Extrasystoles

QuinidJne. Quinidine, an alkaloid obtained from cinchona bark (Sinchona sp.), is the dextrorotatory stereoisomer of quinine [130-95-0] (see Alkaloids). The first use of quinidine for the treatment of atrial fibrillation was reported in 1918 (12). The sulfate, gluconate, and polygalacturonate salts are used in clinical practice. The dmg is given mainly by the oral (po) route, rarely by the intravenous (iv) route of adniinistration. It is the most frequentiy prescribed po antiarrhythmic agent in the United States. The clinical uses of quinidine include suppression of atrial and ventricular extrasystoles and serious ventricular arrhythmias (1 3). 

Ventricular extrasystoles are treated only if they may degenerate into life-threatening arrhythmia. In milder forms the proarrhythmic risk of the diugs overshadows their benefits. In such cases (3-adrenoceptor antagonists may be attempted. For the treatment of ventricular extrasystoles, such as series or runs of extrasystoles, amiodarone or sotalol are used. In the absence of structural heart disease, class I anti-arrhythmic diugs can be considered an alternative. However, they may not be administered during the post-infarction period. 

This is not a distinct clinical entity. The most frequent form of the condition is primarily associated with severe cardiac dysfunction often in combination with dysmorphy. It is confusing, however, because a paralytic attack is accompanied by extrasystoles and tachycardia. Serum may be high, low or normal. A familial form of the disorder is exacerbated by cold and high but is relieved by Na loading. It is, however, not associated with any specific changes in serum K. ... 

Cardiovascular Effects. In one case study, a woman who had accidentally consumed about 20 mL of trichloroethylene was reported to have suffered a myocardial infarction within 2 hours of ingestion (Morreale 1976). In two other case studies, men who ingested 350 and 500 mL of trichloroethylene had ventricular arrhythmias that persisted for up to 3 days (Dhuner et al. 1957). The arrhythmias were described as ventricular tachycardia with extrasystoles from different ventricular foci. Cardiac arrhythmia was also reported in a women who drank an unknown amount of trichloroethylene (Perbellini et al. 1991). 

Extremely heavy coffee drinkers often have tachycardia and extrasystoles. 

Ivabradine is used in the treatment of angina in patients in normal sinus rhythm. It acts on the sinus node resulting in a reduction of the heart rate. It is contraindicated in severe bradycardia (heart rate lower than 60 beats/ minute), cardiogenic shock, acute myocardial infarction, moderate-to-severe heart failure, immediately after a cerebrovascular accident, second and third-degree heart block and patients with unstable angina or a pacemaker. Side-effects include bradycardia, first-degree heart block, ventricular extrasystoles, headache, dizziness and visual disturbances, including blurred vision. 

Signs of intoxication are (1) cardiac arrhythmias, which under certain circumstances are life-threatening, e.g., sinus bradycardia, AV-block, ventricular extrasystoles, ventricular fibrillation (ECG) (2) CNS disturbances — altered color vision (xanthopsia), agitation, confusion, nightmares, hallucinations (3) gastrointestinal — anorexia, nausea, vomiting, diarrhea (4) renal — loss of electrolytes and water, which must be differentiated from mobilization of accumulated edema fluid that occurs with therapeutic dosage. 

Sinus bradycardia. An abnormally low sinoatrial impulse rate (<60/min) can be raised by parasympatholytics. The quaternary ipratropium is preferable to atropine, because it lacks CNS penetrability (p. 107). Sympathomimet-ics also exert a positive chronotropic action they have the disadvantage of increasing myocardial excitability (and automaticity) and, thus, promoting ectopic impulse generation (tendency to extrasystolic beats). In cardiac arrest epinephrine can be used to reinitiate heart beat... 

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... 

Lidocaine is the most widely used local anesthetic. Its excellent therapeutic activity is fast-acting and lasts sufficiently long to make it suitable for practically any clinical use. It stabilizes cell membranes, blocks sodium channels, facilitates the secretion of potassium ions out of the cell, and speeds up the repolarization process in the cell membrane. It is used for terminal infiltration, block, epidural, and spinal anesthesia during operational interventions in dentistry, otolaryngology, obstetrics, and gynecology. It is also used for premature ventricular extrasystole and tachycardia, especially in the acute phase of cardiac infarction. Synonyms for this drug are xylocaine, neflurane, and many others. 

Propranolol is used in treating arterial hypertonicity, angina, extrasystole, superventric-ular arrhythmia, ventricular tachycardia, migraines, hypertrophic subaortic stenosis, and pheochromocytoma. It also is used in the postanginal phase of myocardial infarctions. Universally accepted synonyms of this drug are anaprilin, inderal, and many others. 

Metoprolol is nsed in moderate hypertension, serions conditions of myocardial infarction, for preventing death of cardiovascular tissue, in angina, tachycardia, extrasystole, and for secondary prophylaxis after a heart attack. The most common synonyms are lopresor, betaloc, and others. 

