Cardiac arrhythmias normal rhythm

Cardiac arrhythmias or dysrhythmias are disturbances of the normal regular rhythm which may be caused by an abnormality in the site of impulse generation, its rate or regularity, or its propagation or conduction (1,2). The more commonly encountered cardiac arrhythmias are... 

EKGs taken on two workers about 2.5 hours after an acute exposure to hydrogen sulfide showed cardiac arrhythmias (Krekel 1964). The workers were exposed for <5 minutes after a spill of sodium sulfide that broke down to release hydrogen sulfide. In one individual, a negative P wave indicating a substitute rhythm was noted, while in the other individual a continuous arrhythmia due to atrial flutter was found. EKGs for both men had returned to normal within 24 hours. 

In the presence of cardiac arrhythmias, when the heart is beating rapidly but inefficiently, the formation of clots in atrial appendages is common. When converting to a normal sinns rhythm, the clots may be freed and become lodged in vital organs. To avoid this, patients with arrhythmias may be treated with anticoagulants before and after conversion of the arrhythmia to a sinus rhythm. 

Pharmacologic testing procedures for the cardioactive alkaloids pro- dde three types of information (1) alterations in the normal physiologic activities of the heart (2) conversion of artificial cardiac arrhythmias to normal sinus rhythm (3) compensation for the experimentally induced congestive heart failure. 

The classic publication of Frey (17) epitomizes most of the information known today about the therapy of auricular fibrillation with quinidine. He converted to normal sinus rhythm 6 of 10 patients whose auricular fibrillation was complicated by atherosclerosis, mitral stenosis or insufficiency, and rheumatic fever or congestive failure. These patients included other arrhythmias such as auricular flutter or ventricular extra systoles. Some had been digitalized. Conversion occurred after 1.0 to 1.4 g. quinidine given over 2 to 8 days. Frey (33) also distinguished between patients with paroxysmal auricular fibrillation and the more stubborn continuous fibrillation. In this latter group of patients, many of whom had serious cardiac damage, quinidine converted 11/22 to normal rhythm. 

Certain diseases and the effect of some drugs are usually responsible for aflfeeting the rhythm and the normal heart-rate. These cardiac arrhythmias may be eaused from disorders in paeemaker function of the sinoatrial node thereby resulting into tachyeardia, bradyeardia, eardiae arrest, atrial flutter, atrial fibrillation and ventricular fibrillation. Hence, the antiarrhythmie agents are also termed as antidysrhythmic drugs or antifibrillatory drugs . 

Smaller mammals have shorter Hfe spans, since the total number of heart beats in a mammaTs lifetime is invariant. Within an individual mammal, rapid (and random) heart rhythms beyond normal often result in cardiac arrhythmias, such as ventricular tachycardia. On the other hand, it is interesting to note here that cardiac slowing, which reduces heart rate, can actually have the beneficial consequence of increasing longitivity. 

Full-face phenol-based peel should be always performed under full cardiopulmonary monitoring. The average lag time for the onset of the arrhythmias was 17.5 min from the beginning of the peel, and they are usually not delayed for more than 30 min after the peel. Cardiac arrhythmias are more common while applying the solution on the thin skin of eyelids. In this area, skin absorption is maximal therefore, application should be performed extremely cautiously. If arrhythmia occurs, the application of phenol should be stopped until normal sinus rhythm returns. To reduce the incidence of arrhythmia, minimal amounts of phenol should be used during the peel. Hydration and diuresis promote metabolism and excretion of phenol and, thus, reduce arrhythmias. Proper pre-peel... 

Here s an outline of many common cardiac arrhythmias and their features, causes, and treatments. Use a normal electrocardiogram strip, if available, to compare normal cardiac rhythm configurations with the rhythm strips shown here. Characteristics of normal sinus rhythm include the following ... 

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... 

An arrhythmia can be broadly defined as any significant deviation from normal cardiac rhythm.6 Various problems in the origination and conduction of electrical activity in the heart can lead to distinct types of arrhythmias. If untreated, disturbances in normal cardiac rhythm result in impaired cardiac pumping ability, and certain arrhythmias are associated with cerebrovascular accidents, cardiac failure, and other sequelae that can be fatal.1,2 16 Fortunately, a variety of drugs are available to help establish and maintain normal cardiac rhythm. 

Antidysrhythmics restore normal cardiac rhythm in cardiac dysrhythmias. Cardiac dysrhythmia (arrhythmia) is deviation from the cardiac rate. These deviations are ... 

C. Clinical Use and Toxicities Calcium channel blockers are effective for converting atrioventricular nodal reentry (also known as nodal tachycardia) to normal sinus rhythm. Their major use is in the prevention of these nodal arrhythmias in patients prone to recurrence. These drugs are orally active verapamil is also available for parenteral use (Table 14—2). The most important toxicity of verapamil is excessive pharmacologic effect, since cardiac contractility, AV conduction, and blood pressure can be significantly depressed. See Chapter 12 for additional discussion of toxicity. Amiodarone has moderate calcium channel-blocking activity. 

Antidysrhythmics are drugs that restore normal cardiac rhythm and are used to treat cardiac dysrhythmias. A cardiac dysrh5dhmia is a disturbed heart ihythm. It is also known as arrhythmia—absence of heart ihythm. A disturbed heart rhythm is any deviation from the normal heart rate or heart pattern including slow rates (bradycardia) and fast rates (tachycardia). The electrocardiogram (ECG) is used to identify the type of dysrhythmia. 

Life sustaining devices provide therapy that keeps a patient alive. An implantable defibrillator is an example of a life sustaining device. Certain cardiac patients experience tachycardia (a very rapid heart beat) or ventricular fibrillation. Either condition limits the ability of the heart to effectively pump blood. Death can result if this type of arrhythmia is sustained and a normal heart rhythm is not restored by a defibrillator. 

Many patients suffer from rhythm disturbances early after transplantation. Commonly they have a junctional rhythm until normal sinus activity reoccurs. Intravenous isoproterenol therapy early after transplantation can maintain the heart rate about 100-120 beats per minute, optimizing the cardiac output and preventing arrhythmias. Epicar-dial (atrio-)ventricular pacing is an alternative to pharmacological therapy. Asymptomatic, transient atrial arrhythmias are common with an incidence of about 20%-25% during hospital stay. Ventricular arrhythmias are more common than atrial arrhythmias (incidence up to 60%) and reflect the ischemic and reperfusion injury (prolonged ischemia time), hypokalemia or hypomagnesemia. 

---