Ventricular tachycardia treatment

Enca.inide, Encainide hydrochloride, a ben2amide derivative, is effective in the treatment of ventricular arrhythmias and refractory ventricular tachycardia (1,2). 

FIGURE 6-2. Algorithm for the treatment of acute (top portion) paroxysmal supraventricular tachycardia and chronic prevention of recurrences (bottom portion). Note For empiric bridge therapy prior to radiofrequency ablation procedures, calcium channel blockers (or other atrioventricular [AV] nodal blockers) should not be used if the patient has AV reentry with an accessory pathway. (AAD, antiarrhythmic drugs AF, atrial fibrillation AP, accessory pathway AVN, atrioventricular nodal AVNRT, atrioventricular nodal reentrant tachycardia AVRT, atrioventricular reentrant tachycardia DCC, direct-current cardioversion ECG, electrocardiographic monitoring EPS, electrophysiologic studies PRN, as needed VT, ventricular tachycardia.)... 

FIGURE 7-1. Advanced cardiac life support (ACLS) treatment algorithm for adult cardiopulmonary arrest. (CPR, cardiopulmonary resuscitation PEA, pulseless electrical activity PVT, pulseless ventricular tachycardia VF, ventricular fibrillation.)... 

Cardiovascular Effects. In a recent report on the clinical treatment of phenol poisoning, Langford et al. (1998) provide a summary of a case report in which a woman accidentally consumed an ounce of 89% phenol which had been mistakenly been given to her in preparation for an in-office procedure. Her immediate reaction upon consuming the phenol was to clutch her throat and collapse, and within 30 minutes she was comatose and had gone into respiratory arrest. Treatment was initiated with an endotracheal intubation. Ventilation with a bag and mask led to the detection of a lamp oil odor. Within an hour she developed ventricular tachycardia which responded to cardioversion however, she subsequently developed (in the first 24 hours) supraventricular and ventricular dysrhythmias, metabolic acidosis, and experienced a grand mal seizure. After a 15-day hospital stay, she was completely recovered with no evidence of impaired motility or compromised gastrointestinal or cardiovascular systems. 

Treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia, that are judged to be life-threatening. Because of the proarrhythmic effects, use with lesser arrhythmias is generally not recommended. 

For the treatment of hemodynamically stable ventricular tachycardia in children, procainamide (loading dose of 15 mg/kg IV infused over 30 to 60 minutes) may be considered as an alternative agent to amiodarone. 

Treatment of documented ventricular arrhythmias (eg, sustained ventricular tachycardia) considered to be life-threatening. 

Treatment of documented life-threatening ventricular arrhythmias, such as sustained ventricular tachycardia. 

Adverse reactions occurring in at least 3% of patients include angina first-degree AV block CHF intraventricular conduction delay palpitations proarrhythmia ventricular tachycardia dizziness fatigue headache constipation dyspepsia nausea/vomiting unusual taste blurred vision dyspnea. About 20% of patients discontinued treatment due to adverse reactions. 

In the treatment of life-threatening ventricular arrhythmias (ie, ventricular tachycardia) which have failed to respond to first-line antiarrhythmic agents (eg, lidocaine). 

Moricizine is indicated for the treatment of documented ventricular arrhythmias, particularly sustained ventricular tachycardia. Moricizine was evaluated in the CAST II clinical trial for the prevention of postinfarction ventricular premature complexes. It was ineffective and found to be proarrhythmic. Patients in the moricizine arm of the trial exhibited a greater incidence of sudden cardiac death than did controls. 

Clinically, tachyarrhythmias associated with digitalis excess (including supraventricular and ventricular extrasystoles) and ventricular tachycardia have been suppressed by propranolol. Although propranolol is highly effective in the treatment of digitalis-induced arrhythmias, phenytoin and Udocaine are preferred. 

Amiodarone may elicit life-threatening side effects in addition to presenting substantial management difh-culties associated with its use. The oral formulation of amiodarone is indicated only for the treatment of life-threatening recurrent ventricular arrhythmias (e.g., recurrent ventricular hbrillation and/or recurrent hemo-dynamicaUy unstable ventricular tachycardia) that have not responded to other potentially effective antiarrhythmic drugs or when alternative interventions could not be tolerated. Despite its efficacy as an antiarrhythmic agent, there is no evidence from clinical trials that the use of amiodarone favorably affects survival. 

Unlabeled Uses Acute alcohol withdrawal, arrhythmia (especially supraventricular and ventricular tachycardia), improved survival in diabetics with heart disease, mild to moderately severe CHF (adjunct) prevention of migraine, thyrotoxicosis, tremors treatment of hypertrophic cardiomyopathy, pheochromocytoma, and syndrome of mitral valve prolapse... 

