Paroxysmal atrial arrhythmias

There are several important consequences of programming a PVARP that is unnecessarily long. As indicated in the following, the PVARP has important effects on the behavior of the pacing system at high atrial rates. In addition, the occurrence of atrial pacing after an intrinsic P wave may result in the induction of paroxysmal atrial arrhythmias such as atrial fibrillation. 

The association of sinus node dysfunction with paroxysmal atrial arrhythmias has long been recognized and presents some specific issues with respect to pacing (32). Until relatively recently, patients with sinus node dysfunction and paroxysmal atrial arrhythmias were usually required to be paced in the WIR... 

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... 

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. 

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... 

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. 

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... 

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...

First degree, second degree (Mobitz type I), third degree AV junctional escape rhythms, junctional tachycardia Atrial arrhythmias with slowed AV conduction or AV block Particularly paroxysmal atrial tachycardia with AV block Sinus bradycardia... 

Flecainide is an alternative to lidocaine for the treatment of ventricular arrhythmia and can be used orally for disabling paroxysmal atrial fibrillation. 

Metaraminol (aramine) is a mixed-acting agent an agonist at vascular a adrenergic receptors and an indirectly acting agent that stimulates the release ofNE. The drug has been used in the treatment of hypotensive states or off-label to relieve attacks of paroxysmal atrial tachycardia, particularly those associated with hypotension (see Chapter 34 for preferable treatments of this arrhythmia). 

Persistent and paroxysmal atrial fibrillation (AF) are potent risk factors for first and recurrent stroke. It has been estimated that AF affects more than 2,000,000 Americans and becomes more frequent with age, being the most frequent cardiac arrhythmia in the elderly [6,38], The prevalence of AF peaks at 8.8% among people over the age of 80 years, hi the Framingham Stroke Study, 14% of strokes occurred because of AF. The absolute risk of stroke in patients with AF varies 20-fold, according to age and the presence of vascular risk factors [6,7]. Several stroke risk stratification schemes have been developed and validated. Overall, patients with prior stroke or transient ischanic attack carry the highest stroke risk [6,39]. 

Class IC agents dissociate very slowly front Na" channels (10-20 s) and strongly depress conduction in the myocardium. FIccainide is mainly u< cd in the prophylaxis of paroxysmal atrial fibrillation but il has a negative inotropic action and may cause serious ventricular arrhythmias. 

B. With chronic intoxication, visual disturbances, weakness, sinus bradycardia, atrial fibrillation with slowed ventricular response rate or junctional escape rhythm, and ventricular arrhythmias (ventricular bigeminy or trigeminy, ventricular tachycardia, bidirectional tachycardia, and ventricular fibrillation) are common. Accelerated junctional tachycardia and paroxysmal atrial tachycardia with block are frequently seen. Hypokalemia and hypomagnesemia from chronic diuretic use may be evident and appear to worsen the tachyarrhythmias. 

If a patient is over-digitalised, signs of toxicity will occur, which may include loss of appetite, nausea and vomiting, and bradycardia. These symptoms are often used as clinical indicators of toxicity, and a pulse rate of less than 60 bpm is usually considered to be an indication of over-treatment. Note that paroxysmal atrial tachycardia with AV block and junctional tachycardia can also occur as a result of digitalis toxicity. Other symptoms inelude visual disturbances, headache, drowsiness and occasionally diarrhoea. Death may result from cardiac arrhythmias. Patients treated for eardiac arrhythmias can therefore demonstrate arrhythmias when they are both under- as well as over-digitalised. 

Scarring was the second most common com-plicahon reported, with the most frequent sites being the lip, chin, and perioral areas [315]. Thirteen percent of these plastic surgeons had experienced systemic cardiac complicahons (tachycardia, arrhythmias, premature ventricular contractions (PVCs), paroxysmal atrial tachycardia (PAT), and hypertension) during phenol peeling [315]. Of these, tachycardia was the most frequent [315]. An 11-year-old boy treated with phenol for xeroderma pigmentosum developed multifocal ventricular arrhythmias with heart rates up to 220 beats/min [329]. 

RED FLAG At toxic levels, digoxin may cause numerous arrhythmias, including paroxysmal atrial tachycardia with block, AV block, atrial and junctional tachyarrhythmias, and ventricular arrhythmias. 

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... 

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). 

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. 

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. 

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. 

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 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... 

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, 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. 

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