria. Synonyms of this drag are cardigin, cordalin, crystodigin, purodigin, and others. 

Qninidine exhibits all of the pharmacological properties of qninine, including antimalar-ial, fever-redncing, and other properties. Quinidine is used in varions forms of arrhythmia for preventing tachycardia and atrial fibrillation, and particularly for preventing ciliary fibrillation, paroxysmal snpraventricnlar tachycardia, extrasystole, and ventricular tachycardia. However, it is a toxic drug and is nsed relatively rarely. 

Once the arrhythmia is controlled, it may be possible to reduce the dose, as necessary, to minimize side effects or effects on conduction. PSVT and PAF The recommended starting dose is 50 mg every 12 hours. Doses may be increased in increments of 50 mg twice daily every 4 days until efficacy is achieved. For PAF patients, a substantial increase in efficacy without a substantial increase in discontinuation for adverse experiences may be achieved by increasing the flecainide dose from 50 to 100 mg twice/day. The maximum recommended dose for patients with paroxysmal supraventricular arrhythmias is 300 mg/day. 

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. 

Unlabeled Uses Control of hemodynamicallystableventriculartachycardia, control of rapid ventricular rate due to accessory pathway conduction in preexcited atrial arrhythmias, conversion of atrial fibrillation to normal sinus rhythm, in cardiac arrest with persistent ventricular tachycardia or ventricular fibrillation, paroxysmal supraventricular tachycardia, polymorphic ventricular tachycardia or wide complex tachycardia of uncertain origin, prevention of postoperative atrial fibrillation... 

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. 

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

It is indicated in ventricular arrhythmia, ventricular premature depolarization and paroxysmal ventricular tachycardia, supra-ventricular tachycardia and atrial arrhythmia. 

It is indicated in tachyarrhythmias associated with WPW syndrome, atrial flutter and fibrillation, paroxysmal tachyarrhythmias not responding to other agents. Ventricular tachycardia and ventricular arrhythmia refractory to other treatment. 

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

Digitalis is useful in the management of atrial arrhythmias because of its cardioselective parasympathomimetic effects. In atrial flutter and fibrillation, the depressant effect of the drug on atrioventricular conduction helps to control an excessively high ventricular rate. Digitalis has also been used in the control of paroxysmal atrial and atrioventricular nodal tachycardia. At present, calcium channel blockers and adenosine... 

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. 

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. 

James TN. Normal and abnormal consequences of apoptosis in the human heart. From postnatal morphogenesis to paroxysmal arrhythmias. Circulation 1994 90 556-573. 

Flecainide slows conduction in all cardiac cells including the anomalous pathways responsible for the Wolff-Parkinson-White (WPW) syndrome. Together with encainide and moricizine, it underwent clinical trials to establish if suppression of asymptomatic premature beats with antiarrhythmic drugs would reduce the risk of death from arrhythmia after myocardial infarction. The study was terminated after preliminary analysis of 1727 patients revealed that mortality in the groups treated with flecainide or encainide was 7.7% compared with 3.0% in controls. The most likely explanation for the result was the induction of lethal ventricular arrhythmias possibly due to ischaemia by flecainide and encainide, i.e. a proarrhythmic effect. In the light of these findings the indications for flecainide are restricted to patients with no evidence of structural heart disease. The most common indication, indeed where it is the drug of choice, is atrioventricular re-entrant tachycardia, such as AV nodal tachycardia or in the tachycardias associated with the WPW syndrome or similar conditions with anomalous pathways. This should be as a prelude to definitive treatment with radiofrequency ablation. Flecainide may also be useful in patients with paroxysmal atrial fibrillation. 

Clinical uses PVC, paroxysmal atrial tachycardia, AF, VT Documented life-threatening ventricular arrhythmias. Flecainide also may be used for AF and supraventricular tachycardias in patients without structural heart disease. Propafenone is also indicated for paroxysmal AF. 

Figure 3.36 A 54-year-old man with paroxysmal arrhythmias and no structural heart disease. After a crisis of paroxysmal atrial fibrillation with an average ventricular rate response of 170 beats/min that lasted 6 hours, an evident negative T wave with a slight ST-segment depression was present and slowly disappeared over the next few days. (A) Recording...

Figure 3.39 A 47-year-old man, who refers a history of paroxysmal arrhythmias, with a normal ECG. After 2 months of treatment with amiodarone, repolarisation, which was normal (A), showed a flattened and dome-like...

Other supraventricular arrhythmias, such as supraventricular paroxysmal tachycardia or atrial tachycardia secondary to an ectopic focus, are much less frequent. 

Frequently, especially in the elderly, a paroxysmal arrhythmia crisis, especially atrial fibrillation, may cause chest pain, which may have anginal characteristics and may be of long duration, in relation with the duration of the arrhythmia. In this case the possibility to be confused with ACS is high. Often, no concurrent coronary atherosclerosis is present, and basically, the impairment of diastolic properties due to the tachycardia may explain the clinical picture. In spite of the presence of severe symptoms, the lack of enzyme-level changes, in the presence of a long-duration thoracic pain and tachyarrhythmia, leads one to suspect that this is not a classical ACS, but rather pain of anginal characteristics and usually not due to ischaemia but to haemodynamic origin. 

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