Pindolol, like nadolol, is a nonselective 8-adrenoblocker. It possesses antianginal, antihypotensive, and antiarrythmic action. It is used for arterial hypertension, angina stress (preventing attacks), supraventricular tachycardia, tachsystohc form of atrial fibrillation, and superventricular extrasystole. Synonyms of this drug are carvisken, visken, 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. 

Like procainamide, lidocaine is an amide with local anesthetizing action. Lidocaine is usually administered intravenously for short-term therapy of ventricular extrasystole, tachycardia, especially in the severe phase of myocardial infarction, arrhythmia of natural cause, and for arrhythmia that can originate in the heart during surgical manipulations. Synonyms of this drug are lidopen, xylocaine, xylocard, and others. 

Mexiletine is used for ventricular extrasystole and ventricular tachycardia, and ventricular fibrillation (including during the severe period of myocardial infarction). A synonym of this drug is mexitil. 

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. 

Cardiovascular - Ang na pectoris aggravated, arrhythmia, arrhythmia atrial, atrial fibrillation, bradycardia, bundle branch block, cardiac failure, extrasystole, heart murmur, heart sound abnormal, hypertension, hypotension. Ml, palpitation, Q-wave abnormality, tachycardia, ventricular tachycardia (5% or less). 

Torsades de pointes Procainamide may aggravate this special type of ventricular extrasystole or tachycardia instead of suppressing it. 

Other-Fever, flushing hyperglycemia inappropriate antidiuretic hormone syndrome rash alopecia. Ethylenediamine in aminophylline can cause sensitivity reactions, including exfoliative dermatitis and urticaria. Cardiovascular Palpitations tachycardia extrasystoles hypotension circulatory failure life-threatening ventricular arrhythmias. 

Adverse reactions may include transient stinging and burning eye pain/ache browache headache allergic lid reaction conjunctival hyperemia conjunctival or corneal pigmentation ocular irritation (hypersensitivity) localized adrenochrome deposits in conjunctiva and cornea (prolonged use) reversible cystoid macular edema (may result from use in aphakic patients) palpitations tachycardia extrasystoles cardiac arrhythmia hypertension faintness. 

Cardiovascular Effects. A woman who swallowed 500-750 ml of a concentrated cresol mixture exhibited tachycardia with polymorphic ventricular extrasystoles shortly after exposure (Labram and Gervais 1968). This was followed within 26 hours by ventricular fibrillation and cardiac arrest. 

Diamond GA, Forrester JS, deLuz PL, Wyatt HL, Swan HJ. Post-extrasystolic potentiation of ischemic myocardium by atrial stimulation. Am Heart J 1978 95 204-209... 

The indirect sympathomimetic drugs can be used clinically for systemic or local vasoconstriction. Since the mechanism is an increase in the noradrenaline concentration there are always jSi-adrenoceptor-mediated effects like tachycardia and extrasystoles. Since the re-uptake of noradrenaline is necessary to sufficiently refill the axonal vesicles, a frequent use of indirect sympathetic drugs results in a loss of efficacy by transmitter exhaustion. This phenomenon of use-dependent loss of effect is called tachyphylaxis. 

Propranolol alone or in conjunction with digitalis can help control the ventricular rate in patients with atrial flutter or atrial fibrillation. Patients with supraventricular extrasystoles and intermittent paroxysms of atrial fibrillation may benefit from (3-receptor blockade with propranolol. 

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. 

Toxicity associated with the methylxanthines usually takes the form of nervousness, insomnia, and in severe cases, delirium. Cardiovascular stimulation is seen as tachycardia and extrasystoles. Excessive respiratory stimulation may occur, and diuresis may be prominent. 

Excessive sympathomimetic stimulation may produce palpitations, extrasystole, tachycardia, chest pain, a slight increase in BP followed by a substantial decrease, chills, diaphoresis, and blanching of skin. 

Excessive sympathomimetic stimulation may produce palpitations, extrasystole, and chest pain. 

Ventricular extrasystoles (5.1%), ventricular tachycardia (4.9%), headache (3.6%), hypotension, orthostatic hypotension (2%)... 

Overdose may induce ventricular extrasystoles and short paroxysms of ventricular tachycardia, a sensation of fullness in the head, and tingling of the extremities. Should an excessive elevation of blood pressure occur, it may be immediately relieved by an a-adrenergic blocking agent, e.g., phentolamine. 

Headache (slight) Voiding difficulty Diarrhea Stomach ache Nausea Ventricular extrasystoles Anxiety, agitation, vomiting... 

The antiarrhythmic action is due to cardiac adrenergic blockade. It decreases the slope of phase 4 depolarization and automaticity in SA node, Purkinje fibres and other ectopic foci. It also prolongs the effective refractory period of AV node and impedes AV conduction. ECG shows prolonged PR interval. It is useful in sinus tachycardia, atrial and nodal extrasystoles. It is also useful in sympathetically mediated arrhythmias in pheochromocytoma and halothane anaesthesia. 

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