It is a anticonvulsant drug and depresses the ventricular automaticity and accelerates the AV conduction. It also reduces the duration of action potential like quinidine. It also shortens the QT interval. It mainly blocks inactivated Na+ channels. It is used for the suppression of ectopic beats and for prophylaxis of recurrent paroxysmal tachycardia and also for the treatment of rapid supraventricular or ventricular tachycardia. 

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. 

It is used in the treatment of ventricular tachycardia and ventricular fibrillation. 

Papaverine Papaverine, molecular formula C20H21NO4, is an isoquinoline alkaloid isolated from poppy seeds Papaver somniferum, family Papaveraceae). This alkaloid is used mainly in the treatment of spasms and of erectile dysfunction. It is also used as a cerebral and coronary vasodilator. Papaverine may be used as a smooth muscle relaxant in microsurgery. In pharmaceutical preparations, papaverine is used in its salt form, e.g. hydrochloride, codecarboxylate, adenylate and teprosylate. The usual side-effects of papaverine treatment include polymorphic ventricular tachycardia, constipation, increased transaminase levels, hyperbihr-unemia and vertigo. 

Class I drugs have a local anaesthetic-like action, blocking the inward current in sodium channels. This depresses the fast depolarisation (phase 0) which initiates each action potential (Figure 8.5). This membrane-stabilising effect makes them valuable for the treatment of ectopic and tachycardic arrhythmias, such as atrial and ventricular fibrillation, extrasystoles, supraventricular and ventricular tachycardia. Class I drugs also decrease contractility. A sub-classification is made according to the effects on... 

These are class IC drugs with similar pharmacological profiles and with the same indication range and adverse effects. They are mainly used for the treatment of severe, lifethreatening ventricular tachyarrhythmias, and non-sustained ventricular tachycardia or high-frequency premature ventricular beats. The main adverse effects are cardiovascular, including proarrhythmic actions and severe negative inotropic effects, especially in patients with impaired cardiac function. Both flecainide and encainide increase the risk of sudden death in patients with myocardial infarction and asymptomatic unsustained ventricular arrhythmias. 

Low doses (100-200 mg/d) of amiodarone are effective in maintaining normal sinus rhythm in patients with atrial fibrillation. The drug is effective in the prevention of recurrent ventricular tachycardia. It is not associated with an increase in mortality in patients with coronary artery disease or heart failure. In many centers, the implanted cardioverter-defibrillator (ICD) has succeeded drug therapy as the primary treatment modality for ventricular tachycardia, but amiodarone may be used for ventricular tachycardia as adjuvant therapy to decrease the frequency of uncomfortable cardioverter-defibrillator discharges. The drug increases the pacing and defibrillation threshold and these devices require retesting after a maintenance dose has been achieved. 

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. 

Drugs that markedly slow conduction, such as flecainide, or high concentrations of quinidine, can result in an increased frequency of reentry arrhythmias, notably ventricular tachycardia in patients with prior myocardial infarction in whom a potential reentry circuit may be present. Treatment here consists of recognition, withdrawal of the offending agent, and intravenous sodium. 

Vomiting is common in patients with digitalis overdose. Hyperkalemia may be caused by acute digitalis overdose or severe poisoning, whereas hypokalemia may be present in patients as a result of long-term diuretic treatment. (Digitalis does not cause hypokalemia.) A variety of cardiac rhythm disturbances may occur, including sinus bradycardia, AV block, atrial tachycardia with block, accelerated junctional rhythm, premature ventricular beats, bidirectional ventricular tachycardia, and other ventricular arrhythmias. 

Quinidine is used for the maintenance of normal sinus rhythm in patients with atrial flutter or fibrillation. It is also used occasionally to treat patients with ventricular tachycardia. Because of its cardiac and extracardiac side effects, its use has decreased considerably in recent years and is now largely restricted to patients with normal (but arrhythmic) hearts. In randomized, controlled clinical trials, quinidine-treated patients are twice as likely to remain in normal sinus rhythm compared with controls. However, drug treatment was associated with a twofold to threefold increase in mortality. 

Verapamil s cardiotoxic effects are dose-related and usually avoidable. A common error has been to administer intravenous verapamil to a patient with ventricular tachycardia misdiagnosed as supraventricular tachycardia. In this setting, hypotension and ventricular fibrillation can occur. Verapamil s negative inotropic effects may limit its clinical usefulness in diseased hearts (see Chapter 12 Vasodilators the Treatment of Angina Pectoris). Verapamil can lead to atrioventricular block when used in large doses or in patients with atrio-ventricular nodal disease. This block can be treated with atropine and -receptor stimulants. In patients with sinus node disease, verapamil can precipitate sinus arrest. 

---